CML is consistently associated with the chromosomal translocation of t(9;22), which is called the "Philadelphia chromosome" or BCR-ABL1 mutation. The detection of the abnormal chromosome can be performed by karyotyping, fluorescent in situ hybridization (FISH), or gene mutation techniques. The BCR-ABL1 fusion gene is found in all myeloid cells as well as some lymphoid cells and is necessary for the diagnosis of CML.
Patients with untreated CML transform from the chronic phase (CP) to the accelerated phase (AP) and the blastic phase (BP) with a median survival of 2-3 years. The fusion gene (BCR-ABL) produces an oncoprotein with enzyme activity called "tyrosine kinase". This enzyme (tyrosine kinase) plays a major role in disease pathogenesis and cell proliferation. The discovery of the specific tyrosine kinase inhibitor (Imatinib or Gleevec) has dramatically improved the survival time for CML patients.
