Red cell membrane abnormalities in two cases with a special type of a hereditary megaloblastoid hemolytic anemia.
Case reports are presented of two related patients suffering from a hereditary megaloblastoid hemolytic anemia which at the moment cannot be categorized into one of the well-known entities. The main characteristics of the disease consisted of constant jaundice, macrocytic normochromic anemia, marked hemolysis without a substantial decrease in osmotic resistance, increased iron turnover and hepatic hemosiderosis at a relatively young age. One patient had to undergo splenectomy due to hemolytic crises, the other one cholecystectomy due to gallstones. In contrast to their uncharacteristic morphology in smear, red cells displayed highly variable forms ("lumpy", "Y", "U", drumstick forms) when examined in transmission and scanning electron microscopes. These changes corresponded well with reduced filtrability and aggregability of erythrocytes. The apparent relative blood viscosity was unchanged. The protein pattern of ghosts in SDS gel-electrophoresis revealed neither defects nor additional bands. Changes in the lipid composition of the membrane were indirectly deduced from electron spin-resonance studies, which showed an additional signal at g = 2.192. Similarly, the lipid related membrane mobility agent A2C failed to exert the usual stabilizing effect against osmotic stress. The negative surface potential, estimated by free flow electrophoresis, was only altered in the splenectomized patient. It is concluded that the primary abnormal physical properties of the enlarged red cell contribute at least in part to the marked hemolysis. The similar findings in the two related patients and the fact that the disorder was obviously congenital suggest a special subtype of a megaloblastoid hemolytic anemia.