The biochemical, clinical, and genetic features of type III hyperlipoproteinemia.

The clinical and biochemical features of type III hyperlipoproteinemia are described in 49 patients from 23 to 70 years of age. An increase in very low-density lipoproteins (VLDL) of abnormal chemical composition was the basis for diagnosis. The untreated patients all had hypercholesterolemia and hyperglyceridemia, and, on the average, decreased concentrations of both low- and high-density lipoproteins. Seventy-four percent had xanthomas, and classic "xanthoma striata palmaris" was found in more than half. Twenty-seven percent had ischemic heart disease, detected earlier in men than in women. Twenty-seven percent had peripheral vascular disease (compared to 4% of subjects with type II hyperlipoproteinemia). Twenty-five of 35 subjects achieved normal lipid levels with dietary therapy alone. Analysis of 29 kindred showed hyperlipidemia in half of adult blood relatives; half of these had type III, the remainder usually had sample endogenous hyperglyceridemia (type IV). Only 2 of 55 children less than 20 years of age were affected, both with type IV.