Endothelial Nitric Oxide Synthase Gene Polymorphisms and the Risk of Diabetic Nephropathy in Type 2 Diabetes Mellitus

Endothelial dysfunction plays an important role in the pathogenesis of diabetic vascular disease, including diabetic nephropathy (DN). Endothelial nitric oxide synthase (eNOS) gene polymorphisms that affect eNOS activity are associated with endothelial dysfunction. The aim of this study was to evaluate the association of three polymorphisms of the eNOS gene (894G > T, -786T > C, and 27-bp-VNTR) with the risk of DN among type 2 diabetic patients. A total of 400 type 2 diabetic patients were enrolled in this study. The DN group comprised 200 patients; the group of diabetics without nephropathy comprised another 200 patients. Genetic analysis for eNOS gene polymorphisms was done in all subjects. Measurement of nitric oxide levels was estimated. The C allele for -786T > C and the T allele for 894G > T were significantly more frequent in diabetics with nephropathy than in diabetics without nephropathy (p < 0.001; odds ratio [OR] and 95% confidence interval [CI] for the C allele = 1.64 [1.24-2.17] and p < 0.001; OR and 95% CI = 1.7 [1.27-2.26] for the T allele). The haplotypes CTa (with all the mutant alleles) and CTb were significantly more common in patients with DN (p = 0.01 and 0.003, respectively). These results suggested that the eNOS polymorphisms might represent genetic determinants for developing DN in type 2 diabetic Egyptians.