BCR-ABL1 refers to a gene sequence found in an abnormal chromosome 22 of some people with certain forms of leukemia.
Unlike most cancers, the cause of chronic myelogenous leukemia (CML) and some other leukemias can be traced to a single, specific genetic abnormality in one chromosome.
The presence of the gene sequence known as BCR-ABL1 confirms the diagnosis of CML and a form of acute lymphoblastic lymphoma (ALL), specifically a type of B-lymphoblastic leukemia/lymphoma. In very rare cases, the abnormal chromosome is linked to cases of acute myeloid leukemia and T-lymphoblastic leukemia/lymphoma.