Sitosterolemia Due to a New Combination of ABCG8 Variants Presenting as Hemolytic Anemia and Macrothrombocytopenia

Sitosterolemia is a rare, autosomal recessive lipid disorder caused by mutations in adenosine triphosphate-binding cassette subfamily G member 5 or 8 (ABCG5/8), leading to excessive absorption and systemic accumulation of plant sterols. Patients typically present with xanthelasma, tendon xanthomas, premature atherosclerosis, and hematologic abnormalities. We report a case of sitosterolemia in a man presenting with hemolytic anemia, macrothrombocytopenia, and hypercholesterolemia. Genetic testing revealed a novel combination of ABCG8 variants, expanding the known spectrum of pathogenic mutations associated with this condition. The patient was treated with statin, ezetimibe, and low plant sterol diet, and after 9 months his plasma sterol levels improved.