A case of moderate hypertriglyceridemia with apolipoprotein E phenotype E4/3

Hyperlipoproteinemic subjects with apo(lipoprotein)E4 are usually hypercholesterolemic and those with apoE2 are hypertriglyceridemic. We report a case of moderate hypertriglyceridemia with apoE phenotype E4/3. Plasma levels of total cholesterol (TC), triglyceride (TG), high density lipoprotein (HDL)-C, apoAI, apoB, apoCII, apoCIII, and apoE were 200mg/dL, 451 mg/dL, 31 mg/dL, 115 mg/dL, 99 mg/dL, 10.0 mg/dL, 22.2 mg/dL, and 12.0 mg/dL, respectively. Plasma levels of very low density lipoprotein (VLDL)-C and intermediate density lipoprotein (IDL)-C were high, and those of low density lipoprotein (LDL)-C and HDL2-C were low. All lipoprotein subfractions except VLDL were TG-rich. These findings are common in moderate hypertriglyceridemia. The plasma level of remnant-like particle (RLP, equivalent to chylomicron remnant)-C, was high. The lipoprotein lipase which removes TG from chylomicron and VLDL was normal. The activity of LDL receptor which removes remnants of chylomicron and VLDL as well as LDL was high. ApoE4 actively binds to receptors of remnant and LDL. Thus, the removal of TG-rich lipoproteins should not be impaired in this patient. Plasma levels of insulin during oral glucose tolerance test were high. Hyperinsulinism stimulates VLDL synthesis in the liver. Subjects with apoE4 show active synthesis of chyromicron. Thus, we concluded that the moderate hypertriglyceridemia in this E4/3 patient was due to the overproduction of chylomicron and VLDL.