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Pagnamenta AT, Yu J, Walker S, Noble AJ, Lord J, Dutta P, Hashim M, Camps C, Green H, Devaiah S, Nashef L, Parr J, Fratter C, Ibnouf Hussein R, Lindsay SJ, Lalloo F, Banos-Pinero B, Evans D, Mallin L, Waite A, Evans J, Newman A, Allen Z, Perez-Becerril C, Ryan G, Hart R, Taylor J, Bedenham T, Clement E, Blair E, Hay E, Forzano F, Higgs J, Canham N, Majumdar A, McEntagart M, Lahiri N, Stewart H, Smithson S, Calpena E, Jackson A, Banka S, Titheradge H, McGowan R, Rankin J, Shaw-Smith C, Evans DG, Burghel GJ, Smith MJ, Anderson E, Madhu R, Firth H, Ellard S, Brennan P, Anderson C, Taupin D, Rogers MT, Cook JA, Durkie M, East JE, Fowler D, Wilson L, Igbokwe R, Gardham A, Tomlinson I, Baralle D, Uhlig HH, Taylor JC. The impact of inversions across 33,924 families with rare disease from a national genome sequencing project. Am J Hum Genet 2024; 111:1140-1164. [PMID: 38776926 PMCID: PMC11179413 DOI: 10.1016/j.ajhg.2024.04.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2023] [Revised: 04/25/2024] [Accepted: 04/25/2024] [Indexed: 05/25/2024] Open
Abstract
Detection of structural variants (SVs) is currently biased toward those that alter copy number. The relative contribution of inversions toward genetic disease is unclear. In this study, we analyzed genome sequencing data for 33,924 families with rare disease from the 100,000 Genomes Project. From a database hosting >500 million SVs, we focused on 351 genes where haploinsufficiency is a confirmed disease mechanism and identified 47 ultra-rare rearrangements that included an inversion (24 bp to 36.4 Mb, 20/47 de novo). Validation utilized a number of orthogonal approaches, including retrospective exome analysis. RNA-seq data supported the respective diagnoses for six participants. Phenotypic blending was apparent in four probands. Diagnostic odysseys were a common theme (>50 years for one individual), and targeted analysis for the specific gene had already been performed for 30% of these individuals but with no findings. We provide formal confirmation of a European founder origin for an intragenic MSH2 inversion. For two individuals with complex SVs involving the MECP2 mutational hotspot, ambiguous SV structures were resolved using long-read sequencing, influencing clinical interpretation. A de novo inversion of HOXD11-13 was uncovered in a family with Kantaputra-type mesomelic dysplasia. Lastly, a complex translocation disrupting APC and involving nine rearranged segments confirmed a clinical diagnosis for three family members and resolved a conundrum for a sibling with a single polyp. Overall, inversions play a small but notable role in rare disease, likely explaining the etiology in around 1/750 families across heterogeneous clinical cohorts.
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Affiliation(s)
- Alistair T Pagnamenta
- Oxford Biomedical Research Centre, Centre for Human Genetics, University of Oxford, Oxford, UK.
| | - Jing Yu
- Oxford Biomedical Research Centre, Centre for Human Genetics, University of Oxford, Oxford, UK; Novo Nordisk Oxford Research Centre, Oxford, UK
| | | | - Alexandra J Noble
- Translational Gastroenterology Unit, John Radcliffe Hospital, Oxford, UK
| | - Jenny Lord
- School of Human Development and Health, Faculty of Medicine, University of Southampton, Southampton, UK; Sheffield Institute for Translational Neuroscience, The University of Sheffield, Sheffield, UK
| | - Prasun Dutta
- Oxford Biomedical Research Centre, Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Mona Hashim
- Oxford Biomedical Research Centre, Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Carme Camps
- Oxford Biomedical Research Centre, Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Hannah Green
- Oxford Genetics Laboratories, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Smrithi Devaiah
- Oxford Centre for Genomic Medicine, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Lina Nashef
- Department of Neurology, King's College Hospital, London, UK
| | - Jason Parr
- Manchester Centre for Genomic Medicine, Manchester University Hospitals NHS Foundation Trust, Health Innovation Manchester, Manchester, UK
| | - Carl Fratter
- Oxford Genetics Laboratories, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Rana Ibnouf Hussein
- Manchester Centre for Genomic Medicine, Manchester University Hospitals NHS Foundation Trust, Health Innovation Manchester, Manchester, UK
| | - Sarah J Lindsay
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, UK
| | - Fiona Lalloo
- Manchester Centre for Genomic Medicine, Manchester University Hospitals NHS Foundation Trust, Health Innovation Manchester, Manchester, UK
| | - Benito Banos-Pinero
- Oxford Genetics Laboratories, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - David Evans
- Exeter Genomics Laboratory, Royal Devon University Healthcare NHS Foundation Trust, Exeter, UK
| | - Lucy Mallin
- Exeter Genomics Laboratory, Royal Devon University Healthcare NHS Foundation Trust, Exeter, UK
| | - Adrian Waite
- Bristol Genetics Laboratory, North Bristol NHS Trust, Bristol, UK
| | - Julie Evans
- Bristol Genetics Laboratory, North Bristol NHS Trust, Bristol, UK
| | - Andrew Newman
- The All Wales Medical Genomics Service, University Hospital of Wales, Cardiff, UK
| | - Zoe Allen
- North Thames Rare and Inherited Disease Laboratory, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Cristina Perez-Becerril
- Manchester Centre for Genomic Medicine, Manchester University Hospitals NHS Foundation Trust, Health Innovation Manchester, Manchester, UK
| | - Gavin Ryan
- West Midlands Regional Genetics Laboratory, Central and South Genomic Laboratory Hub, Birmingham, UK
| | - Rachel Hart
- Liverpool Centre for Genomic Medicine, Liverpool Women's NHS Foundation Trust, Liverpool, UK
| | - John Taylor
- Oxford Genetics Laboratories, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Tina Bedenham
- Oxford Genetics Laboratories, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Emma Clement
- North East Thames Regional Genetic Service, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Ed Blair
- Oxford Centre for Genomic Medicine, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Eleanor Hay
- North East Thames Regional Genetic Service, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Francesca Forzano
- Clinical Genetics Department, Guy's and St Thomas' NHS Foundation Trust, London, UK
| | - Jenny Higgs
- Liverpool Centre for Genomic Medicine, Liverpool Women's NHS Foundation Trust, Liverpool, UK
| | - Natalie Canham
- Liverpool Centre for Genomic Medicine, Liverpool Women's NHS Foundation Trust, Liverpool, UK
| | - Anirban Majumdar
- Department of Paediatric Neurology, Bristol Children's Hospital, Bristol, UK
| | - Meriel McEntagart
- SW Thames Centre for Genomic Medicine, University of London & St George's University Hospitals NHS Foundation Trust, St George's, London, UK
| | - Nayana Lahiri
- SW Thames Centre for Genomic Medicine, University of London & St George's University Hospitals NHS Foundation Trust, St George's, London, UK
| | - Helen Stewart
- Oxford Centre for Genomic Medicine, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Sarah Smithson
- Department of Clinical Genetics, University Hospitals Bristol NHS Foundation Trust, Bristol, UK
| | - Eduardo Calpena
- Clinical Genetics Group, MRC Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK; Grupo de Investigación en Biomedicina Molecular, Celular y Genómica, Unidad CIBERER (CB06/07/1030), Instituto de Investigación Sanitaria La Fe (IIS La Fe), Valencia, Spain
| | - Adam Jackson
- Manchester Centre for Genomic Medicine, Manchester University Hospitals NHS Foundation Trust, Health Innovation Manchester, Manchester, UK; Division of Evolution, Infection and Genomics, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - Siddharth Banka
- Manchester Centre for Genomic Medicine, Manchester University Hospitals NHS Foundation Trust, Health Innovation Manchester, Manchester, UK; Division of Evolution, Infection and Genomics, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - Hannah Titheradge
- Department of Clinical Genetics, Birmingham Women's and Children's NHS Foundation Trust, Birmingham, UK
| | - Ruth McGowan
- West of Scotland Centre for Genomic Medicine, Glasgow, UK
| | - Julia Rankin
- Department of Clinical Genetics, Royal Devon University Healthcare NHS Trust, Exeter, UK
| | - Charles Shaw-Smith
- Department of Clinical Genetics, Royal Devon University Healthcare NHS Trust, Exeter, UK
| | - D Gareth Evans
- Manchester Centre for Genomic Medicine, Manchester University Hospitals NHS Foundation Trust, Health Innovation Manchester, Manchester, UK; Division of Evolution, Infection and Genomics, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - George J Burghel
- Manchester Centre for Genomic Medicine, Manchester University Hospitals NHS Foundation Trust, Health Innovation Manchester, Manchester, UK
| | - Miriam J Smith
- Manchester Centre for Genomic Medicine, Manchester University Hospitals NHS Foundation Trust, Health Innovation Manchester, Manchester, UK
| | - Emily Anderson
- Liverpool Centre for Genomic Medicine, Liverpool Women's NHS Foundation Trust, Liverpool, UK
| | - Rajesh Madhu
- Paediatric Neurosciences Department, Alder Hey Children's Hospital NHS Foundation Trust, Liverpool, UK
| | - Helen Firth
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, UK
| | - Sian Ellard
- Exeter Genomics Laboratory, Royal Devon University Healthcare NHS Foundation Trust, Exeter, UK
| | - Paul Brennan
- Institute of Genetic Medicine, Newcastle University, International Centre for Life, Newcastle University, Newcastle, UK
| | - Claire Anderson
- Canberra Clinical Genomics, Canberra Health Services and The Australian National University, Canberra, ACT, Australia
| | - Doug Taupin
- Cancer Research, Canberra Hospital, Canberra, ACT, Australia
| | - Mark T Rogers
- The All Wales Medical Genomics Service, University Hospital of Wales, Cardiff, UK
| | - Jackie A Cook
- Department of Clinical Genetics, Sheffield Children's NHS Foundation Trust, Sheffield, UK
| | - Miranda Durkie
- Sheffield Diagnostic Genetics Service, Sheffield Children's NHS Foundation Trust, North East and Yorkshire Genomic Laboratory Hub, Sheffield, UK
| | - James E East
- Translational Gastroenterology Unit, John Radcliffe Hospital, Oxford, UK
| | - Darren Fowler
- Department of Cellular Pathology, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Louise Wilson
- North East Thames Regional Genetic Service, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Rebecca Igbokwe
- Department of Clinical Genetics, Birmingham Women's and Children's NHS Foundation Trust, Birmingham, UK
| | - Alice Gardham
- North East Thames Regional Genetic Service, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Ian Tomlinson
- Department of Oncology, University of Oxford, Oxford, UK
| | - Diana Baralle
- School of Human Development and Health, Faculty of Medicine, University of Southampton, Southampton, UK
| | - Holm H Uhlig
- Oxford Biomedical Research Centre, Centre for Human Genetics, University of Oxford, Oxford, UK; Translational Gastroenterology Unit, John Radcliffe Hospital, Oxford, UK
| | - Jenny C Taylor
- Oxford Biomedical Research Centre, Centre for Human Genetics, University of Oxford, Oxford, UK.
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Khalili Alashti S, Fallahi J, Mohammadi S, Dehghanian F, Farbood Z, Masoudi M, Poorang S, Jokar A, Fardaei M. Two novel mutations in the MECP2 gene in patients with Rett syndrome. Gene 2020; 732:144337. [DOI: 10.1016/j.gene.2020.144337] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Revised: 12/04/2019] [Accepted: 01/06/2020] [Indexed: 12/28/2022]
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Redin C, Gérard B, Lauer J, Herenger Y, Muller J, Quartier A, Masurel-Paulet A, Willems M, Lesca G, El-Chehadeh S, Le Gras S, Vicaire S, Philipps M, Dumas M, Geoffroy V, Feger C, Haumesser N, Alembik Y, Barth M, Bonneau D, Colin E, Dollfus H, Doray B, Delrue MA, Drouin-Garraud V, Flori E, Fradin M, Francannet C, Goldenberg A, Lumbroso S, Mathieu-Dramard M, Martin-Coignard D, Lacombe D, Morin G, Polge A, Sukno S, Thauvin-Robinet C, Thevenon J, Doco-Fenzy M, Genevieve D, Sarda P, Edery P, Isidor B, Jost B, Olivier-Faivre L, Mandel JL, Piton A. Efficient strategy for the molecular diagnosis of intellectual disability using targeted high-throughput sequencing. J Med Genet 2014; 51:724-36. [PMID: 25167861 PMCID: PMC4215287 DOI: 10.1136/jmedgenet-2014-102554] [Citation(s) in RCA: 197] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Background Intellectual disability (ID) is characterised by an extreme genetic heterogeneity. Several hundred genes have been associated to monogenic forms of ID, considerably complicating molecular diagnostics. Trio-exome sequencing was recently proposed as a diagnostic approach, yet remains costly for a general implementation. Methods We report the alternative strategy of targeted high-throughput sequencing of 217 genes in which mutations had been reported in patients with ID or autism as the major clinical concern. We analysed 106 patients with ID of unknown aetiology following array-CGH analysis and other genetic investigations. Ninety per cent of these patients were males, and 75% sporadic cases. Results We identified 26 causative mutations: 16 in X-linked genes (ATRX, CUL4B, DMD, FMR1, HCFC1, IL1RAPL1, IQSEC2, KDM5C, MAOA, MECP2, SLC9A6, SLC16A2, PHF8) and 10 de novo in autosomal-dominant genes (DYRK1A, GRIN1, MED13L, TCF4, RAI1, SHANK3, SLC2A1, SYNGAP1). We also detected four possibly causative mutations (eg, in NLGN3) requiring further investigations. We present detailed reasoning for assigning causality for each mutation, and associated patients’ clinical information. Some genes were hit more than once in our cohort, suggesting they correspond to more frequent ID-associated conditions (KDM5C, MECP2, DYRK1A, TCF4). We highlight some unexpected genotype to phenotype correlations, with causative mutations being identified in genes associated to defined syndromes in patients deviating from the classic phenotype (DMD, TCF4, MECP2). We also bring additional supportive (HCFC1, MED13L) or unsupportive (SHROOM4, SRPX2) evidences for the implication of previous candidate genes or mutations in cognitive disorders. Conclusions With a diagnostic yield of 25% targeted sequencing appears relevant as a first intention test for the diagnosis of ID, but importantly will also contribute to a better understanding regarding the specific contribution of the many genes implicated in ID and autism.
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Affiliation(s)
- Claire Redin
- Département de Médicine translationnelle et Neurogénétique, IGBMC, CNRS UMR 7104/INSERM U964/Université de Strasbourg, Illkirch, France Chaire de Génétique Humaine, Collège de France, Illkirch, France
| | - Bénédicte Gérard
- Laboratoire de diagnostic génétique, Hôpitaux Universitaires de Strasbourg, Strasbourg, France
| | - Julia Lauer
- Laboratoire de diagnostic génétique, Hôpitaux Universitaires de Strasbourg, Strasbourg, France
| | - Yvan Herenger
- Laboratoire de diagnostic génétique, Hôpitaux Universitaires de Strasbourg, Strasbourg, France
| | - Jean Muller
- Département de Médicine translationnelle et Neurogénétique, IGBMC, CNRS UMR 7104/INSERM U964/Université de Strasbourg, Illkirch, France Laboratoire de diagnostic génétique, Hôpitaux Universitaires de Strasbourg, Strasbourg, France
| | - Angélique Quartier
- Département de Médicine translationnelle et Neurogénétique, IGBMC, CNRS UMR 7104/INSERM U964/Université de Strasbourg, Illkirch, France Chaire de Génétique Humaine, Collège de France, Illkirch, France
| | - Alice Masurel-Paulet
- Centre de Génétique et Centre de Référence Anomalies du développement et Syndromes malformatifs, Hôpital d'Enfants, CHU de Dijon, Dijon, France
| | - Marjolaine Willems
- Département de Génétique Médicale, Centre de Référence Maladies Rares Anomalies du Développement et Syndromes Malformatifs Sud-Languedoc Roussillon, Hôpital Arnaud de Villeneuve, Montpellier, France
| | - Gaétan Lesca
- Département de Génétique Médicale, Hospices Civils de Lyon, Bron, France
| | - Salima El-Chehadeh
- Centre de Génétique et Centre de Référence Anomalies du développement et Syndromes malformatifs, Hôpital d'Enfants, CHU de Dijon, Dijon, France
| | - Stéphanie Le Gras
- Plateforme de Biopuces et Séquençage, IGBMC, CNRS UMR 7104/INSERM U964/Université de Strasbourg, Illkirch, France
| | - Serge Vicaire
- Plateforme de Biopuces et Séquençage, IGBMC, CNRS UMR 7104/INSERM U964/Université de Strasbourg, Illkirch, France
| | - Muriel Philipps
- Plateforme de Biopuces et Séquençage, IGBMC, CNRS UMR 7104/INSERM U964/Université de Strasbourg, Illkirch, France
| | - Michaël Dumas
- Plateforme de Biopuces et Séquençage, IGBMC, CNRS UMR 7104/INSERM U964/Université de Strasbourg, Illkirch, France
| | - Véronique Geoffroy
- Plateforme de Bioinformatique de Strasbourg (BIPS), IGBMC, CNRS UMR 7104/INSERM U964/Université de Strasbourg, Illkirch, France
| | - Claire Feger
- Plateforme de Biopuces et Séquençage, IGBMC, CNRS UMR 7104/INSERM U964/Université de Strasbourg, Illkirch, France
| | - Nicolas Haumesser
- Département de Médicine translationnelle et Neurogénétique, IGBMC, CNRS UMR 7104/INSERM U964/Université de Strasbourg, Illkirch, France Chaire de Génétique Humaine, Collège de France, Illkirch, France
| | - Yves Alembik
- Département de Génétique, CHU de Hautepierre, Strasbourg, France
| | - Magalie Barth
- Départment de Biochimie et de Génétique, CHU d'Angers, Angers, France
| | - Dominique Bonneau
- Départment de Biochimie et de Génétique, CHU d'Angers, Angers, France
| | - Estelle Colin
- Départment de Biochimie et de Génétique, CHU d'Angers, Angers, France
| | - Hélène Dollfus
- Laboratoire de Génétique Médicale, INSERM U1112, Faculté de Médecine de Strasbourg, Hôpitaux Universitaires de Strasbourg, Strasbourg, France
| | - Bérénice Doray
- Département de Génétique, CHU de Hautepierre, Strasbourg, France
| | - Marie-Ange Delrue
- CHU de Bordeaux, Génétique Médicale, Université de Bordeaux, Laboratoire MRGM, Bordeaux, France
| | | | - Elisabeth Flori
- Département de Génétique, CHU de Hautepierre, Strasbourg, France
| | - Mélanie Fradin
- Service de Génétique Médicale, Centre De Référence Anomalies du Développement, CHU de Rennes, Rennes, France
| | | | | | | | | | | | - Didier Lacombe
- CHU de Bordeaux, Génétique Médicale, Université de Bordeaux, Laboratoire MRGM, Bordeaux, France
| | - Gilles Morin
- Unité de Génétique Clinique, CHU d'Amiens, Amiens, France
| | - Anne Polge
- Laboratoire de Biochimie, CHU de Nîmes, Nîmes, France
| | - Sylvie Sukno
- Service de Neuropédiatrie, Hôpital Saint Vincent de Paul, Groupe Hospitalier de l'Institut Catholique Lillois, Faculté Libre de Médecine, Lille, France
| | - Christel Thauvin-Robinet
- Centre de Génétique et Centre de Référence Anomalies du développement et Syndromes malformatifs, Hôpital d'Enfants, CHU de Dijon, Dijon, France
| | - Julien Thevenon
- Centre de Génétique et Centre de Référence Anomalies du développement et Syndromes malformatifs, Hôpital d'Enfants, CHU de Dijon, Dijon, France
| | | | - David Genevieve
- Département de Génétique Médicale, Centre de Référence Maladies Rares Anomalies du Développement et Syndromes Malformatifs Sud-Languedoc Roussillon, Hôpital Arnaud de Villeneuve, Montpellier, France
| | - Pierre Sarda
- Département de Génétique Médicale, Centre de Référence Maladies Rares Anomalies du Développement et Syndromes Malformatifs Sud-Languedoc Roussillon, Hôpital Arnaud de Villeneuve, Montpellier, France
| | - Patrick Edery
- Département de Génétique Médicale, Hospices Civils de Lyon, Bron, France
| | - Bertrand Isidor
- Service de Génétique Médicale, CHU de Nantes, Nantes, France
| | - Bernard Jost
- Plateforme de Biopuces et Séquençage, IGBMC, CNRS UMR 7104/INSERM U964/Université de Strasbourg, Illkirch, France
| | - Laurence Olivier-Faivre
- Centre de Génétique et Centre de Référence Anomalies du développement et Syndromes malformatifs, Hôpital d'Enfants, CHU de Dijon, Dijon, France
| | - Jean-Louis Mandel
- Département de Médicine translationnelle et Neurogénétique, IGBMC, CNRS UMR 7104/INSERM U964/Université de Strasbourg, Illkirch, France Chaire de Génétique Humaine, Collège de France, Illkirch, France Laboratoire de diagnostic génétique, Hôpitaux Universitaires de Strasbourg, Strasbourg, France
| | - Amélie Piton
- Département de Médicine translationnelle et Neurogénétique, IGBMC, CNRS UMR 7104/INSERM U964/Université de Strasbourg, Illkirch, France Chaire de Génétique Humaine, Collège de France, Illkirch, France
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Hardwick SA, Reuter K, Williamson SL, Vasudevan V, Donald J, Slater K, Bennetts B, Bebbington A, Leonard H, Williams SR, Smith RL, Cloosterman D, Christodoulou J. Delineation of large deletions of the MECP2 gene in Rett syndrome patients, including a familial case with a male proband. Eur J Hum Genet 2007; 15:1218-29. [PMID: 17712354 DOI: 10.1038/sj.ejhg.5201911] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Comprehensive genetic screening programs have led to the identification of pathogenic methyl-CpG-binding protein 2 (MECP2) mutations in up to 95% of classical Rett syndrome (RTT) patients. This high rate of mutation detection can partly be attributed to specialised techniques that have enabled the detection of large deletions in a substantial fraction of otherwise mutation-negative patients. These cases would normally be missed by the routine PCR-based screening strategies. Here, we have identified large multi-exonic deletions in 12/149 apparently mutation-negative RTT patients using multiplex ligation-dependent probe amplification (MLPA). These deletions were subsequently characterised using real-time quantitative PCR (qPCR) and long-range PCR with the ultimate aim of defining the exact nucleotide positions of the breakpoints and rearrangements. We detected an apparent deletion in one further patient using MLPA; however, this finding was contradicted by subsequent qPCR and long-range PCR results. The patient group includes an affected brother and sister with a large MECP2 deletion also present in their carrier mother. The X chromosome inactivation pattern of all female patients in this study was determined, which, coupled with detailed clinical information, allowed meaningful genotype-phenotype correlations to be drawn. This study reaffirms the view that large MECP2 deletions are an important cause of both classical and atypical RTT syndrome, and cautions that apparent deletions detected using high-throughput diagnostic techniques require further characterisation.
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Affiliation(s)
- Simon A Hardwick
- Department of Biological Sciences, Macquarie University, Sydney, Australia
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Christodoulou J, Craig HJ, Walker DC, Weaving LS, Pearson CE, McInnes RR. Deletion hotspot in the argininosuccinate lyase gene: association with topoisomerase II and DNA polymerase alpha sites. Hum Mutat 2006; 27:1065-71. [PMID: 16941645 DOI: 10.1002/humu.20352] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Molecular analysis of argininosuccinate lyase (ASAL) deficiency has led to the identification of a deletion hotspot in the ASL gene. Six individuals with ASAL deficiency had alleles that led to a complete absence of exon 13 from the ASL mRNA; each had a partial deletion of exon 13 in the genomic DNA. In all six patients, the deletions begin 18 bp upstream of the 3' end of exon 13. In four cases, the deletions were 13 bp in length, and ended within exon 13, whereas in two other patients the deletions were 25 bp and extended into intron 13. The sequence at which these deletions begin overlaps both a putative topoisomerase II recognition site and a DNA polymerase alpha mutation/frameshift site. Moreover, the topoisomerase II cut site is situated precisely at the beginning of the deletions, which are flanked by small (2- and 3-bp) direct repeats. We note that a similar concurrence of these two putative enzyme sites can be found in a number of other deletion sites in the human genome, most notably the DeltaF508 deletion in the CFTR gene. These findings suggest that the joint presence of these two enzyme sites represents a DNA sequence context that may favor the occurrence of small deletions.
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Affiliation(s)
- John Christodoulou
- Program in Genetics and Genomic Biology, Research Institute, Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada.
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Filipe-Santos O, Bustamante J, Chapgier A, Vogt G, de Beaucoudrey L, Feinberg J, Jouanguy E, Boisson-Dupuis S, Fieschi C, Picard C, Casanova JL. Inborn errors of IL-12/23- and IFN-γ-mediated immunity: molecular, cellular, and clinical features. Semin Immunol 2006; 18:347-61. [PMID: 16997570 DOI: 10.1016/j.smim.2006.07.010] [Citation(s) in RCA: 334] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2006] [Accepted: 07/14/2006] [Indexed: 01/01/2023]
Abstract
Mendelian susceptibility to mycobacterial diseases confers predisposition to clinical disease caused by weakly virulent mycobacterial species in otherwise healthy individuals. Since 1996, disease-causing mutations have been found in five autosomal genes (IFNGR1, IFNGR2, STAT1, IL12B, IL12BR1) and one X-linked gene (NEMO). These genes display a high degree of allelic heterogeneity, defining at least 13 disorders. Although genetically different, these conditions are immunologically related, as all result in impaired IL-12/23-IFN-gamma-mediated immunity. These disorders were initially thought to be rare, but have now been diagnosed in over 220 patients from over 43 countries worldwide. We review here the molecular, cellular, and clinical features of patients with inborn errors of the IL-12/23-IFN-gamma circuit.
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Affiliation(s)
- Orchidée Filipe-Santos
- Laboratory of Human Genetics of Infectious Diseases, University of Paris René Descartes-INSERM U 550, Necker Medical School, 75015 Paris, France, EU
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Morisawa T, Yagi M, Surono A, Yokoyama N, Ohmori M, Terashi H, Matsuo M. Novel double-deletion mutations of the OFD1 gene creating multiple novel transcripts. Hum Genet 2004; 115:97-103. [PMID: 15221448 DOI: 10.1007/s00439-004-1139-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2004] [Accepted: 04/21/2004] [Indexed: 10/26/2022]
Abstract
Oral-facial-digital syndrome type 1 (OFD1) is an X-linked dominant disease characterized by malformations of the face, oral cavity, and digits. Thus far, 18 small mutations in the OFD1 gene have been reported. Here, we describe, in one Japanese sporadic female OFD1 case, the presence of a novel pair of deletion mutations: a 4,094-bp deletion encompassing exon 7 to intron 9, and a 14-bp deletion in intron 9, both of which are present in her paternal X-chromosome. The first deletion, the largest known to affect OFD1, was revealed by identifying four novel transcripts that all lacked exons 7-9. The most likely cause of the double deletion is two unequal recombinations between homologous sequences. Identification of the 4,094-bp deletion was made possible only by analyzing OFD1 mRNA, underscoring the utility of mRNA analysis in the mutational analysis of OFD1.
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Affiliation(s)
- Takeshi Morisawa
- Department of Pediatrics, Kobe University Graduate School of Medicine, 7-5-1 Kusunokicho, Chuo, 650-0017, Kobe, Japan
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Laccone F, Jünemann I, Whatley S, Morgan R, Butler R, Huppke P, Ravine D. Large deletions of the MECP2 gene detected by gene dosage analysis in patients with Rett syndrome. Hum Mutat 2004; 23:234-44. [PMID: 14974082 DOI: 10.1002/humu.20004] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/08/2022]
Abstract
MECP2 mutations are responsible for Rett syndrome (RTT). Approximately a quarter of classic RTT cases, however, do not have an identifiable mutation of the MECP2 gene. We hypothesized that larger deletions arising from a deletion prone region (DPR) occur commonly and are not being routinely detected by the current PCR-mediated screening strategies. We developed and applied a quantitative PCR strategy (qPCR) to samples referred for diagnostic assessment from 140 patients among whom RTT was strongly suspected and from a second selected group of 31 girls with classical RTT. Earlier MECP2 mutation screening in both groups of patients had yielded a wild-type result. We identified 10 large deletions (7.1%) within the first group and five deletions in the second group (16.1%). Sequencing of the breakpoints in 11 cases revealed that eight cases had one breakpoint within the DPR. Among seven cases, the breakpoint distant to the DPR involved one of several Alu repeats. Sequence analysis of the junction sequences revealed that eight cases had complex rearrangements. Examination of the MECP2 genomic sequence reveals that it is highly enriched for repeat elements, with the content of Alu repeats rising to 27.8% in intron 2, in which there was an abundance of breakpoints among our patients. Furthermore, a perfect chi sequence, known to be recombinogenic in E. coli, is located in the DPR. We propose that the chi sequence and Alu repeats are potent factors contributing to genomic rearrangement. We suggest that routine mutation screening in MECP2 should include quantitative analysis of the genomic sequences flanking the DPR.
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Affiliation(s)
- Franco Laccone
- Institute of Human Genetics, University of Göttingen, Germany.
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Schollen E, Smeets E, Deflem E, Fryns JP, Matthijs G. Gross rearrangements in the MECP2 gene in three patients with Rett syndrome: implications for routine diagnosis of Rett syndrome. Hum Mutat 2003; 22:116-20. [PMID: 12872251 DOI: 10.1002/humu.10242] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Since 1999, many laboratories have confirmed that mutations in the MECP2 gene are the primary cause of Rett syndrome (RTT or RS) and identified mutations in 70 to 90% of the sporadically affected girls. Most of the screenings are PCR-based and restricted to the coding part of the gene and therefore prone to miss gross rearrangements. By Southern blot analysis we identified large deletions (>1 kb) in three female patients with classical, severe Rett syndrome. Further characterization by semi-quantitative PCR and amplification of junction fragments confirmed the presence of a 7.6-kb deletion in one patient and an 8.1-kb deletion in the other patient, both including exon 3 and the coding part of exon 4. The exact nature of the rearrangement in the third patient remained elusive. These results underline the importance of screening for major genomic rearrangements in Rett syndrome. Hum Mutat 22:116-120, 2003.
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Affiliation(s)
- E Schollen
- Center for Human Genetics, University of Leuven, Leuven, Belgium
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Abstract
RS, the most common cause of profound cognitive impairment in girls and women, is composed of characteristic clinical features, including communication dysfunction, stereotypic movements, and pervasive growth failure. Neuropathologic findings indicate a failure of neuronal maturation with too small neurons and too few dendritic arbors and no evidence of a progressive neurodegenerative process. The combination of clinical and neuropathologic characteristics presents the profile of a neurodevelopmental disorder. Mutations in the gene MECP2, which encodes MeCP2, have been identified in 80% to 85% of girls and women with RS. Furthermore, the panorama of phenotypes with MECP2 mutations now extends far beyond RS to include normal girls and women, mild learning disability, autistic spectrum disorders, and X-linked mental retardation. These rapid advances in our understanding of RS over the past three decades have opened new avenues of study in developmental neurobiology.
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Affiliation(s)
- Alan K Percy
- Departments of Pediatrics, Neurology, and Neurobiology, University of Alabama, Birmingham School of Medicine, 1600 7th Avenue South, Suite 516, Birmingham, AL 35233, USA.
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Van den Veyver IB, Zoghbi HY. Genetic basis of Rett syndrome. MENTAL RETARDATION AND DEVELOPMENTAL DISABILITIES RESEARCH REVIEWS 2002; 8:82-6. [PMID: 12112732 DOI: 10.1002/mrdd.10025] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The origin of Rett syndrome has long been debated, but several observations have suggested an X-linked dominant inheritance pattern. We and others have pursued an exclusion-mapping strategy using DNA from a small number of familial Rett syndrome cases. This work resulted in the narrowing of the region likely to harbor the mutated gene to Xq27.3-Xqter. After systematic exclusion of several candidate genes, we discovered mutations in MECP2, the gene that encodes the transcriptional repressor, methyl-CpG-binding protein 2. Since then, nonsense, missense, or frameshift mutations have been found in at least 80% of girls affected with classic Rett syndrome. Sixty-four percent of mutations are recurrent C > T transitions at eight CpG dinucleotides mutation hotspots, while the C-terminal region of the gene is prone to recurrent multinucleotide deletions (11%). Most mutations are predicted to result in total or partial loss of function of MeCP2. There is no clear correlation between the type and position of the mutation and the phenotypic features of classic and variant Rett syndrome patients, and XCI appears to be a major determinant of phenotypic severity. Further research focuses on the pathogenic consequences of these mutations along the hypothesis of loss of transcriptional repression of a small number of genes that are essential for neuronal function in the maturing brain.
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Milunsky JM, Lebo RV, Ikuta T, Maher TA, Haverty CE, Milunsky A. Mutation analysis in Rett syndrome. GENETIC TESTING 2002; 5:321-5. [PMID: 11960578 DOI: 10.1089/109065701753617462] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Rett syndrome is an X-linked dominant neurodevelopmental disorder caused by mutations in the MECP2 gene. Mutations have been demonstrated in more than 80% of females with typical features of Rett syndrome. We identified mutations in the MECP2 gene and documented the clinical manifestations in 65 Rett syndrome patients to characterize the genotype-phenotype spectrum. Bidirectional sequencing of the entire MECP2 coding region was performed. We diagnosed 65 patients with MECP2 mutations. Of these, 15 mutations had been reported previously and 13 are novel. Two patients have multiple deletions within the MECP2 gene. Eight common mutations were found in 43 of 65 patients (66.15%). The majority of patients with identified mutations have the classic Rett phenotype, and several had atypical phenotypes. MECP2 analysis identified mutations in almost all cases of typical Rett syndrome, as well as in some with atypical phenotypes. Eleven (20.4%) of the 54 patients with defined mutations and in whom phenotypic data were obtained did not develop acquired microcephaly. Hence, microcephaly at birth or absence of acquired microcephaly does not obviate the need for MECP2 analysis. We have initiated cascade testing starting with PCR analysis for common mutations followed by sequencing, when necessary. Analysis of common mutations before sequencing the entire gene is anticipated to be the most efficacious strategy to identify Rett syndrome gene mutations.
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Affiliation(s)
- J M Milunsky
- Center for Human Genetics and the Department of Pediatrics, Boston University School of Medicine, Boston, MA 02118, USA.
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