Mutations of SCN1B in Generalized Epilepsy with Febrile Seizures Plus(GEFS+).

Purpose : Febrile seizures affect 2-5% of all children younger than 6 years olf. A small proportion of children with febrile seizures later develop epilepsy. Generalized epilepsy with febrile seizures plus(GEFS+) is an important childhood genetic epilepsy syndrome with heterogeneous phenotypes, including febrile seizures(FS) and generalized epilepsies of variable severity. It was reported that the gene locus for GEFS+ exists in the chromosome 19q13.1, and has relationship with a 387 C→G mutation in the voltage-gated sodium channel β1 subunit(SCN1B) gene. This study is to determine whether there are mutations in children with GEFS+ and FS. Methods : Eighteen GEFS+ and thirteen FS patients were screened for mutations in the sodium channel beta-subunits SCN1B. The primer pairs used to amplify the exons of SCN1B are given in the supplementary data on the Neurology web site. All exons were amplified by PCR and PCR products were subsequently sequenced. Single-stranded conformation polymorphism(SSCP) was carried out using 8% polyacrylamide gel. Results : Twenty four patients(77%) were younger than 10 years old, three(10%) were between 10 and 14 years old, and four(13%) older than 14 years old. The ratio of female to male was 0.55:1.0 In phenotypes of GEFS+, fourteen patients(88%) had generalized tonic-clonic seizures, one patient(6%) myoclonic seizures and one patient(6%) atonic seizures. In EEG findings of GEFS+, eleven(78%) patients had normal findings, five(28%) patients generalized spike waves and two patients(11%) diffuse slowings. In sequencing and SSCP of PCR products, we could observe added C mutations between 224G and 225C of exon 3 in two unrelated patients with GEFS+. Conclusion : We proved the existence of a new mutation of SCN1B in two unrelated patients with GEFS+.ope