Associations between endothelial nitric oxide synthase polymorphisms and risk of diabetic nephropathy: an updated meta-analysis

Background: Genetic polymorphism of endothelial nitric oxide synthase (eNOS) has been implicated in the risk of diabetic nephropathy (DN), but the published findings were inconsistent. We performed a comprehensive meta-analysis to derive a more precise estimation of the association between genetic polymorphisms of eNOS and the risk of DN. Methods: Six online database were researched on the associations between polymorphisms of eNOS (T786C, G894T, 4b/4a) and DN risk. PRISMA statement and Hardy-Weinberg equilibrium assessment were used in this report. Odds ratio and 95% confidence interval were estimated based on the following genetic contrast/models: allelic model, dominant model, recessive model and co-dominant model. The publication bias and sensitivity analysis were also performed to guarantee the statistical power. Results: A total of 49 case-control studies with 11,990/9754/5131 participants for DN/DM/HC group were eligible for meta-analysis (7/25/31 studies for T786C/G984T/4b/a). For the eNOS-T786C, C allele showed a weak association between C allele and DN risk in DN/T2DM group. For eNOS-G894T, there was an association between T allele and DN risk in the global, Asian and African population in DN/T2DM group. For the eNOS-4b/4a, 4a allele was found contributing significantly to increased DN risk in the global population. Conclusion: Our comprehensive meta-analysis suggests that three polymorphisms of eNOS may be the increased risk factors of DN development, especially in Asian population and T2DM group.