Allelic Expression Imbalance of JAK2 V617F Mutant Contributes to Phenotypic Variation in BCR-ABL Negative Chronic Myeloproliferative Disorders.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 4651-4651
Author(s):  
Myung-Geun Shin ◽  
Hye-Ran Kim ◽  
Hyeoung-Joon Kim ◽  
Mi-Ji Kim ◽  
Hee-Nam Kim ◽  
...  
Keyword(s):  
Gene Expression ◽  
Genomic Dna ◽  
Mutant Allele ◽  
Jak2 V617f ◽  
Myeloproliferative Disorders ◽  
Allelic Expression ◽  
Jak2 V617f Mutation ◽  
Allelic Expression Imbalance ◽  
Mutation Status ◽  
V617f Mutation

Abstract Background: An acquired somatic mutation in the JAK2 gene (V617F) could present the primary causative lesion in BCR-ABL-negative chronic myeloproliferative disorders (CMPD). However, some of the clinical and genetic data implied that the pathophysiological role of JAK2 V617F mutation in the CMPD would be more complex. Quantitative assessment of JAK2 V617F mutation has shown substantial heterogeneity in the genomic DNA. Recently, it has been reported that allelic variation in gene expression is common in the human genome. To test the hypothesis that JAK2 V617F mutant allele could be increased in cDNA, we examined JAK2 V617F mutation status in the genomic DNA and cDNA from a total of 78 patients with BCR-ABL-negative CMPD. Patients and Methods: Enrolled patients with BCR-ABL-negative CMPD in this study comprised 42 cases of essential thrombocythemia (ET), 26 polycythemia vera (PV), 7 idiopathic myelofibrosis (MF) and 3 unclassifiable (UC) CMPD. A 364-bp PCR product containing JAK2 V617F mutation was bidirectionally sequenced from total BM cells. A quantitative real time PCR-based allelic discrimination assay and pyrosequencing (Pyrosequencer PSQ96) were developed for quantitative analysis of JAK2 V617F mutation status. Homozygous JAK2 V617F mutation was defined if the mutant peak was more than 50% of total peak area. Results: The proportion of mutant alleles ranged from 36% to 100% in real-time PCR and pyrosequencing analysis. Patients with MF had higher percentages of JAK2 mutant alleles than patients with ET (MF > PV > ET). The prevalence of homozygous V617F mutations was significantly higher in PV patients (73%) than in patients with ET (17%). Allelic expression imbalance of heterozygous JAK2 mutation was common in patients with PV and ET. Interestingly, allelic expression imbalance in patients with MF was not remarkably impaired, but preferential expression of JAK2 mutant allele showed threefold increase from the cDNA compared with the genomic DNA from patients with PV and ET. Conclusion: Allelic imbalance in the gene expression of JAK2 V617F mutant could provide the underlying mechanisms to elucidate phenotypic variation in BCR-ABL negative CMPD.

Relation between JAK2 (V617F) mutation status, granulocyte activation, and constitutive mobilization of CD34+ cells into peripheral blood in myeloproliferative disorders

Blood ◽  
2006 ◽  
Vol 107 (9) ◽  
pp. 3676-3682 ◽  
Author(s):  
Francesco Passamonti ◽  
Elisa Rumi ◽  
Daniela Pietra ◽  
Matteo G. Della Porta ◽  
Emanuela Boveri ◽  
...  
Keyword(s):  
Polycythemia Vera ◽  
Gene Dosage ◽  
Jak2 V617f ◽  
Myeloproliferative Disorders ◽  
Jak2 V617f Mutation ◽  
Disease Category ◽  
Mutation Status ◽  
Cell Counts ◽  
Cd34 Cells ◽  
V617f Mutation

We studied the relationship between granulocyte JAK2 (V617F) mutation status, circulating CD34+ cells, and granulocyte activation in myeloproliferative disorders. Quantitative allele-specific polymerase chain reaction (PCR) showed significant differences between various disorders with respect to either the proportion of positive patients (53%-100%) or that of mutant alleles, which overall ranged from 1% to 100%. In polycythemia vera, JAK2 (V617F) was detected in 23 of 25 subjects at diagnosis and in 16 of 16 patients whose disease had evolved into myelofibrosis; median percentages of mutant alleles in these subgroups were significantly different (32% versus 95%, P < .001). Circulating CD34+ cell counts were variably elevated and associated with disease category and JAK2 (V617F) mutation status. Most patients had granulocyte activation patterns similar to those induced by administration of granulocyte colony-stimulating factor. A JAK2 (V617F) gene dosage effect on both CD34+ cell counts and granulocyte activation was clearly demonstrated in polycythemia vera, where abnormal patterns were mainly found in patients carrying more than 50% mutant alleles. These observations suggest that JAK2 (V617F) may constitutively activate granulocytes and by this means mobilize CD34+ cells. This exemplifies a novel paradigm in which a somatic gain-of-function mutation is initially responsible for clonal expansion of hematopoietic cells and later for their abnormal trafficking via an activated cell progeny.

Correlation of JAK2 V617F Mutation Status and Cytogenetic Findings in Myeloproliferative Disorders.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 3633-3633
Author(s):  
Guoxian Sun ◽  
Frank Buccini ◽  
Elizabeth Fuentes ◽  
James Weisberger
Keyword(s):  
Jak2 V617f ◽  
Myeloproliferative Disorders ◽  
Chromosome Abnormalities ◽  
Jak2 V617f Mutation ◽  
Homozygous Mutation ◽  
Jak2 Mutation ◽  
Mutation Status ◽  
Trisomy 9 ◽  
V617f Mutation ◽  
Trisomy 9P

Abstract Detection of JAK2 V617F mutation is quickly becoming a front-line screening test for suspected myeloproliferative disorders (MPDs), as the mutation shows high frequency and specificity in non-CML MPDs, PV, ET or CIMF. Routine cytogenetics can detect chromosome abnormalities in approximately 20% of MPDs and is very helpful in establishing or confirming the presence of aberrant clonality, although chromosome changes are often numerical gains and losses, deemed non-specific. To see if there is correlation between JAK2 mutation and karyotypes, we studied 57 consecutive patients with clinically and morphologically confirmed diagnosis of non-CML MPDs. JAK2 V617F mutation performed using allele-specific PCR (sensitive to 10% using pyrosequencing) was found in 72% of patients (41/57), whereas clonal chromosome abnormalities were observed in 15.8% (9/57). There was no correlation between JAK2 mutational status and karyotypes. In 41 patients positive for the JAK2 mutation, 6 were cytogenetically abnormal and 35 normal. In 16 patients negative for the mutation, 3 showed abnormal karyotypes and 13 had normal karyotypes (X2 test, p>0.5). Among 6 patients with both JAK2 mutation and an abnormal karyotype, JAK2 mutation was seen in >50% of each sample in 4 patients, consistent with a homozygous mutation. Interestingly, in two cases, one with PV and trisomy 9 and another with MPD unclassifiable and trisomy 9p resulting from an unbalanced translocation between chromosomes 9p and 13, JAK2 mutation was present in >65% of each sample. Trisomy 9 and trisomy 9p are common abnormalities in MPDs, particularly in PV, seen in over 20% of cytogenetically abnormal cases. JAK2 gene is located on 9p24. Mitotic recombination is considered the most likely cause of loss of heterozygosity (LOH) and thus mutant homozygosity which is undetectable at the cytogenetic level. However, in cases with trisomy 9 or 9p, the JAK2 allele genotypes may be G/T/T and/or T/T/T as well as the usual G/T and/or T/T. Our observations suggest that trisomy 9 or 9p should be taken into consideration when interpreting JAK2 mutation status and that further molecular studies are needed to delineate the implication of trisomy 9 or 9p in potential mutant allele selective advantage and clonal evolution in JAK2 mutation positive MPDs.

scholarly journals Allelic Expression Imbalance of JAK2 V617F Mutation in BCR-ABL Negative Myeloproliferative Neoplasms

PLoS ONE ◽  
2013 ◽  
Vol 8 (1) ◽  
pp. e52518 ◽  
Author(s):  
Hye-Ran Kim ◽  
Hyun-Jung Choi ◽  
Yeo-Kyeoung Kim ◽  
Hyeoung-Joon Kim ◽  
Jong-Hee Shin ◽  
...  
Keyword(s):  
Myeloproliferative Neoplasms ◽  
Jak2 V617f ◽  
Allelic Expression ◽  
Jak2 V617f Mutation ◽  
Allelic Expression Imbalance ◽  
V617f Mutation

MD.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 4863-4863
Author(s):  
Zartash Gul ◽  
Naomi Galili ◽  
Nishant Tageja ◽  
Azra Raza
Keyword(s):  
Genomic Dna ◽  
Conflicts Of Interest ◽  
Phenotypic Expression ◽  
Gene Sequencing ◽  
Jak2 V617f ◽  
Myeloproliferative Disorders ◽  
Jak2 V617f Mutation ◽  
Jak2 Mutation ◽  
V617f Mutation

Abstract Abstract 4863 THE SECONDARY TRANSFORMATION OF MDS INTO MYELOFIBROSIS IS INDEPENDENT OF THE JAK2 MUTATION Introduction The exact significance of the JAK2 V617F mutation in MDS is unclear. It has previously been suggested that MF could be associated with MDS as one phenotype of myeloproliferative disorders. Ohyashiki et al in 2005 showed that two of six patients with MDS terminating in MF had the mutation at the time of MF, while no MDS patient without MF had the JAK2 V617F mutation, suggesting that MDS patients with the JAK2 V617F mutation may be responsible for secondary MF in MDS patients. We conducted the following experiments to further probe the role of JAK2 mutation in the pathology of MDS with myelofibrosis at our institution. Methods DNA samples of 8 patients in our institution who had MDS with subsequent myelofibrosis were isolated. Genomic DNA isolated using DN easy tissue kit(Qiagen) was amplified by PCR. After confirmation of DNA presence on 1 % agarose gel and purification using QIA quick PCR purification kit (Qiagen), gene sequencing was done. This sequencing was then analyzed for G to T mutation V617F in JAK2. Results We found no evidence of the JAK2 mutation in any of the eight samples. Discussion Given the fact that nearly half the patients with myelofibrosis carry the JAK2 V617F mutation, the possibility of an association between those patients who have myelodysplasia and subsequent myelofibrosis needs to researched. Our cohort which consisted of 8 patients showed no evidence for any such correlation. This evidence confirms the presence of different pathophysiological mechanisms for phenotypic expression of MDS and primary MF and also leads us to suggest that the expression of JAK2 is not the driving mutation in the pathogenesis of MDS progression to myelofibrosis. Disclosures No relevant conflicts of interest to declare.

Prevalence of the JAK2-V617F mutation in Taiwanese patients with chronic myeloproliferative disorders

2008 ◽  
Vol 38 (6a) ◽  
pp. 422-426 ◽  
Author(s):  
C.-H. Lieu ◽  
H.-S. Wu ◽  
Y.-C. Hon ◽  
W.-H. Tsai ◽  
C.-F. Yang ◽  
...  
Keyword(s):  
Jak2 V617f ◽  
Myeloproliferative Disorders ◽  
Jak2 V617f Mutation ◽  
Chronic Myeloproliferative Disorders ◽  
V617f Mutation

Evaluation of the JAK2 V617F gene mutation in myeloproliferative neoplasms cases: a one-center study from Eastern Anatolia

2019 ◽  
Vol 44 (4) ◽  
pp. 492-498
Author(s):  
Gonca Gulbay ◽  
Elif Yesilada ◽  
Mehmet Ali Erkurt ◽  
Harika Gozukara Bag ◽  
Irfan Kuku ◽  
...  
Keyword(s):  
Blood Cell ◽  
Essential Thrombocythemia ◽  
Myeloproliferative Neoplasms ◽  
Hematological Parameters ◽  
Jak2 V617f ◽  
Primary Myelofibrosis ◽  
Myeloproliferative Disorders ◽  
Jak2 V617f Mutation ◽  
V617f Mutation ◽  
The Difference

AbstractObjectiveDetection ofJAK2V617F in myeloproliferative neoplasms (MPNs) is very important in both diagnosis and disease progression. In our study, we investigated the frequency ofJAK2V617F mutation in patients with myeloproliferative disorders.MethodsWe retrospectively reviewed the records of 720 patients (174 females and 546 males) who were tested for JAK2 V617F mutation from January 2007 to December 2017.ResultsIn our patients were determined 22.6%JAK2V617F mutation. 33.3% in women, 19.2% in men have been positive forJAK2V617F mutation. In our studyJAK2V617F present in 48.6% of essential thrombocythemia, 80.5% of polycythemia rubra vera (PV), 47.5% of primary myelofibrosis, 10% of MPNs, unclassifiable, 0.8% of others. We also investigated the difference in hematological parameters [white blood cell, hemoglobin (Hb), hematocrit (HCT), red blood cell distribution widths (RDW) and platelets count (PLT)] betweenJAK2V617F positive andJAK2V617F negative patients.ConclusionsInvestigation of the JAK2 V617F mutation is very important in cases of MPNs. In our study JAK2 V617F mutation was higher in PV, essential thrombocythemia, and primary myelofibrosis patients. However, there were significant differences in Hb, HCT, RDW and PLT levels in mutation-positive patients.

Relationship between JAK2 V617F Mutation Status, Granulocyte CD177 mRNA Expression and CD177 Soluble Protein Level in Patients with Polycythemia Vera.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 2578-2578
Author(s):  
Daniela Pietra ◽  
Alessandra Balduini ◽  
Carmela Marseglia ◽  
Matteo G. Della Porta ◽  
Luca Malcovati ◽  
...  
Keyword(s):  
Mrna Expression ◽  
Polycythemia Vera ◽  
Protein Level ◽  
Mononuclear Cells ◽  
Jak2 V617f ◽  
Myeloproliferative Disorders ◽  
Jak2 V617f Mutation ◽  
Serum Samples ◽  
Close Relationship ◽  
V617f Mutation

Abstract A unique gain-of-function mutation of the Janus kinase 2 (JAK2) gene has been recently described in patients with polycythemia vera (PV), essential thrombocythemia and chronic idiopathic myelofibrosis [N Engl J Med. 2005 Apr 28;352(17):1779–90]. Although the currently available data clearly demonstrate that the JAK2 V617F mutation participates in the pathogenesis of myeloproliferative disorders, the mutation’s precise place in the hierarchical order of pathogenetic events remains to be established. We have recently reported that altered gene expression in myeloproliferative disorders correlates with activation of signaling by the V617F mutation of JAK2 (Blood. 2005 Aug 4; Epub ahead of print). Granulocyte CD177 (PRV1) mRNA overexpression has been initially reported as a potential marker of PV but later shown by us to rather be a marker of neutrophil activation [Br J Haematol. 2004 Sep;126(5):650–6]. In this study, we analyzed the relationship between JAK2 V617F mutation status, granulocyte CD177 mRNA expression and CD177 soluble protein level in 72 patients with PV. We also investigated the ontogeny of CD177 expression by hematopoietic cells with the aim of defining the stage of mRNA expression during myeloid, erythroid and megakaryocytic cell differentiation. Finally we studied the effect of soluble CD177 protein on hematopoietic cell proliferation and differentiation. Granulocyte CD177 mRNA expression and percentage of JAK2 V617F alleles were evaluated by quantitative Real Time PCR (qRT-PCR), while serum CD177 protein level was measured by a flow cytometry-based competitive antibody-binding assay. Liquid cultures were performed by culturing peripheral blood mononuclear cells obtained from healthy individuals and PV patients in the presence of high CD177-expressing, low CD177-expressing or CD177-depleted sera. After 12 days of culture, cells were collected, counted and evaluated for colony growth, and for flow cytometry analysis of myeloid, erythroid, megakaryocytic and CD34-positive cell subpopulations. qRT-PCR studies showed a close relationship between CD177 mRNA level and percentage of JAK2 V617F alleles (r=0.412, P&lt;0.001). CD177 mRNA expression was almost undetectable in cell populations other than granulocytes. Studies of CFU-GM growth and differentiation indicated that CD177 mRNA expression is a late event restricted to the neutrophil stage of differentiation. Analysis of serum samples showed variable values for mean fluorescence intensity (MFI), indicating variable levels of the soluble CD177 protein in the patients studied. A very close relationship was found between granulocyte CD177 mRNA expression and soluble CD177 protein level (r=0.56, P=0.02). Incubation of mononuclear cells with serum samples showing high levels of soluble CD177 protein resulted in increased numbers of CD34-positive cells (P&lt;0.02) and of erythroid progenitors (P&lt;0.03). This effect was not detectable when low CD177-expressing or CD177-depleted sera were employed. These observations clearly indicate that the JAK2 V617F mutation is associated with enhanced granulocyte CD177 mRNA expression, and that this latter results in high levels of soluble CD177 protein. These elevated levels might contribute to the increased red cell production that characterizes polycythemia vera.

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