Sitosterolemia Due to a New Combination of <i>ABCG8</i> 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 (<i>ABCG5/8</i>), 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 <i>ABCG8</i> 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.