Apolipoproteins and atherosclerosis. Apolipoprotein E and apolipoprotein(a) as candidate genes of premature development of atherosclerosis

Apolipoprotein E (apoE) is a plasma lipoprotein which plays a basic role in the degradation of particles rich in cholesterol and triglycerides. It is able to bind to LDL receptors, but also to receptors for chylomicron remnan ts. There are three major apoE, isoforms, E2, E3, and E4. Their role in lip oprotein metabolism is related to their affinity for receptors. Allele E3 i s predominant and apoE3 affects metabolism of lipoproteins in a standard wa y. When compared to allele E3, allele E2 is associated with lower LDL level s, whereas allele E4 with higher LDL levels. This has an impact on the prog ression of atherosclerosis. Allele E2 exhibits a protective role, whereas a llele E4 is associated with a high risk factor. Lipoprotein(a) [Lp(a)] is a plasma lipoprotein, consisting of apolipoprotein(a), linked by a covalent bond with the LDL particle. Increased Lp(a) levels are associated with an i ncreased incidence of diseases based on atherosclerosis, namely the ischemi c heart disease. Another effect of Lp(a) is its competition with plasminoge n, resulting in a decrease of fibrinolysis and thrombogenic activity. ApoE and Lp(a) are independent risk factors for premature development of atheros clerosis and therefore can be considered as candidate genes of premature at herosclerosis.