Sitosterolemia: Four Cases of an Uncommon Cause of Hemolytic Anemia (Mediterranean Stomatocytosis with Macrothrombocytopenia).

Sitosterolemia is a rare autosomal recessively inherited lipid metabolic disorder that is characterized by hyper absorption of plant sterols from the intestinal mucosa leading to toxic levels in the blood. Four patients of age ranging from 11 to 29 years presented to the outpatient department with clinical features of hemolytic anemia. There were no features of hypercholesterolemia in any of the patients. Peripheral smear examination of all four patients showed stomatocytes and macrothrombocytopenia. Qualitative testing for plant sterols was performed in one case. Next generation sequencing revealed a compound heterozygous mutation in ABCG5 gene (c.1222C>T and c.1255C>T) in one case and homozygous mutations in ABCG5 gene (c.727C>T), (c.332G>A (p.G111E)), (c.1222C>T) in the other three cases. Ezetimibe (10 mg/day) was administered in one case, with complete resolution of symptoms. All patients were advised a low plant sterol diet and regular monitoring of hemoglobin and lipid profile. Our cases highlight a rare but important cause of hemolytic anemia that can be suspected from careful peripheral blood examination but only conclusively established by molecular genetic diagnosis.