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Nagoshi R, Sakamoto A, Imai T, Uchiyama T, Kaname T, Kunishima S, Ishiguro A. Bernard-Soulier syndrome caused by a novel GP1BB variant and 22q11.2 deletion. Int J Hematol 2024:10.1007/s12185-024-03768-2. [PMID: 38625506 DOI: 10.1007/s12185-024-03768-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2024] [Revised: 03/25/2024] [Accepted: 03/28/2024] [Indexed: 04/17/2024]
Abstract
Bernard-Soulier syndrome (BSS) is caused by defects in GP1BA, GP1BB, or GP9 genes. Patients with 22q11.2 deletion syndrome (22q11.2DS) are obligate carriers of BSS because GP1BB resides on chromosome 22q11.2. A 15-month-old girl without bleeding symptoms had giant platelets and thrombocytopenia. Physical findings and macrothrombocytopenia suggested 22q11.2DS, which was confirmed by fluorescence in situ hybridization. Flow cytometry showed decreased GPIbα on the platelets. Gene panel testing revealed a novel variant in GP1BB, p.(Val169_Leu172del). These findings confirmed that the patient had BSS. This case suggests that any patient with 22q11.2DS and macrothrombocytopenia should be further tested for BSS.
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Affiliation(s)
- Rintaro Nagoshi
- Center for Postgraduate Education and Training, National Center for Child Health and Development (NCCHD), Tokyo, Japan
| | - Atsushi Sakamoto
- Division of Hematology, Center for Postgraduate Education and Training, NCCHD, 2-10-1 Okura, Setagaya-Ku, Tokyo, 157-8535, Japan.
| | - Tsuyoshi Imai
- Department of Pediatric Hematology and Oncology, National Hospital Organization Shikoku Medical Center for Children and Adults, Kagawa, Japan
| | | | | | - Shinji Kunishima
- Department of Medical Technology, School of Health Sciences, Gifu University of Medical Science, Gifu, Japan
| | - Akira Ishiguro
- Center for Postgraduate Education and Training, National Center for Child Health and Development (NCCHD), Tokyo, Japan
- Division of Hematology, Center for Postgraduate Education and Training, NCCHD, 2-10-1 Okura, Setagaya-Ku, Tokyo, 157-8535, Japan
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2
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Martinez-Navajas G, Ceron-Hernandez J, Simon I, Lupiañez P, Diaz-McLynn S, Perales S, Modlich U, Guerrero JA, Martin F, Sevivas T, Lozano ML, Rivera J, Ramos-Mejia V, Tersteeg C, Real PJ. Lentiviral gene therapy reverts GPIX expression and phenotype in Bernard-Soulier syndrome type C. MOLECULAR THERAPY. NUCLEIC ACIDS 2023; 33:75-92. [PMID: 37416759 PMCID: PMC10320622 DOI: 10.1016/j.omtn.2023.06.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Accepted: 06/08/2023] [Indexed: 07/08/2023]
Abstract
Bernard-Soulier syndrome (BSS) is a rare congenital disease characterized by macrothrombocytopenia and frequent bleeding. It is caused by pathogenic variants in three genes (GP1BA, GP1BB, or GP9) that encode for the GPIbα, GPIbβ, and GPIX subunits of the GPIb-V-IX complex, the main platelet surface receptor for von Willebrand factor, being essential for platelet adhesion and aggregation. According to the affected gene, we distinguish BSS type A1 (GP1BA), type B (GP1BB), or type C (GP9). Pathogenic variants in these genes cause absent, incomplete, or dysfunctional GPIb-V-IX receptor and, consequently, a hemorrhagic phenotype. Using gene-editing tools, we generated knockout (KO) human cellular models that helped us to better understand GPIb-V-IX complex assembly. Furthermore, we developed novel lentiviral vectors capable of correcting GPIX expression, localization, and functionality in human GP9-KO megakaryoblastic cell lines. Generated GP9-KO induced pluripotent stem cells produced platelets that recapitulated the BSS phenotype: absence of GPIX on the membrane surface and large size. Importantly, gene therapy tools reverted both characteristics. Finally, hematopoietic stem cells from two unrelated BSS type C patients were transduced with the gene therapy vectors and differentiated to produce GPIX-expressing megakaryocytes and platelets with a reduced size. These results demonstrate the potential of lentiviral-based gene therapy to rescue BSS type C.
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Affiliation(s)
- Gonzalo Martinez-Navajas
- GENyO, Pfizer-Universidad de Granada-Junta de Andalucia Centre for Genomics and Oncological Research, PTS, Granada, Avenida de la Ilustracion 114, 18016 Granada, Spain
- University of Granada, Department of Biochemistry and Molecular Biology I, Faculty of Science, Avenida Fuentenueva S/n, 18071 Granada, Spain
| | - Jorge Ceron-Hernandez
- GENyO, Pfizer-Universidad de Granada-Junta de Andalucia Centre for Genomics and Oncological Research, PTS, Granada, Avenida de la Ilustracion 114, 18016 Granada, Spain
- University of Granada, Department of Biochemistry and Molecular Biology I, Faculty of Science, Avenida Fuentenueva S/n, 18071 Granada, Spain
| | - Iris Simon
- GENyO, Pfizer-Universidad de Granada-Junta de Andalucia Centre for Genomics and Oncological Research, PTS, Granada, Avenida de la Ilustracion 114, 18016 Granada, Spain
- University of Granada, Department of Biochemistry and Molecular Biology I, Faculty of Science, Avenida Fuentenueva S/n, 18071 Granada, Spain
| | - Pablo Lupiañez
- GENyO, Pfizer-Universidad de Granada-Junta de Andalucia Centre for Genomics and Oncological Research, PTS, Granada, Avenida de la Ilustracion 114, 18016 Granada, Spain
- University of Granada, Department of Biochemistry and Molecular Biology I, Faculty of Science, Avenida Fuentenueva S/n, 18071 Granada, Spain
| | - Sofia Diaz-McLynn
- GENyO, Pfizer-Universidad de Granada-Junta de Andalucia Centre for Genomics and Oncological Research, PTS, Granada, Avenida de la Ilustracion 114, 18016 Granada, Spain
| | - Sonia Perales
- GENyO, Pfizer-Universidad de Granada-Junta de Andalucia Centre for Genomics and Oncological Research, PTS, Granada, Avenida de la Ilustracion 114, 18016 Granada, Spain
- University of Granada, Department of Biochemistry and Molecular Biology I, Faculty of Science, Avenida Fuentenueva S/n, 18071 Granada, Spain
- Instituto de Investigación Biosanitaria Ibs.GRANADA, Granada, Spain
| | - Ute Modlich
- Department of Gene and Cell Therapy, Institute of Regenerative Medicine, University of Zürich, Wagistrasse 12, 8952 Schlieren-Zürich, Switzerland
| | - Jose A. Guerrero
- Department of Haematology, University of Cambridge, Cambridge, UK
- National Health Service Blood and Transplant, Cambridge Biomedical Campus, Cambridge, UK
| | - Francisco Martin
- GENyO, Pfizer-Universidad de Granada-Junta de Andalucia Centre for Genomics and Oncological Research, PTS, Granada, Avenida de la Ilustracion 114, 18016 Granada, Spain
- University of Granada, Department of Biochemistry and Molecular Biology III and Immunology, Faculty of Medicine, Avenida Ilustracion S/n, 18016 Granada, Spain
| | - Teresa Sevivas
- Serviço de Sangue, Medicina Transfusional e Imunohemoterapia Do Centro Hospitalar e Universitário de Coimbra, Coimbra, Portugal
| | - Maria L. Lozano
- Servicio de Hematología y Oncología Médica, Hospital Universitario Morales Meseguer, Centro Regional de Hemodonación, Universidad de Murcia, IMIB-Pascual Parrilla, CIBERER-ISCIII, U765 Murcia, Spain
| | - Jose Rivera
- Servicio de Hematología y Oncología Médica, Hospital Universitario Morales Meseguer, Centro Regional de Hemodonación, Universidad de Murcia, IMIB-Pascual Parrilla, CIBERER-ISCIII, U765 Murcia, Spain
- Grupo Español de Alteraciones Plaquetarias Congénitas (GEAPC), Madrid, Spain
| | - Veronica Ramos-Mejia
- GENyO, Pfizer-Universidad de Granada-Junta de Andalucia Centre for Genomics and Oncological Research, PTS, Granada, Avenida de la Ilustracion 114, 18016 Granada, Spain
| | - Claudia Tersteeg
- Laboratory for Thrombosis Research, IRF Life Sciences, KU Leuven Campus Kulak Kortrijk, Kortrijk, Belgium
| | - Pedro J. Real
- GENyO, Pfizer-Universidad de Granada-Junta de Andalucia Centre for Genomics and Oncological Research, PTS, Granada, Avenida de la Ilustracion 114, 18016 Granada, Spain
- University of Granada, Department of Biochemistry and Molecular Biology I, Faculty of Science, Avenida Fuentenueva S/n, 18071 Granada, Spain
- Instituto de Investigación Biosanitaria Ibs.GRANADA, Granada, Spain
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Morrow BE, McDonald-McGinn DM, Emanuel BS, Vermeesch JR, Scambler PJ. Molecular genetics of 22q11.2 deletion syndrome. Am J Med Genet A 2019; 176:2070-2081. [PMID: 30380194 DOI: 10.1002/ajmg.a.40504] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Revised: 06/11/2018] [Accepted: 07/17/2018] [Indexed: 02/02/2023]
Abstract
The 22q11.2 deletion syndrome (22q11.2DS) is a congenital malformation and neuropsychiatric disorder caused by meiotic chromosome rearrangements. One of the goals of this review is to summarize the current state of basic research studies of 22q11.2DS. It highlights efforts to understand the mechanisms responsible for the 22q11.2 deletion that occurs in meiosis. This mechanism involves the four sets of low copy repeats (LCR22) that are dispersed in the 22q11.2 region and the deletion is mediated by nonallelic homologous recombination events. This review also highlights selected genes mapping to the 22q11.2 region that may contribute to the typical clinical findings associated with the disorder and explain that mutations in genes on the remaining allele can uncover rare recessive conditions. Another important aspect of 22q11.2DS is the existence of phenotypic heterogeneity. While some patients are mildly affected, others have severe medical, cognitive, and/or psychiatric challenges. Variability may be due in part to the presence of genetic modifiers. This review discusses current genome-wide efforts to identify such modifiers that could shed light on molecular pathways required for normal human development, cognition or behavior.
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Affiliation(s)
- Bernice E Morrow
- Department of Genetics, Albert Einstein College of Medicine, Bronx, New York
| | - Donna M McDonald-McGinn
- Division of Human Genetics, Children's Hospital of Philadelphia and Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia
| | - Beverly S Emanuel
- Division of Human Genetics, Children's Hospital of Philadelphia and Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia
| | - Joris R Vermeesch
- Center for Human Genetics, Katholieke Universiteit Leuven (KU Leuven), Leuven, Belgium
| | - Peter J Scambler
- Institute of Child Health, University College London, London, UK
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Zwifelhofer NMJ, Bercovitz RS, Weik LA, Moroi A, LaRose S, Newman PJ, Newman DK. Hemizygosity for the gene encoding glycoprotein Ibβ is not responsible for macrothrombocytopenia and bleeding in patients with 22q11 deletion syndrome. J Thromb Haemost 2019; 17:295-305. [PMID: 30549403 PMCID: PMC6410711 DOI: 10.1111/jth.14357] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Indexed: 12/17/2022]
Abstract
Essentials How thrombocytopenia relates to bleeding in 22q11 deletion syndrome (22q11DS) is not clear. Bleeding severity, platelet count and volume, and GPIBB were examined in patients with 22q11DS. Macrothrombocytopenia and bleeding typified imperfectly overlapping subsets of 22q11DS patients. GPIBB hemizygosity does not cause macrothrombocytopenia or bleeding in patients with 22q11DS. SUMMARY: Background and objectives Macrothrombocytopenia and bleeding are frequently associated with 22q11 deletion syndrome (22q11DS). GPIBB, which encodes the glycoprotein (GP) Ibβ subunit of GPIb-IX-V, is commonly deleted in patients with 22q11DS. Absence of functional GPIb-IX-V causes Bernard-Soulier syndrome, which is a severe bleeding disorder characterized by macrothrombocytopenia. Patients with 22q11DS are often obligate hemizygotes for GPIBB, and those with only a pathogenically disrupted copy of GPIBB present with Bernard-Soulier syndrome. The objective of this study was to determine how GPIBB hemizygosity and sequence variation relate to macrothrombocytopenia and bleeding in patients with 22q11DS who do not have Bernard-Soulier syndrome. Patients/methods We thoroughly characterized bleeding severity, mean platelet volume, platelet count and GPIBB copy number and sequence in patients with 22q11DS. Results and conclusions Macrothrombocytopenia and mild bleeding were observed in incompletely overlapping subsets of patients, and GPIBB copy number and sequence variation did not correlate with either macrothrombocytopenia or bleeding in patients with 22q11DS. These findings indicate that GPIBB hemizygosity does not result in either macrothrombocytopenia or bleeding in these patients. Alternative genetic causes of macrothrombocytopenia, potential causes of acquired thrombocytopenia and bleeding and ways in which platelet size, platelet count and GPIBB sequence information can be used to aid in the diagnosis and management of patients with 22q11DS are discussed.
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Affiliation(s)
- N M J Zwifelhofer
- Blood Research Institute, BloodCenter of Wisconsin - part of Versiti, Milwaukee, WI, USA
| | - R S Bercovitz
- Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, IL, USA
- Department of Pediatrics, Division of Hematology and Oncology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - L A Weik
- Children's Hospital of Wisconsin, Milwaukee, WI, USA
| | - A Moroi
- Blood Research Institute, BloodCenter of Wisconsin - part of Versiti, Milwaukee, WI, USA
| | - S LaRose
- Blood Research Institute, BloodCenter of Wisconsin - part of Versiti, Milwaukee, WI, USA
| | - P J Newman
- Blood Research Institute, BloodCenter of Wisconsin - part of Versiti, Milwaukee, WI, USA
- Department of Cell Biology, Neurobiology & Anatomy, Medical College of Wisconsin, Milwaukee, WI, USA
| | - D K Newman
- Blood Research Institute, BloodCenter of Wisconsin - part of Versiti, Milwaukee, WI, USA
- Department of Pharmacology & Toxicology, Medical College of Wisconsin, Milwaukee, WI, USA
- Department of Microbiology & Immunology, Medical College of Wisconsin, Milwaukee, WI, USA
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Eguchi M, Ozaki E, Yamauchi T, Ohta M, Higaki T, Masuda K, Imoto I, Ishii E, Eguchi-Ishimae M. Manifestation of recessive combined D-2-, L-2-hydroxyglutaric aciduria in combination with 22q11.2 deletion syndrome. Am J Med Genet A 2017; 176:351-358. [PMID: 29265763 DOI: 10.1002/ajmg.a.38578] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2017] [Revised: 10/13/2017] [Accepted: 11/16/2017] [Indexed: 11/09/2022]
Abstract
22q11.2 deletion syndrome is one of the most common human microdeletion syndromes. The clinical phenotype of 22q11.2 deletion syndrome is variable, ranging from mild to life-threatening symptoms, depending mainly on the extent of the deleted region. Brain malformations described in association with 22q11.2 deletion syndrome include polymicrogyria, cerebellar hypoplasia, megacisterna magna, and agenesis of the corpus callosum (ACC), although these are rare. We report here for the first time a patient who manifested combined D-2- and L-2-hydroxyglutaric aciduria as a result of a hemizygous mutation in SLC25A1 in combination with 22q11.2 deletion. The girl was diagnosed to have ACC shortly after birth and a deletion of 22q11.2 was identified by genetic analysis. Although the patient showed cardiac anomalies, which is one of the typical symptoms of 22q11.2 deletion syndrome, her rather severe phenotype and atypical face prompted us to search for additional pathogenic mutations. Three genes present in the deleted 22q11.2 region, SLC25A1, TUBA8, and SNAP29, which have been reported to be associated with brain malformation, were analyzed for the presence of pathogenic mutations. A frameshift mutation, c.18_24dup (p.Ala9Profs*82), was identified in the first exon of the remaining SLC25A1 allele, resulting in the complete loss of normal SLC25A1 function in the patient's cells. Our results support the notion that the existence of another genetic abnormality involving the retained allele on 22q11.2 should be considered when atypical or rare phenotypes are observed.
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Affiliation(s)
- Mariko Eguchi
- Department of Pediatrics, Ehime University Graduate School of Medicine, Toon, Ehime, Japan.,Division of Medical Genetics, Ehime University Hospital, Toon, Ehime, Japan
| | - Erina Ozaki
- Division of Medical Genetics, Ehime University Hospital, Toon, Ehime, Japan.,Department of Total Medical Support Center, Ehime University Hospital, Toon, Ehime, Japan
| | - Toshifumi Yamauchi
- Department of Neonatology, Maternity & Perinatal Care Unit, Ehime University Hospital, Toon, Ehime, Japan
| | - Masaaki Ohta
- Department of Neonatology, Maternity & Perinatal Care Unit, Ehime University Hospital, Toon, Ehime, Japan
| | - Takashi Higaki
- Department of Regional Pediatrics and Perinatology, Ehime University Graduate School of Medicine, Toon, Ehime, Japan
| | - Kiyoshi Masuda
- Department of Human Genetics, Graduate School of Biomedical Sciences, Tokushima University, Tokushima, Japan
| | - Issei Imoto
- Department of Human Genetics, Graduate School of Biomedical Sciences, Tokushima University, Tokushima, Japan
| | - Eiichi Ishii
- Department of Pediatrics, Ehime University Graduate School of Medicine, Toon, Ehime, Japan.,Division of Medical Genetics, Ehime University Hospital, Toon, Ehime, Japan
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Lambert MP, Arulselvan A, Schott A, Markham SJ, Crowley TB, Zackai EH, McDonald-McGinn DM. The 22q11.2 deletion syndrome: Cancer predisposition, platelet abnormalities and cytopenias. Am J Med Genet A 2017; 176:2121-2127. [PMID: 28940864 DOI: 10.1002/ajmg.a.38474] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2017] [Revised: 08/08/2017] [Accepted: 08/21/2017] [Indexed: 01/10/2023]
Abstract
The 22q11.2 deletion syndrome (DS) is associated with variable phenotypic expression as findings range from severely affected individuals with the classical triad of DiGeorge and velocardiofacial syndromes, including congenital heart disease, immunodeficiency, hypocalcemia, and palatal abnormalities, to subtly affected adults who only come to attention following the diagnosis of a more severely affected child. The multiple manifestations can affect all organ systems, including the hematologic system resulting in baseline lower platelet counts for individuals with 22q11.2DS and increased platelet size. In addition, there may be an associated increased risk of bleeding. Individuals with 22q11.2DS are also at increased risk of autoimmune cytopenias that can complicate the evaluation or management of other manifestations. Finally, there may be an increased risk of malignancy, although the mechanism for this risk is not fully understood. This review summarizes the currently available data on hematologic/oncologic manifestations of 22q11.2DS and reports on our findings within a large cohort of individuals with the deletion.
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Affiliation(s)
- Michele P Lambert
- Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania.,Department of Pediatrics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
| | - Abinaya Arulselvan
- Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
| | - Amanda Schott
- Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania.,Arcadia University, Glenside, Pennsylvania
| | - Stephen J Markham
- Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
| | - Terrance B Crowley
- Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
| | - Elaine H Zackai
- Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania.,Department of Pediatrics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
| | - Donna M McDonald-McGinn
- Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania.,Department of Pediatrics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
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Savoia A, Kunishima S, De Rocco D, Zieger B, Rand ML, Pujol-Moix N, Caliskan U, Tokgoz H, Pecci A, Noris P, Srivastava A, Ward C, Morel-Kopp MC, Alessi MC, Bellucci S, Beurrier P, de Maistre E, Favier R, Hézard N, Hurtaud-Roux MF, Latger-Cannard V, Lavenu-Bombled C, Proulle V, Meunier S, Négrier C, Nurden A, Randrianaivo H, Fabris F, Platokouki H, Rosenberg N, HadjKacem B, Heller PG, Karimi M, Balduini CL, Pastore A, Lanza F. Spectrum of the mutations in Bernard-Soulier syndrome. Hum Mutat 2014; 35:1033-45. [PMID: 24934643 DOI: 10.1002/humu.22607] [Citation(s) in RCA: 101] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2014] [Accepted: 06/06/2014] [Indexed: 01/05/2023]
Abstract
Bernard-Soulier syndrome (BSS) is a rare autosomal recessive bleeding disorder characterized by defects of the GPIb-IX-V complex, a platelet receptor for von Willebrand factor (VWF). Most of the mutations identified in the genes encoding for the GP1BA (GPIbα), GP1BB (GPIbβ), and GP9 (GPIX) subunits prevent expression of the complex at the platelet membrane or more rarely its interaction with VWF. As a consequence, platelets are unable to adhere to the vascular subendothelium and agglutinate in response to ristocetin. In order to collect information on BSS patients, we established an International Consortium for the study of BSS, allowing us to enrol and genotype 132 families (56 previously unreported). With 79 additional families for which molecular data were gleaned from the literature, the 211 families characterized so far have mutations in the GP1BA (28%), GP1BB (28%), or GP9 (44%) genes. There is a wide spectrum of mutations with 112 different variants, including 22 novel alterations. Consistent with the rarity of the disease, 85% of the probands carry homozygous mutations with evidence of founder effects in some geographical areas. This overview provides the first global picture of the molecular basis of BSS and will lead to improve patient diagnosis and management.
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Affiliation(s)
- Anna Savoia
- Institute for Maternal and Child Health - IRCCS "Burlo Garofolo", Trieste, Italy; Department of Medical Sciences, University of Trieste, Trieste, Italy
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8
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Kumar L, Chou J, Yee CSK, Borzutzky A, Vollmann EH, von Andrian UH, Park SY, Hollander G, Manis JP, Poliani PL, Geha RS. Leucine-rich repeat containing 8A (LRRC8A) is essential for T lymphocyte development and function. ACTA ACUST UNITED AC 2014; 211:929-42. [PMID: 24752297 PMCID: PMC4010910 DOI: 10.1084/jem.20131379] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Lrrc8a is a ubiquitously expressed gene that encodes a leucine-rich repeat (LRR)-containing protein detected at higher levels on the surface of thymocytes than on other immune cells. We generated Lrrc8a(-/-) mice to investigate the role of LRRC8A in lymphocyte development and function. Lrrc8a(-/-) mice had increased prenatal and postnatal mortality, growth retardation, and multiple tissue abnormalities. Lrrc8a(-/-) mice displayed a modest block in B cell development but intact intrinsic B cell function. In contrast, both Lrrc8a(-/-) mice and Lrrc8a(-/-)→Rag2(-/-) bone marrow chimeras exhibited a severe cell-intrinsic block in early thymic development, with decreased proliferation and increased apoptosis of thymocytes, and impaired peripheral T cell function. Thymic epithelial cells expressed an LRRC8A ligand that was critical for double-negative to double-positive thymocyte differentiation and survival in vitro. LRRC8A constitutively associated with the GRB2-GAB2 complex and lymphocyte-specific protein tyrosine kinase (LCK) in thymocytes. LRRC8A ligation activated AKT via the LCK-ZAP-70-GAB2-PI3K pathway, and AKT phosphorylation was markedly reduced in the thymus of Lrrc8a(-/-) mice. These findings reveal an essential role for LRRC8A in T cell development, survival, and function.
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Affiliation(s)
- Lalit Kumar
- Division of Immunology and 2 Joint Program in Transfusion Medicine, Division of Laboratory Medicine, Boston Children's Hospital; and 3 Department of Pediatrics, 4 Department of Microbiology and Immunobiology, and 5 Department of Pathology, Harvard Medical School, Boston, MA 02115
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9
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Kunishima S, Imai T, Kobayashi R, Kato M, Ogawa S, Saito H. Bernard-Soulier syndrome caused by a hemizygous GPIbβ mutation and 22q11.2 deletion. Pediatr Int 2013; 55:434-7. [PMID: 23566026 DOI: 10.1111/ped.12105] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2012] [Revised: 12/17/2012] [Accepted: 03/25/2013] [Indexed: 11/30/2022]
Abstract
BACKGROUND Bernard-Soulier syndrome (BSS) is a rare autosomal recessive bleeding disorder characterized by giant platelets, thrombocytopenia, and a prolonged bleeding time, which is caused by homozygous mutations in the GPIbα, GPIbβ, or GPIX genes. The 22q11.2 deletion syndrome (22q11.2DS) is caused by a microdeletion on chromosome 22, which includes the GPIbβ gene, and is characterized by abnormal development of the pharyngeal apparatus and heart. Thus, patients with 22q11.2DS are obligate carriers for BSS. METHODS We evaluated two infants with BSS and performed the genetic analysis of the GPIbα, GPIbβ, or GPIX genes, and investigated the segregation of the mutation within the families. The status of the 22q11.2 deletion was examined by fluorescence in situ hybridization and single-nucleotide polymorphism array copy number analysis. RESULTS DNA sequencing analysis revealed that the infants were compound heterozygous for a hemizygous mutation in the GPIbβ gene (p.Trp148X and p.Leu97Phe, respectively) and 22q11.2 deletion in the other chromosome. Both infants had the common 3Mb 22q11.2 deletion but did not show major phenotypic features of 22q11.2DS, such as developmental delay, cardiac defects, dysmorphic facial features, palatal anomalies, hypocalcemia, and immune deficiency. The 22q11.2DS would not have become clear if detailed molecular genetic analyses of BSS had not been performed. CONCLUSIONS Our cases illustrate that a suspicion of 22q11.2 deletion is warranted in pediatric BSS patients with a mutation in the GPIbβ gene, even without remarkable symptoms.
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Affiliation(s)
- Shinji Kunishima
- Department of Advanced Diagnosis, Clinical Research Center, National Hospital Organization Nagoya Medical Center, Nagoya, Japan.
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10
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Quaternary organization of GPIb-IX complex and insights into Bernard-Soulier syndrome revealed by the structures of GPIbβ and a GPIbβ/GPIX chimera. Blood 2011; 118:5292-301. [PMID: 21908432 DOI: 10.1182/blood-2011-05-356253] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Platelet GPIb-IX receptor complex has 3 subunits GPIbα, GPIbβ, and GPIX, which assemble with a ratio of 1:2:1. Dysfunction in surface expression of the complex leads to Bernard-Soulier syndrome. We have crystallized the GPIbβ ectodomain (GPIbβ(E)) and determined the structure to show a single leucine-rich repeat with N- and C-terminal disulphide-bonded capping regions. The structure of a chimera of GPIbβ(E) and 3 loops (a,b,c) taken from the GPIX ectodomain sequence was also determined. The chimera (GPIbβ(Eabc)), but not GPIbβ(E), forms a tetramer in the crystal, showing a quaternary interface between GPIbβ and GPIX. Central to this interface is residue Tyr106 from GPIbβ, which inserts into a pocket generated by 2 loops (b,c) from GPIX. Mutagenesis studies confirmed this interface as a valid representation of interactions between GPIbβ and GPIX in the full-length complex. Eight GPIbβ missense mutations identified from patients with Bernard-Soulier syndrome were examined for changes to GPIb-IX complex surface expression. Two mutations, A108P and P74R, were found to maintain normal secretion/folding of GPIbβ(E) but were unable to support GPIX surface expression. The close structural proximity of these mutations to Tyr106 and the GPIbβ(E) interface with GPIX indicates they disrupt the quaternary organization of the GPIb-IX complex.
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Heat-shock protein gp96/grp94 is an essential chaperone for the platelet glycoprotein Ib-IX-V complex. Blood 2011; 117:7136-44. [PMID: 21576699 DOI: 10.1182/blood-2011-01-330464] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The platelet glycoprotein Ib-IX-V complex (GPIb-IX-IV) is the receptor for VWF and is responsible for VWF-mediated platelet activation and aggregation. Loss of the GPIb-IX-V complex is pathogenic for Bernard-soulier Syndrome (BSS), which is characterized by macrothrombocytopenia and impaired platelet function. It remains unclear how the GPIb-IX-V complex is assembled and whether there is a role for a specific molecular chaperone in the process. In the present study, we report that the assembly of the GPIb-IX-V complex depends critically on a molecular chaperone in the endoplasmic reticulum (ER): gp96 (also known as grp94 and HSP90b1). gp96/grp94 deletion in the murine hematopoietic system results in thrombocytopenia, prolonged bleeding time, and giant platelets that are clinically indistinguishable from human BSS. Loss of gp96/grp94 in vivo and in vitro leads to the concomitant reduction in GPIb-IX complex expression due to ER-associated degradation. We further demonstrate that gp96/grp94 binds selectively to the GPIX subunit, but not to gpIbα or gpIbβ. Therefore, we identify the platelet GPIX subunit of the GPIb-IX-V complex as an obligate and novel client of gp96/grp94.
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Mo X, Nguyen NX, McEwan PA, Zheng X, López JA, Emsley J, Li R. Binding of platelet glycoprotein Ibbeta through the convex surface of leucine-rich repeats domain of glycoprotein IX. J Thromb Haemost 2009; 7:1533-40. [PMID: 19566547 PMCID: PMC3046765 DOI: 10.1111/j.1538-7836.2009.03536.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
BACKGROUND The mechanism of assembly of the platelet glycoprotein (GP) Ib-IX complex from GPIbalpha, GPIbbeta and GPIX subunits is not entirely clear. In this complex, ectodomains of both GPIbbeta and GPIX subunits contain two leucine-rich repeats (LRR) and share high sequence similarity. However, they differ noticeably in stability, hampering further analysis of their interaction. OBJECTIVES AND METHODS Guided by analysis of the LRR structure, we report a well-folded Ibbeta/IX chimera and its usage in dissecting GPIX function. RESULTS In this chimera, three non-contiguous sequences that may constitute the putative convex surface of the GPIbbeta ectodomain are replaced by their GPIX counterparts. Like GPIbbeta but unlike GPIX ectodomain, it can secrete from transfected Chinese hamster ovary cells and fold into a stable conformation. Furthermore, replacing the ectodomain in GPIX with the Ibbeta/IX chimera, but not the GPIbbeta ectodomain, preserved its interaction with GPIbbeta as demonstrated by its native-like GPIbbeta-induced increase in surface expression and coimmunoprecipitation. CONCLUSIONS The putative convex surface of the LRR domain in GPIX is sufficient, in the context of full-length subunit, to mediate its association with GPIbbeta.
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Affiliation(s)
- X Mo
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA
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Kunishima S, Sako M, Yamazaki T, Hamaguchi M, Saito H. Molecular genetic analysis of a variant Bernard?Soulier syndrome due to compound heterozygosity for two novel glycoprotein Ib? mutations. Eur J Haematol 2006; 77:501-12. [PMID: 16978236 DOI: 10.1111/j.0902-4441.2006.t01-1-ejh2817.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Bernard-Soulier syndrome (BSS) is a rare bleeding disorder characterized by giant platelets, thrombocytopenia, and prolonged bleeding time. It is caused by abnormalities in the glycoprotein (GP) Ib/IX/V complex, the receptor for von Willebrand factor (vWF). Most cases of BSS described so far involve quantitative rather than qualitative defects in the complex. In this study, we investigated the effects of two naturally occurring mutations in the GPIbbeta gene, C122S and 443delG, on the expression of the GPIb/IX complex identified in a variant type of BSS in which the platelets had severely reduced GPIbalpha ( approximately 10%) and less markedly reduced GPIbbeta and GPIX ( approximately 20%) expression. Immunoblot analysis showed the absence of non-reduced GPIb (GPIbalpha/GPIbbeta) in the patient's platelets. Transient transfection experiments in 293T cells revealed the expression of GPIbbeta Ser122 polypeptide and absence of GPIbbeta 443delG polypeptide. Although no disulfide-linked association was observed between GPIbbeta Ser122 and GPIbalpha, GPIbbeta Ser122 was non-covalently associated with both GPIbalpha and GPIX subunits on the cell surface when cotransfected with wild-type GPIbalpha and GPIX. Chinese hamster ovary cells stably expressing GPIbalpha/Ibbeta Ser122/IX had the ability to bind soluble vWF and to aggregate in the presence of ristocetin. These results suggest that despite disruption of the disulfide linkage between GPIbalpha and GPIbbeta, GPIb/IX is formed, but its stability may be impaired, resulting in low levels of the complex on the platelet membranes.
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Affiliation(s)
- Shinji Kunishima
- Department of Hemostasis and Thrombosis, Clinical Research Center, National Hospital Organization Nagoya Medical Center, Nagoya, Japan.
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Lanza F. Bernard-Soulier syndrome (hemorrhagiparous thrombocytic dystrophy). Orphanet J Rare Dis 2006; 1:46. [PMID: 17109744 PMCID: PMC1660532 DOI: 10.1186/1750-1172-1-46] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2006] [Accepted: 11/16/2006] [Indexed: 11/29/2022] Open
Abstract
Bernard-Soulier syndrome (BSS), also known as Hemorrhagiparous thrombocytic dystrophy, is a hereditary bleeding disorder affecting the megakaryocyte/platelet lineage and characterized by bleeding tendency, giant blood platelets and low platelet counts. This syndrome is extremely rare as only approximately 100 cases have been reported in the literature. Clinical manifestations usually include purpura, epistaxis, menorrhagia, gingival and gastrointestinal bleeding. The syndrome is transmitted as an autosomal recessive trait. The underlying defect is a deficiency or dysfunction of the glycoprotein GPIb-V-IX complex, a platelet-restricted multisubunit receptor required for normal primary hemostasis. The GPIb-V-IX complex binds von Willebrand factor, allowing platelet adhesion and platelet plug formation at sites of vascular injury. Genes coding for the four subunits of the receptor, GPIBA, GPIBB, GP5 and GP9, map to chromosomes 17p12, 22q11.2, 3q29, and 3q21, respectively. Defects have been identified in GPIBA, GPIBB, and GP9 but not in GP5. Diagnosis is based on a prolonged skin bleeding time, the presence of a small number of very large platelets (macrothrombocytopenia), defective ristocetin-induced platelet agglutination and low or absent expression of the GPIb-V-IX complex. Prothrombin consumption is markedly reduced. The prognosis is usually good with adequate supportive care but severe bleeding episodes can occur with menses, trauma and surgical procedures. Treatment of bleeding or prophylaxis during surgical procedures usually requires platelet transfusion.
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Leung MYK, Steinbach PJ, Bear D, Baxendale V, Fechner PY, Rennert OM, Chan WY. Biological effect of a novel mutation in the third leucine-rich repeat of human luteinizing hormone receptor. Mol Endocrinol 2006; 20:2493-503. [PMID: 16709601 DOI: 10.1210/me.2005-0510] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
A novel heterozygous mutation A340T leading to the substitution of Phe for the conserved amino acid Ile114 was identified by nucleotide sequencing of the human LH/chorionic gonadotropin receptor (hLHR) of a patient with Leydig cell hypoplasia. This mutation is located in the third leucine-rich repeat in the ectodomain of the hLHR. In vitro expression studies demonstrated that this mutation results in reduced ligand binding and signal transduction of the receptor. Studies of hLHR constructs in which various amino acids were substituted for the conserved Ile114 showed that receptor activity is sensitive to changes in size, shape, and charge of the side chain. A homology model of the wild-type hLHR ectodomain was made, illustrating the packing of conserved hydrophobic side chains in the protein core. Substitution of Ile114 by Phe might disrupt intermolecular contacts between hormone and receptor. This mutation might also affect an LHR-dimer interaction. Thus, the I114F mutation reduces ligand binding and signal transduction by the hLHR, and it is partially responsible for Leydig cell hypoplasia in the patient.
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Affiliation(s)
- Michael Yiu-Kwong Leung
- Laboratory of Clinical Genomics, National Institute of Child Health and Human Development, National Institutes of Health, Building 49, Room 2A08, 49 Convent Drive, MSC 4429, Bethesda, Maryland 20892-4429, USA
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