Endothelial nitric oxide synthase VNTR (intron 4 a/b) polymorphism association with type 2 diabetes and its chronic complications

Subject and aims

Endothelial derived nitric oxide (eNOS) is involved in several functions playing important role in development of type 2 diabetes and insulin resistance. The aim of this study was to examine the association between eNOS intron 4 VNTR polymorphism and type 2 diabetes in an Iranian population.

Methods

A total of 220 patients with type 2 diabetes and 96 healthy control subjects were recruited from the same area. Genotyping was performed using PCR.

Results

A significant difference was found in genotype frequencies of eNOS polymorphism between patients and controls (aa + ab vs. bb p = 0.02, OR 2.0 95% CI; 1.05-3.96). Also allele a frequency was significantly increased in patients with diabetes compared with controls (p = 0.007, OR 2.1 95% CI; 1.19-4.08). We found that in patients with diabetic neuropathy the frequency of ‘a’ allele was significantly increased compared to the controls p = 0.03, OR = 1.8 95% CI (1.00-3.7). Both genotype and allele frequencies were significantly different between patients who were complication free compared to the controls [aa + ab vs. bb p = 0.007, OR = 2.6 95% CI (1.2-5.8) and p = 0.001, OR = 2.8 95% CI (1.4-5.9)] respectively with the a allele conferring the risk.

Conclusion

The association between eNOS VNTR polymorphism and T2DM seems to be stronger in patients without diabetic complications indicating diverse effect of eNOS polymorphism on diabetes and diabetic microvascular complications.