Diabetic retinopathy: Validation study of ALR2, RAGE, iNOS and TNFB gene variants in a south Indian cohort

Abstract

Purpose: We previously reported the association of the Z-2 allele of the promoter dinucleotide repeat in the Aldose reductase (ALR2) gene, the (CCTTT)₁₅ allele in the promoter of inductible nitric oxide synthase (iNOS) gene, and the (GT)₁₃ promoter polymorphism in the tumor necrosis factor β (TNFB) gene with an increased risk for diabetic retinopathy (DR), and the Gly82Ser polymorphism in the receptor for advanced glycation end products (RAGE) gene and the (GT)₉ allele of the TNFB gene with low-risk for DR in a hospital-based self-reported type 2 diabetes mellitus (T2DM) patients. We have repeated the study in a population-based south Indian cohort to validate the same variations in these genes.

Materials and Methods: Type 2 diabetic patients with and without retinopathy (DR+ and DR− respectively) were recruited. (CA)_n repeat, Gly82Ser, (CCTTT)_n repeat and (GT)_n repeat in ALR2, RAGE, iNOS and TNFB genes respectively were genotyped and their frequencies were analyzed using the relevant statistical tests.

Results: Different allelic associations were observed in the present study as compared to our previous reports. Z+2 allele of ALR2, 13-repeat genotype of iNOS, 15-repeat genotype of TNF-β, genes were associated with susceptibility to DR. Gly82Ser polymorphisms of the RAGE gene were not associated with DR in the present study.

Conclusion: The present data show a difference in the association of variations in ALR2, iNOS and TNFB genes with DR, when compared to our previous reports; this could be attributed to differences between the study populations of the past and present report.

KEYWORDS::

• Diabetic retinopathy
• T2DM
• south India
• gene variations

ACKNOWLEDGMENTS

We thank RD TATA Trust, Mumbai, India for the financial grant and patients who participated in the study. We are very thankful to the Sankara Nethralaya Diabet*ic retinopathy project team for collecting the patients.

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