Acquired hypolipoproteinemia

We present a six-year follow-up of a boy with a novel type of hypolipoproteinemia, with clinical and biochemical features distinct from classical hypoalphalipoproteinemias. There were abnormally low concentrations of total and high-density lipoprotein (HDL) cholesterol, apolipoprotein (apo) B, apo A-I, and apo A-II, and the phospholipids were decreased. The most striking abnormality was an extra fraction containing mainly phospholipids and apo A-I in the HDL3 subfraction. This fraction is reminiscent of concentric 20- to 50-nm-diameter lamellar phospholipid liposomes. Plasma lecithin:cholesterol acyltransferase activity was strongly decreased. We noted a persisting polyclonal hypergammaglobulinemia, hematological abnormalities (hemolytic anemia and thrombocytopenia), and a progressive splenomegaly. After the five-year follow-up, the patient had recurrent severe infections; moderate hematuria and proteinuria developed gradually. Treatment with corticosteroids and immunoglobulins improved thrombocytopenia and hypolipoproteinemia. These clinical and biochemical findings differ from those in the known primary and secondary hypo-alpha-lipoproteinemia syndromes. Although investigation of the relatives suggests a familial predisposition for hypo-alpha-lipoproteinemia, the subject's condition can be regarded as acquired.