Inflammatory and oncogenic signaling converge in disease evolution of BCR-ABL-negative myeloproliferative neoplasms, clonal hematopoietic stem cell disorders characterized by gain-of-function mutation in JAK2 kinase (JAK2V617F), with highest prevalence in patients with polycythemia vera (PV).
One hundred five Philadelphia-negative MPN patients, including polycythemia vera (PV), essential thrombocythaemia (ET), and primary myelofibrosis (PMF) were initially screened for JAK2 mutations by amplification-refractory mutation system (ARMS-PCR) methodology and were further subjected to detection of CALR gene mutations by our in-house assay, a PCR based amplicon length differentiation assay (PCR-ALDA).
The V617F mutation in the JH2 domain of JAK2 is an oncogenic driver in several myeloproliferative neoplasms (MPNs), including essential thrombocythemia, myelofibrosis, and polycythemia vera (PV).
IPF analysis was performed on 22 patients with known JAK2V617F mutation and 41 patients who were negative for this mutation previously tested because of suspicion of PV.
In the absence of BCR-ABL, the conventional diagnostic algorithm recommends JAK2V617F mutation testing to support diagnosis of other MPN diseases such as polycythemia vera, essential thrombocythemia, and primary myelofibrosis.
The Janus kinase 2 (<i>JAK2</i>) V617F mutation is common in patients with breakpoint cluster region-Abelson1 (<i>BCR-ABL1</i>)-negative myeloproliferative neoplasms, including polycythemia vera, essential thrombocythemia and primary myelofibrosis, but is rarely detected in <i>BCR-ABL1-</i>positive chronic myeloid leukemia (CML) patients.
The advances in molecular insights, especially the discovery of the Janus kinase 2 (JAK2) V617F mutation and its role in JAK-STAT pathway dysregulation, led to the development of the JAK inhibitor ruxolitinib, which currently represents the cornerstone of medical therapy in MF and hydroxyurea-resistant/intolerant PV.
Aberrant JAK2 tyrosine kinase signaling drives the development of Philadelphia chromosome-negative myeloproliferative neoplasms (MPNs), including polycythemia vera, essential thrombocythemia, and primary myelofibrosis.
In addition, the presence of JAK2 mutation is expected in PV while approximately 90% of patients with ET express mutually exclusive JAK2, CALR, or myeloproliferative leukemia mutations.
JAK-STAT signaling dysregulation has been noted in inflammatory disorders, and aberrant JAK2 pathway activation has been implicated in myelofibrosis and polycythemia vera.
It has been observed that, during a course of disease, transformation from JAK2-mutated essential thrombocythemia (ET) to overt polycythemia vera (PV) can occur.
In this article, we report a unique patient with polycythemia vera driven by a rare complex in-frame deletion-insertion mutation in JAK2 exon 12, and CML driven by uncommon p210 e14a3 (b3a3) BCR/ABL fusion transcript.
Myeloproliferative neoplasms (MPNs), including polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF), are often characterized by specific somatic mutations in any of the three genes: JAK2, CALR, or MPL.
The whole body <sup>18</sup>F-FDG scan of a JAK2+ PV patient before treatment (a) as compared to a matched subject (b) is found below; of note is the PV patient's elevated uptake in the pelvis, femur and spine.
We further aim to investigate Jak2 exon 12 mutations in larger number of PV patients to assess their clinical relevance and role in disease onset, progression and transformation.