Association between ABCB1 C3435T polymorphism and antiepileptic drug resistance in epilepsy: An updated meta-analysis based on 62 studies

Objective: Previous clinical studies and meta-analyses have shown controversial results on the association be-tween C3435T polymorphism of the ABCB1 gene and anti-epileptic drug (AED) resis-tance. Based on the fact that sample size and confounding factors could contribute to the inconsistency, we performed an up-dated meta-analysis by including the most recent studies, and subgroup analysis was conducted to evaluate the effect of con-founding factors on the association. Mate-rials and methods: We searched articles in 6 electronic databases including PubMed, Medline, Embase, Web of science, Cochrane Library, CNKI (China National Knowledge In-frastructure) for relevant articles up to June 2020. Results: The current analysis showed that the C allele of C3435Tvariant was a risk factor for drug resistance in the overall pop-ulations (C allele vs. T allele, OR: 1.13; 95% CI: 1.02 - 1.25; p = 0.02) and in the Cauca-sians (C allele vs. T allele, OR: 1.09; 95% CI: 1.09 - 1.43; p = 0.002), while no association was observed in Asians and Indians. Particu-larly, our study reported for the first time that the 3435T allele was more common in epilepsy patients with drug resistance in the Tunisian population (C allele vs. T allele, OR: 0.31; 95% CI: 0.15 - 0.65; p = 0.002). In addi-tion, our present analysis suggested an asso-ciation between C3435T and AED resistance in cryptogenic, symptomatic, but not in idio-pathic patients. Subgroup studies based on age and gender showed no association. Con-clusion: AED resistance in Caucasian and Tu-nisian populations may benefit from ABCB1 C3435T genotyping. We recommend that more details, such as gender and etiology of epilepsy, should be taken into account to draw a reliable conclusion in future studies.