Endothelial nitric oxide synthase polymorphisms and erectile dysfunction: a meta-analysis

Erectile dysfunction (ED) is a frequent disorder in men and has a serious impact on the quality of the patient's life. Recent studies have examined the relationship between endothelial nitric oxide synthase (eNOS) polymorphisms and ED. However, the results remain inconclusive. The present study aimed to offer an actual view of estimating the correlation between eNOS polymorphisms and ED.

We performed a meta-analysis to estimate the association between eNOS polymorphisms and ED risk. Databases employed for data mining until December 1, 2014 included PubMed, Web of Science, and the Chinese National Knowledge Infrastructure. Two study investigators independently conducted a literature search and data extraction. Odds ratios (ORs) with 95% confidence intervals for the risk were calculated by using a random effects model or fixed effects model.

A total of 20 studies in 13 publications increased ED risk in allele contrast, dominant, heterozygote, and homozygote models (allele contrast: OR = 1.514, 95% confidence interval were included in the meta-analysis. In the overall comparison, the eNOS G984T polymorphism was associated with an [CI]: 1.019-2.248). For 4 VNTR polymorphisms, the overall analysis showed a significant association between homozygote comparison and recessive genetic model (homozygote comparison: OR = 1.917, CI: 1.073-3.424). The eNOS T786C polymorphism increased ED risk in allele contrast, homozygote, and recessive models (allele contrast: OR = 1.588, CI: 1.316-1.915). Significant heterogeneity was mainly observed in studies on the G894T polymorphism. No publication bias was detected in all of the variants.

The eNOS polymorphisms G894T, 4 VNTR, and T786C were associated with an increased risk for ED. However, these results are still preliminary. Further studies based on different confounders and using a large population size should be conducted to generate more accurate and reliable conclusions.