An abnormal chromosome 22 in which there is translocation of the distal portion of its long arm to chromosome 9. It is found in leukocyte cultures of many patients with chronic myelocytic leukemia. The Philadelphia chromosome was the first chromosomal change found to be characteristic of a human disease.
An atypical chromosome observed in individuals affected by a chronic type of leukemia, distinct from those with polycythemia vera (PV).
A genetic irregularity linked to a particular variant of leukemia. In this anomaly, a segment of one copy of chromosome 22 is absent; this section becomes detached and subsequently reattaches to a copy of chromosome 9.