Philadelphia Chromosome

The Philadelphia Chromosome, named after the city where it was first identified in 1960, is a chromosomal abnormality found in leukemic cells. It is caused by a reciprocal translocation of genetic material between chromosomes 9 and 22 and results in an abnormal fusion gene. This fusion gene, known as BCR-ABL, is responsible for most cases of Chronic Myelogenous Leukemia (CML) and is associated with a poor prognosis. The Philadelphia Chromosome also plays an important role in the diagnosis of CML and other malignancies and can be detected via cytogenetic and molecular tests. Treatment for CML has greatly improved due to the identification of the Philadelphia Chromosome, allowing for targeted therapies such as tyrosine kinase inhibitors (TKIs) to be used.