tokens: PRRT2 was the most common single - gene epilepsy with an incidence of 1 per 9970 live births ( 10.0/100000 ; 95 % confidence interval 5.26 - 14.8 ) followed by SCN1A : 1 per 12 200 ( 8.26/100 000 ; 95 % confidence interval 3.93 - 12.6 ) ; KCNQ2 : 1 per 17 000 ( 5.89/100 000 ; 95 % confidence interval 2.24 - 9.56 ) and SLC2A1 : 1 per 24 300 ( 4.13/100 000 ; 95 % confidence interval 1.07 - 7.19 ) .