Apolipoprotein E phenotypes in hyperlipidaemic patients and their implications for treatment.
Apolipoprotein E phenotypes were determined on 417 consecutive lipid clinic patients using an isoelectric focussing technique. Of the 15 patients with phenotype E2/2, 13 (3.1%) had type III hyperlipoproteinaemia and 2 obese identical twins had type V. A further 20 patients (4.8%) had similar plasma and lipoprotein lipid levels but were E2 heterozygotes (14 E3/2 and 6 E4/2). They displayed a widened pre-beta-band almost confluent with the beta-band rather than the broad beta-band shown in classical E2/2 type III patients. In view of the similarities between these heterozygotes and the classical homozygous (E2/2) type III patients and their occurrence in the same families we suggest the nomenclature homozygous and heterozygous type III. In a subsequent comparison between 30 E2/2, 22 E3/2 and 8 E4/2 type III individuals the only significant difference in plasma and lipoprotein lipid parameters was a lower VLDL cholesterol to triglyceride ratio of 0.85 in E3/2 patients than that of 1.24 in E2/2 patients (P less than 0.01). Both homozygous and heterozygous patients showed premature ischaemic heart disease and both responded dramatically and similarly to treatment with clofibrate. These observations indicate that apo E phenotyping is worthwhile in all patients with combined hyperlipidaemia and that homozygous and heterozygous type III hyperlipoproteinaemia is not uncommon.
D000328:Adult; D000368:Aged; D001057:Apolipoproteins E / Q000097:blood / Q000235:genetics*; D002784:Cholesterol / Q000097:blood; D015243:Cholesterol, VLDL; D002994:Clofibrate / Q000627:therapeutic use; D004200:Diseases in Twins; D005260:Female; D006579:Heterozygote; D006720:Homozygote; D006801:Humans; D006949:Hyperlipidemias / Q000097:blood / Q000188:drug therapy / Q000235:genetics*; D006952:Hyperlipoproteinemia Type III / Q000097:blood / Q000188:drug therapy / Q000235:genetics; D006954:Hyperlipoproteinemia Type V / Q000097:blood / Q000188:drug therapy / Q000235:genetics; D007525:Isoelectric Focusing; D008074:Lipoproteins / Q000097:blood; D008079:Lipoproteins, VLDL / Q000097:blood; D008297:Male; D008875:Middle Aged; D014430:Twins, Monozygotic
D001057:Apolipoproteins E; D015243:Cholesterol, VLDL; D008074:Lipoproteins; D008079:Lipoproteins, VLDL; D002784:Cholesterol; D002994:Clofibrate