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Dvořáček L, Marková J, Holoubek A, Grebeňová D, Kundrát D, Kuželová K, Schwarz J. A novel germline hyperactivating JAK2 mutation L604F. Ann Hematol 2023; 102:2725-2734. [PMID: 37639050 PMCID: PMC10492870 DOI: 10.1007/s00277-023-05423-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Accepted: 08/19/2023] [Indexed: 08/29/2023]
Abstract
Somatic JAK2 mutations are the main molecular cause of the vast majority of polycythemia vera (PV) cases. According to a recent structural model, the prevalent acquired V617F mutation improves the stability of the JAK2 dimer, thereby enhancing the constitutive JAK2 kinase activity. Germline JAK2 mutations usually do not largely alter JAK2 signaling, although they may modulate the impact of V617F. We found an unusual germline JAK2 mutation L604F in homozygous form in a young PV patient, along with a low allele burden JAK2 V617F mutation, and in her apparently healthy sister. Their father with a PV-like disease had L604F in a heterozygous state, without V617F. The functional consequences of JAK2 L604Fmutation were compared with those induced by V617F in two different in vitro model systems: (i) HEK293T cells were transfected with plasmids for exogenous JAK2-GFP expression, and (ii) endogenous JAK2 modifications were introduced into HeLa cells using CRISPR/Cas9. Both mutations significantly increased JAK2 constitutive activity in transfected HEK293T cells. In the second model, JAK2 modification resulted in reduced total JAK2 protein levels. An important difference was also detected: as described previously, the effect of V617F on JAK2 kinase activity was abrogated in the absence of the aromatic residue F595. In contrast, JAK2 hyperactivation by L604F was only partially inhibited by the F595 change to alanine. We propose that the L604F mutation increases the probability of spontaneous JAK2 dimer formation, which is physiologically mediated by F595. In addition, L604F may contribute to dimer stabilization similarly to V617F.
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Affiliation(s)
- Lukáš Dvořáček
- Department of Proteomics, Institute of Hematology and Blood Transfusion, Prague, Czech Republic
| | - Jana Marková
- Clinical Department, Institute of Hematology and Blood Transfusion, Prague, Czech Republic
| | - Aleš Holoubek
- Department of Proteomics, Institute of Hematology and Blood Transfusion, Prague, Czech Republic
| | - Dana Grebeňová
- Department of Proteomics, Institute of Hematology and Blood Transfusion, Prague, Czech Republic
| | - David Kundrát
- Department of Genomics, Institute of Hematology and Blood Transfusion, Prague, Czech Republic
| | - Kateřina Kuželová
- Department of Proteomics, Institute of Hematology and Blood Transfusion, Prague, Czech Republic.
| | - Jiří Schwarz
- Clinical Department, Institute of Hematology and Blood Transfusion, Prague, Czech Republic
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The Contribution of JAK2 46/1 Haplotype in the Predisposition to Myeloproliferative Neoplasms. Int J Mol Sci 2022; 23:ijms232012582. [PMID: 36293440 PMCID: PMC9604447 DOI: 10.3390/ijms232012582] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Revised: 10/13/2022] [Accepted: 10/15/2022] [Indexed: 11/17/2022] Open
Abstract
Haplotype 46/1 (GGCC) consists of a set of genetic variations distributed along chromosome 9p.24.1, which extend from the Janus Kinase 2 gene to Insulin like 4. Marked by four jointly inherited variants (rs3780367, rs10974944, rs12343867, and rs1159782), this haplotype has a strong association with the development of BCR-ABL1-negative myeloproliferative neoplasms (MPNs) because it precedes the acquisition of the JAK2V617F variant, a common genetic alteration in individuals with these hematological malignancies. It is also described as one of the factors that increases the risk of familial MPNs by more than five times, 46/1 is associated with events related to inflammatory dysregulation, splenomegaly, splanchnic vein thrombosis, Budd–Chiari syndrome, increases in RBC count, platelets, leukocytes, hematocrit, and hemoglobin, which are characteristic of MPNs, as well as other findings that are still being elucidated and which are of great interest for the etiopathological understanding of these hematological neoplasms. Considering these factors, the present review aims to describe the main findings and discussions involving the 46/1 haplotype, and highlights the molecular and immunological aspects and their relevance as a tool for clinical practice and investigation of familial cases.
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Ansar S, Malcolmson J, Farncombe KM, Yee K, Kim RH, Sibai H. Clinical implementation of genetic testing in adults for hereditary hematologic malignancy syndromes. Genet Med 2022; 24:2367-2379. [PMID: 36112138 DOI: 10.1016/j.gim.2022.08.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Revised: 08/10/2022] [Accepted: 08/11/2022] [Indexed: 11/25/2022] Open
Abstract
PURPOSE As research on hereditary hematologic malignancy syndromes (HHMS) are accumulating, cancer genetics clinics are identifying more adult hematology patients with an inherited component to their disease. However, investigations for HHMS are complex, and there is no formal consensus on genetic testing criteria. METHODS We developed genetic testing criteria for adult hematology patients through a comprehensive literature review and our experience at the Princess Margaret Cancer Centre. We validated our criteria by applying them retrospectively to patients referred to our clinic for HHMS assessment. RESULTS Our genetic testing criteria are comprehensive of myeloid malignancies, lymphoid malignancies, and bone marrow failure, including age at diagnosis, family history, and genetic test results in blood and bone marrow. Of the 104 patients who met the criteria, 26% had at least 1 actionable variant in any gene associated with an increased risk of cancer and 13% had an actionable variant resulting in an HHMS diagnosis. A total of 15 patients had incidental findings, including 11 patients with a pathogenic variant associated with carrier status for an autosomal recessive disorder and 4 patients with a mosaic result. CONCLUSION Our high gene positivity rate shows the utility of a broad approach to germline testing in an adult hematology population.
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Affiliation(s)
- Safa Ansar
- Division of Medical Oncology and Hematology, Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada
| | - Janet Malcolmson
- Bhalwani Familial Cancer Clinic, Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada; Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Kirsten M Farncombe
- Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada
| | - Karen Yee
- Division of Medical Oncology and Hematology, Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada; Department of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Raymond H Kim
- Division of Medical Oncology and Hematology, Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada; Bhalwani Familial Cancer Clinic, Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada; Ontario Institute for Cancer Research, Toronto, Ontario, Canada; Division of Clinical and Metabolic Genetics, The Hospital for Sick Children, Toronto, Ontario, Canada; Sinai Health System, Toronto, Ontario, Canada; Department of Medicine, University of Toronto, Toronto, Ontario, Canada.
| | - Hassan Sibai
- Division of Medical Oncology and Hematology, Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada; Department of Medicine, University of Toronto, Toronto, Ontario, Canada.
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Stockklausner C, Duffert CM, Cario H, Knöfler R, Streif W, Kulozik AE. Thrombocytosis in children and adolescents-classification, diagnostic approach, and clinical management. Ann Hematol 2021; 100:1647-1665. [PMID: 33712866 PMCID: PMC8195939 DOI: 10.1007/s00277-021-04485-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2020] [Accepted: 03/02/2021] [Indexed: 11/30/2022]
Abstract
Secondary thrombocytosis is a frequent secondary finding in childhood infection and inflammation. Primary hereditary thrombocytosis may be caused by germline mutations within the genes encoding key regulators of thrombopoiesis, i.e., thrombopoietin (THPO) and its receptor c-MPL (MPL) or the receptor's effector kinase Januskinase2 (JAK2). Furthermore, somatic mutations in JAK2, MPL, and in the gene-encoding calreticulin (CALR) have been described to act as driver mutations within the so-called Philadelphia-negative myeloproliferative neoplasms (MPNs), namely essential thrombocythemia (ET), polycythemia vera (PV), and primary myelofibrosis (PMF). Increasing knowledge on the molecular mechanisms and on the clinical complications of these diseases is reflected by the WHO diagnostic criteria and European LeukemiaNet (ELN) recommendations on the management of adult MPN. However, data on childhood thrombocytosis are rare, and no consensus guidelines for pediatric thrombocytosis exist. Current literature has highlighted differences in the epidemiology and molecular pathogenesis of childhood thrombocytosis as compared to adults. Furthermore, age-dependent complications and pharmacological specificities suggest that recommendations tailored to the pediatric population are necessary in clinical practice. Here we summarize literature on classification, diagnostics, and clinical management of childhood thrombocytosis.
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Affiliation(s)
- Clemens Stockklausner
- Department of Pediatric Oncology, Hematology and Immunology and Hopp Children's Cancer Research Center (KiTZ), Heidelberg University and German Cancer Research Center (DKFZ), Heidelberg, Germany. .,Department of Pediatrics, Garmisch-Partenkirchen Hospital, Auenstraße 6, 82467, Garmisch-Partenkirchen, Germany.
| | - C M Duffert
- Department of Pediatrics, Heidelberg University, Heidelberg, Germany
| | - H Cario
- Department of Pediatrics and Adolescent Medicine, Ulm University Medical Center, Ulm, Germany
| | - R Knöfler
- Department of Pediatric Hematology and Oncology, Medical Faculty of Technical University, Dresden, Germany
| | - W Streif
- Department of Pediatrics, Medical University of Innsbruck, Innsbruck, Tirol, Austria
| | - A E Kulozik
- Department of Pediatric Oncology, Hematology and Immunology and Hopp Children's Cancer Research Center (KiTZ), Heidelberg University and German Cancer Research Center (DKFZ), Heidelberg, Germany
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Vočanec D, Prijatelj T, Debeljak N, Kunej T. Genetic variants of erythropoietin (EPO) and EPO receptor genes in familial erythrocytosis. Int J Lab Hematol 2018; 41:162-167. [PMID: 30507031 PMCID: PMC7379665 DOI: 10.1111/ijlh.12949] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Revised: 10/02/2018] [Accepted: 10/30/2018] [Indexed: 12/17/2022]
Abstract
OBJECTIVES Erythrocytosis is characterized by the expansion of erythrocyte compartment including elevated red blood cell number, hematocrit, and hemoglobin content. Familial erythrocytosis (FE) is a congenital disorder with different genetic background. Type 1 FE is primary FE caused by mutation in erythropoietin receptor gene (EPOR). Type 2-5 FE are secondary FEs caused by mutations of genes involved in oxygen sensing pathway important for erythropoietin (EPO) regulation. In the present study, we summarized associations between EPOR and EPO gene variations with development of FE and searched for genetic variants located within regulatory regions. METHODS Publications reporting EPOR and EPO sequence variants associated with FE or clinical features of erythrocytosis were retrieved from PubMed and WoS. In silico, sequence reanalysis was performed using Ensembl genomic browser, release 89 to screen for variants located within regulatory regions. RESULTS To date, 28 variants of the EPOR and seven variants of the EPO gene have been associated with erythrocytosis or upper hematocrit. Sequence variants were also found to be present within regulatory regions. CONCLUSIONS Role of variants in regulatory regions of the EPO gene should be further investigated.
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Affiliation(s)
- Danijela Vočanec
- Department of Animal Science, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia.,Institute of Biochemistry, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Tinkara Prijatelj
- Department of Animal Science, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia.,Institute of Biochemistry, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Nataša Debeljak
- Institute of Biochemistry, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Tanja Kunej
- Department of Animal Science, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia
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Aral B, Courtois M, Ragot S, Bourgeois V, Bottolier-Lemallaz E, Briandet C, Girodon F. Germline JAK2 L611S mutation in a child with thrombocytosis. Haematologica 2018; 103:e372-e373. [PMID: 29567786 DOI: 10.3324/haematol.2018.188995] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Affiliation(s)
- Bernard Aral
- Laboratoire de génétique chromosomique et moléculaire, Pôle Biologie, CHU de Dijon, France
| | - Martine Courtois
- Service d'Hématologie Biologique, Pôle Biologie, CHU de Dijon, France
| | - Sylviane Ragot
- Laboratoire de génétique chromosomique et moléculaire, Pôle Biologie, CHU de Dijon, France
| | | | | | - Claire Briandet
- Service d'Immuno-Hématologie Pédiatrique, CHU de Dijon, France
| | - François Girodon
- Service d'Hématologie Biologique, Pôle Biologie, CHU de Dijon, France .,Inserm U1231, Université de Bourgogne, Dijon, France
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Pemmaraju N, Moliterno AR. From Philadelphia-Negative to JAK2-Positive: Effect of Genetic Discovery on Risk Stratification and Management. Am Soc Clin Oncol Educ Book 2016:139-45. [PMID: 25993152 DOI: 10.14694/edbook_am.2015.35.139] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The 2005 discovery of the JAK2 mutation redefined the diagnosis and natural history of myeloproliferative neoplasms (MPNs). Most importantly, this improvement in the pathobiologic conceptualization has focused our evolution of this field from being defined as what it is not (e.g., Philadelphia [Ph]-negative) to what it is (e.g., JAK2-positive, CALR-positive) in the majority of MPN cases. In the ensuing 10 years, the field has experienced a paradigm shift in terms of understanding of the biologic basis of the development of MPNs, an explosion of knowledge of the genetics of MPNs, and has translated disease knowledge into effective targeted therapies. With greater uniformity and agreement on the diagnosis and differences among the individual MPNs, augmented by improved cytogenetic and molecular classification, attention has turned now to addressing the need for uniformity in risk stratification of patients in the clinic for both disease complications and disease transformation. This article will highlight the developments in the field with regard to risk stratification and prognostication in MPNs with focus on the clinical aspects of the patient who presents with either essential thrombocytosis (ET), polycythemia vera (PV), or myelofibrosis (MF).
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Affiliation(s)
- Naveen Pemmaraju
- From the Department of Medicine, The Johns Hopkins Hospital, Baltimore, MD; the Department of Leukemia, The University of Texas MD Anderson Cancer Center, Houston, TX
| | - Alison R Moliterno
- From the Department of Medicine, The Johns Hopkins Hospital, Baltimore, MD; the Department of Leukemia, The University of Texas MD Anderson Cancer Center, Houston, TX
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Abstract
PURPOSE OF REVIEW In the present review, we will define the preleukemic state. We aim at increasing awareness and research in the field of preleukemia that will nurture targeted therapy for the earlier steps of leukemia evolution. RECENT FINDINGS Emerging evidence supports the role of hematopoietic stem/progenitor cells carrying recurrent leukemia-related mutations as the cell of origin of both myeloid and lymphoid malignancies. The preleukemic stem cells can maintain at least to some extent their functionality; however, they have increased fitness endowed by the preleukemic mutations that lead to clonal expansion. SUMMARY The latent preleukemic period before overt leukemia presents can take years, and the majority of carriers will never develop leukemia in their lifetime. The preleukemic state is not rare, with greater than 1% of individuals having acquired one or more of the recognized preleukemic lesions. The high frequency of such abnormalities in the population may be the cost of growing old; however, another view could be that in order to survive to old age, the hematopoietic system must adapt to create robust hematopoietic stem/progenitor cells with an increased fitness and clonal expansion. Hence, leukemia does not necessarily start as a disease, but rather as a need, with the normally functioning preleukemic hematopoietic stem cells trying to maintain health for years but in time succumbing to their own acquired virtues.
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