A Japanese family with high density lipoprotein deficiency.

Two siblings with marked reduction of plasma high density lipoprotein (HDL) were found in a Japanese family. Their plasma cholesterol levels were very low (30-60 mg/dl), especially in the HDL fraction (0-1 mg/dl). The concentration of apolipoprotein (Apo) A-I in their plasma was 2-3 mg/dl and that of Apo A-II was 1.5-2.0 mg/dl, determined by means of a single radial immunodiffusion technique. An ultracentrifugally separated HDL fraction contained two different populations of lipoprotein particles, as shown by electron microscopy; a small particle with a diameter of 50-70 A and a relatively large particle at 200 A. Plasma lecithin: cholesterol acyltransferase activity was substantially retained in both cases. Hepatosplenomegaly was present and liver biopsy revealed lipid deposition in reticuloendothelial cells, although the tonsils were apparently normal. No severe atherosclerotic lesions were noticed. The results from these two cases were consistent with the characteristic features of homozygotes of familial HDL deficiency (Tangier disease). HDL cholesterol levels were relatively low in the parents and two children from one patient, which is consistent with the heterozygote state. Two other cases in the kindred were also found to have relatively low HDL cholesterol levels, besides these 4 cases of obligate heterozygotes. Apo A-I and Apo A-II levels in the plasma of the obligate heterozygotes, however, were within the normal range. Plasma low density lipoprotein in the patients moved faster in polyacrylamide gel electrophoresis than those of normal subjects, as did those in the heterozygotes.