Association between MDR1 C3435T polymorphism and refractory epilepsy in the Chinese population: A systematic review and meta-analysis

The association between the C3435T polymorphism in the MDR1 gene and refractory epilepsy remains controversial. The association appears to be influenced by ethnicity and region. We have performed a systematic review and meta-analysis to assess the link between the MDR1 C3435T polymorphism and refractory epilepsy in the Chinese population. We searched the Cochrane Library, MIDLINE, EMBASE, CBM disc, CNKI, VIP, and WANFANG databases for literature published through August 2013 for case-control studies that evaluated the association between the MDR1 C3435T polymorphism and refractory epilepsy. Twenty-one case-control studies involving 4269 patients (1863 cases in the group with drug-resistant epilepsy and 2406 in the group with drug-responsive epilepsy) were included in the systematic review and meta-analysis. The analysis showed that there were significantly more cases with the MDR1 3435 CC genotype in the group with drug-resistant epilepsy than in the group with drug-responsive epilepsy [odds ratio (OR) = 1.50, 95% confidence interval (CI) = 1.09-2.06, P = 0.01]. In a subanalysis of patients from the southern regions of China, the correlation was not significant [odds ratio (OR) = 1.2, 95% confidence interval (CI) = 0.89-1.64, P = 0.24]. The relationship established in a subset of the Chinese population between the MDR1 C3435T polymorphism and refractory epilepsy will guide epilepsy treatment and development of new AEDs.