ABSTRACT
Objective To determine the role of SCN1A gene variation in the development of familial febrile seizures (FS).Methods Clinical data were collected from 8 familial FS pedigrees, and peripheral venous blood samples were collected from the probands and other available family members. All 26 coding exons and exon-intron boundaries at least 50 bases of the human SCN1A gene were amplifled by polymerase chain reaction, the products were subsequently sequenced. To novo variation, other family members were screened for the corresponding exons. Two hundred age-matched healthy children were served as normal controls. ResultsA total of 33 variations in the SCN1A gene were identifled in these families. Of these variations, one was a missense mutation; the remaining 32 variations were previously submitted as single nucleotide polymorphisms (SNPs). A c.2650G>A heterozygous missense mutation in exon 15 of the SCN1A gene found in the proband of family 4 was inherited from his father who had seizures with fever in early childhood. The c.2650G>A mutation was absent in the 400 alleles of normal controls. To the best of our knowledge, the SCN1A c.2650G>A mutation has neither been reported in the NCBI SNP database nor in the literature to date. The c.2650G>A mutation changes a glycine at amino acid 884 in the SCN1A protein to a serine (p.Gly884Ser). Protein sequence analysis showed that the p.Gly884Ser is located at a highly conserved region between the 4th and 5th transmembrane segment of the homologous domain Ⅱ of voltage-gated sodium channel 1 subunit (DIIS4-S5). ConclusionsThe pathogenesis of familial febrile seizures was related to the SCN1A variation, the mutation outside the region of the voltage sensor (S4) and ion channel pore (S5-S6) of the voltage gated sodium channelα-subunit may be an important factor to cause mild phenotype epilepsy syndrome.