1
|
Glembotsky AC, De Luca G, Heller PG. A Deep Dive into the Pathology of Gray Platelet Syndrome: New Insights on Immune Dysregulation. J Blood Med 2021; 12:719-732. [PMID: 34408521 PMCID: PMC8364843 DOI: 10.2147/jbm.s270018] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Accepted: 06/16/2021] [Indexed: 12/22/2022] Open
Abstract
The gray platelet syndrome (GPS) is a rare platelet disorder, characterized by impaired alpha-granule biogenesis in megakaryocytes and platelets due to NBEAL2 mutations. Typical clinical features include macrothrombocytopenia, bleeding and elevated vitamin B12 levels, while bone marrow fibrosis and splenomegaly may develop during disease progression. Recently, the involvement of other blood lineages has been highlighted, revealing the role of NBEAL2 outside the megakaryocyte-platelet axis. Low leukocyte counts, decreased neutrophil granulation and impaired neutrophil extracellular trap formation represent prominent findings in GPS patients, reflecting deranged innate immunity and associated with an increased susceptibility to infection. In addition, low numbers and impaired degranulation of NK cells have been demonstrated in animal models. Autoimmune diseases involving different organs and a spectrum of autoantibodies are present in a substantial proportion of GPS patients, expanding the syndromic spectrum of this disorder and pointing to dysregulation of the adaptive immune response. Low-grade inflammation, as evidenced by elevation of liver-derived acute-phase reactants, is another previously unrecognized feature of GPS which may contribute to disease manifestations. This review will focus on the mechanisms underlying the pathogenesis of blood cell abnormalities in human GPS patients and NBEAL2-null animal models, providing insight into the effects of NBEAL2 in hemostasis, inflammation and immunity.
Collapse
Affiliation(s)
- Ana C Glembotsky
- Departamento Hematología Investigación, Instituto de Investigaciones Médicas "Dr. A. Lanari", Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina.,Departamento Hematología Investigación, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad de Buenos Aires, Instituto de Investigaciones Médicas (IDIM), Buenos Aires, Argentina
| | - Geraldine De Luca
- Departamento Hematología Investigación, Instituto de Investigaciones Médicas "Dr. A. Lanari", Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina.,Departamento Hematología Investigación, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad de Buenos Aires, Instituto de Investigaciones Médicas (IDIM), Buenos Aires, Argentina
| | - Paula G Heller
- Departamento Hematología Investigación, Instituto de Investigaciones Médicas "Dr. A. Lanari", Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina.,Departamento Hematología Investigación, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad de Buenos Aires, Instituto de Investigaciones Médicas (IDIM), Buenos Aires, Argentina
| |
Collapse
|
2
|
Tariq H, Perez Botero J, Higgins RA, Medina EA. Gray Platelet Syndrome Presenting With Pancytopenia, Splenomegaly, and Bone Marrow Fibrosis. Am J Clin Pathol 2021; 156:253-258. [PMID: 33586768 DOI: 10.1093/ajcp/aqaa229] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
OBJECTIVES Gray platelet syndrome (GPS) is a rare platelet storage pool disorder associated with a marked decrease or absence of platelet α-granules and their contents. It is characterized clinically by mild to moderate bleeding; moderate macrothrombocytopenia with large, agranular platelets; splenomegaly; and bone marrow fibrosis. Electron microscopy confirms markedly reduced or absent α-granules in platelets and megakaryocytes. The classic description of GPS is caused by homozygous mutations in NBEAL2 (neurobeachinlike 2). METHODS A 28-year-old Hispanic man with a history of easy bruising and occasional episodes of epistaxis sought treatment for pancytopenia and splenomegaly. Peripheral blood smear and bone marrow analysis, electron microscopy, and next-generation sequencing were performed. RESULTS Large and agranular platelets were present in the peripheral blood. There was bone marrow fibrosis. Electron microscopy of the platelets showed absence of α-granules. Next-generation sequencing revealed a germline apparently homozygous nonsense variant in the NBEAL2 gene: c.5674C>T, p.Gln1892X (p.Q1829X). CONCLUSIONS The differential diagnosis of GPS includes a myeloid neoplasm such as myelodysplastic syndrome with bone marrow fibrosis. The availability of diagnostic genetic panels for hereditable platelet disorders can assist in the recognition of GPS and other platelet disorders. We also describe a previously unreported pathogenic germline homozygous nonsense variant in the NBEAL2 gene: c.5674C>T, p.Gln1892X (p.Q1829X) in a patient with GPS.
Collapse
Affiliation(s)
- Hamza Tariq
- Department of Pathology and Laboratory Medicine, University of Texas Health Science Center, San Antonio, TX, USA
| | | | - Russell A Higgins
- Department of Pathology and Laboratory Medicine, University of Texas Health Science Center, San Antonio, TX, USA
| | - Edward A Medina
- Department of Pathology and Laboratory Medicine, University of Texas Health Science Center, San Antonio, TX, USA
| |
Collapse
|
3
|
Abstract
Storage pool deficiency (SPD) is a group of rare platelet disorders that result from deficiencies in α-granules, δ-granules, or both. One type of α-SPD is gray platelet syndrome (GPS), caused by mutations in the neurobeachin-like 2 (NBEAL2) gene that results in a bleeding diathesis, thrombocytopenia, splenomegaly, and progressive myelofibrosis. Due to the lack of α-granules, platelets have a gray and degranulated appearance by light microscopy. However, definitive diagnosis of GPS requires confirmation of α-granule deficiency by electron microscopy. Treatment is nonspecific, with the conservative utilization of platelet transfusions being the most important form of therapy. We present a case of a 17-year-old female with a past medical history of thrombocytopenia, first identified at the age of five. Her clinical symptomatology included chronic fatigue, gingival bleeding, bruising, menorrhagia, and leg pain. This report will discuss both the clinical and the pathophysiologic aspects of this rare platelet disorder.
Collapse
Affiliation(s)
- Roger Riley
- Departments of Pathology, Virginia Commonwealth University (VCU) School of Medicine, Richmond
| | - Asad Khan
- Departments of Pediatrics, Virginia Commonwealth University (VCU) School of Medicine, Richmond
| | - Shella Pai
- Departments of Pathology, Virginia Commonwealth University (VCU) School of Medicine, Richmond
| | - Laura Warmke
- Department of Pathology and Laboratory Medicine, University of Texas MD Anderson Cancer Center, Houston
| | | | - William Gunning
- Department of Pathology, University of Toledo College of Medicine, Toledo, Ohio
| |
Collapse
|
4
|
Abstract
Homozygosity/compound heterozygosity for loss of function mutations in neurobeachin-like 2 (NBEAL2) is causative for Gray platelet syndrome (GPS; MIM #139090), characterized by thrombocytopenia and large platelets lacking α-granules and cargo. Most GPS-associated NBEAL2 mutations generate nonsense codons; frameshifts causing premature translation termination and/or changes in mRNA splicing have also been observed. Data regarding NBEAL2 protein expression in GPS patients is limited. We observed absence of NBEAL2 in platelets from GPS patients with 3 different genotypes, and reduced/truncated platelet NBEAL2 has been reported for others. GPS is commonly associated with mild bleeding, but lifethreatening bleeding has been reported in some cases. A common long-term complication in GPS patients is myelofibrosis; splenomegaly is less common but sometimes of sufficient severity to merit splenectomy. Like GPS patients, mice lacking NBEAL2 expression exhibit macrothrombocytopenia, deficiency of platelet α-granules, splenomegaly, myelofibrosis, impaired platelet function and abnormalities in megakaryocyte development. Animal studies have also reported impaired platelet function in vivo using laser injury and thrombo-inflammation models. NBEAL2 is a large gene with 54 exons, and several putative functional domains have been identified in NBEAL2, including PH (pleckstrin homology) and BEACH (beige and Chediak-Higashi) domains shared with other members of a protein family that includes LYST and LRBA, also expressed by hematopoietic cells. Potential NBEAL2-interacting proteins have recently been identified, and it is expected that current and future efforts will reveal the cellular mechanisms by which NBEAL2 facilitates platelet development and supports hemostatic function.
Collapse
Affiliation(s)
- Fred G Pluthero
- a Cell Biology Program , Research Institute, Hospital for Sick Children , Toronto , ON , Canada
| | - Jorge Di Paola
- b Department of Pediatrics and Human Genetics and Genomics Program , University of Colorado, Anschutz Medical Campus , Aurora , CO , USA
| | - Manuel D Carcao
- c Division of Haematology/Oncology, Department of Paediatrics , University of Toronto and The Hospital for Sick Children , Toronto , ON , Canada.,d Child Health Evaluative Sciences , Research Institute, Hospital for Sick Children , Toronto , ON , Canada
| | - Walter H A Kahr
- a Cell Biology Program , Research Institute, Hospital for Sick Children , Toronto , ON , Canada.,c Division of Haematology/Oncology, Department of Paediatrics , University of Toronto and The Hospital for Sick Children , Toronto , ON , Canada.,e Department of Biochemistry , University of Toronto , Toronto , ON , Canada
| |
Collapse
|
5
|
Mayer L, Jasztal M, Pardo M, Aguera de Haro S, Collins J, Bariana TK, Smethurst PA, Grassi L, Petersen R, Nurden P, Favier R, Yu L, Meacham S, Astle WJ, Choudhary J, Yue WW, Ouwehand WH, Guerrero JA. Nbeal2 interacts with Dock7, Sec16a, and Vac14. Blood 2018; 131:1000-11. [PMID: 29187380 DOI: 10.1182/blood-2017-08-800359] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Accepted: 11/21/2017] [Indexed: 12/11/2022] Open
Abstract
Mutations in NBEAL2, the gene encoding the scaffolding protein Nbeal2, are causal of gray platelet syndrome (GPS), a rare recessive bleeding disorder characterized by platelets lacking α-granules and progressive marrow fibrosis. We present here the interactome of Nbeal2 with additional validation by reverse immunoprecipitation of Dock7, Sec16a, and Vac14 as interactors of Nbeal2. We show that GPS-causing mutations in its BEACH domain have profound and possible effects on the interaction with Dock7 and Vac14, respectively. Proximity ligation assays show that these 2 proteins are physically proximal to Nbeal2 in human megakaryocytes. In addition, we demonstrate that Nbeal2 is primarily localized in the cytoplasm and Dock7 on the membrane of or in α-granules. Interestingly, platelets from GPS cases and Nbeal2-/- mice are almost devoid of Dock7, resulting in a profound dysregulation of its signaling pathway, leading to defective actin polymerization, platelet activation, and shape change. This study shows for the first time proteins interacting with Nbeal2 and points to the dysregulation of the canonical signaling pathway of Dock7 as a possible cause of the aberrant formation of platelets in GPS cases and Nbeal2-deficient mice.
Collapse
|
6
|
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] [What about the content of this article? (0)] [Affiliation(s)] [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.
Collapse
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
| | | |
Collapse
|