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JAK2 V617F Mutation (jak2 + v617f_mutation)

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Medical Sciences	100%

Selected Abstracts

JAK2 V617F Mutation is uncommon in chronic myelomonocytic leukaemia

BRITISH JOURNAL OF HAEMATOLOGY, Issue 6 2005
M. F. Johan
No abstract is available for this article. [source]

Idiopathic myelofibrosis: pathogenesis to treatment

HEMATOLOGICAL ONCOLOGY, Issue 2 2006
John T Reilly
Abstract Idiopathic myelofibrosis (IMF) is the least common of the chronic myeloproliferative disorders and carries the worst prognosis with a median survival of 4 years. It is a clonal haematopoietic stem-cell disorder and, although the pathogenesis remains unclear, approximately 50% of cases are known to possess an activating JAK2 V617F mutation. In contrast, the characteristic stromal proliferation is a reactive, or secondary, event that results from the aberrant release of a variety of growth factors from megakaryocytes and monocytes. Treatment for most cases is supportive, although androgens, recombinant erythropoietin, steroids and thalidomide are effective modalities for the amelioration of anaemia. Myelosuppression, splenectomy and irradiation are valuable therapeutic modalities for specific clinical situations. Prognostic scores are available to aid the identification of cases for whom bone marrow transplantation should be considered. Recently, the use of reduced intensity conditioning has resulted in prolonged survival and lower transplant-related mortality. This review summarises the recent advances in the disease's pathogenesis and discusses the role of the various therapeutic options. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Incidence of the JAK2 V617F mutation among patients with splanchnic or cerebral venous thrombosis and without overt chronic myeloproliferative disorders

JOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 4 2007
V. DE STEFANO
Summary., Background:, Thrombosis of splanchnic or cerebral veins is a typical manifestation of polycythemia vera (PV) or essential thrombocythemia (ET). The recently identified Janus kinase 2 (JAK2) V617F somatic mutation is closely related to chronic myeloproliferative disorders (CMD). Objective:, To assess the incidence of the JAK2 V617F mutation among patients with splanchnic or cerebral venous thrombosis with or without overt CMD. Patients and methods:, We searched for the mutation in 139 adult patients (> 18 years old) with thrombosis of hepatic veins (HVT, n = 15), or extrahepatic portal vein (PVT) and/or mesenteric vein (MVT) (n = 79), or cerebral veins (CVT, n = 45). Only 19 patients fulfilled criteria for diagnosis of PV (n = 8) or ET (n = 11) at the time of thrombosis: four had HVT, 11 PVT and/or MVT, and four CVT. Results:, The JAK2 V617F mutation was found in 94.7% [95% CI 75.3,99.0] of the patients with overt CMD at the time of thrombosis, in 21.5% (95% CI 13.8,31.7) of the patients with abdominal venous thrombosis and without overt CMD, and in 4.8% (95% CI 1.3,16.1) of the patients with CVT and without overt CMD. Among the patients without overt CMD or thrombophilia and with unprovoked thrombosis, 29.4% (95% CI 16.8,46.1) with splanchnic venous thrombosis and 42.8% (95% CI 24.4,63.4) with PVT had the JAK2 V617F mutation. Conclusions:, A substantial proportion of patients with splanchnic venous thrombosis and a small, but significant, number of patients with CVT can be recognized as carriers of the JAK2 V617F mutation in the absence of overt signs of CMD. The clinical significance of such findings deserves further investigation. [source]

Outcome of 122 pregnancies in essential thrombocythemia patients: A report from the Italian registry

AMERICAN JOURNAL OF HEMATOLOGY, Issue 10 2009
Lorella Melillo
Pregnancy is a high-risk event in women with essential thrombocythemia (ET). This observational study evaluated pregnancy outcome in ET patients focusing on the potential impact of aspirin (ASA) or interferon alpha (IFN) treatment during pregnancy. We retrospectively analyzed 122 pregnancies in 92 women consecutively observed in the last 10 years in 17 centers of the Italian thrombocythemia registry (RIT). The live birth rate was 75.4% (92/122 pregnancies). The risk of spontaneous abortion was 2.5-fold higher than in the control population (P < 0.01). ASA did not affect the live birth rate (71/93, 76.3% vs. 21/29, 72.4%, P = 0.67). However, IFN treatment during pregnancy was associated with a better outcome than was management without IFN (live births 19/20, 95% vs. 73/102, 71.6%, P = 0.025), and this finding was supported by multivariate analysis (OR: 0.10; 95% CI: 0.013,0.846, P = 0.034). The JAK2 V617F mutation was associated with a poorer outcome (fetal losses JAK2 V617F positive 9/25, 36% vs. wild type 2/24, 8.3%, P = 0.037), and this association was still significant after multivariate analysis (OR: 6.19; 95% CI: 1.17,32.61; P = 0.038). No outcome concordance between first and second pregnancies was found (P = 0.30). Maternal complications occurred in 8% of cases. In this retrospective study, in consecutively observed pregnant ET patients, IFN treatment was associated with a higher live birth rate, while ASA treatment was not. In addition, the JAK2 V617F mutation was confirmed to be an adverse prognostic factor. Am. J. Hematol. 2009. © 2009 Wiley-Liss, Inc. [source]

Phospho-STAT5 and phospho-Akt expression in chronic myeloproliferative neoplasms

BRITISH JOURNAL OF HAEMATOLOGY, Issue 4 2009
Lizz F. Grimwade
Summary The majority of Myeloproliferative Neoplasms (MPNs) are characterised by mutations in genes encoding molecules or receptors involved in cell signalling, the most common being the JAK2 V617F mutation. This mutation leads to ligand-independent activation of downstream signalling pathways by constitutive phosphorylation. The signalling pathways affected include the Janus kinase-signal transducers and activators of transcription (JAK-STAT) and phosphotidylinositide-3 kinase (PI3K) pathways, which regulate cell survival and apoptosis respectively. Monoclonal antibodies to phospho-STAT5 and phospho-Akt were generated and assessed by immunocytochemistry on bone marrow biopsies of MPN patients with JAK2 V617F, JAK2 exon 12, MPL exon 10 and KIT D816V mutations. JAK2 V617F mutation was associated with significantly increased levels of phosphorylated STAT5 and Akt in haemopoietic cells, most marked in megakaryocytes. In contrast, JAK2 exon 12 and MPL exon 10 mutations did not affect the level of phosphorylation. In systemic mastocytosis with KIT D618V mutation there was significantly increased expression of phosphorylated STAT5 and Akt in neoplastic mast cells although there was no change in the expression in other haemopoietic cells. JAK2 V617F is associated with upregulated phosphorylation of STAT5 and Akt in megakaryocytes, and to a lesser extent in other haemopoietic cells. Immunocytochemistry of bone marrow trephines for these phospho-proteins can be used as a supplementary diagnostic test with a high negative predictive value. [source]

Prevalence of the JAK2 V617F mutation in patients with unprovoked venous thromboembolism of common sites and without overt myeloproliferative neoplasms

BRITISH JOURNAL OF HAEMATOLOGY, Issue 6 2009
Tommaso Za
No abstract is available for this article. [source]

The JAK2 V617F mutation involves B- and T-lymphocyte lineages in a subgroup of patients with Philadelphia-chromosome negative chronic myeloproliferative disorders

BRITISH JOURNAL OF HAEMATOLOGY, Issue 5 2007
Thomas Stauffer Larsen
Summary The JAK2 V617F mutation is a frequent genetic event in the three classical Philadelphia-chromosome negative chronic myeloproliferative disorders (Phneg. -CMPD), polycythemia vera (PV), essential thrombocythemia (ET) and idiopathic myelofibrosis (IMF). Its occurrence varies in frequency in regards to phenotype. The mutation is found in the majority of patients with PV and about half of the patients with ET and IMF. These diseases are clonal stem cell disorders arising in an early stem cell progenitor. The level in the stem cell hierarchy on which the initiating genetic events and the JAK2 V617F mutation occurs is not known. The mutation has so far been detected in all cells of the myeloid lineage, whereas the potential clonal involvement of the lymphoid lineage is controversial. In this study, we detected the JAK2 V617F mutation by real-time quantitative PCR (qPCR) in both B-lymphocytes and T-lymphocytes in a subgroup of patients with Phneg. -CMPDs. These results demonstrate the origin of the JAK2 V617F positive disorders in an early stem cell with both lymphoid and myeloid differentiation potential. [source]