Apolipoprotein E phenotypes in hyperlipidaemic patients and their implications for treatment

Area of Science:

• Biochemistry
• Genetics
• Cardiology

Background:

• Apolipoprotein E (Apo E) phenotypes are crucial in lipid metabolism.
• Type III hyperlipoproteinaemia is traditionally associated with the E2/2 phenotype.
• The prevalence and clinical significance of Apo E E2 heterozygotes require further investigation.

Purpose of the Study:

• To investigate the prevalence and characteristics of different Apolipoprotein E phenotypes in lipid clinic patients.
• To differentiate between homozygous (E2/2) and heterozygous (E3/2, E4/2) type III hyperlipoproteinaemia.
• To assess the clinical implications and treatment responses in these patient groups.

Main Methods:

• Isoelectric focusing technique for Apolipoprotein E phenotyping.
• Analysis of plasma and lipoprotein lipid levels.
• Clinical assessment of premature ischaemic heart disease.
• Evaluation of treatment response to clofibrate.

Main Results:

• 13.1% of patients with phenotype E2/2 had type III hyperlipoproteinaemia.
• 4.8% of patients were identified as E2 heterozygotes (E3/2 or E4/2) with similar lipid profiles but distinct electrophoretic patterns.
• Both homozygous and heterozygous type III patients exhibited premature ischaemic heart disease and responded well to clofibrate.

Conclusions:

• Apolipoprotein E phenotyping is valuable for patients with combined hyperlipidaemia.
• Homozygous and heterozygous type III hyperlipoproteinaemia are not rare and share clinical features.
• The findings support distinct nomenclature for homozygous and heterozygous type III hyperlipoproteinaemia based on Apo E phenotype.