Philadelphia chromosome
Also written as: Ph — Philadelphia chromosome
A specific chromosomal abnormality found in chronic myeloid leukemia and some acute lymphoblastic leukemia cases.
Full Definition
The Philadelphia chromosome is an abnormal chromosome 22 that results from a translocation between chromosomes 9 and 22, designated as t(9;22). This translocation creates the BCR-ABL fusion gene, which produces an abnormal protein that drives the development of chronic myeloid leukemia (CML) and some cases of acute lymphoblastic leukemia. The presence of the Philadelphia chromosome is a key diagnostic marker and determines treatment approach, particularly the use of tyrosine kinase inhibitors.
Usage
Usage note: Always capitalize 'Philadelphia' when referring to the chromosome; Ph is acceptable abbreviation in clinical contexts.
In Context
- "The Philadelphia chromosome was detected in 95% of chronic myeloid leukemia patients." — Research publication
- "Ph-positive ALL requires different treatment protocols than Ph-negative disease." — Treatment protocol