Relationship of endothelial nitric oxide synthase (eNOS) gene polymorphisms with diabetic retinopathy in Caucasians with type 2 diabetes

Abstract

Background: Nitric oxide synthesized by endothelial nitric oxide synthase (eNOS) plays a key role in the regulation of endothelial function, and controversial results regarding the association of eNOS gene polymorphisms with diabetic complications have been reported.

Materials and Methods: In this case-control study, the relationship of the −786T/C, the VNTR intron 4 a/b and the 894G/T (Glu298Asp) polymorphisms in the eNOS gene with the presence or severity of diabetic retinopathy was analyzed in 630 Caucasian-Brazilians with type 2 diabetes (434 with and 196 without diabetic retinopathy). Genotyping of eNOS polymorphisms was carried out using the PCR or PCR-RFLP method, and haplotype frequencies were estimated using a Bayesian method.

Results: Genotype and allele frequencies in patients with any degree of diabetic retinopathy or proliferative diabetic retinopathy were not significantly different from those of patients without this complication for all eNOS polymorphisms. Likewise, there were no differences in haplotype frequencies among diabetic patients with or without diabetic retinopathy (p values > 0.05 for all comparisons).

Conclusion: Our findings do not support the hypothesis that the −786T/C, the VNTR intron 4 a/b and the 894G/T (Glu298Asp) polymorphisms in the eNOS gene play a role in the pathogenesis of diabetic retinopathy in type 2 diabetes.

Keywords::

• Type 2 diabetes
• diabetic retinopathy
• endothelial nitric oxide synthase (eNOS)
• polymorphism

ACKNOWLEDGMENTS

The authors would like to thank Dr B. Tschiedel and Dr K.E.P. Souto and their team for kindly providing part of the sample of diabetic patients analyzed in this study. The authors are also grateful to Dr A. J. G. Ordóñez and Dr H. Yasue for gently providing detailed conditions of the PCR methodology used to genotype eNOS polymorphisms.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.