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Grosz BR, Parmar JM, Ellis M, Bryen S, Simons C, Reis ALM, Stevanovski I, Deveson IW, Nicholson G, Laing N, Wallis M, Ravenscroft G, Kumar KR, Vucic S, Kennerson ML. A deep intronic variant in MME causes autosomal recessive Charcot-Marie-Tooth neuropathy through aberrant splicing. J Peripher Nerv Syst 2024. [PMID: 38860315 DOI: 10.1111/jns.12637] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2024] [Revised: 05/26/2024] [Accepted: 05/28/2024] [Indexed: 06/12/2024]
Abstract
BACKGROUND Loss-of-function variants in MME (membrane metalloendopeptidase) are a known cause of recessive Charcot-Marie-Tooth Neuropathy (CMT). A deep intronic variant, MME c.1188+428A>G (NM_000902.5), was identified through whole genome sequencing (WGS) of two Australian families with recessive inheritance of axonal CMT using the seqr platform. MME c.1188+428A>G was detected in a homozygous state in Family 1, and in a compound heterozygous state with a known pathogenic MME variant (c.467del; p.Pro156Leufs*14) in Family 2. AIMS We aimed to determine the pathogenicity of the MME c.1188+428A>G variant through segregation and splicing analysis. METHODS The splicing impact of the deep intronic MME variant c.1188+428A>G was assessed using an in vitro exon-trapping assay. RESULTS The exon-trapping assay demonstrated that the MME c.1188+428A>G variant created a novel splice donor site resulting in the inclusion of an 83 bp pseudoexon between MME exons 12 and 13. The incorporation of the pseudoexon into MME transcript is predicted to lead to a coding frameshift and premature termination codon (PTC) in MME exon 14 (p.Ala397ProfsTer47). This PTC is likely to result in nonsense mediated decay (NMD) of MME transcript leading to a pathogenic loss-of-function. INTERPRETATION To our knowledge, this is the first report of a pathogenic deep intronic MME variant causing CMT. This is of significance as deep intronic variants are missed using whole exome sequencing screening methods. Individuals with CMT should be reassessed for deep intronic variants, with splicing impacts being considered in relation to the potential pathogenicity of variants.
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Affiliation(s)
- Bianca R Grosz
- Northcott Neuroscience Laboratory, ANZAC Research Institute, Sydney, New South Wales, Australia
- The University of Sydney, Camperdown, New South Wales, Australia
| | - Jevin M Parmar
- Rare Disease Genetics and Functional Genomics Research Group, Harry Perkins Institute of Medical Research, QEII Medical Centre, Nedlands, Western Australia, Australia
- Centre for Medical Research, Faculty of Health and Medical Sciences, The University of Western Australia, Perth, Western Australia, Australia
| | - Melina Ellis
- Northcott Neuroscience Laboratory, ANZAC Research Institute, Sydney, New South Wales, Australia
- The University of Sydney, Camperdown, New South Wales, Australia
| | - Samantha Bryen
- Centre for Population Genomics, Garvan Institute of Medical Research, and UNSW Sydney, Sydney, New South Wales, Australia
- Centre for Population Genomics, Murdoch Children's Research Institute, Melbourne, Victoria, Australia
| | - Cas Simons
- Centre for Population Genomics, Garvan Institute of Medical Research, and UNSW Sydney, Sydney, New South Wales, Australia
- Centre for Population Genomics, Murdoch Children's Research Institute, Melbourne, Victoria, Australia
| | - Andre L M Reis
- Centre for Population Genomics, Garvan Institute of Medical Research, and UNSW Sydney, Sydney, New South Wales, Australia
- Genomics and Inherited Disease Program, Garvan Institute of Medical Research, Sydney, New South Wales, Australia
- Faculty of Medicine, University of New South Wales, Sydney, New South Wales, Australia
| | - Igor Stevanovski
- Centre for Population Genomics, Garvan Institute of Medical Research, and UNSW Sydney, Sydney, New South Wales, Australia
- Genomics and Inherited Disease Program, Garvan Institute of Medical Research, Sydney, New South Wales, Australia
| | - Ira W Deveson
- Centre for Population Genomics, Garvan Institute of Medical Research, and UNSW Sydney, Sydney, New South Wales, Australia
- Genomics and Inherited Disease Program, Garvan Institute of Medical Research, Sydney, New South Wales, Australia
- Faculty of Medicine, University of New South Wales, Sydney, New South Wales, Australia
| | - Garth Nicholson
- The University of Sydney, Camperdown, New South Wales, Australia
- Molecular Medicine Laboratory and Neurology Department, Concord Repatriation General Hospital, Concord, New South Wales, Australia
| | - Nigel Laing
- Rare Disease Genetics and Functional Genomics Research Group, Harry Perkins Institute of Medical Research, QEII Medical Centre, Nedlands, Western Australia, Australia
| | - Mathew Wallis
- Tasmanian Clinical Genetics Service, Tasmanian Health Service, Hobart, Australia
- School of Medicine and Menzies Institute for Medical Research, University of Tasmania, Hobart, Australia
| | - Gianina Ravenscroft
- Rare Disease Genetics and Functional Genomics Research Group, Harry Perkins Institute of Medical Research, QEII Medical Centre, Nedlands, Western Australia, Australia
| | - Kishore R Kumar
- The University of Sydney, Camperdown, New South Wales, Australia
- Molecular Medicine Laboratory and Neurology Department, Concord Repatriation General Hospital, Concord, New South Wales, Australia
- Translational Neurogenomics Group, Genomic and Inherited Disease Program, The Garvan Institute of Medical Research, Darlinghurst, New South Wales, Australia
- St Vincent's Healthcare Campus, Faculty of Medicine, UNSW Sydney, Darlinghurst, New South Wales, Australia
| | - Steve Vucic
- The University of Sydney, Camperdown, New South Wales, Australia
- Brain and Nerve Research Centre, The University of Sydney, Sydney, New South Wales, Australia
| | - Marina L Kennerson
- Northcott Neuroscience Laboratory, ANZAC Research Institute, Sydney, New South Wales, Australia
- The University of Sydney, Camperdown, New South Wales, Australia
- Molecular Medicine Laboratory and Neurology Department, Concord Repatriation General Hospital, Concord, New South Wales, Australia
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Man A, Di Scipio M, Grewal S, Suk Y, Trinari E, Ejaz R, Whitney R. The Genetics of Tuberous Sclerosis Complex and Related mTORopathies: Current Understanding and Future Directions. Genes (Basel) 2024; 15:332. [PMID: 38540392 PMCID: PMC10970281 DOI: 10.3390/genes15030332] [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: 02/12/2024] [Revised: 03/02/2024] [Accepted: 03/02/2024] [Indexed: 06/14/2024] Open
Abstract
The mechanistic target of rapamycin (mTOR) pathway serves as a master regulator of cell growth, proliferation, and survival. Upregulation of the mTOR pathway has been shown to cause malformations of cortical development, medically refractory epilepsies, and neurodevelopmental disorders, collectively described as mTORopathies. Tuberous sclerosis complex (TSC) serves as the prototypical mTORopathy. Characterized by the development of benign tumors in multiple organs, pathogenic variants in TSC1 or TSC2 disrupt the TSC protein complex, a negative regulator of the mTOR pathway. Variants in critical domains of the TSC complex, especially in the catalytic TSC2 subunit, correlate with increased disease severity. Variants in less crucial exons and non-coding regions, as well as those undetectable with conventional testing, may lead to milder phenotypes. Despite the assumption of complete penetrance, expressivity varies within families, and certain variants delay disease onset with milder neurological effects. Understanding these genotype-phenotype correlations is crucial for effective clinical management. Notably, 15% of patients have no mutation identified by conventional genetic testing, with the majority of cases postulated to be caused by somatic TSC1/TSC2 variants which present complex diagnostic challenges. Advancements in genetic testing, prenatal screening, and precision medicine hold promise for changing the diagnostic and treatment paradigm for TSC and related mTORopathies. Herein, we explore the genetic and molecular mechanisms of TSC and other mTORopathies, emphasizing contemporary genetic methods in understanding and diagnosing the condition.
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Affiliation(s)
- Alice Man
- Michael G. DeGroote School of Medicine, McMaster University, Hamilton, ON L8S 4L8, Canada
| | - Matteo Di Scipio
- Michael G. DeGroote School of Medicine, McMaster University, Hamilton, ON L8S 4L8, Canada
| | - Shan Grewal
- Michael G. DeGroote School of Medicine, McMaster University, Hamilton, ON L8S 4L8, Canada
| | - Yujin Suk
- Michael G. DeGroote School of Medicine, McMaster University, Hamilton, ON L8S 4L8, Canada
| | - Elisabetta Trinari
- Division of Developmental Pediatrics, Department of Pediatrics, McMaster Children’s Hospital, Hamilton, ON L8N 3Z5, Canada
| | - Resham Ejaz
- Division of Genetics, Department of Pediatrics, McMaster University, Hamilton, ON L8S 4L8, Canada
| | - Robyn Whitney
- Division of Neurology, Department of Pediatrics, McMaster University, Hamilton, ON L8S 4L8, Canada
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3
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Viering DH, Hureaux M, Neveling K, Latta F, Kwint M, Blanchard A, Konrad M, Bindels RJ, Schlingmann KP, Vargas-Poussou R, de Baaij JH. Long-Read Sequencing Identifies Novel Pathogenic Intronic Variants in Gitelman Syndrome. J Am Soc Nephrol 2023; 34:333-345. [PMID: 36302598 PMCID: PMC10103101 DOI: 10.1681/asn.2022050627] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Accepted: 10/17/2022] [Indexed: 02/04/2023] Open
Abstract
BACKGROUND Gitelman syndrome is a salt-losing tubulopathy characterized by hypokalemic alkalosis and hypomagnesemia. It is caused by homozygous recessive or compound heterozygous pathogenic variants in SLC12A3 , which encodes the Na + -Cl - cotransporter (NCC). In up to 10% of patients with Gitelman syndrome, current genetic techniques detect only one specific pathogenic variant. This study aimed to identify a second pathogenic variant in introns, splice sites, or promoters to increase the diagnostic yield. METHODS Long-read sequencing of SLC12A3 was performed in 67 DNA samples from individuals with suspected Gitelman syndrome in whom a single likely pathogenic or pathogenic variant was previously detected. In addition, we sequenced DNA samples from 28 individuals with one variant of uncertain significance or no candidate variant. Midigene splice assays assessed the pathogenicity of novel intronic variants. RESULTS A second likely pathogenic/pathogenic variant was identified in 45 (67%) patients. Those with two likely pathogenic/pathogenic variants had a more severe electrolyte phenotype than other patients. Of the 45 patients, 16 had intronic variants outside of canonic splice sites (nine variants, mostly deep intronic, six novel), whereas 29 patients had an exonic variant or canonic splice site variant. Midigene splice assays of the previously known c.1670-191C>T variant and intronic candidate variants demonstrated aberrant splicing patterns. CONCLUSION Intronic pathogenic variants explain an important part of the missing heritability in Gitelman syndrome. Long-read sequencing should be considered in diagnostic workflows for Gitelman syndrome.
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Affiliation(s)
- Daan H.H.M. Viering
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Marguerite Hureaux
- Reference Center for Hereditary Kidney and Childhood Diseases (Maladies Rénales Héréditaires de l’Enfant et de l’Adulte, MARHEA), Paris, France
- Department of Genetics, Hôpital Européen Georges-Pompidou, Assistance Publique Hôpitaux de Paris, Paris, France
- Paris CardioVascular Research Center, Institut National de la Santé et de Recherche Médicale (INSERM) U970, Paris City University, Paris, France
| | - Kornelia Neveling
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Femke Latta
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Michael Kwint
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Anne Blanchard
- Reference Center for Hereditary Kidney and Childhood Diseases (Maladies Rénales Héréditaires de l’Enfant et de l’Adulte, MARHEA), Paris, France
- Clinical Investigations Center, Hôpital Européen Georges-Pompidou, Assistance Publique Hôpitaux de Paris, Paris, France
- Centre de Recherche des Cordeliers, Sorbonne Université, INSERM, University of Paris, Centre National de la Recherche Scientifique (CNRS), Paris, France
| | - Martin Konrad
- Department of General Pediatrics, University Children’s Hospital, Münster, Germany
| | - René J.M. Bindels
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands
| | | | - Rosa Vargas-Poussou
- Reference Center for Hereditary Kidney and Childhood Diseases (Maladies Rénales Héréditaires de l’Enfant et de l’Adulte, MARHEA), Paris, France
- Department of Genetics, Hôpital Européen Georges-Pompidou, Assistance Publique Hôpitaux de Paris, Paris, France
- Clinical Investigations Center, Hôpital Européen Georges-Pompidou, Assistance Publique Hôpitaux de Paris, Paris, France
| | - Jeroen H.F. de Baaij
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands
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Daich Varela M, Bellingham J, Motta F, Jurkute N, Ellingford JM, Quinodoz M, Oprych K, Niblock M, Janeschitz-Kriegl L, Kaminska K, Cancellieri F, Scholl HPN, Lenassi E, Schiff E, Knight H, Black G, Rivolta C, Cheetham ME, Michaelides M, Mahroo OA, Moore AT, Webster AR, Arno G. Multidisciplinary team directed analysis of whole genome sequencing reveals pathogenic non-coding variants in molecularly undiagnosed inherited retinal dystrophies. Hum Mol Genet 2022; 32:595-607. [PMID: 36084042 PMCID: PMC9896476 DOI: 10.1093/hmg/ddac227] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 08/23/2022] [Accepted: 09/04/2022] [Indexed: 02/07/2023] Open
Abstract
The purpose of this paper is to identify likely pathogenic non-coding variants in inherited retinal dystrophy (IRD) genes, using genome sequencing (GS). Patients with IRD were recruited to the study and underwent comprehensive ophthalmological evaluation and GS. The results of GS were investigated through virtual gene panel analysis, and plausible pathogenic variants and clinical phenotype evaluated by the multidisciplinary team (MDT) discussion. For unsolved patients in whom a specific gene was suspected to harbor a missed pathogenic variant, targeted re-analysis of non-coding regions was performed on GS data. Candidate variants were functionally tested by messenger RNA analysis, minigene or luciferase reporter assays. Previously unreported, likely pathogenic, non-coding variants in 7 genes (PRPF31, NDP, IFT140, CRB1, USH2A, BBS10 and GUCY2D), were identified in 11 patients. These were shown to lead to mis-splicing (PRPF31, IFT140, CRB1 and USH2A) or altered transcription levels (BBS10 and GUCY2D). MDT-led, phenotype-driven, non-coding variant re-analysis of GS is effective in identifying the missing causative alleles.
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Affiliation(s)
- Malena Daich Varela
- UCL Institute of Ophthalmology, London EC1V 9EL, UK,Moorfields Eye Hospital, London EC1V 2PD, UK
| | | | - Fabiana Motta
- UCL Institute of Ophthalmology, London EC1V 9EL, UK,Department of Ophthalmology, Universidade Federal de Sao Paulo, Sao Paulo 04021001, Brazil
| | - Neringa Jurkute
- UCL Institute of Ophthalmology, London EC1V 9EL, UK,Moorfields Eye Hospital, London EC1V 2PD, UK
| | - Jamie M Ellingford
- North West Genomic Laboratory Hub, Manchester Centre for Genomic Medicine, Manchester University Hospitals NHS Foundation Trust, St Mary’s Hospital, Manchester M13 9WL, UK,Division of Evolution and Genomic Sciences, Neuroscience and Mental Health Domain, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PL, UK
| | - Mathieu Quinodoz
- Institute of Molecular and Clinical Ophthalmology Basel, Basel 4031, Switzerland,Department of Ophthalmology, University of Basel, Basel 4031, Switzerland,Department of Genetics and Genome Biology, University of Leicester, Leicester LE1 7RH, UK
| | | | | | - Lucas Janeschitz-Kriegl
- Institute of Molecular and Clinical Ophthalmology Basel, Basel 4031, Switzerland,Department of Ophthalmology, University of Basel, Basel 4031, Switzerland
| | - Karolina Kaminska
- Institute of Molecular and Clinical Ophthalmology Basel, Basel 4031, Switzerland,Department of Ophthalmology, University of Basel, Basel 4031, Switzerland
| | - Francesca Cancellieri
- Institute of Molecular and Clinical Ophthalmology Basel, Basel 4031, Switzerland,Department of Ophthalmology, University of Basel, Basel 4031, Switzerland
| | - Hendrik P N Scholl
- Institute of Molecular and Clinical Ophthalmology Basel, Basel 4031, Switzerland,Department of Ophthalmology, University of Basel, Basel 4031, Switzerland
| | - Eva Lenassi
- North West Genomic Laboratory Hub, Manchester Centre for Genomic Medicine, Manchester University Hospitals NHS Foundation Trust, St Mary’s Hospital, Manchester M13 9WL, UK,Division of Evolution and Genomic Sciences, Neuroscience and Mental Health Domain, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PL, UK
| | | | | | - Graeme Black
- North West Genomic Laboratory Hub, Manchester Centre for Genomic Medicine, Manchester University Hospitals NHS Foundation Trust, St Mary’s Hospital, Manchester M13 9WL, UK,Division of Evolution and Genomic Sciences, Neuroscience and Mental Health Domain, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PL, UK
| | - Carlo Rivolta
- Institute of Molecular and Clinical Ophthalmology Basel, Basel 4031, Switzerland,Department of Ophthalmology, University of Basel, Basel 4031, Switzerland,Department of Genetics and Genome Biology, University of Leicester, Leicester LE1 7RH, UK
| | | | - Michel Michaelides
- UCL Institute of Ophthalmology, London EC1V 9EL, UK,Moorfields Eye Hospital, London EC1V 2PD, UK
| | - Omar A Mahroo
- UCL Institute of Ophthalmology, London EC1V 9EL, UK,Moorfields Eye Hospital, London EC1V 2PD, UK
| | - Anthony T Moore
- UCL Institute of Ophthalmology, London EC1V 9EL, UK,Moorfields Eye Hospital, London EC1V 2PD, UK,University of California, San Francisco, CA 94607, USA
| | - Andrew R Webster
- UCL Institute of Ophthalmology, London EC1V 9EL, UK,Moorfields Eye Hospital, London EC1V 2PD, UK
| | - Gavin Arno
- To whom correspondence should be addressed at: UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1 9EL, UK. Tel: +44 2076086971;
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Dvaladze A, Tavares E, Di Scipio M, Nimmo G, Grudzinska-Pechhacker MK, Paton T, Tumber A, Li S, Eileen C, Ertl-Wagner B, Mamak E, Hoffmann G, Marshall CR, Haas D, Mayatepek E, Schulze A, Heon E, Vincent A. Deep Intronic Variant in MVK as a Cause for Mevalonic Aciduria Initially Presenting as Non-syndromic Retinitis Pigmentosa. Clin Genet 2022; 102:524-529. [PMID: 35916082 DOI: 10.1111/cge.14207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2022] [Revised: 07/25/2022] [Accepted: 07/27/2022] [Indexed: 11/29/2022]
Abstract
Non-syndromic retinitis pigmentosa (NSRP) is a clinically and genetically heterogeneous group of disorders characterized by progressive degeneration of the rod and cone photoreceptors, often leading to blindness. The evolving association of syndromic genes to cause NSRP and the increasing role of intronic variants in explaining missing heritability in genetic disorders present challenges in establishing conclusive clinical and genetic diagnoses. This study sought to identify and validate the causative genetic variant(s) in a 13-year-old male initially diagnosed with NSRP. Genome sequencing identified a pathogenic missense variant in MVK [NM_000431.3:c.803T>C (p. Ile268Thr)], in trans with a novel intronic variant predicted to create a new donor splice site (c.768+71C>A). Proband cDNA analysis confirmed the inclusion of the first 68 base pairs of intron 8 that resulted in a frameshift in MVK (r.768_769ins[768+1_768+68]) and significantly reduced the expression of reference transcript (17.6%). Patient re-phenotyping revealed ataxia, cerebellar atrophy, elevated urinary mevalonate and LTE4 , in keeping with mild mevalonic aciduria and associated syndromic retinitis pigmentosa. Leakage of reference transcript likely explains the milder phenotype observed. This is the first association of a deep intronic splice variant to cause MVK-related disorder. This report highlights the importance of variant validation and patient re-phenotyping in establishing accurate diagnosis in the era of genome sequencing.
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Affiliation(s)
- Anna Dvaladze
- Genetics and Genome Biology, The Hospital for Sick Children (HSC), Toronto, Canada
| | - Erika Tavares
- Genetics and Genome Biology, The Hospital for Sick Children (HSC), Toronto, Canada
| | - Matteo Di Scipio
- Genetics and Genome Biology, The Hospital for Sick Children (HSC), Toronto, Canada
| | - Graeme Nimmo
- Clinical and Metabolic Genetics, HSC, Canada.,Fred A Litwin Family Centre for Genetic Medicine, The University Health Network, Toronto, Canada
| | - Monika K Grudzinska-Pechhacker
- Genetics and Genome Biology, The Hospital for Sick Children (HSC), Toronto, Canada.,Department of Ophthalmology and Vision Sciences, HSC and University of Toronto, Canada
| | - Tara Paton
- The Centre for Applied Genomics, HSC, Canada
| | - Anupreet Tumber
- Department of Ophthalmology and Vision Sciences, HSC and University of Toronto, Canada
| | - Shuning Li
- Genetics and Genome Biology, The Hospital for Sick Children (HSC), Toronto, Canada
| | - Christabel Eileen
- Genetics and Genome Biology, The Hospital for Sick Children (HSC), Toronto, Canada
| | - Birgit Ertl-Wagner
- Division of Neuroradiology, HSC, Canada.,Department of Medical Imaging, University of Toronto, Canada
| | - Eva Mamak
- Department of Psychology, HSC, Canada
| | - Georg Hoffmann
- Neuropaediatrics and Paediatric Metabolic Medicine, University Hospital Heidelberg, Germany
| | | | - Dorothea Haas
- Neuropaediatrics and Paediatric Metabolic Medicine, University Hospital Heidelberg, Germany
| | - Ertan Mayatepek
- Department of General Paediatrics, Neonatology and Paediatric Cardiology, University Children's Hospital, Heinrich Heine University, Dusseldorf, Germany
| | - Andreas Schulze
- Clinical and Metabolic Genetics, HSC, Canada.,Department of Paediatrics, University of Toronto, Canada.,Department of Biochemistry, University of Toronto, Canada
| | - Elise Heon
- Genetics and Genome Biology, The Hospital for Sick Children (HSC), Toronto, Canada.,Department of Ophthalmology and Vision Sciences, HSC and University of Toronto, Canada
| | - Ajoy Vincent
- Genetics and Genome Biology, The Hospital for Sick Children (HSC), Toronto, Canada.,Department of Ophthalmology and Vision Sciences, HSC and University of Toronto, Canada
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Rabie EA, Sayed ISM, Amr K, Ahmed HA, Mostafa MI, Hassib NF, El-Sayed H, Zada SK, El-Kamah G. Confirmation of a Phenotypic Entity for TSPEAR Variants in Egyptian Ectodermal Dysplasia Patients and Role of Ethnicity. Genes (Basel) 2022; 13:genes13061056. [PMID: 35741818 PMCID: PMC9222913 DOI: 10.3390/genes13061056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Revised: 06/07/2022] [Accepted: 06/09/2022] [Indexed: 02/01/2023] Open
Abstract
Ectodermal dysplasia (ED) are hereditary disorders characterized by the disturbance of the ectodermal development of at least two of four ectodermal tissues: teeth, hair, nails and sweat glands. Clinical classification of ED is challenged by overlapping features, variable expressivity, and low number of patients, hindering full phenotypic spectrum identification. Disease-causing variants in elements of major developmental pathways, e.g., Ectodysplasin/NFκB, Wnt, and Tp63 pathways, have been identified in fewer than half of ED phenotypes. Whole-exome sequencing (WES) was performed for ten Egyptian ED patients presenting with tooth agenesis, normal sweating, scalp hypotrichosis, and sharing characteristic facial features. WES was followed by in silico analysis of the effects of novel detected genetic variants on mRNA and protein structure. The study identified four novel rare pathogenic and likely pathogenic TSPEAR variants, a gene which was recently found to be involved in ectodermal organogenesis. A novel in-frame deletion recurred in eight patients from six unrelated families. Comparing our cohort to previously reported TSPEAR cohorts highlighted the influence of ethnicity on TSPEAR phenotypic affection. Our study expands the clinical and mutational spectrum of the growing TSPEAR associated phenotypes, and pinpoints the influence of WES and in silico tools on identification of rare disease-causing variants.
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Affiliation(s)
- Eman A. Rabie
- Medical Molecular Genetics Department, Human Genetics & Genome Research Division (HGGR), National Research Centre (NRC), Cairo 12622, Egypt;
- Biology Department, School of Sciences and Engineering, The American University in Cairo (AUC), Cairo 11835, Egypt;
- Correspondence: (E.A.R.); (K.A.); (G.E.-K.)
| | - Inas S. M. Sayed
- Orodental Genetics Department, Human Genetics & Genome Research Division (HGGR), National Research Centre (NRC), Cairo 12622, Egypt; (I.S.M.S.); (M.I.M.); (N.F.H.)
| | - Khalda Amr
- Medical Molecular Genetics Department, Human Genetics & Genome Research Division (HGGR), National Research Centre (NRC), Cairo 12622, Egypt;
- Correspondence: (E.A.R.); (K.A.); (G.E.-K.)
| | - Hoda A. Ahmed
- Medical Molecular Genetics Department, Human Genetics & Genome Research Division (HGGR), National Research Centre (NRC), Cairo 12622, Egypt;
| | - Mostafa I. Mostafa
- Orodental Genetics Department, Human Genetics & Genome Research Division (HGGR), National Research Centre (NRC), Cairo 12622, Egypt; (I.S.M.S.); (M.I.M.); (N.F.H.)
| | - Nehal F. Hassib
- Orodental Genetics Department, Human Genetics & Genome Research Division (HGGR), National Research Centre (NRC), Cairo 12622, Egypt; (I.S.M.S.); (M.I.M.); (N.F.H.)
| | - Heba El-Sayed
- Clinical Genetics Department, Human Genetics & Genome Research Division (HGGR), National Research Centre (NRC), Cairo 12622, Egypt;
| | - Suher K. Zada
- Biology Department, School of Sciences and Engineering, The American University in Cairo (AUC), Cairo 11835, Egypt;
| | - Ghada El-Kamah
- Clinical Genetics Department, Human Genetics & Genome Research Division (HGGR), National Research Centre (NRC), Cairo 12622, Egypt;
- Correspondence: (E.A.R.); (K.A.); (G.E.-K.)
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Mustafi D, Hisama FM, Huey J, Chao JR. The current state of genetic testing platforms for inherited retinal diseases. Ophthalmol Retina 2022; 6:702-710. [PMID: 35307606 PMCID: PMC9356993 DOI: 10.1016/j.oret.2022.03.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 03/08/2022] [Accepted: 03/14/2022] [Indexed: 11/30/2022]
Abstract
PURPOSE To evaluate genetic testing platforms used to aid in the diagnosis of inherited retinal degenerations (IRDs). DESIGN Evaluation of diagnostic test or technology SUBJECTS: Targeted genetic panel testing for IRDs METHODS, INTERVENTION, OR TESTING: Data collected regarding targeted genetic panel testing for IRDs offered by different labs were investigated for inclusion of coding and non-coding variants in disease genes. Both large IRD panels and smaller, more focused disease specific panels were included in the analysis. MAIN OUTCOME MEASURES Number of disease genes tested as well as the commonality and uniqueness across testing platforms in both coding and non-coding variants of disease. RESULTS Across the three IRD panel tests investigated, 409 unique genes are represented, of which 269 genes are tested by all three panels. The top 20 genes known to cause over 70% of all IRDs are represented in the 269 common genes tested by all three panels. In addition, 138 non-coding variants are assayed across the three platforms in 50 unique genes. Focused disease specific panels exhibited significant variability across 5 testing platforms that were studied. CONCLUSIONS Ordering genetic testing for IRDs is not straightforward, as evidenced by the multitude of panels available to providers. It is important that there is coverage of both coding and non-coding regions in IRD genes to offer a diagnosis in these patients. This paper details the diversity of testing platforms currently available to clinicians and provides a thorough explanation of genes tested in the different IRD panels. In a time of increased importance for clinical genetic testing of IRD patients, knowledge of the proper test to order is paramount.
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Affiliation(s)
- Debarshi Mustafi
- Department of Ophthalmology, University of Washington, Seattle, Washington; Department of Ophthalmology, Seattle Children's Hospital, Seattle, Washington.
| | - Fuki M Hisama
- Division of Medical Genetics, Department of Medicine, University of Washington, Seattle, Washington
| | - Jennifer Huey
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington
| | - Jennifer R Chao
- Department of Ophthalmology, University of Washington, Seattle, Washington
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8
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Keegan NP, Wilton SD, Fletcher S. Analysis of Pathogenic Pseudoexons Reveals Novel Mechanisms Driving Cryptic Splicing. Front Genet 2022; 12:806946. [PMID: 35140743 PMCID: PMC8819188 DOI: 10.3389/fgene.2021.806946] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Accepted: 12/09/2021] [Indexed: 12/16/2022] Open
Abstract
Understanding pre-mRNA splicing is crucial to accurately diagnosing and treating genetic diseases. However, mutations that alter splicing can exert highly diverse effects. Of all the known types of splicing mutations, perhaps the rarest and most difficult to predict are those that activate pseudoexons, sometimes also called cryptic exons. Unlike other splicing mutations that either destroy or redirect existing splice events, pseudoexon mutations appear to create entirely new exons within introns. Since exon definition in vertebrates requires coordinated arrangements of numerous RNA motifs, one might expect that pseudoexons would only arise when rearrangements of intronic DNA create novel exons by chance. Surprisingly, although such mutations do occur, a far more common cause of pseudoexons is deep-intronic single nucleotide variants, raising the question of why these latent exon-like tracts near the mutation sites have not already been purged from the genome by the evolutionary advantage of more efficient splicing. Possible answers may lie in deep intronic splicing processes such as recursive splicing or poison exon splicing. Because these processes utilize intronic motifs that benignly engage with the spliceosome, the regions involved may be more susceptible to exonization than other intronic regions would be. We speculated that a comprehensive study of reported pseudoexons might detect alignments with known deep intronic splice sites and could also permit the characterisation of novel pseudoexon categories. In this report, we present and analyse a catalogue of over 400 published pseudoexon splice events. In addition to confirming prior observations of the most common pseudoexon mutation types, the size of this catalogue also enabled us to suggest new categories for some of the rarer types of pseudoexon mutation. By comparing our catalogue against published datasets of non-canonical splice events, we also found that 15.7% of pseudoexons exhibit some splicing activity at one or both of their splice sites in non-mutant cells. Importantly, this included seven examples of experimentally confirmed recursive splice sites, confirming for the first time a long-suspected link between these two splicing phenomena. These findings have the potential to improve the fidelity of genetic diagnostics and reveal new targets for splice-modulating therapies.
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Affiliation(s)
- Niall P. Keegan
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Perth, WA, Australia
- Centre for Neuromuscular and Neurological Disorders, Perron Institute for Neurological and Translational Science, The University of Western Australia, Perth, WA, Australia
- *Correspondence: Niall P. Keegan,
| | - Steve D. Wilton
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Perth, WA, Australia
- Centre for Neuromuscular and Neurological Disorders, Perron Institute for Neurological and Translational Science, The University of Western Australia, Perth, WA, Australia
| | - Sue Fletcher
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Perth, WA, Australia
- Centre for Neuromuscular and Neurological Disorders, Perron Institute for Neurological and Translational Science, The University of Western Australia, Perth, WA, Australia
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9
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Fadaie Z, Whelan L, Ben-Yosef T, Dockery A, Corradi Z, Gilissen C, Haer-Wigman L, Corominas J, Astuti GDN, de Rooij L, van den Born LI, Klaver CCW, Hoyng CB, Wynne N, Duignan ES, Kenna PF, Cremers FPM, Farrar GJ, Roosing S. Whole genome sequencing and in vitro splice assays reveal genetic causes for inherited retinal diseases. NPJ Genom Med 2021; 6:97. [PMID: 34795310 PMCID: PMC8602293 DOI: 10.1038/s41525-021-00261-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Accepted: 10/21/2021] [Indexed: 01/08/2023] Open
Abstract
Inherited retinal diseases (IRDs) are a major cause of visual impairment. These clinically heterogeneous disorders are caused by pathogenic variants in more than 270 genes. As 30-40% of cases remain genetically unexplained following conventional genetic testing, we aimed to obtain a genetic diagnosis in an IRD cohort in which the genetic cause was not found using whole-exome sequencing or targeted capture sequencing. We performed whole-genome sequencing (WGS) to identify causative variants in 100 unresolved cases. After initial prioritization, we performed an in-depth interrogation of all noncoding and structural variants in genes when one candidate variant was detected. In addition, functional analysis of putative splice-altering variants was performed using in vitro splice assays. We identified the genetic cause of the disease in 24 patients. Causative coding variants were observed in genes such as ATXN7, CEP78, EYS, FAM161A, and HGSNAT. Gene disrupting structural variants were also detected in ATXN7, PRPF31, and RPGRIP1. In 14 monoallelic cases, we prioritized candidate noncanonical splice sites or deep-intronic variants that were predicted to disrupt the splicing process based on in silico analyses. Of these, seven cases were resolved as they carried pathogenic splice defects. WGS is a powerful tool to identify causative variants residing outside coding regions or heterozygous structural variants. This approach was most efficient in cases with a distinct clinical diagnosis. In addition, in vitro splice assays provide important evidence of the pathogenicity of rare variants.
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Affiliation(s)
- Zeinab Fadaie
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
- Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Laura Whelan
- The School of Genetics and Microbiology, Smurfit Institute of Genetics, Trinity College Dublin, Dublin, Ireland
| | - Tamar Ben-Yosef
- Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Adrian Dockery
- The School of Genetics and Microbiology, Smurfit Institute of Genetics, Trinity College Dublin, Dublin, Ireland
| | - Zelia Corradi
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
- Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Christian Gilissen
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
- Radboud Institute of Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Lonneke Haer-Wigman
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Jordi Corominas
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
- Radboud Institute of Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Galuh D N Astuti
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
- Division of Human Genetics, Center for Biomedical Research (CEBIOR), Faculty of Medicine, Diponegoro University, Semarang, Indonesia
| | - Laura de Rooij
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | | | - Caroline C W Klaver
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Ophthalmology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Carel B Hoyng
- Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, Nijmegen, The Netherlands
- Department of Ophthalmology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Niamh Wynne
- Department of Ophthalmology, Royal Victoria Eye and Ear Hospital, Dublin, Ireland
| | - Emma S Duignan
- Department of Ophthalmology, Royal Victoria Eye and Ear Hospital, Dublin, Ireland
| | - Paul F Kenna
- The School of Genetics and Microbiology, Smurfit Institute of Genetics, Trinity College Dublin, Dublin, Ireland
- Department of Ophthalmology, Royal Victoria Eye and Ear Hospital, Dublin, Ireland
| | - Frans P M Cremers
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
- Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, Nijmegen, The Netherlands
| | - G Jane Farrar
- The School of Genetics and Microbiology, Smurfit Institute of Genetics, Trinity College Dublin, Dublin, Ireland
| | - Susanne Roosing
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands.
- Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, Nijmegen, The Netherlands.
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10
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Biswas P, Villanueva AL, Soto-Hermida A, Duncan JL, Matsui H, Borooah S, Kurmanov B, Richard G, Khan SY, Branham K, Huang B, Suk J, Bakall B, Goldberg JL, Gabriel L, Khan NW, Raghavendra PB, Zhou J, Devalaraja S, Huynh A, Alapati A, Zawaydeh Q, Weleber RG, Heckenlively JR, Hejtmancik JF, Riazuddin S, Sieving PA, Riazuddin SA, Frazer KA, Ayyagari R. Deciphering the genetic architecture and ethnographic distribution of IRD in three ethnic populations by whole genome sequence analysis. PLoS Genet 2021; 17:e1009848. [PMID: 34662339 PMCID: PMC8589175 DOI: 10.1371/journal.pgen.1009848] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 11/12/2021] [Accepted: 09/29/2021] [Indexed: 12/12/2022] Open
Abstract
Patients with inherited retinal dystrophies (IRDs) were recruited from two understudied populations: Mexico and Pakistan as well as a third well-studied population of European Americans to define the genetic architecture of IRD by performing whole-genome sequencing (WGS). Whole-genome analysis was performed on 409 individuals from 108 unrelated pedigrees with IRDs. All patients underwent an ophthalmic evaluation to establish the retinal phenotype. Although the 108 pedigrees in this study had previously been examined for mutations in known IRD genes using a wide range of methodologies including targeted gene(s) or mutation(s) screening, linkage analysis and exome sequencing, the gene mutations responsible for IRD in these 108 pedigrees were not determined. WGS was performed on these pedigrees using Illumina X10 at a minimum of 30X depth. The sequence reads were mapped against hg19 followed by variant calling using GATK. The genome variants were annotated using SnpEff, PolyPhen2, and CADD score; the structural variants (SVs) were called using GenomeSTRiP and LUMPY. We identified potential causative sequence alterations in 61 pedigrees (57%), including 39 novel and 54 reported variants in IRD genes. For 57 of these pedigrees the observed genotype was consistent with the initial clinical diagnosis, the remaining 4 had the clinical diagnosis reclassified based on our findings. In seven pedigrees (12%) we observed atypical causal variants, i.e. unexpected genotype(s), including 4 pedigrees with causal variants in more than one IRD gene within all affected family members, one pedigree with intrafamilial genetic heterogeneity (different affected family members carrying causal variants in different IRD genes), one pedigree carrying a dominant causative variant present in pseudo-recessive form due to consanguinity and one pedigree with a de-novo variant in the affected family member. Combined atypical and large structural variants contributed to about 20% of cases. Among the novel mutations, 75% were detected in Mexican and 50% found in European American pedigrees and have not been reported in any other population while only 20% were detected in Pakistani pedigrees and were not previously reported. The remaining novel IRD causative variants were listed in gnomAD but were found to be very rare and population specific. Mutations in known IRD associated genes contributed to pathology in 63% Mexican, 60% Pakistani and 45% European American pedigrees analyzed. Overall, contribution of known IRD gene variants to disease pathology in these three populations was similar to that observed in other populations worldwide. This study revealed a spectrum of mutations contributing to IRD in three populations, identified a large proportion of novel potentially causative variants that are specific to the corresponding population or not reported in gnomAD and shed light on the genetic architecture of IRD in these diverse global populations. The study was performed to identify the underlying cause of inherited retinal degeneration (IRD) in 409 individuals from 108 families. Primarily, these families were recruited from three different geographic regions: Mexico, Pakistan and European Americans from the United States. Blood samples were collected from all individuals for genome analysis. This analysis detected causative variants in 61 out of the 108 pedigrees. A total of 93 gene variants were found in the 61 families. Among these, 54 were previously reported as causative variants and the remaining 39 have not been reported in IRD pedigrees. Interestingly, 54% of these novel variants were not listed in gnomAD. In addition to these findings, complex causative genotypes were observed in 20% of pedigrees. Overall, causative variants were detected in 63% Mexican, 60% Pakistani and 45% European American pedigrees. This study revealed the distribution of IRD causative variants in pedigrees with diverse ethnic and geographic backgrounds.
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Affiliation(s)
- Pooja Biswas
- Shiley Eye Institute, University of California San Diego, La Jolla, California, United States of America
- School of Biotechnology, REVA University, Bengaluru, Karnataka, India
| | - Adda L. Villanueva
- Retina and Genomics Institute, Yucatán, México
- Laboratoire de Diagnostic Moleculaire, Hôpital Maisonneuve Rosemont, Montreal, Quebec, Canada
| | - Angel Soto-Hermida
- Shiley Eye Institute, University of California San Diego, La Jolla, California, United States of America
| | - Jacque L. Duncan
- Ophthalmology, University of California San Francisco, San Francisco, California, United States of America
| | - Hiroko Matsui
- Institute for Genomic Medicine, University of California, San Diego, La Jolla, California, United States of America
| | - Shyamanga Borooah
- Shiley Eye Institute, University of California San Diego, La Jolla, California, United States of America
| | - Berzhan Kurmanov
- Shiley Eye Institute, University of California San Diego, La Jolla, California, United States of America
| | | | - Shahid Y. Khan
- The Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Kari Branham
- Ophthalmology & Visual Science, University of Michigan Kellogg Eye Center, Ann Arbor, Michigan, United States of America
| | - Bonnie Huang
- Shiley Eye Institute, University of California San Diego, La Jolla, California, United States of America
| | - John Suk
- Shiley Eye Institute, University of California San Diego, La Jolla, California, United States of America
| | - Benjamin Bakall
- Ophthalmology, University of Arizona College of Medicine Phoenix, Phoenix, Arizona, United States of America
| | - Jeffrey L. Goldberg
- Byers Eye Institute, Stanford, Palo Alto, California, United States of America
| | - Luis Gabriel
- Genetics and Ophthalmology, Genelabor, Goiânia, Brazil
| | - Naheed W. Khan
- Ophthalmology & Visual Science, University of Michigan Kellogg Eye Center, Ann Arbor, Michigan, United States of America
| | - Pongali B. Raghavendra
- School of Biotechnology, REVA University, Bengaluru, Karnataka, India
- School of Regenerative Medicine, Manipal University, Bengaluru, Karnataka, India
| | - Jason Zhou
- Shiley Eye Institute, University of California San Diego, La Jolla, California, United States of America
| | - Sindhu Devalaraja
- Shiley Eye Institute, University of California San Diego, La Jolla, California, United States of America
| | - Andrew Huynh
- Shiley Eye Institute, University of California San Diego, La Jolla, California, United States of America
| | - Akhila Alapati
- Shiley Eye Institute, University of California San Diego, La Jolla, California, United States of America
| | - Qais Zawaydeh
- Shiley Eye Institute, University of California San Diego, La Jolla, California, United States of America
| | - Richard G. Weleber
- Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, United States of America
| | - John R. Heckenlively
- Ophthalmology & Visual Science, University of Michigan Kellogg Eye Center, Ann Arbor, Michigan, United States of America
| | - J. Fielding Hejtmancik
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Sheikh Riazuddin
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
- Allama Iqbal Medical College, University of Health Sciences, Lahore, Pakistan
| | - Paul A. Sieving
- National Eye Institute, Bethesda, Maryland, United States of America
- Ophthalmology & Vision Science, UC Davis Medical Center, California, United States of America
| | - S. Amer Riazuddin
- The Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- * E-mail: (RA); (KAF); (SAR)
| | - Kelly A. Frazer
- Institute for Genomic Medicine, University of California, San Diego, La Jolla, California, United States of America
- Department of Pediatrics, Rady Children’s Hospital, Division of Genome Information Sciences, San Diego, California, United States of America
- * E-mail: (RA); (KAF); (SAR)
| | - Radha Ayyagari
- Shiley Eye Institute, University of California San Diego, La Jolla, California, United States of America
- * E-mail: (RA); (KAF); (SAR)
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11
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García Bohórquez B, Aller E, Rodríguez Muñoz A, Jaijo T, García García G, Millán JM. Updating the Genetic Landscape of Inherited Retinal Dystrophies. Front Cell Dev Biol 2021; 9:645600. [PMID: 34327195 PMCID: PMC8315279 DOI: 10.3389/fcell.2021.645600] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Accepted: 04/30/2021] [Indexed: 12/24/2022] Open
Abstract
Inherited retinal dystrophies (IRD) are a group of diseases characterized by the loss or dysfunction of photoreceptors and a high genetic and clinical heterogeneity. Currently, over 270 genes have been associated with IRD which makes genetic diagnosis very difficult. The recent advent of next generation sequencing has greatly facilitated the diagnostic process, enabling to provide the patients with accurate genetic counseling in some cases. We studied 92 patients who were clinically diagnosed with IRD with two different custom panels. In total, we resolved 53 patients (57.6%); in 12 patients (13%), we found only one mutation in a gene with a known autosomal recessive pattern of inheritance; and 27 patients (29.3%) remained unsolved. We identified 120 pathogenic or likely pathogenic variants; 30 of them were novel. Among the cone-rod dystrophy patients, ABCA4 was the most common mutated gene, meanwhile, USH2A was the most prevalent among the retinitis pigmentosa patients. Interestingly, 10 families carried pathogenic variants in more than one IRD gene, and we identified two deep-intronic variants previously described as pathogenic in ABCA4 and CEP290. In conclusion, the IRD study through custom panel sequencing demonstrates its efficacy for genetic diagnosis, as well as the importance of including deep-intronic regions in their design. This genetic diagnosis will allow patients to make accurate reproductive decisions, enroll in gene-based clinical trials, and benefit from future gene-based treatments.
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Affiliation(s)
- Belén García Bohórquez
- Molecular, Cellular and Genomics Biomedicine, Health Research Institute La Fe, Valencia, Spain
- CIBER of Rare Diseases, Madrid, Spain
| | - Elena Aller
- Molecular, Cellular and Genomics Biomedicine, Health Research Institute La Fe, Valencia, Spain
- CIBER of Rare Diseases, Madrid, Spain
- Unit of Genetics, University Hospital La Fe, Valencia, Spain
| | - Ana Rodríguez Muñoz
- Molecular, Cellular and Genomics Biomedicine, Health Research Institute La Fe, Valencia, Spain
- CIBER of Rare Diseases, Madrid, Spain
| | - Teresa Jaijo
- Molecular, Cellular and Genomics Biomedicine, Health Research Institute La Fe, Valencia, Spain
- CIBER of Rare Diseases, Madrid, Spain
- Unit of Genetics, University Hospital La Fe, Valencia, Spain
| | - Gema García García
- Molecular, Cellular and Genomics Biomedicine, Health Research Institute La Fe, Valencia, Spain
- CIBER of Rare Diseases, Madrid, Spain
| | - José M. Millán
- Molecular, Cellular and Genomics Biomedicine, Health Research Institute La Fe, Valencia, Spain
- CIBER of Rare Diseases, Madrid, Spain
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12
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Walker S, Lamoureux S, Khan T, Joynt ACM, Bradley M, Branson HM, Carter MT, Hayeems RZ, Jagiello L, Marshall CR, Meyn MS, Miller SP, Wilson D, Scherer SW, Blaser S, Mireskandari K, Costain G. Genome sequencing for detection of pathogenic deep intronic variation: A clinical case report illustrating opportunities and challenges. Am J Med Genet A 2021; 185:3129-3135. [PMID: 34159711 DOI: 10.1002/ajmg.a.62389] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2021] [Revised: 05/25/2021] [Accepted: 06/08/2021] [Indexed: 11/09/2022]
Abstract
Variants in JAM3 have been reported in four families manifesting a severe autosomal recessive disorder characterized by hemorrhagic destruction of the brain, subependymal calcification, and cataracts. We describe a 7-year-old male with a similar presentation found by research-based quad genome sequencing to have two novel splicing variants in trans in JAM3, including one deep intronic variant (NM_032801.4: c.256+1260G>C) not detectable by standard exome sequencing. Targeted sequencing of RNA isolated from transformed lymphoblastoid cell lines confirmed that each of the two variants has a deleterious effect on JAM3 mRNA splicing. The role for genome sequencing as a clinical diagnostic test extends to those patients with phenotypes strongly suggestive of a specific Mendelian disorder, especially when the causal genetic variant(s) are not found by a more targeted approach. Barriers to diagnosis via identification of pathogenic deep intronic variation include lack of laboratory consensus regarding in silico splicing prediction tools and limited access to clinically validated confirmatory RNA experiments.
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Affiliation(s)
- Susan Walker
- The Centre for Applied Genomics, The Hospital for Sick Children, Toronto, Ontario, Canada.,Genetics and Genome Biology, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Sylvia Lamoureux
- The Centre for Applied Genomics, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Tayyaba Khan
- Genetics and Genome Biology, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Alyssa C M Joynt
- Genetics and Genome Biology, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Melissa Bradley
- Complex Care Program, The Hospital for Sick Children and Trillium Health Partners, Greater Toronto Area, Ontario, Canada
| | - Helen M Branson
- Department of Diagnostic Imaging, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Melissa T Carter
- Department of Genetics, Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada.,Department of Pediatrics, University of Ottawa, Ottawa, Ontario, Canada
| | - Robin Z Hayeems
- Child Health Evaluative Sciences, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada.,Institute of Health Policy Management and Evaluation, University of Toronto, Toronto, Ontario, Canada
| | - Lukasz Jagiello
- Complex Care Program, The Hospital for Sick Children and Trillium Health Partners, Greater Toronto Area, Ontario, Canada
| | - Christian R Marshall
- Division of Genome Diagnostics, The Hospital for Sick Children, Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
| | - M Stephen Meyn
- Center for Human Genomics and Precision Medicine, Department of Pediatrics, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin, USA.,Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Steven P Miller
- Division of Neurology, The Hospital for Sick Children, Toronto, Ontario, Canada.,Department of Paediatrics, University of Toronto, Toronto, Ontario, Canada
| | - Diane Wilson
- Division of Neonatology, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Stephen W Scherer
- The Centre for Applied Genomics, The Hospital for Sick Children, Toronto, Ontario, Canada.,Genetics and Genome Biology, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Susan Blaser
- Department of Diagnostic Imaging, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Kamiar Mireskandari
- Department of Ophthalmology and Vision Sciences, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | - Gregory Costain
- Genetics and Genome Biology, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada.,Department of Paediatrics, University of Toronto, Toronto, Ontario, Canada.,Division of Clinical and Metabolic Genetics, The Hospital for Sick Children, Toronto, Ontario, Canada
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13
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Bowles B, Ferrer A, Nishimura CJ, Pinto E Vairo F, Rey T, Leheup B, Sullivan J, Schoch K, Stong N, Agolini E, Cocciadiferro D, Williams A, Cummings A, Loddo S, Genovese S, Roadhouse C, McWalter K, Wentzensen IM, Li C, Babovic-Vuksanovic D, Lanpher BC, Dentici ML, Ankala A, Hamm JA, Dallapiccola B, Radio FC, Shashi V, Gérard B, Bloch-Zupan A, Smith RJ, Klee EW. TSPEAR variants are primarily associated with ectodermal dysplasia and tooth agenesis but not hearing loss: A novel cohort study. Am J Med Genet A 2021; 185:2417-2433. [PMID: 34042254 PMCID: PMC8361973 DOI: 10.1002/ajmg.a.62347] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Revised: 04/12/2021] [Accepted: 04/22/2021] [Indexed: 12/30/2022]
Abstract
Biallelic loss‐of‐function variants in the thrombospondin‐type laminin G domain and epilepsy‐associated repeats (TSPEAR) gene have recently been associated with ectodermal dysplasia and hearing loss. The first reports describing a TSPEAR disease association identified this gene is a cause of nonsyndromic hearing loss, but subsequent reports involving additional affected families have questioned this evidence and suggested a stronger association with ectodermal dysplasia. To clarify genotype–phenotype associations for TSPEAR variants, we characterized 13 individuals with biallelic TSPEAR variants. Individuals underwent either exome sequencing or panel‐based genetic testing. Nearly all of these newly reported individuals (11/13) have phenotypes that include tooth agenesis or ectodermal dysplasia, while three newly reported individuals have hearing loss. Of the individuals displaying hearing loss, all have additional variants in other hearing‐loss‐associated genes, specifically TMPRSS3, GJB2, and GJB6, that present competing candidates for their hearing loss phenotype. When presented alongside previous reports, the overall evidence supports the association of TSPEAR variants with ectodermal dysplasia and tooth agenesis features but creates significant doubt as to whether TSPEAR variants are a monogenic cause of hearing loss. Further functional evidence is needed to evaluate this phenotypic association.
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Affiliation(s)
- Bradley Bowles
- Center for Individualized Medicine, Mayo Clinic, Rochester, Minnesota, USA
| | - Alejandro Ferrer
- Center for Individualized Medicine, Mayo Clinic, Rochester, Minnesota, USA
| | - Carla J Nishimura
- Molecular Otolaryngology and Renal Research Laboratories, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
| | - Filippo Pinto E Vairo
- Center for Individualized Medicine, Mayo Clinic, Rochester, Minnesota, USA.,Department of Clinical Genomics, Mayo Clinic, Rochester, Minnesota, USA
| | - Tristan Rey
- Faculté de Chirurgie Dentaire, Université de Strasbourg, Strasbourg, France.,Laboratoires de Diagnostic génétique, Pôle de Biologie, Hôpitaux Universitaires de Strasbourg, Institut de Génétique Médicale d'Alsace, Strasbourg, France.,Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U1258, CNRS-UMR7104, Université de Strasbourg, Illkirch, France
| | - Bruno Leheup
- Département de Médecine Infantile, CHRU de Nancy, Nancy, France
| | - Jennifer Sullivan
- Department of Pediatrics, Duke University, Durham, North Carolina, USA
| | - Kelly Schoch
- Department of Pediatrics, Duke University, Durham, North Carolina, USA
| | - Nicholas Stong
- Institute for Genomic Medicine, Columbia University, New York, New York, USA.,Brystol Myers Squibb, New York, New York, USA
| | - Emanuele Agolini
- Laboratory of Medical Genetics, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - Dario Cocciadiferro
- Laboratory of Medical Genetics, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - Abigail Williams
- Department of Pediatrics, East Tennessee Children's Hospital, Knoxville, Tennessee, USA
| | - Alex Cummings
- Department of Pediatrics, East Tennessee Children's Hospital, Knoxville, Tennessee, USA.,University of Wisconsin Hospitals and Clinics, Madison, Wisconsin, USA
| | - Sara Loddo
- Laboratory of Medical Genetics, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - Silvia Genovese
- Laboratory of Medical Genetics, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - Chelsea Roadhouse
- Department of Pediatrics, McMaster University, Hamilton, Ontario, Canada
| | | | | | | | - Chumei Li
- Department of Pediatrics, McMaster University, Hamilton, Ontario, Canada
| | - Dusica Babovic-Vuksanovic
- Center for Individualized Medicine, Mayo Clinic, Rochester, Minnesota, USA.,Department of Clinical Genomics, Mayo Clinic, Rochester, Minnesota, USA
| | - Brendan C Lanpher
- Center for Individualized Medicine, Mayo Clinic, Rochester, Minnesota, USA.,Department of Clinical Genomics, Mayo Clinic, Rochester, Minnesota, USA
| | - Maria Lisa Dentici
- Genetics and Rare Diseases Research Division, Molecular Genetics and Functional Genomics Research Unit, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - Arun Ankala
- EGL Genetics LLC, Tucker, Georgia, USA.,Emory University School of Medicine, Atlanta, Georgia, USA
| | - J Austin Hamm
- Department of Pediatrics, East Tennessee Children's Hospital, Knoxville, Tennessee, USA
| | - Bruno Dallapiccola
- Genetics and Rare Diseases Research Division, Molecular Genetics and Functional Genomics Research Unit, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - Francesca Clementina Radio
- Genetics and Rare Diseases Research Division, Molecular Genetics and Functional Genomics Research Unit, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - Vandana Shashi
- Department of Pediatrics, Duke University, Durham, North Carolina, USA
| | - Benedicte Gérard
- Laboratoires de Diagnostic génétique, Pôle de Biologie, Hôpitaux Universitaires de Strasbourg, Institut de Génétique Médicale d'Alsace, Strasbourg, France
| | - Agnes Bloch-Zupan
- Faculté de Chirurgie Dentaire, Université de Strasbourg, Strasbourg, France.,Centre de référence des maladies rares orales et dentaires O-Rares, Filière Santé Maladies rares TETE COU, European Reference Network CRANIO, Pôle de Médecine et Chirurgie Bucco-dentaires, Hôpital Civil, Hôpitaux Universitaires de Strasbourg (HUS), Strasbourg, France.,Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U1258, CNRS-UMR7104, Université de Strasbourg, Illkirch, France
| | - Richard J Smith
- Molecular Otolaryngology and Renal Research Laboratories, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
| | - Eric W Klee
- Center for Individualized Medicine, Mayo Clinic, Rochester, Minnesota, USA
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14
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Next-Generation Sequencing Applications for Inherited Retinal Diseases. Int J Mol Sci 2021; 22:ijms22115684. [PMID: 34073611 PMCID: PMC8198572 DOI: 10.3390/ijms22115684] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Revised: 05/21/2021] [Accepted: 05/22/2021] [Indexed: 12/12/2022] Open
Abstract
Inherited retinal diseases (IRDs) represent a collection of phenotypically and genetically diverse conditions. IRDs phenotype(s) can be isolated to the eye or can involve multiple tissues. These conditions are associated with diverse forms of inheritance, and variants within the same gene often can be associated with multiple distinct phenotypes. Such aspects of the IRDs highlight the difficulty met when establishing a genetic diagnosis in patients. Here we provide an overview of cutting-edge next-generation sequencing techniques and strategies currently in use to maximise the effectivity of IRD gene screening. These techniques have helped researchers globally to find elusive causes of IRDs, including copy number variants, structural variants, new IRD genes and deep intronic variants, among others. Resolving a genetic diagnosis with thorough testing enables a more accurate diagnosis and more informed prognosis and should also provide information on inheritance patterns which may be of particular interest to patients of a child-bearing age. Given that IRDs are heritable conditions, genetic counselling may be offered to help inform family planning, carrier testing and prenatal screening. Additionally, a verified genetic diagnosis may enable access to appropriate clinical trials or approved medications that may be available for the condition.
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15
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Orhan E, Neuillé M, de Sousa Dias M, Pugliese T, Michiels C, Condroyer C, Antonio A, Sahel JA, Audo I, Zeitz C. A New Mouse Model for Complete Congenital Stationary Night Blindness Due to Gpr179 Deficiency. Int J Mol Sci 2021; 22:ijms22094424. [PMID: 33922602 PMCID: PMC8122890 DOI: 10.3390/ijms22094424] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 04/19/2021] [Accepted: 04/20/2021] [Indexed: 01/24/2023] Open
Abstract
Mutations in GPR179 lead to autosomal recessive complete congenital stationary night blindness (cCSNB). This condition represents a signal transmission defect from the photoreceptors to the ON-bipolar cells. To confirm the phenotype, better understand the pathogenic mechanism in vivo, and provide a model for therapeutic approaches, a Gpr179 knock-out mouse model was genetically and functionally characterized. We confirmed that the insertion of a neo/lac Z cassette in intron 1 of Gpr179 disrupts the same gene. Spectral domain optical coherence tomography reveals no obvious retinal structure abnormalities. Gpr179 knock-out mice exhibit a so-called no-b-wave (nob) phenotype with severely reduced b-wave amplitudes in the electroretinogram. Optomotor tests reveal decreased optomotor responses under scotopic conditions. Consistent with the genetic disruption of Gpr179, GPR179 is absent at the dendritic tips of ON-bipolar cells. While proteins of the same signal transmission cascade (GRM6, LRIT3, and TRPM1) are correctly localized, other proteins (RGS7, RGS11, and GNB5) known to regulate GRM6 are absent at the dendritic tips of ON-bipolar cells. These results add a new model of cCSNB, which is important to better understand the role of GPR179, its implication in patients with cCSNB, and its use for the development of therapies.
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Affiliation(s)
- Elise Orhan
- Institut de la Vision, Institut National de la Santé et de la Recherche Médicale, Centre National de la Recherche Scientifique, Sorbonne Université, F-75012 Paris, France; (E.O.); (M.N.); (M.d.S.D.); (T.P.); (C.M.); (C.C.); (A.A.); (J.-A.S.); (I.A.)
| | - Marion Neuillé
- Institut de la Vision, Institut National de la Santé et de la Recherche Médicale, Centre National de la Recherche Scientifique, Sorbonne Université, F-75012 Paris, France; (E.O.); (M.N.); (M.d.S.D.); (T.P.); (C.M.); (C.C.); (A.A.); (J.-A.S.); (I.A.)
| | - Miguel de Sousa Dias
- Institut de la Vision, Institut National de la Santé et de la Recherche Médicale, Centre National de la Recherche Scientifique, Sorbonne Université, F-75012 Paris, France; (E.O.); (M.N.); (M.d.S.D.); (T.P.); (C.M.); (C.C.); (A.A.); (J.-A.S.); (I.A.)
| | - Thomas Pugliese
- Institut de la Vision, Institut National de la Santé et de la Recherche Médicale, Centre National de la Recherche Scientifique, Sorbonne Université, F-75012 Paris, France; (E.O.); (M.N.); (M.d.S.D.); (T.P.); (C.M.); (C.C.); (A.A.); (J.-A.S.); (I.A.)
| | - Christelle Michiels
- Institut de la Vision, Institut National de la Santé et de la Recherche Médicale, Centre National de la Recherche Scientifique, Sorbonne Université, F-75012 Paris, France; (E.O.); (M.N.); (M.d.S.D.); (T.P.); (C.M.); (C.C.); (A.A.); (J.-A.S.); (I.A.)
| | - Christel Condroyer
- Institut de la Vision, Institut National de la Santé et de la Recherche Médicale, Centre National de la Recherche Scientifique, Sorbonne Université, F-75012 Paris, France; (E.O.); (M.N.); (M.d.S.D.); (T.P.); (C.M.); (C.C.); (A.A.); (J.-A.S.); (I.A.)
| | - Aline Antonio
- Institut de la Vision, Institut National de la Santé et de la Recherche Médicale, Centre National de la Recherche Scientifique, Sorbonne Université, F-75012 Paris, France; (E.O.); (M.N.); (M.d.S.D.); (T.P.); (C.M.); (C.C.); (A.A.); (J.-A.S.); (I.A.)
| | - José-Alain Sahel
- Institut de la Vision, Institut National de la Santé et de la Recherche Médicale, Centre National de la Recherche Scientifique, Sorbonne Université, F-75012 Paris, France; (E.O.); (M.N.); (M.d.S.D.); (T.P.); (C.M.); (C.C.); (A.A.); (J.-A.S.); (I.A.)
- Centre Hospitalier National d’Ophtalmologie des Quinze-Vingts, INSERM-DGOS CIC1423, F-75012 Paris, France
- Fondation Ophtalmologique Adolphe de Rothschild, F-75019 Paris, France
- Academie des Sciences, Institut de France, F-75006 Paris, France
- Department of Ophthalmology, The University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
| | - Isabelle Audo
- Institut de la Vision, Institut National de la Santé et de la Recherche Médicale, Centre National de la Recherche Scientifique, Sorbonne Université, F-75012 Paris, France; (E.O.); (M.N.); (M.d.S.D.); (T.P.); (C.M.); (C.C.); (A.A.); (J.-A.S.); (I.A.)
- Centre Hospitalier National d’Ophtalmologie des Quinze-Vingts, INSERM-DGOS CIC1423, F-75012 Paris, France
- Institute of Ophthalmology, University College of London, London EC1V 9EL, UK
| | - Christina Zeitz
- Institut de la Vision, Institut National de la Santé et de la Recherche Médicale, Centre National de la Recherche Scientifique, Sorbonne Université, F-75012 Paris, France; (E.O.); (M.N.); (M.d.S.D.); (T.P.); (C.M.); (C.C.); (A.A.); (J.-A.S.); (I.A.)
- Correspondence: ; Tel.: +33-1-53-46-25-40
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16
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Bolz HJ. Diagnostic Analyses of Retinal Dystrophy Genes: Current Status and Perspective. Klin Monbl Augenheilkd 2021; 238:261-266. [PMID: 33784789 DOI: 10.1055/a-1386-5361] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Over the past decade, novel high-throughput DNA sequencing technologies have revolutionised both research and diagnostic testing for monogenic disorders. This applies particularly to genetically very heterogeneous disorders like retinal dystrophies (RDs). Next-generation sequencing (NGS) today is considered as reliable as Sanger sequencing, which had been the gold standard for decades. Today, comprehensive NGS-based diagnostic testing reveals the causative mutations in the majority of RD patients, with important implications for genetic counselling for recurrence risks and personalised medical management (from interdisciplinary surveillance to prophylactic measures and, albeit yet rare, [gene] therapy). While DNA sequencing is - in most cases - no longer the diagnostic bottleneck, one needs to be aware of interpretation pitfalls and dead ends. The advent of new (NGS) technologies will solve some of these issues. However, specialised medical geneticists who are familiar with the peculiarities of certain RD genes and closely interact with ophthalmologists will remain key to successful RD research and diagnostic testing for the benefit of the patients. This review sheds light on the current state of the field, its challenges and potential solutions.
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Affiliation(s)
- Hanno Jörn Bolz
- Humangenetik, Senckenberg Zentrum für Humangenetik, Frankfurt, Germany.,Humangenetik, University Hospital of Cologne, Cologne, Germany
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17
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Kortüm F, Kieninger S, Mazzola P, Kohl S, Wissinger B, Prokisch H, Stingl K, Weisschuh N. X-Linked Retinitis Pigmentosa Caused by Non-Canonical Splice Site Variants in RPGR. Int J Mol Sci 2021; 22:ijms22020850. [PMID: 33467000 PMCID: PMC7830253 DOI: 10.3390/ijms22020850] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 01/14/2021] [Accepted: 01/14/2021] [Indexed: 01/13/2023] Open
Abstract
We aimed to validate the effect of non-canonical splice site variants in the RPGR gene in five patients from four families diagnosed with retinitis pigmentosa. Four variants located in intron 2 (c.154 + 3_154 + 6del), intron 3 (c.247 + 5G>A), intron 7 (c.779-5T>G), and intron 13 (c.1573-12A>G), respectively, were analyzed by means of in vitro splice assays. Splicing analysis revealed different aberrant splicing events, including exon skipping and intronic nucleotide addition, which are predicted to lead either to an in-frame deletion affecting relevant protein domains or to a frameshift of the open reading frame. Our data expand the landscape of pathogenic variants in RPGR, thereby increasing the genetic diagnostic rate in retinitis pigmentosa and allowing patients harboring the analyzed variants to be enrolled in clinical trials.
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Affiliation(s)
- Friederike Kortüm
- Center for Ophthalmology, University Eye Hospital, University of Tübingen, 72076 Tübingen, Germany; (F.K.); (K.S.)
| | - Sinja Kieninger
- Center for Ophthalmology, Institute for Ophthalmic Research, University of Tübingen, 72076 Tübingen, Germany; (S.K.); (S.K.); (B.W.)
| | - Pascale Mazzola
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, 72076 Tübingen, Germany;
| | - Susanne Kohl
- Center for Ophthalmology, Institute for Ophthalmic Research, University of Tübingen, 72076 Tübingen, Germany; (S.K.); (S.K.); (B.W.)
| | - Bernd Wissinger
- Center for Ophthalmology, Institute for Ophthalmic Research, University of Tübingen, 72076 Tübingen, Germany; (S.K.); (S.K.); (B.W.)
| | - Holger Prokisch
- Institute of Neurogenomics, Helmholtz Zentrum München, 85764 Neuherberg, Germany;
- Institute of Human Genetics, Technische Universität München, 81675 Munich, Germany
| | - Katarina Stingl
- Center for Ophthalmology, University Eye Hospital, University of Tübingen, 72076 Tübingen, Germany; (F.K.); (K.S.)
| | - Nicole Weisschuh
- Center for Ophthalmology, Institute for Ophthalmic Research, University of Tübingen, 72076 Tübingen, Germany; (S.K.); (S.K.); (B.W.)
- Correspondence:
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18
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Ki CS. Recent Advances in the Clinical Application of Next-Generation Sequencing. Pediatr Gastroenterol Hepatol Nutr 2021; 24:1-6. [PMID: 33505888 PMCID: PMC7813577 DOI: 10.5223/pghn.2021.24.1.1] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Accepted: 12/08/2020] [Indexed: 02/06/2023] Open
Abstract
Next-generation sequencing (NGS) technologies have changed the process of genetic diagnosis from a gene-by-gene approach to syndrome-based diagnostic gene panel sequencing (DPS), diagnostic exome sequencing (DES), and diagnostic genome sequencing (DGS). A priori information on the causative genes that might underlie a genetic condition is a prerequisite for genetic diagnosis before conducting clinical NGS tests. Theoretically, DPS, DES, and DGS do not require any information on specific candidate genes. Therefore, clinical NGS tests sometimes detect disease-related pathogenic variants in genes underlying different conditions from the initial diagnosis. These clinical NGS tests are expensive, but they can be a cost-effective approach for the rapid diagnosis of rare disorders with genetic heterogeneity, such as the glycogen storage disease, familial intrahepatic cholestasis, lysosomal storage disease, and primary immunodeficiency. In addition, DES or DGS may find novel genes that that were previously not linked to human diseases.
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