The French cohort consisted of 64 families with FS with or without epilepsy. All families were recruited through a national French campaign on genetic studies of familial FS conducted by Généthon in 1998–2000 (J.F. Prud'homme, Evry, France). Inclusion criterion for this cohort was the presence of at least 3 family members with FS (with or without associated epilepsy) with a transmission compatible with an autosomal dominant trait. Family members underwent clinical assessment using a detailed questionnaire. Information was also obtained retrospectively from medical records. Probands of all families were negative for SCN1A and SCN1B point mutations.
