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Strauss G, Mott K, Klopocki E, Schulze H. Thrombocytopenia Absent Radius (TAR)-Syndrome: From Current Genetics to Patient Self-Empowerment. Hamostaseologie 2023; 43:252-260. [PMID: 37611607 DOI: 10.1055/a-2088-1801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/25/2023] Open
Abstract
Thrombocytopenia absent radius (TAR) syndrome is a rare form of hereditary thrombocytopenia associated with a bilateral radial aplasia. TAR syndrome is genetically defined by the combination of a microdeletion on chromosome 1 which includes the gene RBM8A, and a single nucleotide polymorphism (SNP) in the second RBM8A allele. While most patients with TAR syndrome harbor a SNP in either the 5' UTR region or in intron 1 of RBM8A, further SNPs associated with TAR syndrome are still being identified. Here, we report on the current understanding of the genetic basis, diagnosis, and therapy of TAR syndrome and discuss patient self-empowerment by enabling networking and exchange between affected individuals and families.
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Affiliation(s)
- Gabriele Strauss
- Department of Paediatric Haematology and Oncology, Helios-Klinikum Buch, Berlin, Germany
| | - Kristina Mott
- Institute of Experimental Biomedicine I, University Hospital Würzburg, Würzburg, Germany
| | - Eva Klopocki
- Institute of Human Genetics, University of Würzburg, Würzburg, Germany
| | - Harald Schulze
- Institute of Experimental Biomedicine I, University Hospital Würzburg, Würzburg, Germany
- Center for Rare Blood Cell Disorders, Center for Rare Diseases, University Hospital Würzburg, Würzburg, Germany
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Manukjan G, Bösing H, Schmugge M, Strauß G, Schulze H. Impact of genetic variants on haematopoiesis in patients with thrombocytopenia absent radii (TAR) syndrome. Br J Haematol 2017; 179:606-617. [DOI: 10.1111/bjh.14913] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Accepted: 07/23/2017] [Indexed: 01/31/2023]
Affiliation(s)
- Georgi Manukjan
- Institute of Experimental Biomedicine, Chair I; University Hospital Würzburg; Würzburg Germany
| | - Hendrik Bösing
- Institute of Experimental Biomedicine, Chair I; University Hospital Würzburg; Würzburg Germany
- Laboratory of Paediatric Molecular Biology; Charité - University Hospital Berlin; Berlin Germany
| | | | - Gabriele Strauß
- Department of Paediatric Haematology and Oncology; Helios-Klinikum Buch; Berlin Germany
| | - Harald Schulze
- Institute of Experimental Biomedicine, Chair I; University Hospital Würzburg; Würzburg Germany
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Rao AK. Inherited platelet function disorders: overview and disorders of granules, secretion, and signal transduction. Hematol Oncol Clin North Am 2013; 27:585-611. [PMID: 23714313 DOI: 10.1016/j.hoc.2013.02.005] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Inherited disorders of platelet function are characterized by highly variable mucocutaneous bleeding manifestations. The platelet dysfunction arises by diverse mechanisms, including abnormalities in platelet membrane glycoproteins, granules and their contents, platelet signaling and secretion mechanisms: thromboxane production pathways and in platelet procoagulant activities. Platelet aggregation and secretion studies using platelet-rich plasma currently form the primary basis for the diagnosis of an inherited platelet dysfunction. In most such patients, the molecular and genetic mechanisms are unknown. Management of these patients needs to be individualized; therapeutic options include platelet transfusions, 1-desamino-8d-arginine vasopressin (DDAVP), recombinant factor VIIa, and antifibrinolytic agents.
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Affiliation(s)
- A Koneti Rao
- Hematology Section, Department of Medicine and Sol Sherry Thrombosis Research Center, Temple University School of Medicine, Philadelphia, PA 19140, USA.
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Albers CA, Newbury-Ecob R, Ouwehand WH, Ghevaert C. New insights into the genetic basis of TAR (thrombocytopenia-absent radii) syndrome. Curr Opin Genet Dev 2013; 23:316-23. [PMID: 23602329 DOI: 10.1016/j.gde.2013.02.015] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2012] [Revised: 02/15/2013] [Accepted: 02/25/2013] [Indexed: 12/31/2022]
Abstract
Thrombocytopenia with absent radii (TAR) syndrome is a rare disorder combining specific skeletal abnormalities with a reduced platelet count. Rare proximal microdeletions of 1q21.1 are found in the majority of patients but are also found in unaffected parents. Recently it was shown that TAR syndrome is caused by the compound inheritance of a low-frequency noncoding SNP and a rare null allele in RBM8A, a gene encoding the exon-junction complex subunit member Y14 located in the deleted region. This finding provides new insight into the complex inheritance pattern and new clues to the molecular mechanisms underlying TAR syndrome. We discuss TAR syndrome in the context of abnormal phenotypes associated with proximal and distal 1q21.1 microdeletion and microduplications with incomplete penetrance and variable expressivity.
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Geddis AE. Inherited thrombocytopenias: an approach to diagnosis and management. Int J Lab Hematol 2012; 35:14-25. [DOI: 10.1111/j.1751-553x.2012.01454.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2012] [Accepted: 06/12/2012] [Indexed: 01/19/2023]
Affiliation(s)
- A. E. Geddis
- Rady Children's Hospital San Diego; University of California San Diego; San Diego; CA; USA
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Autoimmune lymphoproliferative syndrome due to FAS mutations outside the signal-transducing death domain: molecular mechanisms and clinical penetrance. Genet Med 2011; 14:81-9. [PMID: 22237435 DOI: 10.1038/gim.0b013e3182310b7d] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
PURPOSE Autoimmune lymphoproliferative syndrome is a disorder of lymphocyte apoptosis. Although FAS molecules bearing mutations in the signal-transducing intracellular death domain exhibit dominant-negative interference with FAS-mediated apoptosis, mechanisms for pathology of non-death domain FAS mutations causing autoimmune lymphoproliferative syndrome are poorly defined. METHODS RNA stability, protein expression, ligand binding, and ability to transmit apoptosis signals by anti-FAS antibody or FAS ligand were determined for a cohort of 39 patients with non-death domain autoimmune lymphoproliferative syndrome. Correlations between mutation type and disease penetrance were established in mutation-positive family members. RESULTS Frameshifts or transcriptional stop mutations before exon 7 resulted in messenger RNA haploinsufficiency, whereas an amino-terminal signal sequence mutation and certain intracellular truncations prevented cell surface localization of FAS. All resulted in decreased FAS localization, inability to bind FAS ligand, and reduced FAS ligand-induced apoptosis. Extracellular missense mutations and in-frame deletions expressed defective FAS protein, failed to bind FAS ligand, and exhibited dominant-negative interference with FAS-mediated apoptosis. Mutation-positive relatives with haploinsufficient or extracellular mutations had lower penetrance of autoimmune lymphoproliferative syndrome clinical phenotypes than did relatives with death domain mutations. CONCLUSION We have defined molecular mechanisms by which non-death domain FAS mutations result in reduced lymphocyte apoptosis, established a hierarchy of genotype-phenotype correlation among mutation-positive relatives of patients with autoimmune lymphoproliferative syndrome, and demonstrated that FAS haploinsufficiency can lead to autoimmune lymphoproliferative syndrome.
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Fiedler J, Strauss G, Wannack M, Schwiebert S, Seidel K, Henning K, Klopocki E, Schmugge M, Gaedicke G, Schulze H. Two patterns of thrombopoietin signaling suggest no coupling between platelet production and thrombopoietin reactivity in thrombocytopenia-absent radii syndrome. Haematologica 2011; 97:73-81. [PMID: 21933853 DOI: 10.3324/haematol.2011.049619] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND Thrombocytopenia with absent radii syndrome is defined by bilateral radius aplasia and thrombocytopenia. Due to impaired thrombopoietin signaling there are only few bone marrow megakaryocytes and these are immature; the resulting platelet production defect improves somewhat over time. A microdeletion on chromosome 1q21 is present in all patients but is not sufficient to form thrombocytopenia with absent radii syndrome. We aimed to refine the signaling defect in this syndrome. DESIGN AND METHODS We report an extended study of 23 pediatric and adult patients suffering from thrombocytopenia with absent radii syndrome in order to scrutinize thrombopoietin signal transduction by immunoblotting and gel electrophoretic shift assays. In addition, platelet immunotyping and reactivity were analyzed by flow cytometry. Results were correlated with clinical data including age and platelet counts. RESULTS Two distinct signaling patterns were identified. Juvenile patients showed abrogated thrombopoietin signaling (pattern #1), which is restored in adults (pattern #2). Phosphorylated Jak2 was indicative of activation of STAT1, 3 and 5, Tyk2, ERK, and Akt, showing its pivotal role in distinct thrombopoietin-dependent pathways. Jak2 cDNA was not mutated and the thrombopoietin receptor was present on platelets. All platelets of patients expressed normal levels of CD41/61, CD49b, and CD49f receptors, while CD42a/b and CD29 were slightly reduced and the fibronectin receptor CD49e markedly reduced. Lysosomal granule release in response to thrombin receptor activating peptide was diminished. CONCLUSIONS We show a combined defect of platelet production and function in thrombocytopenia with absent radii syndrome. The rise in platelets that most patients have during the first years of life preceded the restored thrombopoietin signaling detected at a much later age, implying that these events are uncoupled and that an unknown factor mediates the improvement of platelet production.
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Houeijeh A, Andrieux J, Saugier-Veber P, David A, Goldenberg A, Bonneau D, Fouassier M, Journel H, Martinovic J, Escande F, Devisme L, Bisiaux S, Chaffiotte C, Baux M, Kerckaert JP, Holder-Espinasse M, Manouvrier-Hanu S. Thrombocytopenia-absent radius (TAR) syndrome: a clinical genetic series of 14 further cases. impact of the associated 1q21.1 deletion on the genetic counselling. Eur J Med Genet 2011; 54:e471-7. [PMID: 21635976 DOI: 10.1016/j.ejmg.2011.05.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2010] [Accepted: 05/03/2011] [Indexed: 10/18/2022]
Abstract
Thrombocytopenia-absent radius Syndrome (TAR) is a rare congenital malformation syndrome of complicated transmission. 1q21.1 deletion is necessary but not sufficient for its expression. We report the result of a French multicentric clinical study, and we emphasized on the role of the associated 1q21.1 deletion in the diagnosis and the genetic counselling of our patients. We gathered information on 14 patients presenting with TAR syndrome and referred for genetic counselling in six different university hospitals (8 foetuses, 1 child and 5 adults). Clinical or pathology details, as well as skeletal X-rays were analyzed. Genetic studies were performed by Array-CGH, and Quantitative Multiplex PCR. We demonstrated the very variable phenotypes of TAR syndrome. Female:male ratio was ∼2:1. All patients presented with bilateral radial aplasia/hypoplasia with preserved thumbs. Phocomelia and lower limb anomalies were present in 28% of the cases. We reported the first case of cystic hygroma on affected foetus. 1q21.1 deletions ranging from 330 to 1100 kb were identified in all affected patients. Most of them were inherited from one healthy parent (80%). The identification of a 1q21.1 deletion allowed confirmation of TAR syndrome diagnosis, particularly in foetuses and in atypical phenotypes. Additionally, it allowed accurate genetic counselling, especially when it occurred de novo. These findings allowed discussing the diagnostic criteria and management towards TAR syndrome.
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Affiliation(s)
- Ali Houeijeh
- Service de Génétique clinique Guy Fontaine, CHRU Lille, France
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Al-Qahtani FS. Congenital amegakaryocytic thrombocytopenia: a brief review of the literature. Clin Med Insights Pathol 2010; 3:25-30. [PMID: 21151552 PMCID: PMC2999995 DOI: 10.4137/cpath.s4972] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Congenital amegakaryocytic thrombocytopenia (CAMT) is a rare inherited autosomal recessive disorder that presents with thrombocytopenia and absence of megakaryocytes. It presents with bleeding recognized on day 1 of life or at least within the first month. The cause for this disorder appears to be a mutation in the gene for the thrombopoeitin (TPO) receptor, c-Mpl, despite high levels of serum TPO. Patients with severe Type I-CAMT carry nonsense Mpl mutations which causes a complete loss of the TPO receptor whereas those with Type II CAMT carry missense mutations in the Mpl gene affecting the extracellular domain of the TPO receptor. Differential diagnosis for severe CAMT includes thrombocytopenia with absent radii (TAR) and Wiskott-Aldrich syndrome (WAS). The primary treatment for CAMT is bone marrow transplantation. Bone Marrow/Stem Cell Transplant (HSCT) is the only thing that ultimately cures this genetic disease. Newer modalities are on the way, such as TPO-mimetics for binding towards partially functioning c-Mpl receptors and gene therapy. Prognosis of CAMT patients is poor, because all develop in childhood a tri-linear marrow aplasia that is always fatal when untreated. Thirty percent of patients with CAMT die due to bleeding complications and 20% -due to HSCT if it has been done.
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Affiliation(s)
- Fatma S. Al-Qahtani
- Division of Hematology, Department of Pathology. King Khalid University Hospital. King Saud University Riyadh, Kingdom of Saudi Arabia
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Geddis AE. Congenital amegakaryocytic thrombocytopenia and thrombocytopenia with absent radii. Hematol Oncol Clin North Am 2009; 23:321-31. [PMID: 19327586 DOI: 10.1016/j.hoc.2009.01.012] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Thrombocytopenia is a relatively common clinical problem in hospitalized neonates, and it is critical to distinguish infants who have rare congenital thrombocytopenias from those who have acquired disorders. Two well-described inherited thrombocytopenia syndromes that present in the newborn period are congenital amegakaryocytic thrombocytopenia (CAMT) and thrombocytopenia with absent radii (TAR). Although both are characterized by severe (< 50,000/microL) thrombocytopenia at birth, the molecular mechanisms underlying these disorders and their clinical presentations and courses are distinct. CAMT is an autosomal recessive disorder caused by mutations in the thrombopoietin (TPO) receptor c-Mpl. TAR is a syndrome of variable inheritance and unclear genetic etiology consisting of thrombocytopenia in association with bilateral absent radii and frequently additional congenital abnormalities. This article summarizes the current understanding of the pathophysiology and clinical course of CAMT and TAR.
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Affiliation(s)
- Amy E Geddis
- Department of Pediatrics, University of California San Diego, Rady Children's Hospital, 9500 Gilman Dr., Mailcode 0671, San Diego, CA 92093, USA.
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Thrombocytopenia with absent radii (TAR) syndrome: from hemopoietic progenitor to mesenchymal stromal cell disease? Exp Hematol 2009; 37:1-7. [DOI: 10.1016/j.exphem.2008.09.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2008] [Revised: 09/03/2008] [Accepted: 09/04/2008] [Indexed: 11/16/2022]
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12
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Garzon MC, Huang JT, Enjolras O, Frieden IJ. Vascular malformations. Part II: associated syndromes. J Am Acad Dermatol 2007; 56:541-64. [PMID: 17367610 DOI: 10.1016/j.jaad.2006.05.066] [Citation(s) in RCA: 115] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2006] [Revised: 05/18/2006] [Accepted: 05/24/2006] [Indexed: 01/19/2023]
Abstract
UNLABELLED Cutaneous vascular malformations are rare disorders representing errors in vascular development. These lesions occur much less commonly but are often confused with the common infantile hemangioma. It is important to properly diagnose vascular malformations because of their distinct differences in morbidity, prognosis and treatment. Vascular malformations may be associated with underlying disease or systemic anomalies. Several of these syndromes are well defined and can often be distinguished on the basis of the flow characteristics of the associated vascular malformation. LEARNING OBJECTIVE At the completion of this learning activity, participants should be able to better recognize underlying diseases or systemic anomalies that may be associated with vascular malformations. Participants should also better understand the various syndromes and conditions discussed and become more familiar with their management.
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Affiliation(s)
- Maria C Garzon
- Department of Dermatology, Columbia University, New York, NY 10032, USA.
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Klopocki E, Schulze H, Strauss G, Ott CE, Hall J, Trotier F, Fleischhauer S, Greenhalgh L, Newbury-Ecob RA, Neumann LM, Habenicht R, König R, Seemanova E, Megarbane A, Ropers HH, Ullmann R, Horn D, Mundlos S. Complex inheritance pattern resembling autosomal recessive inheritance involving a microdeletion in thrombocytopenia-absent radius syndrome. Am J Hum Genet 2007; 80:232-40. [PMID: 17236129 PMCID: PMC1785342 DOI: 10.1086/510919] [Citation(s) in RCA: 213] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2006] [Accepted: 11/14/2006] [Indexed: 11/03/2022] Open
Abstract
Thrombocytopenia-absent radius (TAR) syndrome is characterized by hypomegakaryocytic thrombocytopenia and bilateral radial aplasia in the presence of both thumbs. Other frequent associations are congenital heart disease and a high incidence of cow's milk intolerance. Evidence for autosomal recessive inheritance comes from families with several affected individuals born to unaffected parents, but several other observations argue for a more complex pattern of inheritance. In this study, we describe a common interstitial microdeletion of 200 kb on chromosome 1q21.1 in all 30 investigated patients with TAR syndrome, detected by microarray-based comparative genomic hybridization. Analysis of the parents revealed that this deletion occurred de novo in 25% of affected individuals. Intriguingly, inheritance of the deletion along the maternal line as well as the paternal line was observed. The absence of this deletion in a cohort of control individuals argues for a specific role played by the microdeletion in the pathogenesis of TAR syndrome. We hypothesize that TAR syndrome is associated with a deletion on chromosome 1q21.1 but that the phenotype develops only in the presence of an additional as-yet-unknown modifier (mTAR).
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Affiliation(s)
- Eva Klopocki
- Institut für Medizinische Genetik, Charité Universitätsmedizin Berlin, Berlin, Germany
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Geddis AE. Inherited Thrombocytopenia: Congenital Amegakaryocytic Thrombocytopenia and Thrombocytopenia With Absent Radii. Semin Hematol 2006; 43:196-203. [PMID: 16822462 DOI: 10.1053/j.seminhematol.2006.04.003] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Thrombocytopenia in the newborn period can signify an inherited platelet disorder. Congenital amegakaryocytic thrombocytopenia (CAMT) and thrombocytopenia with absent radii (TAR) share features of isolated thrombocytopenia, reduced or absent marrow megakaryocytes, impaired responsiveness to thrombopoietin (TPO), and high plasma TPO levels. These disorders are most readily distinguished from each other by the finding of radial aplasia in TAR and the presence of c-MPL mutations in CAMT. In addition, their long-term outcomes are strikingly different: the development of trilineage marrow failure in CAMT in contrast to the general improvement of thrombocytopenia in TAR. The differential diagnosis for CAMT and TAR also includes other congenital disorders in which thrombocytopenia and radial abnormalities can be seen. In this article we will review our molecular and clinical understanding of these two inherited disorders of amegakaryocytosis.
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Affiliation(s)
- Amy E Geddis
- Department of Pediatrics, Division of Pediatric Hematology-Oncology, University of California San Diego, La Jolla, CA, USA.
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Geddis AE. The molecular basis of congenital thrombocytopenias: insights into megakaryopoiesis. ACTA ACUST UNITED AC 2005; 10 Suppl 1:299-305. [PMID: 16188691 DOI: 10.1080/10245330512331390401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- Amy E Geddis
- Department of Pediatrics, University of California, San Diego, USA
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Abstract
Qualitative disorders of platelet function and production form a large group of rare diseases which cover a multitude of genetic defects that by and large have as a common symptom, excessive mucocutaneous bleeding. Glanzmann thrombasthenia, is enabling us to learn much about the pathophysiology of integrins and of how alphaIIb beta3 functions. Bernard-Soulier syndrome, an example of macrothrombocytopenia, combines the production of large platelets with a deficit or non-functioning of the major adhesion receptor of platelets, the GPIb-IX-V complex. Amino acid substitutions in GPIb alpha, may lead to up-regulation and spontaneous binding of von Willebrand factor as in Platelet-type von Willebrand disease. In disorders with defects in the MYH9 gene, macrothrombocytopenias are linked to modifications in kidney, eye or ear, whereas other inherited thrombocytopenias variously link a low platelet count with a propensity to leukemia, skeletal defects, learning impairment, and abnormal red cells. Defects of secretion from platelets include an abnormal alpha-granule formation as in the gray platelet syndrome (with marrow myelofibrosis), and of organelle biogenesis in the Hermansky-Pudlak and Chediak-Higashi syndromes where platelet dense body defects are linked to abnormalities of other lysosomal-like organelles including melanosomes. Finally, defects involving surface receptors (P2Y(12), TPalpha) for activating stimuli, of proteins essential for signaling pathways (including Wiskott-Aldrich syndrome), and of platelet-derived procoagulant activity (Scott syndrome) show how studies on platelet disorders are helping unravel the pathways of primary hemostasis.
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Affiliation(s)
- A T Nurden
- Institut Fédératif de Recherche N 4, CHU Bordeaux, Pessac, France.
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Geddis AE, Kaushansky K. Inherited thrombocytopenias: toward a molecular understanding of disorders of platelet production. Curr Opin Pediatr 2004; 16:15-22. [PMID: 14758109 DOI: 10.1097/00008480-200402000-00005] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE OF REVIEW To review the defined syndromes of inherited thrombocytopenia and discuss new genetic data for several disorders that shed light on the process of megakaryopoiesis. RECENT FINDINGS The genes responsible for several inherited thrombocytopenias have been recently discovered, including congenital amegakaryocytic leukemia, amegakaryocytic thrombocytopenia with radio-ulnar synostosis, familial platelet syndrome with predisposition to acute myelogenous leukemia, Paris-Trousseau, Wiskott-Aldrich syndrome, and the May-Hegglin, Sebastian, Epstein, and Fechner syndromes. These clinical syndromes, combined with studies in mouse and in vitro models, reveal the importance of these genes for normal hematopoiesis. SUMMARY Although inherited syndromes of thrombocytopenia are rare, characterization of mutations in these disorders has contributed greatly to our understanding of megakaryocyte and platelet development. A systematic registry of congenitally thrombocytopenic individuals would almost certainly lead to new genetic discoveries.
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Affiliation(s)
- Amy E Geddis
- Department of Pediatrics, University of California, San Diego, USA.
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Abstract
AbstractCongenital thrombocytopenias, once considered rare and obscure conditions, are today recognized with increasing frequency, especially due to the measurement of platelet number as part of routine blood testing. The clinical spectrum of congenital thrombocytopenia ranges from severe bleeding diatheses, recognized within the first few weeks of life, to mild conditions that may remain undetected even in adulthood. For the latter group of diseases, distinguishing between inherited (primary) and acquired (secondary) thrombocytopenia, especially immune thrombocytopenia purpura (ITP), is essential to avoid unnecessary and potentially harmful treatments. In this review, the congenital thrombocytopenia syndromes are discussed with specific attention focused on diagnostic criteria, clinical presentations, genetic etiology, and current medical management. The mutated genes responsible for each syndrome are reviewed as well as the potential implications for using gene therapy or gene repair in the future.
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Affiliation(s)
- A K Rao
- Department of Medicine, and the Sol Sherry Thrombosis Research Center, Temple University School of Medicine, Philadelphia 19140, USA.
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