ABL (9q34)/BCR(22q11)-t(9;22)(q34;q11)

t(9;22)(q34;q11) denotes a reciprocal translocation between chromosomes 9 and 22 at bands q34 and q11. It creates the BCR‑ABL1 fusion gene (the Philadelphia chromosome), which encodes a constitutively active tyrosine kinase that drives chronic myeloid leukemia and some acute lymphoblastic leukemias. It’s detected by cytogenetics or PCR and treated with targeted tyrosine kinase inhibitors such as imatinib.

BCR-ABL1 positive means a genetic abnormality where parts of the BCR and ABL1 genes fuse (Philadelphia chromosome), creating an abnormal tyrosine kinase that drives uncontrolled white blood cell growth. It’s most commonly seen in chronic myeloid leukemia and some acute leukemias, detected by PCR or FISH, and is treated and monitored with targeted tyrosine kinase inhibitors to guide therapy.

Translocation 9;22 (the Philadelphia chromosome) is a reciprocal swap of parts of chromosomes 9 and 22 that creates the BCR-ABL fusion gene. This produces an abnormal tyrosine kinase that drives uncontrolled white‑blood‑cell growth, most commonly causing chronic myeloid leukemia and some acute lymphoblastic leukemias. It’s diagnostic and guides treatment with targeted tyrosine‑kinase inhibitors (e.g., imatinib).

Chronic myeloid leukemia (CML) is defined by the BCR‑ABL1 fusion (Philadelphia chromosome) in the vast majority of cases—over 95% are BCR‑ABL positive. A small minority (<5%) may be BCR‑ABL‑negative or have variant translocations. Routine molecular testing for BCR‑ABL guides diagnosis and targeted therapy, since presence of the fusion determines use of tyrosine kinase inhibitors.

Yes. Most people with chronic‑phase CML treated with modern tyrosine kinase inhibitors achieve deep, durable remissions and often have near‑normal life expectancy. Early diagnosis, strict medication adherence, regular monitoring, and timely treatment changes are key. Some patients can later attempt treatment‑free remission under close supervision. Outcomes are worse in advanced phases, so prompt care and follow‑up are essential.

BCR-ABL is the Philadelphia‑chromosome fusion gene most commonly linked to chronic myeloid leukemia (CML). It is also present in a subset of acute lymphoblastic leukemia (Philadelphia‑positive ALL) and can appear in blast‑phase CML or, rarely, in acute myeloid leukemia. Detection of BCR‑ABL directs diagnosis and targeted treatment with tyrosine kinase inhibitors.