BCR and chronic myelogenous leukemia, BCR-ABL1 positive: Chronic myeloid leukemia (CML) is a myeloproliferative disorder that is genetically characterized by the translocation t(9;22)(q34;q11), which results in a BCR-ABLgene fusion on the derivative chromosome 22, called the Philadelphia chromosome (Ph).1,2Additional cytogenetic abnormalities are generally considered to be an important step in the evolution of CML from the chronic phase (CP) to the terminal blast crisis (BC).