The fact that one genetic event (JAKV617F) is associated to at least 3 different phenotypes and that IDH1, IDH2, ASXL1, RUNX1, DNMT3A, TET2, p53 and CBL mutations might be present in AML, MDS or MPN suggests that different molecular interactions between gene products result in specific malignant profiles. The gene discussed is RUNX1; the disease is myelodysplastic syndrome.