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.

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.

JAK2 (V617F) Mutation Status and Neutrophil Apoptotic Resistance in Myelofibrosis with Myeloid Metaplasia (MMM): Correlation and Potential Identification through Phosphorylation Status of STAT3.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 3503-3503
Author(s):  
Ruben A. Mesa ◽  
Ayalew Tefferi ◽  
Heather Powell ◽  
Terra Lasho ◽  
David Loegering ◽  
...  
Keyword(s):  
Jak2 V617f ◽  
Jak2 V617f Mutation ◽  
Neutrophil Apoptosis ◽  
Wild Type ◽  
Jak2 Mutation ◽  
Myeloid Metaplasia ◽  
Mutation Status ◽  
Stat3 Phosphorylation ◽  
V617f Mutation ◽  
Myelofibrosis With Myeloid Metaplasia

Abstract Background: We have previously described a resistance to the normal process of apoptosis in neutrophils of patients with myelofibrosis with myeloid metaplasia (MMM) (Blood2003;102:11). Most recently, an activating mutation of JAK2 (V617F) has been described in approximately half of the patients with MMM as well as in variable proportion of patients with other myeloproliferative disorders (MPD). In the current study, we investigated the correlation between JAK2 V617F mutation status and neutrophil apoptosis in MMM. Methods: Neutrophils were isolated by density centrifugation from patients with MMM, other MPDs, and normal controls and assessed for apoptosis at baseline and after 24 hours in culture (IMDM with 20% sterilized fetal calf serum to simulate spontaneous apoptosis). Apoptosis was quantified using three-color flow cytometry using CD45 (to confirm leukocyte presence), annexin V (AN) (marker of apoptosis; detects aberrant externalization of phosphatidylserine during apoptosis), and propidium iodide (PI) (marker of dead cells). Mutation analysis for JAK2 V617F was performed in DNA derived from the isolated neutrophils using genomic DNA amplified by PCR, or extracted from cytogenetic pellets in archived specimens. Apoptotic rates after 24 hours in culture were correlated between patients and controls for both JAK2 mutation status and clinical parameters. Immunoblotting was performed on a subset of patients for correlation of JAK2 mutation status and downstream phosphorylation of the JAK2 target, STAT3, which transcriptionally activates several antiapoptotic genes. Results: Spontaneous neutrophil apoptosis was significantly decreased in MMM patients (n=50; median % apoptotic cells at 41%) compared to both healthy volunteers (n=9; 66%) and patients with other MPD (n=11; 53%) (p=0.002). Resistance to apoptosis in MMM correlated with both anemia (p=0.01) and the presence of the JAK2 V617F mutation (p=0.01). Furthermore, the specific abnormality was more pronounced in patients with homozygous JAK2 V617F; median % apoptotic cells of 47% for patients with wild-type allele (n=22) vs. 39% for heterozygotes (n=23) vs. 22% for homozygotes (n=5; p=0.008). The JAK2 mutation status did not appear dependent on other peripheral blood or clinical features. Neutrophils from 14 MMM patients were assessed simultaneously for both JAK2 mutation and STAT3 phosphorylation status by immunoblotting. Strong expression of phosphorylation of STAT3 was seen in all 3 homozygotes and 4 of 5 heterozygotes, but only 1 of 6 with wild-type allele (p=0.026). Conclusions: Impaired neutrophil apoptosis in patients with MMM correlates with the functional presence of JAK2 V617F in an allele-dose dependent manner and STAT3 phosphorylation. The current observation supports a pathogenetic role for the specific mutation in sustaining clonal myeloproliferation.

Myeloid Blasts in Transformed JAK2-V617F Positive Myeloproliferative Disorders Are Frequently Negative for the JAK2-V617F Mutation.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 375-375 ◽  
Author(s):  
Alexandre Theocharides ◽  
Marjorie Boissinot ◽  
Richard Garand ◽  
François Girodon ◽  
Soon-Siong Teo ◽  
...  
Keyword(s):  
De Novo ◽  
Jak2 V617f ◽  
Myeloproliferative Disorders ◽  
Jak2 V617f Mutation ◽  
Jak2 Mutation ◽  
Allelic Ratio ◽  
Pcr Products ◽  
Blast Cells ◽  
V617f Mutation ◽  
De Novo Aml

Abstract Acute myeloid leukemia (AML) is a common complication of myeloproliferative disorders (MPDs). The role of the JAK2-V617F mutation in this process is unknown. We performed a retrospective analysis of DNA samples from MPD patients with secondary AML. We analysed DNA samples taken at the time of transformation to AML from 54 MPD patients (24 PV, 21 ET, 9 IMF). In addition, DNA samples taken at diagnosis of MPD were obtained in 21 of these patients. DNA was extracted from bone marrow or peripheral blood films, purified granulocytes or frozen cells. FACS sorting of blast cells, T cells and neutrophils was performed in some of the samples. The allelic ratio of JAK2-V617F was determined by allele-specific quantitative PCR (AS-PCR). We obtained AS-PCR data on 52/54 samples taken at the time of transformation (96%), whereas 2 samples did not yield PCR products: 24/52 samples were negative for JAK2-V617F (46%) and 28/52 were positive (54%). For 14/24 negative patients (58%) we had additional DNA samples taken at the time of MPD diagnosis and interestingly, 5 of these 14 patients (36%) were positive for JAK2-V617F at this earlier time point before AML transformation. This suggests that in these patients the JAK2-V617F positive clone was lost during the evolution to AML. Furthermore, comparison of the JAK2-V617F allelic ratios with the percentage of blast cells in patient samples positive at transformation revealed 8/28 cases where the JAK2-V617F allelic ratio was markedly lower than the percentage of blasts, e.g. 8%T-allele and 52% myeloid blast cells. In these patients a JAK2-V617F negative AML clone most likely co-exists with a JAK2-V617F positive MPD clone. To address the question whether the AML clone arose independently from the JAK2-V617F clone, we analyzed loss of heterozygosity on chromosome 9p (9pLOH) in one informative patient who displayed a high allelic ratio of mutant JAK2 at diagnosis (94%T). The CD15+ cells from this patient showed 9pLOH at diagnosis, as demonstrated with two independent microsatellite markers. In contrast, the FACS sorted blast cells at the time of transformation contained both parental alleles in the 9p region and were JAK2-V617F negative by AS-PCR. This excludes the possibility that the AML clone lost the JAK2V617F in the process of undergoing mitotic recombination at a stage heterozygous for JAK2-V617F. Analysis of additional patients is under way. In summary, we found in a cohort of 54 MPD patients, 13 patients initially positive for JAK2-V617F that transformed into JAK2-V617F negative AML. Although not confirmed in the one patient analyzed, we cannot exclude that other patients the JAK2-V617F positive MPD clone lost the JAK2 mutation during the process of transformation. Alternatively, the AML clone could have developed de novo from a JAK2-V617F negative progenitor or stem cell. The latter model has difficulties explaining the high incidence of de novo AML (8/54 patients), unless the JAK2-V617F negative progenitor already carried an as yet unknown mutation and was part of the MPD clone.

Tissue Factor and Soluble Markers of Platelet and Endothelial Activation in Essential Thrombocythemia: Relationship with Thrombosis and JAK2 V617F Mutation Status.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 2707-2707
Author(s):  
Francisco Cervantes ◽  
Eduardo Arellano-Rodrigo ◽  
Alberto Alvarez-Larran ◽  
Juan-Carlos Reverter ◽  
Neus Villamor ◽  
...  
Keyword(s):  
Tissue Factor ◽  
Essential Thrombocythemia ◽  
Plasma Concentrations ◽  
Jak2 V617f ◽  
Endothelial Activation ◽  
Jak2 V617f Mutation ◽  
Jak2 Mutation ◽  
Mutation Status ◽  
Significant Difference ◽  
V617f Mutation

Abstract There is increasing evidence that platelet and leukocyte activation plays an important role in the thrombotic complications of patients with essential thrombocythemia (ET), but the relationship of both thrombosis occurrence and JAK2 V617F mutation status with the levels of circulating tissue factor (TF) and of soluble markers of platelet and endothelial activation is not known. In 53 ET patients (26 of whom had a previous history of thrombosis), platelet TF expression and plasma levels of TF, soluble P-selectin (sP-selectin), soluble CD40 ligand (sCD40L), von Willebrand factor antigen (VWF:Ag), soluble thrombomodulin (sTM), D-dimer, and prothrombin fragment 1+2 (F1+2), measured by ELISA, were compared with those in matched healthy individuals and correlated with thrombosis occurrence and JAK2 V617F mutation status. ET patients with thrombosis had significantly higher levels of sP-selectin than patients without thrombosis and the controls, whereas ET patients without thrombosis had significantly higher levels than the controls (99.8 ± 47.1 ng/mL versus 70.6 ± 37.8 ng/mL versus 32.4 ± 11.9 ng/mL; p= 0.0001 for all comparisons). The same applied to sCD40L levels (226.7 ± 104.7 pg/mL in patients with thrombosis, 186.4 ± 92.1 pg/mL in patients without thrombosis, and 81.3 ± 22.0 pg/mL in controls; p= 0.0001 for all comparisons). Circulating VWF:Ag and F1+2 levels were higher in ET patients than in controls, but no significant difference was observed between patients with and without thrombosis. No differences in TF platelet expression, TF and sTM plasma concentrations were found between patients and controls. A positive correlation was observed between sP-selectin and F1+2, a marker of thrombin generation (r= 0.378, p= 0.01). Patients with the JAK2 mutation (22 out of 52 assessable patients), as compared with those with the wild-type allele, had significantly higher levels of sP-selectin (p= 0.002), sCD40L (p= 0.03), TF (p= 0.016), VWF:Ag (p= 0.0001), and sTM (p= 0.032). These results support a role for soluble markers of platelet activation in the thrombosis of ET as well as their potential to identify ET patients at greater risk of thrombosis. The association between JAK2 mutation and increased levels of TF and soluble markers of platelet and endothelial activation would suggest that the mutation could promote an enhanced prethrombotic state in ET.

Relationship between JAK2 V617F Mutation Status and Constitutive Mobilization of CD34-Positive Cells into Peripheral Blood in Patients with Chronic Myeloproliferative Disorder.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 2586-2586
Author(s):  
Francesco Passamonti ◽  
Elisa Rumi ◽  
Emanuela Boveri ◽  
Daniela Pietra ◽  
Laura Vanelli ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Cell Count ◽  
Peripheral Blood ◽  
Jak2 V617f ◽  
Myeloproliferative Disorder ◽  
Jak2 V617f Mutation ◽  
Jak2 Mutation ◽  
Mutation Status ◽  
Cell Counts ◽  
V617f Mutation

Abstract A gain-of-function mutation of the Janus kinase 2 (JAK2) gene has been recently reported in patients with polycythemia vera (PV), essential thrombocythemia (ET) and chronic idiopathic myelofibrosis (CIMF) [N Engl J Med. 2005 Apr 28;352(17):1779–90]. Abnormal trafficking of CD34-positive cells with increased numbers in the peripheral blood is found in CIMF and in advanced stages of other myeloproliferative disorders. To determine whether the unique JAK2 V617F mutation affects the mobilization of CD34-positive cells into peripheral blood, we studied the relationship between JAK2 mutation status, bone marrow and circulating CD34-positive cells in 72 patients diagnosed according to the WHO criteria. A quantitative real-time polymerase chain reaction (PCR)-based allelic discrimination assay was used for the quantitative detection of the JAK2 V617F alleles in circulating granulocytes. Bone marrow CD34-positive cells were quantitatively assed on paraffin immunostained sections, while circulating CD34-positive cells were enumerated by flow cytometry using a single-platform assay. Overall, 57% of the patients studied carried the JAK2 V617F mutation. Within these patients, median values for JAK2 V617F alleles in circulating granulocytes were as follows: 29% in PV, 4% in ET, 12% in prefibrotic CIMF, 27% in fibrotic CIMF, and 99% in post-PV myelofibrosis. The vast majority of circulating granulocytes were homozygous for the mutation in all but one of patients with post-PV myelofibrosis. Decreased numbers of bone marrow CD34-positive cells and increased counts of circulating CD34-positive cells were detected in patients with fibrotic bone marrow. The higher the degree of fibrosis, the higher the circulating CD34-positive cell count (P&lt;0.001) and the lower the bone marrow CD34-positive cell count (P&lt;0.01). All patients with PV, ET and prefibrotic CIMF, and 7 out of 21 patients with fibrotic CIMF had circulating CD34-positive cell counts lower than 10 x 106/L. Conversely, all patients with post-PV myelofibrosis had counts higher than 10 x 106/L. In univariate analysis, there was an inverse relationship between percentage of JAK2 V617F alleles and bone marrow CD34-positive cells (r=−0.35, P&lt;0.01), and a direct relationship between percentage of JAK2 mutant alleles and circulating CD34-positive cells (r=0.46, P=0.001). Multivariate analysis showed that disease category (P=0.0008) and percentage of JAK2 V617F alleles (P=0.03) were independently related to circulating CD34-positive cell counts. These observations suggest that the JAK2 V617F mutation might be involved in the constitutive mobilization of CD34-positive cells into peripheral blood that is found in patients with myeloproliferative disorder. Nonetheless, constitutive mobilization is present in a considerable portion of patients who do not carry the JAK2 mutation, pointing to additional pathogenetic mechanisms. Findings on patients with PV suggest that transition form heterozygosity to homozygosity for JAK2 V617F may represent an important step in the progression of PV to myelofibrosis. Thus, sequential evaluation of the percentage of JAK2 mutant alleles and enumeration of circulating CD34-positive cells may be useful for disease monitoring in PV.

JAK2 Mutation in Granulocytes and Platelets and X-Chromosome Gene-Based Clonal Analysis in Chronic Myeloproliferative Disorders.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 4896-4896
Author(s):  
Kohtaro Toyama ◽  
Norifumi Tsukamoto ◽  
Irisawa Hiroyuki ◽  
Akihiko Yokohama ◽  
Takayuki Saitoh ◽  
...  
Keyword(s):  
Mutation Rate ◽  
X Chromosome ◽  
Jak2 V617f ◽  
Myeloproliferative Disorders ◽  
Clonal Analysis ◽  
Jak2 V617f Mutation ◽  
P Value ◽  
Jak2 Mutation ◽  
Chronic Myeloproliferative Disorders ◽  
V617f Mutation

Abstract BCR/ABL-negative chronic myeloproliferative disorders (CMPDs) are considered to arise in a pluripotent progenitor cell. High prevalence of a point mutation in Janus Kinase 2 (JAK2) exon12 gene (JAK2-V617F) in CMPDs has been observed in many reports. Since most studies, however, are restricted mainly in granulocyte lineage, information about the JAK2 gene status in other cell lineage is limited. Heparinized peripheral blood was obtained from 49 patients with polycythemia vera (PV), 109 with essential thrombocytosis (ET), and 5 with chronic idiopathic myelofibrosis (CIMF). After centrifugation, platelets were collected from the upper plasma layer. The remaining blood layer was subjected to Ficoll-Hypaque density gradient centrifugation. Granulocytes were obtained from the pellet and T-cells recovered from the interface were further positively selected using either anti-CD3 or anti-CD4 immunoconjugated magnetic beads (Miltenyi Biotec, Germany). After DNA and RNA extraction, PCR amplified JAK2 exon 12 gene was sequenced to check the presence of JAK2-V617F mutation. Furthermore, X-chromosome linked clonal analysis using human androgen receptor (HUMARA) gene was carried out in 58 females. Correlation between the mutation status and clinical data was analyzed using statiscal software R (The R Development Core team). In PV, the frequency of JAK2-V617F mutation in granulocytes and platelets was 72.3 % and 74.3%, respectively (p-value 0.844). In ET, this mutation rate was 51.9% in granulocytes and 73% in platelets and the difference was significant (p-value 0.005). In all CMPDs, the cases showing JAK2-V617F mutation in granulocytes always had the mutation in platelets as well, but in one case of PV and 11 cases of ET, the JAK2-V617F mutation was observed only in platelets. T cell fraction was negative for JAK2-V617F mutation in all cases examined. White blood cell count was significantly higher in cases of JAK2-V617F mutation in their platelets compared to that in cases without this mutation (12.6 × 109/l vs. 9.2 × 109/l), but hemoglobin level and platelet count did not differ between the two groups (14.9g/l vs. 14.6 g/l, 81.4 × 109/l vs. 95.2 × 109/l). In addition, cases showing this mutation in platelets were more likely to be associated with thrombosis than cases showing the wild type gene (p-value 0.018). On clonal analyses using the HUMARA gene, 6/8 patients with PV, 15/27 patients with ET, and 1/1 patient with CIMF demonstrated a monoclonal pattern in their granulocytes. Interestingly, in 23 cases showing the JAK2-V617F mutation, 7 patients showed the polyclonal HUMARA pattern; in 13 cases without mutation, 7 showed the monoclonal HUMARA pattern. The discrepancy of JAK2-V617F mutation rate between platelets and granulocytes in ET suggests that analysis of platelet fraction is advantageous for detecting the mutation. This finding also suggests that the JAK2 mutation could be involved only in megakaryocyte lineage in some ET patients. HUMARA analysis confirmed that some ET patients with monoclonal disease lack the JAK2-V617F mutation, which is consistent with previous reports.

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.

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.

JAK2 V617F mutational status predicts progression to large splenomegaly and leukemic transformation in primary myelofibrosis

Blood ◽  
2007 ◽  
Vol 110 (12) ◽  
pp. 4030-4036 ◽  
Author(s):  
Giovanni Barosi ◽  
Gaetano Bergamaschi ◽  
Monia Marchetti ◽  
Alessandro M. Vannucchi ◽  
Paola Guglielmelli ◽  
...  
Keyword(s):  
Jak2 V617f ◽  
Primary Myelofibrosis ◽  
Jak2 V617f Mutation ◽  
Confirmatory Test ◽  
Progression Rate ◽  
Homozygous Mutation ◽  
Leukemic Transformation ◽  
Jak2 Mutation ◽  
Mutational Status ◽  
V617f Mutation

Abstract Few investigators have evaluated the usefulness of the JAK2 V617F mutation for explaining the phenotypic variations and for predicting the risk of major clinical events in primary myelofibrosis (PMF). In a transversal survey we assayed by allele-specific polymerase chain reaction (PCR) the JAK2 V617F mutational status in 304 patients with PMF. Multiple DNA samples were collected prospectively from 64 patients, and a highly sensitive quantitative PCR was used as a confirmatory test. In a longitudinal prospective study we determined the progression rate to clinically relevant outcomes in 174 patients who had JAK2 mutation determined at diagnosis. JAK2 V617F was identified in 63.4% of patients. None of the V617F-negative patients who were sequentially genotyped progressed to become V617F positive, whereas progression rate from heterozygous to homozygous mutation was 10 per 100 patient-years. JAK2 V617F mutation contributed to hemoglobin, aquagenic pruritus, and platelet count variability, whereas homozygous mutation was independently associated with higher white blood cell count, larger spleen size, and greater need for cytoreductive therapies. Adjusting for conventional risk factors, V617F mutation independently predicted the evolution toward large splenomegaly, need of splenectomy, and leukemic transformation. We conclude that JAK2 V617F genotype should be considered in any future risk stratification of patients with PMF.

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