Apolipoprotein E polymorphism, paraoxonase-1 activity and coronary artery disease: is there a link

ABSTRACT

The association of ApoE allele frequencies with coronary artery disease [CAD] remains unknown in developing countries. Paraoxonase 1 [PON1] is an enzyme that is associated with high density lipoprotein [HDL] and hydrolyzes oxidized lipids in oxidized low density lipoprotein [LDL] and thus protects against the development of atherosclerosis. In this study the association of apoE polymorphism and PON1 with premature CAD was determined. The frequency of apo E alleles and the activity of the PON1 among 162 patients with early and late onset CAD was examined. The mean age in the early and late-onset groups were 44.9 ' 4.9 and 71.7'2.5 years respectively. Patients with early-onset CAD had significantly lower serum levels of HDL-C and higher LDL-C/HDL-C ratio than the late-onset group. There was no difference in serum levels of triglyceride, total cholesterol and LDL-C between the two groups. The e2 allele was significantly higher in the late-onset group. 35.0% of early-onset and 17.5% of late-onset group had low level of PON1. 86% of the early-onset CAD and all of the late-onset CAD patients with e3/ e4 genotype, had low or moderate level of PON1 activity. We found a positive association between PON1 activity, HDL level and the onset of CAD. Our study suggests that there are modest associations between CAD and apo E alleles and that the lower activity of PON1 in the presence of lower apo E level may increase the susceptibility to early-onset CAD