The genetic feature in CML is the formation of Philadelphia (Ph) chromosome by the translocation between Chromosomes 9 and 22, which results in the expression of the BCR-ABL fusion gene (the C terminus of the proto-oncogene kinase ABL juxtaposed to the N terminus of the BCR)2,3. This evidence concerns the gene ABL1 and chronic myelogenous leukemia, BCR-ABL1 positive.