The Philadelphia chromosome is a specific chromosomal abnormality that results from a translocation between chromosome 9 and chromosome 22. This translocation fuses the BCR gene from chromosome 22 with the ABL gene from chromosome 9, generating the BCR-ABL fusion gene. The resulting BCR-ABL protein is a potent oncogene, driving the pathogenesis of CML and, in some cases, acute lymphoblastic leukemia (ALL).
