To assess endothelial nitric oxide synthase (eNOS) gene polymorphism relationship with semen parameters and oxidative stress in infertile oligoasthenoteratozoospermic (OAT) men.

Three hundred subjects were divided into healthy fertile men (n = 80) and infertile OAT men (n = 220). They were subjected to history taking, clinical examination, and semen analysis in addition to malondialdehyde and glutathione peroxidase estimation in seminal plasma. Polymorphisms of eNOS G894T and T786C genotypes in peripheral blood were identified by the polymerase chain reaction–restriction fragment length polymorphism analysis.

Comparing infertile OAT men with fertile controls, eNOS genotype G894T demonstrated prevalence of 36.8% vs 50% for wild type (GG), 35.0% vs 47.5% for heterozygous type (GT), and 28.2% vs 2.5% for mutant homozygous type (TT). Compared with GG homozygotes, carriers with A allele exhibited >1.716-fold increased risk of OAT occurrence. Comparing infertile OAT men with fertile controls, eNOS genotype T786C demonstrated prevalence of 37.3% vs 51.3% for wild type (TT), 32.7% vs 45% for heterozygous type (TC), and 30% vs 3.7% for mutant type (CC) with significant differences. Compared with TT homozygotes, carriers with C allele exhibited >1.769-fold increased risk of OAT occurrence. G894T and T786C genotypes demonstrated significant negative correlation with sperm count, total sperm motility, sperm normal forms, and seminal glutathione peroxidase, and significant positive correlation with seminal malondialdehyde. G894T genotype demonstrated significant positive correlation with T786C genotype.

There is a significant relationship between eNOS genotypes T786C, G894T polymorphisms with decreased sperm parameters and increased seminal oxidative stress.