Study of erythrocytes in a hereditary hemolytic syndrome (HHS): comparison with erythrocytes in lecithin:cholesterol acyltransferase (LCAT) deficiency.

Erythrocyte membrane abnormalities in 3 members of a family with a hereditary haemolytic syndrome (HHS) were compared to those previously described in a family with lecithin:cholesterol acyltransferase (LCAT) deficiency. Despite similarities including an increase in membrane phosphatidylcholine, a decrease in phosphatidylethanolamine, stomatocytosis, and a marked decrease in erythrocyte osmotic fragility a number of differences were observed. These included membrane cholesterol content (increased in homozygotes with LCAT deficiency), changes in sodium and potassium content and Na+,k+-ATPase activity (the latter being increased in HHS), changes in acetylcholinesterase and sulfhydryl group latency (present in LCAT deficiency, but not in HHS) and 2,3 DPG content (decreased in HHS, normal in LCAT deficiency. Full compensation of the erythrocyte defect occurred in HHS but the homozygotes for LCAT deficiency were slightly anaemic. It is concluded that, although similar abnormalities in phospholipid composition, osmotic fragility, and erythrocyte morphology exist in these two disorders, the molecular nature of the erythrocyte membrane structural and functional changes in HHS and LCAT deficiency is clearly different.