Schematic representation of the multistep molecular pathogenesis of RARS-T supporting its nature of true MDS/MPN (combination of SF3B1 and JAK2 or MPL mutations). The occurrence of a somatic mutation of SF3B1 causes mitochondrial iron overload, ineffective erythropoiesis, and anemia, typical myelodysplastic features of RARS. The subsequent occurrence of a somatic mutation of JAK2 or MPL involves the acquisition of myeloproliferative features, including thrombocytosis. This hypothetical model is based on data still unpublished at the time of this writing.