A Comprehensive Meta-Analysis: Unveiling the Link between Apolipoprotein E and Diabetic Retinopathy

Diabetic retinopathy (DR), a major diabetic microvascular complication, is a leading cause of visual loss. DR is often insidious and asymptomatic at the early stages. There has been a worldwide effort in the identification of key marker(s) that detect the disease before its onset. Apolipoprotein E (ApoE) gene has been suggested to be a potential risk factor for the development of micro- and macrovascular complications in diabetes. There are a few published reports available on the relationship between ApoE and DR; however, the outcome of these studies is inconsistent. Till date, there is no meta-analysis available on the association between ApoE and DR. Therefore, we have performed meta-analysis to achieve a more accurate conclusion regarding the relationship between ApoE genetic polymorphism and DR. Case-control studies analyzing ApoE polymorphism and DR were selected from databases, including PubMed and Google, as per the inclusion and exclusion criteria. Eligible data were extracted, pooled, analyzed, and evaluated using Comprehensive Meta-Analysis version-4. A total of five case-control studies were included, comprising 1,572 cases and 2,746 controls. The genotypes of ApoE were compared between cases and controls. Two genotypes, ɛ2ɛ2 and ɛ2ɛ3, were compared with ɛ2ɛ4 and ɛ3ɛ3. According to the analysis, there was no significant association between ApoE genotypic polymorphisms and DR (OR = 1.008, 95% CI = 0.702 -1.447, P = 0.967). In this meta-analysis, we found that ApoE polymorphisms were not associated with DR, suggesting that ApoE gene polymorphism does not determine genetic susceptibility of DR. Other genetic and environmental factors may be involved in DR development.