tokens: Results Affected individuals shared a 3.36 - Mb region of autozygosity on chromosome 22q12.2 , including a 10 - bp deletion ( NM_014338.3 : c.904 - 12_904 - 3delCTATCACCAC ) , immediately upstream of the last exon of the PISD ( phosphatidylserine decarboxylase ) gene .