The role of endothelial nitric oxide synthase (eNOS) T-786C, G894T, and 4a/b gene polymorphisms in the risk of idiopathic male infertility.

A considerable number of infertile men have no known mechanism for their infertility. This study aims to examine if there is an association between endothelial nitric oxide synthase (eNOS) T-786C, G894T, and 4a/b gene polymorphisms and idiopathic male infertility. Three hundred fifty-two men with idiopathic infertility (mean age 32.4 +/- 11.4 years) and 356 healthy controls (mean age 33.2 +/- 11.6 years) with documented fertility were recruited in this study. Genotypes for T-786C, G894T, and 4a/b gene polymorphisms were identified by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis. The eNOS -786CC genotype (0.310 vs. 0.081; odds ratio (OR), 3.64; 95% confidence interval (CI), 2.28-4.46; P = 0.001), 894TT genotype (0.131 vs. 0.006; OR, 3.62; 95% CI, 2.68-4.87; P = 0.001) and 4aa genotype (0.128 vs. 0.009; OR, 2.82; 95% CI, 1.88-3.89; P = 0.004) were significantly more frequent in infertile subjects. Furthermore, there was a significant difference between the group of infertile patients with azoospermia and oligoasthenoteratozoospermia (OAT) when compared by genotype distribution (-786CC vs. 786TT, 894TT vs. 894GG, and 4aa vs. 4bb) (all P < 0.01). We also found an association between the eNOS "-786C," "894T," and "a" alleles and an increased risk of poor semen parameters. Our data revealed a significant relationship between eNOS genotypes and the phenotype of infertility.