Association of idiopathic generalized epilepsy with polymorphisms in the neuronal nicotinic acetylcholine receptor subunits

Idiopathic generalized epilepsy (IGE) refers to a common group of epilepsies, and genetic factors play an important role in the pathogenesis of these disorders. Mutations in CHRNA4 and CHRNB2 are associated with some cases of familial epilepsies classified as autosomal-dominant nocturnal frontal lobe epilepsies. We aimed to evaluate whether polymorphisms of CHRNA4 and CHRNB2 are associated with IGE. A total of 75 children with IGE and 80 normal control subjects were included in the study. Each genetic polymorphism was typed by polymerase chain reaction (PCR)-based restriction analysis. The genotypes and allelic frequencies of each polymorphism were compared between the IGE patients and controls. The results showed that genotype and allelic frequency for CHRNB2 did not differ significantly between the groups. However, the genotype proportion of the CHRNA4 (Ser543Ser) gene in both groups was significantly different (P<0.0001). The T allele frequency was significantly higher (P=0.0126) in patients with IGE compared to healthy controls. The odds ratio (OR) for developing IGE in individuals with the CHRNA4 (Ser543Ser)-T homozygote was 4.9 (95% confidence interval (CI), 1.71-14.04) compared to individuals with two copies of the CHRNA4 (Ser543Ser)-C allele. This study demonstrates that the CHRNA4 gene may be one of the susceptibility factors for IGE.