Introduction: Febrile seizures (FS) are the most common form of childhood seizures. Generalized epilepsy with febrile seizures plus (GEFS+) is an epileptic syndrome with autosomal dominant (AD) inheritance. GEFS+ is characterized by the incidence of FS persisting beyond the age of 6 years (defined as FS plus, FS+), which are followed in about one-third of patients by afebrile epileptic seizures. FS or FS+ are the only phenotypes described in around 70 % of GEFS+ probands. In approximately 10 % of cases GEFS+ syndrome is caused by mutations in SCN1A gene (coding for α1 subunit of neuronal voltage-gated sodium channel). The aim of the study: Due to well-known genetic background and frequent occurrence of FS phenotype in the GEFS+ patients the aim was to analyse the proportion of SCN1A mutations in patients with sporadic FS and AD inherited FS. Materials and methods: 50 FS probands and 50 healthy control subjects were included in the study. Clinical data from the total of 405 subjects were analysed. SSCP (Single-stranded conformation polymorphism) mutational analysis of all 26 exons of SCN1A gene was performed. Results: 35 FS probands came from families with AD inheritance. 15 probands had sporadic FS. No mutations in SCN1A gene were found. Conclusion: No significant clinical differences between probands with sporadic and familial FS were revealed. The SCN1A gene mutation is probably an insignificant etiological factor in FS.

        Key words: febrile seizures, genetics of epilepsy, α1 subunit of neuronal voltage-gated sodium channel, gene SCN1A, mutational analysis