The Epsilon 2 and 4 Alleles of Apolipoprotein E and Ischemic Vascular Events in the Greek Population — Implications for the Interpretation of Similar Studies

Abstract

The authors investigated whether apolipoprotein (apo) E polymorphism has an allelic and/or genotypic impact on the risk of an ischemic vascular event (IVE) in Greek patients with cardio vascular diseases (CVD). They compared apo E polymorphisms in 1) a group of 165 patients with IVE [IVE(+)], of whom 107 had survived a myocardial infarction and 58 an ischemic stroke; 2) a group of 165 patients, matched with the first group for age and gender, with angio graphically confirmed coronary artery disease but without IVE [IVE(-)]; 3) a group of 240 healthy younger individuals with no family history of CVD. The apo ε2 allele was 5.2-fold less frequent in the IVE(+) group compared to the IVE(-) group (1.2% vs 6.2%, p= 0.001). The frequency of the ε2 allele in healthy subjects was 8.1 %, which is 6.7-fold higher than in the IVE(+) group (p < 0.001), and more than twice as high compared to all CVD patients (p = 0.001). No significant differences in ε4 allele frequencies were observed between IVE(+) and IVE(-) patients (9.8% vs 8.4%) or between patients with CVD and healthy subjects (9.1% vs 10.2%). The ε4 allele was not associated with an increased risk for CVD or IVE. In contrast, an inverse and beneficial association of the ε2 allele with IVE was observed among Greek patients with CVD. These results suggest that the ε4 and ε2 alleles have a variable significance in terms of predicting the risk of vascular events in different populations. Therefore, it is important to carry out "local" studies.