A BCR–JAK2 fusion gene as the result of a t(9;22)(p24;q11.2) translocation in a patient with a clinically typical chronic myeloid leukemia

✍ Scribed by Frank Griesinger; Heike Hennig; Frauke Hillmer; Martina Podleschny; Rainer Steffens; Andreas Pies; Bernhard Wörmann; Detlef Haase; Stefan K. Bohlander

• Publisher: John Wiley and Sons
• Year: 2005
• Tongue: English
• Weight: 216 KB
• Volume: 44
• Category: Article
• ISSN: 1045-2257
• DOI: 10.1002/gcc.20235

✦ Synopsis

Abstract

Chronic myeloid leukemia (CML) is characterized by the presence of a t(9;22)(q34;q11.2), which leads to the well‐known BCR–ABL1 fusion protein. We describe a patient who was diagnosed clinically with a typical CML but on cytogenetic analysis was found to have a t(9;22)(p24;q11.2). Chromosomal fluorescence in situ hybridization showed that the BCR gene locus spanned the breakpoint at band 22q11.2 but that the ABL1 gene was not rearranged. By means of a candidate gene approach, the JAK2 gene, at 9p24, was identified as the fusion partner of BCR in this case. The BCR–JAK2 fusion protein contains the coiled‐coil dimerization domain of BCR and the protein tyrosine kinase domain (JH1) of JAK2. The patient's disease did not respond to Imatinib, and this unresponsiveness was most likely a result of the BCR–JAK2 fusion protein. © 2005 Wiley‐Liss, Inc.