Chronic myeloid leukemia (CML) is a myeloproliferative neoplasm of hematopoietic cell origin.It arises from the translocation of chromosomes 9 and 22, with resultant Philadelphia (Ph<sup>+</sup>) chromosome that contains the BCR-ABL1 gene.<sup> </sup>CML has three phases: the chronic phase, the accelerated phase, and blast crisis. The gene discussed is ABL1; the disease is chronic myelogenous leukemia, BCR-ABL1 positive.