The association of stomatocytic hemolysis and macrothrombocytopenia with sitosterolemia was revealed by Rees et al. In five pedigrees with these hematologic abnormalities they demonstrated the presence of both elevated levels of plant sterols in blood and mutations in ABCG5 and ABCG8, previously linked to sitosterolemia (47). The gene discussed is ABCG8; the disease is sitosterolemia.