Association between Glutathione S-transferase M1/Glutathione S-transferase T1 polymorphisms and Parkinson's disease: A meta-analysis

The Glutathione S-transferase M1 (GSTM1) and Glutathione S-transferase T1 (GSTT1) genes have been studied extensively as potential candidate genes for the risk of Parkinson's disease (PD). However, direct evidence from genetic association studies remains inconclusive. In order to address this issue, we performed an updated and refined meta-analysis to determine the effect of GSTM1 and GSTT1 polymorphisms on Parkinson's disease. A fixed-effect model was utilized to calculate the combined odds ratio (OR), OR of different ethnicities, and 95% confidence intervals (CIs). Potential publication bias was estimated. Homogeneity of the included studies was also evaluated. The pooled OR was 1.13 [95% CI (1.03, 1.24)] and 0.96 [95% CI (0.82, 1.12)] for GSTM1 and GSTT1 polymorphisms, respectively. Analysis according to different races found no association between GSTM1/GSTT1 polymorphisms and PD risks except for GSTM1 variant in Caucasians, which showed a weak correlation (OR 1.16 [95% CI (1.04, 1.29), I squared = 6.2%, p = 0.384]). Neither publication bias nor heterogeneity was found among the included studies. The results of this meta-analysis suggest that GSTM1 polymorphism is weakly associated with the risk of PD in Caucasians whereas GSTT1 polymorphism is not a PD risk factor.