Association between apolipoprotein E polymorphisms and premature coronary artery disease: a meta-analysis

Background: Although several studies have explored the genetic polymorphisms of apolipoprotein E (APOE) and their impact on premature coronary artery disease (PCAD), there is still some controversy regarding the significance of their association. Our aim is to estimate the association between APOE polymorphisms and PCAD via meta-analysis. Methods: All relevant case-control studies and cohort studies published in Chinese or English prior to March 2016 were searched for in electronic databases. Detailed information concerning each piece of literature was independently extracted by two researchers. We used STATA11.0 to process all data and to determine the pooled odds ratio (OR). Altogether, four genetic models were applied to calculate OR and 95% confidence interval (CI): (1) epsilon 2 allele vs. epsilon 3 allele; (2) epsilon 2 carriers vs. epsilon 3/3; (3) epsilon 4 allele vs. epsilon 3 allele; (4) epsilon 4 carriers vs. epsilon 3/3. Results: Eighteen studies concerning APOE polymorphisms and their impact on PCAD were included in the final analysis. The pooled analysis displayed that the epsilon 2 allele and epsilon 2 carriers increased the risk of PCAD significantly among Asians (OR 1.54; 95% CI, 1.09-2.17; OR 1.65; 1.10-2.47), while they showed protective effects on PCAD in Caucasians (OR 0.77; 95% CI, 0.62-0.95; OR 0.69; 0.54-0.89). Subjects with the epsilon 4 allele and epsilon 4 carriers showed significant associations with PCAD (OR 1.62; 95% CI, 1.27-2.06; OR 1.65; 1.27-2.15). Conclusions: Our investigation supported the fact that the epsilon 2 allele in APOE may appear as a risk factor for PCAD in Asians while a protective factor in Caucasians and that the epsilon 4 allele acted as a genetic risk factor for PCAD.