Activating mutations in JAK2 are found in virtually all patients with polycythemia vera, and about half of those with essential thrombocythemia and primary myelofibrosis.
We examined whether lestaurtinib decreased JAK2-V617F allele burden and evaluated its clinical benefits and tolerability in patients with polycythaemia vera (PV) and essential thrombocythaemia (ET).
Bone marrow examination showed small and large megakaryocytes with dysplastic features in JAK2(V617F)-positive ET patients compared to those without JAK2(V617F).
In conclusion, in vitro cultures of haematopoietic progenitors are sensitive diagnostic tools in the present group of 100 MPD patients revealing also JAK2 mutation negative ET and PV patients displaying sole spontaneous CFU-Meg or BFU-E growth.
Two additional SNPs, rs2736100 (TERT) and rs9376092 (HBS1L/MYB), achieve genome-wide significance when including JAK2(V617F)-positive cases. rs9376092 has a stronger effect in JAK2(V617F)-negative cases with CALR and/or MPL mutations (Breslow-Day P=4.5 × 10(-7)), whereas in JAK2(V617F)-positive cases rs9376092 associates with essential thrombocythemia (ET) rather than polycythemia vera (allelic χ(2) P=7.3 × 10(-7)).
Finally, a significant correlation between JAK2V617F mutational status and hematocrit (Ht), white blood cell and platelet counts in PV patients, and Ht values in ET cases, was observed by AS-PCR.
Two CML patients who subsequently developed features of essential thrombocythemia with JAK2-V617F mutation while in complete cytogenetic remission after treatment with imatinib mesylate.
Given the distinct mortality and morbidity associated with ET, PV, and MF, the use of JAK2 inhibitors appears reasonable for patients with MF as well as for those with ET or PV who have become resistant or intolerant to hydroxyurea.
We conclude that JAK2 haplotype 46/1 confers susceptibility to developing ET independent of VF mutational status and does not seem to further affect the clinical phenotype or prognosis.
We studied 111 patients with ET; 39% were JAK2 mutant positive, and clone size (percentage mutant JAK2) was concordant with XCIP when constitutive T-cell patterns were taken into account.
Compared to JAK2-mutated ET patients, CALR-mutated ET patients were younger, showed lower WBC counts, lower hemoglobin levels, higher platelet counts, and fewer thrombotic events.
The JAK2V617F mutation is a frequent genetic event in the three classical Philadelphia-chromosome negative chronic myeloproliferative disorders (Ph(neg.)-CMPD), polycythemia vera (PV), essential thrombocythemia (ET) and idiopathic myelofibrosis (IMF).
Although these disorders were recognized as clonal hematopoietic stem cell disorders more than 3 decades ago, little was known about the genetic basis for these disorders until 2005 when a single recurrent mutation in the JAK2 tyrosine kinase (JAK2V617F) was identified in >90% of patients with PV and in a significant proportion of patients with ET and PMF.
We confirmed the coagulation activation in ET and PV patients but found no differences in levels of coagulation activation markers in relation to JAK2-V617F mutational status.
Signal transducers and activators of transcription 3 (STAT3) analysis of a small group of ET patients shows that in about half of the patients, there is STAT3 hyperactivation independently of JAK2 mutations, suggesting that the hyperactivation of STAT3 by JAK2 mutations or promoter activation may be a critical step in development of ET.
The JAK2 c.1849G>T (p.V617F) mutation leads to constitutive activation of Janus kinase (JAK)2 and contributes to dysregulated JAK signaling in myelofibrosis (MF), polycythemia vera (PV), and essential thrombocythemia (ET).
JAK2 is mutated (V617F) in more than 90 % of patients with polycythemia vera (PV) and approximately 60 % of patients with essential thrombocythemia (ET) or primary myelofibrosis (PMF).