GABRG2 C588T Polymorphism Is Associated with Idiopathic Generalized Epilepsy but Not with Antiepileptic Drug Resistance in Pakistani Cohort

Abstract

Idiopathic generalized epilepsy (IGE) is the most prevalent type of epilepsy with genetic origin. Mutations in ion channel genes have been identified as a common cause of IGE. Several studies have reported various epilepsy risk variants of GABRG2 (gamma-aminobutyric acid type A receptor subunit gamma2 subunit) gene in different ethnic groups, but the results are inconsistent. The purpose of this case-control research is to determine if GABRG2 polymorphisms contribute to IGE susceptibility and antiepileptic drug resistance in Pakistani population. For this purpose, we genotyped exon2, exon5 (C540T and C588T), exon7 (T813C), exon8 (K289M), and exon9 of GABRG2 gene by restriction fragment length polymorphism and Sanger’s sequencing in 87 drug-responsive idiopathic generalized epilepsy patients, 55 drug-resistant epilepsy patients, and 83 healthy controls. Restriction fragment length polymorphism (RFLP) and sequencing results indicated only C588T polymorphism in the studied subjects. The comparison of genotypic and allelic frequencies showed significant differences between IGE patients and control groups ( $P=0.008$ and odds $\text{ratio}=4.2$ ) and nonsignificant association of C588T polymorphism in antiseizure medication-resistant patients ( $P=0.9$ ). Our findings showed that C588T polymorphism of GABRG2 is a risk variant for IGE in Pakistani population. Further studies are required to validate the results.