ABCB1 G2677T/A polymorphism is associated with the risk of drug-resistant epilepsy in Asians

Pharmacogenetic factors may play an important role in drug-resistant epilepsy. The association between the non-synonymous polymorphism G2677T/A in the coding region of the ABCB1 gene, and the risk of resistance to anti-epileptic drugs (AEDs) in epilepsy remains controversial. The present study used a meta-analysis approach to assess the pooled association between this polymorphism and the risk of resistance to AEDs. We used several online libraries to identify suitable studies published before September 2014, and 15 studies (n=1773 drug-resistant, and n=2250 drug-responsive epilepsy cases) were selected for our analysis. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the strength of the association. Subgroup analysis was performed taking into account different ethnic groups. Our results suggest that ethnicity plays a role in the association between ABCB1 G2677T/A polymorphism and drug-resistant epilepsy. We found a significant association for Asians both under the codominant model TT vs. GG (OR=1.33, 95% CI: 1.05-1.69; P=0.019), and the allele model T vs. G (OR=1.13, 95% CI: 1.01-1.27; P=0.032). However, no association was observed for Caucasians in either the TT vs. GG (OR=0.85, 95% CI: 0.61-1.18; P=0.335), or the T vs. G (OR=0.93, 95% CI: 0.78-1.09; P=0.362) models. A cumulative meta-analysis showed that these results were robust. In conclusion, our analysis indicates that ABCB1 G2677T/A polymorphism may increase the risk of drug-resistant epilepsy in Asians.