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.

背景：载脂蛋白E （APO-E）在脂质代谢和胆固醇转运中的作用是脂质代谢的关键组成部分，在诸如高胆固醇血症，糖尿病和心血管疾病等疾病中发挥作用。这项研究的目的是确定与冠状动脉疾病（CAD）患者中载脂蛋白E多态性相关的基因型，等位基因频率，基因表达和甲基化，并与南印度人群的非CAD健康受试者进行比较。

方法：采用PCR-RFLP技术检测APO-E等位基因和基因型。使用RT-PCR确定E3 / E3基因型的基因表达谱，并使用甲基特异性PCR测定法在100名患者和相同数量的对照中确定甲基化状态。

结果：鉴定出四种具有等位基因频率的APO-E基因型（E4 / E4，E3 / E3，E3 / E4和E2 / E3）。其中，发现E3 / E3基因型和E3等位基因在病例中显着高于对照。本研究表明，与对照组相比，E3 / E3基因型的CAD患者中APO-E的mRNA表达上调。甲基化状态表明E3 / E3基因型与该疾病显着相关。

结论：全世界研究的不同人群显示出APO-E等位基因和基因型固有的可变频率，最常见的等位基因是E3。在这项研究中，APO-E基因型E2 / E3 / E4对CAD表现出不同的反应，此外，E3 / E3基因型与CAD风险显着相关。该基因型可建议用于CAD诊断。