Multidrug resistance gene 1 C1236T polymorphism and susceptibility to leukemia: A meta-analysis

Several studies have investigated the association between multidrug resistance gene (MDR1) C1236T polymorphism and leukemia risk, however, these published studies have yielded conflicting results. Thus, the present study carried out a meta-analysis to provide a more precise estimate of the effect of this polymorphism on the susceptibility to leukemia. The published case-control studies regarding the association between MDR1 C1236T polymorphism and leukemia risk were included following a computerized search of PubMed, Elsevier, The Cochrane Library, China National Knowledge Infrastructure and Wanfang Database. Either fixed- or random-effects models were applied to calculate the combined odds ratios (ORs) and 95% confidence intervals (CIs) by RevMan 5.2 software. Seven studies, including 846 cases and 1,523 controls, were included in the present meta-analysis. The results indicated that there was no significant association between the MDR1 C1236T polymorphism and leukemia risk in overall comparisons in all four genetic models (CT vs. CC: OR, 1.31, 95% CI, 0.89-1.91, P=0.17; TT vs. CC: OR, 2.16, 95% CI, 0.99-4.70, P=0.05; TT vs. CC+CT: OR, 1.72, 95% CI, 0.91-3.25, P=0.09; and CT+TT vs. CC: OR, 1.57, 95% CI, 0.96-2.56, P=0.07). In the subgroup analysis according to specific ethnicity, age and the type of leukemia, a significant association was found in adult leukemia (CT+TT vs. CC: OR, 2.77, 95% CI, 1.05-7.31, P=0.04) and chronic myeloid leukemia (CT vs. CC: OR, 1.71, 95% CI, 1.05-2.80, P=0.03). No significant publication bias was detected by funnel plot. Therefore, the meta-analysis indicated that the MDR1 C1236T polymorphism may contribute to the susceptibility to adult leukemia and chronic myeloid leukemia. Furthe well-designed studies based on larger sample sizes are required to validate these findings.