Haemolytic anaemia in analpha‐lipoproteinaemia (Tangier disease): morphological, biochemical, and biophysical properties of the red blood cell

A patient with familial analpha-lipoproteinaemia (Tangier disease) was found to have stomatocytosis and haemolytic anaemia. The analysis of the red cell membrane constituents revealed a low cholesterol content (90 nmol/ml red cells, control 130 nmol/ml red cells), a decreased cholesterol/phospholipid ratio (0.54, control 0.78), high phosphatidylcholine (41.5%, control 30.6%) and low sphingomyelin (18.8%, control 27.6%). The electrophoretic membrane protein pattern was normal. Osmotic gradient ektacytometry and osmotic resistance showed a decreased surface/volume ratio, which caused an increased filtration resistance in 3 microns pores. The elasticity of the membrane was unchanged. Functional membrane properties were altered: the anion exchange rate was increased, whereas alkali cation fluxes were normal. The capacity to release vesicles was reduced. This case represented a new type of stomatocytosis. It contributes to the understanding of the role of cholesterol and phospholipids in the red cell membrane and biomembranes in general.