Improved Method for Genotyping Apolipoprotein E Polymorphisms by a PCR-Based Assay Simultaneously Utilizing Two Distinct Restriction Enzymes

Abstract

Apolipoprotein E (apo E) is a protein that plays an essential role in lipid metabolism and distribution (1). The apo E gene is polymorphic, and its three alleles code for isoforms E2, E3, and E4, which differ by single-amino-acid substitutions (2). The apo E3 allele is the predominant isoform in all populations studied. The apo E4 allele is associated with increased total serum cholesterol and greater odds for coronary heart disease (3); it also constitutes a major risk factor for Alzheimer disease (4). The apo E2 allele seems to have a protective effect against Alzheimer disease and is associated with longevity (5). Consequently, interest in examining individual patients and study groups for the apo E isoforms is growing. In this communication we describe a simple procedure that facilitates the genotyping of the apo E polymorphisms. In the common apo E3 polymorphism, TGC encodes for Cys112, and CGC encodes for Arg158. In the apo E2 another TGC codon results in Cys158, whereas in the apo E4 a different CGC codon gives rise to Arg112. The three apo E alleles …