XL t(8;9) PCM1/JAK2 DF consists of an orange-labeled probe hybridizing to the PCM1 gene region at 8p22 and a green-labeled probe hybridizing to the JAK2 gene region at 9p24.

Probe maps are created in accordance with the intended purpose of the product. Solid colored bars do not necessarily indicate that the probe fully covers the indicated genomic region. Therefore, caution is advised when interpreting results generated through off-label use. Probe map details based on UCSC Genome Browser GRCh37/hg19. Map components not to scale. Further information is available on request.

Receptor tyrosine kinases as well as Janus kinases (JAKs) have multiple functions in the signal transmission of cytokines and growth factors. Furthermore, constitutively enhanced JAK phosphorylation levels play critical roles in chronic inflammatory processes and cancer development. Chromosomal rearrangements involving JAK2, leading to constitutive activation of the kinase, have been detected in several patients with myeloproliferative neoplasm (MPN) or myelodysplastic syndrome (MDS). While ETV6-JAK2 and BCR-JAK2 fusion genes, resulting from translocations of the type t(9;12)(p24;p13) and t(9;22)(p24;q11), respectively, have been reported only in a small number of patients, pericentriolar material 1 (PCM1)-JAK2 represents the most frequent JAK2 fusion gene. The responsible translocation generating the described fusion is t(8;9)(p22;p24.1). Multiple breakpoints have been identified.
In 2017, the WHO updated the category 'myeloid/lymphoid neoplasms with eosinophilia and gene rearrangement' by adding a provisional entity, PCM1-JAK2. All mentioned neoplasms described in this category are associated with rearrangements or (rarely) mutations of four tyrosine kinases: PDGFRA, PDGFRB, FGFR1 or JAK2, respectively. As PCM1-JAK2 fusions are associated with a poor prognosis, only allogeneic hematopoietic stem cell transplantation is considered to be rather successful, although first small studies using the JAK2 inhibitor ruxolitinib as treatment for patients with PCM1-JAK2 positive chronic eosinophilic leukemia, not otherwise specified, have shown promising short term remission.

Clinical Applications

• Chronic Myelogenous Leukemia and Myeloproliferative Neoplasms (CML/MPN)

XL t(8;9) PCM1/JAK2 DF hybridized to bone marrow cells, one aberrant cell is shown. A translocation t(8;9) has occurred generating a signal pattern of two colocalization/fusion signals, one green and one orange signal.

• Lierman et al (2012) Blood 120:1529-1531
• Rumi et al (2013) J Clin Oncol 31:e269-e271
• Reiter and Gotlib (2017) Blood 129:704-714