Single Nucleotide Polymorphisms of SCN1A-exon 9 in GEFS+

ABSTRACT

PURPOSE: Febrile seizures affect 2-5% of all children younger than 6 years old. A small proportion of children with febrile seizures later develop epilepsy. Muations in the voltage-gated sodium channel subunit gene SCN1A have been associated with febrile seizures(FSs) in autosomal dominant generalized epilepsy with febrile seizures plus (GEFS+) families and severe myoclonic epilepsy of infancy. The present study assessed the role of SCN1A in familial typical FSs. METHODS: 22 GEFS+ and 62 FSs were selected throughout a collaborative study of Catholic Child Neurology Research Group. The exon 9 region of SCN1A was screened by DHPLC. DNA fragments showing variant chromatograms were subsequently sequenced. RESULTS: A total 84 individuals(22 GEFS+ and 62 FSs) was screened for mutations. Among 22 GEFS+ and 62 FSs patients, five and forty nine showed simple FSs, and seventeen and thirteen had complex FSs. 0% and 8.3% were younger than 12 months old, 22.7% and 46.8% were between 12 and 35 months old, 18.2% and 41.9% were between 36 and 83 months old, and 59.1% and 0% were older than 84 months old. The ratios of male to female were 1.751 and 1.821. Mutational analysis detected no mutation of SCN1A. Mutational analysis detected eleven silent exonic polymorphisms at G1212A in exon 9 and forty two polymorphisms on intron 9, and 23 intron A/As in 73 homozygote samples. There were no significant differences in allelic frequencies(G/G intron A/A or G/G, G/G intron G/A, G/A intron G/A, reported G/A) of G1212A in SCN1A-exon 9 between the patients with GEFS+ and FSs(31.8% vs. 32.3%, 54.5% vs. 54.8%, 9% vs. 6.5%, 4.5% vs. 6.5%). CONCLUSION: Although our study demonstrated that SCN1A is not frequently involved in GEFS+ and FSs, further systemic research would be necessary.