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Nitschke NJ, Jelsig AM, Lautrup C, Lundsgaard M, Severinsen MT, Cowland JB, Maroun LL, Andersen MK, Grønbæk K. Expanding the understanding of telomere biology disorder with reports from two families harboring variants in ZCCHC8 and TERC. Clin Genet 2024; 106:187-192. [PMID: 38606545 DOI: 10.1111/cge.14534] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2024] [Revised: 03/04/2024] [Accepted: 04/04/2024] [Indexed: 04/13/2024]
Abstract
Telomere biology disorder (TBD) can present within a wide spectrum of symptoms ranging from severe congenital malformations to isolated organ dysfunction in adulthood. Diagnosing TBD can be challenging given the substantial variation in symptoms and age of onset across generations. In this report, we present two families, one with a pathogenic variant in ZCCHC8 and another with a novel variant in TERC. In the literature, only one family has previously been reported with a ZCCHC8 variant and TBD symptoms. This family had multiple occurrences of pulmonary fibrosis and one case of bone marrow failure. In this paper, we present a second family with the same ZCCHC8 variant (p.Pro186Leu) and symptoms of TBD including pulmonary fibrosis, hematological disease, and elevated liver enzymes. The suspicion of TBD was confirmed with the measurement of short telomeres in the proband. In another family, we report a novel likely pathogenic variant in TERC. Our comprehensive description encompasses hematological manifestations, as well as pulmonary and hepatic fibrosis. Notably, there are no other reports which associate this variant to disease. The families expand our understanding of the clinical implications and genetic causes of TBD.
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Affiliation(s)
- Nikolaj Juul Nitschke
- Department of Hematology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
- Faculty of Health and Medical Sciences, Biotech Research and Innovation Centre (BRIC), University of Copenhagen, Copenhagen, Denmark
| | - Anne Marie Jelsig
- Department of Clinical Genetics, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Charlotte Lautrup
- Department of Clinical Genetics, Aarhus University Hospital, Aarhus, Denmark
- Department of Molecular Medicine, Aarhus University Hospital, Aarhus, Denmark
| | - Malene Lundsgaard
- Department of Clinical Genetics, Aalborg University Hospital, Aalborg, Denmark
| | - Marianne Tang Severinsen
- Department of Hematology, Clinical Cancer Research Center, Aalborg University Hospital, Aalborg, Denmark
- Department of Clinical Medicine, Aalborg University, Aalborg, Denmark
| | - Jack Bernard Cowland
- Department of Clinical Genetics, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Lisa Leth Maroun
- Department of Pathology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Mette Klarskov Andersen
- Department of Clinical Genetics, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Kirsten Grønbæk
- Department of Hematology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
- Faculty of Health and Medical Sciences, Biotech Research and Innovation Centre (BRIC), University of Copenhagen, Copenhagen, Denmark
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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Smolag KI, Fager Ferrari M, Zetterberg E, Leinoe E, Ek T, Blom AM, Rossing M, Martin M. Severe Congenital Thrombocytopenia Characterized by Decreased Platelet Sialylation and Moderate Complement Activation Caused by Novel Compound Heterozygous Variants in GNE. Front Immunol 2021; 12:777402. [PMID: 34858435 PMCID: PMC8630651 DOI: 10.3389/fimmu.2021.777402] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Accepted: 10/22/2021] [Indexed: 11/22/2022] Open
Abstract
Background Hereditary thrombocytopenias constitute a genetically heterogeneous cause of increased bleeding. We report a case of a 17-year-old boy suffering from severe macrothrombocytopenia throughout his life. Whole genome sequencing revealed the presence of two compound heterozygous variants in GNE encoding the enzyme UDP-N-acetyl-glucosamine-2-epimerase/N-acetylmannosamine kinase, crucial for sialic acid biosynthesis. Sialic acid is required for normal platelet life span, and biallelic variants in GNE have previously been associated with isolated macrothrombocytopenia. Furthermore, sialic acid constitutes a key ligand for complement factor H (FH), an important inhibitor of the complement system, protecting host cells from indiscriminate attack. Methods Sialic acid expression and FH binding to platelets and leukocytes was evaluated by flow cytometry. The binding of FH to erythrocytes was assessed indirectly by measuring the rate of complement mediated hemolysis. Complement activation was determined by measuring levels of C3bBbP (alternative pathway), C4d (classical/lectin pathway) and soluble terminal complement complex assays. Results The proband exhibited markedly decreased expression of sialic acid on platelets and leukocytes. Consequently, the binding of FH was strongly reduced and moderate activation of the alternative and classical/lectin complement pathways was observed, together with an increased rate of erythrocyte lysis. Conclusion We report two previously undescribed variants in GNE causing severe congenital macrothrombocytopenia in a compound heterozygous state, as a consequence of decreased platelet sialylation. The decreased sialylation of platelets, leukocytes and erythrocytes affects the binding of FH, leading to moderate complement activation and increased hemolysis.
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Affiliation(s)
- Karolina I Smolag
- Section of Medical Protein Chemistry, Department of Translational Medicine, Lund University, Malmö, Sweden
| | - Marcus Fager Ferrari
- Clinical Coagulation Research Unit, Department of Translational Medicine, Lund University, Malmö, Sweden
| | - Eva Zetterberg
- Clinical Coagulation Research Unit, Department of Translational Medicine, Lund University, Malmö, Sweden
| | - Eva Leinoe
- Department of Hematology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Torben Ek
- Children's Cancer Center, Queen Silvia Children's Hospital, Gothenburg, Sweden
| | - Anna M Blom
- Section of Medical Protein Chemistry, Department of Translational Medicine, Lund University, Malmö, Sweden
| | - Maria Rossing
- Center for Genomic Medicine, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Myriam Martin
- Section of Medical Protein Chemistry, Department of Translational Medicine, Lund University, Malmö, Sweden
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Leinøe E, Brøns N, Rasmussen AØ, Gabrielaite M, Zaninetti C, Palankar R, Zetterberg E, Rosthøj S, Ostrowski SR, Rossing M. The Copenhagen founder variant GP1BA c.58T>G is the most frequent cause of inherited thrombocytopenia in Denmark. J Thromb Haemost 2021; 19:2884-2892. [PMID: 34333846 PMCID: PMC9292710 DOI: 10.1111/jth.15479] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 07/20/2021] [Accepted: 07/29/2021] [Indexed: 12/17/2022]
Abstract
BACKGROUND The classic Bernard-Soulier syndrome (BSS) is a rare inherited thrombocytopenia (IT) associated with severe thrombocytopenia, giant platelets, and bleeding tendency caused by homozygous or compound heterozygous variants in GP1BA, GP1BB, or GP9. Monoallelic BSS (mBSS) associated with mild asymptomatic macrothrombocytopenia caused by heterozygous variants in GP1BA or GP1BB may be a frequent cause of mild IT. OBJECTIVE We aimed to examine the frequency of mBSS in a consecutive cohort of patients with IT and to characterize the geno- and phenotype of mBSS probands and their family members. Additionally, we set out to examine if thrombopoietin (TPO) levels differ in mBSS patients. PATIENTS/METHODS We screened 106 patients suspected of IT using whole exome- or whole genome sequencing and performed co-segregation analyses of mBSS families. All probands and family members were phenotypically characterized. Founder mutation analysis was carried out by certifying that the probands were unrelated and the region around the variant was shared by all patients. TPO was measured by solid phase sandwich ELISA. RESULTS We diagnosed 14 patients (13%) with mBSS associated with heterozygous variants in GP1BA and GP1BB. Six unrelated probands carried a heterozygous variant in GP1BA (c.58T>G, p.Cys20Gly) and shared a 2.0 Mb region on chromosome 17, confirming that it is a founder variant. No discrepancy of TPO levels between mBSS patients and wild-type family members (P > .05) were identified. CONCLUSION We conclude that the most frequent form of IT in Denmark is mBSS caused by the Copenhagen founder variant.
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Affiliation(s)
- Eva Leinøe
- Department of HematologyCopenhagen University HospitalRigshospitaletCopenhagenDenmark
- Center for Genomic MedicineCopenhagen University HospitalRigshospitaletCopenhagenDenmark
| | - Nanna Brøns
- Department of HematologyCopenhagen University HospitalRigshospitaletCopenhagenDenmark
| | | | - Migle Gabrielaite
- Center for Genomic MedicineCopenhagen University HospitalRigshospitaletCopenhagenDenmark
| | - Carlo Zaninetti
- Department of Immunology and Transfusion MedicineUniversity Medicine GreifswaldGreifswaldGermany
| | - Raghavendra Palankar
- Department of Immunology and Transfusion MedicineUniversity Medicine GreifswaldGreifswaldGermany
| | | | - Steen Rosthøj
- Department of PediatricsAalborg University HospitalAalborgDenmark
| | - Sisse Rye Ostrowski
- Department of Clinical ImmunologyCopenhagen University HospitalRigshospitaletCopenhagenDenmark
| | - Maria Rossing
- Center for Genomic MedicineCopenhagen University HospitalRigshospitaletCopenhagenDenmark
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Fager Ferrari M, Zetterberg E, Rossing M, Manon-Jensen T, Pehrsson M, Karsdal MA, Lykkesfeldt J, Leinoe E. Collagen remodelling and plasma ascorbic acid levels in patients suspected of inherited bleeding disorders harbouring germline variants in collagen-related genes. Haemophilia 2020; 27:e69-e77. [PMID: 33161638 PMCID: PMC7894344 DOI: 10.1111/hae.14195] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 10/18/2020] [Accepted: 10/21/2020] [Indexed: 12/04/2022]
Abstract
Introduction Variants in collagen‐related genes COL1A1, COL3A1, COL5A1 and COL5A2 are associated with Ehlers‐Danlos syndrome (EDS), a heterogeneous group of connective tissue disorders strongly associated with increased bleeding. Of patients with incompletely explained bleeding diathesis, a relatively high proportion were shown to harbour at least one heterozygous variant of unknown significance (VUS) in one of these genes, the vast majority without meeting the clinical criteria for EDS. Aim To investigate the functional consequences of the identified variants by assessing the formation and degradation of types I, III and V collagen, in addition to plasma levels of ascorbic acid (AA). Methods A total of 31 patients harbouring at least one heterozygous VUS in COL1A1, COL3A1, COL5A1 or COL5A2 and 20 healthy controls were assessed using monoclonal antibodies targeting neo‐epitopes specific for collagen formation and degradation. Plasma AA levels were measured in patients using high‐performance liquid chromatography. Results Serum levels of C5 M (degradation of type V collagen) were decreased in patients compared with healthy controls (p = .033). No significant differences were found in biomarkers for remodelling of types I and III collagen. A significant negative correlation between bleeding (ISTH‐BAT score) and plasma AA levels was shown (r = −.42; r2 = .17; p = .020). Suboptimal or marginally deficient AA status was found in 8/31 patients (26%). Conclusion Functional investigations of collagen remodelling were not able to identify any clear associations between the identified variants and increased bleeding. The negative correlation between plasma AA levels and ISTH‐BAT score motivates further investigations.
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Affiliation(s)
- Marcus Fager Ferrari
- Clinical Coagulation Research Unit, Department of Translational Medicine, Lund University, Malmö, Sweden
| | - Eva Zetterberg
- Clinical Coagulation Research Unit, Department of Translational Medicine, Lund University, Malmö, Sweden
| | - Maria Rossing
- Center for Genomic Medicine, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | | | - Martin Pehrsson
- Nordic Bioscience A/S, Biomarkers & Research, Herlev, Denmark
| | | | - Jens Lykkesfeldt
- Department of Veterinary & Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg, Denmark
| | - Eva Leinoe
- Department of Hematology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
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Ver Donck F, Downes K, Freson K. Strengths and limitations of high-throughput sequencing for the diagnosis of inherited bleeding and platelet disorders. J Thromb Haemost 2020; 18:1839-1845. [PMID: 32521110 DOI: 10.1111/jth.14945] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 05/27/2020] [Accepted: 05/31/2020] [Indexed: 12/23/2022]
Abstract
Inherited bleeding and platelet disorders (BPD) are highly heterogeneous and their diagnosis involves a combination of clinical investigations, laboratory tests, and genetic screening. This review will outline some of the challenges that geneticists and experts in clinical hemostasis face when implementing high-throughput sequencing (HTS) for patient care. We will provide an overview of the strengths and limitations of the different HTS techniques that can be used to diagnose BPD. An HTS test is cost-efficient and expected to increase the diagnostic rate with a possibility to detect unexpected diagnoses and decrease the turnaround time to diagnose patients. On the other hand, technical shortcomings, variant interpretation difficulties, and ethical issues related to HTS for BPD will also be documented. Delivering a genetic diagnosis to patients is highly desirable to improve clinical management and allow family counseling, but making incorrect assumptions about variants and providing insufficient information to patients before initiating the test could be harmful. Data-sharing and improved HTS guidelines are essential to limit these major drawbacks of HTS.
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Affiliation(s)
- Fabienne Ver Donck
- Department of Cardiovascular Sciences, Center for Molecular and Vascular Biology, University of Leuven, Leuven, Belgium
| | - Kate Downes
- East Midlands and East of England Genomics Laboratory Hub, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK
- Department of Haematology, University of Cambridge, Cambridge, UK
| | - Kathleen Freson
- Department of Cardiovascular Sciences, Center for Molecular and Vascular Biology, University of Leuven, Leuven, Belgium
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Nurden AT, Nurden P. Inherited thrombocytopenias: history, advances and perspectives. Haematologica 2020; 105:2004-2019. [PMID: 32527953 PMCID: PMC7395261 DOI: 10.3324/haematol.2019.233197] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Accepted: 05/08/2020] [Indexed: 12/11/2022] Open
Abstract
Over the last 100 years the role of platelets in hemostatic events and their production by megakaryocytes have gradually been defined. Progressively, thrombocytopenia was recognized as a cause of bleeding, first through an acquired immune disorder; then, since 1948, when Bernard-Soulier syndrome was first described, inherited thrombocytopenia became a fascinating example of Mendelian disease. The platelet count is often severely decreased and platelet size variable; associated platelet function defects frequently aggravate bleeding. Macrothrombocytopenia with variable proportions of enlarged platelets is common. The number of circulating platelets will depend on platelet production, consumption and lifespan. The bulk of macrothrombocytopenias arise from defects in megakaryopoiesis with causal variants in transcription factor genes giving rise to altered stem cell differentiation and changes in early megakaryocyte development and maturation. Genes encoding surface receptors, cytoskeletal and signaling proteins also feature prominently and Sanger sequencing associated with careful phenotyping has allowed their early classification. It quickly became apparent that many inherited thrombocytopenias are syndromic while others are linked to an increased risk of hematologic malignancies. In the last decade, the application of next-generation sequencing, including whole exome sequencing, and the use of gene platforms for rapid testing have greatly accelerated the discovery of causal genes and extended the list of variants in more common disorders. Genes linked to an increased platelet turnover and apoptosis have also been identified. The current challenges are now to use next-generation sequencing in first-step screening and to define bleeding risk and treatment better.
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Affiliation(s)
- Alan T Nurden
- Institut Hospitalo-Universitaire LIRYC, Pessac, France
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Leinoe E, Kjaersgaard M, Zetterberg E, Ostrowski S, Greinacher A, Rossing M. Highly impaired platelet ultrastructure in two families with novel IKZF5 variants. Platelets 2020; 32:492-497. [PMID: 32419556 DOI: 10.1080/09537104.2020.1764921] [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: 10/24/2022]
Abstract
Heterozygous variants in the IKZF5 gene, encoding transcription factor Pegasus, were recently discovered to be causal of inherited thrombocytopenia (IT). We screened 90 patients suspected of inherited thrombocytopenia for variants in 101 genes associated with inherited bleeding disorders and report the clinical presentation of two Danish families with novel variants in IKZF5. Platelet ultrastructure and cytoskeleton were evaluated by immunofluorescent microscopy (IF) and found to be highly abnormal, demonstrating severe disturbances of distribution and expression of non-muscular myosin, filamin, β-tubulin and α tubulin. Number of alpha granules were reduced, and platelets elongated when evaluated by TEM. In both families a child carrying a rare IKZF5 variant was affected by developmental delay. The proband of family A presented with recurrent infections and was examined for an immunodeficiency. The concentration of naive B-cells was found moderately reduced by leucocyte subpopulation examination, indicating an impaired cellular immunity. T-cells were marginally low with reduced share and concentration of CD45RApos, CD31pos, CD4pos recent thymic immigrants as signs of reduced thymic output. The novel IKZF5 variants co-segregated with thrombocytopenia in both families and both probands had significant bleeding tendency. Through comprehensive characterizations of the platelet morphology and function linked to the specific phenotypes we add novel insight to IKZF5-associated thrombocytopenia, which may help to identify and classify more cases with IKZF5 associated IT.
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Affiliation(s)
- Eva Leinoe
- Department of Hematology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Mimi Kjaersgaard
- Department of Pediatrics, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Eva Zetterberg
- Department of Translational Medicine, Lund University, Malmö, Sweden
| | - Sisse Ostrowski
- Department of Clinical Immunology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Andreas Greinacher
- Department of Immunology and Transfusion Medicine, Greifswald University Hospital, Greifswald, Germany
| | - Maria Rossing
- Center for Genomic Medicine, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
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Andersson NG, Rossing M, Fager Ferrari M, Gabrielaite M, Leinøe E, Ljung R, Mårtensson A, Norström E, Zetterberg E. Genetic screening of children with suspected inherited bleeding disorders. Haemophilia 2020; 26:314-324. [DOI: 10.1111/hae.13948] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Revised: 02/07/2020] [Accepted: 02/10/2020] [Indexed: 12/14/2022]
Affiliation(s)
- Nadine G. Andersson
- Department of Clinical Sciences Paediatrics Lund University Lund Sweden
- Centre for Thrombosis and Haemostasis Skåne University Hospital Malmö Sweden
- Department for Paediatric Haematology and Oncology Skåne University Hospital Malmö Sweden
| | - Maria Rossing
- Centre for Genomic Medicine Rigshospitalet Copenhagen University Hospital Copenhagen Denmark
| | - Marcus Fager Ferrari
- Centre for Thrombosis and Haemostasis Skåne University Hospital Malmö Sweden
- Department of Translational Medicine Lund University Malmö Sweden
| | - Migle Gabrielaite
- Centre for Genomic Medicine Rigshospitalet Copenhagen University Hospital Copenhagen Denmark
| | - Eva Leinøe
- Department of Haematology Rigshospitalet Copenhagen University Hospital Copenhagen Denmark
| | - Rolf Ljung
- Department of Clinical Sciences Paediatrics Lund University Lund Sweden
| | - Annika Mårtensson
- Department of Clinical Sciences Paediatrics Lund University Lund Sweden
- Department for Paediatric Haematology and Oncology Skåne University Hospital Malmö Sweden
| | - Eva Norström
- Department for Clinical Chemistry Skåne University Hospital Malmö Sweden
| | - Eva Zetterberg
- Centre for Thrombosis and Haemostasis Skåne University Hospital Malmö Sweden
- Department of Translational Medicine Lund University Malmö Sweden
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