1
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Montague SJ, Price J, Pennycott K, Pavey NJ, Martin EM, Thirlwell I, Kemble S, Monteiro C, Redmond-Motteram L, Lawson N, Reynolds K, Fratter C, Bignell P, Groenheide A, Huskens D, de Laat B, Pike JA, Poulter NS, Thomas SG, Lowe GC, Lancashire J, Harrison P, Morgan NV. Comprehensive functional characterization of a novel ANO6 variant in a new patient with Scott syndrome. J Thromb Haemost 2024; 22:2281-2293. [PMID: 38492852 DOI: 10.1016/j.jtha.2024.02.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Revised: 02/09/2024] [Accepted: 02/29/2024] [Indexed: 03/18/2024]
Abstract
BACKGROUND Scott syndrome is a mild platelet-type bleeding disorder, first described in 1979, with only 3 unrelated families identified through defective phosphatidylserine (PS) exposure and confirmed by sequencing. The syndrome is distinguished by impaired surface exposure of procoagulant PS on platelets after stimulation. To date, platelet function and thrombin generation in this condition have not been extensively characterized. OBJECTIVES Genetic and functional studies were undertaken in a consanguineous family with a history of excessive bleeding of unknown cause. METHODS A targeted gene panel of known bleeding and platelet genes was used to identify possible genetic variants. Platelet phenotyping, flow adhesion, flow cytometry, whole blood and platelet-rich plasma thrombin generation, and specialized extracellular vesicle measurements were performed. RESULTS We detected a novel homozygous frameshift variant, c.1943del (p.Arg648Hisfs∗23), in ANO6 encoding Anoctamin 6, in a patient with a bleeding history but interestingly with normal ANO6 expression. Phenotyping of the patient's platelets confirmed the absence of PS expression and procoagulant activity but also revealed other defects including reduced platelet δ granules, reduced ristocetin-mediated aggregation and secretion, and reduced P-selectin expression after stimulation. PS was absent on spread platelets, and thrombi formed over collagen at 1500/s. Reduced thrombin generation was observed in platelet-rich plasma and confirmed in whole blood using a new thrombin generation assay. CONCLUSION We present a comprehensive report of a patient with Scott syndrome with a novel frameshift variant in AN06, which is associated with no platelet PS exposure and markedly reduced thrombin generation in whole blood, explaining the significant bleeding phenotype observed.
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Affiliation(s)
- Samantha J Montague
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Joshua Price
- Institute of Inflammation and Ageing, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Katherine Pennycott
- Institute of Inflammation and Ageing, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Natasha J Pavey
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Eleyna M Martin
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Isaac Thirlwell
- Institute of Inflammation and Ageing, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Samuel Kemble
- Institute of Inflammation and Ageing, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Catarina Monteiro
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Lily Redmond-Motteram
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Natalie Lawson
- Haemophilia Unit, Birmingham Children's Hospital, Birmingham Women's and Children's NHS Foundation Trust, Birmingham, United Kingdom
| | - Katherine Reynolds
- Haemophilia Unit, Birmingham Children's Hospital, Birmingham Women's and Children's NHS Foundation Trust, Birmingham, United Kingdom
| | - Carl Fratter
- Oxford Genetics Laboratories, Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom
| | - Patricia Bignell
- Oxford Genetics Laboratories, Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom
| | | | - Dana Huskens
- Synapse Research Institute, Maastricht, the Netherlands
| | - Bas de Laat
- Synapse Research Institute, Maastricht, the Netherlands
| | - Jeremy A Pike
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom; Centre of Membrane Proteins and Receptors, Universities of Birmingham and Nottingham, the Midlands, United Kingdom
| | - Natalie S Poulter
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom; Centre of Membrane Proteins and Receptors, Universities of Birmingham and Nottingham, the Midlands, United Kingdom
| | - Steven G Thomas
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom; Centre of Membrane Proteins and Receptors, Universities of Birmingham and Nottingham, the Midlands, United Kingdom
| | - Gillian C Lowe
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom; Comprehensive Care Haemophilia Centre, University Hospital Birmingham NHS Foundation Trust, Birmingham, United Kingdom
| | - Jonathan Lancashire
- Haemophilia Unit, Birmingham Children's Hospital, Birmingham Women's and Children's NHS Foundation Trust, Birmingham, United Kingdom
| | - Paul Harrison
- Institute of Inflammation and Ageing, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Neil V Morgan
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom.
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2
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Barrachina MN, Pernes G, Becker IC, Allaeys I, Hirsch TI, Groeneveld DJ, Khan AO, Freire D, Guo K, Carminita E, Morgan PK, Collins TJC, Mellett NA, Wei Z, Almazni I, Italiano JE, Luyendyk J, Meikle PJ, Puder M, Morgan NV, Boilard E, Murphy AJ, Machlus KR. Efficient megakaryopoiesis and platelet production require phospholipid remodeling and PUFA uptake through CD36. NATURE CARDIOVASCULAR RESEARCH 2023; 2:746-763. [PMID: 39195958 DOI: 10.1038/s44161-023-00305-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Accepted: 06/21/2023] [Indexed: 08/29/2024]
Abstract
Lipids contribute to hematopoiesis and membrane properties and dynamics; however, little is known about the role of lipids in megakaryopoiesis. Here we show that megakaryocyte progenitors, megakaryocytes and platelets present a unique lipidome progressively enriched in polyunsaturated fatty acid (PUFA)-containing phospholipids. In vitro, inhibition of both exogenous fatty acid functionalization and uptake as well as de novo lipogenesis impaired megakaryocyte differentiation and proplatelet production. In vivo, mice on a high saturated fatty acid diet had significantly lower platelet counts, which was prevented by eating a PUFA-enriched diet. Fatty acid uptake was largely dependent on CD36, and its deletion in mice resulted in low platelets. Moreover, patients with a CD36 loss-of-function mutation exhibited thrombocytopenia and increased bleeding. Our results suggest that fatty acid uptake and regulation is essential for megakaryocyte maturation and platelet production and that changes in dietary fatty acids may be a viable target to modulate platelet counts.
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Affiliation(s)
- Maria N Barrachina
- Vascular Biology Program, Boston Children's Hospital, Boston, MA, USA
- Harvard Medical School, Department of Surgery, Boston Children's Hospital, Boston, MA, USA
| | - Gerard Pernes
- Haematopoiesis and Leukocyte Biology, Baker Heart and Diabetes Institute, Melbourne, VIC, Australia
| | - Isabelle C Becker
- Vascular Biology Program, Boston Children's Hospital, Boston, MA, USA
- Harvard Medical School, Department of Surgery, Boston Children's Hospital, Boston, MA, USA
| | - Isabelle Allaeys
- Centre de Recherche du CHU de Québec-Université Laval and Centre de Recherche ARThrite, Québec, QC, Canada
| | - Thomas I Hirsch
- Vascular Biology Program, Boston Children's Hospital, Boston, MA, USA
- Harvard Medical School, Department of Surgery, Boston Children's Hospital, Boston, MA, USA
| | - Dafna J Groeneveld
- Department of Pathobiology and Diagnostic Investigation, Michigan State University, East Lansing, MI, USA
| | - Abdullah O Khan
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
- MRC Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine and National Institute for Health Research (NIHR) Oxford Biomedical Research Centre, University of Oxford, Oxford, UK
| | - Daniela Freire
- Vascular Biology Program, Boston Children's Hospital, Boston, MA, USA
| | - Karen Guo
- Vascular Biology Program, Boston Children's Hospital, Boston, MA, USA
| | - Estelle Carminita
- Vascular Biology Program, Boston Children's Hospital, Boston, MA, USA
- Harvard Medical School, Department of Surgery, Boston Children's Hospital, Boston, MA, USA
| | - Pooranee K Morgan
- Haematopoiesis and Leukocyte Biology, Baker Heart and Diabetes Institute, Melbourne, VIC, Australia
| | - Thomas J C Collins
- Haematopoiesis and Leukocyte Biology, Baker Heart and Diabetes Institute, Melbourne, VIC, Australia
| | - Natalie A Mellett
- Metabolomics, Baker Heart and Diabetes Institute, Melbourne, VIC, Australia
| | - Zimu Wei
- Department of Pathobiology and Diagnostic Investigation, Michigan State University, East Lansing, MI, USA
| | - Ibrahim Almazni
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
| | - Joseph E Italiano
- Vascular Biology Program, Boston Children's Hospital, Boston, MA, USA
- Harvard Medical School, Department of Surgery, Boston Children's Hospital, Boston, MA, USA
| | - James Luyendyk
- Department of Pathobiology and Diagnostic Investigation, Michigan State University, East Lansing, MI, USA
| | - Peter J Meikle
- Metabolomics, Baker Heart and Diabetes Institute, Melbourne, VIC, Australia
| | - Mark Puder
- Vascular Biology Program, Boston Children's Hospital, Boston, MA, USA
- Harvard Medical School, Department of Surgery, Boston Children's Hospital, Boston, MA, USA
| | - Neil V Morgan
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
| | - Eric Boilard
- Centre de Recherche du CHU de Québec-Université Laval and Centre de Recherche ARThrite, Québec, QC, Canada
| | - Andrew J Murphy
- Haematopoiesis and Leukocyte Biology, Baker Heart and Diabetes Institute, Melbourne, VIC, Australia
| | - Kellie R Machlus
- Vascular Biology Program, Boston Children's Hospital, Boston, MA, USA.
- Harvard Medical School, Department of Surgery, Boston Children's Hospital, Boston, MA, USA.
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3
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Marconi C, Pecci A, Palombo F, Melazzini F, Bottega R, Nardi E, Bozzi V, Faleschini M, Barozzi S, Giangregorio T, Magini P, Balduini CL, Savoia A, Seri M, Noris P, Pippucci T. Exome sequencing in 116 patients with inherited thrombocytopenia that remained of unknown origin after systematic phenotype-driven diagnostic workup. Haematologica 2023; 108:1909-1919. [PMID: 36519321 PMCID: PMC10316235 DOI: 10.3324/haematol.2022.280993] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Accepted: 08/29/2022] [Indexed: 11/01/2023] Open
Abstract
Inherited thrombocytopenias (IT) are genetic diseases characterized by low platelet count, sometimes associated with congenital defects or a predisposition to develop additional conditions. Next-generation sequencing has substantially improved our knowledge of IT, with more than 40 genes identified so far, but obtaining a molecular diagnosis remains a challenge especially for patients with non-syndromic forms, having no clinical or functional phenotypes that raise suspicion about specific genes. We performed exome sequencing (ES) in a cohort of 116 IT patients (89 families), still undiagnosed after a previously validated phenotype-driven diagnostic algorithm including a targeted analysis of suspected genes. ES achieved a diagnostic yield of 36%, with a gain of 16% over the diagnostic algorithm. This can be explained by genetic heterogeneity and unspecific genotype-phenotype relationships that make the simultaneous analysis of all the genes, enabled by ES, the most reasonable strategy. Furthermore, ES disentangled situations that had been puzzling because of atypical inheritance, sex-related effects or false negative laboratory results. Finally, ES-based copy number variant analysis disclosed an unexpectedly high prevalence of RUNX1 deletions, predisposing to hematologic malignancies. Our findings demonstrate that ES, including copy number variant analysis, can substantially contribute to the diagnosis of IT and can solve diagnostic problems that would otherwise remain a challenge.
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Affiliation(s)
- Caterina Marconi
- Department of Medical and Surgical Science, University of Bologna, Bologna
| | - Alessandro Pecci
- Department of Internal Medicine, University of Pavia, Pavia, Italy; Medicina Generale 1, IRCCS Policlinico San Matteo Foundation, Pavia
| | - Flavia Palombo
- Department of Medical and Surgical Science, University of Bologna, Bologna
| | - Federica Melazzini
- Department of Internal Medicine, University of Pavia, Pavia, Italy; Medicina Generale 1, IRCCS Policlinico San Matteo Foundation, Pavia
| | - Roberta Bottega
- Institute for Maternal and Child Health - IRCCS Burlo Garofolo, Trieste
| | - Elena Nardi
- Department of Experimental, Diagnostic and Specialty Medicine, University of Bologna, Bologna
| | - Valeria Bozzi
- Medicina Generale 1, IRCCS Policlinico San Matteo Foundation, Pavia
| | | | - Serena Barozzi
- Medicina Generale 1, IRCCS Policlinico San Matteo Foundation, Pavia
| | | | - Pamela Magini
- Medical Genetics Unit, IRCCS Azienda Ospedaliero Universitaria di Bologna, Policlinico di Sant'Orsola, Bologna
| | | | - Anna Savoia
- Institute for Maternal and Child Health - IRCCS Burlo Garofolo, Trieste, Italy; Department of Medical Sciences, University of Trieste, Trieste
| | - Marco Seri
- Department of Medical and Surgical Science, University of Bologna, Bologna, Italy; Medical Genetics Unit, IRCCS Azienda Ospedaliero Universitaria di Bologna, Policlinico di Sant'Orsola, Bologna.
| | - Patrizia Noris
- Department of Internal Medicine, University of Pavia, Pavia, Italy; Medicina Generale 1, IRCCS Policlinico San Matteo Foundation, Pavia
| | - Tommaso Pippucci
- Medical Genetics Unit, IRCCS Azienda Ospedaliero Universitaria di Bologna, Policlinico di Sant'Orsola, Bologna
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4
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Pruthi RK. Testing strategies used in the diagnosis of rare inherited bleeding disorders. Expert Rev Hematol 2023:1-15. [PMID: 37144355 DOI: 10.1080/17474086.2023.2211257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
INTRODUCTION Rare Bleeding Disorders have a low population prevalence and may not be recognized by most clinicians. In addition, knowledge gaps of the indicated laboratory tests and their availability add to the potential for delayed diagnosis or misdiagnosis. The lack of widely available commercial, regulatory body approved esoteric tests limit them to reference laboratories, thus limiting easy access for patients. AREAS COVERED A literature search of Pubmed, Medline, Embase and review of international society guidelines was performed. Additional references from published articles were reviewed. A patient-centered approach to recognition and evaluation of RBD is discussed. EXPERT OPINION Recognition of RBD relies on obtaining a detailed patient personal and family hemostatic history. Inquiry into a history of involvement of other organ systems is important and if present should lead to suspicion of an inherited platelet disorder or a variant of Ehlers Danlos Syndrome. Multiple factors contribute to the complexity of development of efficient algorithms for diagnostic testing. Limitations in diagnostic sensitivity and specificity of screening tests, diagnostic tests, and esoteric tests further compound the complexity of establishing a diagnosis. Educational efforts focusing on clinician awareness of RBDs and available testing options are vital for optimal management of such patients.
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Affiliation(s)
- Rajiv K Pruthi
- Mayo Comprehensive Hemophilia Center, Division of Hematology, Department of Internal Medicine, Mayo Clinic College of Medicine, Rochester, MN, USA
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5
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Barrachina MN, Pernes G, Becker IC, Allaeys I, Hirsch TI, Groeneveld DJ, Khan AO, Freire D, Guo K, Carminita E, Morgan PK, Collins TJ, Mellett NA, Wei Z, Almazni I, Italiano JE, Luyendyk J, Meikle PJ, Puder M, Morgan NV, Boilard E, Murphy AJ, Machlus KR. Efficient megakaryopoiesis and platelet production require phospholipid remodeling and PUFA uptake through CD36. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.12.527706. [PMID: 36798332 PMCID: PMC9934665 DOI: 10.1101/2023.02.12.527706] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
Lipids contribute to hematopoiesis and membrane properties and dynamics, however, little is known about the role of lipids in megakaryopoiesis. Here, a lipidomic analysis of megakaryocyte progenitors, megakaryocytes, and platelets revealed a unique lipidome progressively enriched in polyunsaturated fatty acid (PUFA)-containing phospholipids. In vitro, inhibition of both exogenous fatty acid functionalization and uptake and de novo lipogenesis impaired megakaryocyte differentiation and proplatelet production. In vivo, mice on a high saturated fatty acid diet had significantly lower platelet counts, which was prevented by eating a PUFA-enriched diet. Fatty acid uptake was largely dependent on CD36, and its deletion in mice resulted in thrombocytopenia. Moreover, patients with a CD36 loss-of-function mutation exhibited thrombocytopenia and increased bleeding. Our results suggest that fatty acid uptake and regulation is essential for megakaryocyte maturation and platelet production, and that changes in dietary fatty acids may be a novel and viable target to modulate platelet counts.
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Affiliation(s)
- Maria N Barrachina
- Vascular Biology Program, Boston Children’s Hospital, Boston, MA, 02115 USA
- Harvard Medical School, Department of Surgery, Boston Children’s Hospital, Boston, MA, 02115 USA
| | - Gerard Pernes
- Haematopoiesis and Leukocyte Biology, Baker Heart and Diabetes Institute, Melbourne, VIC, Australia
| | - Isabelle C Becker
- Vascular Biology Program, Boston Children’s Hospital, Boston, MA, 02115 USA
- Harvard Medical School, Department of Surgery, Boston Children’s Hospital, Boston, MA, 02115 USA
| | - Isabelle Allaeys
- Centre de Recherche du CHU de Québec-Université Laval and Centre de Recherche ARThrite, Québec, QC, G1V4G2 Canada
| | - Thomas I. Hirsch
- Vascular Biology Program, Boston Children’s Hospital, Boston, MA, 02115 USA
- Harvard Medical School, Department of Surgery, Boston Children’s Hospital, Boston, MA, 02115 USA
| | - Dafna J Groeneveld
- Department of Pathobiology and Diagnostic Investigation, Michigan State University, East Lansing, MI, USA
| | - Abdullah O. Khan
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Vincent Drive, Birmingham, U.K, B15 2TT
- MRC Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine and National Institute of Health Research (NIHR) Oxford Biomedical Research Centre, University of Oxford, Oxford, U.K. OX3 9DS
| | - Daniela Freire
- Vascular Biology Program, Boston Children’s Hospital, Boston, MA, 02115 USA
| | - Karen Guo
- Vascular Biology Program, Boston Children’s Hospital, Boston, MA, 02115 USA
| | - Estelle Carminita
- Vascular Biology Program, Boston Children’s Hospital, Boston, MA, 02115 USA
- Harvard Medical School, Department of Surgery, Boston Children’s Hospital, Boston, MA, 02115 USA
| | - Pooranee K Morgan
- Haematopoiesis and Leukocyte Biology, Baker Heart and Diabetes Institute, Melbourne, VIC, Australia
| | - Thomas J Collins
- Haematopoiesis and Leukocyte Biology, Baker Heart and Diabetes Institute, Melbourne, VIC, Australia
| | - Natalie A Mellett
- Metabolomics, Baker Heart and Diabetes Institute, Melbourne, VIC, Australia
| | - Zimu Wei
- Department of Pathobiology and Diagnostic Investigation, Michigan State University, East Lansing, MI, USA
| | - Ibrahim Almazni
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Vincent Drive, Birmingham, U.K, B15 2TT
| | - Joseph E. Italiano
- Vascular Biology Program, Boston Children’s Hospital, Boston, MA, 02115 USA
- Harvard Medical School, Department of Surgery, Boston Children’s Hospital, Boston, MA, 02115 USA
| | - James Luyendyk
- Department of Pathobiology and Diagnostic Investigation, Michigan State University, East Lansing, MI, USA
| | - Peter J Meikle
- Metabolomics, Baker Heart and Diabetes Institute, Melbourne, VIC, Australia
| | - Mark Puder
- Vascular Biology Program, Boston Children’s Hospital, Boston, MA, 02115 USA
- Harvard Medical School, Department of Surgery, Boston Children’s Hospital, Boston, MA, 02115 USA
| | - Neil V. Morgan
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Vincent Drive, Birmingham, U.K, B15 2TT
| | - Eric Boilard
- Centre de Recherche du CHU de Québec-Université Laval and Centre de Recherche ARThrite, Québec, QC, G1V4G2 Canada
| | - Andrew J Murphy
- Haematopoiesis and Leukocyte Biology, Baker Heart and Diabetes Institute, Melbourne, VIC, Australia
| | - Kellie R Machlus
- Vascular Biology Program, Boston Children’s Hospital, Boston, MA, 02115 USA
- Harvard Medical School, Department of Surgery, Boston Children’s Hospital, Boston, MA, 02115 USA
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6
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Mezzano D, Harrison P, Frelinger AL, Mumford AD, Noris P, Lordkipanidzé M, Gresele P. Expert opinion on the use of platelet secretion assay for the diagnosis of inherited platelet function disorders: Communication from the ISTH SSC Subcommittee on Platelet Physiology. J Thromb Haemost 2022; 20:2127-2135. [PMID: 35770723 DOI: 10.1111/jth.15781] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Revised: 06/06/2022] [Accepted: 06/07/2022] [Indexed: 11/29/2022]
Abstract
Assessment of platelet secretion is crucial for diagnosing suspected inherited platelet function disorders (IPFD). A previous survey of the SSC on Platelet Physiology of the ISTH and a comprehensive review highlighted that most of the platelet secretion assays (PSAs) lack standardization and validation. The aim of this study was to provide expert consensus guidance on the use of PSAs for IPFD diagnosis. We surveyed 26 experts from 10 different countries using the RAND/UCLA methodology, to attain a consensus on sensitivity, specificity, feasibility, time to readout, and cost of most PSAs. Answers were then graded in three categories: appropriate, uncertain, and inappropriate. Equivocal or misinterpretable statements required a second and third round survey involving 14 of the original 26 experts. We report here the consolidated results of the entire procedure. There was uniform agreement on several general statements, including that PSAs should be performed in hemostasis laboratories as first line diagnostic tests even in patients with normal platelet aggregation, and should include a δ-granule secretion marker. Among the specific assays examined, lumiaggregometry, other luciferin/luciferase-based assays, high-performance liquid chromatography methods, radiolabeled-serotonin based assays, and whole-mount transmission electron microscopy were rated as appropriate for the measurement of δ-granule release, and platelet P-selectin expression by flow cytometry and released proteins by ELISA for α-granule release. For most of the other PSAs, the expert opinions were widely dispersed. Lack of expert consensus on many PSAs clearly indicates an unmet need for rigorous standardization, multicenter comparison of results, and validation of PSAs for clinical laboratory practice.
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Affiliation(s)
- Diego Mezzano
- Department of Hematology-Oncology, School of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Paul Harrison
- Institute of Inflammation and Ageing, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
| | - Andrew L Frelinger
- Division of Hematology/Oncology, Center for Platelet Research Studies, Boston Children's Hospital, Dana-Farber/Boston Children's Cancer and Blood Disorders Center, Boston, Massachusetts, USA
- Harvard Medical School, Boston, Massachusetts, USA
| | - Andrew D Mumford
- School of Cellular and Molecular Medicine, University of Bristol, Bristol, UK
| | - Patrizia Noris
- Department of Internal Medicine, IRCCS Policlinico San Matteo Foundation and University of Pavia, Pavia, Italy
| | - Marie Lordkipanidzé
- Faculté de Pharmacie, Université de Montréal, Montréal, Quebec, Canada
- Research Center, Montreal Heart Institute, Montréal, Quebec, Canada
| | - Paolo Gresele
- Department of Medicine and Surgery, University of Perugia, Perugia, Italy
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7
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Stapley RJ, Poulter NS, Khan AO, Smith CW, Bignell P, Fratter C, Lester W, Lowe G, Morgan NV. Rare missense variants in Tropomyosin-4 (TPM4) are associated with platelet dysfunction, cytoskeletal defects, and excessive bleeding. J Thromb Haemost 2022; 20:478-485. [PMID: 34758189 DOI: 10.1111/jth.15584] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Revised: 11/01/2021] [Accepted: 11/05/2021] [Indexed: 01/03/2023]
Abstract
BACKGROUND A significant challenge is faced for the genetic diagnosis of inherited platelet disorders in which candidate genetic variants can be found in more than 100 bleeding, thrombotic, and platelet disorder genes, especially within families in which there are both normal and low platelet counts. Genetic variants of unknown clinical significance (VUS) are found in a significant proportion of such patients in which functional studies are required to prove pathogenicity. OBJECTIVE To identify the genetic cause in patients with a suspected platelet disorder and subsequently perform a detailed functional analysis of the candidate genetic variants found. METHODS Genetic and functional studies were undertaken in three patients in two unrelated families with a suspected platelet disorder and excessive bleeding. A targeted gene panel of previously known bleeding and platelet genes was used to identify plausible genetic variants. Deep platelet phenotyping was performed using platelet spreading analysis, transmission electron microscopy, immunofluorescence, and platelet function testing using lumiaggregometry and flow cytometry. RESULTS We report rare conserved missense variants (p.R182C and p.A183V) in TPM4 encoding tromomyosin-4 in 3 patients. Deep platelet phenotyping studies revealed similar platelet function defects across the 3 patients including reduced platelet secretion, and aggregation and spreading defects suggesting that TPM4 missense variants impact platelet function and show a disordered pattern of tropomyosin staining. CONCLUSIONS Genetic and functional TPM4 defects are reported making TPM4 a diagnostic grade tier 1 gene and highlights the importance of including TPM4 in diagnostic genetic screening for patients with significant bleeding and undiagnosed platelet disorders, particularly for those with a normal platelet count.
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Affiliation(s)
- Rachel J Stapley
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
| | - Natalie S Poulter
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
- Centre of Membrane Proteins and Receptors (COMPARE), Universities of Birmingham and Nottingham, Midlands, UK
| | - Abdullah O Khan
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
| | - Christopher W Smith
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
| | - Patricia Bignell
- Oxford Genetics Laboratories, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Carl Fratter
- Oxford Genetics Laboratories, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Will Lester
- Comprehensive Care Haemophilia Centre, University Hospital Birmingham NHS Foundation Trust, Birmingham, UK
| | - Gillian Lowe
- Comprehensive Care Haemophilia Centre, University Hospital Birmingham NHS Foundation Trust, Birmingham, UK
| | - Neil V Morgan
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
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8
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Rosenberg N, Dardik R, Hauschner H, Nakav S, Barel O, Luboshitz J, Yacobovich J, Tamary H, Kenet G. Mutations in RASGRP2 gene identified in patients misdiagnosed as Glanzmann thrombasthenia patients. Blood Cells Mol Dis 2021; 89:102560. [PMID: 33711653 DOI: 10.1016/j.bcmd.2021.102560] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 02/24/2021] [Accepted: 03/01/2021] [Indexed: 11/30/2022]
Abstract
INTRODUCTION Glanzmann thrombasthenia (GT) is a severe inherited platelet function disorder (IPFD), presenting with bleeding diathesis and impaired platelet aggregation, is caused by mutations in the genes ITGA2B or ITGB3. AIM We aimed to study the genetic cause of IPFD mimicking GT. METHODS During 2017-2019, 16 patients were referred to our tertiary center with bleeding symptoms, impaired platelet aggregation and normal platelet count and size. RESULTS Using flow cytometry, 13/16 patients were diagnosed with GT, yet three patients displayed normal surface expression of the integrins αIIbβ3 and αvβ3, as well as normal integrin αIIbβ3 activation following incubation with the activating monoclonal antibody anti-LIBS6, while platelet activation following ADP or epinephrine was impaired. Whole exome sequencing detected 2 variants in RASGRP2 gene in all 3 patients. DISCUSSION Both RASGRP2 mutations predicted frameshift, premature stop codon (p. I427Mfs*92 and p. R494Afs*54, respectively) and truncated calcium-sensing guanine nucleotide exchange factor [CalDAG-GEFI]- the major signaling molecule that regulates integrin-mediated aggregation and granule secretion, causing IPFD-18. CONCLUSION Patients who suffer from bleeding diathesis without immune dysregulation, may be mistakenly diagnosed as GT. Further studies are required to confirm the diagnosis of specific IPFD.
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Affiliation(s)
- Nurit Rosenberg
- The Israeli National Hemophilia Center and Thrombosis Institute, Sheba Medical Center, Tel Hashomer, Israel; Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel; Amalia Biron Research Institute of Thrombosis and Hemostasis, Sheba Medical Center, Tel Hashomer, and Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Rima Dardik
- The Israeli National Hemophilia Center and Thrombosis Institute, Sheba Medical Center, Tel Hashomer, Israel
| | - Hagit Hauschner
- The Israeli National Hemophilia Center and Thrombosis Institute, Sheba Medical Center, Tel Hashomer, Israel; Amalia Biron Research Institute of Thrombosis and Hemostasis, Sheba Medical Center, Tel Hashomer, and Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Sigal Nakav
- Coagulation and Hemostasis Laboratory, Hematology Laboratories, Rabin Medical Center, Beilinson Hospital, Petah Tikva, Israel
| | - Ortal Barel
- Bioinformatic Unit, Sheba Cancer Research Center, Tel-Hashomer, Israel
| | - Jacob Luboshitz
- The Israeli National Hemophilia Center and Thrombosis Institute, Sheba Medical Center, Tel Hashomer, Israel; Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Joanne Yacobovich
- Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel; Pediatric Hematology, Schneider Children's Medical Center, Petach-Tikva; Israel
| | - Hannah Tamary
- Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel; Pediatric Hematology, Schneider Children's Medical Center, Petach-Tikva; Israel
| | - Gili Kenet
- The Israeli National Hemophilia Center and Thrombosis Institute, Sheba Medical Center, Tel Hashomer, Israel; Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel; Amalia Biron Research Institute of Thrombosis and Hemostasis, Sheba Medical Center, Tel Hashomer, and Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel.
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9
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Almazni I, Chudakou P, Dawson-Meadows A, Downes K, Freson K, Mason J, Page P, Reay K, Myers B, Morgan NV. A novel RUNX1 exon 3 - 7 deletion causing a familial platelet disorder. Platelets 2021; 33:320-323. [PMID: 33616470 DOI: 10.1080/09537104.2021.1887470] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Familial Platelet Disorder with associated Myeloid Malignancy (FPDMM) is a rare inherited disorder confirmed with the presence of a pathogenic germline RUNX1 variant and is thought to be heavily underdiagnosed. RUNX1 has also been found to be mutated in up to 10% of adult AML cases and other cell malignancies. We performed targeted next-generation sequencing and subsequent MLPA analysis in a kindred with multiple affected individuals with low platelet counts and a bleeding history. We detected a novel heterozygous exon 3-7 large deletion in the RUNX1 gene in all affected family members which is predicted to remove all of the Runt-homology DNA-binding domain and a portion of the Activation domain. Our results show that the combination of targeted NGS and MLPA analysis is an effective way to detect copy number variants (CNVs) which would be missed by conventional sequencing methods. This precise diagnosis offers the possibility of accurate counseling and clinical management in such patients who could go onto develop other cell malignancies.
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Affiliation(s)
- Ibrahim Almazni
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
| | - Pavel Chudakou
- Department of Haematology, Lincoln County Hospital, Lincoln, UK
| | | | - Kate Downes
- East Genomic Laboratory Hub, Cambridge University Hospitals, Cambridge, UK
| | - Kathleen Freson
- Center for Molecular and Vascular Biology, Department of Cardiovascular Sciences, University of Leuven, Leuven, Belgium
| | - Joanne Mason
- West Midlands Regional Genetics Laboratory, Birmingham Women's Hospital, Birmingham, UK
| | - Paula Page
- West Midlands Regional Genetics Laboratory, Birmingham Women's Hospital, Birmingham, UK
| | - Kim Reay
- West Midlands Regional Genetics Laboratory, Birmingham Women's Hospital, Birmingham, UK
| | - Bethan Myers
- Department of Haematology, Lincoln County Hospital, Lincoln, UK.,Department of Haematology, University Hospitals of Leicester, Leicester, UK
| | - Neil V Morgan
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
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10
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Khan AO, Stapley RJ, Pike JA, Wijesinghe SN, Reyat JS, Almazni I, Machlus KR, Morgan NV. Novel gene variants in patients with platelet-based bleeding using combined exome sequencing and RNAseq murine expression data. J Thromb Haemost 2021; 19:262-268. [PMID: 33021027 DOI: 10.1111/jth.15119] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 09/23/2020] [Accepted: 09/28/2020] [Indexed: 01/12/2023]
Abstract
Essentials Identifying genetic variants in platelet disorders is challenging due to its heterogenous nature. We combine WES, RNAseq, and python-based bioinformatics to identify novel gene variants. We find novel candidates in patient data by cross-referencing against a murine RNAseq model of thrombopoiesis. This innovative combined bioinformatic approach provides novel data for future research in the field. ABSTRACT: Background The UK Genotyping and Phenotyping of Platelets study has recruited and analyzed 129 patients with suspected heritable bleeding. Previously, 55 individuals had a definitive genetic diagnosis based on whole exome sequencing (WES) and platelet morphological and functional testing. A significant challenge in this field is defining filtering criteria to identify the most likely candidate mutations for diagnosis and further study. Objective Identify candidate gene mutations for the remaining 74 patients with platelet-based bleeding with unknown genetic cause, forming the basis of future re-recruitment and further functional testing and assessment. Methods Using python-based data frame indexing, we first identify and filter all novel and rare variants using a panel of 116 genes known to cause bleeding across the full cohort of WES data. This identified new variants not previously reported in this cohort. We then index the remaining patients, with rare or novel variants in known bleeding genes against a murine RNA sequencing dataset that models proplatelet-forming megakaryocytes. Results Filtering against known genes identified candidate variants in 59 individuals, including novel variants in several known genes. In the remaining cohort of "unknown" patients, indexing against differentially expressed genes revealed candidate gene variants in several novel unreported genes, focusing on 14 patients with a severe clinical presentation. Conclusions We identified candidate mutations in a cohort of patients with no previous genetic diagnosis. This work involves innovative coupling of RNA sequencing and WES to identify candidate variants forming the basis of future study in a significant number of undiagnosed patients.
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Affiliation(s)
- Abdullah O Khan
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
| | - Rachel J Stapley
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
| | - Jeremy A Pike
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
| | - Susanne N Wijesinghe
- Institute of Inflammation and Ageing, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
| | - Jasmeet S Reyat
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
| | - Ibrahim Almazni
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
| | - Kellie R Machlus
- Hematology Division, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
| | - Neil V Morgan
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
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11
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Almazni I, Stapley RJ, Khan AO, Morgan NV. A comprehensive bioinformatic analysis of 126 patients with an inherited platelet disorder to identify both sequence and copy number genetic variants. Hum Mutat 2020; 41:1848-1865. [PMID: 32935436 DOI: 10.1002/humu.24114] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 07/28/2020] [Accepted: 09/04/2020] [Indexed: 12/25/2022]
Abstract
Inherited bleeding disorders (IBDs) comprise an extremely heterogeneous group of diseases that reflect abnormalities of blood vessels, coagulation proteins, and platelets. Previously the UK-GAPP study has used whole-exome sequencing in combination with deep platelet phenotyping to identify pathogenic genetic variants in both known and novel genes in approximately 40% of the patients. To interrogate the remaining "unknown" cohort and improve this detection rate, we employed an IBD-specific gene panel of 119 genes using the Congenica Clinical Interpretation Platform to detect both single-nucleotide variants and copy number variants in 126 patients. In total, 135 different heterozygous variants in genes implicated in bleeding disorders were identified. Of which, 22 were classified pathogenic, 26 likely pathogenic, and the remaining were of uncertain significance. There were marked differences in the number of reported variants in individuals between the four patient groups: platelet count (35), platelet function (43), combined platelet count and function (59), and normal count (17). Additionally, we report three novel copy number variations (CNVs) not previously detected. We show that a combined single-nucleotide variation (SNV)/CNV analysis using the Congenica platform not only improves detection rates for IBDs, suggesting that such an approach can be applied to other genetic disorders where there is a high degree of heterogeneity.
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Affiliation(s)
- Ibrahim Almazni
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
| | - Rachel J Stapley
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
| | - Abdullah O Khan
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
| | - Neil V Morgan
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
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12
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Munnix ICA, Van Oerle R, Verhezen P, Kuijper P, Hackeng CM, Hopman-Kerkhoff HIJ, Hudig F, Van De Kerkhof D, Leyte A, De Maat MPM, Oude Elferink RFM, Ruinemans-Koerts J, Schoorl M, Slomp J, Soons H, Stroobants A, Van Wijk E, Henskens YMC. Harmonizing light transmission aggregometry in the Netherlands by implementation of the SSC-ISTH guideline. Platelets 2020; 32:516-523. [PMID: 32522065 DOI: 10.1080/09537104.2020.1771549] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Light transmission aggregometry (LTA) is considered the gold standard method for evaluation of platelet function. However, there are a lot of variation in protocols (pre-analytical procedures and agonist concentrations) and results. The aim of our study was to establish a national LTA protocol, to investigate the effect of standardization and to define national reference values for LTA. The SSC guideline was used as base for a national procedure. Almost all recommendations of the SSC were followed e.g. no adjustment of PRP, citrate concentration of 109 mM, 21 needle gauge, fasting, resting time for whole blood and PRP, centrifugation time, speed and agonists concentrations. LTA of healthy volunteers was measured in a total of 16 hospitals with 5 hospitals before and after standardization. Results of more than 120 healthy volunteers (maximum aggregation %) were collected, with participating laboratories using 4 different analyzers with different reagents. Use of low agonist concentrations showed high variation before and after standardization, with the exception of collagen. For most high agonist concentrations (ADP, collagen, ristocetin, epinephrine and arachidonic acid) variability in healthy subjects decreased after standardization. We can conclude that a standardized Dutch protocol for LTA, based on the SSC guideline, does not result in smaller variability in healthy volunteers for all agonist concentrations.
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Affiliation(s)
- I C A Munnix
- Department of Clinical Chemistry, Canisius-Wilhelmina Hospital, Nijmegen, The Netherlands
| | - R Van Oerle
- Central Diagnostic Laboratory, Maastricht University Medical Centre +, Maastricht, The Netherlands
| | - P Verhezen
- Central Diagnostic Laboratory, Maastricht University Medical Centre +, Maastricht, The Netherlands
| | - P Kuijper
- Clinical Laboratory, Maxima Medical Centre, Veldhoven, The Netherlands
| | - C M Hackeng
- Department of Clinical Chemistry, St. Antonius Hospital, Nieuwegein, The Netherlands
| | | | - F Hudig
- LabWest, Haga Teaching Hospital, The Hague, The Netherlands
| | - D Van De Kerkhof
- Clinical Laboratory, Catharina Hospital, Eindhoven, The Netherlands
| | - A Leyte
- Department of Clinical Chemistry, OLVG Laboratoria BV, Amsterdam, The Netherlands
| | - M P M De Maat
- Department of Hematology, Erasmus University Medical Centre Rotterdam, Rotterdam, The Netherlands
| | | | - J Ruinemans-Koerts
- Department of Clinical Chemistry and Haematology, Rijnstate Hospital, Arnhem, The Netherlands
| | - M Schoorl
- Department of Clinical Chemistry, Haematology & Immunology,Northwest Clinics, Alkmaar, The Netherlands
| | - J Slomp
- Department of Clinical Chemistry, Medlon, Location Medisch Spectrum Twente, Enschede, The Netherlands
| | - H Soons
- Department of Clinical Chemistry, St. Anna Hospital, Geldrop, The Netherlands
| | - A Stroobants
- Department of Clinical Chemistry, AmsterdamUMC Location AMC, Amsterdam, The Netherlands
| | - E Van Wijk
- Department of Clinical Chemistry, St. Elisabeth Hospital, Tilburg, The Netherlands
| | - Y M C Henskens
- Central Diagnostic Laboratory, Maastricht University Medical Centre +, Maastricht, The Netherlands
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13
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Zaninetti C, Greinacher A. Diagnosis of Inherited Platelet Disorders on a Blood Smear. J Clin Med 2020; 9:jcm9020539. [PMID: 32079152 PMCID: PMC7074415 DOI: 10.3390/jcm9020539] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2020] [Revised: 02/08/2020] [Accepted: 02/12/2020] [Indexed: 12/12/2022] Open
Abstract
Inherited platelet disorders (IPDs) are rare diseases featured by low platelet count and defective platelet function. Patients have variable bleeding diathesis and sometimes additional features that can be congenital or acquired. Identification of an IPD is desirable to avoid misdiagnosis of immune thrombocytopenia and the use of improper treatments. Diagnostic tools include platelet function studies and genetic testing. The latter can be challenging as the correlation of its outcomes with phenotype is not easy. The immune-morphological evaluation of blood smears (by light- and immunofluorescence microscopy) represents a reliable method to phenotype subjects with suspected IPD. It is relatively cheap, not excessively time-consuming and applicable to shipped samples. In some forms, it can provide a diagnosis by itself, as for MYH9-RD, or in addition to other first-line tests as aggregometry or flow cytometry. In regard to genetic testing, it can guide specific sequencing. Since only minimal amounts of blood are needed for the preparation of blood smears, it can be used to characterize thrombocytopenia in pediatric patients and even newborns further. In principle, it is based on visualizing alterations in the distribution of proteins, which result from specific genetic mutations by using monoclonal antibodies. It can be applied to identify deficiencies in membrane proteins, disturbed distribution of cytoskeletal proteins, and alpha as well as delta granules. On the other hand, mutations associated with impaired signal transduction are difficult to identify by immunofluorescence of blood smears. This review summarizes technical aspects and the main diagnostic patterns achievable by this method.
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Affiliation(s)
- Carlo Zaninetti
- Institut für Immunologie und Transfusionsmedizin, Universitätsmedizin Greifswald, 17489 Greifswald, Germany;
- University of Pavia, and IRCCS Policlinico San Matteo Foundation, 27100 Pavia, Italy
- PhD Program of Experimental Medicine, University of Pavia, 27100 Pavia, Italy
| | - Andreas Greinacher
- Institut für Immunologie und Transfusionsmedizin, Universitätsmedizin Greifswald, 17489 Greifswald, Germany;
- Correspondence: ; Tel.: +49-3834-865482; Fax: +49-3834-865489
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14
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Montague SJ, Lim YJ, Lee WM, Gardiner EE. Imaging Platelet Processes and Function-Current and Emerging Approaches for Imaging in vitro and in vivo. Front Immunol 2020; 11:78. [PMID: 32082328 PMCID: PMC7005007 DOI: 10.3389/fimmu.2020.00078] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2019] [Accepted: 01/13/2020] [Indexed: 12/22/2022] Open
Abstract
Platelets are small anucleate cells that are essential for many biological processes including hemostasis, thrombosis, inflammation, innate immunity, tumor metastasis, and wound healing. Platelets circulate in the blood and in order to perform all of their biological roles, platelets must be able to arrest their movement at an appropriate site and time. Our knowledge of how platelets achieve this has expanded as our ability to visualize and quantify discreet platelet events has improved. Platelets are exquisitely sensitive to changes in blood flow parameters and so the visualization of rapid intricate platelet processes under conditions found in flowing blood provides a substantial challenge to the platelet imaging field. The platelet's size (~2 μm), rapid activation (milliseconds), and unsuitability for genetic manipulation, means that appropriate imaging tools are limited. However, with the application of modern imaging systems to study platelet function, our understanding of molecular events mediating platelet adhesion from a single-cell perspective, to platelet recruitment and activation, leading to thrombus (clot) formation has expanded dramatically. This review will discuss current platelet imaging techniques in vitro and in vivo, describing how the advancements in imaging have helped answer/expand on platelet biology with a particular focus on hemostasis. We will focus on platelet aggregation and thrombus formation, and how platelet imaging has enhanced our understanding of key events, highlighting the knowledge gained through the application of imaging modalities to experimental models in vitro and in vivo. Furthermore, we will review the limitations of current imaging techniques, and questions in thrombosis research that remain to be addressed. Finally, we will speculate how the same imaging advancements might be applied to the imaging of other vascular cell biological functions and visualization of dynamic cell-cell interactions.
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Affiliation(s)
- Samantha J. Montague
- ACRF Department of Cancer Biology and Therapeutics, The John Curtin School of Medical Research, The Australian National University, Canberra, ACT, Australia
| | - Yean J. Lim
- ACRF Department of Cancer Biology and Therapeutics, The John Curtin School of Medical Research, The Australian National University, Canberra, ACT, Australia
- Research School of Electrical, Energy and Materials Engineering, The Australian National University, Canberra, ACT, Australia
| | - Woei M. Lee
- ACRF Department of Cancer Biology and Therapeutics, The John Curtin School of Medical Research, The Australian National University, Canberra, ACT, Australia
- Research School of Electrical, Energy and Materials Engineering, The Australian National University, Canberra, ACT, Australia
| | - Elizabeth E. Gardiner
- ACRF Department of Cancer Biology and Therapeutics, The John Curtin School of Medical Research, The Australian National University, Canberra, ACT, Australia
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15
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Khan AO, Maclachlan A, Lowe GC, Nicolson PLR, Ghaithi RA, Thomas SG, Watson SP, Pike JA, Morgan NV. High-throughput platelet spreading analysis: a tool for the diagnosis of platelet-based bleeding disorders. Haematologica 2019; 105:e124-e128. [PMID: 31221775 DOI: 10.3324/haematol.2019.225912] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Affiliation(s)
- Abdullah O Khan
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham
| | - Annabel Maclachlan
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham
| | - Gillian C Lowe
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham
| | - Phillip L R Nicolson
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham
| | - Rashid Al Ghaithi
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham
| | - Steven G Thomas
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham.,Centre of Membrane and Protein and Receptors (COMPARE), University of Birmingham and University of Nottingham, Midlands, UK
| | - Steve P Watson
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham.,Centre of Membrane and Protein and Receptors (COMPARE), University of Birmingham and University of Nottingham, Midlands, UK
| | - Jeremy A Pike
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham.,Centre of Membrane and Protein and Receptors (COMPARE), University of Birmingham and University of Nottingham, Midlands, UK
| | - Neil V Morgan
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham
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16
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Simplifying the diagnosis of inherited platelet disorders? The new tools do not make it any easier. Blood 2019; 133:2478-2483. [PMID: 30858232 DOI: 10.1182/blood-2019-01-852350] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Accepted: 02/28/2019] [Indexed: 12/25/2022] Open
Abstract
The molecular causes of many inherited platelet disorders are being unraveled. Next-generation sequencing facilitates diagnosis in 30% to 50% of patients. However, interpretation of genetic variants is challenging and requires careful evaluation in the context of a patient's phenotype. Before detailed testing is initiated, the treating physician and patient should establish an understanding of why testing is being performed and discuss potential consequences, especially before testing for variants in genes associated with an increased risk for hematologic malignancies.
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17
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Gresele P, Bury L, Mezzasoma AM, Falcinelli E. Platelet function assays in diagnosis: an update. Expert Rev Hematol 2019; 12:29-46. [DOI: 10.1080/17474086.2019.1562333] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Paolo Gresele
- Department of Medicine, Section of Internal and Cardiovascular Medicine, University of Perugia, Perugia, Italy
| | - Loredana Bury
- Department of Medicine, Section of Internal and Cardiovascular Medicine, University of Perugia, Perugia, Italy
| | - Anna Maria Mezzasoma
- Department of Medicine, Section of Internal and Cardiovascular Medicine, University of Perugia, Perugia, Italy
| | - Emanuela Falcinelli
- Department of Medicine, Section of Internal and Cardiovascular Medicine, University of Perugia, Perugia, Italy
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18
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Lowe GC, Fickowska R, Al Ghaithi R, Maclachlan A, Harrison P, Lester W, Watson SP, Myers B, Clark J, Morgan NV. Investigation of the contribution of an underlying platelet defect in women with unexplained heavy menstrual bleeding. Platelets 2018; 30:56-65. [PMID: 30520671 PMCID: PMC6406209 DOI: 10.1080/09537104.2018.1543865] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Heavy menstrual bleeding (HMB) is often undiagnosed in women and can cause discomfort and distress. A haemostatic cause for excessive bleeding is often not routinely investigated and can lead to hysterectomy at an early age. A prospective cohort study was carried out to determine whether certain patients with unexplained HMB have an underlying platelet function defect (PFD). The Genotyping and Phenotyping of Platelets (GAPP) study recruited 175 women with HMB and 44 unrelated volunteers from 25 Haemophilia Centres across the UK, and a tertiary gynaecology service. Bleeding history was assessed using the International Society on Thrombosis and Haemostasis Bleeding Assessment Tool (ISTH-BAT). Platelet count, platelet size, haemoglobin and mean corpuscular volume were measured in whole blood using the Sysmex XN-1000 Haematology Analyzer. Platelet function testing using lumiaggregometry and flow cytometry was performed in patients included in this study. A PFD was identified in 47% (82/175) of patients with HMB. Cutaneous bleeding was the most frequent additional bleeding symptom (89% in PFD and 83% with no PFD). Whole blood platelet count was significantly lower (P < 0.0001) between the PFD group and no PFD group. The prevalence of anaemia did not differ between patients and healthy volunteers. Clinical evaluation alone is insufficient to determine presence of an underlying PFD in patients with HMB. Platelet function tests may be considered and clinical guidelines may include them in their algorithms. An appropriate diagnosis and subsequent tailored management of HMB may prevent unnecessary surgery and help manage future haemostatic challenges.
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Affiliation(s)
- Gillian C Lowe
- a Comprehensive Care Haemophilia Centre , University Hospital Birmingham NHS Foundation Trust , Birmingham , UK
| | - Roksana Fickowska
- b Institute of Cardiovascular Sciences, College of Medical and Dental Sciences , University of Birmingham , Birmingham , UK
| | - Rashid Al Ghaithi
- c Institute of Inflammation and Ageing, College of Medical and Dental Sciences , University of Birmingham , Birmingham , UK
| | - Annabel Maclachlan
- b Institute of Cardiovascular Sciences, College of Medical and Dental Sciences , University of Birmingham , Birmingham , UK
| | - Paul Harrison
- c Institute of Inflammation and Ageing, College of Medical and Dental Sciences , University of Birmingham , Birmingham , UK
| | - Will Lester
- a Comprehensive Care Haemophilia Centre , University Hospital Birmingham NHS Foundation Trust , Birmingham , UK
| | - Steve P Watson
- b Institute of Cardiovascular Sciences, College of Medical and Dental Sciences , University of Birmingham , Birmingham , UK
| | - Bethan Myers
- d Department of Haematology , Lincoln County Hospital , Lincoln , UK.,e Haemostasis & Thrombosis Unit, Leicester Royal Infirmary , University Hospitals Of Leicester NHS Trust , Leicester , UK
| | - Justin Clark
- f Department of Gynaecology , Birmingham Women's and Children's NHS Foundation Trust , Birmingham , UK
| | - Neil V Morgan
- b Institute of Cardiovascular Sciences, College of Medical and Dental Sciences , University of Birmingham , Birmingham , UK
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19
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Romasko EJ, Devkota B, Biswas S, Jayaraman V, Rajagopalan R, Dulik MC, Thom CS, Choi J, Jairam S, Scarano MI, Krantz ID, Spinner NB, Conlin LK, Lambert MP. Utility and limitations of exome sequencing in the molecular diagnosis of pediatric inherited platelet disorders. Am J Hematol 2018; 93:8-16. [PMID: 28960434 DOI: 10.1002/ajh.24917] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Revised: 09/21/2017] [Accepted: 09/23/2017] [Indexed: 12/21/2022]
Abstract
Inherited platelet disorders (IPD) are a heterogeneous group of rare disorders that affect platelet number and function and often predispose to other significant medical complications. In spite of the identification of over 50 IPD disease-associated genes, a molecular diagnosis is only identified in a minority (10%) of affected patients without a clinically suspected etiology. We studied a cohort of 21 pediatric patients with suspected IPDs by exome sequencing (ES) to: (1) examine the performance of the exome test for IPD genes, (2) determine if this exome-wide diagnostic test provided a higher diagnostic yield than has been previously reported, (3) to evaluate the frequency of variants of uncertain significance identified, and (4) to identify candidate variants for functional evaluation in patients with an uncertain or negative diagnosis. We established a high priority gene list of 53 genes, evaluated exome capture kit performance, and determined the coverage for these genes and disease-related variants. We identified likely disease causing variants in 5 of the 21 probands (23.8%) and variants of uncertain significance in 52% of patients studied. In conclusion, ES has the potential to molecularly diagnose causes of IPD, and to identify candidate genes for functional evaluation. Robust exome sequencing also requires that coverage of genes known to be associated with clinical findings of interest need to be carefully examined and supplemented if necessary. Clinicians who undertake ES should understand the limitations of the test and the full significance of results that may be returned.
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Affiliation(s)
- Edward J. Romasko
- Division of Human Genetics; Children's Hospital of Philadelphia; Philadelphia Pennsylvania
| | - Batsal Devkota
- Department of Biomedical and Health Informatics; Children's Hospital of Philadelphia; Philadelphia Pennsylvania
| | - Sawona Biswas
- Division of Human Genetics; Children's Hospital of Philadelphia; Philadelphia Pennsylvania
| | - Vijayakumar Jayaraman
- Division of Human Genetics; Children's Hospital of Philadelphia; Philadelphia Pennsylvania
| | - Ramakrishnan Rajagopalan
- Department of Biomedical and Health Informatics; Children's Hospital of Philadelphia; Philadelphia Pennsylvania
| | - Matthew C. Dulik
- Division of Genomic Diagnostics; Children's Hospital of Philadelphia; Philadelphia Pennsylvania
| | - Christopher S. Thom
- Department of Pediatrics; University of Pennsylvania School of Medicine, Philadelphia; Philadelphia Pennsylvania
| | - Jiwon Choi
- Division of Human Genetics; Children's Hospital of Philadelphia; Philadelphia Pennsylvania
| | - Sowmya Jairam
- Department of Pathology; Memorial Sloan Kettering Cancer Center; New York New York
| | | | - Ian D. Krantz
- Division of Human Genetics; Children's Hospital of Philadelphia; Philadelphia Pennsylvania
- Department of Pediatrics; University of Pennsylvania School of Medicine, Philadelphia; Philadelphia Pennsylvania
| | - Nancy B. Spinner
- Division of Genomic Diagnostics; Children's Hospital of Philadelphia; Philadelphia Pennsylvania
- Department of Pathology and Laboratory Medicine; University of Pennsylvania School of Medicine; Philadelphia Pennsylvania
| | - Laura K. Conlin
- Division of Genomic Diagnostics; Children's Hospital of Philadelphia; Philadelphia Pennsylvania
- Department of Pathology and Laboratory Medicine; University of Pennsylvania School of Medicine; Philadelphia Pennsylvania
| | - Michele P. Lambert
- Department of Pediatrics; University of Pennsylvania School of Medicine, Philadelphia; Philadelphia Pennsylvania
- Division of Hematology; Children's Hospital of Philadelphia; Philadelphia Pennsylvania
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20
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Nisar SP, Lordkipanidzé M, Jones ML, Dawood BB, Murden S, Cunningham MR, Mumford AD, Wilde JT, Watson SP, Lowe GC, Mundell SJ. A novel thromboxane A2 receptor N42S variant results in reduced surface expression and platelet dysfunction. Thromb Haemost 2017; 111:923-32. [DOI: 10.1160/th13-08-0672] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2013] [Accepted: 12/19/2013] [Indexed: 11/05/2022]
Abstract
SummaryA small number of thromboxane receptor variants have been described in patients with a bleeding history that result in platelet dysfunction. We have identified a patient with a history of significant bleeding, who expresses a novel heterozygous thromboxane receptor variant that predicts an asparagine to serine substitution (N42S). This asparagine is conserved across all class A GPCRs, suggesting a vital role for receptor structure and function. We investigated the functional consequences of the TP receptor heterozygous N42S substitution by performing platelet function studies on platelet-rich plasma taken from the patient and healthy controls. We investigated the N42S mutation by expressing the wild-type (WT) and mutant receptor in human embryonic kidney (HEK) cells. Aggregation studies showed an ablation of arachidonic acid responses in the patient, whilst there was right-ward shift of the U46619 concentration response curve (CRC). Thromboxane generation was unaffected. Calcium mobilisation studies in cells lines showed a rightward shift of the U46619 CRC in N42S–expressing cells compared to WT. Radioligand binding studies revealed a reduction in BMax in platelets taken from the patient and in N42S–expressing cells, whilst cell studies confirmed poor surface expression. We have identified a novel thromboxane receptor variant, N42S, which results in platelet dysfunction due to reduced surface expression. It is associated with a significant bleeding history in the patient in whom it was identified. This is the first description of a naturally occurring variant that results in the substitution of this highly conserved residue and confirms the importance of this residue for correct GPCR function.
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21
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Bastida JM, Lozano ML, Benito R, Janusz K, Palma-Barqueros V, Del Rey M, Hernández-Sánchez JM, Riesco S, Bermejo N, González-García H, Rodriguez-Alén A, Aguilar C, Sevivas T, López-Fernández MF, Marneth AE, van der Reijden BA, Morgan NV, Watson SP, Vicente V, Hernández-Rivas JM, Rivera J, González-Porras JR. Introducing high-throughput sequencing into mainstream genetic diagnosis practice in inherited platelet disorders. Haematologica 2017; 103:148-162. [PMID: 28983057 PMCID: PMC5777202 DOI: 10.3324/haematol.2017.171132] [Citation(s) in RCA: 86] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Accepted: 09/29/2017] [Indexed: 12/30/2022] Open
Abstract
Inherited platelet disorders are a heterogeneous group of rare diseases, caused by inherited defects in platelet production and/or function. Their genetic diagnosis would benefit clinical care, prognosis and preventative treatments. Until recently, this diagnosis has usually been performed via Sanger sequencing of a limited number of candidate genes. High-throughput sequencing is revolutionizing the genetic diagnosis of diseases, including bleeding disorders. We have designed a novel high-throughput sequencing platform to investigate the unknown molecular pathology in a cohort of 82 patients with inherited platelet disorders. Thirty-four (41.5%) patients presented with a phenotype strongly indicative of a particular type of platelet disorder. The other patients had clinical bleeding indicative of platelet dysfunction, but with no identifiable features. The high-throughput sequencing test enabled a molecular diagnosis in 70% of these patients. This sensitivity increased to 90% among patients suspected of having a defined platelet disorder. We found 57 different candidate variants in 28 genes, of which 70% had not previously been described. Following consensus guidelines, we qualified 68.4% and 26.3% of the candidate variants as being pathogenic and likely pathogenic, respectively. In addition to establishing definitive diagnoses of well-known inherited platelet disorders, high-throughput sequencing also identified rarer disorders such as sitosterolemia, filamin and actinin deficiencies, and G protein-coupled receptor defects. This included disease-causing variants in DIAPH1 (n=2) and RASGRP2 (n=3). Our study reinforces the feasibility of introducing high-throughput sequencing technology into the mainstream laboratory for the genetic diagnostic practice in inherited platelet disorders.
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Affiliation(s)
- José M Bastida
- Servicio de Hematología, Hospital Universitario de Salamanca-IBSAL-USAL, Spain .,On behalf of the Project "Functional and Molecular Characterization of Patients with Inherited Platelet Disorders" of the Hemorrhagic Diathesis Working Group of the Spanish Society of Thrombosis and Haemostasis
| | - María L Lozano
- Servicio de Hematología y Oncología Médica, Hospital Universitario Morales Meseguer, Centro Regional de Hemodonación, Universidad de Murcia, IMIB-Arrixaca, CB15/00055-CIBERER, Spain.,On behalf of the Project "Functional and Molecular Characterization of Patients with Inherited Platelet Disorders" of the Hemorrhagic Diathesis Working Group of the Spanish Society of Thrombosis and Haemostasis
| | - Rocío Benito
- IBSAL, IBMCC, CIC, Universidad de Salamanca-CSIC, Spain
| | - Kamila Janusz
- IBSAL, IBMCC, CIC, Universidad de Salamanca-CSIC, Spain
| | - Verónica Palma-Barqueros
- Servicio de Hematología y Oncología Médica, Hospital Universitario Morales Meseguer, Centro Regional de Hemodonación, Universidad de Murcia, IMIB-Arrixaca, CB15/00055-CIBERER, Spain
| | | | | | - Susana Riesco
- Servicio de Pediatría, Hospital Universitario de Salamanca-IBSAL, Spain
| | - Nuria Bermejo
- Servicio de Hematología, Complejo Hospitalario San Pedro Alcántara, Cáceres, Spain
| | | | - Agustín Rodriguez-Alén
- Servicio de Hematología y Hemoterapia, Hospital Virgen de la Salud, Complejo Hospitalario de Toledo, Spain
| | - Carlos Aguilar
- Servicio de Hematología, Complejo Asistencial de Soria, Spain
| | - Teresa Sevivas
- Serviço de Imunohemoterapia, Sangue e Medicina Transfusional do Centro Hospitalar e Universitário de Coimbra, EPE, Portugal
| | | | - Anna E Marneth
- Department of Laboratory Medicine, Laboratory of Hematology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Centre, Nijmegen, the Netherlands
| | - Bert A van der Reijden
- Department of Laboratory Medicine, Laboratory of Hematology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Centre, Nijmegen, the Netherlands
| | - Neil V Morgan
- Birmingham Platelet Group, Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, UK
| | - Steve P Watson
- Birmingham Platelet Group, Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, UK
| | - Vicente Vicente
- On behalf of the Project "Functional and Molecular Characterization of Patients with Inherited Platelet Disorders" of the Hemorrhagic Diathesis Working Group of the Spanish Society of Thrombosis and Haemostasis
| | - Jesús M Hernández-Rivas
- Servicio de Hematología, Hospital Universitario de Salamanca-IBSAL-USAL, Spain.,IBSAL, IBMCC, CIC, Universidad de Salamanca-CSIC, Spain
| | - José Rivera
- Servicio de Hematología y Oncología Médica, Hospital Universitario Morales Meseguer, Centro Regional de Hemodonación, Universidad de Murcia, IMIB-Arrixaca, CB15/00055-CIBERER, Spain.,On behalf of the Project "Functional and Molecular Characterization of Patients with Inherited Platelet Disorders" of the Hemorrhagic Diathesis Working Group of the Spanish Society of Thrombosis and Haemostasis
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22
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Al Ghaithi R, Drake S, Watson SP, Morgan NV, Harrison P. Comparison of multiple electrode aggregometry with lumi-aggregometry for the diagnosis of patients with mild bleeding disorders. J Thromb Haemost 2017; 15:2045-2052. [PMID: 28762630 DOI: 10.1111/jth.13784] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Indexed: 08/31/2023]
Abstract
Essentials There is a clinical need for new technologies to measure platelet function in whole blood. Mild bleeding disorders were evaluated using multiple electrode aggregometry (MEA). MEA is insensitive at detecting patients with mild platelet function and secretion defects. More studies are required to investigate MEA in patients with a defined set of platelet disorders. SUMMARY Background Multiple electrode aggregometry (MEA) measures changes in electrical impedance caused by platelet aggregation in whole blood. This approach is faster, more convenient and offers the advantage over light transmission aggregometry (LTA) of assessing platelet function in whole blood and reducing preanalytical errors associated with preparation of platelet-rich plasma (PRP). Several studies indicate the utility of this method in assessing platelet inhibition in individuals taking antiplatelet agents (e.g. aspirin and clopidogrel). Objective Our current study sought to evaluate the ability of MEA in diagnosing patients with mild bleeding disorders by comparison with light transmission lumi-aggregometry (lumi-LTA). Methods Forty healthy subjects and 109 patients with a clinical diagnosis of a mild bleeding disorder were recruited into the UK Genotyping and Phenotyping of Platelets study (GAPP, ISRCTN 77951167). MEA was performed on whole blood using one or two concentrations of ADP, PAR-1 peptide, arachidonic acid and collagen. Lumi-LTA was performed in PRP using several concentrations of ADP, adrenaline, arachidonic acid, collagen, PAR-1 peptide and ristocetin. Results Of 109 patients tested, 54 (49%) patients gave abnormal responses by lumi-LTA to one or more agonists. In contrast, only 16 (15%) patients were shown to have abnormal responses to one or more agonists by MEA. Conclusions In this study we showed that MEA is less sensitive in identifying patients with abnormal platelet function relative to lumi-LTA.
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Affiliation(s)
- R Al Ghaithi
- Institute of Inflammation and Ageing, University of Birmingham, Edgbaston, Birmingham, UK
- Institute of Cardiovascular Sciences University of Birmingham, University of Birmingham, Edgbaston, Birmingham, UK
| | - S Drake
- Institute of Cardiovascular Sciences University of Birmingham, University of Birmingham, Edgbaston, Birmingham, UK
| | - S P Watson
- Institute of Cardiovascular Sciences University of Birmingham, University of Birmingham, Edgbaston, Birmingham, UK
| | - N V Morgan
- Institute of Cardiovascular Sciences University of Birmingham, University of Birmingham, Edgbaston, Birmingham, UK
| | - P Harrison
- Institute of Inflammation and Ageing, University of Birmingham, Edgbaston, Birmingham, UK
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23
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Boknäs N, Ramström S, Faxälv L, Lindahl TL. Flow cytometry-based platelet function testing is predictive of symptom burden in a cohort of bleeders. Platelets 2017; 29:512-519. [PMID: 28895772 DOI: 10.1080/09537104.2017.1349305] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Platelet function disorders (PFDs) are common in patients with mild bleeding disorders (MBDs), yet the significance of laboratory findings suggestive of a PFD remain unclear due to the lack of evidence for a clinical correlation between the test results and the patient phenotype. Herein, we present the results from a study evaluating the potential utility of platelet function testing using whole-blood flow cytometry in a cohort of 105 patients undergoing investigation for MBD. Subjects were evaluated with a test panel comprising two different activation markers (fibrinogen binding and P-selectin exposure) and four physiologically relevant platelet agonists (ADP, PAR1-AP, PAR4-AP, and CRP-XL). Abnormal test results were identified by comparison with reference ranges constructed from 24 healthy controls or with the fifth percentile of the entire patient cohort. We found that the abnormal test results are predictive of bleeding symptom severity, and that the greatest predictive strength was achieved using a subset of the panel, comparing measurements of fibrinogen binding after activation with all four agonists with the fifth percentile of the patient cohort (p = 0.00008, hazard ratio 8.7; 95% CI 2.5-40). Our results suggest that whole-blood flow cytometry-based platelet function testing could become a feasible alternative for the investigation of MBDs. We also show that platelet function testing using whole-blood flow cytometry could provide a clinically relevant quantitative assessment of platelet-related hemostasis.
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Affiliation(s)
- Niklas Boknäs
- a Department of Hematology and Department of Clinical and Experimental Medicine , Linköping University , Linköping , Sweden
| | - Sofia Ramström
- b Department of Clinical Chemistry and Department of Clinical and Experimental Medicine , Linköping University , Linköping , Sweden.,c School of Medical Sciences , Örebro University , Örebro , Sweden
| | - Lars Faxälv
- d Department of Clinical and Experimental Medicine , Linköping University , Linköping , Sweden
| | - Tomas L Lindahl
- b Department of Clinical Chemistry and Department of Clinical and Experimental Medicine , Linköping University , Linköping , Sweden
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24
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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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25
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26
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Perez Botero J, Warad DM, He R, Uhl CB, Tian S, Otteson GE, Barness RL, Olson MC, Gossman SC, Charlesworth JE, Nichols WL, Pruthi RK, Chen D. Comprehensive Platelet Phenotypic Laboratory Testing and Bleeding History Scoring for Diagnosis of Suspected Hereditary Platelet Disorders. Am J Clin Pathol 2017; 148:23-32. [DOI: 10.1093/ajcp/aqx038] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
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27
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Practice patterns in the diagnosis of inherited platelet disorders within a single institution. Blood Coagul Fibrinolysis 2017; 28:303-308. [DOI: 10.1097/mbc.0000000000000596] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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28
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Badin MS, Iyer JK, Chong M, Graf L, Rivard GE, Waye JS, Paterson AD, Pare G, Hayward CPM. Molecular phenotype and bleeding risks of an inherited platelet disorder in a family with a RUNX1
frameshift mutation. Haemophilia 2017; 23:e204-e213. [DOI: 10.1111/hae.13169] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/01/2016] [Indexed: 12/21/2022]
Affiliation(s)
- M. S. Badin
- Department of Pathology and Molecular Medicine; McMaster University; Hamilton ON Canada
| | - J. K. Iyer
- Department of Pathology and Molecular Medicine; McMaster University; Hamilton ON Canada
| | - M. Chong
- Department of Pathology and Molecular Medicine; McMaster University; Hamilton ON Canada
| | - L. Graf
- Department of Pathology and Molecular Medicine; McMaster University; Hamilton ON Canada
| | - G. E. Rivard
- Hematology/Oncology; Centre Hospitalier Universitaire Sainte-Justine; Montreal QC Canada
| | - J. S. Waye
- Department of Pathology and Molecular Medicine; McMaster University; Hamilton ON Canada
| | - A. D. Paterson
- Genetics and Genome Biology; The Hospital for Sick Children; Toronto ON Canada
- The Dalla Lana School of Public Health and Institute of Medical Sciences; University of Toronto; Toronto ON Canada
| | - G. Pare
- Hamilton Regional Laboratory Medicine Program; Hamilton ON Canada
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29
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Bariana TK, Ouwehand WH, Guerrero JA, Gomez K. Dawning of the age of genomics for platelet granule disorders: improving insight, diagnosis and management. Br J Haematol 2016; 176:705-720. [PMID: 27984638 DOI: 10.1111/bjh.14471] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Inherited disorders of platelet granules are clinically heterogeneous and their prevalence is underestimated because most patients do not undergo a complete diagnostic work-up. The lack of a genetic diagnosis limits the ability to tailor management, screen family members, aid with family planning, predict clinical progression and detect serious consequences, such as myelofibrosis, lung fibrosis and malignancy, in a timely manner. This is set to change with the introduction of high throughput sequencing (HTS) as a routine clinical diagnostic test. HTS diagnostic tests are now available, affordable and allow parallel screening of DNA samples for variants in all of the 80 known bleeding, thrombotic and platelet genes. Increased genetic diagnosis and curation of variants is, in turn, improving our understanding of the pathobiology and clinical course of inherited platelet disorders. Our understanding of the genetic causes of platelet granule disorders and the regulation of granule biogenesis is a work in progress and has been significantly enhanced by recent genomic discoveries from high-powered genome-wide association studies and genome sequencing projects. In the era of whole genome and epigenome sequencing, new strategies are required to integrate multiple sources of big data in the search for elusive, novel genes underlying granule disorders.
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Affiliation(s)
- Tadbir K Bariana
- Katharine Dormandy Haemophilia Centre and Thrombosis Unit, Royal Free London NHS Foundation Trust, London, UK.,Department of Haematology, University College London Cancer Institute, London, UK.,Department of Haematology, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK
| | - Willem H Ouwehand
- Department of Haematology, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK.,NHS Blood and Transplant, Cambridge Biomedical Campus, Cambridge, UK.,NIHR BioResource, Cambridge University Hospitals, Cambridge Biomedical Campus, Cambridge, UK.,Human Genetics, Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, UK
| | - Jose A Guerrero
- Department of Haematology, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK.,NHS Blood and Transplant, Cambridge Biomedical Campus, Cambridge, UK
| | - Keith Gomez
- Katharine Dormandy Haemophilia Centre and Thrombosis Unit, Royal Free London NHS Foundation Trust, London, UK
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30
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Watson SP, Daly ME, Harrison P, Lowe GC, Paterson A, Rivera J, Warner TD, Morgan NV. ISTH Advanced Training Course on platelet bleeding disorders: How should they be investigated? St. Anne's College, Oxford, 6-9th September 2016. Platelets 2016; 27:719-721. [PMID: 27841701 DOI: 10.1080/09537104.2016.1256726] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Steve P Watson
- a Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham , Birmingham , UK
| | - Martina E Daly
- b Department of Infection , Immunity and Cardiovascular Disease, University of Sheffield , Sheffield , UK
| | - Paul Harrison
- c Institute of Inflammation and Ageing, College of Medical and Dental Sciences, University of Birmingham , Birmingham , UK
| | - Gillian C Lowe
- a Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham , Birmingham , UK.,d Haemophilia Comprehensive Care Centre, University Hospital Birmingham , Edgbaston , Birmingham , UK
| | - Andrew Paterson
- e Program in Genetics & Genomic Biology , The Hospital for Sick Children Research Institute , Toronto , Ontario , Canada
| | - Jose Rivera
- f Servicio de Hematología y Oncología Médica, Hospital Universitario Morales Meseguer, Centro Regional de Hemodonación, Universidad de Murcia , IMIB-Arrixaca, CIBERER, Murcia 30003 , Spain
| | - Tim D Warner
- g The William Harvey Research Institute, Barts & The London School of Medicine & Dentistry, Queen Mary University of London , London , UK
| | - Neil V Morgan
- a Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham , Birmingham , UK
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31
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Nance D, Campbell RA, Rowley JW, Downie JM, Jorde LB, Kahr WH, Mereby SA, Tolley ND, Zimmerman GA, Weyrich AS, Rondina MT. Combined variants in factor VIII and prostaglandin synthase-1 amplify hemorrhage severity across three generations of descendants. J Thromb Haemost 2016; 14:2230-2240. [PMID: 27629384 PMCID: PMC5501291 DOI: 10.1111/jth.13500] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Accepted: 07/08/2016] [Indexed: 01/05/2023]
Abstract
Essentials Co-existent damaging variants are likely to cause more severe bleeding and may go undiagnosed. We determined pathogenic variants in a three-generational pedigree with excessive bleeding. Bleeding occurred with concurrent variants in prostaglandin synthase-1 (PTGS-1) and factor VIII. The PTGS-1 variant was associated with functional defects in the arachidonic acid pathway. SUMMARY Background Inherited human variants that concurrently cause disorders of primary hemostasis and coagulation are uncommon. Nevertheless, rare cases of co-existent damaging variants are likely to cause more severe bleeding and may go undiagnosed. Objective We prospectively sought to determine pathogenic variants in a three-generational pedigree with excessive bleeding. Patients/methods Platelet number, size and light transmission aggregometry to multiple agonists were evaluated in pedigree members. Transmission electron microscopy determined platelet morphology and granule content. Thromboxane release studies and light transmission aggregometry in the presence or absence of prostaglandin G2 assessed specific functional defects in the arachidonic acid pathway. Whole exome sequencing (WES) and targeted nucleotide sequence analysis identified potentially deleterious variants. Results Pedigree members with excessive bleeding had impaired platelet aggregation with arachidonic acid, epinephrine and low-dose ADP, as well as reduced platelet thromboxane B2 release. Impaired platelet aggregation in response to 2MesADP was rescued with prostaglandin G2 , a prostaglandin intermediate downstream of prostaglandin synthase-1 (PTGS-1) that aids in the production of thromboxane. WES identified a non-synonymous variant in the signal peptide of PTGS-1 (rs3842787; c.50C>T; p.Pro17Leu) that completely co-segregated with disease phenotype. A variant in the F8 gene causing hemophilia A (rs28935203; c.5096A>T; p.Y1699F) was also identified. Individuals with both variants had more severe bleeding manifestations than characteristic of mild hemophilia A alone. Conclusion We provide the first report of co-existing variants in both F8 and PTGS-1 genes in a three-generation pedigree. The PTGS-1 variant was associated with specific functional defects in the arachidonic acid pathway and more severe hemorrhage.
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Affiliation(s)
- D Nance
- The Division of Hematology, University of Utah, Salt Lake City, UT, USA
| | - R A Campbell
- Molecular Medicine Program, University of Utah, Salt Lake City, UT, USA
| | - J W Rowley
- Molecular Medicine Program, University of Utah, Salt Lake City, UT, USA
- Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA
| | - J M Downie
- Department of Human Genetics, University of Utah, Salt Lake City, UT, USA
| | - L B Jorde
- Department of Human Genetics, University of Utah, Salt Lake City, UT, USA
| | - W H Kahr
- Department of Paediatrics, Division of Haematology/Oncology, University of Toronto, Toronto, ON, Canada
- Program in Cell Biology, Research Institute, Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | - S A Mereby
- Molecular Medicine Program, University of Utah, Salt Lake City, UT, USA
| | - N D Tolley
- Molecular Medicine Program, University of Utah, Salt Lake City, UT, USA
| | - G A Zimmerman
- Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA
| | - A S Weyrich
- Molecular Medicine Program, University of Utah, Salt Lake City, UT, USA
- Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA
| | - M T Rondina
- Molecular Medicine Program, University of Utah, Salt Lake City, UT, USA
- Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA
- GRECC, George E. Wahlen Salt Lake City VAMC, Salt Lake City, UT, USA
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32
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Abstract
Platelets have many functions within the haemostatic system, and when these actions are diminished for whatever reason, a bleeding tendency can manifest. Unravelling the reason(s) for this bleeding can be complex due to the multiple roles platelets perform. This review seeks to explain each level of platelet testing moving from those performed at local hospital laboratories to those performed by specialist centres and university research departments. It will examine the testing available and discuss when to move on to additional testing.
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Affiliation(s)
- David Gurney
- a Department of Haematology , University Hospital Bristol , Bristol , UK
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33
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Badin MS, Graf L, Iyer JK, Moffat KA, Seecharan JL, Hayward CPM. Variability in platelet dense granule adenosine triphosphate release findings amongst patients tested multiple times as part of an assessment for a bleeding disorder. Int J Lab Hematol 2016; 38:648-657. [PMID: 27571881 DOI: 10.1111/ijlh.12553] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2016] [Accepted: 06/07/2016] [Indexed: 10/21/2022]
Abstract
INTRODUCTION Lumi-aggregometry quantification of platelet dense granule adenosine triphosphate (ATP) release is commonly used for diagnosing platelet function disorders. As the test findings show considerable variability for healthy controls, we postulated that patient findings might also be variable and investigated patients who were assessed for dense granule ATP release defects more than once. METHODS Analyses were performed on prospectively collected data for first and second tests for subjects tested for dense granule ATP release defects more than once by the Hamilton Regional Laboratory Program (HRLMP) between January 2007 and June 2013 (cohort I). Similar analyses were performed for subjects who were recruited to a platelet disorder study (cohort II) and were assessed for ATP release defects more than once before October 2015. RESULTS A total of 150 unique subjects had multiple ATP release tests. Results with individual agonists were variable for many subjects. While normal findings with all tested agonists were often confirmed by the second test (cohort I: 83%; cohort II: 100%), impaired release with multiple agonists was confirmed in only some subjects (cohort I: 34%; cohort II: 54%). Inconsistent findings were common (cohort I: 36%; cohort II: 39%). ISTH bleeding scores showed no relationship to the test findings. The finding of impaired ATP release with 2 or more agonists on both tests was not associated with an increased likelihood of a definite bleeding disorder. CONCLUSION The variability in platelet dense granule ATP release findings amongst patients assessed for diagnostic purposes suggests that the test has limited value for diagnosing platelet disorders.
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Affiliation(s)
- M S Badin
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, Canada
| | - L Graf
- Centre for Laboratory Medicine and Hemophilia and Hemostasis Centre, St. Gallen, Switzerland
| | - J K Iyer
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, Canada
| | - K A Moffat
- Department of Medicine, McMaster University, Hamilton, ON, Canada.,Hamilton Regional Laboratory Medicine Program, Hamilton, ON, Canada
| | - J L Seecharan
- Hamilton Regional Laboratory Medicine Program, Hamilton, ON, Canada
| | - C P M Hayward
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, Canada.,Department of Medicine, McMaster University, Hamilton, ON, Canada.,Hamilton Regional Laboratory Medicine Program, Hamilton, ON, Canada
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Maclachlan A, Watson SP, Morgan NV. Inherited platelet disorders: Insight from platelet genomics using next-generation sequencing. Platelets 2016; 28:14-19. [PMID: 27348543 PMCID: PMC5359778 DOI: 10.1080/09537104.2016.1195492] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Inherited platelet disorders (IPDs) are a heterogeneous group of disorders associated with normal or reduced platelet counts and bleeding diatheses of varying severities. The identification of the underlying cause of IPDs is clinically challenging due to the absence of a gold-standard platelet test, and is often based on a clinical presentation and normal values in other hematology assays. As a consequence, a DNA-based approach has a potentially important role in the investigation of these patients. Next-generation sequencing (NGS) technologies are allowing the rapid analysis of genes that have been previously implicated in IPDs or that are known to have a key role in platelet regulation, as well as novel genes that have not been previously implicated in platelet dysfunction. The potential limitations of NGS arise with the interpretation of the sheer volume of genetic information obtained from whole exome sequencing (WES) or whole genome sequencing (WGS) in order to identify function-disrupting variants. Following on from bioinformatic analysis, a number of candidate genetic variants usually remain, therefore adding to the difficulty of phenotype–genotype segregation verification. Linking genetic changes to an underlying bleeding disorder is an ongoing challenge and may not always be feasible due to the multifactorial nature of IPDs. Nevertheless, NGS will play a key role in our understanding of the mechanisms of platelet function and the genetics involved.
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Affiliation(s)
- Annabel Maclachlan
- a Institute of Cardiovascular Sciences, College of Medical and Dental Sciences , University of Birmingham , Birmingham , B15 2TT , UK
| | - Steve P Watson
- a Institute of Cardiovascular Sciences, College of Medical and Dental Sciences , University of Birmingham , Birmingham , B15 2TT , UK
| | - Neil V Morgan
- a Institute of Cardiovascular Sciences, College of Medical and Dental Sciences , University of Birmingham , Birmingham , B15 2TT , UK
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Inherited platelet disorders: toward DNA-based diagnosis. Blood 2016; 127:2814-23. [PMID: 27095789 DOI: 10.1182/blood-2016-03-378588] [Citation(s) in RCA: 105] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Accepted: 04/13/2016] [Indexed: 12/11/2022] Open
Abstract
Variations in platelet number, volume, and function are largely genetically controlled, and many loci associated with platelet traits have been identified by genome-wide association studies (GWASs).(1) The genome also contains a large number of rare variants, of which a tiny fraction underlies the inherited diseases of humans. Research over the last 3 decades has led to the discovery of 51 genes harboring variants responsible for inherited platelet disorders (IPDs). However, the majority of patients with an IPD still do not receive a molecular diagnosis. Alongside the scientific interest, molecular or genetic diagnosis is important for patients. There is increasing recognition that a number of IPDs are associated with severe pathologies, including an increased risk of malignancy, and a definitive diagnosis can inform prognosis and care. In this review, we give an overview of these disorders grouped according to their effect on platelet biology and their clinical characteristics. We also discuss the challenge of identifying candidate genes and causal variants therein, how IPDs have been historically diagnosed, and how this is changing with the introduction of high-throughput sequencing. Finally, we describe how integration of large genomic, epigenomic, and phenotypic datasets, including whole genome sequencing data, GWASs, epigenomic profiling, protein-protein interaction networks, and standardized clinical phenotype coding, will drive the discovery of novel mechanisms of disease in the near future to improve patient diagnosis and management.
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Fletcher SJ, Johnson B, Lowe GC, Bem D, Drake S, Lordkipanidzé M, Guiú IS, Dawood B, Rivera J, Simpson MA, Daly ME, Motwani J, Collins PW, Watson SP, Morgan NV. SLFN14 mutations underlie thrombocytopenia with excessive bleeding and platelet secretion defects. J Clin Invest 2015; 125:3600-5. [PMID: 26280575 DOI: 10.1172/jci80347] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Accepted: 07/08/2015] [Indexed: 01/08/2023] Open
Abstract
Inherited thrombocytopenias are a group of disorders that are characterized by a low platelet count and are sometimes associated with excessive bleeding that ranges from mild to severe. We evaluated 36 unrelated patients and 17 family members displaying thrombocytopenia that were recruited to the UK Genotyping and Phenotyping of Platelets (GAPP) study. All patients had a history of excessive bleeding of unknown etiology. We performed platelet phenotyping and whole-exome sequencing (WES) on all patients and identified mutations in schlafen 14 (SLFN14) in 12 patients from 3 unrelated families. Patients harboring SLFN14 mutations displayed an analogous phenotype that consisted of moderate thrombocytopenia, enlarged platelets, decreased ATP secretion, and a dominant inheritance pattern. Three heterozygous missense mutations were identified in affected family members and predicted to encode substitutions (K218E, K219N, and V220D) within an ATPase-AAA-4, GTP/ATP-binding region of SLFN14. Endogenous SLFN14 expression was reduced in platelets from all patients, and mutant SLFN14 expression was markedly decreased compared with that of WT SLFN14 when overexpressed in transfected cells. Electron microscopy revealed a reduced number of dense granules in affected patients platelets, correlating with a decreased ATP secretion observed in lumiaggregometry studies. These results identify SLFN14 mutations as cause for an inherited thrombocytopenia with excessive bleeding, outlining a fundamental role for SLFN14 in platelet formation and function.
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Abstract
The gene variants responsible for the primary genotype of many platelet disorders have now been identified. Next-generation sequencing technology (NGST), mainly exome sequencing, has highlighted genes responsible for defects in platelet secretion (NBEAL2, gray platelet syndrome), procoagulant activity (STIM1, Stormorken syndrome), and activation pathways (RASGRP2, CalDAG-GEFI deficiency and integrin dysfunction; PRKACG, cyclic adenosine monophosphate-dependent protein kinase deficiency). Often disorders of platelet function are associated with a modified platelet production with changes in platelet number and size and can accompany malfunction of other organs or tissues. Most families have private mutations, and gene variants may prevent protein synthesis, abrogate function, or result in aberrant activated proteins. Nevertheless, bleeding severity is difficult to predict by genotype alone suggesting other factors. A major new challenge of NGST is to identify these factors and help improve patient care. This review concentrates on recent developments and is illustrated from personal observations.
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Affiliation(s)
- A T Nurden
- Institut de Rhythmologie et de Modélisation Cardiaque, Plateforme Technologique d'Innovation Biomédicale, Hôpital Xavier Arnozan, Pessac, France
| | - P Nurden
- Institut de Rhythmologie et de Modélisation Cardiaque, Plateforme Technologique d'Innovation Biomédicale, Hôpital Xavier Arnozan, Pessac, France
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Dovlatova N. Current status and future prospects for platelet function testing in the diagnosis of inherited bleeding disorders. Br J Haematol 2015; 170:150-61. [PMID: 25920378 DOI: 10.1111/bjh.13405] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Platelets play a crucial role in haemostasis by preventing bleeding at the site of vascular injury. Several defects in platelet morphology and function have been identified and described over the years. Although a range of methodologies is available to assess platelet function, a significant proportion of subjects with bleeding symptoms and normal coagulation parameters still appear to have normal results on platelet function testing. This might suggest that the reason for bleeding is multifactorial and is due to a combination of several minor defects in platelet function and/or other parts of the haemostatic system or might indicate that the currently available platelet function tests do not provide optimal diagnostic power. This review will summarize the established platelet function tests used for diagnosing inherited platelet abnormalities in adults and children, and discuss the newly developed methodologies as well as unmet challenges and potential areas for further improvement in this field.
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Affiliation(s)
- Natalia Dovlatova
- Division of Clinical Neuroscience, Thrombosis and Haemostasis Research Group, Queens Medical Centre, University of Nottingham, Nottingham, UK
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Leo VC, Morgan NV, Bem D, Jones ML, Lowe GC, Lordkipanidzé M, Drake S, Simpson MA, Gissen P, Mumford A, Watson SP, Daly ME. Use of next-generation sequencing and candidate gene analysis to identify underlying defects in patients with inherited platelet function disorders. J Thromb Haemost 2015; 13:643-50. [PMID: 25556537 PMCID: PMC4383639 DOI: 10.1111/jth.12836] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Accepted: 12/14/2014] [Indexed: 12/22/2022]
Abstract
BACKGROUND Inherited platelet function disorders (PFDs) are heterogeneous, and identification of the underlying genetic defects is difficult when based solely on phenotypic and clinical features of the patient. OBJECTIVE To analyze 329 genes regulating platelet function, number, and size in order to identify candidate gene defects in patients with PFDs. PATIENTS/METHODS Targeted analysis of candidate PFD genes was undertaken after next-generation sequencing of exomic DNA from 18 unrelated index cases with PFDs who were recruited into the UK Genotyping and Phenotyping of Platelets (GAPP) study and diagnosed with platelet abnormalities affecting either Gi signaling (n = 12) or secretion (n = 6). The potential pathogenicity of candidate gene defects was assessed using computational predictive algorithms. RESULTS Analysis of the 329 candidate PFD genes identified 63 candidate defects, affecting 40 genes, among index cases with Gi signaling abnormalities, while 53 defects, within 49 genes, were identified among patients with secretion abnormalities. Homozygous gene defects were more commonly associated with secretion abnormalities. Functional annotation analysis identified distinct gene clusters in the two patient subgroups. Thirteen genes with significant annotation enrichment for 'intracellular signaling' harbored 16 of the candidate gene defects identified in nine index cases with Gi signaling abnormalities. Four gene clusters, representing 14 genes, with significantly associated gene ontology annotations were identified among the cases with secretion abnormalities, the most significant association being with 'establishment of protein localization.' CONCLUSION Our findings demonstrate the genetic complexity of PFDs and highlight plausible candidate genes for targeted analysis in patients with platelet secretion and Gi signaling abnormalities.
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Affiliation(s)
- V C Leo
- Department of Cardiovascular Science, University of Sheffield Medical School, University of Sheffield, Sheffield, UK
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Goodeve AC, Pavlova A, Oldenburg J. Genomics of bleeding disorders. Haemophilia 2014; 20 Suppl 4:50-3. [PMID: 24762275 DOI: 10.1111/hae.12424] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/05/2014] [Indexed: 11/28/2022]
Abstract
Molecular genetic tools are widely applied in inherited bleeding disorders. New genes involved in haemorrhagic disorders have been identified by genome wide linkage analysis on families with a specific phenotype. LMNA1 or MCFD in combined FV/FVIII-deficiency and VKORC1 in vitamin K coagulation factor deficiency type 2 are two examples. Identification of the causative gene mutation has become standard for most bleeding disorders. Knowledge of the causative mutation allows genetic counselling in affected families and most importantly adds to the pathophysiological understanding of phenotypes. Haemophilia A represents a model as the F8 gene mutation predicts the risk of developing an inhibitor and more recently also the bleeding phenotype. In this review novel genetic diagnostic strategies for bleeding disorders are outlined and inhibitor formation is presented as an example for clinical relevant phenotype/genotype correlation studies.
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Affiliation(s)
- A C Goodeve
- Sheffield Diagnostic Genetics Service, Sheffield Children's NHS Foundation Trust and Haemostasis Research Group, Department of Cardiovascular Science, University of Sheffield, Sheffield, UK
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Favaloro EJ, Bodó I, Israels SJ, Brown SA. von Willebrand disease and platelet disorders. Haemophilia 2014; 20 Suppl 4:59-64. [PMID: 24762277 DOI: 10.1111/hae.12414] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/24/2014] [Indexed: 01/24/2023]
Abstract
The diagnosis and management of bleeding disorders is made difficult by the complexity and variety of disorders, clinical symptoms and bleeding type and severity. von Willebrand disease (VWD) and platelet disorders are disorders of primary haemostasis and together represent the most common inherited bleeding disorders. In this article, we describe the diagnosis of VWD and platelet disorders and the treatment options for VWD.
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Affiliation(s)
- E J Favaloro
- Diagnostic Haemostasis, Haematology Department, Institute of Clinical Pathology and Medical Research (ICPMR), Pathology West, Westmead Hospital, Westmead, NSW, Australia
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Nisar SP, Jones ML, Cunningham MR, Mumford AD, Mundell SJ. Rare platelet GPCR variants: what can we learn? Br J Pharmacol 2014; 172:3242-53. [PMID: 25231155 DOI: 10.1111/bph.12941] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Revised: 09/05/2014] [Accepted: 09/09/2014] [Indexed: 12/31/2022] Open
Abstract
Platelet-expressed GPCRs are critical regulators of platelet function. Pharmacological blockade of these receptors forms a powerful therapeutic tool in the treatment and prevention of arterial thrombosis associated with coronary atherosclerosis and ischaemic stroke. However, anti-thrombotic drug therapy is associated with high inter-patient variability in therapeutic response and adverse bleeding side effects. In order to optimize the use of existing anti-platelet drugs and to develop new therapies, more detailed knowledge is required relating to the molecular mechanisms that regulate GPCR and therefore platelet function. One approach has been to identify rare, function-disrupting mutations within key platelet proteins in patients with bleeding disorders. In this review, we describe how an integrated functional genomics strategy has contributed important structure-function information about platelet GPCRs with specific emphasis upon purinergic and thromboxane A2 receptors. We also discuss the potential implications these findings have for pharmacotherapy and for understanding the molecular basis of mild bleeding disorders.
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Affiliation(s)
- S P Nisar
- School of Physiology and Pharmacology, University of Bristol, Bristol, UK
| | - M L Jones
- School of Cellular and Molecular Medicine, University of Bristol, Bristol, UK
| | - M R Cunningham
- School of Physiology and Pharmacology, University of Bristol, Bristol, UK
| | - A D Mumford
- School of Cellular and Molecular Medicine, University of Bristol, Bristol, UK
| | - S J Mundell
- School of Physiology and Pharmacology, University of Bristol, Bristol, UK
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Burkhart JM, Gambaryan S, Watson SP, Jurk K, Walter U, Sickmann A, Heemskerk JWM, Zahedi RP. What can proteomics tell us about platelets? Circ Res 2014; 114:1204-19. [PMID: 24677239 DOI: 10.1161/circresaha.114.301598] [Citation(s) in RCA: 81] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
More than 130 years ago, it was recognized that platelets are key mediators of hemostasis. Nowadays, it is established that platelets participate in additional physiological processes and contribute to the genesis and progression of cardiovascular diseases. Recent data indicate that the platelet proteome, defined as the complete set of expressed proteins, comprises >5000 proteins and is highly similar between different healthy individuals. Owing to their anucleate nature, platelets have limited protein synthesis. By implication, in patients experiencing platelet disorders, platelet (dys)function is almost completely attributable to alterations in protein expression and dynamic differences in post-translational modifications. Modern platelet proteomics approaches can reveal (1) quantitative changes in the abundance of thousands of proteins, (2) post-translational modifications, (3) protein-protein interactions, and (4) protein localization, while requiring only small blood donations in the range of a few milliliters. Consequently, platelet proteomics will represent an invaluable tool for characterizing the fundamental processes that affect platelet homeostasis and thus determine the roles of platelets in health and disease. In this article we provide a critical overview on the achievements, the current possibilities, and the future perspectives of platelet proteomics to study patients experiencing cardiovascular, inflammatory, and bleeding disorders.
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Affiliation(s)
- Julia M Burkhart
- From the Leibniz-Institut für Analytische Wissenschaften-ISAS-e.V., Dortmund, Germany (J.M.B., A.S., R.P.Z); Institut für Klinische Biochemie und Pathobiochemie, Universitätsklinikum Würzburg, Würzburg, Germany (S.G.); Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, St. Petersburg, Russia (S.G.); Centre for Cardiovascular Sciences, Institute for Biomedical Research, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom (S.P.W.); Center for Thrombosis and Hemostasis, Universitätsklinikum der Johannes Gutenberg-Universität Mainz, Mainz, Germany (K.J., U.W.); Medizinisches Proteom Center, Ruhr Universität Bochum, Bochum, Germany (A.S.); Department of Chemistry, College of Physical Sciences, University of Aberdeen, Aberdeen, Scotland, United Kingdom (A.S.); and Department of Biochemistry, CARIM, Maastricht University, Maastricht, The Netherlands (J.W.M.H.)
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Dovlatova N, Lordkipanidzé M, Lowe GC, Dawood B, May J, Heptinstall S, Watson SP, Fox SC. Evaluation of a whole blood remote platelet function test for the diagnosis of mild bleeding disorders. J Thromb Haemost 2014; 12:660-5. [PMID: 24618131 PMCID: PMC4405765 DOI: 10.1111/jth.12555] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Accepted: 02/23/2014] [Indexed: 11/28/2022]
Abstract
BACKGROUND Mild platelet function disorders (PFDs) are complex and difficult to diagnose. The current gold standard test, light transmission aggregometry (LTA), including lumi-aggregometry, is time and labour intensive and blood samples must be processed within a limited time after venepuncture. Furthermore, many subjects with suspected PFDs do not show a platelet abnormality on LTA. OBJECTIVE To assess the diagnostic potential of an easy-to-use remote platelet function test (RPFT) as a diagnostic pre-test for suspected PFDs. METHODS A remote platelet function test was compared with lumi-aggregometry in participants recruited to the Genotyping and Phenotyping of Platelets Study (GAPP, ISRCTN 77951167). For the RPFT, whole blood was stimulated with platelet agonists, stabilized with PAMFix and returned to the central laboratory for analysis of P-selectin and CD63 by flow cytometry. RESULTS For the 61 study participants (42 index cases and 19 relatives) there was a good agreement between lumi-aggregometry and the RPFT, with diagnosis being concordant in 84% of cases (κ = 0.668, P < 0.0001). According to both tests, 29 participants were identified to have a deficiency in platelet function and 22 participants appeared normal. There were four participants where lumi-aggregometry revealed a defect but the RPFT did not, and six participants where the RPFT detected an abnormal platelet response that was not identified by lumi-aggregometry. CONCLUSION This study suggests that the RPFT could be an easy-to-use pre-test to select which participants with bleeding disorders would benefit from extensive platelet phenotyping. Further development and evaluation of the test are warranted in a wider population of patients with excessive bleeding and could provide informative screening tests for PFDs.
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Affiliation(s)
- Natalia Dovlatova
- Cardiovascular Medicine, University of Nottingham, Queens Medical Centre, Nottingham, United Kingdom
- Centre for Cardiovascular Sciences, Birmingham Platelet Group, University of Birmingham, Birmingham, United Kingdom
| | - Marie Lordkipanidzé
- Centre for Cardiovascular Sciences, Birmingham Platelet Group, University of Birmingham, Birmingham, United Kingdom
| | - Gillian C. Lowe
- Centre for Cardiovascular Sciences, Birmingham Platelet Group, University of Birmingham, Birmingham, United Kingdom
| | - Ban Dawood
- Centre for Cardiovascular Sciences, Birmingham Platelet Group, University of Birmingham, Birmingham, United Kingdom
| | - Jane May
- Cardiovascular Medicine, University of Nottingham, Queens Medical Centre, Nottingham, United Kingdom
| | - Stan Heptinstall
- Cardiovascular Medicine, University of Nottingham, Queens Medical Centre, Nottingham, United Kingdom
| | - Steve P. Watson
- Centre for Cardiovascular Sciences, Birmingham Platelet Group, University of Birmingham, Birmingham, United Kingdom
| | - Susan C. Fox
- Cardiovascular Medicine, University of Nottingham, Queens Medical Centre, Nottingham, United Kingdom
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Daly ME, Leo VC, Lowe GC, Watson SP, Morgan NV. What is the role of genetic testing in the investigation of patients with suspected platelet function disorders? Br J Haematol 2014; 165:193-203. [DOI: 10.1111/bjh.12751] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Martina E. Daly
- Department of Cardiovascular Science; University of Sheffield Medical School; University of Sheffield; Sheffield UK
| | - Vincenzo C. Leo
- Department of Cardiovascular Science; University of Sheffield Medical School; University of Sheffield; Sheffield UK
| | - Gillian C. Lowe
- Centre for Cardiovascular Sciences; School of Clinical and Experimental Medicine; College of Medical and Dental Sciences; University of Birmingham; Birmingham UK
| | - Steve P. Watson
- Centre for Cardiovascular Sciences; School of Clinical and Experimental Medicine; College of Medical and Dental Sciences; University of Birmingham; Birmingham UK
| | - Neil V. Morgan
- Centre for Cardiovascular Sciences; School of Clinical and Experimental Medicine; College of Medical and Dental Sciences; University of Birmingham; Birmingham UK
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Characterization of multiple platelet activation pathways in patients with bleeding as a high-throughput screening option: use of 96-well Optimul assay. Blood 2014; 123:e11-22. [PMID: 24408324 DOI: 10.1182/blood-2013-08-520387] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Up to 1% of the population have mild bleeding disorders, but these remain poorly characterized, particularly with regard to the roles of platelets. We have compared the usefulness of Optimul, a 96-well plate-based assay of 7 distinct pathways of platelet activation to characterize inherited platelet defects in comparison with light transmission aggregometry (LTA). Using Optimul and LTA, concentration-response curves were generated for arachidonic acid, ADP, collagen, epinephrine, Thrombin receptor activating-peptide, U46619, and ristocetin in samples from (1) healthy volunteers (n = 50), (2) healthy volunteers treated with antiplatelet agents in vitro (n = 10), and (3) patients with bleeding of unknown origin (n = 65). The assays gave concordant results in 82% of cases (κ = 0.62, P < .0001). Normal platelet function results were particularly predictive (sensitivity, 94%; negative predictive value, 91%), whereas a positive result was not always substantiated by LTA (specificity, 67%; positive predictive value, 77%). The Optimul assay was significantly more sensitive at characterizing defects in the thromboxane pathway, which presented with normal responses with LTA. The Optimul assay is sensitive to mild platelet defects, could be used as a rapid screening assay in patients presenting with bleeding symptoms, and detects changes in platelet function more readily than LTA. This trial was registered at www.isrctn.org as #ISRCTN 77951167.
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Abstract
Platelet function tests have been traditionally used to aid in the diagnosis and management of patients with bleeding problems. Given the role of platelets in atherothrombosis, several dedicated platelet function instruments are now available that are simple to use and can be used as point-of-care assays. These can provide rapid assessment of platelet function within whole blood without the requirement of sample processing. Some tests can be used to monitor antiplatelet therapy and assess risk of bleeding and thrombosis, although current guidelines advise against this. This article discusses the potential utility of tests/instruments that are available.
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Affiliation(s)
- Paul Harrison
- School of Immunity and Infection, University of Birmingham Medical School, Birmingham, UK.
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50
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Stockley J, Morgan NV, Bem D, Lowe GC, Lordkipanidzé M, Dawood B, Simpson MA, Macfarlane K, Horner K, Leo VC, Talks K, Motwani J, Wilde JT, Collins PW, Makris M, Watson SP, Daly ME. Enrichment of FLI1 and RUNX1 mutations in families with excessive bleeding and platelet dense granule secretion defects. Blood 2013; 122:4090-3. [PMID: 24100448 PMCID: PMC3862284 DOI: 10.1182/blood-2013-06-506873] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2013] [Accepted: 09/18/2013] [Indexed: 11/20/2022] Open
Abstract
We analyzed candidate platelet function disorder genes in 13 index cases with a history of excessive bleeding in association with a significant reduction in dense granule secretion and impaired aggregation to a panel of platelet agonists. Five of the index cases also had mild thrombocytopenia. Heterozygous alterations in FLI1 and RUNX1, encoding Friend leukemia integration 1 and RUNT-related transcription factor 1, respectively, which have a fundamental role in megakaryocytopoeisis, were identified in 6 patients, 4 of whom had mild thrombocytopenia. Two FLI1 alterations predicting p.Arg337Trp and p.Tyr343Cys substitutions in the FLI1 DNA-binding domain abolished transcriptional activity of FLI1. A 4-bp deletion in FLI1, and 2 splicing alterations and a nonsense variation in RUNX1, which were predicted to cause haploinsufficiency of either FLI1 or RUNX1, were also identified. Our findings suggest that alterations in FLI1 and RUNX1 may be common in patients with platelet dense granule secretion defects and mild thrombocytopenia.
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Affiliation(s)
- Jacqueline Stockley
- Department of Cardiovascular Science, University of Sheffield Medical School, University of Sheffield, Sheffield, United Kingdom
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