The t(9;22) translocation/BCR-ABL1 fusion gene is associated with chronic myeloid leukemia (CML) and “Philadelphia-positive” acute lymphoblastic leukemia of B-cell lineage (Ph+ ALL). Very rarely, this abnormality has also been identified in cases of acute myeloid leukemia and T-lymphoblastic leukemia/lymphoma.

BCR-ABL1 fusion genes possess substantial breakpoint heterogeneity at the DNA level, however, a consistent set of BCR-ABL1 messenger RNA (mRNA) transcripts are produced that can be readily and sensitively detected by reverse transcription-polymerase chain reaction  (RT-PCR) technique. In CML, breakpoints in BCR result in either exons 13 or 14 (e13, e14) joined to exon 2 of ABL1 (a2). The corresponding protein is 210-kDa in size, therefore identified as p210 variant. Rare cases of CML are characterized by an e19-a2 type mRNA with a corresponding p230 protein. In Ph+ ALL, the majority of cases harbor an e1-a2 BCR-ABL1 mRNA transcript, producing a p190 protein.

This assay can identify all three variants above, as well as rarer BCR-ABL1 transcript variants that have alternative break-fusion events such as e6-a2, and is, therefore, a comprehensive screen for both usual and uncommon BCR-ABL1 gene fusions in hematopoietic malignancies.

This assay is intended as a qualitative method, providing information on the presence (and specific mRNA type) or absence of the BCR-ABL1 mRNA. Results from this test can be used to determine the correct subsequent assay for monitoring of transcript levels following therapy