BCR/ABL(ABL1) Plus Translocation, Dual Fusion
- ABL1, 9q34.11-q34.12, Red
- BCR, 22q11.22-q11.23, Green
- ASS1, 9q34.11-q34.12, Blue
The BCR/ABL1 probe mix contains a 169kb green probe centromeric to the BCR gene and contains the genes GNAZ and RAB36. A second green probe covers a 148kb region telomeric to the BCR gene and covers part of the IGLL1 gene. A red probe covers a 346kb region that spans the ABL1 gene. There is an additional blue 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, the ABL1 (ABL proto-oncogene 1, non-receptor tyrosine kinase) gene is located at 9q34.12 and the ASS1 (argininosuccinate synthase 1) gene is located at 9q34.11. Translocation between BCR and ABL1 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%1 of cases. The remaining cases have a variant translocation, or have a cryptic translocation between 9q34.12 and 22q11.23 that cannot be identified by routine cytogenetic analysis1. BCR-ABL1 fusions can also be found in 25% of adult acute lymphoblastic leukaemia (ALL) and in 2-4% of childhood ALL1. This rearrangement is also seen in rare cases of acute myeloid leukaemia (AML)2.
The translocation between chromosomes 9 and 22 can be accompanied by loss of proximal sequences on the derivative chromosome 9, including the ASS1(argininosuccinate synthase 1) region3. Concomitant ASS1 gene deletions have been associated with poorer prognosis in CML, although this may be partially abrogated by treatment with tyrosine kinase inhibitors (TKIs)4; therefore, the establishment of atypical patterns in patients with the BCR-ABL1 translocation may have clinical diagnostic and prognostic implications.
I first came across Cytocell FISH probes in a previous lab I worked in and I was struck by the quality of the products. Since this time, I have been recommending and introducing Cytocell probes across all application areas — now they are the primary FISH probes used in our lab. They have an excellent range of products and their ready-to-use reagent format saves considerable time. As a matter of fact, at a recent conference there was a discussion about the lack of commercial probes for a particular disorder and I was happy to point the participants in the direction of the Cytocell catalogue, which contains the exact probes required. Elizabeth Benner, Medical Technologist at the University of Arizona Health Network
- Swerdlow et al., (eds,) WHO Classification of Tumours of Haematopoietic and Lymphoid Tissue, Lyon, France, 4th edition, IARC,2017
- Soupir et al., Am J Clin Pathol 2007;127:642-650
- Robinson et al., Leukemia 2005;19(4):564-71
- Siu et al., BMC Blood Disorders 2009;9:4
- 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.