Polymorphism of apolipoprotein E

The two autosomal codominant alleles of the Apo E-N/D polymorphism, Apo En and Apo Ed, have a considerable influence on plasma lipid levels and distribution in man. Serum cholesterol levels are highest in phenotype Apo E-N, intermediate in phenotype Apo E-ND, and low in phenotype Apo E-D. Contrary VLDL-cholesterol is highest in phenotype Apo E-D, intermediate in heterozygotes, and lowest in phenotype Apo E-N. Serum-triglyceride, VLDL-triglyceride and the ratio of VLDL-cholesterol/serum-triglyceride are also intermediate in phenotype Apo E-ND between the two opposite homozygous groups. 10% of heterozygous Apo E-ND subjects exhibited a beta-VLDL subfraction compared to 0.8% in phenotype Apo E-N and 100% in Apo E-D. Hence the three phenotypic groups exhibit metabolic differences in vivo, and the gene Apo Ed has a mild dyslipoproteinemic effect even in a single dose. The Apo E-N/D polymorphism may therefore be a major influence on the occurrence of arteriosclerotic vascular disease in man.