Which type of leukemia is characterized by the Philadelphia chromosome?

Chronic myeloid leukemia (CML) is particularly characterized by the presence of the Philadelphia chromosome, which results from a translocation between chromosome 9 and chromosome 22. This genetic alteration leads to the formation of the BCR-ABL fusion gene, which plays a critical role in the pathogenesis of CML by promoting uncontrolled cell division and survival of myeloid progenitor cells.

The presence of this chromosome serves as a significant diagnostic marker for CML and is associated with specific clinical features, treatment responses, and prognostic outcomes. Targeted therapies, such as tyrosine kinase inhibitors, have been developed to specifically address the effects of the BCR-ABL protein, revolutionizing the treatment of this leukemia.

Acute lymphoblastic leukemia (ALL), acute myeloid leukemia (AML), and chronic lymphocytic leukemia (CLL) are not typically associated with the Philadelphia chromosome. While ALL may sometimes have genetic mutations, it is not characterized by the Philadelphia chromosome in the same way that CML is. Thus, the identification of CML is crucial in clinical settings, reflecting its unique genetic underpinning and guiding effective treatment strategies.