UMLS:C0032463 - FACTA Search

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Query: UMLS:C0032463 (polycythemia vera)
3,374 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Following the introduction of the WHO classification of chronic myeloproliferative disorders (MPDs), after approximately 5 years, a critical reappraisal appears to be warranted. Retrospective clinico-pathological evaluations conducted in the meantime, as well as the detection of new biomarkers, may aid in testing the validity of these new criteria. Based on a large series of patients with chronic myeloid leukemia (CML), an analysis of bone marrow (BM) features and risk classifications revealed that the fiber content exerted a most important and independent impact on prognosis. This finding was also supported in a prospective randomized study and therefore myelofibrosis should be included in any staging system in CML related to survival. Moreover, it is important to emphasize the dynamics of the disease process in MPDs, especially in polycythemia vera (PV) and chronic idiopathic myelofibrosis (CIMF). Latent-stage PV is difficult to recognize when adhering to the proposed limits for hemoglobin (or red cell mass) without regarding the erythropoietin (EPO) level, endogenous erythroid colonies (EECs) or BM histopathology. Initial PV may firstly present with complications and, when accompanied by a high platelet count, mimics essential thrombocythemia (ET). Consequently, BM morphology and EPO level should be entered as major diagnostic criteria for PV. To document more accurately the progress of disease, a simplified scoring system concerning myelofibrosis has to be included in the histological description of CIMF. The diagnostic guidelines of BM features in ET should be improved because, usually, there is neither a significant proliferation nor left-shifting of the granulo- and erythropoiesis detectable and no relevant increase in reticulin. A comparison of clinical data and BM morphology reveals that biomarkers (EPO, EECs, PRV-1, JAK2) show an overlapping pattern of positivity between the different subtypes of MPDs.
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PMID:A critical reappraisal of the WHO classification of the chronic myeloproliferative disorders. 1639 60

The polycythemia rubra vera 1 gene (PRV-1), a member of the urokinase-type plasminogen activator receptor superfamily, is overexpressed in granulocytes isolated from the peripheral blood of patients with polycythemia vera (PV) and essential thrombocythemia (ET). PRV-1 overexpression is the first reliable molecular marker of these myeloproliferative disorders, and its detection allows us to discriminate PV and ET from secondary erythrocytosis and thrombocytosis. PRV-1 overexpression can be investigated by several techniques, including Northern analysis, reverse-transcription (RT)-polymerase chain reaction (PCR), and real-time PCR. Among these, RT-PCR is the most rapid, reliable, and feasible method for the detection of PRV-1 overexpression in highly purified peripheral blood granulocytes.
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PMID:Overexpression of PRV-1 gene in polycythemia rubra vera and essential thrombocythemia. 1650 91

JAK2(V617F)an acquired mutation of JAK2, is present in a majority of patients with polycythemia vera and to a lesser extent among patients with the other myeloproliferative disorders. We analyzed the effect of JAK2(V617F) on the expression of polycythemia rubra vera 1(PRV-1), using an in vitro model. Compared to wild-type JAK2, the presence of JAK2(V617F) increased both PRV-1 protein and mRNA levels in murine myeloid cells. A JAK2 inhibitor eliminated the V617F-induced increase in PRV-1 expression.
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PMID:The effect of the JAK2 V617F mutation on PRV-1 expression. 1650 46

Microvascular disturbances in essential thrombocythemia (ET) and polycythemia vera (PV), including erythromelalgia, and atypical and typical transient cerebral, ocular, and coronary ischemic attacks, are caused by platelet-mediated transient and occlusive thrombosis in the end-arterial circulation. ET patients with microvascular disturbances have shortened platelet survival, increased beta-thromboglobulin (beta-TG), platelet factor 4 (PF4), and thrombomodulin (TM) levels, and increased urinary thromboxane B2 (TXB2) excretion, indicating platelet-mediated thrombotic processes. Inhibition of platelet cyclooxygenase-1 by aspirin is followed by relief of microvascular disturbances; correction of shortened platelet survival; correction of increased plasma beta-TG, PF4, and TM levels; and correction of increased TXB2 excretion to normal. In PV associated with thrombocythemia, increased hematocrit and whole blood viscosity aggravate the platelet-mediated microvascular syndrome of thrombocythemia to produce major arterial and venous thrombotic complications. Correction of hematocrit to normal by phlebotomy will reduce the major arterial and venous thrombotic complications, but fails to prevent the platelet-mediated microvascular circulation disturbances in PV patients because thrombocythemia persists. Complete relief and prevention of microvascular and major thrombosis in ET and PV patients, in addition to phlebotomy, are obtained by treatment with aspirin and not with coumarin. The discovery of JAK2 V617F gain of function mutation in patients with myeloproliferative disorders (MPDs) expands our insights into the molecular etiology and biological features of ET, PV, and chronic idiopathic myelofibrosis (CIMF). The current concept is that heterozygous JAK2 V617F mutation with increased kinase activity is enough for megakaryocyte proliferation and increased hypersensitive platelets with no or slightly increased erythropoiesis in ET and in early PV mimicking ET. Homozygous JAK2 mutation with pronounced kinase activity is associated with trilinear megakaryocyte, erythroid, and granulocytic myeloproliferation, myeloid metaplasia, and secondary myelofibrosis (MF), with the most frequent clinical picture of classical PV complicated by major thrombosis in addition to the platelet-mediated microvascular thrombotic syndrome of thrombocythemia. The positive predictive value of a JAK2 V617F polymerase chain reaction test for the diagnosis of MPDs is high (near to 100%), but only half of ET and MF (sensitivity 50%) and the majority of PV (sensitivity 85 to 97%) are JAK2 V617F positive. Bone marrow histopathology, when used in combination with specific markers such as serum erythropoietin, PRV-1, endogenous erythroid colony formation, peripheral blood parameters and red cell mass, has a high sensitivity and specificity (near 100%) to detect the early and overt stages of the MPDs and to differentiate between ET, PV, and CIMF in both JAK2 V617F-positive and -negative MPDs.
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PMID:Clinical and laboratory features, pathobiology of platelet-mediated thrombosis and bleeding complications, and the molecular etiology of essential thrombocythemia and polycythemia vera: therapeutic implications. 1667 74

No specific diagnostic markers have been described in essential thrombocythemia (ET). PRV-1 (polycythemia rubra vera-1), TPO (thrombopoietin), and c-MPL (myeloproliferative leukemia virus oncogene) genes are candidate ET molecular markers because of their implication in the pathogenesis of ET. We have studied the status of PRV-1, TPO, and c-MPL genes in 30 ET patients by a fluorescence in situ hybridization (FISH) technique using three noncommercial, locus-specific probes for PRV-1 (BAC RP11-160A19, located at 19q13.2), TPO (BAC RP11-45NP16, located at 3q27), and c-MPL (BAC RP11-297L5, located at 1p34). FISH study showed no PRV-1, TPO, and c-MPL cytogenetic abnormalities in any of the analyzed cases. Our results suggest a lack of structural and numerical rearrangements (deletions, translocations, or amplifications) of PRV-1, TPO, and c-MPL genes in ET patients.
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PMID:Detection of abnormalities of PRV-1, TPO, and c-MPL genes detected by fluorescence in situ hybridization in essential thrombocythemia. 1668 84

The clinical criteria according to the Polycythemia Vera Study Group (PVSG) do not distinguish between essential thrombocythemia (ET), thrombocythemia associated with early-stage polycythemia vera (PV) and prefibrotic chronic idiopathic myelofibrosis (CIMF). The criteria only classify the advanced stage of PV with increased red cell mass. The classification of myeloproliferative disorders (MPDs), proposed by the World Health Organization (WHO) in 2001, is a compromise of the clinical PVSG and WHO bone marrow criteria, and excludes early stages of ET and PV. The updated European clinical and pathological criteria combine the WHO bone marrow criteria with established and new clinical, laboratory, biological, and molecular MPD markers. This allows clinicians and pathologists to diagnose early-stage MPD and to differentiate ET, PV, and prefibrotic chronic idiopathic myelofibrosis (CIMF). Depending on laboratory tests and diagnostic criteria used, the population of the MPD patients defined as ET, PV, and CIMF are heterogeneous at the clinical, laboratory, and biological and pathological levels. The recent discovery of the JAK2 V617F mutation, which is the cause of a distinct trilinear MPD in its manifold clinical manifestations during long-term follow-up, increases the specificity of a positive JAK2 V617F polymerase chain reaction (PCR) test for the diagnosis of MPD (near 100%), but only half of the ET and CIMF patients according to the PVSG (sensitivity 50%) and the majority of PV patients (sensitivity 95%) are JAK2 V617F positive. A comparison of the laboratory features of JAK2 V617-positive and JAK2 wild-type ET patients clearly showed that JAK2 V617-positive ET is characterized by higher values for hemoglobin, hematocrit, and neutrophil counts; lower values for serum erythropoietin (EPO) levels, serum ferritin, and mean corpuscular volume; and by increased cellularity of the bone marrow in biopsy material. This indicates that JAK2 V617-positive ET patients, diagnosed according to the PVSG criteria, represent a "forme fruste of PV" consistent with early PV mimicking ET (JAK2 V617F trilinear MPD). In contrast, the JAK2 wild-type ET patients had significantly higher platelet counts and usually had a clinical picture of ET with normal serum EPO levels, PRV-1 expression, and leukocyte alkaline phosphatase score, and a typical WHO ET bone marrow picture. The clinical and pathological data on JAK2 V617F-positive MPD patients suggest that the JAK2 V617F mutation defines one disease entity with several sequential steps of ET, PV, and secondary myelofibrosis during long-term follow-up, and that the wild-type JAK2 MPDs may represent another distinct entity with a related but different molecular etiology. MPD-specific markers such as serum EPO, endogenous erythroid colony formation (EEC), and JAK2 V617F have high specificities, but the sensitivities are not high enough to detect the early stages of the MPDs, ET, PV, and prefibrotic CIMF. Bone marrow histopathology in addition to clinical, laboratory, biological, and molecular markers, including the JAK2 V617 PCR test, serum EPO, PRV-1, EEC, LAP score, peripheral blood parameters, and spleen size on echogram will detect the early stages of MPD and allows diagnostic differentiation of the three primary MPDs (ET, PV, and CIMF) in both JAK2 V617F-positive and JAK2 wild-type MPD patients.
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PMID:The 2001 World Health Organization and updated European clinical and pathological criteria for the diagnosis, classification, and staging of the Philadelphia chromosome-negative chronic myeloproliferative disorders. 1681 Jun 9

The clinical criteria for the diagnosis of essential thrombocythemia (ET) according to the polycythemia vera study group (PVSG) do not distinguish between ET and thrombocythemia associated with early stage PV and prefibrotic chronic idiopathic myelofibrosis (CIMF). The clinical criteria of the PVSG for the diagnosis of polycythemia vera (PV) only detects advanced stage of PV with increased red cell mass. The bone marrow criteria of the World Health Organization (WHO) are defined by pathologists to explicitly define the pathological criteria for the diagnostic differentiation of ET, PV, and prefibrotic and fibrotic CIMF. As the clinical PVSG and the pathological WHO criteria show significant shortcomings, an updated set of European Clinical and Pathological (ECP) criteria combined with currently available biological and molecular markers are proposed to much better distinct true ET from early PV mimicking ET, to distinguish ET from thrombocythemia associated with prefibrotic CIMF, and to define the various clinical and pathological stages of PV and CIMF that has important therapeutic and prognostic implications. Comparing the finding of clustered giant abnormal megakaryocytes in a representative bone marrow as a diagnostic clue to MPD, the sensitivity for the diagnosis of MPD associated with splanchnic vein thrombosis was 63% for increased red cell mass, 52% for low serum EPO level, 72% for EEC, and 74% for splenomegaly indicating the superiority of bone marrow histopathology to detect masked early and overt MPD in this setting. The majority of PV and about half of the ET patients have spontaneous EEC, low serum EPO levels and PRV-1 over-expression and are JAK2 V617F positive. The positive predictive value for the diagnosis of PV of spontaneous growth of endogenous erythroid colonies (EEC) of peripheral blood (PB) and bone marrow (BM) cells is about 80-85% when either PB or BM EEC assays, and up to 94% when BM and PB EEC assays were performed. The diagnostic impact of low serum EPO levels (ELISA assay) in a large study of 186 patients below the normal range (<3.3 IU/l) had a sensitivity specificity and positive predictive value of 87%, 97% and 97.8%, respectively, for the diagnosis of PV. There is a significant overlap of serum EPO levels in PV versus control and controls versus SE. The specificity of a JAK2 V617F PCR test for the diagnosis of MPD is high (near 100%), but only half of ET and MF (50%) and the majority of PV (up to 97%) are JAK2 V617F positive. The use of biological markers including JAK2 V617 PCR test, serum EPO, PRV-1, EEC, leukocyte alkaline phosphatase score and peripheral blood parameters combined with bone marrow histopathology has a high sensitivity and specificity (almost 100%) to diagnose the early and overt stages of ET, PV and CIMF in JAK2 V617F positive and negative MPDs.
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PMID:Current diagnostic criteria for the chronic myeloproliferative disorders (MPD) essential thrombocythemia (ET), polycythemia vera (PV) and chronic idiopathic myelofibrosis (CIMF). 1691 93

Three consecutive polycythemia vera (PV) patients were analyzed before and during pegylated-interferon (rIFNalpha) treatment for the following markers: (1) granulocyte and CD34(+) cell clonality, (2) Jak2V617F expression, (3) PRV-1 mRNA overexpression, and (4) Epo-independent colony (EEC) growth. Before rIFNalpha therapy, all patients displayed clonal hematopoiesis, 100% Jak2V617F expression as well as PRV-1 overexpression, and EEC growth. After rIFNalpha treatment, all three patients demonstrated polyclonal hematopoiesis. Nonetheless, Jak2V617F expression, PRV-1 overexpression, and EEC-growth remained detectable, albeit at lower levels. We conclude that reemergence of polyclonal hematopoiesis after rIFNalpha treatment may be achieved in a substantial proportion of patients. However, this does not constitute elimination of the PV clone. These data demonstrate the usefulness of novel markers in monitoring minimal residual disease and caution against discontinuation of rIFNalpha treatment after hematologic remission. Long-term follow-up of large patient cohorts is required to determine whether rIFNalpha treatment can cause complete molecular remissions in PV.
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PMID:Biomarker analysis in polycythemia vera under interferon-alpha treatment: clonality, EEC, PRV-1, and JAK2 V617F. 1725 45

We report a novel TaqMan assay for JAK2 V617F that measures averaged copies per cell in absolute terms, as opposed to a ratio of mutant to wild-type alleles. Measurements were obtained by comparing the JAK2 V617F signal generated by the test samples to that generated by a set of external plasmid standards containing the sequence of interest. Specificity of the assay was demonstrated above 36 cycles of amplification, and endpoint titration experiments indicated sensitivity down to 0.05% clinical dilutions. The test measured linearly over a wide logarithmic range and exhibited good reproducibility. Combination of this assay with another TaqMan method for determining cell number allowed identification of 14 cases of myeloproliferative disease with greater than two copies per cell. Mutational frequency was 68% among polycythemia vera (n=44), 59% (n=37) among essential thrombocythemia and 46% (n=13) among idiopathic myelofibrosis. Levels of the mutation were significantly higher in polycythemia vera compared with essential thrombocythemia (P=0.0005) and correlated with the following jointly significant variables at diagnosis: PRV-1, hemoglobin, white cell count, neutrophil count, and red cell count, using multiple regression analyses (P=0.015). This method should be useful for assessing the relationship of gene dose to phenotype and possibly for monitoring therapy.
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PMID:Quantitative determination of JAK2 V617F by TaqMan: An absolute measure of averaged copies per cell that may be associated with the different types of myeloproliferative disorders. 1738 17

The aim of this study was to determine whether the burden of JAK2(V617F) allele correlated with major clinical outcomes in patients with polycythemia vera (PV). To this end, we determined JAK2 mutant allele levels in granulocytes of 173 PV patients at diagnosis. The mean (+/-s.d.) mutant allele burden was 52% (+/-29); 32 patients (18%) had greater than 75% mutant allele. The burden of JAK2(V617F) allele correlated with measurements of stimulated erythropoiesis (higher hematocrit, lower mean cell volume, serum ferritin and erythropoietin levels) and myelopoiesis (higher white cell count, neutrophil count and serum lactate dehydrogenase) and with markers of neutrophil activation (elevated leukocyte alkaline phosphatase and PRV-1 expression). As compared to those with less than 25% mutant allele, patients harboring greater than 75% JAK2(V617F) allele were at higher relative risk (RR) of presenting larger spleen (RR 4.7; P<0.001) or suffering from pruritus (RR 3.1; P<0.001). In these patients, the risk of requiring chemotherapy (RR 1.8; P=0.001) or developing major cardiovascular events (RR 7.1; P=0.003) during follow up were significantly increased. We conclude that a burden of JAK2(V617F) allele greater than 75% at diagnosis points to PV patients with high-risk disease.
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PMID:Prospective identification of high-risk polycythemia vera patients based on JAK2(V617F) allele burden. 1762 6

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