Increased prevalence of apolipoprotein E4 in type V hyperlipoproteinemia

Type V hyperlipoproteinemia (HLP) is characterized clinically by hepatosplenomegaly, occasional eruptive xanthomas, and an increased incidence of pancreatitis. These patients have striking hypertriglyceridemia due to increased plasma chylomicron and very low density lipoprotein concentrations in the fasting state, without a deficiency of lipoprotein lipase or its activator protein, apolipoprotein (apo) C-II. ApoE, a protein constituent of triglyceride-rich lipoproteins, has been implicated in the receptor-mediated hepatic uptake of these particles. ApoE has three major alleles: E2, E3, and E4, and the products of these alleles are apoE2, apoE3, and apoE4, respectively. ApoE phenotypes were determined in 30 type V HLP patients as well as in 37 normal volunteers. Among the type V patients, 33.3% were noted to be homozygous, and 40.0% heterozygous for E4 (normal, 2.7 and 21.6%, respectively). These data suggest that apoE4 may play a role in the etiology of the hyperlipidemia in a significant number of type V HLP patients.