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Introduction Sitosterolaemia is a rare autosomal recessive disorder caused by mutations of ABCG5 and ABCG8, which leads to progressive accumulation of plant sterols within the body. We describe a patient with sitosterolaemia who presented with stoma-tocytosis and macrothrombocytopenia. Case report A pre-operative full blood count was checked on a 30-year-old Turkish woman (from parents as first degree cousin) with known history of idiopathic thrombocytopenia. Review of this blood film together with those from the past 2 years revealed a persistent picture of stomatocytosis and macrothrombocytopenia. Literature suggests these features can be from sitosterolaemia. There was history of migraine, oral contraceptive pill related acute hepatocellular hepatitis and hyperlipidaemia (total cholesterol 6.1 mmol/L, LDL-C 4.0 mmol/L, triglyceride 0.9 mmol/L - not on OC pills). There was no history of statin therapy and no family history of sitosterolaemia or premature cardiovascular diseases. Examination only revealed bilateral xanthelasma. Results Total plasma plant sterol was markedly raised (1.3 mmol/ L; NR Conclusions Sitosterolaemia can present exclusively with stoma-tocytosis and macrothrombocytopenia.1 Whether they represent a subgroup with a different prognosis is unknown.

The case described demonstrates the development of elliptical stomatocytosis in a neonate and the appearance of elliptical stomatocytes in her mother whose blood film, before delivery, showed elliptocytosis. Further investigations on both individuals indicated a mild haemolytic anaemia. To our knowledge this is the second reported case of elliptical stomatocytosis.

Two families with an unusual type of congenital hemolysis characterized by a normal to high hemoglobin, high reticulocyte count, the presence of target cells or small irregular cells on the peripheral blood smear, and bowl shaped cells in hypotonic wet preparations are described. The underlying abnormality appears to be an increased membrane permeability to both Na+ and K+, with consequent alteration of total cell cation and water content. Seven families previously reported are also reviewed. The entity is currently known as hereditary stomatocytosis with hydrated and dehydrated subtypes, but the diagnosis is frequently overlooked because of the variable morphology of the red cells, often without obvious stomatocytosis.

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 8 g./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 130,000 mm. 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 24 hr. with plasma from patients with stomatocytosis did not induce stomatocyte formation and conversely stomatocytosis was not reversed when incubated for 24 hr. 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.