Mediterranean stomatocytosis: A possible red cell membrane defect

Abstract

Stomatocytes are red cells in which the usual central pale area becomes elongated, so that the cell has the appearance of a pair of lips forming a mouth. In cases referred to as showing 'stomatocytosis' more than 10% of the red cells are stomatocytes. The authors searched for such cases over 18 mth., after one of them had gained the impression that stomatocytosis was frequently seen in Mediterranean migrants to Australia. The haematological investigation of 50 such cases was described and included family studies which suggested its inheritance as an autosomal dominant. Thirty-five had haemoglobin concentrations within the normal range, the remainder having mild to moderate anaemia, the lowest haemoglobin being 8g./100 ml. The anaemia appeared to be haemolytic in type. Thrombocytopenia was observed in 20 of 30 cases where platelet counts were performed, varying from 38- to 130,000mm.³. Reticulocytes varied from 2.2 to 7.4% in 19 of 26 cases, and slight splenomegaly in 10 out of 13 cases examined. Splenectomy was undertaken in one anaemia case with good result. Most patients presented to their doctors with a variety of complaints, none of which were clearly haematological. Acyltransferase activity was measured in 3 cases and significant reduction observed. It is possible that stomatocytosis may be caused by an abnormal red cell lipid partem resulting at least in part from a lowered level of acyltransferase. However, incubation of normal compatible red cells for 24hr. with plasma from patients with stomatocytosis did not induce stomatocyte formation and conversely stomatocytosis was not reversed when incubated for 24hr. at 37° in normal plasma. The plasma and red cells of 6 cases were analysed for sodium and potassium concentration and no evidence was found of the increased potassium/sodium flux across the red cell membrane such as has been described in two previously published studies of stomatocytosis.