In chronic myeloid leukemia, what cytogenetic abnormality is commonly observed?

Chronic myeloid leukemia (CML) is characterized by a specific cytogenetic abnormality known as the Philadelphia chromosome, which is the result of a translocation involving chromosomes 9 and 22 (t(9;22)). This translocation causes the BCR-ABL fusion gene to form, which encodes a constitutively active tyrosine kinase. This active kinase plays a crucial role in the pathophysiology of CML by promoting cell proliferation and inhibiting apoptosis, leading to the accumulation of myeloid cells in the bone marrow and peripheral blood.

The presence of the Philadelphia chromosome is a key diagnostic marker for CML and is used to guide treatment options, including the use of targeted therapies such as tyrosine kinase inhibitors (e.g., imatinib) that specifically inhibit the BCR-ABL protein.

Other cytogenetic abnormalities mentioned, such as t(8;14), t(15;17), and t(11;14), are associated with different types of leukemia or lymphomas and are not characteristic of CML. Thus, the presence of the t(9;22) translocation is a definitive feature of chronic myeloid leukemia and highlights the importance of genetic testing in diagnosing and