BCR/ABL(ABL1) Translocation, Dual Fusion
- ABL1, 9q34.11-q34.12, Red
- BCR, 22q11.22-q11.23, Green
The BCR/ABL1 probe mix contains a 169kb green probe centromeric to the BCR gene and covers the genes GNAZ and RAB36. A second green probe covers a 148kb region that includes the telomeric end of the IGLL1 gene and the flanking region beyond. A red probe covers a 346kb region that includes the ABL1 gene. There is an additional red probe that covers a 173kb region and spans the whole ASS1 gene.
The BCR (BCR activator of RhoGEF and GTPase) gene is located at 22q11.23 and the ABL1 (ABL proto-oncogene 1, non-receptor tyrosine kinase) gene is located at 9q34.12. Translocation between these two genes gives rise to the BCR-ABL1 fusion gene, and produces a Philadelphia chromosome; the visible result of this translocation.
The presence of a BCR-ABL1 fusion has important diagnostic and prognostic implications in a number of haematological disorders.
The t(9;22)(q34.12;q11.23) translocation is the hallmark of chronic myeloid leukaemia (CML) and is found in around 90-95% of cases1. The remaining cases have a variant translocation, or have a cryptic rearrangement involving 9q34 and 22q11.23 that cannot be identified by routine cytogenetic analysis1.
The BCR-ABL1 fusion can also be found in 25% of adult acute lymphoblastic leukaemia (ALL) and in 2-4% of childhood ALL1. The presence of a BCR-ABL1 fusion has been shown to confer a poor prognosis in ALL in both adults and children1,2. The detection of the abnormality is therefore of high importance for risk stratification, which will influence treatment and management decisions2. In a small number of ALL cases, the translocation does not result in a cytogenetically visible Philadelphia chromosome. In these cases, FISH is essential for highlighting the fusion gene3.
This rearrangement is also seen in rare cases of acute myeloid leukaemia (AML). Philadelphia-positive AML is characterised by its resistance to conventional standard chemotherapy and poor prognosis4, so accurate and rapid identification of this chromosomal abnormality is vital.
The quality of the products we have received from Cytocell have been excellent. The FISH probes they provide to us give intense, strong signals and are a pleasure to count. What has really stood out however has been the level of support and assistance provided by Cytocell’s application specialists. The team worked very closely alongside our own during the adoption of this product and spent many hours with us perfecting the technique, going above and beyond what I would expect during the transition period. Source BioScience absolutely demand high quality products and service to be able to deliver our results with confidence, and that is what we have received from Cytocell. Neil Ryan, Laboratory Operations Manager, Source BioScience
- Swerdlow et al., editors, WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues, Lyon,France, IARC:2008
- Harrison et al., BJH 2010;151:132-142
- Van Rhee et al., Br j Haematol 1995;90:225-8
- Soupir et al., Am J Clin Pathol 2007;127:642-650
- Arsham, MS., Barch, MJ. and Lawce HJ. (eds.) (2017) The AGT Cytogenetics Laboratory Manual. New Jersey: John Wiley & Sons Inc.
- Mascarello JT, Hirsch B, Kearney HM, et al. Section E9 of the American College of Medical Genetics technical standards and guidelines: fluorescence in situ hybridization. Genet Med. 2011;13(7):667-675.
- Wiktor AE, Dyke DLV, Stupca PJ, Ketterling RP, Thorland EC, Shearer BM, Fink SR, Stockero KJ, Majorowicz JR, Dewald GW. Preclinical validation of fluorescence in situ hybridization assays for clinical practice. Genetics in Medicine. 2006;8(1):16–23.
- Area of Interest*
- ALL, CML
This product is intended to be used on Carnoy’s solution (3:1 methanol/acetic acid) fixed haematological samples.
*Disease information supported by the literature and is not a reflection of the intended purpose of this product.