Pharmacogenetic Impact on Korean Patients Receiving Antiepileptic Drugs

Epilepsy is the most prevalent chronic neurological disorder and can be controlled by antiepileptic drugs (AEDs) in up to 70% of patients. We performed an association study between adverse drug reactions and the genetic polymorphisms of CYP2C9, CYP2C19, ABCB1, and SCN1A. The clinical data of 83 epilepsy patients who had received AEDs containing carbamazepine (CBZ) were collected. We extracted genomic DNA from peripheral blood and then genotyped CYP2C9 (CYP2C9*2, CYP2C9*3), CYP2C19 (CYP2C19*2, CYP2C19*3), ABCB1 (C3435T), and SCN1A (IVS5N+5 G>A) using direct sequencing. The allele frequencies of CYP2C9*3, CYP2C19*2, CYP2C19*3, ABCB1 (3435C>T), and SCN1A (IVS5N+5 G>A) were 0.93, 0.72, 0.91, 0.61, and 0.55, respectively. Statistically significant differences were indicated from the data obtained. Patients with SCN1A genotype CC or CT were compared with patients with SCN1A genotype TT while using more than 500mg of carbamazepine. We have associated functional polymorphisms with the dose used in regular clinical practice for Korean epilepsy patients who had received antiepileptic drugs (AEDs) containing carbamazepine. For AEDs, we found that one of the SCN1A genotypes is associated with a 500 mg dose. There was no association found with CNS ADR caused by AEDs.