Family B was a large multigenerational family, comprising 10 affected individuals, among which 7 patients had simple FS occurring between age 13 and 24 months. All patients had normal development. Two half brothers (B/IV-7 and B/IV-9) presented focal seizures in childhood with no history of FS. EEG and clinical features suggested benign rolandic epilepsy. Patient B/IV-5 presented at age 6 years a single brief afebrile GTCS 2 days after a fall while cycling with loss of consciousness of 10–15 minutes, suggesting a possible posttraumatic event. After the fall, her brain CT scan was normal and EEG 1 month after the accident was normal; she received no treatment. Gene panel sequencing identified a heterozygous nonsense mutation (c.406C>T, p.Arg136*, exon 4) in GABRG2 in the index case (B/III-10). Subsequent Sanger sequencing revealed that the p.Arg136* mutation segregated with the FS component and was absent in the 2 individuals with focal seizures without FS (B/IV-7 and B/IV-9) and in individual B/IV-5 with a single GTCS and no FS.
