Combined Effect of GSTT1 and GSTM1 Polymorphisms on Human Male Infertility in North Indian Population

Abstract

Genes of different pathways regulate spermatogenesis, and complexity of spermatogenic process indicates that polymorphisms or mutations in these genes could cause male infertility. Detoxification pathway is involved in the regulation of spermatogenesis by reducing oxidative stress and contributes to the maintenance of global methylation in concert with other pathways. Glutathione S-transferases (GSTs) belong to the family of phase II antioxidant enzymes involved in the cellular detoxification of various physiological substances. Glutathione S-transferases act as an antioxidant and protect spermatozoa from oxidative stress. Increase in the levels of reactive oxygen species (ROS) along with reduced activity of GSTs may result in sperm membrane damage and DNA fragmentation. A case-control study was done to elucidate the role of deletion polymorphism of GSTT1 and GSTM1 genes from GSTs family on idiopathic human male infertility. The study comprises 2 groups: 113 nonobstructive azoospermia patients and 91 healthy fertile controls. Genomic DNA was analyzed by polymerase chain reaction for GSTT1 and GSTM1 genes. The study showed statistically significant protective association of GSTT1 null genotype with human male infertility (odds ratio [OR]: 0.3, 95% confidence interval [CI] 0.143-0.9966, P = .048) but not with GSTM1 null genotype (OR: 0.66, 95% CI 0.3653-1.2234, P = .19). Also, combination of null genotypes of GSTM1 and GSTT1 confers protective effect (OR: 0.28, CI 0.0801-0.948; P = .04). Probably, individuals bearing GSTM1 and GSTT1 (-/-) genotypes may have protective effect by gene-gene interaction mechanism. In summary, our study underscores the significance of combined effect of GSTT1 and GSTM1 null genotypes in modulating the risk of male infertility.