The glutathione-S-transferase gene polymorphisms (GSTM1 and GSTT1) and idiopathic male infertility risk: a meta-analysis.

Published data on the association between male infertility and the glutathione-S-transferase (GST) gene polymorphism are inclusive. To drive a more precise estimation, we performed a meta-analysis based on 1897 cases and 1785 controls from 15 published case-control studies. PubMed and CBMdisc literature research were conducted to identify all eligible studies investigating such a relationship. Crude odds ratios (ORs) with 95% confidence intervals (CIs) were calculated to estimate the strength of the association. In the overall analysis, the frequency of glutathione-S-transferase Mu-1 (GSTM1) null genotype was significantly associated with susceptibility to idiopathic male infertility. In further stratified analysis by sperm concentration of the case group, no significantly increased risk of azoospermia was found in either GSTM1 null or glutathione-S-transferase Theta-1 (GSTT1) null genotype. Compared with a significant relationship between GSTM1 null genotype and oligoasthenoteratozoospermia (OAT), GSTT1 null genotype was not associated with the OAT risk. Additionally, a subgroup analysis on ethnicity showed no notable association between the polymorphism and the risk of idiopathic male infertility in any of GSTM1 null and GSTT1 null genotype, neither in Asian nor in European populations. In conclusion, these results support that the GSTM1 null genotype mainly contributes to idiopathic male infertility susceptibility, particularly to OAT.