eNOS polymorphisms on male infertility: An updated systematic review and meta-analysis

This meta-analysis was performed to examine the association of 3 endothelial nitric oxide synthase (eNOS) gene polymorphisms with male infertility. METHODS: The literature on the relation between the mutant of eNOS and male infertility before July 1, 2022, was conducted in Pubmed, Medline, and Web of Science. The search strategy is as follows: (eNOS OR ECNOS OR nitric oxide synthase 3 OR NOS3) AND (polymorphism OR mutation OR variation OR SNP OR genotype) AND (male infertility). Statistical analysis was performed with the web of MetaGenyo, Stata 12, trial sequential analysis 0.9Beta, and the web of GTEx. RESULTS: Overall, 13 studies (26 case-controls) were included involving 6518 cases and 5461 controls for 3 polymorphisms (rs2070744, rs1799983, rs61722009) of eNOS. We found that eNOS rs2070744 was correlated with an increased risk of male infertility (C vs. T: odds ratio [OR], 1.48; 95% confidence interval [CI], [1.19–1.85]; CC vs. TT: OR, 2.59; 95% CI, [1.40–4.80]; CT vs. TT: OR, 1.17; 95% CI, [1.00–1.38]; CC vs. CT + TT: OR, 2.50; 95% CI, [1.35–4.62]; CC + CT vs. TT: OR, 1.41; 95% CI, [1.21–1.64]). And eNOS rs1799983 was correlated with an increased risk of male infertility (allele contrast T vs. G: OR, 1.41; 95% CI, [1.01–1.96]; P = .043; recessive model TT vs. TG + GG: OR, 2.00; 95% CI, [1.03–3.90]; P = .042). In the stratified analysis of rs61722009, we found Asians might be correlated with an increased risk of male infertility (4a vs. 4b: OR, 1.50; 95% CI, [0.94–2.38]; 4a4a vs. 4b4b: OR, 2.56; 95% CI, [0.70–9.38]; 4a4b vs. 4b4b: OR, 1.36; 95% CI, [0.87–2.13]; 4a4a vs. 4a4b + 4b4b: OR, 2.57; 95% CI, [0.91–7.30]; 4a4a + 4a4b vs. 4b4b: OR, 1.44; 95% CI, [0.87–2.40]). CONCLUSION: The eNOS rs2070744 polymorphism and rs1799983 are associated with the risk of male infertility, and rs61722009 might be a risk factor for Asians.