The Philadelphia (Ph) chromosome formed by the translocation of chromosomes 9 and 22, namely t(9;22), is closely related to disease, and the recombined Breakpoint cluster region-Abelson (BCR-ABL1) fusion gene encodes an oncoprotein with strong tyrosine kinase activity that is a key factor contributing to CML pathogenesis. The gene discussed is ABL1; the disease is chronic myelogenous leukemia, BCR-ABL1 positive.