ABCB7 and cerebellar ataxia: A well-recognized candidate gene for MDS with the RS phenotype is the iron transporter ABCB7. Our group first reported marked downregulation of ABCB7 in MDS patients with RARS subtype.11 Hereditary X-linked sideroblastic anemia with ataxia is caused by partial loss-of-function mutations of ABCB7, which inhibit heme biosynthesis.12 Moreover, knockdown of ABCB7 in HeLa cells resulted in an iron-deficient phenotype with mitochondrial iron accumulation.13 Conditional gene targeting in mice has shown that ABCB7 is essential for hematopoiesis.12