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Rutten JW, Cerfontaine MN, Dijkstra KL, Mulder AA, Vreijling J, Kruit M, Koning RI, de Bot ST, van Nieuwenhuizen KM, Baelde HJ, Berendse HW, Mei LH, Ruijter GJG, Baas F, Jost CR, van Duinen SG, Nibbeling EAR, Gravesteijn G, Lesnik Oberstein SAJ. Bi-allelic NIT1 variants cause a brain small vessel disease characterized by movement disorders, massively dilated perivascular spaces, and intracerebral hemorrhage. Genet Med 2024; 26:101105. [PMID: 38430071 DOI: 10.1016/j.gim.2024.101105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Revised: 02/22/2024] [Accepted: 02/22/2024] [Indexed: 03/03/2024] Open
Abstract
PURPOSE To describe a recessively inherited cerebral small vessel disease, caused by loss-of-function variants in Nitrilase1 (NIT1). METHODS We performed exome sequencing, brain magnetic resonance imaging, neuropathology, electron microscopy, western blotting, and transcriptomic and metabolic analyses in 7 NIT1-small vessel disease patients from 5 unrelated pedigrees. RESULTS The first identified patients were 3 siblings, compound heterozygous for the NIT1 c.727C>T; (p.Arg243Trp) variant and the NIT1 c.198_199del; p.(Ala68∗) variant. The 4 additional patients were single cases from 4 unrelated pedigrees and were all homozygous for the NIT1 c.727C>T; p.(Arg243Trp) variant. Patients presented in mid-adulthood with movement disorders. All patients had striking abnormalities on brain magnetic resonance imaging, with numerous and massively dilated basal ganglia perivascular spaces. Three patients had non-lobar intracerebral hemorrhage between age 45 and 60, which was fatal in 2 cases. Western blotting on patient fibroblasts showed absence of NIT1 protein, and metabolic analysis in urine confirmed loss of NIT1 enzymatic function. Brain autopsy revealed large electron-dense deposits in the vessel walls of small and medium sized cerebral arteries. CONCLUSION NIT1-small vessel disease is a novel, autosomal recessively inherited cerebral small vessel disease characterized by a triad of movement disorders, massively dilated basal ganglia perivascular spaces, and intracerebral hemorrhage.
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Affiliation(s)
- Julie W Rutten
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands.
| | - Minne N Cerfontaine
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Kyra L Dijkstra
- Department of Pathology, Leiden University Medical Center, Leiden, The Netherlands
| | - Aat A Mulder
- Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, The Netherlands
| | - Jeroen Vreijling
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Mark Kruit
- Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Roman I Koning
- Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, The Netherlands
| | - Susanne T de Bot
- Department of Neurology, Leiden University Medical Center, Leiden, The Netherlands
| | | | - Hans J Baelde
- Department of Pathology, Leiden University Medical Center, Leiden, The Netherlands
| | - Henk W Berendse
- Department of Neurology, Amsterdam University Medical Center, location Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Leon H Mei
- Department of Biomedical Data Sciences, Leiden University Medical Center, Leiden, The Netherlands
| | - George J G Ruijter
- Department of Clinical Genetics, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Frank Baas
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Carolina R Jost
- Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, The Netherlands
| | - Sjoerd G van Duinen
- Department of Pathology, Leiden University Medical Center, Leiden, The Netherlands
| | - Esther A R Nibbeling
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Gido Gravesteijn
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands
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van Slobbe M, van Haeringen A, Vissers LELM, Bijlsma EK, Rutten JW, Suerink M, Nibbeling EAR, Ruivenkamp CAL, Koene S. Reanalysis of whole-exome sequencing (WES) data of children with neurodevelopmental disorders in a standard patient care context. Eur J Pediatr 2024; 183:345-355. [PMID: 37889289 PMCID: PMC10858114 DOI: 10.1007/s00431-023-05279-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Revised: 09/20/2023] [Accepted: 10/11/2023] [Indexed: 10/28/2023]
Abstract
This study aims to inform future genetic reanalysis management by evaluating the yield of whole-exome sequencing (WES) reanalysis in standard patient care in the Netherlands. Single-center data of 159 patients with a neurodevelopmental disorder (NDD), in which WES analysis and reanalysis were performed between January 1, 2014, and December 31, 2021, was retrospectively collected. Patients were included if they were under the age of 18 years at initial analysis and if this initial analysis did not result in a diagnosis. Demographic, phenotypic, and genotypic characteristics of patients were collected and analyzed. The primary outcomes of our study were (i) diagnostic yield at reanalysis, (ii) reasons for detecting a new possibly causal variant at reanalysis, (iii) unsolicited findings, and (iv) factors associated with positive result of reanalysis. In addition, we conducted a questionnaire study amongst the 7 genetic department in the Netherlands creating an overview of used techniques, yield, and organization of WES reanalysis. The single-center data show that in most cases, WES reanalysis was initiated by the clinical geneticist (65%) or treating physician (30%). The mean time between initial WES analysis and reanalysis was 3.7 years. A new (likely) pathogenic variant or VUS with a clear link to the phenotype was found in 20 initially negative cases, resulting in a diagnostic yield of 12.6%. In 75% of these patients, the diagnosis had clinical consequences, as for example, a screening plan for associated signs and symptoms could be devised. Most (32%) of the (likely) causal variants identified at WES reanalysis were discovered due to a newly described gene-disease association. In addition to the 12.6% diagnostic yield based on new diagnoses, reclassification of a variant of uncertain significance found at initial analysis led to a definite diagnosis in three patients. Diagnostic yield was higher in patients with dysmorphic features compared to patients without clear dysmorphic features (yield 27% vs. 6%; p = 0.001). CONCLUSIONS Our results show that WES reanalysis in patients with NDD in standard patient care leads to a substantial increase in genetic diagnoses. In the majority of newly diagnosed patients, the diagnosis had clinical consequences. Knowledge about the clinical impact of WES reanalysis, clinical characteristics associated with higher yield, and the yield per year after a negative WES in larger clinical cohorts is warranted to inform guidelines for genetic reanalysis. These guidelines will be of great value for pediatricians, pediatric rehabilitation specialists, and pediatric neurologists in daily care of patients with NDD. WHAT IS KNOWN • Whole exome sequencing can cost-effectively identify a genetic cause of intellectual disability in about 30-40% of patients. • WES reanalysis in a research setting can lead to a definitive diagnosis in 10-20% of previously exome negative cases. WHAT IS NEW • WES reanalysis in standard patient care resulted in a diagnostic yield of 13% in previously exome negative children with NDD. • The presence of dysmorphic features is associated with an increased diagnostic yield of WES reanalysis.
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Affiliation(s)
- Michelle van Slobbe
- Department of Clinical Genetics, Leiden University Medical Centre, Leiden, The Netherlands
| | - Arie van Haeringen
- Department of Clinical Genetics, Leiden University Medical Centre, Leiden, The Netherlands
| | - Lisenka E L M Vissers
- Department of Human Genetics, Donders Centre for Neuroscience, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Emilia K Bijlsma
- Department of Clinical Genetics, Leiden University Medical Centre, Leiden, The Netherlands
| | - Julie W Rutten
- Department of Clinical Genetics, Leiden University Medical Centre, Leiden, The Netherlands
| | - Manon Suerink
- Department of Clinical Genetics, Leiden University Medical Centre, Leiden, The Netherlands
| | - Esther A R Nibbeling
- Department of Clinical Genetics, Leiden University Medical Centre, Leiden, The Netherlands
| | - Claudia A L Ruivenkamp
- Department of Clinical Genetics, Leiden University Medical Centre, Leiden, The Netherlands
| | - Saskia Koene
- Department of Clinical Genetics, Leiden University Medical Centre, Leiden, The Netherlands.
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Bosch E, Popp B, Güse E, Skinner C, van der Sluijs PJ, Maystadt I, Pinto AM, Renieri A, Bruno LP, Granata S, Marcelis C, Baysal Ö, Hartwich D, Holthöfer L, Isidor B, Cogne B, Wieczorek D, Capra V, Scala M, De Marco P, Ognibene M, Jamra RA, Platzer K, Carter LB, Kuismin O, van Haeringen A, Maroofian R, Valenzuela I, Cuscó I, Martinez-Agosto JA, Rabani AM, Mefford HC, Pereira EM, Close C, Anyane-Yeboa K, Wagner M, Hannibal MC, Zacher P, Thiffault I, Beunders G, Umair M, Bhola PT, McGinnis E, Millichap J, van de Kamp JM, Prijoles EJ, Dobson A, Shillington A, Graham BH, Garcia EJ, Galindo MK, Ropers FG, Nibbeling EAR, Hubbard G, Karimov C, Goj G, Bend R, Rath J, Morrow MM, Millan F, Salpietro V, Torella A, Nigro V, Kurki M, Stevenson RE, Santen GWE, Zweier M, Campeau PM, Severino M, Reis A, Accogli A, Vasileiou G. Elucidating the clinical and molecular spectrum of SMARCC2-associated NDD in a cohort of 65 affected individuals. Genet Med 2023; 25:100950. [PMID: 37551667 DOI: 10.1016/j.gim.2023.100950] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Revised: 08/01/2023] [Accepted: 08/01/2023] [Indexed: 08/09/2023] Open
Abstract
PURPOSE Coffin-Siris and Nicolaides-Baraitser syndromes are recognizable neurodevelopmental disorders caused by germline variants in BAF complex subunits. The SMARCC2 BAFopathy was recently reported. Herein, we present clinical and molecular data on a large cohort. METHODS Clinical symptoms for 41 novel and 24 previously published affected individuals were analyzed using the Human Phenotype Ontology. For genotype-phenotype correlations, molecular data were standardized and grouped into non-truncating and likely gene-disrupting (LGD) variants. Missense variant protein expression and BAF-subunit interactions were examined using 3D protein modeling, co-immunoprecipitation, and proximity-ligation assays. RESULTS Neurodevelopmental delay with intellectual disability, muscular hypotonia, and behavioral disorders were the major manifestations. Clinical hallmarks of BAFopathies were rare. Clinical presentation differed significantly, with LGD variants being predominantly inherited and associated with mildly reduced or normal cognitive development, whereas non-truncating variants were mostly de novo and presented with severe developmental delay. These distinct manifestations and non-truncating variant clustering in functional domains suggest different pathomechanisms. In vitro testing showed decreased protein expression for N-terminal missense variants similar to LGD. CONCLUSION This study improved SMARCC2 variant classification and identified discernible SMARCC2-associated phenotypes for LGD and non-truncating variants, which were distinct from other BAFopathies. The pathomechanism of most non-truncating variants has yet to be investigated.
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Affiliation(s)
- Elisabeth Bosch
- Institute of Human Genetics, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Bernt Popp
- Berlin Institute of Health at Charitè, Universitätsklinikum Berlin, Centre of Functional Genomics, Berlin, Germany; Institute of Human Genetics, University of Leipzig Medical Center, Leipzig, Germany
| | - Esther Güse
- Institute of Human Genetics, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | | | | | - Isabelle Maystadt
- Center for Human Genetics, Institute of Pathology and Genetics, Gosselies, Belgium
| | - Anna Maria Pinto
- Genetica Medica, Azienda Ospedaliera Universitaria Senese, Siena, Italy
| | - Alessandra Renieri
- Genetica Medica, Azienda Ospedaliera Universitaria Senese, Siena, Italy; Medical Genetics Unit, University of Siena, Siena, Italy
| | - Lucia Pia Bruno
- Telethon Institute of Genetics and Medicine (TIGEM), Naples, Italy
| | - Stefania Granata
- Genetica Medica, Azienda Ospedaliera Universitaria Senese, Siena, Italy; Medical Genetics Unit, University of Siena, Siena, Italy
| | - Carlo Marcelis
- Human Genetics department, Radboud university medical center, Nijmegen, The Netherlands
| | - Özlem Baysal
- Human Genetics department, Radboud university medical center, Nijmegen, The Netherlands
| | - Dewi Hartwich
- Institute of Human Genetics - University Medical Center of the Johannes Gutenberg University Mainz, Germany
| | - Laura Holthöfer
- Institute of Human Genetics - University Medical Center of the Johannes Gutenberg University Mainz, Germany
| | - Bertrand Isidor
- Nantes Université, CHU de Nantes, Service de Génétique médicale, Nantes, France; Nantes Université, CHU de Nantes, CNRS, INSERM, l'institut du thorax, Nantes, France
| | - Benjamin Cogne
- Nantes Université, CHU de Nantes, Service de Génétique médicale, Nantes, France; Nantes Université, CHU de Nantes, CNRS, INSERM, l'institut du thorax, Nantes, France
| | - Dagmar Wieczorek
- Institute of Human Genetics, Medical Faculty and University Hospital Düsseldorf, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
| | - Valeria Capra
- Genomics and Clinical Genetics Unit, IRCCS Istituto Giannina Gaslini, Genoa, Italy
| | - Marcello Scala
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, Genoa, Italy; Medical Genetics Unit, IRCCS Istituto Giannina Gaslini, Genoa, Italy
| | - Patrizia De Marco
- Medical Genetics Unit, IRCCS Istituto Giannina Gaslini, Genoa, Italy
| | - Marzia Ognibene
- Medical Genetics Unit, IRCCS Istituto Giannina Gaslini, Genoa, Italy
| | - Rami Abou Jamra
- Institute of Human Genetics, University of Leipzig Medical Center, Leipzig, Germany
| | - Konrad Platzer
- Institute of Human Genetics, University of Leipzig Medical Center, Leipzig, Germany
| | - Lauren B Carter
- Department of Pediatrics, Division of Medical Genetics, Levine Children's Hospital, Atrium Health, Charlotte, NC
| | - Outi Kuismin
- Department of Clinical Genetics, Research Unit of Clinical Medicine, Medical Research Center Oulu, Oulu University Hospital and University of Oulu, Oulu, Finland
| | - Arie van Haeringen
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Reza Maroofian
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, University College London, London, United Kingdom
| | - Irene Valenzuela
- Department of Clinical and Molecular Genetics, University Hospital Vall d'Hebron, Barcelona, Spain; Medicine Genetics Group, Valle Hebron Research Institute, Barcelona, Spain
| | - Ivon Cuscó
- Department of Clinical and Molecular Genetics, University Hospital Vall d'Hebron, Barcelona, Spain; Medicine Genetics Group, Valle Hebron Research Institute, Barcelona, Spain
| | - Julian A Martinez-Agosto
- Departments of Human Genetics, Pediatrics, and Psychiatry, UCLA David Geffen School of Medicine, Los Angeles, CA
| | - Ahna M Rabani
- Department of Pediatrics & Institute for Precision Health, UCLA David Geffen School of Medicine, Los Angeles, CA
| | - Heather C Mefford
- Center for Pediatric Neurological Disease Research, St. Jude Children's Research Hospital, Memphis, TN
| | - Elaine M Pereira
- Division of Clinical Genetics, Department of Pediatrics, Columbia University Irving Medical Center, New York, NY
| | - Charlotte Close
- Division of Clinical Genetics, Department of Pediatrics, Columbia University Irving Medical Center, New York, NY
| | - Kwame Anyane-Yeboa
- Division of Clinical Genetics, Department of Pediatrics, Columbia University Irving Medical Center, New York, NY
| | - Mallory Wagner
- Division of Pediatric Genetics, Metabolism, and Genomic Medicine, Department of Pediatrics, University of Michigan Health System, University of Michigan, Ann Arbor, MI
| | - Mark C Hannibal
- Division of Pediatric Genetics, Metabolism, and Genomic Medicine, Department of Pediatrics, University of Michigan Health System, University of Michigan, Ann Arbor, MI
| | - Pia Zacher
- Epilepsy Center Kleinwachau, Radeberg, Germany
| | - Isabelle Thiffault
- Department of Pediatrics and Pathology, Genomic Medicine Center, Children's Mercy Kansas City and Children's Mercy Research Institute, Kansas City, MO
| | - Gea Beunders
- Department of Genetics, University Medical Center Groningen, Groningen, The Netherlands
| | - Muhammad Umair
- Medical Genomics Research Department, King Abdullah International Medical Research Center (KAIMRC), King Saud Bin Abdulaziz University for Health Sciences, King Abdulaziz Medical City, MNGHA, Riyadh, Saudi Arabia; Department of Life Sciences, School of Science, University of Management and Technology (UMT), Lahore, Pakistan
| | - Priya T Bhola
- Department of Genetics, Children's Hospital of Eastern Ontario (CHEO), Ottawa, Canada
| | - Erin McGinnis
- Division of Neurology, Department of Pediatrics, Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, IL
| | - John Millichap
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL
| | - Jiddeke M van de Kamp
- Department of Human Genetics, Amsterdam UMC, location VU Medical Center, Amsterdam, The Netherlands
| | | | | | - Amelle Shillington
- Department of Human Genetics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH
| | - Brett H Graham
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN
| | - Evan-Jacob Garcia
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN
| | | | - Fabienne G Ropers
- Willem-Alexander Children's Hospital, Department of Pediatrics, Leiden University Medical Center, The Netherlands
| | - Esther A R Nibbeling
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Gail Hubbard
- Department of Medical Genetics, Children's Hospital Los Angeles, Keck School of Medicine of University of Southern California, Los Angeles, CA
| | - Catherine Karimov
- Department of Medical Genetics, Children's Hospital Los Angeles, Keck School of Medicine of University of Southern California, Los Angeles, CA
| | - Guido Goj
- Vestische Kinder- und Jugendklinik, Datteln, Germany
| | - Renee Bend
- PreventionGenetics, Part of Exact Sciences, Marshfield, WI
| | - Julie Rath
- PreventionGenetics, Part of Exact Sciences, Marshfield, WI
| | | | | | - Vincenzo Salpietro
- Department of Neuromuscular Disorders, Queen Square Institute of Neurology, University College London, London, United Kingdom; Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, L'Aquila, Italy
| | - Annalaura Torella
- Telethon Institute of Genetics and Medicine (TIGEM), Naples, Italy; Department of Precision Medicine, University of Campania "Luigi Vanvitelli," Naples, Italy
| | - Vincenzo Nigro
- Telethon Institute of Genetics and Medicine (TIGEM), Naples, Italy; Department of Precision Medicine, University of Campania "Luigi Vanvitelli," Naples, Italy
| | - Mitja Kurki
- Institute for Molecular Medicine Finland (FIMM), Helsinki Institute of Life Science (HiLIFE), University of Helsinki, Helsinki, Finland; Program in Medical and Population Genetics, Broad Institute of Harvard and MIT, Cambridge, MA
| | | | - Gijs W E Santen
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Markus Zweier
- Institute of Medical Genetics, University of Zürich, Schlieren-Zurich, Switzerland
| | - Philippe M Campeau
- Department of Pediatrics, CHU Sainte-Justine and University of Montreal, Montreal, QC, Canada
| | | | - André Reis
- Institute of Human Genetics, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany; Centre for Rare Diseases Erlangen (ZSEER), Erlangen, Germany
| | - Andrea Accogli
- Department of Specialized Medicine, Division of Medical Genetics, McGill University Health Centre; Department of Human Genetics, Faculty of Medicine, McGill University, Montreal, QC, Canada
| | - Georgia Vasileiou
- Institute of Human Genetics, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany; Centre for Rare Diseases Erlangen (ZSEER), Erlangen, Germany.
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Atmar K, Ruivenkamp CAL, Hooimeijer L, Nibbeling EAR, Eckhardt CL, Huisman EJ, Lankester AC, Bartels M, Santen GWE, Smiers FJ, van der Burg M, Mohseny AB. Diagnostic Value of a Protocolized In-Depth Evaluation of Pediatric Bone Marrow Failure: A Multi-Center Prospective Cohort Study. Front Immunol 2022; 13:883826. [PMID: 35572556 PMCID: PMC9094492 DOI: 10.3389/fimmu.2022.883826] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [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: 02/25/2022] [Accepted: 03/29/2022] [Indexed: 11/13/2022] Open
Abstract
Background Severe multilineage cytopenia in childhood caused by bone marrow failure (BMF) often represents a serious condition requiring specific management. Patients are at risk for invasive infections and bleeding complications. Previous studies report low rates of identifiable causes of pediatric BMF, rendering most patients with a descriptive diagnosis such as aplastic anemia (AA). Methods We conducted a multi-center prospective cohort study in which an extensive diagnostic approach for pediatric patients with suspected BMF was implemented. After exclusion of malignant and transient causes of BMF, patients entered thorough diagnostic evaluation including bone marrow analysis, whole exome sequencing (WES) including copy number variation (CNV) analysis and/or single nucleotide polymorphisms (SNP) array analysis. In addition, functional and immunological evaluation were performed. Here we report the outcomes of the first 50 patients (2017-2021) evaluated by this approach. Results In 20 patients (40%) a causative diagnosis was made. In this group, 18 diagnoses were established by genetic analysis, including 14 mutations and 4 chromosomal deletions. The 2 remaining patients had short telomeres while no causative genetic defect was found. Of the remaining 30 patients (60%), 21 were diagnosed with severe aplastic anemia (SAA) based on peripheral multi-lineage cytopenia and hypoplastic bone marrow, and 9 were classified as unexplained cytopenia without bone marrow hypoplasia. In total 28 patients had undergone hematopoietic stem cell transplantation (HSCT) of which 22 patients with an unknown cause and 6 patients with an identified cause for BMF. Conclusion We conclude that a standardized in-depth diagnostic protocol as presented here, can increase the frequency of identifiable causes within the heterogeneous group of pediatric BMF. We underline the importance of full genetic analysis complemented by functional tests of all patients as genetic causes are not limited to patients with typical (syndromal) clinical characteristics beyond cytopenia. In addition, it is of importance to apply genome wide genetic analysis, since defects in novel genes are frequently discovered in this group. Identification of a causal abnormality consequently has implications for the choice of treatment and in some cases prevention of invasive therapies.
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Affiliation(s)
- Khaled Atmar
- Department of Pediatric Hematology and Stem Cell Transplantation, Willem-Alexander Children's Hospital, Leiden University Medical Center, Leiden, Netherlands
| | | | - Louise Hooimeijer
- Department of Pediatric Hematology, Beatrix Children's Hospital, University Medical Center Groningen, Groningen, Netherlands
| | - Esther A R Nibbeling
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, Netherlands
| | - Corien L Eckhardt
- Department of Pediatric Hematology, Amsterdam University Medical Center, Amsterdam, Netherlands
| | - Elise J Huisman
- Department of Pediatric Hematology, Erasmus Medical Center, Sophia Children's Hospital, Rotterdam, Netherlands
| | - Arjan C Lankester
- Department of Pediatric Hematology and Stem Cell Transplantation, Willem-Alexander Children's Hospital, Leiden University Medical Center, Leiden, Netherlands
| | - Marije Bartels
- Department of Pediatric Hematology, Wilhelmina Children's Hospital, University Medical Center Utrecht, Utrecht, Netherlands
| | - Gijs W E Santen
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, Netherlands
| | - Frans J Smiers
- Department of Pediatric Hematology and Stem Cell Transplantation, Willem-Alexander Children's Hospital, Leiden University Medical Center, Leiden, Netherlands
| | - Mirjam van der Burg
- Department of Pediatric Hematology and Stem Cell Transplantation, Willem-Alexander Children's Hospital, Leiden University Medical Center, Leiden, Netherlands
| | - Alexander B Mohseny
- Department of Pediatric Hematology and Stem Cell Transplantation, Willem-Alexander Children's Hospital, Leiden University Medical Center, Leiden, Netherlands
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5
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de Koning MA, Hoffer MJV, Nibbeling EAR, Bijlsma EK, Toirkens MJP, Adama-Scheltema PN, Verweij EJ, Veenhof MB, Santen GWE, Peeters-Scholte CMPCD. Prenatal exome sequencing: A useful tool for the fetal neurologist. Clin Genet 2021; 101:65-77. [PMID: 34611884 PMCID: PMC9297851 DOI: 10.1111/cge.14070] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [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: 05/18/2021] [Revised: 09/29/2021] [Accepted: 10/02/2021] [Indexed: 01/08/2023]
Abstract
Prenatal exome sequencing (pES) is a promising tool for diagnosing genetic disorders when structural anomalies are detected on prenatal ultrasound. The aim of this study was to investigate the diagnostic yield and clinical impact of pES as an additional modality for fetal neurologists who counsel parents in case of congenital anomalies of the central nervous system (CNS). We assessed 20 pregnancies of 19 couples who were consecutively referred to the fetal neurologist for CNS anomalies. pES had a diagnostic yield of 53% (10/19) with most diagnosed pregnancies having agenesis or hypoplasia of the corpus callosum (7/10). Overall clinical impact was 63% (12/19), of which the pES result aided parental decision making in 55% of cases (6/11), guided perinatal management in 75% of cases (3/4), and was helpful in approving a late termination of pregnancy request in 75% of cases (3/4). Our data suggest that pES had a high diagnostic yield when CNS anomalies are present, although this study is limited by its small sample size. Moreover, pES had substantial clinical impact, which warrants implementation of pES in the routine care of the fetal neurologist in close collaboration with gynecologists and clinical geneticists.
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Affiliation(s)
- Maayke A de Koning
- Department of Clinical Genetics, Leiden University Medical Centre, Leiden, The Netherlands
| | - Mariëtte J V Hoffer
- Department of Clinical Genetics, Leiden University Medical Centre, Leiden, The Netherlands
| | - Esther A R Nibbeling
- Department of Clinical Genetics, Leiden University Medical Centre, Leiden, The Netherlands
| | - Emilia K Bijlsma
- Department of Clinical Genetics, Leiden University Medical Centre, Leiden, The Netherlands
| | - Menno J P Toirkens
- Department of Radiology, Leiden University Medical Centre, Leiden, The Netherlands
| | | | - E Joanne Verweij
- Department of Obstetrics, Leiden University Medical Centre, Leiden, The Netherlands
| | - Marieke B Veenhof
- Department of Obstetrics, Leiden University Medical Centre, Leiden, The Netherlands
| | - Gijs W E Santen
- Department of Clinical Genetics, Leiden University Medical Centre, Leiden, The Netherlands
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6
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Huang M, Nibbeling EAR, Lagrand TJ, Souza IA, Groen JL, Gandini MA, Zhang FX, Koelman JHTM, Adir N, Sinke RJ, Zamponi GW, Tijssen MAJ, Verbeek DS. Rare functional missense variants in CACNA1H: What can we learn from Writer's cramp? Mol Brain 2021; 14:18. [PMID: 33478561 PMCID: PMC7819179 DOI: 10.1186/s13041-021-00736-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [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: 12/02/2020] [Accepted: 01/13/2021] [Indexed: 11/10/2022] Open
Abstract
Writer's cramp (WC) is a task-specific focal dystonia that occurs selectively in the hand and arm during writing. Previous studies have shown a role for genetics in the pathology of task-specific focal dystonia. However, to date, no causal gene has been reported for task-specific focal dystonia, including WC. In this study, we investigated the genetic background of a large Dutch family with autosomal dominant‒inherited WC that was negative for mutations in known dystonia genes. Whole exome sequencing identified 4 rare variants of unknown significance that segregated in the family. One candidate gene was selected for follow-up, Calcium Voltage-Gated Channel Subunit Alpha1 H, CACNA1H, due to its links with the known dystonia gene Potassium Channel Tetramerization Domain Containing 17, KCTD17, and with paroxysmal movement disorders. Targeted resequencing of CACNA1H in 82 WC cases identified another rare, putative damaging variant in a familial WC case that did not segregate. Using structural modelling and functional studies in vitro, we show that both the segregating p.Arg481Cys variant and the non-segregating p.Glu1881Lys variant very likely cause structural changes to the Cav3.2 protein and lead to similar gains of function, as seen in an accelerated recovery from inactivation. Both mutant channels are thus available for re-activation earlier, which may lead to an increase in intracellular calcium and increased neuronal excitability. Overall, we conclude that rare functional variants in CACNA1H need to be interpreted very carefully, and additional studies are needed to prove that the p.Arg481Cys variant is the cause of WC in the large Dutch family.
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Affiliation(s)
- Miaozhen Huang
- Department of Genetics, University Medical Center Groningen, University of Groningen, P.O. box 30 001, 9700 RB, Groningen, The Netherlands
| | - Esther A R Nibbeling
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Tjerk J Lagrand
- Department of Neurology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Ivana A Souza
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, Alberta Children's Hospital Research Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Justus L Groen
- Department of Neurosurgery, Leiden University Medical Centre, Leiden, The Netherlands
| | - Maria A Gandini
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Fang-Xiong Zhang
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Johannes H T M Koelman
- Department of Neurology and Clinical Neurophysiology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Noam Adir
- Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Technion, Israel
| | - Richard J Sinke
- Department of Genetics, University Medical Center Groningen, University of Groningen, P.O. box 30 001, 9700 RB, Groningen, The Netherlands
| | - Gerald W Zamponi
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Marina A J Tijssen
- Department of Neurology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Dineke S Verbeek
- Department of Genetics, University Medical Center Groningen, University of Groningen, P.O. box 30 001, 9700 RB, Groningen, The Netherlands.
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7
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de Koning MA, Haak MC, Adama van Scheltema PN, Peeters-Scholte CMPCD, Koopmann TT, Nibbeling EAR, Aten E, den Hollander NS, Ruivenkamp CAL, Hoffer MJV, Santen GWE. From diagnostic yield to clinical impact: a pilot study on the implementation of prenatal exome sequencing in routine care. Genet Med 2019; 21:2303-2310. [PMID: 30918357 DOI: 10.1038/s41436-019-0499-9] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Accepted: 03/14/2019] [Indexed: 12/29/2022] Open
Abstract
PURPOSE Exome sequencing (ES) is an efficient tool to diagnose genetic disorders postnatally. Recent studies show that it may have a considerable diagnostic yield in fetuses with structural anomalies on ultrasound. We report on the clinical impact of the implementation of prenatal ES (pES) for ongoing pregnancies in routine care. METHODS We retrospectively analyzed the impact of pES on pregnancy outcome and pre- or perinatal management in the first 22 patients counseled for pES because of one or more structural anomalies on fetal ultrasound. RESULTS In two cases, a diagnosis was made by chromosomal microarray analysis after ES counseling. The remaining 20 cases were divided in three groups: (1) pES to aid parental decision making (n = 12), (2) pES in the context of late pregnancy termination requests (n = 5), and (3) pES to guide pre- or perinatal management (n = 3). pES had a clinical impact in 75% (9/12), 40% (2/5), and 100% (3/3) respectively, showing an overall clinical impact of pES of 70% (14/20). CONCLUSION We show that clinical implementation of pES is feasible and affects parental decision making or pre- and perinatal management supporting further implementation of ES in the prenatal setting.
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Affiliation(s)
- Maayke A de Koning
- Department of Clinical Genetics, Leiden University Medical Centre, Leiden, the Netherlands
| | - Monique C Haak
- Department of Obstetrics and Fetal Medicine, Leiden University Medical Centre, Leiden, the Netherlands
| | | | | | - Tamara T Koopmann
- Department of Clinical Genetics, Leiden University Medical Centre, Leiden, the Netherlands
| | - Esther A R Nibbeling
- Department of Clinical Genetics, Leiden University Medical Centre, Leiden, the Netherlands
| | - Emmelien Aten
- Department of Clinical Genetics, Leiden University Medical Centre, Leiden, the Netherlands
| | | | - Claudia A L Ruivenkamp
- Department of Clinical Genetics, Leiden University Medical Centre, Leiden, the Netherlands
| | - Mariëtte J V Hoffer
- Department of Clinical Genetics, Leiden University Medical Centre, Leiden, the Netherlands
| | - Gijs W E Santen
- Department of Clinical Genetics, Leiden University Medical Centre, Leiden, the Netherlands.
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8
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Nibbeling EAR, Duarri A, Verschuuren-Bemelmans CC, Fokkens MR, Karjalainen JM, Smeets CJLM, de Boer-Bergsma JJ, van der Vries G, Dooijes D, Bampi GB, van Diemen C, Brunt E, Ippel E, Kremer B, Vlak M, Adir N, Wijmenga C, van de Warrenburg BPC, Franke L, Sinke RJ, Verbeek DS. Exome sequencing and network analysis identifies shared mechanisms underlying spinocerebellar ataxia. Brain 2017; 140:2860-2878. [PMID: 29053796 DOI: 10.1093/brain/awx251] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Accepted: 08/05/2017] [Indexed: 12/17/2022] Open
Abstract
The autosomal dominant cerebellar ataxias, referred to as spinocerebellar ataxias in genetic nomenclature, are a rare group of progressive neurodegenerative disorders characterized by loss of balance and coordination. Despite the identification of numerous disease genes, a substantial number of cases still remain without a genetic diagnosis. Here, we report five novel spinocerebellar ataxia genes, FAT2, PLD3, KIF26B, EP300, and FAT1, identified through a combination of exome sequencing in genetically undiagnosed families and targeted resequencing of exome candidates in a cohort of singletons. We validated almost all genes genetically, assessed damaging effects of the gene variants in cell models and further consolidated a role for several of these genes in the aetiology of spinocerebellar ataxia through network analysis. Our work links spinocerebellar ataxia to alterations in synaptic transmission and transcription regulation, and identifies these as the main shared mechanisms underlying the genetically diverse spinocerebellar ataxia types.
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Affiliation(s)
- Esther A R Nibbeling
- Department of Genetics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Anna Duarri
- Department of Genetics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | | | - Michiel R Fokkens
- Department of Genetics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Juha M Karjalainen
- Department of Genetics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Cleo J L M Smeets
- Department of Genetics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Jelkje J de Boer-Bergsma
- Department of Genetics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Gerben van der Vries
- Department of Genetics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Dennis Dooijes
- Department of Medical Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Giovana B Bampi
- Department of Genetics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Cleo van Diemen
- Department of Genetics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Ewout Brunt
- Department of Neurology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Elly Ippel
- Department of Medical Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Berry Kremer
- Department of Neurology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Monique Vlak
- Department of Neurology, Medical Center Haaglanden and Bronovo-Nebo, Den Hague, The Netherlands
| | - Noam Adir
- Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Technion City, Israel
| | - Cisca Wijmenga
- Department of Genetics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | | | - Lude Franke
- Department of Genetics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Richard J Sinke
- Department of Genetics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Dineke S Verbeek
- Department of Genetics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
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9
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Nibbeling EAR, Delnooz CCS, de Koning TJ, Sinke RJ, Jinnah HA, Tijssen MAJ, Verbeek DS. Using the shared genetics of dystonia and ataxia to unravel their pathogenesis. Neurosci Biobehav Rev 2017; 75:22-39. [PMID: 28143763 DOI: 10.1016/j.neubiorev.2017.01.033] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Revised: 12/09/2016] [Accepted: 01/24/2017] [Indexed: 12/13/2022]
Abstract
In this review we explore the similarities between spinocerebellar ataxias and dystonias, and suggest potentially shared molecular pathways using a gene co-expression network approach. The spinocerebellar ataxias are a group of neurodegenerative disorders characterized by coordination problems caused mainly by atrophy of the cerebellum. The dystonias are another group of neurological movement disorders linked to basal ganglia dysfunction, although evidence is now pointing to cerebellar involvement as well. Our gene co-expression network approach identified 99 shared genes and showed the involvement of two major pathways: synaptic transmission and neurodevelopment. These pathways overlapped in the two disorders, with a large role for GABAergic signaling in both. The overlapping pathways may provide novel targets for disease therapies. We need to prioritize variants obtained by whole exome sequencing in the genes associated with these pathways in the search for new pathogenic variants, which can than be used to help in the genetic counseling of patients and their families.
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Affiliation(s)
- Esther A R Nibbeling
- University of Groningen, University Medical Center Groningen, Department of Genetics, Groningen, The Netherlands
| | - Cathérine C S Delnooz
- University of Groningen, University Medical Center Groningen, Department of Neurology, Groningen, The Netherlands
| | - Tom J de Koning
- University of Groningen, University Medical Center Groningen, Department of Genetics, Groningen, The Netherlands; University of Groningen, University Medical Center Groningen, Department of Neurology, Groningen, The Netherlands
| | - Richard J Sinke
- University of Groningen, University Medical Center Groningen, Department of Genetics, Groningen, The Netherlands
| | - Hyder A Jinnah
- Departments of Neurology, Human Genetics and Pediatrics, Emory Clinic, Atlanta, USA
| | - Marina A J Tijssen
- University of Groningen, University Medical Center Groningen, Department of Neurology, Groningen, The Netherlands
| | - Dineke S Verbeek
- University of Groningen, University Medical Center Groningen, Department of Genetics, Groningen, The Netherlands.
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10
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Duarri A, Lin MCA, Fokkens MR, Meijer M, Smeets CJLM, Nibbeling EAR, Boddeke E, Sinke RJ, Kampinga HH, Papazian DM, Verbeek DS. Spinocerebellar ataxia type 19/22 mutations alter heterocomplex Kv4.3 channel function and gating in a dominant manner. Cell Mol Life Sci 2015; 72:3387-99. [PMID: 25854634 PMCID: PMC4531139 DOI: 10.1007/s00018-015-1894-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Revised: 03/05/2015] [Accepted: 03/24/2015] [Indexed: 12/14/2022]
Abstract
The dominantly inherited cerebellar ataxias are a heterogeneous group of neurodegenerative disorders caused by Purkinje cell loss in the cerebellum. Recently, we identified loss-of-function mutations in the KCND3 gene as the cause of spinocerebellar ataxia type 19/22 (SCA19/22), revealing a previously unknown role for the voltage-gated potassium channel, Kv4.3, in Purkinje cell survival. However, how mutant Kv4.3 affects wild-type Kv4.3 channel functioning remains unknown. We provide evidence that SCA19/22-mutant Kv4.3 exerts a dominant negative effect on the trafficking and surface expression of wild-type Kv4.3 in the absence of its regulatory subunit, KChIP2. Notably, this dominant negative effect can be rescued by the presence of KChIP2. We also found that all SCA19/22-mutant subunits either suppress wild-type Kv4.3 current amplitude or alter channel gating in a dominant manner. Our findings suggest that altered Kv4.3 channel localization and/or functioning resulting from SCA19/22 mutations may lead to Purkinje cell loss, neurodegeneration and ataxia.
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Affiliation(s)
- Anna Duarri
- Department of Genetics, University of Groningen, University Medical Center Groningen, PO Box 30 001, 9700 RB, Groningen, The Netherlands
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11
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Duarri A, Nibbeling EAR, Fokkens MR, Meijer M, Boerrigter M, Verschuuren-Bemelmans CC, Kremer BPH, van de Warrenburg BP, Dooijes D, Boddeke E, Sinke RJ, Verbeek DS. Functional analysis helps to define KCNC3 mutational spectrum in Dutch ataxia cases. PLoS One 2015; 10:e0116599. [PMID: 25756792 PMCID: PMC4355074 DOI: 10.1371/journal.pone.0116599] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Accepted: 12/12/2014] [Indexed: 12/03/2022] Open
Abstract
Spinocerebellar ataxia type 13 (SCA13) is an autosomal dominantly inherited neurodegenerative disorder of the cerebellum caused by mutations in the voltage gated potassium channel KCNC3. To identify novel pathogenic SCA13 mutations in KCNC3 and to gain insights into the disease prevalence in the Netherlands, we sequenced the entire coding region of KCNC3 in 848 Dutch cerebellar ataxia patients with familial or sporadic origin. We evaluated the pathogenicity of the identified variants by co-segregation analysis and in silico prediction followed by biochemical and electrophysiological studies. We identified 19 variants in KCNC3 including 2 non-coding, 11 missense and 6 synonymous variants. Two missense variants did not co-segregate with the disease and were excluded as potentially disease-causing mutations. We also identified the previously reported p.R420H and p.R423H mutations in our cohort. Of the remaining 7 missense variants, functional analysis revealed that 2 missense variants shifted Kv3.3 channel activation to more negative voltages. These variations were associated with early disease onset and mild intellectual disability. Additionally, one other missense variant shifted channel activation to more positive voltages and was associated with spastic ataxic gait. Whereas, the remaining missense variants did not change any of the channel characteristics. Of these three functional variants, only one variant was in silico predicted to be damaging and segregated with disease. The other two variants were in silico predicted to be benign and co-segregation analysis was not optimal or could only be partially confirmed. Therefore, we conclude that we have identified at least one novel pathogenic mutation in KCNC3 that cause SCA13 and two additionally potential SCA13 mutations. This leads to an estimate of SCA13 prevalence in the Netherlands to be between 0.6% and 1.3%.
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Affiliation(s)
- Anna Duarri
- Department of Genetics, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Esther A. R. Nibbeling
- Department of Genetics, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Michiel R. Fokkens
- Department of Genetics, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Michel Meijer
- Department of Medical Physiology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Melissa Boerrigter
- Department of Genetics, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | | | - Berry P. H. Kremer
- Department of Neurology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | | | - Dennis Dooijes
- Department of Medical Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Erik Boddeke
- Department of Medical Physiology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Richard J. Sinke
- Department of Genetics, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Dineke S. Verbeek
- Department of Genetics, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
- * E-mail:
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