Philadelphia chromosome
Pronunciation: fil-ah-DEL-fee-ah KROH-moh-sohm
An abnormal chromosome resulting from translocation t(9;22) that creates the BCR-ABL fusion gene, associated with certain leukemias.
Full Definition
The Philadelphia chromosome is an abnormal chromosome 22 that results from a reciprocal translocation between chromosomes 9 and 22, denoted as t(9;22)(q34;q11.2). This translocation creates the BCR-ABL fusion gene, which produces an oncogenic protein with constitutive tyrosine kinase activity. While most common in chronic myeloid leukemia, it also occurs in approximately 3-5% of pediatric acute lymphoblastic leukemia cases and is associated with poor prognosis. The discovery led to the development of tyrosine kinase inhibitors like imatinib.
Usage
Usage note: Capitalize 'Philadelphia' as it refers to the city where it was discovered. Can be abbreviated as Ph or Ph+.
In Context
- "Cytogenetic analysis revealed Philadelphia chromosome-positive acute lymphoblastic leukemia." — Laboratory report
- "Philadelphia chromosome-positive patients require tyrosine kinase inhibitor therapy." — Treatment guideline