Apolipoprotein E isoform phenotyping methodology and population frequency with identification of apoE1 and apoE5 isoforms.

Minigel methodology has been utilized for apolipoprotein (apo) E isoform phenotyping and criteria for distinguishing the apoE4/4 phenotype (mean apoE4/apoE3 ratio: 5.81) from the apoE4/3 phenotype (mean ratio: 1.01) and the apoE3/3 phenotype (mean apoE3/apoE2 ratio: 2.67) from the apoE3/2 phenotype (mean ratio: 0.76) based on gel scanning were developed. ApoE allele frequencies in 1209 subjects were: apoE3, 0.786; apoE4, 0.135; apoE2, 0.075; apoE5, 0.002; and apoE1, 0.002. Subjects with the apoE2 allele tended to have higher plasma very low density lipoprotein (VLDL) cholesterol and lower low density lipoprotein (LDL) cholesterol concentrations than subjects with the apoE3 allele, while the converse was true for subjects with the apoE4 allele. Subjects with the rare apoE1 allele had values similar to those with the apoE2 allele, while subjects with the rare apoE5 allele had values similar to those with the apoE4 allele.