In CML the BCR-ABL1 fusion gene, caused by a typical t(9;22)(q34;q11) chromosomal translocation, is the pathogenic driver of the disease leading to enhanced proliferation and left shift but also is used as a target to monitor minimal residual disease by quantitative reverse-transcription quantitative polymerase chain reaction (rt-PCR) analyses [28]. The gene discussed is BCR; the disease is chronic myelogenous leukemia, BCR-ABL1 positive.