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2,339,000 |
HDACi phenylbutyrate increases bystander killing of HSV-tk transfected glioma cells.
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Malignant glioma patients have a dismal prognosis with an urgent need of new treatment modalities. Previously developed gene therapies for brain tumors showed promising results in experimental animal models, but failed in clinical trials due to low transfection rates and insufficient expression of the transgene in tumor cells, as well as low bystander killing effects. We have previously shown that the histone deacetylase inhibitor 4-phenylbutyrate (4-PB) enhances gap junction communication between glioma cells in culture. In this study, we demonstrate an activation of recombinant HSV-tk gene expression, and a dramatic enhancement of gap junction-mediated bystander killing effect by administration of the HSV-tk prodrug ganciclovir together with 4-PB. These findings that 4-PB potentiates "suicide gene" expression as well as enhances gap junctional communication and bystander killing of tumor cells justify further testing of this paradigm as an adjunct to suicide gene therapy of malignant gliomas.
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2,339,001 |
Genetic screening methods for the detection of mutations responsible for multiple endocrine neoplasia type 1.
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Identification of mutations, which cause genetic diseases can be difficult when the disease is caused by the mutation of a large gene, which contains multiple exons. Detection of these mutations by DNA sequencing can be made more efficient by using mutation detection methods for pre-screening to identify the affected exon and to screen for the presence of already identified mutations in family members. These screening methods include denaturing gradient gel electrophoresis (DGGE), temperature gradient gel electrophoresis (TGGE), single-strand conformation polymorphism, conformation-sensitive gel electrophoresis (CSGE), heteroduplex analysis and denaturing high-performance liquid chromatography (DHPLC). We discuss the advantages and shortcomings of these methods by reviewing the results of studies screening for mutations causing multiple endocrine neoplasia type 1 (MEN 1) syndrome, an autosomal dominant disorder characterized by endocrine tumours of the anterior pituitary gland, parathyroid glands, and pancreas. MEN 1 is caused by mutations of the MEN1 gene, a tumour suppressor gene, which contains one untranslated exon and nine exons. Previous studies have identified more than 400 germline and somatic mutations spreading across all the encoding sequence, and found no mutational "hot spot" or genotype-phenotype correlation. The wide diversity of mutations in the entire coding region of the MEN1 gene makes mutation screening time-consuming and expensive. We conclude that combination of mutation detection methods with DNA sequencing enhances the efficiency of identifying pathogenic mutations. However, it should be considered that experimental determination of the optimal electrophoresis conditions, such as using perpendicular electrophoresis to optimise DGGE or TGGE, is more useful than computerized algorithms to calculate these parameters.
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2,339,002 |
Genetic heterogeneity in primary hyperoxaluria type 1: impact on diagnosis.
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Primary hyperoxaluria type 1 (PH1) is an autosomal recessive disease characterized by progressive kidney failure due to renal deposition of calcium oxalate. The disease is caused by a deficiency of alanine:glyoxylate aminotransferase (AGT) which catalyzes the conversion of glyoxylate to glycine. When AGT is absent, glyoxylate is converted to oxalate which forms insoluble calcium salts that accumulate in the kidney and other organs. In the most common phenotype there is a unique phenomenon wherein AGT is mis-targeted to the mitochondria instead of the peroxisomes. The diagnosis of PH1 is complicated by heterogeneity of clinical presentation, course of the disease, biochemical markers, AGT enzymatic activity and genotype. More than 50 mutations and polymorphisms have been reported in the AGT gene; three common mutations accounting for almost 50% of PH1 alleles. The mutations are of all types, with missense making up the largest fraction. There are some mutations with apparent ethnic associations and at least one that appears to be pan-ethnic. Although correlations can in some cases be made between biochemical phenotype and genotype, correlation with clinical phenotype is complicated by the involvement of other genetic and non-genetic factors that affect disease severity. A number of polymorphisms have been described in the AGT gene some of which cause missense changes and, in some cases, alter enzyme activity. As DNA testing becomes more commonly used for diagnosis it is important to correlate observed sequence changes with previously documented changes as an aid to assessing their potential significance.
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2,339,003 |
Screening for monogenetic del(GJB6-D13S1830) and digenic del(GJB6-D13S1830)/GJB2 patterns of inheritance in deaf individuals from Eastern Austria.
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Genetically caused congenital deafness is a common trait affecting 1 in 2000 newborn children and is predominantly inherited in an autosomal recessive fashion. Genes such as the gap junction protein beta 2 (GJB2) encoding for Connexin (Cx26) and GJB6 (Cx30) are known to cause sensorineural deafness. Autosomal recessive deafness has been linked both to the monogenetic occurrence of mutated GJB2 or the GJB6 deletion del(GJB6-D13S1830) and digenic GJB2/del(GJB6-D13S1830) inheritance. Monogenetic GJB2 alterations are responsible for 25.5% of deafness in the eastern Austrian population. An additional 9.8% are heterozygous carriers of a single GJB2 mutation which is not responsible for deafness alone. Del(GJB6-D13S1830) and GJB2/del(GJB6-D13S1830) mutations have been shown to be the second most frequent cause of deafness in different populations. To address the question of the relevance of mutations in GJB6 either as a monogenetic or a digenic GJB2/del(GJB6-D13S1830) cause of deafness in this population, 76 unrelated individuals (33 families and 43 sporadic cases) were screened using PCR strategies. Similar to studies in other hard of hearing populations with similar or lower carrier frequencies of single GJB2 mutations, the presence of del(GJB6-D13S1830) was not detected in any individual within the patient group. Data therefore exclude a digenetic association of del(GJB6-D13S1830) with heterozygous GJB2 mutations as a cause of deafness in a representative sample of the population from Eastern Austria.
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2,339,004 |
Prevalence of the GJB2 mutations and the del(GJB6-D13S1830) mutation in Brazilian patients with deafness.
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Mutations in the GJB2 gene are the most common cause of sensorineural non-syndromic deafness in different populations. One specific mutation, 35delG, has accounted for the majority of the mutations detected in the GJB2 gene in many countries. The aim of this study was to determine the prevalence of GJB2 mutations and the del(GJB6-D13S1830) mutation in non-syndromic deaf Brazilians. The 33 unrelated probands were examined by clinical evaluation to exclude syndromic forms of deafness. Mutation analysis in the GJB2 gene and the testing for the del(GJB6-D13S1830) were performed in both the patients and their family members. The 35delG mutation was found in nine of the probands or in 14 of the mutated alleles. The V37I mutation and the del(GJB6-D13S1830) mutation were also found in two patients, both are compound heterozygote with 35delG mutation. These findings strengthen the importance of genetic diagnosis, providing early treatment, and genetic counseling of deaf patients.
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2,339,005 |
The tau H2 haplotype is almost exclusively Caucasian in origin.
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We have assessed the distribution of the tau H1/H2 haplotype in the publicly available reference series of samples with representatives of most racial groups. This analysis shows that the H2 haplotype is probably exclusively Caucasian in origin and its marginal occurrence in other racial groups is likely to reflect admixture. We discuss this observation in terms of the origin of the H2 haplotype and the epidemiology of the tauopathies.
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2,339,006 |
Assessment of CFTR function in rectal biopsies for the diagnosis of cystic fibrosis.
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The Ussing chamber technique has contributed significantly to our understanding of the role of ion transport in the pathogenesis of human diseases like cystic fibrosis (CF). Here, we summarize protocols developed to study the Cl- channel function of the cystic fibrosis transmembrane conductance regulator (CFTR) protein in rectal biopsies from normal individuals and CF patients. These protocols can be applied to study the function and pharmacological modulation of wild-type and mutant CFTR in the context of the native epithelium. Together with sweat testing and genetic analyses, these functional measurements may aid in establishing a diagnosis of CF.
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2,339,007 |
Microarray analysis in cystic fibrosis.
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DNA microarrays provide a versatile platform for applications including gene expression analysis and genotyping. In the case of cystic fibrosis (CF), DNA microarrays enable the measurement of gene expression levels of thousands of genes in parallel, and potentially therefore, to identify non-CFTR genes down- or up-regulated in CF, which could lead to insights into disease pathophysiology, as well as novel molecular markers and therapeutic strategies. Moreover, using optimised microarray protocols based on either primer extension analysis (i.e. minisequencing) or electronic hybridisation stringency control, the potential now exists to detect all relevant CFTR mutations on a single DNA microarray as a novel platform for CF screening.
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2,339,008 |
Diagnosis of cystic fibrosis in adults with diffuse bronchiectasis.
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We assessed the contribution of the sweat test, genotyping and nasal potential difference (NPD) in the diagnosis of cystic fibrosis (CF) in adults with diffuse bronchiectasis (DB). Among 601 adults referred for DB from 1992 to 2001, 46 were diagnosed with CF. The sweat test was positive in 37 patients and normal or intermediate in nine patients. Two CF mutations were identified in 18 patients (39%) by screening for 31 mutations and in 36 patients (78%) after complete genetic analysis. NPD was suggestive of CF in 71% of the patients. The combination of the sweat test and genetic analysis led to the diagnosis of CF in 45 patients. In the nine patients with normal or intermediate sweat test, the diagnosis was confirmed by screening for 31 mutations in five, by complete genetic screening in three, and by NPD in the remaining patient. Searching for CF should start with sweat test. If the sweat test is normal or intermediate, screening for 31 mutations may help to diagnose CF. A complete genetic analysis is indicated when only one mutation is detected and/or when other clinical features, such as obstructive azoospermia or pancreatic insufficiency, are suggestive of CF. NPD measurement is indicated in controversial cases.
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2,339,009 |
A reverse genetic screen in Drosophila using a deletion-inducing mutagen.
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We report the use of the cross-linking drug hexamethylphosphoramide (HMPA), which introduces small deletions, as a mutagen suitable for reverse genetics in the model organism Drosophila melanogaster. A compatible mutation-detection method based on resolution of PCR fragment-length polymorphisms on standard DNA sequencers is implemented. As the spectrum of HMPA-induced mutations is similar in a variety of organisms, it should be possible to transfer this mutagenesis and detection procedure to other model systems.
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2,339,010 |
Mutation in the ED1 gene, Ala349Thr, in a Korean patient with X-linked hypohidrotic ectodermal dysplasia developing de novo.
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Hypohidrotic ectodermal dysplasia (HED) is a very rare disease characterized by the virtual absence of eccrine glands, dry skin, scanty hair, and dental abnormalities. It is transmitted by an X-linked recessive gene or rarely an autosomal recessive gene. Therefore it is only males who fully express the condition. It is caused by mutations within the ED1 gene, which encodes a protein, ectodysplasin-A (EDA). Typically there is frontal bossing, saddle nose, pointed chin, a prominent supraorbital ridge with periorbital hyperpigmentation, and absence of teeth. Those affected show great intolerance to heat. In the current absence of effective treatment for many hereditary skin diseases, comprehensive, accurate prenatal or postnatal genetic counseling can provide information to parents at risk of having affected children. We report HED in a 6-year-old boy with an Ala349Thr (GCA --> ACA) missense mutation developed de novo. Both parents and a 16-week gestational age fetus were healthy. We thought direct sequencing analysis for the ED1 gene using peripheral blood or amniotic fluid was preferable for an accurate diagnosis of this disease, although there was some risk of not detecting the mutation. After the results of this study were communicated to the parents, the mother was freed of her guilty feelings of the past 6 years and has now delivered a healthy male infant.
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2,339,011 |
Investigating genetic discrimination in Australia: opportunities and challenges in the early stages.
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Genetic discrimination, defined as the differential treatment of individuals or their relatives on the basis of actual or presumed genetic differences, is an emerging issue of interest in academic, clinical, social and legal contexts. While its potential significance has been discussed widely, verified empirical data are scarce. Genetic discrimination is a complex phenomenon to describe and investigate, as evidenced by the recent Australian Law Reform Commission inquiry in Australia. The authors research project, which commenced in 2002, aims to document the multiple perspectives and experiences regarding genetic discrimination in Australia and inform future policy development and law reform. Data are being collected from consumers, employers, insurers and the legal system. Attempted verification of alleged accounts of genetic discrimination will be a novel feature of the research. This paper overviews the early stages of the research, including conceptual challenges and their methodological implications.
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2,339,012 |
Genes and geneticization? The social construction of autosomal dominant polycystic kidney disease.
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Critics of the new genetics argue that contemporary understandings of health and illness are becoming increasingly 'geneticized.' Salient implications of this critique are explored here within the context of Autosomal Dominant Polycystic Kidney Disease (PKD), a life-threatening genetic disease that causes fluid-filled cysts in the kidneys and progressive loss of renal function. Although PKD is very common, public awareness of the disease remains low and there is little clinical emphasis on hereditary aspects. Drawing upon qualitative interviews with 16 healthcare providers, 13 patients and 15 family members, this paper examines the social construction and clinical management of PKD. In particular, interviewees' perceptions of the role of genetics in PKD and views on presymptomatic testing are considered. Finding little impetus toward early diagnosis and/or presymptomatic identification of mutation carriers, we conclude that careful empirical study of PKD (or other neglected hereditary conditions) contributes new insights into factors mitigating geneticization.
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2,339,013 |
Fine mapping and identification of a candidate gene SSH1 in disseminated superficial actinic porokeratosis.
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Disseminated superficial actinic porokeratosis (DSAP) is an uncommon autosomal dominant chronic keratinization disorder, characterized by multiple superficial keratotic lesions surrounded by a slightly raised keratotic border. Thus far, although two loci for DSAP have been identified, the genetic basis and pathogenesis of this disorder have not been elucidated yet. In this study, we performed a genome-wide linkage analysis in three Chinese affected families and localized the gene in an 8.0 cM interval defined by D12S330 and D12S354 on chromosome 12. Upon screening 30 candidate genes, we identified a missense mutation, p.Ser63Asn in SSH1 in one family, a frameshift mutation, p.Ser19CysfsX24 in an alternative variant (isoform f) of SSH1 in another family, and a frameshift mutation, p.Pro27ProfsX54 in the same alternative variant in one non-familial case with DSAP. SSH1 encodes a phosphatase that plays a pivotal role in actin dynamics. Our data suggested that cytoskeleton disorganization in epidermal cells is likely associated with the pathogenesis of DSAP.
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2,339,014 |
Mutation analysis of NR2E3 and NRL genes in Enhanced S Cone Syndrome.
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Ten new and seventeen previously reported Enhanced S Cone Syndrome (ESCS) subjects were used to search for genetic heterogeneity. All subjects were diagnosed with ESCS on the basis of clinical, psychophysical and/or electroretinography testing using published criteria. Mutation analysis was performed on the NR2E3 nuclear receptor gene by single strand conformation analysis and direct sequencing, which revealed either homozygous (N=13) or compound heterozygous (N=11) mutations in 24 subjects (89%), heterozygous mutations in 2 subjects (7%) and no mutations in 1 subject (4%). Fifteen different mutations were identified, including six not previously reported. The subject (Patient A) with no detected NR2E3 mutation had features not usually associated with ESCS, in particular moderate rod photoreceptor function in peripheral retina and an abnormally thick retinal nerve fibre layer. Mutation analysis of the NRL, CRX, NR1D1 and THRB genes in this individual revealed a heterozygous one base-pair insertion in exon 2 of the NRL gene, which results in a predicted truncation of the NRL protein. Loss-of-function NRL alleles have not been described previously in humans, but since the same mutation was present in unaffected family members, it raises the possibility that the abnormal ESCS phenotype in Patient A may result from a digenic mechanism, with a heterozygous NRL mutation and a mutation in another unknown gene.
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2,339,015 |
Spectrum of PTCH mutations in Italian nevoid basal cell-carcinoma syndrome patients: identification of thirteen novel alleles.
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The nevoid basal cell carcinoma syndrome (NBCCS) is an autosomal dominant genetic disease characterized by numerous basal cell carcinomas, odontogenic keratocysts of the jaws, palmar and plantal pits, skeletal abnormalities, and calcification of the falx cerebri. The gene responsible for this syndrome is the PTCH tumor suppressor gene encoding for the sonic hedgehog receptor. In this paper, we report thirteen novel mutations identified in the first screening of NBCCS patients in Italy. Except for p.T230P and p.F505_L506delinsLR, all the other mutations are predicted to determine a premature truncation of the protein.
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2,339,016 |
Molecular analysis of SMA patients without homozygous SMN1 deletions using a new strategy for identification of SMN1 subtle mutations.
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Spinal muscular atrophy (SMA) is a common autosomal recessive disease. SMA is linked to the 5q13 locus in 95% of patients, and in at least 98% of them, the SMN1 homozygous deletion is found. Compound heterozygous patients, who have an SMN1 deletion associated with a subtle mutation, appear undeleted with the common molecular diagnostic test that detects only the homozygous absence of SMN1. In these patients, mutation screening in SMN1 is hampered by the presence of several copies of the highly homologous SMN2 gene. Here, we present a rapid and reliable strategy for detecting SMN mutations using long-range PCR, which avoids cloning and cDNA analysis. Using this method, we found 10 mutations, including five mutations never reported previously and five recurrent mutations; some of them are probably population-specific. Marker analysis of the 5q13 locus in these mutations showed common haplotypes, supporting the hypothesis of a common ancestor rather than a hot spot sequence. We also evaluate the suitability of automated SSCA and DHPLC for mutation scanning.
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2,339,017 |
[Molecular genetic findings in patients with congenital cone dysfunction. Mutations in the CNGA3, CNGB3, or GNAT2 genes].
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This study compares clinical and molecular genetic findings in patients with congenital cone dysfunction.</AbstractText>In this study 28 patients underwent a basic ophthalmologic examination. Except for a 1-year-old boy, color vision, perimetry, and full-field ERG (ISCEV standard) were evaluated in all patients. Blood samples were taken for molecular genetic analysis of the CNGA3, CNGB3, or GNAT2 genes.</AbstractText>Two patient groups could be distinguished: patients without and with residual cone function in the ERG. In 14 of 17 patients without cone function, mutations in one of the three genes were detected, and except for one patient mutations in both alleles could be determined. In these patients, visual acuity was reduced to 20/400 and color discrimination was absent. In 2 of 11 patients with residual cone function, mutations in one allele of the CNGB3 gene were detected. It is of interest that 6 of 16 patients with mutations perceived their disease as progressive; in three of them we could determine a progression. Only in 4 of 16 patients was the ocular fundus normal. The other patients with mutations presented with central pigment irregularities, attenuated vessels, or pale optic disk.</AbstractText>In patients with congenital cone dysfunction without cone function in the ERG, an analysis of the CNGA3, CNGB3, or GNAT2 gene is advisable. In contrast, patients with residual cone function did not show clear association with mutations in one of the three genes. In patients with mutations, retinal alterations and nystagmus are frequent. In contrast to the designation of these disorders as stationary, in some patients with mutations in the CNGA3 and CNGB3 gene slow progression was observed.</AbstractText>
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2,339,018 |
The prediction of disease risk in genomic medicine.
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Scientific prospects and implications for public policy and ethics
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2,339,019 |
Pituitary hypoplasia and respiratory distress syndrome in Prop1 knockout mice.
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Mutations in Prophet of PIT1 (Prop1), one of several homeodomain transcription factors that are required for the development of the anterior pituitary gland, are the predominant cause of MPHD (multiple pituitary hormone deficiency) in humans. We show that deletion of Prop1 in mice causes severe pituitary hypoplasia with failure of the entire Pit1 lineage and delayed gonadotrope development. The pituitary hormone deficiencies cause secondary endocrine problems and a high rate of perinatal mortality due to respiratory distress. Lung atelectasis in mutants correlates with reduced levels of NKX2.1 and surfactant. Lethality of mice homozygous for either the null allele or a spontaneous hypomorphic allele is strongly influenced by genetic background. Prop1-null mice are an excellent model for MPHD and may be useful for testing the efficacy of pharmaceutical intervention for neonatal respiratory distress.
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2,339,020 |
Secondary verbal memory: a potential endophenotype of schizophrenia.
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This study aimed at identifying neuropsychological endophenotypes of schizophrenia which met the criteria of stability and sensitivity. Twenty-six non-schizophrenic first-degree relatives together with their affected family members (all simplex-families) underwent assessment with a comprehensive neuropsychological test battery both at baseline and 13 months follow-up. Follow-up patients were in a state of stable remission. Further, 21 unrelated, demographically balanced, non-vulnerable controls were tested one at a time. A principal components analysis of our test battery resulted in four factors: (1) Vigilance, attention, and psychomotor, (2) secondary verbal memory, (3) immediate and working memory, and (3) abstraction and problem solving. At baseline testing our study revealed a pattern of selective cognitive deficits in the relative group that is less pronounced, yet qualitatively similar, to that found in the patient sample. The most severe deficits displayed both the patients and their relatives in the secondary verbal memory domain. The dysfunctions in secondary verbal memory at baseline testing significantly correlated with negative symptoms only. Secondary verbal memory deficits proved to be relatively independent of age at onset of illness, illness duration, and neuroleptic dosage. Longitudinally, dysfunctions in the patients' secondary verbal memory fluctuated over time and with negative symptoms, and persisted in remitted patients at the same level as in their relatives. In conclusion, the secondary verbal memory met the criteria of relative stability and sensitivity in our sample of simplex-families. Thus, the secondary verbal memory seems to be a potential endophenotypic marker of schizophrenia, even for cases with a hypothetically lower genetic loading.
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2,339,021 |
[Population-genetic structure of beaver (Castor fiber L., 1758) communities and estimation of effective reproductive size Ne of an elementary population].
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The absence of panmixia at all hierarchical levels of the European beaver communities down to individual families implies a complex organization of the population-genetic structures of the species, in particular, a large intergroup component of gene diversity in the populations. Testing this assumption by analysis of 39 allozyme loci in the communities of reintroduced beaver from the Vyatka river basin (Kirov oblast) has shown that only the beaver colonies exhibit high intergroup gene diversity (Gst = 0.32) whereas this parameter is much lower when estimated among beaver groups from individual Vyatka River tributaries and among localities of one of the tributaries (0.07 and 0.11, respectively). The data suggesting genetic heterogeneity among individual settles within colonies have been obtained. The factors affecting the structure of the beaver communities of the lower hierarchical ranks are considered: the common origin, founder effect, selection, gene drift, assortative mating, and social and behavior features of the species. The conclusion is drawn that the founder effect could be the primary factor of population differentiation only at the time of their formation. The heterogeneity among colonies and among settles is maintained largely by isolation of colonies from one another. The strong interspecific competition for food resources, which is behaviorally implemented in the species at the level of minimal structural units (individual settles) creates a profound and unique population-genetic subdivision of the species. These results substantiate the suggestion that an elementary population (micropopulation) of European beaver is a colony, i.e., a set of related settles of different types. Based on ecological and genetic parameters, the effective reproductive size Ne of the minimum beaver population was estimated to be equal to three animals. This extremely low value of effective reproductive population size largely explains the high tolerance of European beaver to inbreeding and striking viability of the species, which from the early 19th century has been for more than hundred years on the brink of survival in the condition which would made any other mammalian species vanish from the Earth.
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2,339,022 |
[Hereditary liver diseases].
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In recent years the identification and characterization of gene defects underlying hereditary liver diseases lead to a better understanding of their pathogenesis. Heditary hemochromatosis, Wilson's disease and alpha1-antitrypsin deficiency are the most common hereditary liver diseases. While gene defects and disease manifestation may correlate, genetic testing is generally not contributing to diagnosis. This review summarizes the clinical manifestations, diagnosis and therapy of the most frequent hereditary liver diseases: hereditary hemochromatosis, Wilson's disease and alpha1-antitrypsin deficiency.
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2,339,023 |
A novel hepatitis B virus genotyping system by using restriction fragment length polymorphism patterns of S gene amplicons.
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Traditional hepatitis B virus (HBV) genotyping methods using restriction fragment length polymorphism (RFLP) can reliably identify genotypes A to F. As HBV genotypes G and H have been recently identified, this study was to establish an accurate and simple genotyping method for all eight HBV genotypes (A to H).</AbstractText>Two hundred and forty HBV small S sequences obtained from GeneBank were analysed for restriction enzyme sites that would be genotype-specific. Restriction patterns following digestion with restriction enzymes BsrI, StyI, DpnI, HpaII, and EaeI, were determined to identify all eight HBV genotypes. Mixed genotype infections were confirmed by cloning and further RFLP analysis.</AbstractText>The new genotyping method could identify HBV genotypes A to H. Genotypes B and C could be determined by a single step digestion with BsrI and StyI in parallel. This was particularly useful in the Far East where genotypes B and C are predominant. Serum samples from 187 Chinese HBV carriers were analysed with this genotyping system, and the genotype distribution was 1.1% (2), 51.9% (97), 40.6% (76) and 4.8% (9) for genotypes A, B, C, and D, respectively. Mixed genotypes were found in only 3 patients (1.6%). Sequence data analysis confirmed the validity of this new method.</AbstractText>This HBV genotyping system can identify all eight HBV genotypes. It is accurate and simple, and can be widely used for studies on HBV genotyping.</AbstractText>
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2,339,024 |
Zebrafish and fly Nkx6 proteins have similar CNS expression patterns and regulate motoneuron formation.
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Genes belonging to the Nkx, Gsh and Msx families are expressed in similar dorsovental spatial domains of the insect and vertebrate central nervous system (CNS), suggesting the bilaterian ancestor used this genetic program during CNS development. We have investigated the significance of these similar expression patterns by testing whether Nkx6 proteins expressed in ventral CNS of zebrafish and flies have similar functions. In zebrafish, Nkx6.1 is expressed in early-born primary and later-born secondary motoneurons. In the absence of Nkx6.1, there are fewer secondary motoneurons and supernumerary ventral interneurons, suggesting Nkx6.1 promotes motoneuron and suppresses interneuron formation. Overexpression of fish or fly Nkx6 is sufficient to generate supernumerary motoneurons in both zebrafish and flies. These results suggest that one ancestral function of Nkx6 proteins was to promote motoneuron development.
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2,339,025 |
Ethical issues in identifying and recruiting participants for familial genetic research.
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Family-based research is essential to understanding the genetic and environmental etiology of human disease. The success of family-based research often depends on investigators' ability to identify, recruit, and achieve a high participation rate among eligible family members. However, recruitment of family members raises ethical concerns due to the tension between protecting participants' privacy and promoting research quality, and guidelines for these activities are not well established. The Cancer Genetics Network Bioethics Committee assembled a multidisciplinary group to explore the scientific and ethical issues that arise in the process of family-based recruitment. The group used a literature review as well as expert opinion to develop recommendations about appropriate approaches to identifying, contacting, and recruiting family members. We conclude that there is no single correct approach, but recommend a balanced approach that takes into account the nature of the particular study as well as its recruitment goals. Recruitment of family members should be viewed as part of the research protocol and should require appropriate informed consent of the already-enrolled participant. Investigators should inform prospective participants why they are being contacted, how information about them was obtained, and what will happen to that information if they decide not to participate. The recruitment process should also be sensitive to the fact that some individuals from families at increased genetic risk will have no prior knowledge of their risk status. These recommendations are put forward to promote further discussion about the advantages and disadvantages of various approaches to family-based recruitment. They suggest a framework for considering alternative recruitment strategies and their implications, as well as highlight areas in need of further empirical research.
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2,339,026 |
Selecting appropriate animal models and experimental designs for endocrine disruptor research and testing studies.
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Evidence that chemicals in the environment may cause developmental and reproductive abnormalities in fish and wildlife by disrupting normal endocrine functions has increased concern about potential adverse human health effects from such chemicals. US laws have now been enacted that require the US Environmental Protection Agency (EPA) to develop and validate a screening program to identify chemicals in food and water with potential endocrine-disrupting activity. EPA subsequently proposed an Endocrine Disruptor Screening Program that uses in vitro and in vivo test systems to identify chemicals that may adversely affect humans and ecologically important animal species. However, the endocrine system can be readily modulated by many experimental factors, including diet and the genetic background of the selected animal strain or stock. It is therefore desirable to minimize or avoid factors that cause or contribute to experimental variation in endocrine disruptor research and testing studies. Standard laboratory animal diets contain high and variable levels of phytoestrogens, which can modulate physiologic and behavioral responses similar to both endogenous estrogen as well as exogenous estrogenic chemicals. Other studies have determined that some commonly used outbred mice and rats are less responsive to estrogenic substances than certain inbred mouse and rat strains for various estrogen-sensitive endpoints. It is therefore critical to select appropriate biological models and diets for endocrine disruptor studies that provide optimal sensitivity and specificity to accomplish the research or testing objectives. An introduction is provided to 11 other papers in this issue that review these and other important laboratory animal experimental design considerations in greater detail, and that review laboratory animal and in vitro models currently being used or evaluated for endocrine disruptor research and testing. Selection of appropriate animal models and experimental design parameters for endocrine disruptor research and testing will minimize confounding experimental variables, increase the likelihood of replicable experimental results, and contribute to more reliable and relevant test systems.
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2,339,027 |
Estimating the degree of saturation in mutant screens.
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Large-scale screens for loss-of-function mutants have played a significant role in recent advances in developmental biology and other fields. In such mutant screens, it is desirable to estimate the degree of "saturation" of the screen (i.e., what fraction of the possible target genes has been identified). We applied Bayesian and maximum-likelihood methods for estimating the number of loci remaining undetected in large-scale screens and produced credibility intervals to assess the uncertainty of these estimates. Since different loci may mutate to alleles with detectable phenotypes at different rates, we also incorporated variation in the degree of mutability among genes, using either gamma-distributed mutation rates or multiple discrete mutation rate classes. We examined eight published data sets from large-scale mutant screens and found that credibility intervals are much broader than implied by previous assumptions about the degree of saturation of screens. The likelihood methods presented here are a significantly better fit to data from published experiments than estimates based on the Poisson distribution, which implicitly assumes a single mutation rate for all loci. The results are reasonably robust to different models of variation in the mutability of genes. We tested our methods against mutant allele data from a region of the Drosophila melanogaster genome for which there is an independent genomics-based estimate of the number of undetected loci and found that the number of such loci falls within the predicted credibility interval for our models. The methods we have developed may also be useful for estimating the degree of saturation in other types of genetic screens in addition to classical screens for simple loss-of-function mutants, including genetic modifier screens and screens for protein-protein interactions using the yeast two-hybrid method.
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2,339,028 |
A genetic screen for dominant modifiers of a cyclin E hypomorphic mutation identifies novel regulators of S-phase entry in Drosophila.
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Cyclin E together with its kinase partner Cdk2 is a critical regulator of entry into S phase. To identify novel genes that regulate the G1- to S-phase transition within a whole animal we made use of a hypomorphic cyclin E mutation, DmcycEJP, which results in a rough eye phenotype. We screened the X and third chromosome deficiencies, tested candidate genes, and carried out a genetic screen of 55,000 EMS or X-ray-mutagenized flies for second or third chromosome mutations that dominantly modified the DmcycEJP rough eye phenotype. We have focused on the DmcycEJP suppressors, S(DmcycEJP), to identify novel negative regulators of S-phase entry. There are 18 suppressor gene groups with more than one allele and several genes that are represented by only a single allele. All S(DmcycEJP) tested suppress the DmcycEJP rough eye phenotype by increasing the number of S phases in the postmorphogenetic furrow S-phase band. By testing candidates we have identified several modifier genes from the mutagenic screen as well as from the deficiency screen. DmcycEJP suppressor genes fall into the classes of: (1) chromatin remodeling or transcription factors; (2) signaling pathways; and (3) cytoskeletal, (4) cell adhesion, and (5) cytoarchitectural tumor suppressors. The cytoarchitectural tumor suppressors include scribble, lethal-2-giant-larvae (lgl), and discs-large (dlg), loss of function of which leads to neoplastic tumors and disruption of apical-basal cell polarity. We further explored the genetic interactions of scribble with S(DmcycEJP) genes and show that hypomorphic scribble mutants exhibit genetic interactions with lgl, scab (alphaPS3-integrin--cell adhesion), phyllopod (signaling), dEB1 (microtubule-binding protein--cytoskeletal), and moira (chromatin remodeling). These interactions of the cytoarchitectural suppressor gene, scribble, with cell adhesion, signaling, cytoskeletal, and chromatin remodeling genes, suggest that these genes may act in a common pathway to negatively regulate cyclin E or S-phase entry.
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2,339,029 |
A screen for genes that interact with the Drosophila pair-rule segmentation gene fushi tarazu.
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The pair-rule gene fushi tarazu (ftz) of Drosophila is expressed at the blastoderm stage in seven stripes that serve to define the even-numbered parasegments. ftz encodes a DNA-binding homeodomain protein and is known to regulate genes of the segment polarity, homeotic, and pair-rule classes. Despite intensive analysis in a number of laboratories, how ftz is regulated and how it controls its targets are still poorly understood. To help understand these processes, we conducted a screen to identify dominant mutations that enhance the lethality of a ftz temperature-sensitive mutant. Twenty-six enhancers were isolated, which define 21 genes. All but one of the mutations recovered show a maternal effect in their interaction with ftz. Three of the enhancers proved to be alleles of the known ftz protein cofactor gene ftz-f1, demonstrating the efficacy of the screen. Four enhancers are alleles of Atrophin (Atro), the Drosophila homolog of the human gene responsible for the neurodegenerative disease dentatorubral-pallidoluysian atrophy. Embryos from Atro mutant germ-line mothers lack the even-numbered (ftz-dependent) engrailed stripes and show strong ftz-like segmentation defects. These defects likely result from a reduction in Even-skipped (Eve) repression ability, as Atro has been shown to function as a corepressor for Eve. In this study, we present evidence that Atro is also a member of the trithorax group (trxG) of Hox gene regulators. Atro appears to be particularly closely related in function to the trxG gene osa, which encodes a component of the brahma chromatin remodeling complex. One additional gene was identified that causes pair-rule segmentation defects in embryos from homozygous mutant germ-line mothers. The single allele of this gene, called bek, also causes nuclear abnormalities similar to those caused by alleles of the Trithorax-like gene, which encodes the GAGA factor.
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2,339,030 |
An efficient Monte Carlo approach to assessing statistical significance in genomic studies.
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Multiple hypothesis testing is a common problem in genome research, particularly in microarray experiments and genomewide association studies. Failure to account for the effects of multiple comparisons would result in an abundance of false positive results. The Bonferroni correction and Holm's step-down procedure are overly conservative, whereas the permutation test is time-consuming and is restricted to simple problems.</AbstractText>We developed an efficient Monte Carlo approach to approximating the joint distribution of the test statistics along the genome. We then used the Monte Carlo distribution to evaluate the commonly used criteria for error control, such as familywise error rates and positive false discovery rates. This approach is applicable to any data structures and test statistics. Applications to simulated and real data demonstrate that the proposed approach provides accurate error control, and can be substantially more powerful than the Bonferroni and Holm methods, especially when the test statistics are highly correlated.</AbstractText>
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2,339,031 |
Genetic screening, health care and the insurance industry. Should genetic information be made available to insurers?
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The potential use of genetic tests in insurance has raised concerns about discrimination and individuals losing access to health care either because of refusals to test for treatable diseases, or because test-positives cannot afford premiums. Governments have so far largely sought to restrict the use of genetic information by insurance companies. To date the number of tests available with significant actuarial value is limited. However, this is likely to change, raising more clearly the question as to whether the social costs of adverse selection outweigh the social costs of individuals not accessing health care for fear of the consequences of test information being used in insurance markets. In this contribution we set out the policy context and model the potential trade-offs between the losses faced by insurers from adverse selection by insurees (which will increase premiums reducing consumer welfare) and the detrimental health effects that may result from persons refusing to undergo tests that could identify treatable health conditions. It argues that the optimal public policy on genetic testing should reflect overall societal benefit, taking account of these trade-offs. Based on our model, the factors that influence the outcome include: the size of and value attached to the health gains from treatment; deterrent effects of a disclosure requirement on testing for health reasons; incidence of the disease; propensity of test-positives to adverse select; policy value adverse selectors buy in a non-disclosure environment; and price elasticity of demand for insurance. Our illustrative model can be used as a benchmark for developing other scenarios or incorporating real data in order to address the impact of different policies on disclosure and requirement to test.
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2,339,032 |
Mutations in the gene coding for guanylate cyclase-activating protein 2 (GUCA1B gene) in patients with autosomal dominant retinal dystrophies.
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We investigated mutations in the gene coding for guanylate-cyclase activating protein 2 (GCAP2), also known as GUCA1B gene, in Japanese patients with retinitis pigmentosa (RP) and tried to identify phenotypic characteristics associated with mutations in the gene.</AbstractText>Genomic DNA samples from 63 unrelated patients with autosomal dominant retinitis pigmentosa (ADRP) and 33 patients with autosomal recessive retinitis pigmentosa (ARRP) were screened by single-strand conformational polymorphism analysis followed by direct sequencing. Clinical features associated with a mutation were demonstrated by visual acuity, visual field testing, fundus photography, and electroretinography.</AbstractText>A novel transitional mutation converting GGA to AGA at codon 157 (G157R) was identified. This mutation has been found in three index patients from three independent families. Phenotypic examination of seven members of the three families revealed that this mutation was associated with RP with or without macular involvement in five members, macular degeneration in one member, and asymptomatic normal phenotype in one member. In addition, previously unknown polymorphic changes including V29V, Y57Y, T87I, and L180L were identified.</AbstractText>A racial difference exists in the spectrum of mutations and/or polymorphisms in the GCAP 2 gene between British and Japanese populations. Our findings suggest that the mutation in the GCAP 2 gene can cause one form of autosomal dominant retinal dystrophy, with variable phenotypic expression and incomplete penetrance.</AbstractText>
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2,339,033 |
Association analysis of mild mental impairment using DNA pooling to screen 432 brain-expressed single-nucleotide polymorphisms.
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We hypothesize that mild mental impairment (MMI) represents the low extreme of the same quantitative trait loci (QTLs) that operate throughout the distribution of intelligence. To detect QTLs of small effect size, we employed a direct association strategy by genotyping 432 presumably functional nonsynonymous single-nucleotide polymorphisms (nsSNPs) identified from public databases on DNA pools of 288 cases and 1025 controls. In total, 288 MMI cases were identified by in-home administration of McCarthy Scales of Children's Abilities to 836 twin pairs selected from a community sample of more than 14 000 children previously screened for nonverbal cognitive delay using parentally administered tests. Controls were selected from the community sample representing the full range of nonverbal intelligence. SNPs showing at least 7% allele frequency differences between case and control DNA pools were tested for their association with the full range of nonverbal intelligence using five DNA subpools, each representing quintiles of the normal quantitative trait scores from the 1025 controls. SNPs showing linear associations in the expected direction across quintiles using pooled DNA were individually genotyped for the 288 cases and 1025 controls and analyzed using standard statistical methods. One SNP (rs1136141) in HSPA8 met these criteria, yielding a significant (P=0.036) allelic frequency difference between cases and controls for individual genotyping and a significant (P=0.013) correlation within the control group that accounts for 0.5% of the variance. The present SNP strategy combined with DNA pooling and large samples represents a step towards identifying QTLs of small effect size associated with complex traits in the postgenomic era when all functional polymorphisms will be known.
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2,339,034 |
Colon cancer screening practices following genetic testing for hereditary nonpolyposis colon cancer (HNPCC) mutations.
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Although increased colonoscopic surveillance is recommended for hereditary nonpolyposis colon cancer (HNPCC) mutation carriers, limited information is available on adherence to colorectal cancer screening recommendations. This study investigated colonoscopy practices following genetic testing for HNPCC mutations.</AbstractText>This prospective cohort study was conducted between May 22, 1996, and November 13, 1999. Participants were 98 men and women without a personal history of colon cancer or colectomy who were identified from 11 extended HNPCC families. Colonoscopy use was evaluated by telephone before genetic counseling and was reassessed 1, 6, and 12 months following test results disclosure.</AbstractText>During the 12 months following genetic counseling and testing, 73% (16/22) of HNPCC mutation carriers, 16% (8/49) of noncarriers, and 22% (6/27) of decliners reported having a colonoscopy (chi(2) = 23.97, P<.001). After controlling for clinical factors and pretest screening practices, HNPCC mutation carriers were significantly more likely than test decliners to have a colonoscopy (odds ratio [OR], 12.12; 95% confidence interval [CI], 3.42-42.96; P<.001). There were no differences in colonoscopy use between noncarriers and decliners (OR, 0.60; 95% CI, 0.28-1.29; P =.19). Perceived control over developing colon cancer also had a significant effect on posttest colonoscopy use (OR, 2.19; 95% CI, 1.22-3.94; P =.01).</AbstractText>Genetic testing may motivate increased colonoscopic screening among HNPCC mutation carriers. Increased efforts may be needed to assess patients' family histories of colon cancer and provide appropriate referrals for genetic counseling and testing to target colonoscopic screening to high-risk individuals.</AbstractText>
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2,339,035 |
Development of PCR assay based on ITS2 rDNA polymorphism for the detection and differentiation of Fusarium sporotrichioides.
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A polymerase chain reaction assay was developed for detection of Fusarium sporotrichioides, a plant pathogen in many parts of the world. Based on small nucleotide differences in ITS2 (Internal Transcribed Spacer) rDNA of our local isolate of F. sporotrichioides (Accession No. AY510069) and other isolates found in NCBI/GeneBank database, species specific primer FspITS2K was selected. Primer pair FspITS2K and P28SL amplified a fragment of 288 bp containing a portion of ITS2 and 28S rDNA of all the F. sporotrichioides isolates tested, originated from different hosts and regions of the world but did not amplify any other species of Fusarium and plant's DNA. To use the PCR assay in seed health testing, a protocol was setup for the rapid and effective preparations of fungal DNA from wheat seeds. The method developed may be useful for the rapid detection and identification of F. sporotrichioides both from culture and from plant tissue.
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2,339,036 |
Zebrafish as a neurotoxicological model.
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At a time when common regulatory pathways are being identified in several different species and genomics is beginning to allow comparisons of genes, how they are arranged on chromosomes and how they are regulated, zebrafish has emerged as a valuable and complementary vertebrate model. Some of the characteristics that prove of value are described and illustrated. Fluorescent transgenic lines of zebrafish embryos are presented for time-line studies with neurotoxicants. While genetic knockout technology has yet to be developed for the model, the anti-sense, morpholino approach allows for knockdown of expression of genes for the 3 day, embryonic period. This can provide for phenocopies of mutant genes for those genes essential to embryonic development or it can provide for a limited inhibition of gene expression that allows subsequent development of the fish. With the zebrafish genomic sequencing effort, microarray technology is now developing for the model system. These resources and technologies allow one to challenge the system with toxicants, and to view the immediate effects of the toxicants with transgenic embryos that fluoresce in part or all of the nervous system. Behavioral and learning protocols have been developed for the organism so that early exposures can be assayed for effects upon adult fish. Microarray technology should allow for one to identify specific genes and pathways affected by a neurotoxicant. In the future, these approaches should provide a working protocol for exploring molecular mechanisms of neurotoxicants. This type of complementary approach should then allow for more efficient examination and testing of mechanisms in mammalian models.
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2,339,037 |
Association between a T/C polymorphism in intron 2 of cholesterol 24S-hydroxylase gene and Alzheimer's disease in Chinese.
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A polymorphism (T/C) in intron 2 of the cholesterol 24-hydroxylase (CYP46) gene has recently been reported to be associated with the risk for late-onset Alzheimer's disease (LOAD). To investigate possible involvement of the CYP46 gene and apolipoprotein E (APOE) gene polymorphisms in the manifestation of LOAD, we analyzed 99 sporadic LOAD patients and 113 healthy controls of China. We found an obvious association between CYP46 TT genotype and LOAD (OR = 2.98, 95% CI 1.64-5.44, P < 0.001). A clear increase of the risk to develop LOAD was also observed in subjects carrying both the CYP46 TT genotype and the APOE epsilon4-allele (OR = 12.94, 95% CI 4.26-39.32, P < 0.001). Our data reveal that the polymorphism of CYP46 intron 2 is implicated in the susceptibility to LOAD and a strong synergistic interaction between CYP46 TT homozoygots and APOE epsilon4 carrier status on the risk of LOAD.
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2,339,038 |
Cancer risk assessment: quality and impact of the family history interview.
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Identification of individuals at high risk for colon and breast cancer requires an adequate family history assessment and can influence cancer screening and genetic testing decisions. Little data exist that evaluate the completeness of the family history interview in primary care.</AbstractText>Retrospective chart review of 995 new patient visits to 28 primary care physicians evaluating the completeness of the family cancer history for colon or breast cancer. Family history information was evaluated for inclusion of age at diagnosis, degree of kinship, and specification of disease of interest.</AbstractText>Family history information on cancer diagnoses was collected on 679 (68%) of the patients. Specific information regarding the individual affected and the cancer diagnosis was present in 414 (61%) of the records. Affected first-degree relatives were more likely to have their age of cancer diagnosis recorded than second-degree relatives (39%, 95% confidence interval [CI]=34%-44% vs 16%, 95% CI=12%-20%). Age at diagnosis of cancer in first-degree relatives was documented in 51% of colon cancers, 38% of breast cancers, and 27% of ovarian cancers. Only 17% of individuals who meet criteria for early-onset breast cancer genetic testing were referred for genetic services.</AbstractText>Adequate cancer risk assessment using family history information requires age at cancer diagnosis and specification of a cancer diagnosis. Age at diagnosis was frequently missing from family history assessments, which could have a potential impact on identification of high-risk individuals. When family history information does identify high-risk individuals, only the minority are referred for genetic services.</AbstractText>
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2,339,039 |
[Principle of LAMP method--a simple and rapid gene amplification method].
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So far nucleic acid test (NAT) has been employed in various fields, including infectious disease diagnoses. However, due to its complicated procedures and relatively high cost, it has not been widely utilized in many actual diagnostic applications. We have therefore developed a simple and rapid gene amplification technology, Loop-mediated Isothermal Amplification (LAMP) method, which has shown prominent results of surpassing the performance of the conventional gene amplification methods. LAMP method acquires three main features: (1) all reaction can be carried out under isothermal conditions; (2) the amplification efficiency is extremely high and tremendous amount of amplification products can be obtained; and (3) the reaction is highly specific. Furthermore, developed from the standard LAMP method, a rapid LAMP method, by adding in the loop primers, can reduce the amplification time from the previous 1 hour to less than 30 minutes. Enormous amount of white precipitate of magnesium pyrophosphate is produced as a by-product of the amplification, therefore, direct visual detection is possible without using any reaction indicators and detection equipments. We believe LAMP technology, with the integration of these features, can rightly apply to clinical genetic testing, food and environmental analysis, as well as NAT in different fields.
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2,339,040 |
Ethical implications of pharmacogenetics--do slippery slope arguments matter?
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Pharmacogenetics is a rapidly expanding area of research exploring the relationship between inter-individual genetic variation and drug response, with the goal of developing genetically optimised therapies. Slippery slope arguments claim that a particular action should be rejected (or supported) because it might be the first step onto a slippery slope leading to undesirable (or desirable) consequences. In this article, several slippery slope arguments relevant to the context of pharmacogenetics are evaluated under consideration of underlying reasons for their popularity. The author concludes that although the examined arguments are unconvincing as slippery slope arguments, they do matter in this context. While positive slippery slope arguments serve as a driving force to fuel the development of pharmacogenetics, their negative counterparts play an important role to sensitise policy makers and the public to potential problems.
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2,339,041 |
Pharmacogenetic testing, informed consent and the problem of secondary information.
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Numerous benefits for patients have been predicted if prescribing decisions were routinely accompanied by pharmacogenetic testing. So far, little attention has been paid to the possibility that the routine application of this new technology could result in considerable harm to patients. This article emphasises that pharmacogenetic testing shares both the opportunities and the pitfalls with 'conventional' disease-genetic testing. It demonstrates that performing pharmacogenetic tests as well as interpreting the results are extraordinarily complex issues requiring a high level of expertise. It further argues that pharmacogenetic testing can have a huge impact on clinical decisions and may influence the therapeutic strategy as well as the clinical monitoring of a patient. This view challenges the predominant paradigm that pharmacogenetic testing will predict patients' responses to medicines, but that it will not provide any other significant disease-specific predictive information about the patient or family members. The article also questions published proposals to reduce the consent procedure for pharmacogenetic testing to a simple statement that the physician wishes to test a sample of the patient's DNA to see if a drug will be safe or whether it will work, and presents an alternative model that is better suited to protect patient's interests and to obtain meaningful informed consent. The paper concludes by outlining conditions for the application of pharmacogenetic testing in clinical practice in a way that can make full use of its potential benefits while minimising possible harm to patients and their families.
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2,339,042 |
Malignant hyperthermia in North America: genetic screening of the three hot spots in the type I ryanodine receptor gene.
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Malignant hyperthermia (MH) is a pharmacogenetic disorder of skeletal muscle, manifested as a life-threatening hypermetabolic crisis after exposure to anesthetics. Type I ryanodine receptor 1 is the primary gene responsible for susceptibility to MH as well as central core disease, a congenital myopathy that predisposes susceptibility to MH. More than 40 mutations in the RyR1 gene cluster in three coding regions: the N-terminus, central, and C-terminus regions. However, the frequency of mutations in each region has not been studied in the North American MH-susceptible population.</AbstractText>The authors tested 124 unrelated patients with MH susceptibility for the presence of mutations in the N-terminus (exons 2, 6, 9, 11, 12, and 17), central (exons 39, 40, 44, 45, and 46), and C-terminus (exons 95, 100, 101, and 102) regions.</AbstractText>Fourteen mutations have been identified in 29 of 124 MH-susceptible patients (23%). Approximately 70% of the mutations, which include a novel mutation, Ala 2437Val, were in the central region. In 8 patients (28%), mutations were identified in the N-terminus region. Screening the C-terminus region yielded a novel mutation, Leu4824Pro, in a single patient with a diagnosis of central core disease.</AbstractText>The detection rate for mutations is only 23% by screening mutations (or exons) listed in the 2002 North American consensus panel. The implications from this study suggest that testing the central region first is currently the most effective screening strategy for the North American population. Screening more exons in the three hot spots may be needed to find an accurate frequency of mutations in the RyR1 gene.</AbstractText>
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2,339,043 |
Production of gametangia by Phytophthora ramorum in vitro.
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Until now gametangia have not been obtained between paired European A1 and American A2 isolates of Phytopthora ramorum in vitro. Their production in artificial culture relies on interspecific pairings. Using P. drechsleri and P. cambivora testers, 51 of 110 P. ramorum isolates from across Europe were all shown to be A1s; while 32 of 38 American isolates from across California and southwest Oregon were shown to be A2s. However, these interspecific pairings are complex, unusually slow and unpredictable. A range of culture media and conditions are described that were tested, unsuccessfully, with a view to enhancing the efficiency of the interspecific pairings. In further tests, gametangia were obtained between A1 and A2 isolates of P. ramorum when juvenile, pre-chlamydospore producing mycelia were mixed together on carrot agar. The gametangia formed in 3-10 d, sparsely to frequently, initially only within the boundaries of the mixed inocula but subsequently in the extended mycelial growth. Chlamydospores were also produced. This inoculum-mixing method, though again sometimes unpredictable, should enhance efficiency of testing for compatibility types and facilitate further studies on whether the sexual outcrossing system of P. ramorum is functional. Differences between sexual reproduction of P. ramorum and that of other heterothallic Phytophthora species are discussed.
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2,339,044 |
North American populations of Entoleuca mammata are genetically more variable than populations in Europe.
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Entoleuca mammata (syn. Hypoxylon mammatum) is a damaging pathogen of Populus tremuloides and P. grandidentata in North America and P. tremula in Europe, where the fungus occurs only sporadically in alpine regions and Scandinavia. It has been hypothesized that E. mammata was introduced to Europe from North America. In this study, E. mammata isolates collected from Europe and North America were compared by a sequence analysis of two DNA markers derived from DNA fingerprints. The objective of the study was to elucidate the relationship between North American and European E. mammata populations by testing two hypotheses: (1) North American and European isolates are conspecific; and (2) the fungus was introduced between continents causing both a founder effect and a genetic bottleneck. North American populations were found to be more polymorphic, but no major phylogenetic differences between fungal isolates collected from different continents were found. This result combined with the historical observations of the disease in Europe implies that E. mammata was introduced to Europe several centuries ago.
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2,339,045 |
Mechanisms of sperm competition: testing the fair raffle.
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Sperm competition is a major force of sexual selection, but its implications for mating system and life-history evolution are just beginning to be understood. Of particular importance is understanding the mechanisms of sperm competition. Models have been developed to determine if sperm competition operates in a fair raffle process, whereby each sperm from competing males has an equal chance of fertilizing a female's ova, or if it operates in a loaded raffle process, whereby one male's sperm has a fertilization advantage. These models require data on relative sperm and offspring (paternity) numbers of competing males. Here we develop a model based on maximum-likelihood methods for differentiating between the fair and loaded raffle processes. The model calculates the relative competitiveness of two males' sperm (loadings) as well as the economy of scale (nonlinear returns to sperm number). Previous models implicitly assumed that there is no economy of scale, which may not be the case when there is cooperation or interference among sperm from a given male. We demonstrate that our model has superior power-in some instances more than double-than previous models. We apply our model to an example of sperm competition in the guppy (Poecilia reticulata) and show that the system may be characterized by a loaded raffle attributable to effects of second male precedence.
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2,339,046 |
A likelihood-based approach to estimating and testing for isolation by distance.
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Simple regression of genetic similarities between pairs of populations on their corresponding geographic distances is frequently used to detect the presence of isolation by distance (IBD). However, these pairwise values are obviously not independent and there is no parametric procedure for estimating and testing for the IBD intercepts and slopes based on standard regression theory. Nonparametric tests, such as the Mantel test, and resampling techniques, such as bootstrapping, have been exploited with limited success. Here, I describe a likelihood-based analysis to allow for simultaneously detecting patterns of correlated residuals and estimating and testing for the presence of IBD. It is shown, through the analysis of two molecular datasets in pine species, that different covariance structures of the residuals exist. More over, the likelihood ratio tests under these covariance structures are less sensitive to the presence of IBD than the Mantel test and the simple regression analysis but more sensitive than the bootstrap and jackknife samples over independent populations or population pairs. Because the likelihood analysis directly models and accounts for nonindependence of residuals, it should legitimately detect the presence of IBD, thereby allowing for accurate inferences about evolutionary and demographic processes influencing the extent and patterns of IBD.
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2,339,047 |
A novel family with an unusual early-onset generalized dystonia.
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We report on an Italian family in which three brothers and their maternal grandfather had a generalized early-onset dystonia with mild parkinsonian signs. Genetic testing excluded the rapid-onset dystonia-parkinsonism locus (DYT12; OMIM*128235), autosomal recessive Parkin locus (PARK2; OMIM *602544), and DYT1 dystonia. Three affected siblings were found to share an identical haplotype at the X-linked dystonia-parkinsonism locus (XDP; Lubag; OMIM*314250). This haplotype differed from the haplotype observed in Filipino patients, ruling out the hypothesis of a common underlying mutation. In addition, direct sequencing analysis of the putative disease causing changes observed in Filipino patients were not found in the Italian patients. The condition we describe could be a newly recognized dystonia syndrome with parkinsonism.
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2,339,048 |
Bounds and normalization of the composite linkage disequilibrium coefficient.
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The composite linkage disequilibrium (LD) measure is often calculated for two-locus genotypic data, especially when coupling and repulsion double heterozygotes cannot be distinguished. This measure was reported to have good statistical properties and was suggested for routine testing of LD, regardless of Hardy-Weinberg equilibrium at either of two loci. However, the bounds for this measure have not been yet reported. These bounds are derived here as functions of one-locus genotype or allele frequencies. They provide standardized measures of composite linkage disequilibrium, defined as the proportion of its maximum attainable value, given observed allele or genotype frequencies.
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2,339,049 |
Women's satisfaction with genetic counseling for hereditary breast-ovarian cancer: psychological aspects.
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Women who participate in BRCA1/2 cancer genetic counseling do so for a variety of reasons, including learning quantitative risk information about their chances of developing hereditary breast-ovarian cancer at some point during their lifetimes. For these women, obtaining pre-test and disclosure genetic counseling with a professional affords them numerous potential benefits, including adequate preparation for, and accurate interpretation of, their test results. In consequence, women commonly report being highly satisfied with their cancer genetic counseling experience, even if the information learned through testing suggests they are at increased cancer risk. This occurrence raises an interesting question, namely, what are the psychological aspects of satisfaction with genetic counseling for hereditary breast-ovarian cancer in women? To answer this question, we administered the Genetic Counseling Satisfaction Scale (GCSS) to a convenience sample of 61 women participating in BRCA1/2 pretest genetic counseling, and re-administered the GCSS to approximately one-third of these women at disclosure. Available psychological data included personality, distress, and family functioning. In bivariate analyses, optimism and family functioning were positively associated with pretest satisfaction. With respect to satisfaction at disclosure, general and cancer-specific distress were negatively associated with satisfaction. Our findings suggest that psychological aspects of satisfaction with cancer genetic counseling vary, with individual differences and family functioning playing a role at pretest, and distress playing a role at disclosure. The implications for future research and clinical practice are discussed.
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2,339,050 |
Analysis of factor VIII gene intron 1 inversion in Argentinian families with severe haemophilia A and a review of the literature.
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Besides intron 22 factor VIII gene inversion (Inv22), intron 1 inversion (Inv1) has recently been reported as a further recurrent mutation that causes approximately 5% of severe haemophilia A (HA) cases. We analysed the presence of the Inv1 in a group of 64 severe HA-affected families from Argentina, and found only one positive case. This Inv1 patient has not developed a factor VIII inhibitor, and the screening for small mutations in the coding sequences of the factor VIII gene did not detect any additional defect in this case. The Inv1 genotyping was further applied to analyse the haemophilia carrier status of the proband's sister. In addition, we studied the accuracy of the current polymerase chain reaction-based method to investigate the Inv1, and confirmed the absence of amplimer length polymorphisms associated to the Inv1-specific polymerase chain reaction amplifications in 101 X-chromosome haplotypes from unrelated Argentinian healthy males. In order to discuss Inv1 mutation frequency in severe HA and the risk of inhibitor formation, a review of the literature was included. Our data highlight the importance of analysis of the Inv1 in Inv22-negative severe HA cases. This will benefit both genetic counselling and the study of the relationship between genotype and inhibitor development.
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2,339,051 |
Analysis of microsatellites and parentage testing in saltwater crocodiles.
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Fifteen microsatellite loci were evaluated in farmed saltwater crocodiles for use in parentage testing. One marker (C391) could not be amplied. For the remaining 14, the number of alleles per locus ranged from two to 16, and the observed heterozygosities ranged from 0.219 to 0.875. The cumulative exclusion probability for all 14 loci was .9988. the 11 loci that showed the greatest level of polymorphism were used for parentage testing, with an exclusion probability of .9980. With these 11 markers on 107 juveniles from 16 known breeding pairs, a 5.6% pedigree error rate was detected. This level of pedigree error, if consistent, could have an impact on the accuracy of gentic parameter and breeding value estimation. The usefulness of these markers was also evaluated for assigning parentage in situations where maternity, paternity, or both may not be known. In these situations, a 2% error in parentage assignment was predicted. It is therefore recommended that more micro-satellite markers be used in these situations. The use of these microsatellite markers will broaden the scope of a breeding program, allowing progeny to be tested from adults maintained in large breeding lagoons for selection as future breeding animals.
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2,339,052 |
Understanding human DNA sequence variation.
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Over the past century researchers have identified normal genetic variation and studied that variation in diverse human populations to determine the amounts and distributions of that variation. That information is being used to develop an understanding of the demographic histories of the different populations and the species as a whole, among other studies. With the advent of DNA-based markers in the last quarter century, these studies have accelerated. One of the challenges for the next century is to understand that variation. One component of that understanding will be population genetics. We present here examples of many of the ways these new data can be analyzed from a population perspective using results from our laboratory on multiple individual DNA-based polymorphisms, many clustered in haplotypes, studied in multiple populations representing all major geographic regions of the world. These data support an "out of Africa" hypothesis for human dispersal around the world and begin to refine the understanding of population structures and genetic relationships. We are also developing baseline information against which we can compare findings at different loci to aid in the identification of loci subject, now and in the past, to selection (directional or balancing). We do not yet have a comprehensive understanding of the extensive variation in the human genome, but some of that understanding is coming from population genetics.
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2,339,053 |
Regulatory approaches to reproductive genetic testing.
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This report analyses the ethical and legal aspects of reproductive genetic testing in 11 countries (Australia, Austria, Canada, France, Germany, India, Israel, Japan, The Netherlands, Switzerland and the UK). The legal status of reproductive genetic testing in the countries under analysis is difficult to generalize due to the different regulatory systems adopted. These approaches are a reflection of the legal traditions and cultural and socio-religious beliefs which inform and shape public policy on assisted reproductive technologies and genetic testing. We divide approaches into two groups: public ordering (legislative, top-down approach) and private ordering (non-legislative, bottom-up approach). Even limiting our analysis to a number of countries that span the range from restrictive to pragmatic approaches, there is remarkable symmetry in both the (i) substantive requirements (i.e. gravity, health indications generally) and (ii) procedural safeguards (i.e. informed consent, counselling, confidentiality, civil status, oversight and accreditation) surrounding reproductive genetic testing. Indeed, irrespective of whether a country adopts a prohibitive or a permissive approach through legislation or self-regulation or a mix of both, the ultimate decision is--and should continue to be--a medical one. Nowhere is this more evident than in the substantive requirements.
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2,339,054 |
HPLC retention time as a diagnostic tool for hemoglobin variants and hemoglobinopathies: a study of 60000 samples in a clinical diagnostic laboratory.
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Previous evaluations of HPLC as a tool for detection of hemoglobin variants have done so within newborn-screening programs and/or by use of stored samples. We describe a 32-month prospective study in a clinical diagnostic laboratory in which we evaluated the imprecision of HPLC retention times and determined the retention times for hemoglobin variants seen in a multiethnic setting.</AbstractText>We analyzed all samples on the Bio-Rad Variant II HPLC system. For normal hemoglobin fractions and hemoglobin variants, we recorded and analyzed their retention times, their proportion of the total hemoglobin (%), and the peak characteristics. We compared the imprecision of retention time with the imprecision of retention time normalized to the retention time of hemoglobin A0 (Hb A0) and to the retention time of Hb A2. Alkaline and acid hemoglobin electrophoresis, and in certain cases globin chain electrophoresis, isoelectric focusing, and DNA analysis, were performed to document the identities of the hemoglobin variants.</AbstractText>The mean (SD) imprecision (CV) of the retention time was 1.0 (0.7)% with no statistical difference compared with the imprecision for normalized retention times. Among 60,293 samples tested, we encountered 34 unique hemoglobin variants and 2 tetramers. Eighteen variants and 2 tetramers could be identified solely by retention time and 3 variants by retention time and proportion of total hemoglobin. Four variants could be identified by retention time and peak characteristics and eight variants by retention time and electrophoretic mobility. One variant (Hb New York) was missed on HPLC. Retention time on HPLC was superior to electrophoresis for the differentiation and identification of six members of the Hb J family, four members of the Hb D family, and three variants with electrophoretic mobilities identical or similar to that of Hb C. Six variants with electrophoretic mobilities identical or similar to that of Hb S could be differentiated and identified by retention time and proportion of total hemoglobin. HPLC detected two variants (Hb Ty Gard and Hb Twin Peaks) missed on electrophoresis.</AbstractText>The retention time on HPLC is reliable, reproducible, and in many cases superior to conventional hemoglobin electrophoresis for the detection and identification of hemoglobin variants. Confirmatory testing by electrophoresis can be eliminated in the majority of cases by use of retention time, proportion of total hemoglobin, and peak characteristics of HPLC.</AbstractText>
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2,339,055 |
Diabetes mellitus in adults: association of HLA DRB1 and DQB1 diabetes risk alleles with GADab presence and C-peptide secretion.
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In our study, we investigated the relationship of HLA class II alleles to antibody production against glutamic acid decarboxylase (GADab) and to C-peptide secretion (CP) in diabetic patients. A group of 334 patients (190 women) diagnosed after 35 years of age and 99 control subjects were studied. Patients were divided into four groups according to concentrations of CP and GADab, respectively (CP high/low, GADab positive/negative). HLA DQB1 and DRB1 alleles were genotyped by SSP-PCR. The significance of DQB1 and DRB1 risk alleles was evaluated by examination of their odds ratios computed by testing 2x2 tables considering Bonferonis' corrected P<0.05 as significant. We found strong association between the HLA DRB1*03 risk allele and presence of GADab, and close relationship of the HLA DRB1*04 and HLA DQB1*0302 risk alleles with decreased CP level. Taken together we conclude that the DRB1*04 and DQB1*0302 alleles are associated with progressive decrease of CP level, while DRB1*03 is a significant genetic marker of autoantibody (GADab) development.
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2,339,056 |
Quality assessment in cytogenetic and molecular genetic testing: the experience of the Italian Project on Standardisation and Quality Assurance.
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The first Italian national trial of external quality assessment in genetic testing was organised within the framework of the "Italian National Project for Standardisation and Quality Assurance of Genetic Tests". Sixty-eight Public Health Service laboratories volunteered for the trial, which involved molecular genetic tests (cystic fibrosis, beta-thalassaemia, familial adenomatous polyposis coli and fragile-X syndrome) and cytogenetic tests (prenatal and postnatal, the latter included cancer cytogenetics). The response rate was high (88.2%). The level of analytical accuracy was good, i.e., the percentage of laboratories that correctly genotyped all samples was 89.3% for cystic fibrosis, 90.9% for beta-thalassaemia, 100% for familial adenomatous polyposis coli (despite two laboratories did not complete the analysis because the amount of DNA was considered insufficient), and 90.5% for fragile-X syndrome. Written reports differed widely and were judged "inadequate" in over 50% of cases. Most laboratories from the present study already have experience in previous European external quality assessments for at least one genetic test; this can explain the higher analytical accuracy in the Italian external quality assessment with respect to quality control programmes in other countries. Collaborative networks are strongly suggested to improve the quality of the reports.
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2,339,057 |
Using the common sense model to understand perceived cancer risk in individuals testing for BRCA1/2 mutations.
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The common sense model posits that individuals' understanding of illness is based upon somatic symptoms and life experiences and thus may differ significantly from the biomedical view of illness. The current study used the common sense model to understand cancer risk perceptions in 99 individuals testing for BRCA1/2 mutations. Specifically, we examined change from post-counseling to post-result in (1) absolute risk (risk of developing cancer in one's lifetime) and (2) comparative risk (risk relative to the general population). Results indicated that absolute risk showed a trend such that those with a personal history of cancer receiving uninformative negative results reported decreased absolute risk. Further, individuals receiving uninformative negative results reported decreased comparative risk. Those with no personal cancer history receiving informative negative results did not decrease in risk over time nor did their risk differ from those with a personal cancer history, evidencing unrealistic pessimism regarding their risk of cancer. The reasons provided for individuals' risk perceptions could be classified in terms of attributes of the common sense model and included the: (1) causes of cancer (e.g. family history, mutation status); (2) control or cure of cancer through health behaviors and/or surgery; and (3) perceived timeline for developing cancer (e.g. time left in life to develop cancer). We conclude that key to developing interventions to improve understanding of cancer risk and promoting effective cancer control mechanisms is an understanding of the specific reasons underlying individuals' perceptions of cancer risk.
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2,339,058 |
Knowledge of risk management strategies, and information and risk management preferences of women at increased risk for ovarian cancer.
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Little research is available on the level of knowledge about ovarian cancer risk management options in women at increased risk for this disease. The study objectives were to evaluate this together with the information and ovarian cancer risk management preferences of high-risk women. One hundred and twenty-nine women were assessed after their attendance at one of six familial cancer clinics in relation to knowledge of surveillance and/or preventative strategies for reduction of ovarian cancer risk, preferences for particular strategies, and information preferences. Screening was selected by 57 (44%) women as the preferred risk management option. One hundred and five women (82%) indicated a wish for as much information as possible about ovarian cancer, including both good and bad outcomes and 114 (89%) reported a preference for sharing treatment decisions with their health professional. Participants' knowledge about ovarian cancer risk management options was significantly associated with educational levels (Z = -3.2, p=0.001) and whether or not ovarian cancer was included in the family history (Z = -2.3, p = 0.018). Findings from this present study indicate that women at increased risk of ovarian cancer who attend familial cancer clinics want as much information as possible about this disease and they want to be involved in the decision-making process. Women who reported a lower level of education (no post-school qualifications) may be most likely to benefit from additional educational strategies designed to supplement genetic counseling to improve their knowledge levels.
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2,339,059 |
Germline mosaicism complicates molecular diagnosis of Lesch-Nyhan syndrome.
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A healthy female with a brother suffering from Lesch-Nyhan syndrome was assigned a carrier status on the basis of haplotype analysis employing flanking and intragenic polymorphic markers of the HPRT gene. Her mother has been confirmed as a definite carrier by cell growth selection studies in cultured fibroblasts. In our proposita's first pregnancy, a male fetus was identified carrying the risk allele. Afterwards, the underlying novel mutation A161E (GCA-->GAA at position c482) could be identified in the affected brother and in the heterozygous mother but not in the DNA of the pregnant sister and fetus. The fetus was also confirmed to be normal by uptake of 14C-hypoxanthine in cultured amniotic cells. To test the discrepancy, the investigation was extended by recruiting additional family members. The data obtained showed that the mother had passed her risk haplotype to the affected son as well as to her mutation-carrying and non-mutation-carrying daughters. This provides the first evidence of concomitant somatic and germline mosaicism in Lesch-Nyhan syndrome. The study has a bearing on genetic counselling and cautions against the reliability of only using indirect genetic diagnosis even with intragenic markers.
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2,339,060 |
Genomic analysis of prostate carcinoma specimens obtained via ultrasound-guided needle biopsy may be of use in preoperative decision-making.
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The widespread use of prostate-specific antigen (PSA) testing to screen for prostate carcinoma has led to significant overdiagnosis, due to the frequent detection of indolent malignancies on PSA screening. The detection of abnormal PSA levels typically is followed by ultrasound-guided needle biopsy. Therefore, in an effort to identify genetic markers that augment the information provided by standard histopathologic classification, the authors tested the feasibility of using these minute biopsy samples for genomic profiling via chromosome banding analysis and comparative genomic hybridization (CGH).</AbstractText>Ultrasound-guided needle biopsy specimens obtained preoperatively from 35 patients with prostate carcinoma were analyzed via chromosome banding analysis (after short-term culturing) and CGH. The findings of these analyses then were analyzed for potential correlations with clinicopathologic parameters.</AbstractText>Chromosome banding analysis and CGH were possible in 34 and 33 of the 35 study specimens, respectively. Combined analysis revealed aberrations in 69% of all samples investigated. Copy number losses occurred most commonly at 8p (58% of all abnormal specimens), 16q (42%), and 13q (37%), whereas the only gains detected in more than 1 specimen were those that occurred at 8q (37%). Genomic imbalances and losses at 16q were significantly associated with more poorly differentiated subtypes of prostate carcinoma (P = 0.048 and P = 0.019, respectively), whereas gains at 8q and losses at 16q were significantly correlated with clinically advanced disease (P = 0.048 for the finding of a gain at 8q together with a loss at 16q; P = 0.01 for the finding of either aberration alone).</AbstractText>The authors conclude that genomic analysis of suspected prostate carcinoma specimens obtained via ultrasound-guided needle biopsy is feasible. Thus, it may be possible to use genetic markers to obtain diagnostic and/or prognostic information that is useful in the making of preoperative decisions regarding prostate carcinoma management.</AbstractText>
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2,339,061 |
Examining the terminal investment hypothesis in humans and chimpanzees: associations among maternal age, parity, and birth weight.
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The terminal investment hypothesis (Williams [1966] Adaptation and Natural Selection; Princeton, NJ: Princeton University Press) holds that reproductive effort should increase over time in iteroparous species in which reproductive value declines with age. Attempts to model this hypothesis and test it in various species have produced mixed results. Clutton-Brock ([ 1984] Am. Nat. 123:212-229) argued that simply testing for changes in propagule size with age fails to recognize that the costs of producing offspring of a given size may increase over the lifespan, hence absence of a positive correlation does not defeat the hypothesis. However, this interpretation is weakened by evidence of sequential increases in propagule size independent of age, as such changes reveal a capacity to increase absolute investment over time. Humans and chimpanzees meet the preconditions of the terminal investment hypothesis. Surveying the obstetrics literature, we show that the majority of published studies indicate that parity has a positive effect on birth weight, but age has no effect. Analyzing 436 captive chimpanzee births, we document a positive influence of parity and a negative influence of age. We therefore conclude that, though it is yet to be replaced by a more compelling alternative, the terminal investment hypothesis is not supported in these two species, as absence of a positive effect of age on birth weight cannot be interpreted in a manner congruent with the hypothesis.
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2,339,062 |
Evidence and characteristics of putative human alpha recombination hotspots.
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Understanding recombination rate variation is very important for studying genome diversity and evolution, and for investigation of phenotypic association and genetic diseases. Recombination hotspots have been observed in many species and are well studied in yeast. Recent study demonstrated that recombination hotspots are also a ubiquitous feature of the human genome. But the nature of human hotspots remains largely unknown. We have developed and validated a novel computational method for testing the existence of hotspots as well as for localizing them with either unphased or phased genotyping data. To study the characteristics of hotspots within or close to genes, we scanned for unusually high levels of recombination using the European population samples in the SeattleSNPs database, and found evidence for the existence of human alpha hotspots similar to those of yeast. This type of hotspots, found at promoter regions, accounts for about half of the total detected and appears to depend on some specific transcription factor binding sites (such as CGCCCCCGC). These characteristics can explain the observed weak correlation between hotspots and GC-content, and their variation may contribute to the diversity of hotspot distribution among different individuals and species. These long-sought putative human alpha recombination hotspots should deserve further experimental investigations.
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2,339,063 |
Safety concerns related to hematopoietic stem cell gene transfer using retroviral vectors.
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Endogenous retroviruses have developed efficient methods during their life cycle for stable integration into the host genome. Because of this ability, retroviral vectors were designed with the goal of gene transfer into hematopoietic stem cells (HSCs). The ability to genetically modify HSCs provides a vehicle for durable expression of potentially therapeutic transgenes in all lineages of mature blood cells for the lifetime of the patient. Combined with bone marrow transplant, retroviral gene transfer has many potential applications for a wide range of blood diseases. Advances in the development of oncoretroviral vectors based on murine leukemia viruses (MLV) and more recent development of human immunodeficiency virus (HIV)-based vectors have greatly increased the gene transfer efficiency. Optimization of methods for gene transfer using MLV-based vectors has substantially improved marking levels in mice, with lower levels in large animals and in human clinical trials. With advances in gene transfer technology has also come renewed concern about insertional mutagenesis and activation of oncogenes. Advanced techniques for integration site analysis combined with sequence comparison using mouse and human genome databases has now made it possible to begin to understand the spectrum of possible integration sites for both MLV- and HIV-based vectors. Furthermore, other studies have shown positive and negative dosage-dependent effects of transgene expression in mouse and human cells. Therefore, vector design and safety testing are at the forefront of the field of gene therapy and this review discusses recent developments.
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2,339,064 |
Supporting patients through genetic screening for cancer risk.
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A format for obtaining a genetic family health history is presented, along with a discussion of the importance of psychosocial support surrounding the genetic screening process and the responsibility for the maintenance of the privacy of medical records of patients who elect to undergo genetic screening, are presented.
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2,339,065 |
Field and storage testing Bt potatoes for resistance to potato tuberworm (Lepidoptera: Gelichiidae).
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Potato tuberworm, Phthorimaea operculella (Zeller), is the most serious insect pest of potatoes worldwide. The introduction of the Bacillus thuringiensis (Bt) toxin gene through genetic engineering offers host plant resistance for the management of potato tuberworm. We report on the field and storage studies to evaluate Bt-cry5 potato lines for resistance to potato tuberworm in Egypt under natural infestations and their agronomic performance in both Egypt and Michigan. From 1997 to 2001, field experiments were conducted at the International Potato Center (CIP) Research Station, Kafr El-Zyat, Egypt, and/or Agricultural Genetic Engineering Institute (AGERI), Giza, Egypt, to evaluate resistance to tuberworm. A total of 27 Bt-transgenic potato lines from six different Bt constructs were evaluated over a 5-yr period. After harvest and evaluation of the agronomic trials, storage evaluation of potato tuberworm damage was done at the CIP Research Station. The 1997 field trial was the first field test of genetically engineered crops in Egypt. Field tests to assess potato tuberworm resistance in Egypt were able to differentiate between the Bt-transgenic lines and the nontransgenic lines/cultivars in 1999, 2000, and 2001. The Bt-cry5-Spunta lines (Spunta-G2, Spunta-G3, and Spunta-6a3) were the most resistant lines in field with 99-100% of tubers free of damage. In the 2001 storage study, these lines were also over 90% free of tuberworm damage after 3 mo. NYL235-4.13, which combines glandular trichomes with the Bt-cry5/gus fusion construct, also had a high percentage of clean tubers in the field studies. In agronomic field trials in Michigan from 1997 to 2001, the Bt-transgenic lines in most instances performed similar to the nontransgenic line in the agronomic trials; however, in Egypt (1998-1999), the yields were less than one-half of those in Michigan. Expression of the Bt-cry5 gene in the potato tuber and foliage will provide the seed producer and grower a tool in which to reduce potato tuberworm damage to the tuber crop in the field and storage.
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2,339,066 |
Single nucleotide polymorphism analysis in the human phosphatase PTPrj gene using matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry.
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Data derived from analysis of single nucleotide polymorphisms (SNPs) are being applied in many diverse fields, from medical studies of disease mechanisms and individual drug response, to population genetics for tracking migration and mixing of ancestral groups and also in forensic science for the identification of human remains and identification of individuals from bodily samples. All these applications have in common the need to generate data for multiple loci from large numbers of samples. Matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOFMS) is a promising platform for the generation of such data and we present a simple, flexible and robust technique for SNP determination. We demonstrate these features by typing two SNPs (Q276P and R326Q) in the human phosphatase gene PTPrj, which has been implicated in the aetiology of colon, lung, breast and thyroid cancers. A nucleotide depletion primer extension assay using no commercial kits or dideoxyNTPs was used to genotype a panel of DNAs derived from thyroid cancer patients and normal volunteers. The results obtained were in perfect agreement with those generated via restriction fragment length polymorphism analysis. No significant association was noted between possession of either allelic variant and a disease state, but the technique was validated as simple, flexible and appropriate for application in this context. Furthermore, it was highly cost-effective and required minimal optimisation, rendering it ideal for this type of pilot study.
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2,339,067 |
Medullary cystic kidney disease type 1 in a large Native-American kindred.
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Autosomal dominant medullary cystic kidney disease type 1 (MCKD1; Mendelian Inheritance in Man 174000) is a hereditary tubulointerstitial renal disease. For MCKD1, a locus on chromosome 1q21 is published. Although there are characteristic biopsy and imaging findings for MCKD, clinical diagnosis of this disorder is still very difficult because unique phenotypic features are not always present in individual cases.</AbstractText>In a large Native-American kindred with apparent autosomal dominant nephropathy, clinical findings in more than 50 individuals were collected and evaluated. Haplotype analysis for 34 individuals was performed.</AbstractText>We report the difficulties establishing the diagnosis of MCKD in a large Native-American kindred solely by means of clinical criteria. This kindred shows a wider range of age of disease onset than previously reported. Gout and hypertension were common, but no patient reported symptoms of salt wasting. By means of haplotype analysis linkage was shown to the MCKD1 locus (logarithm of the odds score, 3.34).</AbstractText>Establishing a diagnosis of MCKD solely on clinical findings is difficult because signs and symptoms may be subtle, renal cysts may be absent in more than 50% of affected individuals, and renal histological abnormalities are nonspecific. In patients presenting with renal insufficiency from apparent interstitial disease, a thorough family history and genetic linkage studies are required to establish a diagnosis of MCKD. We suspect MCKD is underdiagnosed and the true incidence of MCKD1 in the general population may be underestimated. No further living-related transplantation should be performed until genetic testing can exclude potentially affected donors.</AbstractText>
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2,339,068 |
Recent mammalian gene duplications: robust search for functionally divergent gene pairs.
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Comparison of 317 gene pairs in human and mouse that were duplicated after the most recent common ancestor of the two species was used to search for candidates that may have undergone functional differentiation. Even when corrected for multiple tests, Tajima's relative rate test showed significant rate differences in 36% of cases for which the test was applicable. However, a significant result in this case was increasingly likely as the sequence length increased; thus, a statistically significant result of a relative rate test may not be biologically meaningful. We used regression methods to provide more robust methods of testing for functionally differentiated gene pairs, which take into account the variation in the entire data set by examination of residuals from regression-identified gene pairs with unusually high nonsynonymous divergence from a reference sequence and from each other. This approach identified six duplicate gene pairs that appeared to be candidates for functional differentiation as a result of positive Darwinian selection.
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2,339,069 |
Cutting edge: heterozygote advantage in autoimmune disease: hierarchy of protection/susceptibility conferred by HLA and killer Ig-like receptor combinations in psoriatic arthritis.
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Functionally relevant combinations of HLA and killer Ig-like receptor (KIR) genotypes influence resistance to several diseases in humans. Analysis of genetic data from such studies is challenging because it involves multiple linked and unlinked loci that exert their influence in an epistatic manner. We previously reported that subjects with certain activating receptors were susceptible to developing psoriatic arthritis (PsA), an effect that was strongest when HLA ligands for corresponding homologous inhibitory receptors were missing. In this study, we present a novel model in which susceptibility to PsA is determined by the overall balance of activating and inhibitory composite KIR-HLA genotypes. This model fits our knowledge of clonal NK cell expression of KIR and regulation of NK cell activity better than does the previous model, as reflected in a robust trend for increasing susceptibility to PsA with more activating genotypes. These data emphasize the remarkable influence of KIR/HLA combinations on this disease.
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2,339,070 |
Does this patient have a family history of cancer? An evidence-based analysis of the accuracy of family cancer history.
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A family history of certain cancers is associated with an increased risk of developing cancer. Both cancer screening and genetic services referral decisions are often based on self-reported pedigree information.</AbstractText>To determine the accuracy of self-reported family cancer history information.</AbstractText>English-language articles were retrieved by searching MEDLINE (1966-June 2004) using Medical Subject Headings family, genetic predisposition to disease, medical history taking, neoplasm, and reproducibility of results. Additional articles were identified through bibliography searches.</AbstractText>Original studies in which investigators validated self-reported family history by reviewing the identified relatives' medical records, death certificate, or cancer registry information were included, as well as studies that evaluated breast, colon, ovarian, endometrial, and prostate cancers.</AbstractText>Two of the 3 investigators independently reviewed and abstracted data for estimating the likelihood ratios (LRs) of self-reported family cancer history information. Only data from studies that evaluated both positive and negative family cancer histories were included within the analyses. A total of 14 studies met the search criteria and were included in the review.</AbstractText>For patients without a personal history of cancer, the positive and negative LRs of a family history of the following cancers in a first-degree relative were 23.0 (95% confidence interval [CI], 6.4-81.0) and 0.25 (95% CI, 0.10-0.63) for colon cancer; 8.9 (95% CI, 5.4-15.0) and 0.20 (95% CI, 0.08-0.49) for breast cancer; 14.0 (95% CI, 2.2-83.4) and 0.68 (95% CI, 0.31-1.52) for endometrial cancer; 34.0 (95% CI, 5.7-202.0) and 0.51 (95% CI, 0.13-2.10) for ovarian cancer; and 12.3 (95% CI, 6.5-24.0) and 0.32 (95% CI, 0.18-0.55) for prostate cancer, respectively. Positive predictive values tended to be better in articles concerning first-degree relatives compared with second-degree relatives.</AbstractText>Patient-reported family cancer histories for first-degree relatives are accurate and valuable for breast and colon cancer risk assessments. Negative family history reports for ovarian and endometrial cancers are less useful, although the prevalence of these malignancies within families is low.</AbstractText>
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2,339,071 |
The "duty to warn" a patient's family members about hereditary disease risks.
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Genetic tests for adult-onset disorders, including common forms of cancer, are now commercially available, and tests for genetic polymorphisms that predict drug effects or toxicity after treatment are under development. For each of these circumstances, testing of 1 individual may imply an increased risk to his/her relative. The obligation, if any, to warn family members of the identification of a genetic mutation has generated concerns regarding the conflict between the physician's ethical obligations to respect the privacy of genetic information vs the potential liabilities resulting from the physician's failure to notify at-risk relatives. A duty to warn relatives about risks due to some infectious agents has been assumed by state and local health agencies, and the duty to breach confidentiality to warn of imminent harm has been the subject of case law. In general, the special nature of genetic tests has been viewed as a barrier to physicians' breaching the confidentiality of personal genetic information. However, the failure to warn family members about hereditary disease risks has already resulted in 3 lawsuits against physicians in the United States. While the findings of case law and the state and federal statutes that bear on the issue of "duty to warn" of inherited health risk are still being defined, we believe that health care professionals have a responsibility to encourage but not to coerce the sharing of genetic information in families, while respecting the boundaries imposed by the law and by the ethical practice of medicine.
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2,339,072 |
Activity of rifampin against Mycobacterium tuberculosis in a reference center.
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Rifampin is a bactericidal antibiotic that acts both on extra- and intracellular bacilli. It inhibits RNA synthesis by binding to the beta-subunit in the RNA polymerase. A study was conducted on rifampin resistance from 1993 to 2002 with 1,794 Mycobacterium tuberculosis strains submitted to Mycobacteria Reference Center, Córdoba, Spain. A total of 1,460 of these strains came from pulmonary specimens and 235 from extrapulmonary specimens. All strains were identified by conventional morphological, bacteriological, biochemical, genetic, and chromatographic methods. For 99 strains, the source was not indicated. Initially, the BACTEC 460 TB system was used for antibiotic sensitivity testing. Since 1996, the ESP II system was also used. The strains ATCC27294 (sensitive to streptomycin, rifampin, ethambutol, and isoniazid) and ATCC38838 (resistant to rifampin) were used as controls. The resistance degree detected was 10.03%, of which 1.2% and 8.7% corresponded to primary and secondary resistances, respectively. A total of 137 strains showed multiresistance. The surveillance of resistance and of the potential factors that may lead to an increase in resistance is thus warranted.
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2,339,073 |
Creating clones, kids & chimera: liberal democratic compromise at the crossroads.
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The objective of this article is to find middle ground between the supporters and opponents of biotechnology by perpetuating the existing legal compromise pertaining to the complete range of health and welfare doctrines relevant to the biotechnological industry. The author aspires neither to add to nor detract from this liberal democratic consensus, but to preserve its constitutive balance between positivism and natural law and over-regulation and under-regulation in the hopes of stabilizing new political fault lines developing around the few biotechnological innovations already grabbing headlines. The most feasible solution is to extend the existing liberal democratic compromise with respect to equal protection, reproductive rights, the First Amendment, human subject experimentation, patent law, and parental rights. This includes banning or monopolizing certain biotechnologies and extending substantive special respect to the ex vivo living human embryo. Biotechnology must not be left to regulate itself.
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2,339,074 |
A comparative study of culture-independent, library-independent genotypic methods of fecal source tracking.
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Culture-independent fecal source tracking methods have many potential advantages over library-dependent, isolate-culture methods, but they have been subjected to limited testing. The purpose of this study was to compare culture-independent, library-independent methods of fecal source tracking. Five laboratories analysed identical sets of aqueous samples that contained one or more of the following sources: sewage, human feces, dog feces, cattle feces and gull feces. Two investigators used methods based on PCR amplification of Bacteroidetes marker genes and both successfully discriminated between samples that did or did not contain human fecal material. One of these investigators was also able to identify the remaining sources, except for gull, with a low rate of false positives. A method based on E. coli toxin genes successfully identified samples containing sewage and cattle feces, but missed some samples with human feces because of low marker prevalence in individual human fecal samples. Researchers who used community terminal restriction fragment length polymorphism (T-RFLP) were limited by the amount of DNA recovered from samples, but they correctly identified human and cattle fecal contamination when sufficient DNA was obtained. Culture independent methods show considerable promise; further research is needed to develop markers for additional fecal sources and to understand the correlation of these source-tracking indicators to measures of human and environmental health.
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2,339,075 |
An X-linked three allele model of hand preference and hand posture for writing.
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This paper describes a genetic model of hand preferences for writing and for handwriting posture (HWP). The challenge of devising an X-linked model for these aspects of human handedness was posed by the results of a large family handedness study (McKeever, 2000) that showed evidence of such linkage. Because X-linkage for handedness has been widely regarded as untenable, the prospects for developing such a model were not initially encouraging, but ultimately a viable model did suggest itself. Family studies of handedness and leading theories of handedness are briefly described, as is some of the research on HWP motivated by the theory of Levy and Nagylaki (1972). It is argued that there is evidence that HWP reflects a biological dictate and not just individual "choices" or "adaptations" to writing in a left-to-right direction with the left hand. The model proposes that inverted handwriting posture is not necessarily highly related to speech and language lateralities of sinistrals, but that it reveals an interhemispheric mediation of writing. It is hypothesised that it reflects a specialisation of the left angular gyrus (with some possible extension into the supramarginal gyrus) for the storage of movement and timing sequences of cursive writing, and right hemisphere motor programming of the motor output of writing. It is also argued that no family handedness study conducted to date is adequate for testing the predictions of extant handedness theories, and the often wide variations between the results of family handedness studies are noted. It is suggested that fMRI studies could definitively test the HWP hypotheses of the model and that the hypothesis of X-linkage could be tested definitively should studies of the human genome identify a gene for handedness.
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2,339,076 |
Inherited predisposition to early onset lung cancer according to histological type.
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The role of hereditary factors in lung cancer is less well understood than in many other human neoplastic diseases. We used a nation-wide family dataset to search for evidence for a genetic predisposition in lung cancer. The Swedish Family-Cancer Database includes all Swedes born in 1932 and later (0- to 68-year-old offspring) with their parents, totaling over 10.2 million individuals. Cancer cases were retrieved from the Swedish Cancer Registry up to year 2000. Standardized incidence ratios (SIR) and 95% confidence limits (CI) were calculated for age-specific familial risks in offspring by parental or sibling proband, separately. A Kappa test was used to examine the association between familial risk and histology. Compared to the rate of lung cancers among persons without family history, a high risk by parental family history in adenocarcinoma (2.03) and large cell carcinoma (2.14) was found, and only a slightly lower risk was found among patients with squamous cell carcinoma (1.63) and small cell carcinoma (1.55). Among siblings, an increased risk was shown for concordant adenocarcinoma and small cell carcinoma at all ages and for all histological types when cancer was diagnosed before age 50. At young age, risks between siblings were higher than those between offspring and parents. The present data suggest that a large proportion of lung cancers before age 50 years appears to be heritable and probably due to a high-penetrant recessive gene or genes that predispose to tobacco carcinogens; however, this hypothesis needs to be tested in segregation analysis with a large number of pedigrees.
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2,339,077 |
Prevention of breast cancer in women who carry BRCA1 or BRCA2 mutations: a critical review of the literature.
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The purpose of our study was to review the evidence for the efficacy of surveillance for early detection, bilateral prophylactic mastectomy, prophylactic oophorectomy and chemoprevention in preventing breast cancer and improving survival of BRCA1 or BRCA2 carriers. A critical review of journal articles published between 1998 and 2004 identified by searches of MEDLINE, PubMed and references of retrieved articles was undertaken. None of the current evidence is based on randomized studies. The efficacy of surveillance for early detection of breast cancer among BRCA1 or BRCA2 carriers is not yet established. Screening with clinical breast examination and mammography showed lower sensitivity in BRCA1 or BRCA2 carriers than in the general population. Screening with MRI might offer higher sensitivity rates than mammography. Prophylactic mastectomy was shown to significantly reduce the risk of breast cancer by 89.5-100%. However, of all strategies reviewed, mastectomy was the least acceptable to women at high risk. Tamoxifen use was associated with breast cancer prevention among BRCA2 carriers (RR=0.38, 95%CI: 0.06-1.56). In BRCA1 or BRCA2 carriers with breast cancer, tamoxifen use was associated with the prevention of secondary breast cancer (OR= 0.50, 95% CI: 0.28-0.89). Prophylactic oophorectomy was associated with hazard ratios for breast cancer of 0.47 (95%CI:0.29-0.77) and 0.32 (95%CI: 0.08-1.20), in retrospective and short follow-up prospective cohort studies, respectively. There is a pressing need for more studies in order to determine which of the 4 strategies alone, or in combination, is the most effective for the prevention of breast cancer and for the improvement of survival of BRCA mutation carriers.
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2,339,078 |
Genetic counseling program in familial breast cancer: analysis of its effectiveness, cost and cost-effectiveness ratio.
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Women with a family history of breast cancer are at increased risk for developing this neoplasm. Starting surveillance more frequently at a younger age than the general population and the possibility of undergoing genetic testing are options for their medical management. We analyzed the benefits and costs of our clinical program in familial breast cancer (FBC) and carried out a cost-effectiveness analysis of such procedure. The benefits and costs of performing genetic counseling and a screening program in FBC based on 143 high-risk families registered in our database between June 1995 and December 2001 were analyzed. A decision tree was constructed to estimate the survival benefit and cost-effectiveness of the clinical genetic counseling program compared with the strategy of not performing any screening protocol. We estimated that the prevalence of a BRCA mutation in an unaffected relative of our high-risk cohort was 10% and that 53% of the mutations are found in the BRCA1 gene. We assigned a 58.5% lifetime risk of breast cancer for a 30-year-old mutation carrier according to the SEER data. The effectiveness of the screening was obtained from our experience and data for estimating survival were derived from other studies with longer follow-up. We used our local payment data to calculate the costs of the program. A mutation in the BRCA1 or BRCA2 genes was identified in 20% of the probands. Seventy primary breast cancer cases were recorded since the onset of the program. Thirty percent of the tumors were diagnosed through the screening program and 71% of them were lymph node-negative compared to 49% of the tumors diagnosed outside the program (p=0.1). The cost-effectiveness ratio of our FBC genetic counseling and screening program was 4,294 euros per life-year gained. The model was sensitive to the prevalence of mutation carriers, the lifetime risk of breast cancer and the effectiveness of the screening. In our setting and according to our model, this analysis suggests that a program of genetic testing and screening for breast cancer in a high-risk population may be cost-effective. These results need to be confirmed as more effective interventions for cancer prevention and screening are being implemented.
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2,339,079 |
The BOADICEA model of genetic susceptibility to breast and ovarian cancer.
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Several genes conferring susceptibility to breast and ovarian cancer, notably BRCA1 and BRCA2, have been identified. The majority of the familial aggregation of breast cancer is, however, not explained by these genes. We have previously derived, using segregation analysis, a susceptibility model (BOADICEA, Breast and Ovarian Analysis of Disease Incidence and Carrier Estimation Algorithm) in which susceptibility to these genes is explained by mutations in BRCA1 and BRCA2 together with a polygenic component reflecting the joint multiplicative effect of multiple genes of small effect on breast cancer risk. Here, we consider the predictions made by this model. The overall familial risks of breast cancer predicted by this model are close to those observed in epidemiological studies. The predicted prevalences of BRCA1 and BRCA2 mutations among unselected cases of breast and ovarian cancer are also consistent with observations from population-based studies. These predictions are closer to the observed values than those obtained using the Claus model and BRCAPRO. The predicted mutation probabilities and cancer risks in individuals with a family history (FH) can differ markedly from those predicted by other models. We conclude that this model provides a rational basis for risk assessment in individuals with a FH of breast or ovarian cancer.
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2,339,080 |
Huntington disease: a case study of early onset presenting as depression.
|
Huntington disease is a dominantly inherited, neurodegenerative disease characterized by choreiform movement disturbances and dementia, usually with adult onset. The rare juvenile-onset Huntington disease differs from the adult phenotype. A case presenting twice, at age 10 with all the signs of a major depression and age 14 with mutism and rigidity, is reported. Meanwhile, the father developed the adult variant of Huntington disease. The boy's diagnosis was confirmed by molecular genetic analysis and magnetic resonance imaging. It is important to be aware of hereditary conditions such as Huntington disease and to provide family counseling before genetic testing and after the diagnosis is confirmed.
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2,339,081 |
ACE1 polymorphism and progression of SARS.
|
We have hypothesized that genetic predisposition influences the progression of SARS. Angiotensin converting enzyme (ACE1) insertion/deletion (I/D) polymorphism was previously reported to show association with the adult respiratory distress syndrome, which is also thought to play a key role in damaging the lung tissues in SARS cases. This time, the polymorphism was genotyped in 44 Vietnamese SARS cases, with 103 healthy controls who had had a contact with the SARS patients and 50 controls without any contact history. SARS cases were divided into either non-hypoxemic or hypoxemic groups. Despite the small sample size, the frequency of the D allele was significantly higher in the hypoxemic group than in the non-hypoxemic group (p=0.013), whereas there was no significant difference between the SARS cases and controls, irrespective of a contact history. ACE1 might be one of the candidate genes that influence the progression of pneumonia in SARS.
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2,339,082 |
Association of a CAG/CAA repeat sequence in the TBP gene with type I diabetes.
|
Type I diabetes is a complex disease in which multiple susceptibility loci have been implicated by whole genome scans. IDDM8, a susceptibility locus, is located on chromosome 6q27, however the specific susceptibility gene has yet to be identified. We have examined five potential candidate genes using 36 genetic markers, spanning 360kb located near the chromosome 6q27 terminus in 478 families for diabetes association. No associations with type I diabetes susceptibility were detected with the strength previously observed for IDDM1 or IDDM2. However, a novel CAG/CAA polymorphism was detected in exon 3 of the TATA box-binding protein gene, which shows preliminary evidence of association with diabetes susceptibility (p<0.05).
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2,339,083 |
Evidence of ABL-kinase domain mutations in highly purified primitive stem cell populations of patients with chronic myelogenous leukemia.
|
To study the hierarchical levels of stem cell targets for ABL-kinase domain mutations in CML, highly purified CD34+CD38- and CD34+CD38+ cell populations and their LTC-IC-derived progeny were analyzed in four patients at diagnosis (n=1) or in advanced phases (n=3) of their disease. In the single patient with early phase CML who later developed an Imatinib Mesylate-resistance and a Y253H mutation, no mutation was detectable in purified cell fractions analyzed at diagnosis nor in their LTC-IC-derived progeny. In contrast, in three patients in advanced phase CML, ABL-kinase mutations demonstrated in peripheral blood cells by sequencing (Q252E and M351T) were detectable in the FACS-sorted cells and became amplified in the LTC-IC-derived progeny of the primitive cells. These findings demonstrate that in late CP or advanced CML, ABL-kinase mutations occur as an intraclonal event in the primitive Ph1+ stem cell compartments with progression of this clone towards IM-resistant blast phase.
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2,339,084 |
Myoclonus: current concepts and recent advances.
|
Myoclonus presents as a sudden brief jerk caused by involuntary muscle activity. An organisational framework is crucial for determining the medical significance of the myoclonus as well as for its treatment. Clinical presentations of myoclonus are divided into physiological, essential, epileptic, and symptomatic. Most causes of myoclonus are symptomatic and include posthypoxia, toxic-metabolic disorders, reactions to drugs, storage disease, and neurodegenerative disorders. The assessment of myoclonus includes an initial screening for those causes that are common or easily corrected. If needed, further testing may include clinical neurophysiological techniques, enzyme activities, tissue biopsy, and genetic testing. The motor cortex is the most commonly shown myoclonus source, but origins from subcortical areas, brainstem, spinal, and peripheral nervous system also occur. If treatment of the underlying disorder is not possible, treatment of symptoms is worthwhile, although limited by side-effects and a lack of controlled evidence.
|
2,339,085 |
Ethical implications in genetic counseling and family studies of the epilepsies.
|
Most of the inherited epilepsies do not follow a Mendelian inheritance pattern but rather are complex disorders. This leads us to reconsider the traditional ethical framework applying to genetics, which is still based largely on the understanding of Mendelian inheritance, to ethically use the genetic tests likely to be forthcoming for the prevention and surveillance of epilepsies. This article is a review of the ethical issues raised by family studies of the epilepsies, in both a clinical and a research context. These issues include the use of genetic tests, the scope of genetic counseling, the upholding of the risk-benefit ratio in pharmacogenetics, as well as those related to the availability of treatments, health professionals' changing responsibilities, and the communication within families. A reasonable approach calls for a case-by-case determination of whether the benefit and harm of genetic testing outweigh benefit and harm of protecting autonomy and nonmaleficence.
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2,339,086 |
CFTR mutations and polymorphisms in male infertility.
|
Apart from cystic fibrosis, mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene are also involved in congenital bilateral absence of the vas deferens (CBAVD). A mutation is identified in about 80% of the CFTR genes derived from CBAVD patients; the genetic defect in the remainder is yet unknown. In contrast to CF patients, when CFTR is involved, at least one of the mutant CFTR genes of CBAVD patients harbors a mild mutation. A polyvariant mutant CFTR gene is the most frequent CBAVD causing mutant CFTR gene. Here, combinations of particular alleles at several polymorphic loci yield insufficient functional CFTR. The fact that most CBAVD patients, that carry mutations on both CFTR genes, have no lung disease is most probably explained by tissue specific alternative splicing, which is increased in vas deferens compared to bronchial tissue. It has also been reported that CBAVD may be involved in other forms of infertility than CBAVD, however this has not always been confirmed in other studies. Because of techniques such as intracytoplasmic sperm injection, CBAVD patients are now able to father children, however such couples have an increased risk of having a child with cystic fibrosis, and therefore genetic testing and counselling should be provided.
|
2,339,087 |
Targeting the ERK pathway: novel therapeutics for thyroid cancer.
|
Over the past two decades significant progress has been made in elucidating the pathogenesis of thyroid cancer. The ongoing identification of mutations in cellular signaling pathways has revolutionized the field of thyroid cancer biology and has led to the development of novel new therapeutic agents. One of the signaling cascades implicated in the oncogenic process is the ERK pathway that normally functions to transmit mitogenic signals from the cell membrane to the nucleus. Genetic alterations of key components of this cascade, namely RET, Ras and Raf, are thought to result in constitutive activation of the pathway and subsequent thyroid tumorigenesis. Targeting of these components with pharmaceutical agents holds the potential of providing newer and more effective treatment modalities for thyroid cancer. Several such drugs are currently being developed to inhibit RET, Ras, Raf, as well as other factors impacted by the ERK pathway. These include a vast array of agents such as antisense compounds, small molecule inhibitors as well as inhibitors of farnesyl transferase, heat shock proteins, matrix metalloproteinases and histone deacetylases. Some of these drugs have already entered preclinical and clinical testing with promising anti-tumor effects. These as well as even newer agents may offer exciting possibilities for the future treatment of thyroid cancer.
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2,339,088 |
SNP discovery and typing technologies for pharmacogenomics.
|
Genetic variation in the human genome occurs predominantly as single nucleotide polymorphisms (SNPs). Our DNA may contain as many as ten million SNPs, of which three million or more are likely to differ between any two unrelated individuals. These three million genetic differences make a significant contribution to the observed variation in complex human phenotypes, such as disease susceptibility and our responses to drugs or environmental chemicals. Large-scale association studies taking place throughout the drug development process can help to identify such differences and tailor drugs and dose regimens to particular genotype classes. The need for such large-scale studies has driven the development of high-throughout SNP discovery and typing technologies, which are the subject of this review.
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2,339,089 |
Genotyping as a tool to predict adverse drug reactions.
|
During the last decades, the rapid development in molecular biology has contributed to the understanding of genetic factors underlying many adverse drug reactions. Until recently, most research in this area has focused on genes coding for drug-metabolizing enzymes. Inactivating mutations have been found in genes coding for enzymes belonging to the cytochrome P-450 system, which is the major system for drug metabolism in humans, but also in genes coding for other enzymes. Subjects with a lack of functional activity in these enzymes should be treated with very low doses of drugs metabolized by the same enzyme in order to avoid excessive drug levels and thereby toxic effects. In the last years, increasing attention has been directed towards genes coding for drug targets. Hitherto, most studies have been carried out on single genes known to be or assumed to be functionally related to a given adverse drug reaction. Another approach, which may become more common in the future, is testing for complex single nucleotide polymorphism patterns that may be associated with adverse drug reactions, although the functional relationship between them may be completely unknown. Due to the influence of non-genetic factors in the development of adverse drug reactions, the association between a specific genotype and an adverse drug reaction will always be lower than 100%. Therefore, there is a need for prospective large-scale studies in order to elucidate the extent of environmental influences on the adverse drug reactions for which a genetic basis has been suggested. Despite these obstacles, pharmacogenetic testing will hopefully in the future identify at least some clear-cut situations where a drug should be avoided in certain individuals in order to reduce the risk of adverse drug reactions.
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2,339,090 |
"The lion, the witch and the wardrobe": impact on sibs of individuals with AAT deficiency.
|
Alpha(1)-antitrypsin (AAT) deficiency is a genetic disorder that may cause serious pulmonary or liver impairment in children or adults. Although genetic sequencing of the AAT gene has only been available for 20 years, analysis of the amount and electrophoretic mobility of the AAT protein has allowed clinical phenotyping for more than 40 years. There have been no studies assessing the psychological impact of having a sib affected by AAT deficiency. Twenty-five participants drawn from the Alpha-1 Research Registry completed a questionnaire and semi-structured interview. Respondents were supportive of testing prior to adulthood for AAT status; 18 thought it was a good idea to test a child, three did not know, and four said children should not be tested, primarily citing insurance concerns. Of those 18 who stated it was a good idea, 14 would test at birth. Knowledge of genetics of AAT deficiency was limited; only 44% of respondents understood the inheritance pattern. We recommend: (1) parents and sibs need help in mourning the loss of children with AAT deficiency; young sibs are at risk for trauma and long-term developmental problems. (2) Teams evaluating donors for liver transplantation should be aggressive in ruling out AAT deficiency prior to invasive testing. (3) Testing should be offered to individuals with a family history of AAT deficiency to obtain the health benefits of lifestyle modification and limit the burden of disease discovery in symptomatic relatives. (4) Awareness of liver disease from AAT deficiency should be increased.
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2,339,091 |
BRCA1/2 testing in hereditary breast and ovarian cancer families: effectiveness of problem-solving training as a counseling intervention.
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It remains uncertain whether members of hereditary breast and ovarian cancer (HBOC) families experience psychological distress with genetic testing and whether pre-test counseling can have a moderating effect on client well-being. One purpose of this study was to assess change in psychological well-being from baseline to 6-9 months follow-up and the effect of a problem-solving training (PST) intervention on psychological well-being. Two hundred and twelve members of 13 HBOC families were offered BRCA1/2 testing for a previously identified family mutation. Participants received education and were randomized to one of two counseling interventions; PST or client-centered counseling. Psychological well-being was assessed at baseline and again at 6-9 months following the receipt of test results, or at the equivalent time for those participants who chose not to undergo testing. Well-being was assessed using measures of depressive symptoms (CESD), intrusive thoughts (IES), cancer worries, and self-esteem. Comparisons were made between those who chose testing and those who did not as well as between those who received positive and negative test results. One hundred eighty one participants elected to undergo genetic testing (85%) and 47 of these (26%) were identified as BRCA1/2 mutation carriers. Breast and ovarian cancer worries decreased significantly (p = 0.007 and 0.008, respectively) in those who tested negative while there was no appreciable change in psychological well-being from baseline to follow-up in either those who tested positive or in non-testers. Among all participants, particularly testers, those randomized to PST had a greater reduction in depressive symptoms than those randomized to client-centered counseling (p < 0.05 and p = 0.02, respectively). Regardless of the decision to test, individuals with a personal history of cancer (n = 22) were more likely to have an increase in breast cancer worries compared to those who had never been diagnosed with cancer (p < 0.001). Results suggest that a problem-solving counseling intervention may help to enhance psychological well-being following testing and that a personal history of cancer may increase psychological distress associated with genetic testing.
|
2,339,092 |
Exploratory study of the feasibility and utility of the colored eco-genetic relationship map (CEGRM) in women at high genetic risk of developing breast cancer.
|
We report here the results of an exploratory feasibility study of the colored eco-genetic relationship map (CEGRM), a novel, recently-developed psychosocial assessment tool, which incorporates features of the genetic pedigree, family systems genogram, and ecomap. The CEGRM presents a simple, concise, visual representation of the social interaction domains of information, services, and emotional support through the application of color-coded symbols to the genetic pedigree. The interactive process of completing the CEGRM was designed to facilitate contemporary genetic counseling goals of: (a) understanding the client in the context of her/his social milieu; (b) bolstering client self-awareness and insight; (c) fostering active client participation and mutuality in the counseling interaction; (d) eliciting illuminating social narratives; and (e) addressing outstanding emotional issues. Twenty women participating in a breast imaging study of women from families with BRCA1/2 mutations completed and evaluated various aspects of the CEGRM. We found that efficient construction of the CEGRM was feasible, and that compliance was excellent. Participants developed insights into their social milieu through observing the visual pattern of relationships illustrated by the CEGRM. The process of co-constructing the CEGRM fostered the participant's active involvement in the session, marked by mutuality and increased empathy. In this clinical research context, the participants felt free to share poignant stories about their friends and families. Further studies are planned to refine the CEGRM and to examine its utility in cancer genetics research.
|
2,339,093 |
Neurologic course, endocrine dysfunction and triplet repeat size in spinal bulbar muscular atrophy.
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To study the role of diabetes, gynecomastia and CAG triplet repeat size as disease modifying factors of neurologic expression in spinal bulbar muscular atrophy (SBMA, Kennedy's disease).</AbstractText>Twenty unrelated SBMA patients with confirmatory genetic testing were reviewed. Patterns of neurologic involvement were assessed (e.g. bulbar, asymmetric, proximal, distal, motor and sensory). Slopes of disease progression were calculated from serial quantified neurologic examinations. Patterns of neurologic involvement and course were correlated to the presence of diabetes, gynecomastia and triplet repeat size.</AbstractText>Diabetes or glucose impairment occurred in nine and 11 had gynecomastia. Patterns of neurologic involvement and rates of progression did not correlate with these endocrine diseases or triplet repeat sizes. Correlation was seen between number of CAG repeats and age of onset weakness (r = -0.53, r2 = 29%, p = 0.01).</AbstractText>The specific neurotoxic effect of expanded CAGs appears limited to age of onset weakness in SBMA. Although significant, only 29% of the variability in onset age could be accounted for by polyglutamine size suggesting the importance of other unidentified factors. In this series diabetes or glucose impairment was more common than previously reported and, like gynecomastia, did not correlate with size of triplet repeats, severity or patterns of neurologic involvement. Modifying factors other than diabetes, gynecomastia or triplet repeat size are suggested in disease expression.</AbstractText>
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2,339,094 |
Screen for genes differentially expressed during regeneration of the zebrafish caudal fin.
|
The zebrafish caudal fin constitutes an important model for studying the molecular basis of tissue regeneration. The cascade of genes induced after amputation or injury, leading to restoration of the lost fin structures, include those responsible for wound healing, blastema formation, tissue outgrowth, and patterning. We carried out a systematic study to identify genes that are up-regulated during "initiation" (1 day) and "outgrowth and differentiation" (4 days) of fin regeneration by using two complementary methods, suppression subtraction hybridization (SSH) and differential display reverse transcriptase polymerase chain reaction (DDRT-PCR). We obtained 298 distinct genes/sequences from SSH libraries and 24 distinct genes/sequences by DDRT-PCR. We determined the expression of 54 of these genes using in situ hybridization. In parallel, gene expression analyses were done in zebrafish embryos and early larvae. The information gathered from the present study provides resources for further investigations into the molecular mechanisms of fin development and regeneration.
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2,339,095 |
Comprehensive genetics clinic for familial tumors: proposal for a suitable system in Japan.
|
With the progress of the Human Genome Project, genetic testing has become widely available and useful in several kinds of familial cancer. As the results of the genetic testing may predict future onset of the disease and/or may influence other family members, clinical oncologists have to consider the psychological challenges and ethical complexities of communicating hereditary cancer risk information to families. A clinical genetics approach, including genetic counseling, is fundamental before and after the genetic testing. We introduce our activity at the Division of Clinical and Molecular Genetics, Shinshu University Hospital. Our system of a multidisciplinary approach to genetic counseling could be suitable for other hospitals in Japan.
|
2,339,096 |
Familial breast and ovarian cancers.
|
About 60% of familial breast and ovarian cancers in Japan involve germline mutations of the BRCA1 or BRCA2 ( BRCA1/2) genes. These genes contribute to genetic stability and DNA repair and act as tumor suppressor genes. Mutation analysis of the BRCA1/2 genes has improved our understanding of both common mutation patterns in Japanese patients and the clinicopathological features of BRCA1/2-related cancers. BRCA1-related breast cancers are characterized by poor prognosis, a low rate of estrogen receptor positivity, and histological predominance of solid-tubular carcinoma. BRCA1-related ovarian cancers are associated with a high frequency of serous adenocarcinoma and a good outcome. Further large-scale studies are needed to delineate genotype-phenotype relations and penetrance in BRCA1/2-related breast and ovarian cancers in Japan. The development of systems for clinical genetics in Japan, including genetic counseling, has led to the increased use of genetic testing for the clinical management of BRCA1/2-related cancers. Three options are available for carriers of BRCA1/2 mutations: intensive surveillance, chemoprevention, and prophylactic surgery. Studies done in other countries indicate that prophylactic surgery effectively prevents the development of breast and ovarian cancers in carriers of BRCA1/2 mutations. However, prophylactic mastectomy remains controversial in Japan, and now systematic intensive surveillance is generally performed for the prevention of breast cancer in women at high risk. Early detection of ovarian cancer remains challenging, resulting in increased acceptance of the need for prophylactic oophorectomy in women at risk. This review summarizes experimental and clinical findings about familial breast and ovarian cancers, including data on Japanese patients.
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2,339,097 |
Molecular genetic diagnosis of familial tumors.
|
Recent advances in molecular biology have identified the responsible genes for many hereditary cancer syndromes (familial tumors). Therefore, now, the final diagnosis of familial tumors can be done by molecular methods to detect the genetic alteration in the disease-causing responsible gene(s) in the patient. So-called "genetic testing" is now available, not only as the diagnosis in the proband but also as the pre-symptomatic carrier diagnosis for unaffected family members. However, a number of issues, including legal, ethical, social, psychological, economic, and technical ones, surround and inhibit the clinical application of this testing, especially in Japan. As for molecular analysis to detect possible mutation in clinical specimens, highly sensitive scanning and detection methods are indispensable for screening nucleotide substitutions, including point mutations and single-nucleotide polymorphisms (SNPs). Also, several methods have been developed to screen and confirm the genetic alterations in familial tumors. These analytical techniques for detecting genetic alterations are categorized into four types, involving (1) scanning of nucleotide substitutions, (2) detection of defined mutations or SNPs, (3) size determination, and (4) DNA sequencing. Each technique has its advantages and disadvantages, and the technique in each case should be selected according to the purpose of the analysis. In this article, the concept of molecular diagnosis in familial tumors and the related molecular methods are described.
|
2,339,098 |
Statistical methods of translating microarray data into clinically relevant diagnostic information in colorectal cancer.
|
It is a common practice in cancer microarray experiments that a normal tissue is collected from the same individual from whom the tumor tissue was taken. The indirect design is usually adopted for the experiment that uses a common reference RNA hybridized both to normal and tumor tissues. However, it is often the case that the test material is not large enough for the experimenter to extract enough RNA to conduct the microarray experiment. Hence, collecting n cases does not necessarily end up with a matched pair sample of size n. Instead we usually have a matched pair sample of size n1, and two independent samples of sizes n2 and n3, respectively, for 'reference versus normal tissue only' and 'reference versus tumor tissue only' hybridizations (n=n1 + n2 + n3). Standard statistical methods need to be modified and new statistical procedures are developed for analyzing this mixed dataset.</AbstractText>We propose a new test statistic, t3, as a means of combining all the information in the mixed dataset for detecting differentially expressed (DE) genes between normal and tumor tissues. We employed the extended receiver operating characteristic approach to the mixed dataset. We devised a measure of disagreement between a RT-PCR experiment and a microarray experiment. Hotelling's T2 statistic is employed to detect a set of DE genes and its prediction rate is compared with the prediction rate of a univariate procedure. We observe that Hotelling's T2 statistic detects DE genes more efficiently than a univariate procedure and that further research is warranted on the formal test procedure using Hotelling's T2 statistic.</AbstractText>[email protected].</AbstractText>
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2,339,099 |
A semiparametric approach for marker gene selection based on gene expression data.
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Identification of differentially expressed genes is a major issue in gene expression data analysis and selection of marker genes is critical in tumor classification using gene expression data. In this paper, we propose a semiparametric two-sample test to identify both differentially expressed genes and select marker genes for sample classification.</AbstractText>A simulation study shows that the proposed method is more robust and powerful than the methods, generally used such as t-tests and non-parametric rank-sum tests, when the sample size is small. Cross-validation shows that the sample classification based on genes selected using this semiparametric method has lower misclassification rates.</AbstractText>[email protected].</AbstractText>
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