Use of test
Translocations between Chromosome 9 and 22 resulting in fusion of the BCR and ABL1 genes can occur in a number of haematological malignancies, particularly chronic myeloid leukaemia (CML), and also acute myeloid leukaemia (AML) and acute lymphoblastic leukaemia (ALL). The identification of this gene fusion has diagnostic, prognostic, and therapeutic implications.
Presence of a BCR-ABL1 fusion gene in patients with CML is associated with response to targeted therapy by tyrosine kinase inhibitors such as imatinib, and good prognosis.
The presence of this fusion gene in patients with ALL or AML is associated with a poor prognosis.
FISH is typically used at diagnosis, as it can detect all possible breakpoints in the BCR and ABL1 genes, and if deletion of the nearby ASS gene has occurred. Quantitative PCR is used post-treatment to monitor for the presence of minimal residual disease, but FISH can be used if a suitable specimen for PCR is not available, or if the breakpoints are rare and not detected by quantitative PCR.
This is an assay for non-heritable mutations. It does not raise issues of ethics or consent that are different from most other investigations ordered in the routine care of a patient.
Fluorescent in situ hybridisation (FISH) analysis, using probes specific to the BCR and ABL1 genes. The breakpoints involved in these fusions can be variable, and in some cases certain variants will not be detected by the probe.
Requesting the test
This test is usually requested by a haematologist or oncologist.
0.5 mL bone marrow in transport media (or 5 mL blood in lithium heparin if blasts >10%).
To help ensure the quality of the test, a genetic test should be done with a dedicated sample whenever possible i.e. a sample collected specifically for that test rather than a sample that is used for multiple tests.
We recommend that the patient or another adult check the labelling of request forms and sample tubes.
1 business day.
This test has a Medicare rebate which, subject to the requirements of the Medicare descriptor being met, may cover all or part of the cost.
The Medicare details, including descriptor and schedule fee, are listed under MBS item 73314.