1
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Gomez K. Advances in the diagnosis of heritable platelet disorders. Blood Rev 2022; 56:100972. [PMID: 35595614 DOI: 10.1016/j.blre.2022.100972] [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: 04/20/2022] [Revised: 05/09/2022] [Accepted: 05/10/2022] [Indexed: 11/02/2022]
Abstract
The last decade has seen large increases in the number of patients registered with heritable platelet disorders in national databases of bleeding disorders. Although individually rare, collectively they are a relatively common cause of heritable bleeding. This revolution has come about through the application of high-throughput sequencing strategies and efforts to standardize diagnostic testing. There is renewed interest in established parameters such as platelet volume and utilising simple tools such as blood smears. The diagnostic yield from peripheral blood smears can be improved with new microscopy techniques that could potentially assist in determining which patients need to be referred to tertiary centres for specialist testing. A better understanding of the other clinical features that can accompany abnormalities of platelet number or function, can lead to better clinical management and prevention of serious complications. There are challenges for clinicians who need to be aware of these developments, understand the limitations of new diagnostic techniques and keep abreast of strategies for incorporation into clinical practice. This review discusses some of these approaches, the limitations that clinicians need to be aware of and techniques that may enter clinical use in the future.
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Affiliation(s)
- Keith Gomez
- Haemophilia Centre and Thrombosis Unit, Royal Free London NHS Foundation Trust, London, UK.
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2
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Gomez K, Anderson J, Baker P, Biss T, Jennings I, Lowe G, Platton S. Clinical and laboratory diagnosis of heritable platelet disorders in adults and children: a British Society for Haematology Guideline. Br J Haematol 2021; 195:46-72. [PMID: 34435350 DOI: 10.1111/bjh.17690] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Keith Gomez
- Haemophilia Centre and Thrombosis Unit, Royal Free London NHS Foundation Trust, London
| | - Julia Anderson
- Haemophilia Thrombosis and Immunology Centre, Royal Infirmary, NHS Lothian, Edinburgh
| | - Peter Baker
- Haemophilia and Thrombosis Centre, Oxford University Hospitals NHS Foundation Trust, Oxford
| | - Tina Biss
- Haemophilia Comprehensive Care Centre, Royal Victoria Infirmary, Newcastle-upon-Tyne Hospitals NHS Foundation Trust, Newcastle-upon-Tyne
| | - Ian Jennings
- UK NEQAS for Blood Coagulation, Sheffield Teaching Hospitals NHS Foundation Trust, Sheffield
| | - Gillian Lowe
- Haemophilia Comprehensive Care Centre, Queen Elizabeth Hospital, University Hospitals Birmingham NHS Foundation Trust, Birmingham, UK
| | - Sean Platton
- Haemophilia Centre, The Royal London Hospital, Barts Health NHS Trust, London, UK
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3
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Inherited Platelet Disorders: An Updated Overview. Int J Mol Sci 2021; 22:ijms22094521. [PMID: 33926054 PMCID: PMC8123627 DOI: 10.3390/ijms22094521] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 04/17/2021] [Accepted: 04/21/2021] [Indexed: 02/06/2023] Open
Abstract
Platelets play a major role in hemostasis as ppwell as in many other physiological and pathological processes. Accordingly, production of about 1011 platelet per day as well as appropriate survival and functions are life essential events. Inherited platelet disorders (IPDs), affecting either platelet count or platelet functions, comprise a heterogenous group of about sixty rare diseases caused by molecular anomalies in many culprit genes. Their clinical relevance is highly variable according to the specific disease and even within the same type, ranging from almost negligible to life-threatening. Mucocutaneous bleeding diathesis (epistaxis, gum bleeding, purpura, menorrhagia), but also multisystemic disorders and/or malignancy comprise the clinical spectrum of IPDs. The early and accurate diagnosis of IPDs and a close patient medical follow-up is of great importance. A genotype-phenotype relationship in many IPDs makes a molecular diagnosis especially relevant to proper clinical management. Genetic diagnosis of IPDs has been greatly facilitated by the introduction of high throughput sequencing (HTS) techniques into mainstream investigation practice in these diseases. However, there are still unsolved ethical concerns on general genetic investigations. Patients should be informed and comprehend the potential implications of their genetic analysis. Unlike the progress in diagnosis, there have been no major advances in the clinical management of IPDs. Educational and preventive measures, few hemostatic drugs, platelet transfusions, thrombopoietin receptor agonists, and in life-threatening IPDs, allogeneic hematopoietic stem cell transplantation are therapeutic possibilities. Gene therapy may be a future option. Regular follow-up by a specialized hematology service with multidisciplinary support especially for syndromic IPDs is mandatory.
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4
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Gomez K. Genomic Analysis for the Detection of Bleeding and Thrombotic Disorders. Semin Thromb Hemost 2021; 47:174-182. [PMID: 33636748 DOI: 10.1055/s-0041-1722865] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The development of high-throughput sequencing technologies has ushered in a new era of genomic testing in clinical medicine. This has greatly enhanced our diagnostic repertoire for hemostatic diseases particularly for milder or rarer bleeding disorders. New genetic causes for heritable platelet disorders have been discovered along with the recognition of clinical manifestations outside hemostasis, such as the association of leukemia with RUNX1 variation. Genome-wide association studies in heritable thrombophilia have demonstrated that some of the genetic variants that are commonly included in thrombophilia testing are of no clinical relevance, while uncovering new variants that should potentially be included. The implementation of new technology has necessitated far-reaching changes in clinical practice to deal with incidental findings, variants of uncertain significance, and genetic disease modifiers. Mild bleeding disorders that were previously considered to have a monogenic basis now appear to have an oligogenic etiology. To harness these advances in knowledge large databases have been developed to capture the new genomic information with phenotypic features on a population-wide scale. The use of this so-called "big data" requires new bioinformatics tools with the promise of delivering precision medicine in the foreseeable future. This review discusses the use of these technologies in clinical practice, the benefits of genomic testing, and some of the challenges associated with implementation.
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Affiliation(s)
- Keith Gomez
- Haemophilia Centre and Thrombosis Unit, Royal Free London NHS Foundation Trust, London, United Kingdom
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5
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Al-Huniti A, Kahr WH. Inherited Platelet Disorders: Diagnosis and Management. Transfus Med Rev 2020; 34:277-285. [PMID: 33082057 DOI: 10.1016/j.tmrv.2020.09.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2020] [Revised: 09/09/2020] [Accepted: 09/10/2020] [Indexed: 12/22/2022]
Abstract
Inherited platelet disorders are rare but they can have considerable clinical impacts, and studies of their causes have advanced understanding of platelet formation and function. Effective hemostasis requires adequate circulating numbers of functional platelets. Quantitative, qualitative and combined platelet disorders with a bleeding phenotype have been linked to defects in platelet cytoskeletal elements, cell surface receptors, signal transduction pathways, secretory granules and other aspects. Inherited platelet disorders have variable clinical presentations, and diagnosis and management is often challenging. Evaluation begins with detailed patient and family histories, including a bleeding score. The physical exam identifies potential syndromic features of inherited platelet disorders and rules out other causes. Laboratory investigations include a complete blood count, blood film, coagulation testing and Von Willebrand factor assessment. A suspected platelet function disorder is further assessed by platelet aggregation, flow cytometry, platelet dense granule release and/or content, and genetic testing. The management of platelet function disorders aims to minimize the risk of bleeding and achieve adequate hemostasis when needed. Although not universal, platelet transfusion remains a crucial component in the management of many inherited platelet disorders.
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Affiliation(s)
- Ahmad Al-Huniti
- Division of Haematology/Oncology, Hospital for Sick Children, Toronto, ON, Canada
| | - Walter Ha Kahr
- Division of Haematology/Oncology, Hospital for Sick Children, Toronto, ON, Canada; Cell Biology Program, Research Institute, Hospital for Sick Children, Toronto, ON, Canada; Departments of Paediatrics and Biochemistry, University of Toronto, Toronto, ON, Canada.
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6
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Abstract
PURPOSE OF REVIEW The increasing use of high throughput sequencing and genomic analysis has facilitated the discovery of new causes of inherited platelet disorders. Studies of these disorders and their respective mouse models have been central to understanding their biology, and also in revealing new aspects of platelet function and production. This review covers recent contributions to the identification of genes, proteins and variants associated with inherited platelet defects, and highlights how these studies have provided insights into platelet development and function. RECENT FINDINGS Novel genes recently implicated in human platelet dysfunction include the galactose metabolism enzyme UDP-galactose-4-epimerase in macrothrombocytopenia, and erythropoietin-producing hepatoma-amplified sequence receptor transmembrane tyrosine kinase EPHB2 in a severe bleeding disorder with deficiencies in platelet agonist response and granule secretion. Recent studies of disease-associated variants established or clarified roles in platelet function and/or production for the membrane receptor G6b-B, the FYN-binding protein FYB1/ADAP, the RAS guanyl-releasing protein RASGRP2/CalDAG-GEFI and the receptor-like protein tyrosine phosphatase PTPRJ/CD148. Studies of genes associated with platelet disorders advanced understanding of the cellular roles of neurobeachin-like 2, as well as several genes influenced by the transcription regulator RUNT-related transcription factor 1 (RUNX1), including NOTCH4. SUMMARY The molecular bases of many hereditary platelet disorders have been elucidated by the application of recent advances in cell imaging and manipulation, genomics and protein function analysis. These techniques have also aided the detection of new disorders, and enabled studies of disease-associated genes and variants to enhance understanding of platelet development and function.
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7
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Blaauwgeers MW, Asten I, Kruip MJ, Beckers EA, Coppens M, Eikenboom J, Galen KP, Huisman A, Korporaal SJ, Ploos van Amstel HK, Tamminga RY, Urbanus RT, Schutgens RE. The limitation of genetic testing in diagnosing patients suspected for congenital platelet defects. Am J Hematol 2020; 95:E26-E28. [PMID: 31659778 PMCID: PMC6916199 DOI: 10.1002/ajh.25667] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 10/22/2019] [Accepted: 10/23/2019] [Indexed: 12/05/2022]
Affiliation(s)
- Maaike W. Blaauwgeers
- Van CreveldkliniekUniversity Medical Center Utrecht, University Utrecht Utrecht The Netherlands
| | - Ivar Asten
- Van CreveldkliniekUniversity Medical Center Utrecht, University Utrecht Utrecht The Netherlands
- Van Creveld LaboratoryUniversity Medical Center Utrecht, University Utrecht Utrecht The Netherlands
- Center for Circulatory Health, Department of Clinical Chemistry and HaematologyUniversity Medical Center Utrecht, University Utrecht Utrecht The Netherlands
| | - Marieke J.H.A. Kruip
- Department of HaematologyErasmus University Medical Center Rotterdam The Netherlands
| | - Erik A.M. Beckers
- Department of HematologyMaastricht University Medical Center Maastricht The Netherlands
| | - Michiel Coppens
- Department of Vascular Medicine, Amsterdam Cardiovascular SciencesAmsterdam University Medical Center, location AMC Amsterdam The Netherlands
| | - Jeroen Eikenboom
- Department of Internal Medicine, division of Thrombosis and HaemostasisLeiden University Medical Center Leiden The Netherlands
| | - Karin P.M. Galen
- Van CreveldkliniekUniversity Medical Center Utrecht, University Utrecht Utrecht The Netherlands
| | - Albert Huisman
- Center for Circulatory Health, Department of Clinical Chemistry and HaematologyUniversity Medical Center Utrecht, University Utrecht Utrecht The Netherlands
| | - Suzanne J.A. Korporaal
- Center for Circulatory Health, Department of Clinical Chemistry and HaematologyUniversity Medical Center Utrecht, University Utrecht Utrecht The Netherlands
- Laboratory of Experimental CardiologyUniversity Medical Center Utrecht, University Utrecht Utrecht The Netherlands
| | | | - Rienk Y.J. Tamminga
- Department of Pediatric HematologyBeatrix Children's Hospital, University Medical Center Groningen Groningen The Netherlands
| | - Rolf T. Urbanus
- Van CreveldkliniekUniversity Medical Center Utrecht, University Utrecht Utrecht The Netherlands
- Van Creveld LaboratoryUniversity Medical Center Utrecht, University Utrecht Utrecht The Netherlands
| | - Roger E.G. Schutgens
- Van CreveldkliniekUniversity Medical Center Utrecht, University Utrecht Utrecht The Netherlands
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8
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Gomez K. New information on rare diseases ‐ how important is that for us? Br J Haematol 2019; 185:819-820. [DOI: 10.1111/bjh.15833] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Keith Gomez
- Katherine Dormandy Haemophilia Centre and Thrombosis Unit Royal Free London NHS Foundation Trust London UK
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9
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Gorski MM, Lecchi A, Femia EA, La Marca S, Cairo A, Pappalardo E, Lotta LA, Artoni A, Peyvandi F. Complications of whole-exome sequencing for causal gene discovery in primary platelet secretion defects. Haematologica 2019; 104:2084-2090. [PMID: 30819905 PMCID: PMC6886420 DOI: 10.3324/haematol.2018.204990] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Accepted: 02/22/2019] [Indexed: 01/24/2023] Open
Abstract
Primary platelet secretion defects constitute a heterogeneous group of functional defects characterized by reduced platelet granule secretion upon stimulation by different agonists. The clinical and laboratory heterogeneity of primary platelet secretion defects warrants a tailored approach. We performed a pilot study in order to develop DNA sequence analysis pipelines for gene discovery and to create a list of candidate causal genes for platelet secretion defects. Whole-exome sequencing analysis of 14 unrelated Italian patients with primary secretion defects and 16 controls was performed on Illumina HiSeq. Variant prioritization was carried out using two filtering approaches: identification of rare, potentially damaging variants in platelet candidate genes or by selecting singletons. To corroborate the results, exome sequencing was applied in a family in which platelet secretion defects and a bleeding diathesis were present. Platelet candidate gene analysis revealed gene defects in 10/14 patients, which included ADRA2A, ARHGAP1, DIAPH1, EXOC1, FCGR2A, ITPR1, LTBP1, PTPN7, PTPN12, PRKACG, PRKCD, RAP1GAP, STXBP5L, and VWF. The analysis of singletons identified additional gene defects in PLG and PHACTR2 in two other patients. The family analysis confirmed a missense variant p.D1144N in the STXBP5L gene and p.P83H in the KCNMB3 gene as potentially causal. In summary, exome sequencing revealed potential causal variants in 12 of 14 patients with primary platelet secretion defects, highlighting the limitations of the genomic approaches for causal gene identification in this heterogeneous clinical and laboratory phenotype.
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Affiliation(s)
- Marcin M Gorski
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Angelo Bianchi Bonomi Hemophilia and Thrombosis Center, Milan.,Università degli Studi di Milano, Department of Pathophysiology and Transplantation and Fondazione Luigi Villa, Milan, Italy
| | - Anna Lecchi
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Angelo Bianchi Bonomi Hemophilia and Thrombosis Center, Milan
| | - Eti A Femia
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Angelo Bianchi Bonomi Hemophilia and Thrombosis Center, Milan
| | - Silvia La Marca
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Angelo Bianchi Bonomi Hemophilia and Thrombosis Center, Milan
| | - Andrea Cairo
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Angelo Bianchi Bonomi Hemophilia and Thrombosis Center, Milan
| | - Emanuela Pappalardo
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Angelo Bianchi Bonomi Hemophilia and Thrombosis Center, Milan.,Università degli Studi di Milano, Department of Pathophysiology and Transplantation and Fondazione Luigi Villa, Milan, Italy
| | - Luca A Lotta
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Angelo Bianchi Bonomi Hemophilia and Thrombosis Center, Milan
| | - Andrea Artoni
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Angelo Bianchi Bonomi Hemophilia and Thrombosis Center, Milan
| | - Flora Peyvandi
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Angelo Bianchi Bonomi Hemophilia and Thrombosis Center, Milan .,Università degli Studi di Milano, Department of Pathophysiology and Transplantation and Fondazione Luigi Villa, Milan, Italy
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10
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Andres O, König EM, Althaus K, Bakchoul T, Bugert P, Eber S, Knöfler R, Kunstmann E, Manukjan G, Meyer O, Strauß G, Streif W, Thiele T, Wiegering V, Klopocki E, Schulze H. Use of Targeted High-Throughput Sequencing for Genetic Classification of Patients with Bleeding Diathesis and Suspected Platelet Disorder. TH OPEN 2018; 2:e445-e454. [PMID: 31249973 PMCID: PMC6524924 DOI: 10.1055/s-0038-1676813] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Accepted: 11/19/2018] [Indexed: 02/07/2023] Open
Abstract
Inherited platelet disorders (IPD) form a rare and heterogeneous disease entity that is present in about 8% of patients with non-acquired bleeding diathesis. Identification of the defective cellular pathway is an important criterion for stratifying the patient's individual risk profile and for choosing personalized therapeutic options. While costs of high-throughput sequencing technologies have rapidly declined over the last decade, molecular genetic diagnosis of bleeding and platelet disorders is getting more and more suitable within the diagnostic algorithms. In this study, we developed, verified, and evaluated a targeted, panel-based next-generation sequencing approach comprising 59 genes associated with IPD for a cohort of 38 patients with a history of recurrent bleeding episodes and functionally suspected, but so far genetically undefined IPD. DNA samples from five patients with genetically defined IPD with disease-causing variants in
WAS
,
RBM8A
,
FERMT3
,
P2YR12
, and
MYH9
served as controls during the validation process. In 40% of 35 patients analyzed, we were able to finally detect 15 variants, eight of which were novel, in 11 genes,
ACTN1
,
AP3B1
,
GFI1B
,
HPS1
,
HPS4
,
HPS6
,
MPL
,
MYH9
,
TBXA2R
,
TPM4
, and
TUBB1
, and classified them according to current guidelines. Apart from seven variants of uncertain significance in 11% of patients, nine variants were classified as likely pathogenic or pathogenic providing a molecular diagnosis for 26% of patients. This report also emphasizes on potentials and pitfalls of this tool and prospectively proposes its rational implementation within the diagnostic algorithms of IPD.
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Affiliation(s)
- Oliver Andres
- University Children's Hospital, University of Würzburg, Würzburg, Germany
| | - Eva-Maria König
- Institute of Human Genetics, University of Würzburg, Würzburg, Germany
| | - Karina Althaus
- Centre for Clinical Transfusion Medicine, University Hospital of Tübingen, Tübingen, Germany.,Institute for Transfusion Medicine, University of Greifswald, Greifswald, Germany
| | - Tamam Bakchoul
- Centre for Clinical Transfusion Medicine, University Hospital of Tübingen, Tübingen, Germany.,Institute for Transfusion Medicine, University of Greifswald, Greifswald, Germany
| | - Peter Bugert
- DRK-Blutspendedienst Baden-Württemberg-Hessen, Institute for Transfusion Medicine and Immunology, Heidelberg University, Mannheim, Germany
| | - Stefan Eber
- University Children's Hospital, Technical University Munich, Munich, Germany
| | - Ralf Knöfler
- Department of Pediatrics, Carl Gustav Carus University Hospital, Dresden, Germany
| | - Erdmute Kunstmann
- Institute of Human Genetics, University of Würzburg, Würzburg, Germany
| | - Georgi Manukjan
- Institute of Experimental Biomedicine, University Hospital Würzburg, Würzburg, Germany
| | - Oliver Meyer
- Institute for Transfusion Medicine, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Gabriele Strauß
- Department for Pediatric Oncology and Hematology, HELIOS Klinikum Berlin-Buch, Berlin, Germany
| | - Werner Streif
- Department of Pediatrics, Medical University Innsbruck, Innsbruck, Austria
| | - Thomas Thiele
- Institute for Transfusion Medicine, University of Greifswald, Greifswald, Germany
| | - Verena Wiegering
- University Children's Hospital, University of Würzburg, Würzburg, Germany
| | - Eva Klopocki
- Institute of Human Genetics, University of Würzburg, Würzburg, Germany
| | - Harald Schulze
- Institute of Experimental Biomedicine, University Hospital Würzburg, Würzburg, Germany
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11
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Swinkels M, Rijkers M, Voorberg J, Vidarsson G, Leebeek FWG, Jansen AJG. Emerging Concepts in Immune Thrombocytopenia. Front Immunol 2018; 9:880. [PMID: 29760702 PMCID: PMC5937051 DOI: 10.3389/fimmu.2018.00880] [Citation(s) in RCA: 130] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Accepted: 04/09/2018] [Indexed: 01/19/2023] Open
Abstract
Immune thrombocytopenia (ITP) is an autoimmune disease defined by low platelet counts which presents with an increased bleeding risk. Several genetic risk factors (e.g., polymorphisms in immunity-related genes) predispose to ITP. Autoantibodies and cytotoxic CD8+ T cells (Tc) mediate the anti-platelet response leading to thrombocytopenia. Both effector arms enhance platelet clearance through phagocytosis by splenic macrophages or dendritic cells and by induction of apoptosis. Meanwhile, platelet production is inhibited by CD8+ Tc targeting megakaryocytes in the bone marrow. CD4+ T helper cells are important for B cell differentiation into autoantibody secreting plasma cells. Regulatory Tc are essential to secure immune tolerance, and reduced levels have been implicated in the development of ITP. Both Fcγ-receptor-dependent and -independent pathways are involved in the etiology of ITP. In this review, we present a simplified model for the pathogenesis of ITP, in which exposure of platelet surface antigens and a loss of tolerance are required for development of chronic anti-platelet responses. We also suggest that infections may comprise an important trigger for the development of auto-immunity against platelets in ITP. Post-translational modification of autoantigens has been firmly implicated in the development of autoimmune disorders like rheumatoid arthritis and type 1 diabetes. Based on these findings, we propose that post-translational modifications of platelet antigens may also contribute to the pathogenesis of ITP.
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Affiliation(s)
- Maurice Swinkels
- Department of Hematology, Erasmus University Medical Centre, Rotterdam, Netherlands
| | - Maaike Rijkers
- Department of Plasma Proteins, AMC-Sanquin Landsteiner Laboratory, Amsterdam, Netherlands
| | - Jan Voorberg
- Department of Plasma Proteins, AMC-Sanquin Landsteiner Laboratory, Amsterdam, Netherlands
| | - Gestur Vidarsson
- Department of Experimental Immunohematology, AMC-Sanquin Landsteiner Laboratory, Amsterdam, Netherlands
| | - Frank W G Leebeek
- Department of Hematology, Erasmus University Medical Centre, Rotterdam, Netherlands
| | - A J Gerard Jansen
- Department of Hematology, Erasmus University Medical Centre, Rotterdam, Netherlands.,Department of Plasma Proteins, AMC-Sanquin Landsteiner Laboratory, Amsterdam, Netherlands
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12
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Nbeal2 interacts with Dock7, Sec16a, and Vac14. Blood 2017; 131:1000-1011. [PMID: 29187380 DOI: 10.1182/blood-2017-08-800359] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Accepted: 11/21/2017] [Indexed: 12/11/2022] Open
Abstract
Mutations in NBEAL2, the gene encoding the scaffolding protein Nbeal2, are causal of gray platelet syndrome (GPS), a rare recessive bleeding disorder characterized by platelets lacking α-granules and progressive marrow fibrosis. We present here the interactome of Nbeal2 with additional validation by reverse immunoprecipitation of Dock7, Sec16a, and Vac14 as interactors of Nbeal2. We show that GPS-causing mutations in its BEACH domain have profound and possible effects on the interaction with Dock7 and Vac14, respectively. Proximity ligation assays show that these 2 proteins are physically proximal to Nbeal2 in human megakaryocytes. In addition, we demonstrate that Nbeal2 is primarily localized in the cytoplasm and Dock7 on the membrane of or in α-granules. Interestingly, platelets from GPS cases and Nbeal2-/- mice are almost devoid of Dock7, resulting in a profound dysregulation of its signaling pathway, leading to defective actin polymerization, platelet activation, and shape change. This study shows for the first time proteins interacting with Nbeal2 and points to the dysregulation of the canonical signaling pathway of Dock7 as a possible cause of the aberrant formation of platelets in GPS cases and Nbeal2-deficient mice.
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13
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Nava T, Rivard GE, Bonnefoy A. Challenges on the diagnostic approach of inherited platelet function disorders: Is a paradigm change necessary? Platelets 2017; 29:148-155. [PMID: 29090587 DOI: 10.1080/09537104.2017.1356918] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Inherited platelet function disorders (IPFD) have been assessed for more than 50 years by aggregation- and secretion-based tests. Several decision trees are available intending to standardize the investigation of IPFD. A large variability of approaches is still in use among the laboratories across the world. In spite of costly and lengthy laboratory evaluation, the results have been found inconclusive or negative in a significant part of patients having bleeding manifestations. Molecular investigation of newly identified IPFD has recently contributed to a better understanding of the complexity of platelet function. Once considered "classic" IPFDs, Glanzmann thrombasthenia and Bernard-Soulier syndrome have each had their pathophysiology reassessed and their diagnosis made more precise and informative. Megakaryopoiesis, platelet formation, and function have been found tightly interlinked, with several genes being involved in both inherited thrombocytopenias and impaired platelet function. Moreover, genetic approaches have moved from being used as confirmatory diagnostic tests to being tools for identification of genetic variants associated with bleeding disorders, even in the absence of a clear phenotype in functional testing. In this study, we aim to address some limits of the conventional tests used for the diagnosis of IPFD, and to highlight the potential contribution of recent molecular tools and opportunities to rethink the way we should approach the investigation of IPFD.
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Affiliation(s)
- Tiago Nava
- a Centre Hospitalier Universitaire Sainte-Justine , Hematology and Oncology Division , Montréal , QC , Canada.,b Child and Adolescent Health, School of Medicine , Universidade Federal do Rio Grande do Sul (UFRGS) , Porto Alegre , Brazil
| | - Georges-Etienne Rivard
- a Centre Hospitalier Universitaire Sainte-Justine , Hematology and Oncology Division , Montréal , QC , Canada
| | - Arnaud Bonnefoy
- a Centre Hospitalier Universitaire Sainte-Justine , Hematology and Oncology Division , Montréal , QC , Canada
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14
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Leinøe E, Zetterberg E, Kinalis S, Østrup O, Kampmann P, Norström E, Andersson N, Klintman J, Qvortrup K, Nielsen FC, Rossing M. Application of whole-exome sequencing to direct the specific functional testing and diagnosis of rare inherited bleeding disorders in patients from the Öresund Region, Scandinavia. Br J Haematol 2017; 179:308-322. [PMID: 28748566 PMCID: PMC5655919 DOI: 10.1111/bjh.14863] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Accepted: 06/20/2017] [Indexed: 01/19/2023]
Abstract
Rare inherited bleeding disorders (IBD) are a common cause of bleeding tendency. To ensure a correct diagnosis, specialized laboratory analyses are necessary. This study reports the results of an upfront diagnostic strategy using targeted whole exome sequencing. In total, 156 patients with a significant bleeding assessment tool score participated in the study, of which a third had thrombocytopenia. Eighty‐seven genes specifically associated with genetic predisposition to bleeding were analysed by whole exome sequencing. Variants were classified according to the five‐tier scheme. We identified 353 germline variants. Eight patients (5%) harboured a known pathogenic variant. Of the 345 previously unknown variants, computational analyses predicted 99 to be significant. Further filtration according to the Mendelian inheritance pattern, resulted in 59 variants being predicted to be clinically significant. Moreover, 34% (20/59) were assigned as novel class 4 or 5 variants upon targeted functional testing. A class 4 or 5 variant was identified in 30% of patients with thrombocytopenia (14/47) versus 11% of patients with a normal platelet count (12/109) (P < 0·01). An IBD diagnosis has a major clinical impact. The genetic investigations detailed here extricated our patients from a diagnostic conundrum, thus demonstrating that continuous optimization of the diagnostic work‐up of IBD is of great benefit.
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Affiliation(s)
- Eva Leinøe
- Department of Haematology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Eva Zetterberg
- Department of Haematology, Coagulation Unit, Skaane University Hospital, Lund, Sweden
| | - Savvas Kinalis
- Centre for Genomic Medicine, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Olga Østrup
- Centre for Genomic Medicine, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Peter Kampmann
- Department of Haematology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Eva Norström
- Department of Translational Medicine, Lund University, Skaane University Hospital, Lund, Sweden
| | - Nadine Andersson
- Department of Haematology, Coagulation Unit, Skaane University Hospital, Lund, Sweden
| | - Jenny Klintman
- Department of Haematology, Coagulation Unit, Skaane University Hospital, Lund, Sweden
| | - Klaus Qvortrup
- Department of Biomedical Sciences, Core Facility for Integrated Microscopy (CFIM), University of Copenhagen, Copenhagen, Denmark
| | - Finn Cilius Nielsen
- Centre for Genomic Medicine, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Maria Rossing
- Centre for Genomic Medicine, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
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Sivapalaratnam S, Collins J, Gomez K. Diagnosis of inherited bleeding disorders in the genomic era. Br J Haematol 2017; 179:363-376. [PMID: 28612396 DOI: 10.1111/bjh.14796] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Inherited bleeding disorders affect between 1 in 1000 individuals for the most common disorder, von Willebrand Disease, to only 8 reported cases worldwide of alpha-2-antiplasmin deficiency. Those with an identifiable abnormality can be divided into disorders of coagulation factors (87%), platelet count and function (8%) and the fibrinolytic system (3%). Of the patients registered in the UK with a bleeding disorder, the remaining 2% are unclassifiable. In addition to bleeding symptoms, patients with an inherited bleeding disorder can manifest other abnormalities, making an accurate and complete diagnosis that reflects the underlying molecular pathology important. Although some inherited bleeding disorders can still be easily diagnosed through a combination of careful clinical assessment and laboratory assays of varying degrees of complexity, there are many where conventional approaches are inadequate. Improvements in phenotyping assays have enhanced our diagnostic armoury but genotyping now offers the most accurate and complete diagnosis for some of these conditions. The advent of next generation sequencing technology has meant that many genes can now be analysed routinely in clinical practice. Here, we discuss the different diagnostic tools currently available for inherited bleeding disorders and suggest that genotyping should be incorporated at an early stage in the diagnostic pathway.
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Affiliation(s)
- Suthesh Sivapalaratnam
- Department of Haematology, University of Cambridge, Cambridge, UK.,The Royal London Haemophilia Centre, The Royal London Hospital, London, UK
| | - Janine Collins
- Department of Haematology, University of Cambridge, Cambridge, UK.,The Royal London Haemophilia Centre, The Royal London Hospital, London, UK
| | - Keith Gomez
- Katherine Dormandy Haemophilia Centre and Thrombosis Unit, Royal Free London NHS Foundation Trust, London, UK
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