Distribution of DD Genotype of Angiotensin-Converting Enzyme Gene and Its Correlation with Diabetic Retinopathy

One of the major microvascular complications of diabetes mellitus (DM) is diabetic retinopathy (DR). Studies have shown that angiotensin-converting enzyme (ACE) gene polymorphisms are correlated with DR progression. Accordingly, the elucidation of the association between ACE gene polymorphism and the risk of DR development seems to be highly crucial.

In this study, 195 individuals with type 2 diabetes mellitus (T2DM) were classified as the case group with retinopathy (99 people) and control group without retinopathy (96 people). Screening for DR was performed by ophthalmologists using clinical examination and fluorescein angiography. Different ACE genotypes (II, ID, and DD) were identified by the collection of blood samples, extraction of DNA, and PCR amplification using specific primers.

The frequency distribution of genotypes was significantly different between the case and control groups (P = 0.009). Interestingly, possessing a DD genotype made diabetic patients approximately 2.5 folds (95% CI = 1.271 - 4.840, P = 0.007) and 3.25 folds (95% CI = 1.312 - 8.051, P = 0.01) more susceptible to DR when compared to having DI and II genotypes, respectively. Moreover, having a D allele made diabetic individuals nearly 1.75 folds (95% CI = 1.167 - 2.623, P = 0.007) more susceptible to DR than possessing an I allele.

Our results potentiate the hypothesis that the DD genotype and D allele of the ACE gene might play a role in the pathogenesis of DR.