Genetic and Epigenetic Factors of E3/E3 Genotypes of APO-E Gene as a Strong Predictor for the Diagnosis of Coronary Artery Disease Patients of South India

Background: The role of Apolipoprotein-E (APO-E) in lipid metabolism and cholesterol transport is a key component of lipid metabolism which plays a role in diseases like hypercholesterolemia, diabetes, and cardiovascular disease. The aim of this study was to determine the genotypes, allelic frequencies, gene expression and methylation related to apolipoprotein E polymorphism in Coronary Artery Disease (CAD) patients and compare with non-CAD healthy subjects of South Indian population. Methods: The APO-E alleles and genotypes were determined by PCR-RFLP. Gene expression profiles for E3/E3 genotypes were determined using RT-PCR and methylation status was determined using Methyl Specific PCR assay in one hundred patients and an equal number of controls. Results: Four APO-E genotypes (E4/E4, E3/E3, E3/E4, and E2/E3) were identified with different allele frequency. Among these, E3/E3 genotype and E3 allele were found to be significantly higher in cases than controls. The present study showed that the mRNA expression of APO-E was up-regulated in CAD patients with E3/E3 genotype in comparison with controls. Methylation status indicated a significant association of E3/E3 genotypes with the disease. Conclusion: Different populations studied worldwide showed inherent variable frequencies of the APO-E alleles and genotypes, with the most frequent allele being E3. In this study, the APO-E genotypes E2/E3/E4 showed variable response to CAD, further, there was a significant association of E3/E3 genotypes to CAD risk; this genotype can be suggested for the diagnosis of CAD.