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Boycott KM, Rath A, Chong JX, Hartley T, Alkuraya FS, Baynam G, Brookes AJ, Brudno M, Carracedo A, den Dunnen JT, Dyke SOM, Estivill X, Goldblatt J, Gonthier C, Groft SC, Gut I, Hamosh A, Hieter P, Höhn S, Hurles ME, Kaufmann P, Knoppers BM, Krischer JP, Macek M, Matthijs G, Olry A, Parker S, Paschall J, Philippakis AA, Rehm HL, Robinson PN, Sham PC, Stefanov R, Taruscio D, Unni D, Vanstone MR, Zhang F, Brunner H, Bamshad MJ, Lochmüller H. International Cooperation to Enable the Diagnosis of All Rare Genetic Diseases. Am J Hum Genet 2017; 100:695-705. [PMID: 28475856 PMCID: PMC5420351 DOI: 10.1016/j.ajhg.2017.04.003] [Citation(s) in RCA: 245] [Impact Index Per Article: 35.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Provision of a molecularly confirmed diagnosis in a timely manner for children and adults with rare genetic diseases shortens their "diagnostic odyssey," improves disease management, and fosters genetic counseling with respect to recurrence risks while assuring reproductive choices. In a general clinical genetics setting, the current diagnostic rate is approximately 50%, but for those who do not receive a molecular diagnosis after the initial genetics evaluation, that rate is much lower. Diagnostic success for these more challenging affected individuals depends to a large extent on progress in the discovery of genes associated with, and mechanisms underlying, rare diseases. Thus, continued research is required for moving toward a more complete catalog of disease-related genes and variants. The International Rare Diseases Research Consortium (IRDiRC) was established in 2011 to bring together researchers and organizations invested in rare disease research to develop a means of achieving molecular diagnosis for all rare diseases. Here, we review the current and future bottlenecks to gene discovery and suggest strategies for enabling progress in this regard. Each successful discovery will define potential diagnostic, preventive, and therapeutic opportunities for the corresponding rare disease, enabling precision medicine for this patient population.
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Affiliation(s)
- Kym M Boycott
- Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, ON K1H 8L1, Canada.
| | - Ana Rath
- Orphanet, Institut National de la Santé et de la Recherche Médicale US14, 75014 Paris, France
| | - Jessica X Chong
- Department of Pediatrics, University of Washington, Seattle, WA 98195, USA
| | - Taila Hartley
- Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, ON K1H 8L1, Canada
| | - Fowzan S Alkuraya
- Department of Genetics, King Faisal Research Center, Riyadh 11211, Saudi Arabia; Saudi Human Genome Program, King Abdulaziz City for Science and Technology, Riyadh 11442, Saudi Arabia
| | - Gareth Baynam
- Genetic Services of Western Australia, Perth, WA 6008, Australia
| | - Anthony J Brookes
- Department of Genetics, University of Leicester, Leicester LE1 7RH, UK
| | - Michael Brudno
- Department of Computer Science, University of Toronto, Toronto M5S 1A1, Canada
| | - Angel Carracedo
- Genomic Medicine Group, Galician Foundation of Genomic Medicine and University of Santiago de Compostela, 15782 Santiago de Compostela, Spain
| | - Johan T den Dunnen
- Departments of Human Genetics and Clinical Genetics, Leiden University Medical Center, Albinusdreef 2, 2333 ZA Leiden, the Netherlands
| | - Stephanie O M Dyke
- Centre of Genomics and Policy, Department of Human Genetics, Faculty of Medicine, McGill University, Montreal, QC H3A 1A4, Canada
| | - Xavier Estivill
- Experimental Division, Sidra Medical and Research Center, PO Box 26999, Doha, Qatar; Genetics Unit, Dexeus Woman's Health, 08028 Barcelona, Spain
| | - Jack Goldblatt
- Genetic Services of Western Australia, Perth, WA 6008, Australia
| | - Catherine Gonthier
- Orphanet, Institut National de la Santé et de la Recherche Médicale US14, 75014 Paris, France
| | - Stephen C Groft
- National Center for Advancing Translational Sciences, National Institutes of Health, Bethesda, MD 20892-4874, USA
| | - Ivo Gut
- Centre Nacional d'Anàlisi Genòmica, Center for Genomic Regulation, Barcelona Institute of Science and Technology, Universitat Pompeu Fabra, 08028 Barcelona, Spain
| | - Ada Hamosh
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21286, USA
| | - Philip Hieter
- Michael Smith Laboratories, Department of Medical Genetics, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Sophie Höhn
- Orphanet, Institut National de la Santé et de la Recherche Médicale US14, 75014 Paris, France
| | - Matthew E Hurles
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton CB10 1SA, UK
| | - Petra Kaufmann
- Office of Rare Diseases Research, National Center for Advancing Translational Sciences, National Institutes of Health, Bethesda, MD 20892-4874, USA
| | - Bartha M Knoppers
- Centre of Genomics and Policy, Department of Human Genetics, Faculty of Medicine, McGill University, Montreal, QC H3A 1A4, Canada
| | - Jeffrey P Krischer
- University of South Florida Health Informatics Institute, Tampa, FL 33620, USA
| | - Milan Macek
- Department of Biology and Medical Genetics, Second Faculty of Medicine, Charles University and University Hospital Motol, 150 06 Prague 5, Czech Republic
| | - Gert Matthijs
- Center for Human Genetics, University of Leuven, 3000 Leuven, Belgium
| | - Annie Olry
- Orphanet, Institut National de la Santé et de la Recherche Médicale US14, 75014 Paris, France
| | | | - Justin Paschall
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton CB10 1SA, UK
| | | | - Heidi L Rehm
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Peter N Robinson
- Institut für Medizinische Genetik und Humangenetik, Charité Universitätsmdizin Berlin, 13353 Berlin, Germany; Jackson Laboratory for Genomic Medicine, Farmington, CT 06032, USA
| | - Pak-Chung Sham
- Centre for Genomic Sciences, University of Hong Kong, Hong Kong, China
| | - Rumen Stefanov
- Department of Social Medicine and Public Health, Faculty of Public Health, Medical University of Plovdiv, Plovdiv 4002, Bulgaria
| | - Domenica Taruscio
- National Centre for Rare Diseases, Istituto Superiore di Sanità, Rome 299-00161, Italy
| | - Divya Unni
- Orphanet, Institut National de la Santé et de la Recherche Médicale US14, 75014 Paris, France
| | - Megan R Vanstone
- Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, ON K1H 8L1, Canada
| | - Feng Zhang
- WuXi AppTec, Waigaoqiao Free Trade Zone, Shanghai 200131, China; WuXi NextCODE, Cambridge, MA 02142, USA
| | - Han Brunner
- Department of Human Genetics, Radboud University Medical Center, 6525 GA Nijmegen, the Netherlands; Maastricht University Medical Center, Department of Clinical Genetics, 6229 GT Maastricht, the Netherlands
| | - Michael J Bamshad
- Department of Pediatrics, University of Washington, Seattle, WA 98195, USA; Division of Genetic Medicine, Seattle Children's Hospital, Seattle, WA 98105, USA
| | - Hanns Lochmüller
- John Walton Muscular Dystrophy Research Centre, MRC Centre for Neuromuscular Diseases, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne NE1 3BZ, UK
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2
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Choquet K, Tétreault M, Yang S, La Piana R, Dicaire MJ, Vanstone MR, Mathieu J, Bouchard JP, Rioux MF, Rouleau GA, Boycott KM, Majewski J, Brais B. SPG7 mutations explain a significant proportion of French Canadian spastic ataxia cases. Eur J Hum Genet 2015; 24:1016-21. [PMID: 26626314 DOI: 10.1038/ejhg.2015.240] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Revised: 10/01/2015] [Accepted: 10/14/2015] [Indexed: 12/13/2022] Open
Abstract
Hereditary cerebellar ataxias and hereditary spastic paraplegias are clinically and genetically heterogeneous and often overlapping neurological disorders. Mutations in SPG7 cause the autosomal recessive spastic paraplegia type 7 (SPG7), but recent studies indicate that they are also one of the most common causes of recessive cerebellar ataxia. In Quebec, a significant number of patients affected with cerebellar ataxia and spasticity remain without a molecular diagnosis. We performed whole-exome sequencing in three French Canadian (FC) patients affected with spastic ataxia and uncovered compound heterozygous variants in SPG7 in all three. Sanger sequencing of SPG7 exons and exon/intron boundaries was used to screen additional patients. In total, we identified recessive variants in SPG7 in 22 FC patients belonging to 12 families (38.7% of the families screened), including two novel variants. The p.(Ala510Val) variant was the most common in our cohort. Cerebellar features, including ataxia, were more pronounced than spasticity in this cohort. These results strongly suggest that variants affecting the function of SPG7 are the fourth most common form of recessive ataxia in FC patients. Thus, we propose that SPG7 mutations explain a significant proportion of FC spastic ataxia cases and that this gene should be considered in unresolved patients.
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Affiliation(s)
- Karine Choquet
- Neurogenetics of Motion Laboratory, Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Québec, Canada.,Department of Human Genetics, Montreal Neurological Institute, McGill University, Montreal, Québec, Canada
| | - Martine Tétreault
- Department of Human Genetics, Montreal Neurological Institute, McGill University, Montreal, Québec, Canada.,McGill University and Genome Quebec Innovation Center, Montreal, Québec, Canada
| | - Sharon Yang
- Neurogenetics of Motion Laboratory, Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Québec, Canada
| | - Roberta La Piana
- Neurogenetics of Motion Laboratory, Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Québec, Canada
| | - Marie-Josée Dicaire
- Neurogenetics of Motion Laboratory, Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Québec, Canada
| | - Megan R Vanstone
- Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, Ontario, Canada
| | - Jean Mathieu
- Complexe Hospitalier de la Sagamie et Faculté de Médecine et des Sciences de la Santé de l'Université de Sherbrooke, Jonquière, Québec, Canada
| | - Jean-Pierre Bouchard
- Hôpital Enfant-Jésus, CHU de Québec et Département des Sciences Neurologiques, Faculté de Médecine de l'Université Laval, Québec, Québec, Canada
| | - Marie-France Rioux
- Centre Hospitalier Universitaire de Sherbrooke - Hôpital Fleurimont, Sherbrooke, Québec, Canada
| | - Guy A Rouleau
- Montreal Neurological Institute and Hospital and Department of Neurology and Neurosurgery, McGill University, Montreal, Québec, Canada
| | | | - Kym M Boycott
- Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, Ontario, Canada
| | - Jacek Majewski
- Department of Human Genetics, Montreal Neurological Institute, McGill University, Montreal, Québec, Canada.,McGill University and Genome Quebec Innovation Center, Montreal, Québec, Canada
| | - Bernard Brais
- Neurogenetics of Motion Laboratory, Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Québec, Canada.,Department of Human Genetics, Montreal Neurological Institute, McGill University, Montreal, Québec, Canada
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3
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Huang L, Vanstone MR, Hartley T, Osmond M, Barrowman N, Allanson J, Baker L, Dabir TA, Dipple KM, Dobyns WB, Estrella J, Faghfoury H, Favaro FP, Goel H, Gregersen PA, Gripp KW, Grix A, Guion-Almeida ML, Harr MH, Hudson C, Hunter AGW, Johnson J, Joss SK, Kimball A, Kini U, Kline AD, Lauzon J, Lildballe DL, López-González V, Martinezmoles J, Meldrum C, Mirzaa GM, Morel CF, Morton JEV, Pyle LC, Quintero-Rivera F, Richer J, Scheuerle AE, Schönewolf-Greulich B, Shears DJ, Silver J, Smith AC, Temple IK, van de Kamp JM, van Dijk FS, Vandersteen AM, White SM, Zackai EH, Zou R, Bulman DE, Boycott KM, Lines MA. Mandibulofacial Dysostosis with Microcephaly: Mutation and Database Update. Hum Mutat 2015; 37:148-54. [PMID: 26507355 DOI: 10.1002/humu.22924] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [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: 07/08/2015] [Accepted: 10/12/2015] [Indexed: 11/08/2022]
Abstract
Mandibulofacial dysostosis with microcephaly (MFDM) is a multiple malformation syndrome comprising microcephaly, craniofacial anomalies, hearing loss, dysmorphic features, and, in some cases, esophageal atresia. Haploinsufficiency of a spliceosomal GTPase, U5-116 kDa/EFTUD2, is responsible. Here, we review the molecular basis of MFDM in the 69 individuals described to date, and report mutations in 38 new individuals, bringing the total number of reported individuals to 107 individuals from 94 kindreds. Pathogenic EFTUD2 variants comprise 76 distinct mutations and seven microdeletions. Among point mutations, missense substitutions are infrequent (14 out of 76; 18%) relative to stop-gain (29 out of 76; 38%), and splicing (33 out of 76; 43%) mutations. Where known, mutation origin was de novo in 48 out of 64 individuals (75%), dominantly inherited in 12 out of 64 (19%), and due to proven germline mosaicism in four out of 64 (6%). Highly penetrant clinical features include, microcephaly, first and second arch craniofacial malformations, and hearing loss; esophageal atresia is present in an estimated ∼27%. Microcephaly is virtually universal in childhood, with some adults exhibiting late "catch-up" growth and normocephaly at maturity. Occasionally reported anomalies, include vestibular and ossicular malformations, reduced mouth opening, atrophy of cerebral white matter, structural brain malformations, and epibulbar dermoid. All reported EFTUD2 mutations can be found in the EFTUD2 mutation database (http://databases.lovd.nl/shared/genes/EFTUD2).
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Affiliation(s)
- Lijia Huang
- The Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, Ontario, Canada
| | - Megan R Vanstone
- The Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, Ontario, Canada
| | - Taila Hartley
- The Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, Ontario, Canada
| | - Matthew Osmond
- The Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, Ontario, Canada
| | - Nick Barrowman
- The Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, Ontario, Canada.,Department of Pediatrics, University of Ottawa, Ottawa, Ontario, Canada
| | - Judith Allanson
- Department of Pediatrics, University of Ottawa, Ottawa, Ontario, Canada.,Department of Genetics, The Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada
| | - Laura Baker
- Division of Medical Genetics, A. I. duPont Hospital for Children, Wilmington, Delaware
| | - Tabib A Dabir
- Clinical Genetics Department, Belfast City Hospital, Belfast, UK
| | - Katrina M Dipple
- Department of Pediatrics and Human Genetics, David Geffen School of Medicine, University of California, Los Angeles, California
| | - William B Dobyns
- Division of Genetic Medicine, Department of Pediatrics, University of Washington, Seattle, Washington.,Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington
| | - Jane Estrella
- Department of Medical Genetics, Westmead Hospital, Sydney, Australia
| | - Hanna Faghfoury
- The Fred A. Litwin Family Centre in Genetic Medicine, University Health Network and Mount Sinai Hospital, University of Toronto, Toronto, Ontario, Canada
| | - Francine P Favaro
- Department of Clinical Genetics, Hospital for Rehabilitation of Craniofacial Anomalies, University of São Paulo, Bauru, Brazil
| | - Himanshu Goel
- Hunter Genetics, Newcastle, Waratah, Australia.,University of Newcastle, Newcastle - School of Medicine and Public Health, Faculty of Health, Callaghan, Australia
| | | | - Karen W Gripp
- Division of Medical Genetics, A. I. duPont Hospital for Children, Wilmington, Delaware
| | - Art Grix
- Department of Genetics, Permanente Medical Group, Roseville, California
| | - Maria-Leine Guion-Almeida
- Department of Clinical Genetics, Hospital for Rehabilitation of Craniofacial Anomalies, University of São Paulo, Bauru, Brazil
| | - Margaret H Harr
- Division of Human Genetics, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania.,The Perelman School of Medicine of the University of Pennsylvania, Philadelphia, Pennsylvania
| | | | | | - John Johnson
- Shodair Children's Hospital, Helena, Montana.,Clinical Genetics and Metabolism, Floating Hospital for Children, Tufts Medical Center, Boston, Massachusetts
| | - Shelagh K Joss
- West of Scotland Clinical Genetics Service, South Glasgow University Hospital, Glasgow, UK
| | - Amy Kimball
- Harvey Institute for Human Genetics, Greater Baltimore Medical Center, Baltimore, Maryland
| | - Usha Kini
- Department of Clinical Genetics, Oxford University Hospitals NHS Trust, Oxford, UK
| | - Antonie D Kline
- Harvey Institute for Human Genetics, Greater Baltimore Medical Center, Baltimore, Maryland
| | - Julie Lauzon
- Department of Medical Genetics, Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
| | - Dorte L Lildballe
- Department of Clinical Genetics, Aarhus University Hospital, Aarhus, Denmark
| | - Vanesa López-González
- Sección de Genética Médica, Servicio de Pediatría, Hospital Clínico Universitario Virgen de la Arrixaca, IMIB-Arrixaca, Murcia, Spain.,Grupo Clínico Vinculado al Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III (ISCIII), Madrid, Spain
| | | | | | - Ghayda M Mirzaa
- Division of Genetic Medicine, Department of Pediatrics, University of Washington, Seattle, Washington.,Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington
| | - Chantal F Morel
- The Fred A. Litwin Family Centre in Genetic Medicine, University Health Network and Mount Sinai Hospital, University of Toronto, Toronto, Ontario, Canada
| | - Jenny E V Morton
- West Midlands Regional Genetics Service, Birmingham Women's Hospital, Birmingham, UK
| | - Louise C Pyle
- Department of Pediatrics, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania
| | - Fabiola Quintero-Rivera
- Department of Pathology and Laboratory Medicine, UCLA Clinical Genomics Center, David Geffen School of Medicine, University of California, Los Angeles, California
| | - Julie Richer
- The Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, Ontario, Canada.,Department of Genetics, The Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada
| | - Angela E Scheuerle
- Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Bitten Schönewolf-Greulich
- Genetic Counselling Clinic Kennedy Center, Copenhagen University Hospital, Rigshospitalet, Glostrup, Denmark
| | - Deborah J Shears
- Oxford Regional Genetics Service, The Churchill Hospital, Oxford University Hospitals NHS Trust, Oxford, UK
| | - Josh Silver
- The Fred A. Litwin Family Centre in Genetic Medicine, University Health Network and Mount Sinai Hospital, University of Toronto, Toronto, Ontario, Canada
| | - Amanda C Smith
- Department of Genetics, The Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada
| | - I Karen Temple
- Human Development and Health, Faculty of Medicine, University of Southampton, Southampton, UK.,Wessex Clinical Genetics Service, Princess Anne Hospital, University Hospital Southampton NHS Foundation Trust, Southampton, UK
| | | | | | - Fleur S van Dijk
- Department of Clinical Genetics, VU Medical Center, Amsterdam, The Netherlands
| | | | - Sue M White
- Victoria Clinical Genetics Service, Murdoch Children's Research Institute, Melbourne, Australia.,Department of Paediatrics, University of Melbourne, Melbourne, Australia
| | - Elaine H Zackai
- Division of Human Genetics, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania.,Department of Pediatrics, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania
| | - Ruobing Zou
- The Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, Ontario, Canada
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- The Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, Ontario, Canada
| | - Dennis E Bulman
- The Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, Ontario, Canada.,Newborn Screening Ontario, The Children's Hospital of Eastern Ontario, Ottawa, Canada
| | - Kym M Boycott
- The Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, Ontario, Canada.,Department of Genetics, The Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada
| | - Matthew A Lines
- The Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, Ontario, Canada.,Department of Pediatrics, University of Ottawa, Ottawa, Ontario, Canada.,Metabolics and Newborn Screening, Department of Pediatrics, The Children's Hospital of Eastern Ontario, Ottawa, Canada
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Affiliation(s)
- Kym M. Boycott
- Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, Ontario, K1H 8L1 Canada; , , , , ,
| | - David A. Dyment
- Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, Ontario, K1H 8L1 Canada; , , , , ,
| | - Sarah L. Sawyer
- Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, Ontario, K1H 8L1 Canada; , , , , ,
| | - Megan R. Vanstone
- Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, Ontario, K1H 8L1 Canada; , , , , ,
| | - Chandree L. Beaulieu
- Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, Ontario, K1H 8L1 Canada; , , , , ,
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5
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Dyment DA, Sell E, Vanstone MR, Smith AC, Garandeau D, Garcia V, Carpentier S, Le Trionnaire E, Sabourdy F, Beaulieu CL, Schwartzentruber JA, McMillan HJ, Majewski J, Bulman DE, Levade T, Boycott KM. Evidence for clinical, genetic and biochemical variability in spinal muscular atrophy with progressive myoclonic epilepsy. Clin Genet 2013; 86:558-63. [PMID: 24164096 DOI: 10.1111/cge.12307] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2013] [Revised: 10/08/2013] [Accepted: 10/22/2013] [Indexed: 10/26/2022]
Abstract
Spinal muscular atrophy with progressive myoclonic epilepsy (SMA-PME) is a recently delineated, autosomal recessive condition caused by rare mutations in the N-acylsphingosine amidohydrolase 1 (acid ceramidase) ASAH1 gene. It is characterized by motor neuron disease followed by progressive myoclonic seizures and eventual death due to respiratory insufficiency. Here we report an adolescent female who presented with atonic and absence seizures and myoclonic jerks and was later diagnosed as having myoclonic-absence seizures. An extensive genetic and metabolic work-up was unable to arrive at a molecular diagnosis. Whole exome sequencing (WES) identified two rare, deleterious mutations in the ASAH1 gene: c.850G>T;p.Gly284X and c.456A>C;p.Lys152Asn. These mutations were confirmed by Sanger sequencing in the patient and her parents. Functional studies in cultured fibroblasts showed that acid ceramidase was reduced in both overall amount and enzymatic activity. Ceramide level was doubled in the patient's fibroblasts as compared to control cells. The results of the WES and the functional studies prompted an electromyography (EMG) study that showed evidence of motor neuron disease despite only mild proximal muscle weakness. These findings expand the phenotypic spectrum of SMA-PME caused by novel mutations in ASAH1 and highlight the clinical utility of WES for rare, intractable forms of epilepsy.
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Affiliation(s)
- D A Dyment
- Department of Genetics, Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada; Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, Ontario, Canada
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6
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Boycott KM, Vanstone MR, Bulman DE, MacKenzie AE. Rare-disease genetics in the era of next-generation sequencing: discovery to translation. Nat Rev Genet 2013; 14:681-91. [PMID: 23999272 DOI: 10.1038/nrg3555] [Citation(s) in RCA: 502] [Impact Index Per Article: 45.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Work over the past 25 years has resulted in the identification of genes responsible for ~50% of the estimated 7,000 rare monogenic diseases, and it is predicted that most of the remaining disease-causing genes will be identified by the year 2020, and probably sooner. This marked acceleration is the result of dramatic improvements in DNA-sequencing technologies and the associated analyses. We examine the rapid maturation of rare-disease genetic analysis and successful strategies for gene identification. We highlight the impact of discovering rare-disease-causing genes, from clinical diagnostics to insights gained into biological mechanisms and common diseases. Last, we explore the increasing therapeutic opportunities and challenges that the resulting expansion of the 'atlas' of human genetic pathology will bring.
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Affiliation(s)
- Kym M Boycott
- Department of Pediatrics, University of Ottawa and Children's Hospital of Eastern Ontario Research Institute, 401 Smyth Road, Ottawa, Ontario K1H 8L1, Canada
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