A distinctive feature of CML is the reciprocal translocation, originating in hematopoietic stem cells (HSCs), between the long arms of chromosomes 9 and 22, i.e., t(9;22) (q34;q11.2), which results in the BCR-ABL1 chimeric gene. The gene discussed is ABL1; the disease is chronic myelogenous leukemia, BCR-ABL1 positive.