Philadelphia chromosome

The Philadelphia chromosome is an abnormality in some cancer cells, especially in chronic myeloid leukemia (CML). It occurs when parts of two chromosomes, 9 and 22, swap places in a process called a translocation. This creates a new, abnormal chromosome (the Philadelphia chromosome) that produces a protein promoting unchecked cell growth. This abnormality is a key marker for diagnosing CML and helps guide targeted treatments that specifically block the faulty proteins, controlling the disease effectively.