Meta-analysis of the association between Apolipoprotein E polymorphism and risks of myocardial infarction

Background Myocardial infarction (MI) remains the leading cause of death and disability among cardiovascular diseases worldwide. Studies show that elevated low-density lipid protein cholesterol (LDL-C) levels confer the highest absolute risk of MI, and Apolipoprotein E (ApoE) is implicated in regulating levels of triglycerides (TGs), cholesterol, and LDL-C. Our study aimed to evaluate the association between APOE polymorphism and MI, and to provide evidence for the etiology of MI. Methods Case-control studies on the association between APOE polymorphisms and the risk of myocardial infarction were included by searching PubMed, Web of Science, and CNKI, and this meta-analysis was written in accordance with PRISMA guideline statement. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using either random-effects or fixed-effects models by R software. Results A total of 33 eligible articles involving 13,706 cases and 14,817 controls were finally selected. The pooled analysis based on the total eligible articles showed that the risk of MI was associated with ApoE epsilon 2 and epsilon 4 alleles. The results showed that patients with MI had a low frequency of the epsilon 2 allele (OR 0.74, 95% CI 0.64-0.86) and a high frequency of the epsilon 4 allele (OR 1.24, 95% CI 1.09-1.42). Conclusions APOE epsilon 2-involved genotypes may be protective factors for MI; in contrast, epsilon 4-involved genotypes (epsilon 4/epsilon 3 vs. epsilon 3/epsilon 3, and epsilon 4/epsilon 4 vs. epsilon 3/epsilon 3) may be risk factors for MI.