Association of GSTM1 and GSTT1 Genes with the Susceptibility to Male Infertility: Result from a Meta-Analysis

The deletion polymorphisms of the glutathione S-transferase M1 (GSTM1) and glutathione S-transferase T1 (GSTT1) genes were considered as candidates for genetic susceptibility factors of male infertility. Previous studies concerning the relationship between the null genotype of the two genes and male infertility have been reported in recent years. However, the results remain elusive. A meta-analysis was performed to estimate the relationship between the deletion polymorphism of the GSTM1 or GSTT1 gene, and male infertility in this study. Sixteen studies concerning the GSTM1 gene, including 2174 cases and 1861 controls, and 13 case-control studies on the GSTT1 gene with a total number of 1992 cases and 1617 controls were processed. The results showed that the null genotype of the GSTM1 gene was associated with male infertility in the overall populations (P = 0.003, OR = 1.40, 95% CI = 1.12-1.75), especially in Caucasian (P = 0.012, OR = 1.50, 95% CI = 1.09-2.07) as well as Chinese (P = 0.001, OR = 1.55, 95% CI = 1.19-2.03). The null genotype of the GSTT1 gene was strongly related to male infertility only in Chinese (P = 0.000, OR= 1.70, 95% CI = 1.34-2.14). These results indicated that the null genotype of the GSTM1 gene might contribute to the susceptibility of male infertility, whereas the null genotype of the GSTT1 gene may be a genetic susceptibility factor of male infertility for the Chinese.