Despite of a different pathogenic background for patients with MDS and CML-CP, such as occurrence of t(9;22)/BCR-ABL in CML and variety of chromosomal abnormalities in MDS, common cell phenotypic changes are shared by the aberrant myeloid progenitor cell clones in both MDS and CML during the advanced stage of malignant myeloid progression or so-called secondary AML (sAML). The gene discussed is ABL1; the disease is acute myeloid leukemia.