Philadelphia chromosome or Philadelphia translocation is a specific chromosomal abnormality that's associated with chronic myelogenous leukemia (CML). It is the result of a reciprocal translocation between chromosome 9 and 22, and is specifically designated t(9;22)(q34;q11). The presence of this translocation is a highly sensitive test for CML, since 95% of people with CML have this abnormality (the remainder have either a cryptic translocation that's invisible on G-banded chromosome preparatio… (More on Bcr-abl)