The JAK2 V617F mutational status and allele burden – authors’ reply

2015 ◽  
Vol 136 (3) ◽  
pp. 691-692 ◽  
Author(s):  
Martyna Borowczyk ◽  
Marzena Wojtaszewska ◽  
Krzysztof Lewandowski ◽  
Lidia Gil ◽  
Maria Lewandowska ◽  
...  
Keyword(s):  
Jak2 V617f ◽  
Allele Burden ◽  
Mutational Status

Correlations Between TET2 Mutation and Clinicohematologic Parameters in Myeloproliferative Neoplasms

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 1455-1455
Author(s):  
Jung Sook Ha ◽  
Jae Hee Lee ◽  
Sung Gyun Park ◽  
Nam Hee Ryoo ◽  
Dong Suk Jeon ◽  
...  
Keyword(s):  
Conflicts Of Interest ◽  
Myeloproliferative Neoplasms ◽  
Direct Sequencing ◽  
Jak2 V617f ◽  
Putative Tumor Suppressor Gene ◽  
Allele Burden ◽  
Frame Shift ◽  
Mutational Status ◽  
Tet2 Mutation ◽  
Disease Specific

Abstract Abstract 1455 Background: Since the acquired somatic mutation, JAK2 V617F, was discovered as a first molecular marker of myeloproliferative neoplasms (MPN), and it has been detected variably in each MPN subtypes. However, JAK2 V617F does not found in all of MPN cases and not necessarily specific to a particular clinicpathologic entity. Recently, mutation of the putative tumor suppressor gene, Ten-Eleven-Translocation-2(TET2), has been identified in MPN patients. However, the frequency of TET2 mutation or its relationship with JAK2 V617F mutation or pathologic function in MPN has not been concluded, yet. The aim of our study was to evaluate the frequency of TET2 in MPN patients, and whether there is any correlation of TET2 mutation with JAK2V617F mutation or the clinicohematologic parameters. Materials and Methods: Total 99 adult MPN patients (18 PV, 62 ET, 11 PMF and 8 MPN unclassified) whose bone marrow cells had been stored from 2007 to 2010 at point of first diagnosis were included in this study. Hematological diagnoses and subtyping were reconfirmed according to the 2008 WHO classification and clinicohematologic datas were collected from patient records. Direct sequencing for TET2(exon3–11) and JAK2 (exons 12 and 14) were performed using an ABI 3730XL DNA analyzer. The JAK2V617F allele burdens were determined by pyrosequencing for samples available and MPL was analyzed by allele-specific PCR. Results: The overall TET2 mutational frequency was 12.1%, and disease-specific mutational frequencies were 22.2% in PV, 9.7% in ET and 18.2% in PMF. The found mutations included 11 mutations, 7 frame-shift (p.Lys95AsnfsX18, p.Gln967AsnfsX40, p.Lys1022GlufsX4, p.Asp1314MetfsX49, p.Gln1534AlafsX43, p.Tyr1618LeufsX4, p.Leu1609GlufsX45), 1 nonsense (p.Gly1735X), 1 missense (Q599R) and 2 splicing mutations (c.3409+1G>T, c.4044+2insT). Those mutations most frequently involved exon 3(four mutations) and exon 11(four mutaions), and rarely intron 3, intron 8 and exon 7. None of the mutations were associated with a karyotypically apparent 4q24 rearrangement. All patients were also screened for JAK2 V617F, and the overall JAK2 V617F positive rate was 68%(94.4% in PV, 69.4% in ET, 45.5% in PMF and 37.5% in MPN, unclassified). All TET2 mutations occurred in JAK2 V617F positive cases. JAK2 exon12 mutation was not found in all patients. MPL W515L was found in one ET patient who also carried JAK2V617F, but not TET2 mutation. Information on JAK2 V617F allele burden was available in 78 patients. Considering all 99 patients, the patient age, hematologic indexes (leukocyte count, neutrophil fraction, lymphocyte fraction, monocyte fraction, Hb, Hct and platelet count), the frequency of organomegaly, marrow fibrosis or thrombotic/hemorrhagic complications were not different according to carrying TET2 mutation. However, TET2 mutation was more frequently found in JAK2 V617F carriers than non-carriers (P=0.008), but JAK2 V617F allele burden did not correlated with the presence of mutant TET2. When analysis was performed for each PV, ET, and PMF (no TET2 mutation in MPN-unclassifiable patients), correlation between TET2 and JAK2 V617F mutational status was not found in each subtypes (P=0.078 in PV, P=0.099 in ET and P=0.182 in PMF). However, the JAK2 V617F allele burden was significantly higher in PMF harboring TET2 mutation than PMF patients did not (88.0 ± 4.3% vs 19.1 ± 28.7%, P=0.034). In statistical analysis for the correlations of clinicohematologic parameters with TET2 mutation in each PV, ET and PMF patients, only a few statistically significant results were identified. The presence of TET2 mutation was correlated with high Hct in PMF (47.4 ± 5.4 vs 25.5 ± 6.2, P=0.037), and TET2 positive ET patients showed relatively higher frequency of organomegaly compared to ET patients without TET2 mutation (50% vs 19.6%, P=0.018). Conclusions: The overall and disease-specific frequencies of TET2 mutation in our study are similar with previous studies, and frame-shift mutation is the most frequent mutation type. There is no specific relationship between JAK2 V617F and TET2 mutation occurrence, but TET2 mutant PMF has higher JAK2 V617F allele burden than non-mutant. TET2 mutation is also associated with a higher Hct in PMF and higher frequency of organomegaly in ET. Larger scale studies involving more MPN patients are needed. Disclosures: No relevant conflicts of interest to declare.

The JAK2 V617F mutational status and allele burden

2015 ◽  
Vol 136 (3) ◽  
pp. 690 ◽  
Author(s):  
Shanshan Liang ◽  
Yanhong Zhou
Keyword(s):  
Jak2 V617f ◽  
Allele Burden ◽  
Mutational Status

Platelet Adhesion Under Flow Condition in Patients with Essential Thrombocythemia (ET) and Polycythemia Vera (PV): Analysis According to the Mutational Status

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 766-766
Author(s):  
Alfonso Vignoli ◽  
Serena Tessarolo ◽  
Marina Marchetti ◽  
Sara Gamba ◽  
Francesca Piras ◽  
...  
Keyword(s):  
Flow Condition ◽  
Thrombus Formation ◽  
Hematological Parameters ◽  
Jak2 V617f ◽  
Jak2 V617f Mutation ◽  
Allele Burden ◽  
Mutational Status ◽  
Wbc Count ◽  
Rbc Count

Abstract Background: ET and PV are two myeloproliferative neoplasms characterized by a high incidence of both arterial and venous thrombosis, and microcirculatory disturbances. So far, no studies have been performed to characterize ET and PV patient platelet (PLT) adhesion properties in flow conditions, an index of thrombus formation capacity in vitro (Platelets 2012; 23(3): 229-42). Aim: In this study, in a cohort of patients with ET or PV, we wanted to evaluate the PLT adhesiveness in vitro by a dynamic method and to estimate whether this property is influenced by any of the three somatic mutations, i.e. JAK2 V617F, Calreticulin (CalR) and MPL, typical of these diseases, of which, the JAK2 V617F mutation has a significant association with thrombosis occurrence, while CalR and MPL mutations have not. Further, the relations of PLT adhesion to main hematological parameters and to cytoreductive hydroxyurea (HU) therapy were also considered. Patients and Methods: Sixty-nine patients, i.e. 47 ET (20 M/27 F; mean age 60 years, range 33-86) and 22 PV (13 M/9 F; mean age 65 years, range 46-80), and 26 healthy controls (13 M/13 F; 44 years, range 27-61) were included into the study. For the adhesion assay, peripheral venous whole blood was drawn in sodium citrate, recalcified in the presence of heparin, and perfused over a collagen-coated surface for 4 min at a shear rate of 1,000 s-1. PLTs were then stained with an anti-CD62P (P-selectin)-FITC antibody as a PLT activation index, and annexin V-AlexaFluor647 to detect PLT procoagulant phosphatidylserine expression. After staining, images of adherent platelets in random fields were taken using phase contrast and fluorescence imaging with the EVOS® fluorescence microscope (Life Technologies). Results are expressed as the mean±SEM of the percentage of area covered by all PLTs (% coverage), or as the % of adherent PLTs positive for either P-selectin or phosphatidylserine. Main hematological parameters (i.e. PLT count, WBC count, RBC count, Hb, Hct, MCV, MPV), therapeutic regimens, and mutational status (JAK2 V617F, CalR, or MPL) were also recorded. Statistical analysis was performed by SPSS® (IBM) software package. Results: PLT adhesion was significantly (p<0.01) greater in both ET (44.6±2% coverage) and PV patients (45.6±2.7%) compared to controls (36±2.1%). The analysis of PLT adhesion according to the mutational status shows that, in ET patients, PLT adhesion was greatest in JAK2 V617F mutation carriers (n=22), followed by triple negative (n=7), and CalR-positive (n=15). The only 3 MPL-positive ET patients had the lowest PLT adhesion values. In PV patients, those with >50% JAK2 V617F allele burden carriers (n=8; 52.5±2% coverage) presented a significantly higher PLT adhesion than those with <50% allele burden (n=14; 42.4±3.9, p<0.05). Notably, in both ET and PV patients, while the overall PLT adhesion was significantly increased, the percentage expression of P-selectin by adherent PLTs (~ 75%) was not statistically different from that of control subjects. Differently, the expression of procoagulant phosphatidylserine on adherent PLTs was reduced in both ET (p<0.001) and PV patients (p=n.s.) compared to controls. Among hematological parameters, in ET patients, a significant (p<0.001) correlation was found between PLT adhesion with PLT count, but not with WBC count, RBC count, Hb, Hct, MCV, or MPV. As regard to treatments, a significant reduction in PLT adhesion was associated with cytoreductive treatment with HU (p<0.05) in patients with PV, but not with ET. Conclusions: ET and PV platelets show a greater thrombus formation capacity in vitro in a dynamic flow condition, as measured by an increase in adhesion to collagen. This capacity is significantly augmented according to the JAK2 V617F mutational allele burden and decreased by HU therapy. A prospective study of the PLT thrombus formation potential in a dynamic model is ongoing to evaluate the predictive value of this parameter on the thrombotic risk of ET and PV patients. Project funded by "AIRC IG2013" grant Nr. 14505 from the "Italian Association for Cancer Research (A.I.R.C.)". Disclosures No relevant conflicts of interest to declare.

scholarly journals A comparison of qPCR and ddPCR used for quantification of the JAK2 V617F allele burden in Ph negative MPNs

2018 ◽  
Vol 97 (12) ◽  
pp. 2299-2308 ◽  
Author(s):  
Dorota Link-Lenczowska ◽  
Niels Pallisgaard ◽  
Sabrina Cordua ◽  
Magdalena Zawada ◽  
Sylwia Czekalska ◽  
...  
Keyword(s):  
Jak2 V617f ◽  
Allele Burden

JAK2 Mutations at Exon 12 and 14 in Polycythemia Vera and Idiopathic Erythrocytosis: Incidence and Correlation with Clinical Characteristics.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 2532-2532
Author(s):  
Carlos Besses ◽  
Luz Martínez-Avilés ◽  
Alberto Alvarez-Larrán ◽  
Francisco Cervantes ◽  
Juan Carlos Hernández-Boluda ◽  
...  
Keyword(s):  
Polycythemia Vera ◽  
Cell Sorting ◽  
Clinical Characteristics ◽  
Clinical Phenotype ◽  
Cell Lineage ◽  
Jak2 V617f ◽  
Free Survival ◽  
Mutational Status ◽  
Cell Subpopulations ◽  
Idiopathic Erythrocytosis

Abstract Introduction. Exon 12 mutations of the JAK2 gene have been described in polycythemia vera (PV) and idiopathic erythrocytosis (IE) patients. These patients display a clinical phenotype different to that observed in V617F-positive PV patients, but no information is available on their clinical outcome. Patients and methods. Twenty JAK2 V617F-negative PV or IE patients and 86 V617F-positive PV patients were assessed for exon 12 and exon 14 mutations. Analysis of cell lineage mutational status was assessed following cell sorting. Aim. To analyze the presence of JAK2 mutations at exon 12 and 14 in a cohort of V617F-negative PV and IE patients and to correlate them with the patient clinicohematological and evolutive data. Results. Exon 12 mutations were detected in 4 (20%) V617F-negative patients (K539L, two cases, N542_E543del and H538_K539delinsL, one case each). In 16 patients, no mutations were found in either exon 12 or exon 14. Additional mutations in exon 14 were found in two V617F-positive patients. Two patients with exon 12 mutations developed thrombosis after diagnosis, with the probability of thrombosis-free survival being 75% at 5 years. Another patient with exon 12 mutation developed myelofibrosis at 20 years of PV diagnosis. JAK2 mutations were present in granulocytes, platelets and monocytes, but not in lymphocytes or NK cells. Conclusions. Patients harboring exon 12 mutations represent a subset of JAK2 V617F-negative PV or IE patients. These patients have initial hematological data different from V617F-positive patients, but they do not differ with regard to thrombosis development and myelofibrotic transformation. Table 1: JAK2 exon 12 and exon 14 mutations in blood cell subpopulations. Mutation Granulocytes Platelets CD14+ CD3+ CD19+ CD56+ * exon 12; # exon 14; + indicates the presence of the mutation; − indicates no detectable mutation ; ND not determined Patient 1* K539L (AAA →TTA) + + − − − − Patient 2* K539L (AAA →CTA) + + + − − − Patient 3* H538_K539delinsL + + ND − − ND Patient 4* N542_E543del + + + − − − Patient 5# V617F (GTC →TTT) + + − − − ND C618R (TGT →CGT) + + − − − ND Patient 6# V617F (GTC →TTC) + + + − − ND C616C (TGT →TGC) + + + − − ND

Identification of Homozygous JAK2V617F Mutation in Unfractioned Blood Samples in a Substantial Proportion of Myeloproliferative Disorders: Long Term Follow-Up Study.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 4644-4644
Author(s):  
Irina Panovska ◽  
Nadica Matevska ◽  
Martin Ivanovski ◽  
Sanja Trajkova ◽  
Aleksandar Stojanovik ◽  
...  
Keyword(s):  
Jak2 V617f ◽  
Jak2v617f Mutation ◽  
Study Group ◽  
Hematopoietic Progenitors ◽  
Blood Samples ◽  
Allele Burden ◽  
Long Term Follow Up ◽  
Thrombotic Complications

Abstract The discovery of the activating V617F mutation in the JAK2 tyrosine kinase gene in patients with myloproliferative disorders (MPD) provides a major breakthrough in the understanding of the pathogenesis, proving clonality and securing diagnosis of these diseases. The JAK2 V617F allele is an acquired somatic disease allele that arises in hematopoietic progenitors and confers a selective growth advantage. The mutation has been traced to a primitive stem cell that is capable of erythroid and myeloid differentiation. The data for the potential involvement of the B and T lymphocytes with the JAK2V617F mutation are still inconsistent. We present the results from the study designed the evaluate the prevalence of the JAK2V617F mutation in MPDs patients in our population and to investigate whether MPD patients that carry the JAK2V617F mutation differ in clinical course and outcome from JAK2V617F negative MPD patients. The study group consisted of 64 living MPD patients diagnosed according to standard WHO criteria for diagnosis of MPD (26 patients were diagnosed as polycythemia vera (PV), 34 as essential thrombocythemia (ET), 6 as idiopatic myelofibrosis (MF) and 8 were classified as atypical MPD) with the median follow-up of 7,4 years. DNA samples were obtained from unfractionated blood samples and the frequency of V617F JAK2 mutation was analyzed by allele-specific PCR assay. The mutant allele burden in mutation positive samples was analyzed by DNA sequencing. Our results showed that the JAK2 V617F mutation was present in 79% of patients with PV (36% were homozygous for the mutation), 58% with ET (11% homozygous), 69% with MF (28% homozygous) and in 33% of patients with atypical MPD. The mutant JAK2V617F allele burden was greater than 95% in two PV patients, which in the presence of 27% lymphocytes in the peripheral blood of the patients indicate lymphocytes involvement with the mutation. The high frequency of observed homozygosity for JAK2V617F in our study group was probably due to the long disease duration (median follow-up 11,4 years) and favors the theory of a time dependent increase in clonal dominance. Correlations of clinical and laboratory features at diagnosis and subsequent follow-up, including incidence of thrombo-hemorrhagic events, disease transformation and survival of JAK2V617F-positive and JAK2V617F-negative patients did not reveal significant differences except for the incidence of thrombotic complications. The JAK2V617F positive group had a higher incidence of thrombotic complications (30%) compared with the JAK2-V617F-negative group (14%, P< 0.05). Although we observed a disparity in the incidence of the JAK2V617F mutation in different MPD entities in our population with respect to the expected frequency of JAK2V617F from the literature, our results confirm the diagnostic significance of the JAK2V617F mutation in MPDs and support the notion that patients with this mutation should be classified in a new entity of MPDs. Identification of homozygous JAK2V617F mutation in unfractionated blood samples in a substantial proportion of long term follow-up MPD patients, together with the identification of the mutant JAK2V617F allele burden greater than 95% in two PV patients, suggests that acquisition of the JAK2V617F mutation arises in early multilineage hematopoietic progenitors and warrants further investigation.

Polycythemia Vera as a Predisposing Factor for Aortic Stenosis: Prevalence and Correlation with Blood Cells Count and Mutational Status

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 5247-5247
Author(s):  
Ri ta Barone ◽  
Clementina Caracciolo ◽  
Rosario di Maggio ◽  
Giovanni Fazio ◽  
Luciana d’Angelo ◽  
...  
Keyword(s):  
Relative Risk ◽  
Aortic Stenosis ◽  
Blood Cell ◽  
Polycythemia Vera ◽  
Blood Cells ◽  
Jak2 V617f ◽  
Laboratory Findings ◽  
Mutational Status ◽  
Adhesive Molecules

Abstract The association between Polycythemia Vera (PV) and thrombosis is multi-factorial involving the complex interaction between activated leukocytes, platelets and endothelium. Recent reports have postulated that PV patients may over express adhesive molecules on red cell surface, likely by JAK2 mutation (Wautier M et al. Blood.2007;110(3):894–901). This process activates endothelium with production of vascular growth factors and other mechanisms leading to atherosclerosis. Aortic Stenosis (AS) is the commonest valvular heart disease in western countries; its pathogenesis is mainly related to a degenerative process sharing many characteristics with atherosclerosis. At the present is not known whether patients with PV are at high risk of developing AS. Objective of the study. We perform a case-control study for evaluating rate of AS and its correlation with blood cells count and mutational status in patients with PV. Materials and methods. Prevalence of AS among PV patients have been compared with control patients matched for age, cardiovascular risk factors (hypertension, hyperlipidemia, diabetes, smoke and alcohol abuse) and coexisting cardiac diseases (i.e. heart failure). Diagnosis of PV has been posted accordingly to PVSG criteria. Diagnosis and severity of AS has been posted by echocardiography: stenosis with a valve area <1.0 cm2 has been considered severe. Results. Over a period of 18 months we recruited 43 PV patients (28 males and 15 females) and 74 controls. No differences were found in regard of the above cited characteristics; median age was 66.7 among PV patients and 68.2 among controls. The average duration of PV was 5.7 years with an average follow-up of 2.5 years. Most of the PV patients were on antiplatelet/anticoagulant therapy (27/43, 62.7%) and have been treated with cytoreductive therapy. Twelve (27.9%) had a thrombotic event before PV diagnosis; 4 (9.3%) developed thrombosis during the follow-up (median 1.3 years). A moderate/severe AS was found in 11 PV patients (25.6%) in comparison to 4 (5.4%) in control group (P= 0.023), thus giving a Relative Risk of 4.7. Among PV patients, the multivariate analysis did not show any correlation regarding JAK2 V617F mutational status, duration of disease, previous thrombosis, cytoreductive therapy and other common cardiovascular factors. Comparison of laboratory findings is reported in Table 1; a not significant trend was demonstrated in favor of patients with elevated hematocrit (>55%). Conclusions. Our study clearly shows that PV patients carry a fourfold risk of developing AS, without a clear association with blood cell alterations or previous thrombosis. Whether high prevalence of AS may be related to expression of adhesive molecules on red cells or altered share stress is currently under investigation. Table 1. Comparison of laboratory findings between PV patients with and without AS Laboratory parameter* PV patients with AS (11) PV patients without AS (32) Relative Risk P value *At diagnosis Legend: PV (Polycythemia Vera), AS (Aortic Stenosis) White blood cell×109/L (mean± SD) 9520 ± 1230 12.900 ± 2120 0.73 .078 Hemoglobin, g/dL (mean ± SD) 17.5 ± 1.3 17.1 ± 1.2 1.02 .088 Hematocrit, % (mean ± SD) 56.2 ± 0.6 51.1 ± 0.8 1.1 0.06 Platelets × 109/L(mean ± SD) 415.9 ± 43 353 ± 55 1.1 0.76 JAK2 V617F, n/N (%) 11/11 (100%) 31/32 (97%) - -

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