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Abstract
The limb-girdle muscular dystrophies (LGMD) are a collection of genetic diseases united in their phenotypical expression of pelvic and shoulder area weakness and wasting. More than 30 subtypes have been identified, five dominant and 26 recessive. The increase in the characterization of new genotypes in the family of LGMDs further adds to the heterogeneity of the disease. Meanwhile, better understanding of the phenotype led to the reconsideration of the disease definition, which resulted in eight old subtypes to be no longer recognized officially as LGMD and five new diseases to be added to the LGMD family. The unique variabilities of LGMD stem from genetic mutations, which then lead to protein and ultimately muscle dysfunction. Herein, we review the LGMD pathway, starting with the genetic mutations that encode proteins involved in muscle maintenance and repair, and including the genotype–phenotype relationship of the disease, the epidemiology, disease progression, burden of illness, and emerging treatments.
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52
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Abstract
PURPOSE OF REVIEW The last few years have confirmed previous assumptions of an enormous impact of the titin gene (TTN) on the occurrence of muscle disease, cardiomyopathy, or both together. The reason for this rather late understanding of its importance is because of the huge size which prevented sequencing of the whole gene by the previous Sanger technique in the individual cases. An update of the advances in diagnosing titinopathies is the main focus of this review. RECENT FINDINGS High throughput methods are now widely available for TTN sequencing and a corresponding explosion of different types of identified titinopathies is observed and published in the literature, although final confirmation is lacking in many cases with recessive missense variants. SUMMARY The implications of these findings for clinical practice are easy to understand: patients with previously undiagnosed muscle disease can now have a correct diagnosis and subsequently receive a likely prognosis, can have accurate genetic counseling for the whole family and early treatment for predictable complications from the heart and respiratory muscles. In addition not to forget, they can avoid wrong diagnoses leading to wrong treatments.
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53
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Peddareddygari LR, Baisre-de León A, Grewal RP. Genotype phenotype analysis in a family carrying truncating mutations in the titin gene. ACTA MYOLOGICA : MYOPATHIES AND CARDIOMYOPATHIES : OFFICIAL JOURNAL OF THE MEDITERRANEAN SOCIETY OF MYOLOGY 2021; 40:61-65. [PMID: 33870097 PMCID: PMC8033428 DOI: 10.36185/2532-1900-043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Accepted: 03/04/2021] [Indexed: 11/15/2022]
Abstract
We report a family carrying a previously described truncating mutation, NM_001267550.2(TTN):c.107889del p.(Lys35963Asnfs*9) in exon 364, and a novel truncating mutation, NM_001267550.1:c.100704C > A p.(Tyr33568*) in exon 358 in the titin gene. The c.107889del mutation, which was maternally transmitted, has been previously described in patients from the Iberian Peninsula. The mother was of Peruvian descent suggesting a potential European ancestral origin of this mutation. In this family, a daughter, who is a compound heterozygote carrying both these mutations, developed a peripartum cardiomyopathy during her second pregnancy. Subsequently, she was diagnosed with a myopathy following electromyography testing and a muscle biopsy which showed fiber type disproportion. Her brother, who carries only the paternally inherited c.100704C > A mutation, developed a cardiomyopathy following a suspected viral illness. Their father, who transmitted this mutation, has no evidence of a cardiomyopathy. We hypothesize that the c.100704C > A mutation confers susceptibility to the development of cardiomyopathy which may be brought on by cardiovascular stress. Our study of this family expands the genotype and phenotype spectrum of disorders that can be associated with mutations in the titin gene.
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Affiliation(s)
| | - Ada Baisre-de León
- Department of Pathology, Immunology & Laboratory Medicine, Rutgers-New Jersey medical School, Newark, New Jersey, USA
| | - Raji P Grewal
- Dynamic Biologics Inc., Monmouth Junction, New Jersey, USA.,Neuroscience Institute, Saint Francis Medical Center, Trenton, New Jersey, USA
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54
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Savarese M, Välipakka S, Johari M, Hackman P, Udd B. Is Gene-Size an Issue for the Diagnosis of Skeletal Muscle Disorders? J Neuromuscul Dis 2021; 7:203-216. [PMID: 32176652 PMCID: PMC7369045 DOI: 10.3233/jnd-190459] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Human genes have a variable length. Those having a coding sequence of extraordinary length and a high number of exons were almost impossible to sequence using the traditional Sanger-based gene-by-gene approach. High-throughput sequencing has partly overcome the size-related technical issues, enabling a straightforward, rapid and relatively inexpensive analysis of large genes. Several large genes (e.g. TTN, NEB, RYR1, DMD) are recognized as disease-causing in patients with skeletal muscle diseases. However, because of their sheer size, the clinical interpretation of variants in these genes is probably the most challenging aspect of the high-throughput genetic investigation in the field of skeletal muscle diseases. The main aim of this review is to discuss the technical and interpretative issues related to the diagnostic investigation of large genes and to reflect upon the current state of the art and the future advancements in the field.
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Affiliation(s)
- Marco Savarese
- Folkhälsan Research Center, Helsinki, Finland.,Department of Medical Genetics, Medicum, University of Helsinki, Helsinki, Finland
| | - Salla Välipakka
- Folkhälsan Research Center, Helsinki, Finland.,Department of Medical Genetics, Medicum, University of Helsinki, Helsinki, Finland
| | - Mridul Johari
- Folkhälsan Research Center, Helsinki, Finland.,Department of Medical Genetics, Medicum, University of Helsinki, Helsinki, Finland
| | - Peter Hackman
- Folkhälsan Research Center, Helsinki, Finland.,Department of Medical Genetics, Medicum, University of Helsinki, Helsinki, Finland
| | - Bjarne Udd
- Folkhälsan Research Center, Helsinki, Finland.,Department of Medical Genetics, Medicum, University of Helsinki, Helsinki, Finland.,Neuromuscular Research Center, Tampere University and University Hospital, Tampere, Finland.,Department of Neurology, Vaasa Central Hospital, Vaasa, Finland
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55
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Rees M, Nikoopour R, Fukuzawa A, Kho AL, Fernandez-Garcia MA, Wraige E, Bodi I, Deshpande C, Özdemir Ö, Daimagüler HS, Pfuhl M, Holt M, Brandmeier B, Grover S, Fluss J, Longman C, Farrugia ME, Matthews E, Hanna M, Muntoni F, Sarkozy A, Phadke R, Quinlivan R, Oates EC, Schröder R, Thiel C, Reimann J, Voermans N, Erasmus C, Kamsteeg EJ, Konersman C, Grosmann C, McKee S, Tirupathi S, Moore SA, Wilichowski E, Hobbiebrunken E, Dekomien G, Richard I, Van den Bergh P, Domínguez-González C, Cirak S, Ferreiro A, Jungbluth H, Gautel M. Making sense of missense variants in TTN-related congenital myopathies. Acta Neuropathol 2021; 141:431-453. [PMID: 33449170 PMCID: PMC7882473 DOI: 10.1007/s00401-020-02257-0] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 12/20/2020] [Accepted: 12/20/2020] [Indexed: 12/15/2022]
Abstract
Mutations in the sarcomeric protein titin, encoded by TTN, are emerging as a common cause of myopathies. The diagnosis of a TTN-related myopathy is, however, often not straightforward due to clinico-pathological overlap with other myopathies and the prevalence of TTN variants in control populations. Here, we present a combined clinico-pathological, genetic and biophysical approach to the diagnosis of TTN-related myopathies and the pathogenicity ascertainment of TTN missense variants. We identified 30 patients with a primary TTN-related congenital myopathy (CM) and two truncating variants, or one truncating and one missense TTN variant, or homozygous for one TTN missense variant. We found that TTN-related myopathies show considerable overlap with other myopathies but are strongly suggested by a combination of certain clinico-pathological features. Presentation was typically at birth with the clinical course characterized by variable progression of weakness, contractures, scoliosis and respiratory symptoms but sparing of extraocular muscles. Cardiac involvement depended on the variant position. Our biophysical analyses demonstrated that missense mutations associated with CMs are strongly destabilizing and exert their effect when expressed on a truncating background or in homozygosity. We hypothesise that destabilizing TTN missense mutations phenocopy truncating variants and are a key pathogenic feature of recessive titinopathies that might be amenable to therapeutic intervention.
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Affiliation(s)
- Martin Rees
- Randall Centre for Cell and Molecular Biophysics, Muscle Biophysics, King's College London BHF Centre of Research Excellence, London, UK
| | - Roksana Nikoopour
- Randall Centre for Cell and Molecular Biophysics, Muscle Biophysics, King's College London BHF Centre of Research Excellence, London, UK
| | - Atsushi Fukuzawa
- Randall Centre for Cell and Molecular Biophysics, Muscle Biophysics, King's College London BHF Centre of Research Excellence, London, UK
| | - Ay Lin Kho
- Randall Centre for Cell and Molecular Biophysics, Muscle Biophysics, King's College London BHF Centre of Research Excellence, London, UK
| | - Miguel A Fernandez-Garcia
- Department of Paediatric Neurology, Evelina Children's Hospital, Guy's & St Thomas' NHS Foundation Trust, London, UK
| | - Elizabeth Wraige
- Department of Paediatric Neurology, Evelina Children's Hospital, Guy's & St Thomas' NHS Foundation Trust, London, UK
| | - Istvan Bodi
- Department of Clinical Neuropathology, King's College Hospital, London, UK
| | | | - Özkan Özdemir
- Centre for Molecular Medicine, University of Cologne, Cologne, Germany
- Department of Pediatrics, University Hospital Cologne and Faculty of Medicine, University of Cologne, Cologne, Germany
| | - Hülya-Sevcan Daimagüler
- Centre for Molecular Medicine, University of Cologne, Cologne, Germany
- Department of Pediatrics, University Hospital Cologne and Faculty of Medicine, University of Cologne, Cologne, Germany
| | - Mark Pfuhl
- Randall Centre for Cell and Molecular Biophysics, Muscle Biophysics, King's College London BHF Centre of Research Excellence, London, UK
- School of Cardiovascular Medicine and Sciences, King's College London BHF Centre of Research Excellence, London, UK
| | - Mark Holt
- Randall Centre for Cell and Molecular Biophysics, Muscle Biophysics, King's College London BHF Centre of Research Excellence, London, UK
- School of Cardiovascular Medicine and Sciences, King's College London BHF Centre of Research Excellence, London, UK
| | - Birgit Brandmeier
- Randall Centre for Cell and Molecular Biophysics, Muscle Biophysics, King's College London BHF Centre of Research Excellence, London, UK
| | - Sarah Grover
- Randall Centre for Cell and Molecular Biophysics, Muscle Biophysics, King's College London BHF Centre of Research Excellence, London, UK
| | - Joël Fluss
- Pediatric Neurology Unit, Paediatrics Subspecialties Service, Geneva Children's Hospital, Geneva, Switzerland
| | - Cheryl Longman
- West of Scotland Regional Genetics Service, Laboratory Medicine Building, Queen Elizabeth University Hospital, Glasgow, UK
| | | | - Emma Matthews
- MRC Neuromuscular Centre, National Hospital for Neurology and Neurosurgery, Queen's Square, London, UK
| | - Michael Hanna
- MRC Neuromuscular Centre, National Hospital for Neurology and Neurosurgery, Queen's Square, London, UK
| | - Francesco Muntoni
- Dubowitz Neuromuscular Centre, Great Ormond Street Hospital for Children, London, UK
- NIHR Great Ormond Street Hospital Biomedical Research Centre, Great Ormond Street Institute of Child Health, University College London, Great Ormond Street Hospital Trust, London, UK
| | - Anna Sarkozy
- Dubowitz Neuromuscular Centre, Great Ormond Street Hospital for Children, London, UK
| | - Rahul Phadke
- Dubowitz Neuromuscular Centre, Great Ormond Street Hospital for Children, London, UK
| | - Ros Quinlivan
- Dubowitz Neuromuscular Centre, Great Ormond Street Hospital for Children, London, UK
| | - Emily C Oates
- Dubowitz Neuromuscular Centre, Great Ormond Street Hospital for Children, London, UK
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sidney, Australia
- Kids Neuroscience Centre, Kids Research, The Children's Hospital at Westmead, Sydney, NSW, Australia
| | - Rolf Schröder
- Institute of Neuropathology, University Hospital Erlangen, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Christian Thiel
- Department of Genetics, University of Erlangen, Erlangen, Germany
| | - Jens Reimann
- Muscle Laboratory, Department of Neurology, University of Bonn Medical Centre, Bonn, Germany
| | - Nicol Voermans
- Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen, The Netherlands
| | - Corrie Erasmus
- Department of Paediatric Neurology, Radboud University, Nijmegen, The Netherlands
| | - Erik-Jan Kamsteeg
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Chaminda Konersman
- UCSD, Rady Children's Hospital, and VA San Diego Healthcare System, San Diego, USA
| | | | - Shane McKee
- Northern Ireland Regional Genetics Service, Belfast City Hospital, Belfast, UK
| | - Sandya Tirupathi
- Department of Paediatric Neurology, Royal Belfast Hospital for Sick Children, Belfast, UK
| | - Steven A Moore
- Department of Pathology, The University of Iowa, Iowa City, IA, USA
| | | | - Elke Hobbiebrunken
- Department of Paediatric Neurology, University of Göttingen, Göttingen, Germany
| | | | - Isabelle Richard
- Genethon and UMR_S951, INSERM, Université Evry, Université Paris Saclay, Evry, 91002, Evry, France
| | - Peter Van den Bergh
- Neuromuscular Reference Centre, Department of Neurology, University Hospital Saint-Luc, Brussels, Belgium
| | | | - Sebahattin Cirak
- Centre for Molecular Medicine, University of Cologne, Cologne, Germany
- Department of Pediatrics, University Hospital Cologne and Faculty of Medicine, University of Cologne, Cologne, Germany
- Centre for Rare Diseases (ZSEK), University of Cologne, Cologne, Germany
| | - Ana Ferreiro
- Basic and Translational Myology Laboratory, Université de Paris, Paris, France
- Centre de Référence Des Maladies Neuromusculaires, APHP, Institut of Myology, GHU Pitié Salpêtrière- Charles Foix, Paris, France
| | - Heinz Jungbluth
- Randall Centre for Cell and Molecular Biophysics, Muscle Biophysics, King's College London BHF Centre of Research Excellence, London, UK
- Department of Paediatric Neurology, Evelina Children's Hospital, Guy's & St Thomas' NHS Foundation Trust, London, UK
- Department of Clinical and Basic Neuroscience, IoPPN, King's College London, London, UK
| | - Mathias Gautel
- Randall Centre for Cell and Molecular Biophysics, Muscle Biophysics, King's College London BHF Centre of Research Excellence, London, UK.
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56
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Lopez-Bravo A, Roche-Bueno JC, Romera-López A, Larrode-Pellicer P. A novel TTN variant in a patient with distal myopathy of lower limbs and dilated cardiomyopathy. Neurologia 2021; 36:S0213-4853(21)00004-9. [PMID: 33558083 DOI: 10.1016/j.nrl.2021.01.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 12/26/2020] [Accepted: 01/10/2021] [Indexed: 10/22/2022] Open
Affiliation(s)
- A Lopez-Bravo
- Sección de Neurología, Hospital Reina Sofía, Tudela, Navarra, España; Instituto de Investigación Sanitaria Aragón (IIS-A), España.
| | - J C Roche-Bueno
- Servicio de Neurología, Hospital Clínico Universitario Lozano Blesa, Zaragoza, España
| | - A Romera-López
- Unidad de Genética Médica, Sistemas Genómicos, Valencia, España
| | - P Larrode-Pellicer
- Servicio de Neurología, Hospital Clínico Universitario Lozano Blesa, Zaragoza, España
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57
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Plasma membrane integrity in health and disease: significance and therapeutic potential. Cell Discov 2021; 7:4. [PMID: 33462191 PMCID: PMC7813858 DOI: 10.1038/s41421-020-00233-2] [Citation(s) in RCA: 88] [Impact Index Per Article: 29.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Accepted: 10/23/2020] [Indexed: 12/13/2022] Open
Abstract
Maintenance of plasma membrane integrity is essential for normal cell viability and function. Thus, robust membrane repair mechanisms have evolved to counteract the eminent threat of a torn plasma membrane. Different repair mechanisms and the bio-physical parameters required for efficient repair are now emerging from different research groups. However, less is known about when these mechanisms come into play. This review focuses on the existence of membrane disruptions and repair mechanisms in both physiological and pathological conditions, and across multiple cell types, albeit to different degrees. Fundamentally, irrespective of the source of membrane disruption, aberrant calcium influx is the common stimulus that activates the membrane repair response. Inadequate repair responses can tip the balance between physiology and pathology, highlighting the significance of plasma membrane integrity. For example, an over-activated repair response can promote cancer invasion, while the inability to efficiently repair membrane can drive neurodegeneration and muscular dystrophies. The interdisciplinary view explored here emphasises the widespread potential of targeting plasma membrane repair mechanisms for therapeutic purposes.
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58
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Savarese M, Sarparanta J, Vihola A, Jonson PH, Johari M, Rusanen S, Hackman P, Udd B. Panorama of the distal myopathies. ACTA MYOLOGICA : MYOPATHIES AND CARDIOMYOPATHIES : OFFICIAL JOURNAL OF THE MEDITERRANEAN SOCIETY OF MYOLOGY 2020; 39:245-265. [PMID: 33458580 PMCID: PMC7783427 DOI: 10.36185/2532-1900-028] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Accepted: 11/11/2020] [Indexed: 12/15/2022]
Abstract
Distal myopathies are genetic primary muscle disorders with a prominent weakness at onset in hands and/or feet. The age of onset (from early childhood to adulthood), the distribution of muscle weakness (upper versus lower limbs) and the histological findings (ranging from nonspecific myopathic changes to myofibrillar disarrays and rimmed vacuoles) are extremely variable. However, despite being characterized by a wide clinical and genetic heterogeneity, the distal myopathies are a category of muscular dystrophies: genetic diseases with progressive loss of muscle fibers. Myopathic congenital arthrogryposis is also a form of distal myopathy usually caused by focal amyoplasia. Massive parallel sequencing has further expanded the long list of genes associated with a distal myopathy, and contributed identifying as distal myopathy-causative rare variants in genes more often related with other skeletal or cardiac muscle diseases. Currently, almost 20 genes (ACTN2, CAV3, CRYAB, DNAJB6, DNM2, FLNC, HNRNPA1, HSPB8, KHLH9, LDB3, MATR3, MB, MYOT, PLIN4, TIA1, VCP, NOTCH2NLC, LRP12, GIPS1) have been associated with an autosomal dominant form of distal myopathy. Pathogenic changes in four genes (ADSSL, ANO5, DYSF, GNE) cause an autosomal recessive form; and disease-causing variants in five genes (DES, MYH7, NEB, RYR1 and TTN) result either in a dominant or in a recessive distal myopathy. Finally, a digenic mechanism, underlying a Welander-like form of distal myopathy, has been recently elucidated. Rare pathogenic mutations in SQSTM1, previously identified with a bone disease (Paget disease), unexpectedly cause a distal myopathy when combined with a common polymorphism in TIA1. The present review aims at describing the genetic basis of distal myopathy and at summarizing the clinical features of the different forms described so far.
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Affiliation(s)
- Marco Savarese
- Folkhälsan Research Center, Helsinki, Finland
- Department of Medical Genetics, Medicum, University of Helsinki, Helsinki, Finland
| | - Jaakko Sarparanta
- Folkhälsan Research Center, Helsinki, Finland
- Department of Medical Genetics, Medicum, University of Helsinki, Helsinki, Finland
| | - Anna Vihola
- Folkhälsan Research Center, Helsinki, Finland
- Department of Medical Genetics, Medicum, University of Helsinki, Helsinki, Finland
- Neuromuscular Research Center, Department of Genetics, Fimlab Laboratories, Tampere, Finland
| | - Per Harald Jonson
- Folkhälsan Research Center, Helsinki, Finland
- Department of Medical Genetics, Medicum, University of Helsinki, Helsinki, Finland
| | - Mridul Johari
- Folkhälsan Research Center, Helsinki, Finland
- Department of Medical Genetics, Medicum, University of Helsinki, Helsinki, Finland
| | - Salla Rusanen
- Folkhälsan Research Center, Helsinki, Finland
- Department of Medical Genetics, Medicum, University of Helsinki, Helsinki, Finland
| | - Peter Hackman
- Folkhälsan Research Center, Helsinki, Finland
- Department of Medical Genetics, Medicum, University of Helsinki, Helsinki, Finland
| | - Bjarne Udd
- Folkhälsan Research Center, Helsinki, Finland
- Department of Medical Genetics, Medicum, University of Helsinki, Helsinki, Finland
- Department of Neurology, Vaasa Central Hospital, Vaasa, Finland
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59
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Savarese M, Johari M, Johnson K, Arumilli M, Torella A, Töpf A, Rubegni A, Kuhn M, Giugliano T, Gläser D, Fattori F, Thompson R, Penttilä S, Lehtinen S, Gibertini S, Ruggieri A, Mora M, Maver A, Peterlin B, Mankodi A, Lochmüller H, Santorelli FM, Schoser B, Fajkusová L, Straub V, Nigro V, Hackman P, Udd B. Improved Criteria for the Classification of Titin Variants in Inherited Skeletal Myopathies. J Neuromuscul Dis 2020; 7:153-166. [PMID: 32039858 DOI: 10.3233/jnd-190423] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
BACKGROUND Extensive genetic screening results in the identification of thousands of rare variants that are difficult to interpret. Because of its sheer size, rare variants in the titin gene (TTN) are detected frequently in any individual. Unambiguous interpretation of molecular findings is almost impossible in many patients with myopathies or cardiomyopathies. OBJECTIVE To refine the current classification framework for TTN-associated skeletal muscle disorders and standardize the interpretation of TTN variants. METHODS We used the guidelines issued by the American College of Medical Genetics and Genomics (ACMG) and the Association for Molecular Pathology (AMP) to re-analyze TTN genetic findings from our patient cohort. RESULTS We identified in the classification guidelines three rules that are not applicable to titin-related skeletal muscle disorders; six rules that require disease-/gene-specific adjustments and four rules requiring quantitative thresholds for a proper use. In three cases, the rule strength need to be modified. CONCLUSIONS We suggest adjustments are made to the guidelines. We provide frequency thresholds to facilitate filtering of candidate causative variants and guidance for the use and interpretation of functional data and co-segregation evidence. We expect that the variant classification framework for TTN-related skeletal muscle disorders will be further improved along with a better understanding of these diseases.
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Affiliation(s)
- Marco Savarese
- Folkhälsan Research Center, Helsinki, Finland.,Department of Medical Genetics, Medicum, University of Helsinki, Helsinki, Finland
| | - Mridul Johari
- Folkhälsan Research Center, Helsinki, Finland.,Department of Medical Genetics, Medicum, University of Helsinki, Helsinki, Finland
| | - Katherine Johnson
- The John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
| | - Meharji Arumilli
- Folkhälsan Research Center, Helsinki, Finland.,Department of Medical Genetics, Medicum, University of Helsinki, Helsinki, Finland
| | - Annalaura Torella
- Dipartimento di Medicina di Precisione, Universitá degli Studi della Campania "Luigi Vanvitelli", Naples, Italy.,Telethon Institute of Genetics and Medicine, Pozzuoli, Italy
| | - Ana Töpf
- The John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
| | | | | | - Teresa Giugliano
- Dipartimento di Medicina di Precisione, Universitá degli Studi della Campania "Luigi Vanvitelli", Naples, Italy.,Telethon Institute of Genetics and Medicine, Pozzuoli, Italy
| | | | - Fabiana Fattori
- Unit for Neuromuscular and Neurodegenerative Disorders, Bambino Gesù Children's Hospital, Rome, Italy
| | - Rachel Thompson
- The John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
| | - Sini Penttilä
- Neuromuscular Research Center, Department of Genetics, Fimlab Laboratories, Tampere, Finland
| | - Sara Lehtinen
- Neuromuscular Research Center, Department of Genetics, Fimlab Laboratories, Tampere, Finland
| | - Sara Gibertini
- Neuromuscular Diseases and Neuroimmunology Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milano, Italy
| | - Alessandra Ruggieri
- Neuromuscular Diseases and Neuroimmunology Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milano, Italy.,Department of Molecular and Translation Medicine, Unit of Biology and Genetics, University of Brescia, Brescia, Italy
| | - Marina Mora
- Neuromuscular Diseases and Neuroimmunology Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milano, Italy
| | - Ales Maver
- Clinical Institute of Medical Genetics, University Medical Centre Ljubljana, Ljubljana, Slovenia
| | - Borut Peterlin
- Clinical Institute of Medical Genetics, University Medical Centre Ljubljana, Ljubljana, Slovenia
| | - Ami Mankodi
- Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, Unites States
| | - Hanns Lochmüller
- Department of Neuropediatrics and Muscle Disorders, Medical Center - University of Freiburg, Faculty of Medicine, Freiburg, Germany.,Centro Nacional de Análisis Genómico (CNAG-CRG), Center for Genomic Regulation, Barcelona Institute of Science and Technology (BIST), Barcelona, Spain.,Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, Canada.,Division of Neurology, Department of Medicine, The Ottawa Hospital, Ottawa, Canada
| | | | - Benedikt Schoser
- Friedrich-Baur-Institut, Neurologische Klinik Ludwig-Maximilians-Universität München, Munich, Germany
| | - Lenka Fajkusová
- Centre of Molecular Biology and Gene Therapy, University Hospital Brno and Masaryk University Brno, Brno, Czech Republic
| | - Volker Straub
- The John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
| | - Vincenzo Nigro
- Dipartimento di Medicina di Precisione, Universitá degli Studi della Campania "Luigi Vanvitelli", Naples, Italy.,Telethon Institute of Genetics and Medicine, Pozzuoli, Italy
| | - Peter Hackman
- Folkhälsan Research Center, Helsinki, Finland.,Department of Medical Genetics, Medicum, University of Helsinki, Helsinki, Finland
| | - Bjarne Udd
- Folkhälsan Research Center, Helsinki, Finland.,Department of Medical Genetics, Medicum, University of Helsinki, Helsinki, Finland.,Department of Neurology, Vaasa Central Hospital, Vaasa, Finland.,Neuromuscular Research Center, Tampere University and University Hospital, Tampere, Finland
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60
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The importance of an integrated genotype-phenotype strategy to unravel the molecular bases of titinopathies. Neuromuscul Disord 2020; 30:877-887. [PMID: 33127292 DOI: 10.1016/j.nmd.2020.09.032] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 08/26/2020] [Accepted: 09/23/2020] [Indexed: 02/06/2023]
Abstract
Next generation sequencing (NGS) has allowed the titin gene (TTN) to be identified as a major contributor to neuromuscular disorders, with high clinical heterogeneity. The mechanisms underlying the phenotypic variability and the dominant or recessive pattern of inheritance are unclear. Titin is involved in the formation and stability of the sarcomeres. The effects of the different TTN variants can be harmless or pathogenic (recessive or dominant) but the interpretation is tricky because the current bioinformatics tools can not predict their functional impact effectively. Moreover, TTN variants are very frequent in the general population. The combination of deep phenotyping associated with RNA molecular analyses, western blot (WB) and functional studies is often essential for the interpretation of genetic variants in patients suspected of titinopathy. In line with the current guidelines and suggestions, we implemented for patients with skeletal myopathy and with potentially disease causing TTN variant(s) an integrated genotype-transcripts-protein-phenotype approach, associated with phenotype and variants segregation studies in relatives and confrontation with published data on titinopathies to evaluate pathogenic effects of TTN variants (even truncating ones) on titin transcripts, amount, size and functionality. We illustrate this integrated approach in four patients with recessive congenital myopathy.
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Rich KA, Moscarello T, Siskind C, Brock G, Tan CA, Vatta M, Winder TL, Elsheikh B, Vicini L, Tucker B, Palettas M, Hershberger RE, Kissel JT, Morales A, Roggenbuck J. Novel heterozygous truncating titin variants affecting the A-band are associated with cardiomyopathy and myopathy/muscular dystrophy. Mol Genet Genomic Med 2020; 8:e1460. [PMID: 32815318 PMCID: PMC7549586 DOI: 10.1002/mgg3.1460] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 07/10/2020] [Accepted: 07/31/2020] [Indexed: 11/08/2022] Open
Abstract
BACKGROUND Variants in TTN are frequently identified in the genetic evaluation of skeletal myopathy or cardiomyopathy. However, due to the high frequency of TTN variants in the general population, incomplete penetrance, and limited understanding of the spectrum of disease, interpretation of TTN variants is often difficult for laboratories and clinicians. Currently, cardiomyopathy is associated with heterozygous A-band TTN variants, whereas skeletal myopathy is largely associated with homozygous or compound heterozygous TTN variants. Recent reports show pathogenic variants in TTN may result in a broader phenotypic spectrum than previously recognized. METHODS Here we report the results of a multisite study that characterized the phenotypes of probands with variants in TTN. We investigated TTN genotype-phenotype correlations in probands with skeletal myopathy and/or cardiomyopathy. Probands with TTN truncating variants (TTNtv) or pathogenic missense variants were ascertained from two academic medical centers. Variants were identified via clinical genetic testing and reviewed according to the American College of Medical Genetics criteria. Clinical and family history data were documented via retrospective chart review. Family studies were performed for probands with atypical phenotypes. RESULTS Forty-nine probands were identified with TTNtv or pathogenic missense variants. Probands were classified by clinical presentation: cardiac (n = 30), skeletal muscle (n = 12), or both (cardioskeletal, n = 7). Within the cardioskeletal group, 5/7 probands had heterozygous TTNtv predicted to affect the distal (3') end of the A-band. All cardioskeletal probands had onset of proximal-predominant muscle weakness before diagnosis of cardiovascular disease, five pedigrees support dominant transmission. CONCLUSION Although heterozygous TTNtv in the A-band is known to cause dilated cardiomyopathy, we present evidence that these variants may in some cases cause a novel, dominant skeletal myopathy with a limb-girdle pattern of weakness. These findings emphasize the importance of multidisciplinary care for patients with A-band TTNtv who may be at risk for multisystem disease.
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Affiliation(s)
- Kelly A Rich
- The Ohio State University Wexner Medical Center, The Ohio State University, Columbus, OH, USA
| | - Tia Moscarello
- Stanford Center for Inherited Cardiovascular Disease, Stanford University, Stanford, CA, USA
| | - Carly Siskind
- Stanford Health Care, Stanford University, Stanford, CA, USA
| | - Guy Brock
- The Ohio State University Center for Biostatistics, The Ohio State University, Columbus, OH, USA
| | | | | | | | - Bakri Elsheikh
- The Ohio State University Wexner Medical Center, The Ohio State University, Columbus, OH, USA
| | - Leah Vicini
- The Ohio State University Wexner Medical Center, The Ohio State University, Columbus, OH, USA
| | - Brianna Tucker
- Stanford Center for Inherited Cardiovascular Disease, Stanford University, Stanford, CA, USA
| | - Marilly Palettas
- The Ohio State University Center for Biostatistics, The Ohio State University, Columbus, OH, USA
| | - Ray E Hershberger
- The Ohio State University Wexner Medical Center, The Ohio State University, Columbus, OH, USA
| | - John T Kissel
- The Ohio State University Wexner Medical Center, The Ohio State University, Columbus, OH, USA
| | - Ana Morales
- The Ohio State University Wexner Medical Center, The Ohio State University, Columbus, OH, USA.,Invitae Corporation, San Francisco, CA, USA
| | - Jennifer Roggenbuck
- The Ohio State University Wexner Medical Center, The Ohio State University, Columbus, OH, USA
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62
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Genotype-phenotype correlations in recessive titinopathies. Genet Med 2020; 22:2029-2040. [PMID: 32778822 DOI: 10.1038/s41436-020-0914-2] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 07/15/2020] [Accepted: 07/16/2020] [Indexed: 12/20/2022] Open
Abstract
PURPOSE High throughput sequencing analysis has facilitated the rapid analysis of the entire titin (TTN) coding sequence. This has resulted in the identification of a growing number of recessive titinopathy patients. The aim of this study was to (1) characterize the causative genetic variants and clinical features of the largest cohort of recessive titinopathy patients reported to date and (2) to evaluate genotype-phenotype correlations in this cohort. METHODS We analyzed clinical and genetic data in a cohort of patients with biallelic pathogenic or likely pathogenic TTN variants. The cohort included both previously reported cases (100 patients from 81 unrelated families) and unreported cases (23 patients from 20 unrelated families). RESULTS Overall, 132 causative variants were identified in cohort members. More than half of the cases had hypotonia at birth or muscle weakness and a delayed motor development within the first 12 months of life (congenital myopathy) with causative variants located along the entire gene. The remaining patients had a distal or proximal phenotype and a childhood or later (noncongenital) onset. All noncongenital cases had at least one pathogenic variant in one of the final three TTN exons (362-364). CONCLUSION Our findings suggest a novel association between the location of nonsense variants and the clinical severity of the disease.
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63
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Gao S, Chen SN, Di Nardo C, Lombardi R. Arrhythmogenic Cardiomyopathy and Skeletal Muscle Dystrophies: Shared Histopathological Features and Pathogenic Mechanisms. Front Physiol 2020; 11:834. [PMID: 32848821 PMCID: PMC7406798 DOI: 10.3389/fphys.2020.00834] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Accepted: 06/22/2020] [Indexed: 12/15/2022] Open
Abstract
Arrhythmogenic cardiomyopathy (ACM) is a heritable cardiac disease characterized by fibrotic or fibrofatty myocardial replacement, associated with an increased risk of ventricular arrhythmias and sudden cardiac death. Originally described as a disease of the right ventricle, ACM is currently recognized as a biventricular entity, due to the increasing numbers of reports of predominant left ventricular or biventricular involvement. Research over the last 20 years has significantly advanced our knowledge of the etiology and pathogenesis of ACM. Several etiopathogenetic theories have been proposed; among them, the most attractive one is the dystrophic theory, based on the observation of similar histopathological features between ACM and skeletal muscle dystrophies (SMDs), such as progressive muscular degeneration, inflammation, and tissue replacement by fatty and fibrous tissue. This review will describe the pathophysiological and molecular similarities shared by ACM with SMDs.
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Affiliation(s)
- Shanshan Gao
- Division of Cardiology, Department of Medicine, University of Colorado, Aurora, CO, United States
| | - Suet Nee Chen
- Division of Cardiology, Department of Medicine, University of Colorado, Aurora, CO, United States
| | - Carlo Di Nardo
- Division of Cardiology, Department of Advanced Biomedical Sciences, Federico II University of Naples, Naples, Italy
| | - Raffaella Lombardi
- Division of Cardiology, Department of Medicine, University of Colorado, Aurora, CO, United States.,Division of Cardiology, Department of Advanced Biomedical Sciences, Federico II University of Naples, Naples, Italy
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64
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The ties that bind: functional clusters in limb-girdle muscular dystrophy. Skelet Muscle 2020; 10:22. [PMID: 32727611 PMCID: PMC7389686 DOI: 10.1186/s13395-020-00240-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Accepted: 07/16/2020] [Indexed: 12/13/2022] Open
Abstract
The limb-girdle muscular dystrophies (LGMDs) are a genetically pleiomorphic class of inherited muscle diseases that are known to share phenotypic features. Selected LGMD genetic subtypes have been studied extensively in affected humans and various animal models. In some cases, these investigations have led to human clinical trials of potential disease-modifying therapies, including gene replacement strategies for individual subtypes using adeno-associated virus (AAV) vectors. The cellular localizations of most proteins associated with LGMD have been determined. However, the functions of these proteins are less uniformly characterized, thus limiting our knowledge of potential common disease mechanisms across subtype boundaries. Correspondingly, broad therapeutic strategies that could each target multiple LGMD subtypes remain less developed. We believe that three major "functional clusters" of subcellular activities relevant to LGMD merit further investigation. The best known of these is the glycosylation modifications associated with the dystroglycan complex. The other two, mechanical signaling and mitochondrial dysfunction, have been studied less systematically but are just as promising with respect to the identification of significant mechanistic subgroups of LGMD. A deeper understanding of these disease pathways could yield a new generation of precision therapies that would each be expected to treat a broader range of LGMD patients than a single subtype, thus expanding the scope of the molecular medicines that may be developed for this complex array of muscular dystrophies.
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65
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N2A Titin: Signaling Hub and Mechanical Switch in Skeletal Muscle. Int J Mol Sci 2020; 21:ijms21113974. [PMID: 32492876 PMCID: PMC7312179 DOI: 10.3390/ijms21113974] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Revised: 05/30/2020] [Accepted: 06/01/2020] [Indexed: 02/06/2023] Open
Abstract
Since its belated discovery, our understanding of the giant protein titin has grown exponentially from its humble beginning as a sarcomeric scaffold to recent recognition of its critical mechanical and signaling functions in active muscle. One uniquely useful model to unravel titin’s functions, muscular dystrophy with myositis (mdm), arose spontaneously in mice as a transposon-like LINE repeat insertion that results in a small deletion in the N2A region of titin. This small deletion profoundly affects hypertrophic signaling and muscle mechanics, thereby providing insights into the function of this specific region and the consequences of its dysfunction. The impact of this mutation is profound, affecting diverse aspects of the phenotype including muscle mechanics, developmental hypertrophy, and thermoregulation. In this review, we explore accumulating evidence that points to the N2A region of titin as a dynamic “switch” that is critical for both mechanical and signaling functions in skeletal muscle. Calcium-dependent binding of N2A titin to actin filaments triggers a cascade of changes in titin that affect mechanical properties such as elastic energy storage and return, as well as hypertrophic signaling. The mdm phenotype also points to the existence of as yet unidentified signaling pathways for muscle hypertrophy and thermoregulation, likely involving titin’s PEVK region as well as the N2A signalosome.
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66
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Rivas-Pardo JA, Li Y, Mártonfalvi Z, Tapia-Rojo R, Unger A, Fernández-Trasancos Á, Herrero-Galán E, Velázquez-Carreras D, Fernández JM, Linke WA, Alegre-Cebollada J. A HaloTag-TEV genetic cassette for mechanical phenotyping of proteins from tissues. Nat Commun 2020; 11:2060. [PMID: 32345978 PMCID: PMC7189229 DOI: 10.1038/s41467-020-15465-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2019] [Accepted: 03/09/2020] [Indexed: 11/09/2022] Open
Abstract
Single-molecule methods using recombinant proteins have generated transformative hypotheses on how mechanical forces are generated and sensed in biological tissues. However, testing these mechanical hypotheses on proteins in their natural environment remains inaccesible to conventional tools. To address this limitation, here we demonstrate a mouse model carrying a HaloTag-TEV insertion in the protein titin, the main determinant of myocyte stiffness. Using our system, we specifically sever titin by digestion with TEV protease, and find that the response of muscle fibers to length changes requires mechanical transduction through titin's intact polypeptide chain. In addition, HaloTag-based covalent tethering enables examination of titin dynamics under force using magnetic tweezers. At pulling forces < 10 pN, titin domains are recruited to the unfolded state, and produce 41.5 zJ mechanical work during refolding. Insertion of the HaloTag-TEV cassette in mechanical proteins opens opportunities to explore the molecular basis of cellular force generation, mechanosensing and mechanotransduction.
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Affiliation(s)
- Jaime Andrés Rivas-Pardo
- Department of Biological Sciences, Columbia University, New York, NY, 10027, USA
- Center for Genomics and Bioinformatics, Facultad de Ciencias, Universidad Mayor, Santiago, Chile
| | - Yong Li
- Institute of Physiology II, University of Muenster, Muenster, Germany
| | - Zsolt Mártonfalvi
- Department of Biophysics and Radiation Biology, Semmelweis University, Budapest, Hungary
| | - Rafael Tapia-Rojo
- Department of Biological Sciences, Columbia University, New York, NY, 10027, USA
| | - Andreas Unger
- Institute of Physiology II, University of Muenster, Muenster, Germany
| | | | | | | | - Julio M Fernández
- Department of Biological Sciences, Columbia University, New York, NY, 10027, USA
| | - Wolfgang A Linke
- Institute of Physiology II, University of Muenster, Muenster, Germany.
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67
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Kelly CM, Manukian S, Kim E, Gage MJ. Differences in stability and calcium sensitivity of the Ig domains in titin's N2A region. Protein Sci 2020; 29:1160-1171. [PMID: 32112607 DOI: 10.1002/pro.3848] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 02/17/2020] [Accepted: 02/18/2020] [Indexed: 11/11/2022]
Abstract
Titin is a large filamentous protein that spans half a sarcomere, from Z-disk to M-line. The N2A region within the titin molecule exists between the proximal immunoglobulin (Ig) region and the PEVK region and protein-protein interactions involving this region are required for normal muscle function. The N2A region consists of four Ig domains (I80-I83) with a 105 amino acid linker region between I80 and I81 that has a helical nature. Using chemical stability measurements, we show that predicted differences between the adjacent Ig domains (I81-I83) correlate with experimentally determined differences in chemical stability and refolding kinetics. Our work further shows that I83 has the lowest ΔGunfolding , which is increased in the presence of calcium (pCa 4.3), indicating that Ca2+ plays a role in stabilizing this immunoglobulin domain. The characteristics of N2A's three Ig domains provide insight into the stability of the binding sites for proteins that interact with the N2A region. This work also provides insights into how Ca2+ might influence binding events involving N2A.
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Affiliation(s)
- Colleen M Kelly
- Chemistry Department, University of Massachusetts Lowell, Lowell, Massachusetts, USA.,UMass Movement Center, University of Massachusetts Lowell, Lowell, Massachusetts, USA
| | - Sophia Manukian
- Chemistry Department, University of Massachusetts Lowell, Lowell, Massachusetts, USA
| | - Emily Kim
- Chemistry Department, University of Massachusetts Lowell, Lowell, Massachusetts, USA
| | - Matthew J Gage
- Chemistry Department, University of Massachusetts Lowell, Lowell, Massachusetts, USA.,UMass Movement Center, University of Massachusetts Lowell, Lowell, Massachusetts, USA
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68
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Lange S, Pinotsis N, Agarkova I, Ehler E. The M-band: The underestimated part of the sarcomere. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2020; 1867:118440. [PMID: 30738787 PMCID: PMC7023976 DOI: 10.1016/j.bbamcr.2019.02.003] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 01/16/2019] [Accepted: 02/05/2019] [Indexed: 12/20/2022]
Abstract
The sarcomere is the basic unit of the myofibrils, which mediate skeletal and cardiac Muscle contraction. Two transverse structures, the Z-disc and the M-band, anchor the thin (actin and associated proteins) and thick (myosin and associated proteins) filaments to the elastic filament system composed of titin. A plethora of proteins are known to be integral or associated proteins of the Z-disc and its structural and signalling role in muscle is better understood, while the molecular constituents of the M-band and its function are less well defined. Evidence discussed here suggests that the M-band is important for managing force imbalances during active muscle contraction. Its molecular composition is fine-tuned, especially as far as the structural linkers encoded by members of the myomesin family are concerned and depends on the specific mechanical characteristics of each particular muscle fibre type. Muscle activity signals from the M-band to the nucleus and affects transcription of sarcomeric genes, especially via serum response factor (SRF). Due to its important role as shock absorber in contracting muscle, the M-band is also more and more recognised as a contributor to muscle disease.
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Affiliation(s)
- Stephan Lange
- Biomedical Research Facility 2, School of Medicine, University of California, San Diego, Medical Sciences Research Bldg, 9500 Gilman Drive, La Jolla, CA 92093-0613C, USA; University of Gothenburg, Wallenberg Laboratory, Department of Molecular and Clinical Medicine, Institute of Medicine, Gothenburg, Sweden
| | - Nikos Pinotsis
- Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck College, Malet Street, London WC1E 7HX, UK
| | - Irina Agarkova
- InSphero, Wagistrasse 27, CH-8952 Schlieren, Switzerland
| | - Elisabeth Ehler
- Randall Centre for Cell and Molecular Biophysics, School of Basic and Medical Biosciences, King's College London, New Hunt's House, Guy's Campus, London SE1 1UL, UK; School of Cardiovascular Medicine and Sciences, British Heart Foundation Research Excellence Centre, King's College London, New Hunt's House, Guy's Campus, London SE1 1UL, UK.
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69
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Korpi ER, Lindholm D, Panula P, Tienari PJ, Haltia M. Finnish neuroscience from past to present. Eur J Neurosci 2020; 52:3273-3289. [PMID: 32017266 DOI: 10.1111/ejn.14693] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Revised: 01/24/2020] [Accepted: 01/28/2020] [Indexed: 11/27/2022]
Affiliation(s)
- Esa R Korpi
- Department of Pharmacology, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Dan Lindholm
- Department of Biochemistry and Developmental Biology, Faculty of Medicine, University of Helsinki, Helsinki, Finland.,Minerva Foundation Institute for Medical Research, Helsinki, Finland
| | - Pertti Panula
- Department of Anatomy, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Pentti J Tienari
- Research Programs Unit, Translational Immunology, University of Helsinki, Helsinki, Finland.,Department of Neurology, Neurocenter, Helsinki University Hospital, Helsinki, Finland
| | - Matti Haltia
- Department of Pathology, Faculty of Medicine, University of Helsinki, Helsinki, Finland
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70
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Leal-Gutiérrez JD, Elzo MA, Mateescu RG. Identification of eQTLs and sQTLs associated with meat quality in beef. BMC Genomics 2020; 21:104. [PMID: 32000679 PMCID: PMC6993519 DOI: 10.1186/s12864-020-6520-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Accepted: 01/20/2020] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND Transcription has a substantial genetic control and genetic dissection of gene expression could help us understand the genetic architecture of complex phenotypes such as meat quality in cattle. The objectives of the present research were: 1) to perform eQTL and sQTL mapping analyses for meat quality traits in longissimus dorsi muscle; 2) to uncover genes whose expression is influenced by local or distant genetic variation; 3) to identify expression and splicing hot spots; and 4) to uncover genomic regions affecting the expression of multiple genes. RESULTS Eighty steers were selected for phenotyping, genotyping and RNA-seq evaluation. A panel of traits related to meat quality was recorded in longissimus dorsi muscle. Information on 112,042 SNPs and expression data on 8588 autosomal genes and 87,770 exons from 8467 genes were included in an expression and splicing quantitative trait loci (QTL) mapping (eQTL and sQTL, respectively). A gene, exon and isoform differential expression analysis previously carried out in this population identified 1352 genes, referred to as DEG, as explaining part of the variability associated with meat quality traits. The eQTL and sQTL mapping was performed using a linear regression model in the R package Matrix eQTL. Genotype and year of birth were included as fixed effects, and population structure was accounted for by including as a covariate the first PC from a PCA analysis on genotypic data. The identified QTLs were classified as cis or trans using 1 Mb as the maximum distance between the associated SNP and the gene being analyzed. A total of 8377 eQTLs were identified, including 75.6% trans, 10.4% cis, 12.5% DEG trans and 1.5% DEG cis; while 11,929 sQTLs were uncovered: 66.1% trans, 16.9% DEG trans, 14% cis and 3% DEG cis. Twenty-seven expression master regulators and 13 splicing master regulators were identified and were classified as membrane-associated or cytoskeletal proteins, transcription factors or DNA methylases. These genes could control the expression of other genes through cell signaling or by a direct transcriptional activation/repression mechanism. CONCLUSION In the present analysis, we show that eQTL and sQTL mapping makes possible positional identification of gene and isoform expression regulators.
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Affiliation(s)
| | - Mauricio A Elzo
- Department of Animal Sciences, University of Florida, Gainesville, FL, USA
| | - Raluca G Mateescu
- Department of Animal Sciences, University of Florida, Gainesville, FL, USA
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71
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Heller SA, Shih R, Kalra R, Kang PB. Emery-Dreifuss muscular dystrophy. Muscle Nerve 2019; 61:436-448. [PMID: 31840275 PMCID: PMC7154529 DOI: 10.1002/mus.26782] [Citation(s) in RCA: 73] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Revised: 12/04/2019] [Accepted: 12/07/2019] [Indexed: 12/19/2022]
Abstract
Emery-Dreifuss muscular dystrophy (EDMD) is a rare muscular dystrophy, but is particularly important to diagnose due to frequent life-threatening cardiac complications. EDMD classically presents with muscle weakness, early contractures, cardiac conduction abnormalities and cardiomyopathy, although the presence and severity of these manifestations vary by subtype and individual. Associated genes include EMD, LMNA, SYNE1, SYNE2, FHL1, TMEM43, SUN1, SUN2, and TTN, encoding emerin, lamin A/C, nesprin-1, nesprin-2, FHL1, LUMA, SUN1, SUN2, and titin, respectively. The Online Mendelian Inheritance in Man database recognizes subtypes 1 through 7, which captures most but not all of the associated genes. Genetic diagnosis is essential whenever available, but traditional diagnostic tools can help steer the evaluation toward EDMD and assist with interpretation of equivocal genetic test results. Management is primarily supportive, but it is important to monitor patients closely, especially for potential cardiac complications. There is a high potential for progress in the treatment of EDMD in the coming years.
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Affiliation(s)
- Scott A Heller
- Department of Neurology, University of Florida College of Medicine, Gainesville, Florida
| | - Renata Shih
- Congenital Heart Center, University of Florida College of Medicine, Gainesville, Florida
| | - Raghav Kalra
- Division of Pediatric Neurology, Department of Pediatrics, University of Florida College of Medicine, Gainesville, Florida
| | - Peter B Kang
- Department of Neurology, University of Florida College of Medicine, Gainesville, Florida.,Division of Pediatric Neurology, Department of Pediatrics, University of Florida College of Medicine, Gainesville, Florida.,Genetics Institute and Myology Institute, University of Florida, Gainesville, Florida
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72
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Chatziefthimiou SD, Hornburg P, Sauer F, Mueller S, Ugurlar D, Xu ER, Wilmanns M. Structural diversity in the atomic resolution 3D fingerprint of the titin M-band segment. PLoS One 2019; 14:e0226693. [PMID: 31856237 PMCID: PMC6922384 DOI: 10.1371/journal.pone.0226693] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Accepted: 12/02/2019] [Indexed: 11/18/2022] Open
Abstract
In striated muscles, molecular filaments are largely composed of long protein chains with extensive arrays of identically folded domains, referred to as “beads-on-a-string”. It remains a largely unresolved question how these domains have developed a unique molecular profile such that each carries out a distinct function without false-positive readout. This study focuses on the M-band segment of the sarcomeric protein titin, which comprises ten identically folded immunoglobulin domains. Comparative analysis of high-resolution structures of six of these domains ‒ M1, M3, M4, M5, M7, and M10 ‒ reveals considerable structural diversity within three distinct loops and a non-conserved pattern of exposed cysteines. Our data allow to structurally interpreting distinct pathological readouts that result from titinopathy-associated variants. Our findings support general principles that could be used to identify individual structural/functional profiles of hundreds of identically folded protein domains within the sarcomere and other densely crowded cellular environments.
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Affiliation(s)
| | - Philipp Hornburg
- European Molecular Biology Laboratory, Hamburg Unit, Hamburg, Germany
| | - Florian Sauer
- European Molecular Biology Laboratory, Hamburg Unit, Hamburg, Germany
| | - Simone Mueller
- European Molecular Biology Laboratory, Hamburg Unit, Hamburg, Germany
| | - Deniz Ugurlar
- European Molecular Biology Laboratory, Hamburg Unit, Hamburg, Germany
| | - Emma-Ruoqi Xu
- European Molecular Biology Laboratory, Hamburg Unit, Hamburg, Germany
| | - Matthias Wilmanns
- European Molecular Biology Laboratory, Hamburg Unit, Hamburg, Germany
- University Hamburg Medical Centre Hamburg-Eppendorf, Hamburg, Germany
- * E-mail:
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73
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Khan A, Wang R, Han S, Umair M, Abbas S, Khan MI, Alshabeeb MA, Alfadhel M, Zhang X. Homozygous missense variant in the TTN gene causing autosomal recessive limb-girdle muscular dystrophy type 10. BMC MEDICAL GENETICS 2019; 20:166. [PMID: 31664938 PMCID: PMC6819411 DOI: 10.1186/s12881-019-0895-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Accepted: 09/20/2019] [Indexed: 12/22/2022]
Abstract
Background Limb-girdle muscular dystrophies (LGMDs) are large group of heterogeneous genetic diseases, having a hallmark feature of muscle weakness. Pathogenic mutations in the gene encoding the giant skeletal muscle protein titin (TTN) are associated with several muscle disorders, including cardiomyopathy, recessive congenital myopathies and limb-girdle muscular dystrophy (LGMD) type10. The phenotypic spectrum of titinopathies is expanding, as next generation sequencing (NGS) technology makes screening of this large gene possible. Aim This study aimed to identify the pathogenic variant in a consanguineous Pakistani family with autosomal recessive LGMD type 10. Methods DNA from peripheral blood samples were obtained, whole exome sequencing (WES) was performed and several molecular and bioinformatics analysis were conducted to identify the pathogenic variant. TTN coding and near coding regions were further amplified using PCR and sequenced via Sanger sequencing. Results Whole exome sequencing analysis revealed a novel homozygous missense variant (c.98807G > A; p.Arg32936His) in the TTN gene in the index patients. No heterozygous individuals in the family presented LGMD features. The variant p.Arg32936His leads to a substitution of the arginine amino acid at position 32,936 into histidine possibly causing LGMD type 10. Conclusion We identified a homozygous missense variant in TTN, which likely explains LGMD type 10 in this family in line with similar previously reported data. Our study concludes that WES is a successful molecular diagnostic tool to identify pathogenic variants in large genes such as TTN in highly inbred population.
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Affiliation(s)
- Amjad Khan
- McKusick-Zhang Center for Genetic Medicine, State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing, China.,The Research Center for Medical Genomics, China Medical University, Shenyang, China.,Developmental Medicine Department, King Abdullah International Medical Research Center (KAIMRC), Ministry of National Guard-Health Affairs (MNGHA), King Saud Bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia.,Department of Biochemistry, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan
| | - Rongrong Wang
- McKusick-Zhang Center for Genetic Medicine, State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing, China
| | - Shirui Han
- The Research Center for Medical Genomics, China Medical University, Shenyang, China
| | - Muhammad Umair
- Medical Genomics Research Department, King Abdullah International Medical Research Center (KAIMRC), Ministry of National Guard-Health Affairs (MNGHA), King Saud Bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia
| | - Safdar Abbas
- Department of Biochemistry, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan
| | | | - Mohammad A Alshabeeb
- Developmental Medicine Department, King Abdullah International Medical Research Center (KAIMRC), Ministry of National Guard-Health Affairs (MNGHA), King Saud Bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia
| | - Majid Alfadhel
- Medical Genomics Research Department, King Abdullah International Medical Research Center (KAIMRC), Ministry of National Guard-Health Affairs (MNGHA), King Saud Bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia
| | - Xue Zhang
- McKusick-Zhang Center for Genetic Medicine, State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing, China. .,The Research Center for Medical Genomics, China Medical University, Shenyang, China.
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74
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Savarese M, Maggi L, Vihola A, Jonson PH, Tasca G, Ruggiero L, Bello L, Magri F, Giugliano T, Torella A, Evilä A, Di Fruscio G, Vanakker O, Gibertini S, Vercelli L, Ruggieri A, Antozzi C, Luque H, Janssens S, Pasanisi MB, Fiorillo C, Raimondi M, Ergoli M, Politano L, Bruno C, Rubegni A, Pane M, Santorelli FM, Minetti C, Angelini C, De Bleecker J, Moggio M, Mongini T, Comi GP, Santoro L, Mercuri E, Pegoraro E, Mora M, Hackman P, Udd B, Nigro V. Interpreting Genetic Variants in Titin in Patients With Muscle Disorders. JAMA Neurol 2019; 75:557-565. [PMID: 29435569 DOI: 10.1001/jamaneurol.2017.4899] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Importance Mutations in the titin gene (TTN) cause a wide spectrum of genetic diseases. The interpretation of the numerous rare variants identified in TTN is a difficult challenge given its large size. Objective To identify genetic variants in titin in a cohort of patients with muscle disorders. Design, Setting, and Participants In this case series, 9 patients with titinopathy and 4 other patients with possibly disease-causing variants in TTN were identified. Titin mutations were detected through targeted resequencing performed on DNA from 504 patients with muscular dystrophy, congenital myopathy, or other skeletal muscle disorders. Patients were enrolled from 10 clinical centers in April 2012 to December 2013. All of them had not received a diagnosis after undergoing an extensive investigation, including Sanger sequencing of candidate genes. The data analysis was performed between September 2013 and January 2017. Sequencing data were analyzed using an internal custom bioinformatics pipeline. Main Outcomes and Measures The identification of novel mutations in the TTN gene and novel patients with titinopathy. We performed an evaluation of putative causative variants in the TTN gene, combining genetic, clinical, and imaging data with messenger RNA and/or protein studies. Results Of the 9 novel patients with titinopathy, 5 (55.5%) were men and the mean (SD) age at onset was 25 (15.8) years (range, 0-46 years). Of the 4 other patients (3 men and 1 woman) with possibly disease-causing TTN variants, 2 (50%) had a congenital myopathy and 2 (50%) had a slowly progressive distal myopathy with onset in the second decade. Most of the identified mutations were previously unreported. However, all the variants, even the already described mutations, require careful clinical and molecular evaluation of probands and relatives. Heterozygous truncating variants or unique missense changes are not sufficient to make a diagnosis of titinopathy. Conclusions and Relevance The interpretation of TTN variants often requires further analyses, including a comprehensive evaluation of the clinical phenotype (deep phenotyping) as well as messenger RNA and protein studies. We propose a specific workflow for the clinical interpretation of genetic findings in titin.
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Affiliation(s)
- Marco Savarese
- Folkhälsan Research Center, Medicum, University of Helsinki, Helsinki, Finland.,Dipartimento di Biochimica, Biofisica e Patologia Generale, Università degli Studi della Campania "Luigi Vanvitelli," Napoli, Italy.,Telethon Institute of Genetics and Medicine, Pozzuoli, Italy
| | - Lorenzo Maggi
- Neuromuscular Diseases and Neuroimmunology Unit, Institute for Research and Health Care Foundation Neurological Institute C. Besta, Milan, Italy
| | - Anna Vihola
- Folkhälsan Research Center, Medicum, University of Helsinki, Helsinki, Finland
| | - Per Harald Jonson
- Folkhälsan Research Center, Medicum, University of Helsinki, Helsinki, Finland
| | - Giorgio Tasca
- Istituto di Neurologia, Università Cattolica del Sacro Cuore, Fondazione Policlinico Universitario "A. Gemelli," Rome, Italy
| | - Lucia Ruggiero
- Dipartimento di Neuroscienze e Scienze Riproduttive ed Odontostomatologiche, Università degli Studi di Napoli "Federico II," Napoli, Italy
| | - Luca Bello
- Neuromuscular Center, Dipartimento di Neuroscienze, Università di Padova, Padova, Italy
| | - Francesca Magri
- Centro Dino Ferrari, Dipartimento di Fisiopatologia Medico-Chirurgica e dei Trapianti, Università degli Studi di Milano, Fondazione Institute for Research and Health Care Ca' Granda, Ospedale Maggiore Policlinico, Milan, Italy
| | - Teresa Giugliano
- Dipartimento di Biochimica, Biofisica e Patologia Generale, Università degli Studi della Campania "Luigi Vanvitelli," Napoli, Italy.,Telethon Institute of Genetics and Medicine, Pozzuoli, Italy
| | - Annalaura Torella
- Dipartimento di Biochimica, Biofisica e Patologia Generale, Università degli Studi della Campania "Luigi Vanvitelli," Napoli, Italy.,Telethon Institute of Genetics and Medicine, Pozzuoli, Italy
| | - Anni Evilä
- Folkhälsan Research Center, Medicum, University of Helsinki, Helsinki, Finland
| | - Giuseppina Di Fruscio
- Dipartimento di Biochimica, Biofisica e Patologia Generale, Università degli Studi della Campania "Luigi Vanvitelli," Napoli, Italy.,Telethon Institute of Genetics and Medicine, Pozzuoli, Italy
| | - Olivier Vanakker
- Center for Medical Genetics, Ghent University Hospital, Ghent, Belgium
| | - Sara Gibertini
- Neuromuscular Diseases and Neuroimmunology Unit, Institute for Research and Health Care Foundation Neurological Institute C. Besta, Milan, Italy
| | - Liliana Vercelli
- Neuromuscular Unit, Department of Neurosciences, Rita Levi Montalcini, University of Torino, Torino, Italy
| | - Alessandra Ruggieri
- Neuromuscular Diseases and Neuroimmunology Unit, Institute for Research and Health Care Foundation Neurological Institute C. Besta, Milan, Italy
| | - Carlo Antozzi
- Neuromuscular Diseases and Neuroimmunology Unit, Institute for Research and Health Care Foundation Neurological Institute C. Besta, Milan, Italy
| | - Helena Luque
- Folkhälsan Research Center, Medicum, University of Helsinki, Helsinki, Finland
| | - Sandra Janssens
- Center for Medical Genetics, Ghent University Hospital, Ghent, Belgium
| | - Maria Barbara Pasanisi
- Neuromuscular Diseases and Neuroimmunology Unit, Institute for Research and Health Care Foundation Neurological Institute C. Besta, Milan, Italy
| | - Chiara Fiorillo
- Pediatric Neurology and Neuromuscular Disorders Unit, Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal, and Child Health; University of Genoa, Istituto G. Gaslini, Genova, Italy
| | | | - Manuela Ergoli
- Dipartimento di Medicina Sperimentale, Cardiomiologia e Genetica Medica, Università degli Studi della Campania "Luigi Vanvitelli," Napoli, Italy
| | - Luisa Politano
- Dipartimento di Medicina Sperimentale, Cardiomiologia e Genetica Medica, Università degli Studi della Campania "Luigi Vanvitelli," Napoli, Italy
| | - Claudio Bruno
- Center of Myology and Neurodegenerative Disease, Istituto Giannina Gaslini, Genova, Italy
| | - Anna Rubegni
- Medicina Molecolare, Institute for Research and Health Care Fondazione Stella Maris, Pisa, Italy
| | - Marika Pane
- Department of Pediatric Neurology, Catholic University and Nemo Roma Center for Neuromuscular Disorders, Rome, Italy
| | - Filippo M Santorelli
- Medicina Molecolare, Institute for Research and Health Care Fondazione Stella Maris, Pisa, Italy
| | - Carlo Minetti
- Pediatric Neurology and Neuromuscular Disorders Unit, Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal, and Child Health; University of Genoa, Istituto G. Gaslini, Genova, Italy
| | - Corrado Angelini
- Fondazione Hospital S.Camillo Institute for Research and Health Care, Venezia, Italy
| | - Jan De Bleecker
- Department of Neurology, Ghent University Hospital, Ghent, Belgium
| | - Maurizio Moggio
- Neuromuscular and Rare Disease Unit, Dipartimento di Neuroscienze, Università degli Studi di Milano, Fondazione Institute for Research and Health Care Ca' Granda, Ospedale Maggiore Policlinico, Milano, Italy
| | - Tiziana Mongini
- Neuromuscular Unit, Department of Neurosciences, Rita Levi Montalcini, University of Torino, Torino, Italy
| | - Giacomo Pietro Comi
- Centro Dino Ferrari, Dipartimento di Fisiopatologia Medico-Chirurgica e dei Trapianti, Università degli Studi di Milano, Fondazione Institute for Research and Health Care Ca' Granda, Ospedale Maggiore Policlinico, Milan, Italy
| | - Lucio Santoro
- Dipartimento di Neuroscienze e Scienze Riproduttive ed Odontostomatologiche, Università degli Studi di Napoli "Federico II," Napoli, Italy
| | - Eugenio Mercuri
- Department of Pediatric Neurology, Catholic University and Nemo Roma Center for Neuromuscular Disorders, Rome, Italy
| | - Elena Pegoraro
- Neuromuscular Center, Dipartimento di Neuroscienze, Università di Padova, Padova, Italy
| | - Marina Mora
- Neuromuscular Diseases and Neuroimmunology Unit, Institute for Research and Health Care Foundation Neurological Institute C. Besta, Milan, Italy
| | - Peter Hackman
- Folkhälsan Research Center, Medicum, University of Helsinki, Helsinki, Finland
| | - Bjarne Udd
- Folkhälsan Research Center, Medicum, University of Helsinki, Helsinki, Finland.,Neuromuscular Research Center, University of Tampere and Tampere University Hospital, Tampere, Finland
| | - Vincenzo Nigro
- Dipartimento di Biochimica, Biofisica e Patologia Generale, Università degli Studi della Campania "Luigi Vanvitelli," Napoli, Italy.,Telethon Institute of Genetics and Medicine, Pozzuoli, Italy
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75
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Roggenbuck J, Rich K, Morales A, Tan CA, Eck D, King W, Vatta M, Winder T, Elsheikh B, Hershberger RE, Kissel JT. A novel TTN deletion in a family with skeletal myopathy, facial weakness, and dilated cardiomyopathy. Mol Genet Genomic Med 2019; 7:e924. [PMID: 31489791 PMCID: PMC6825852 DOI: 10.1002/mgg3.924] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Revised: 07/12/2019] [Accepted: 07/26/2019] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND Pathogenic variants in TTN (OMIM 188840), encoding the largest human protein, are known to cause dilated cardiomyopathy and several forms of skeletal myopathy. The clinical interpretation of TTN variants is challenging, however, due to the frequency of missense changes, variable testing and reporting practices in commercial laboratories, and incomplete understanding of the spectrum of TTN-related disease. METHODS We report a heterozygous TTN deletion segregating in a family with an unusual skeletal myopathy phenotype associated with facial weakness, gait abnormality, and dilated cardiomyopathy. RESULTS A novel 16.430 kb heterozygous deletion spanning part of the A- and M-bands of TTN was identified in the proband and his symptomatic son, as well as in an additional son whose symptoms were identified on clinical evaluation. The deletion was found to be de novo in the proband. CONCLUSION Pathogenic variants in TTN may be an unrecognized cause of skeletal myopathy phenotypes, particularly when accompanied by dilated cardiomyopathy.
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Affiliation(s)
| | - Kelly Rich
- The Ohio State University Wexner Medical Center, Columbus, Ohio
| | - Ana Morales
- The Ohio State University Wexner Medical Center, Columbus, Ohio
| | | | - Douglas Eck
- The Ohio State University Wexner Medical Center, Columbus, Ohio
| | - Wendy King
- The Ohio State University Wexner Medical Center, Columbus, Ohio
| | | | | | - Bakri Elsheikh
- The Ohio State University Wexner Medical Center, Columbus, Ohio
| | | | - John T Kissel
- The Ohio State University Wexner Medical Center, Columbus, Ohio
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76
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Oates EC, Jones KJ, Donkervoort S, Charlton A, Brammah S, Smith JE, Ware JS, Yau KS, Swanson LC, Whiffin N, Peduto AJ, Bournazos A, Waddell LB, Farrar MA, Sampaio HA, Teoh HL, Lamont PJ, Mowat D, Fitzsimons RB, Corbett AJ, Ryan MM, O'Grady GL, Sandaradura SA, Ghaoui R, Joshi H, Marshall JL, Nolan MA, Kaur S, Punetha J, Töpf A, Harris E, Bakshi M, Genetti CA, Marttila M, Werlauff U, Streichenberger N, Pestronk A, Mazanti I, Pinner JR, Vuillerot C, Grosmann C, Camacho A, Mohassel P, Leach ME, Foley AR, Bharucha-Goebel D, Collins J, Connolly AM, Gilbreath HR, Iannaccone ST, Castro D, Cummings BB, Webster RI, Lazaro L, Vissing J, Coppens S, Deconinck N, Luk HM, Thomas NH, Foulds NC, Illingworth MA, Ellard S, McLean CA, Phadke R, Ravenscroft G, Witting N, Hackman P, Richard I, Cooper ST, Kamsteeg EJ, Hoffman EP, Bushby K, Straub V, Udd B, Ferreiro A, North KN, Clarke NF, Lek M, Beggs AH, Bönnemann CG, MacArthur DG, Granzier H, Davis MR, Laing NG. Congenital Titinopathy: Comprehensive characterization and pathogenic insights. Ann Neurol 2019; 83:1105-1124. [PMID: 29691892 PMCID: PMC6105519 DOI: 10.1002/ana.25241] [Citation(s) in RCA: 83] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Revised: 04/17/2018] [Accepted: 04/18/2018] [Indexed: 02/06/2023]
Abstract
OBJECTIVE Comprehensive clinical characterization of congenital titinopathy to facilitate diagnosis and management of this important emerging disorder. METHODS Using massively parallel sequencing we identified 30 patients from 27 families with 2 pathogenic nonsense, frameshift and/or splice site TTN mutations in trans. We then undertook a detailed analysis of the clinical, histopathological and imaging features of these patients. RESULTS All patients had prenatal or early onset hypotonia and/or congenital contractures. None had ophthalmoplegia. Scoliosis and respiratory insufficiency typically developed early and progressed rapidly, whereas limb weakness was often slowly progressive, and usually did not prevent independent walking. Cardiac involvement was present in 46% of patients. Relatives of 2 patients had dilated cardiomyopathy. Creatine kinase levels were normal to moderately elevated. Increased fiber size variation, internalized nuclei and cores were common histopathological abnormalities. Cap-like regions, whorled or ring fibers, and mitochondrial accumulations were also observed. Muscle magnetic resonance imaging showed gluteal, hamstring and calf muscle involvement. Western blot analysis showed a near-normal sized titin protein in all samples. The presence of 2 mutations predicted to impact both N2BA and N2B cardiac isoforms appeared to be associated with greatest risk of cardiac involvement. One-third of patients had 1 mutation predicted to impact exons present in fetal skeletal muscle, but not included within the mature skeletal muscle isoform transcript. This strongly suggests developmental isoforms are involved in the pathogenesis of this congenital/early onset disorder. INTERPRETATION This detailed clinical reference dataset will greatly facilitate diagnostic confirmation and management of patients, and has provided important insights into disease pathogenesis. Ann Neurol 2018;83:1105-1124.
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Affiliation(s)
- Emily C Oates
- Dubowitz Neuromuscular Centre, UCL Great Ormond Street Institute of Child Health, London, United Kingdom.,Institute for Neuroscience and Muscle Research, Kid's Research Institute, Children's Hospital at Westmead, Sydney, New South Wales, Australia.,Discipline of Child and Adolescent Health, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia.,School of Biotechnology and Biomolecular Sciences, Faculty of Science, The University of New South Wales, Sydney, New South Wales, Australia
| | - Kristi J Jones
- Institute for Neuroscience and Muscle Research, Kid's Research Institute, Children's Hospital at Westmead, Sydney, New South Wales, Australia.,Discipline of Child and Adolescent Health, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
| | - Sandra Donkervoort
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD
| | - Amanda Charlton
- Discipline of Child and Adolescent Health, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia.,Department of Histopathology, Children's Hospital at Westmead, Sydney, New South Wales, Australia
| | - Susan Brammah
- Electron Microscope Unit, Department of Anatomical Pathology, Concord Repatriation General Hospital, Concord, Sydney, New South Wales, Australia
| | - John E Smith
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ
| | - James S Ware
- National Heart and Lung Institute and MRC London Institute of Medical Science, Imperial College London, London, United Kingdom.,Royal Brompton and Harefield Hospitals NHS Trust, London, United Kingdom
| | - Kyle S Yau
- Institute for Medical Research and Centre for Medical Research, University of Western Australia, Nedlands, Western Australia, Australia
| | - Lindsay C Swanson
- Manton Center for Orphan Disease Research, Division of Genetics and Genomics, Boston Children's Hospital, Harvard Medical School, Boston, MA
| | - Nicola Whiffin
- National Heart and Lung Institute and MRC London Institute of Medical Science, Imperial College London, London, United Kingdom.,Royal Brompton and Harefield Hospitals NHS Trust, London, United Kingdom
| | - Anthony J Peduto
- Department of Radiology, Westmead Hospital, Sydney, New South Wales, Australia.,University of Sydney Western Clinical School, Sydney, New South Wales, Australia
| | - Adam Bournazos
- Institute for Neuroscience and Muscle Research, Kid's Research Institute, Children's Hospital at Westmead, Sydney, New South Wales, Australia.,Discipline of Child and Adolescent Health, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
| | - Leigh B Waddell
- Institute for Neuroscience and Muscle Research, Kid's Research Institute, Children's Hospital at Westmead, Sydney, New South Wales, Australia.,Discipline of Child and Adolescent Health, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
| | - Michelle A Farrar
- Department of Neurology, Sydney Children's Hospital, Sydney, New South Wales, Australia.,School of Women's and Children's Health, University of New South Wales Sydney, Sydney, New South Wales, Australia
| | - Hugo A Sampaio
- Department of Neurology, Sydney Children's Hospital, Sydney, New South Wales, Australia.,School of Women's and Children's Health, University of New South Wales Sydney, Sydney, New South Wales, Australia
| | - Hooi Ling Teoh
- Department of Neurology, Sydney Children's Hospital, Sydney, New South Wales, Australia.,School of Women's and Children's Health, University of New South Wales Sydney, Sydney, New South Wales, Australia
| | - Phillipa J Lamont
- Neurogenetic Unit, Department of Neurology, Royal Perth Hospital, Perth, Western Australia, Australia
| | - David Mowat
- School of Women's and Children's Health, University of New South Wales Sydney, Sydney, New South Wales, Australia.,Department of Medical Genetics, Sydney Children's Hospital, Sydney, New South Wales, Australia
| | - Robin B Fitzsimons
- Sydney Medical School, The University of Sydney, Sydney, New South Wales, Australia
| | - Alastair J Corbett
- Department of Neurology, Concord Repatriation General Hospital, Sydney, New South Wales, Australia
| | - Monique M Ryan
- Department of Neurology, Royal Children's Hospital, Parkville, Victoria, Australia.,Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, Victoria, Australia.,University of Melbourne, Parkville, Victoria, Australia
| | - Gina L O'Grady
- Institute for Neuroscience and Muscle Research, Kid's Research Institute, Children's Hospital at Westmead, Sydney, New South Wales, Australia.,Discipline of Child and Adolescent Health, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia.,Paediatric Neuroservices, Starship Child Health, Auckland, New Zealand
| | - Sarah A Sandaradura
- Institute for Neuroscience and Muscle Research, Kid's Research Institute, Children's Hospital at Westmead, Sydney, New South Wales, Australia.,Discipline of Child and Adolescent Health, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
| | - Roula Ghaoui
- Institute for Neuroscience and Muscle Research, Kid's Research Institute, Children's Hospital at Westmead, Sydney, New South Wales, Australia.,Discipline of Child and Adolescent Health, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
| | - Himanshu Joshi
- Institute for Neuroscience and Muscle Research, Kid's Research Institute, Children's Hospital at Westmead, Sydney, New South Wales, Australia
| | - Jamie L Marshall
- Analytic and Translational Genetics Unit, Massachusetts General Hospital, Boston, MA.,Medical and Population Genetics, Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, MA
| | - Melinda A Nolan
- Paediatric Neuroservices, Starship Child Health, Auckland, New Zealand
| | - Simranpreet Kaur
- Institute for Neuroscience and Muscle Research, Kid's Research Institute, Children's Hospital at Westmead, Sydney, New South Wales, Australia
| | - Jaya Punetha
- Research Center for Genetic Medicine, Children's National Medical Center, Washington, DC.,Department of Integrative Systems Biology, George Washington University School of Medicine and Health Sciences, Washington, DC
| | - Ana Töpf
- John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Elizabeth Harris
- John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Madhura Bakshi
- Department of Clinical Genetics, Liverpool Hospital, Sydney, New South Wales, Australia
| | - Casie A Genetti
- Manton Center for Orphan Disease Research, Division of Genetics and Genomics, Boston Children's Hospital, Harvard Medical School, Boston, MA
| | - Minttu Marttila
- Manton Center for Orphan Disease Research, Division of Genetics and Genomics, Boston Children's Hospital, Harvard Medical School, Boston, MA
| | - Ulla Werlauff
- Danish National Rehabilitation Center for Neuromuscular Diseases, Aarhus, Denmark
| | - Nathalie Streichenberger
- Neuropathology Department, Hospices Civils Lyon, Claude Bernard University, Lyon1, France.,NeuroMyogene Institute, CNRS UMR 5310, INSERM U1217, Lyon, France
| | - Alan Pestronk
- Department of Neurology, Washington University School of Medicine, Saint Louis, MO.,Department of Pathology and Immunology, Washington University School of Medicine, Saint Louis, MO
| | - Ingrid Mazanti
- Cellular Pathology, University Hospital Southampton NHS Foundation Trust, Southampton, United Kingdom
| | - Jason R Pinner
- Department of Medical Genomics, Royal Prince Alfred Hospital, Camperdown, Sydney, New South Wales, Australia
| | - Carole Vuillerot
- Woman-Mother-Child Hospital, Hospices Civils Lyon, Bron, France.,Claude Bernard University Lyon1, France
| | - Carla Grosmann
- University of California, San Diego/Rady Children's Hospital, San Diego, CA
| | - Ana Camacho
- Child Neurology Unit, Department of Neurology, October 12 University Hospital, Faculty of Medicine, Complutense University, Madrid, Spain
| | - Payam Mohassel
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD
| | - Meganne E Leach
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD
| | - A Reghan Foley
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD
| | - Diana Bharucha-Goebel
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD.,Division of Neurology, Children's National Health System, Washington, DC
| | | | - Anne M Connolly
- Neuromuscular Division, Departments of Neurology and Pediatrics, Washington University School of Medicine, Saint Louis, MO
| | - Heather R Gilbreath
- Department of Advanced Practice, Children's Medical Center of Dallas, Dallas, TX
| | - Susan T Iannaccone
- Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX.,Department of Neurology and Neurotherapeutics, University of Texas Southwestern Medical Center, Dallas, TX
| | - Diana Castro
- Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX.,Department of Neurology and Neurotherapeutics, University of Texas Southwestern Medical Center, Dallas, TX
| | - Beryl B Cummings
- Analytic and Translational Genetics Unit, Massachusetts General Hospital, Boston, MA.,Broad Institute of Harvard and Massachusetts Institute of Technology, Cambridge, MA.,Program in Biological and Biomedical Sciences, Harvard Medical School, Boston, MA
| | - Richard I Webster
- T. Y. Nelson Department of Neurology and Neurosurgery, Children's Hospital at Westmead, Sydney, New South Wales, Australia
| | - Leïla Lazaro
- Pediatric Service, Basque Coast Hospital Center, Bayonne, France
| | - John Vissing
- Neuromuscular Clinic and Research Unit, Department of Neurology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Sandra Coppens
- Department of Pediatric Neurology, Neuromuscular Reference Center, Erasmus Hospital, Free University of Brussels, Brussels, Belgium.,Department of Pediatric Neurology, Neuromuscular Reference Center, Queen Fabiola Children's University Hospital, Free University of Brussels, Brussels, Belgium
| | - Nicolas Deconinck
- Department of Pediatric Neurology, Neuromuscular Reference Center, Queen Fabiola Children's University Hospital, Free University of Brussels, Brussels, Belgium
| | - Ho-Ming Luk
- Clinical Genetic Service, Department of Health, Hong Kong, China
| | - Neil H Thomas
- Department of Paediatric Neurology, University Hospital Southampton NHS Foundation Trust, Southampton, United Kingdom
| | - Nicola C Foulds
- Wessex Clinical Genetics Service, University Hospital Southampton NHS Foundation Trust, Southampton, United Kingdom
| | - Marjorie A Illingworth
- Department of Paediatric Neurology, University Hospital Southampton NHS Foundation Trust, Southampton, United Kingdom
| | - Sian Ellard
- University of Exeter Medical School, Exeter, United Kingdom.,Department of Molecular Genetics, Royal Devon and Exeter NHS Foundation Trust, Exeter, United Kingdom
| | - Catriona A McLean
- Department of Anatomical Pathology, Alfred Hospital, Melbourne, Victoria, Australia.,Faculty of Medicine, Nursing, and Health Sciences, Monash University, Melbourne, Victoria, Australia
| | - Rahul Phadke
- Dubowitz Neuromuscular Centre, UCL Great Ormond Street Institute of Child Health, London, United Kingdom.,National Hospital for Neurology and Neurosurgery, UCL Institute of Neurology, London, United Kingdom
| | - Gianina Ravenscroft
- Harry Perkins Institute, University of Western Australia, Nedlands, Western Australia, Australia
| | - Nanna Witting
- Copenhagen Neuromuscular Unit and Department of Neurology, Rigshospitalet, Copenhagen University, Copenhagen, Denmark
| | - Peter Hackman
- Folkhälsan Institute of Genetics, Medicum, University of Helsinki, Helsinki, Finland
| | | | - Sandra T Cooper
- Institute for Neuroscience and Muscle Research, Kid's Research Institute, Children's Hospital at Westmead, Sydney, New South Wales, Australia.,Discipline of Child and Adolescent Health, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
| | - Erik-Jan Kamsteeg
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Eric P Hoffman
- Research Center for Genetic Medicine, Children's National Medical Center, Washington, DC.,Department of Integrative Systems Biology, George Washington University School of Medicine and Health Sciences, Washington, DC
| | - Kate Bushby
- John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Volker Straub
- John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Bjarne Udd
- Folkhälsan Institute of Genetics, Medicum, University of Helsinki, Helsinki, Finland.,Neuromuscular Research Center, Tampere University and University Hospital, Neurology, Tampere, Finland.,Department of Medical Genetics, University of Helsinki, Helsinki, Finland.,Vaasa Central Hospital, Department of Neurology, Vaasa, Finland
| | - Ana Ferreiro
- Pathophysiology of Striated Muscles Laboratory, Unit of Functional and Adaptative Biology, BFA, Paris Diderot University/CNRS, Sorbonne Paris Cité, Paris, France.,Public Hospital Network of Paris, Paris-East Reference Center Neuromuscular Diseases, Pitié-Salpêtrière Hospital Group, Paris, France
| | - Kathryn N North
- Institute for Neuroscience and Muscle Research, Kid's Research Institute, Children's Hospital at Westmead, Sydney, New South Wales, Australia.,Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, Victoria, Australia
| | - Nigel F Clarke
- Institute for Neuroscience and Muscle Research, Kid's Research Institute, Children's Hospital at Westmead, Sydney, New South Wales, Australia.,Discipline of Child and Adolescent Health, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
| | - Monkol Lek
- Analytic and Translational Genetics Unit, Massachusetts General Hospital, Boston, MA.,Broad Institute of Harvard and Massachusetts Institute of Technology, Cambridge, MA
| | - Alan H Beggs
- Manton Center for Orphan Disease Research, Division of Genetics and Genomics, Boston Children's Hospital, Harvard Medical School, Boston, MA
| | - Carsten G Bönnemann
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD
| | - Daniel G MacArthur
- Analytic and Translational Genetics Unit, Massachusetts General Hospital, Boston, MA.,Broad Institute of Harvard and Massachusetts Institute of Technology, Cambridge, MA
| | - Henk Granzier
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ
| | - Mark R Davis
- Department of Diagnostic Genomics, PathWest Laboratory Medicine WA, Nedlands, Western Australia, Australia
| | - Nigel G Laing
- Harry Perkins Institute, University of Western Australia, Nedlands, Western Australia, Australia
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77
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Jang JY, Park Y, Jang DH, Jang JH, Ryu JS. Two novel mutations in TTN of a patient with congenital myopathy: A case report. Mol Genet Genomic Med 2019; 7:e866. [PMID: 31332964 PMCID: PMC6687639 DOI: 10.1002/mgg3.866] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Revised: 07/01/2019] [Accepted: 07/05/2019] [Indexed: 11/23/2022] Open
Abstract
Background Early‐onset myopathies show a wide spectrum of phenotypes and are composed of various types of inherited neuromuscular diseases, making it difficult to diagnose. TTN mutation‐related myopathy is a known cause of early‐onset myopathy. Since a next‐generation sequencing (NGS) has enabled sequencing of the vast amount of DNA, TTN, which is the longest coding sequence of any human gene, mutations can now be revealed. We report a 10‐year‐old female with severe congenital muscular weakness and delayed motor development since birth. Methods Next‐generation sequencing as well as electromyography and muscle biopsy were performed. Results To date, she is incapable of walking alone. Her younger sister had similar but more severe symptoms with respiratory failure. In electromyography, short‐duration, small‐amplitude motor unit action potential, and early recruitment patterns were observed in the involved proximal muscles, suggesting myopathy. Muscle histopathology showed a specific atrophy of increased fiber size variability, frequent nuclear internalization, as well as degeneration and regeneration of fibers with type I fiber predominance, consistent with the findings of a previous report about congenital titinopathy. A NGS study revealed two different possible pathogenic variants in TTN: (a) canonical splicing mutation in the intron 105 (c. 29963‐1G>C) and (b) frameshift and truncating mutation in the exon 339 (c.92812dup/p.Arg30938LysfsTer15). All variants were confirmed by conventional Sanger sequencing. Conclusion We propose that unbiased genomic sequencing can be helpful in screening patients with early‐onset myopathy.
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Affiliation(s)
- Joon Young Jang
- Department of Rehabilitation Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Korea
| | - Yulhyun Park
- Department of Rehabilitation Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Korea
| | - Dae-Hyun Jang
- Department of Rehabilitation Medicine, College of Medicine, The Catholic University of Korea, Seoul, Korea
| | | | - Ju Seok Ryu
- Department of Rehabilitation Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Korea
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78
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Yu M, Zhu Y, Xie Z, Zheng Y, Xiao J, Zhang W, Nishino I, Yuan Y, Wang Z. Novel TTN mutations and muscle imaging characteristics in congenital titinopathy. Ann Clin Transl Neurol 2019; 6:1311-1318. [PMID: 31353864 PMCID: PMC6649615 DOI: 10.1002/acn3.50831] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Revised: 05/31/2019] [Accepted: 06/08/2019] [Indexed: 02/06/2023] Open
Abstract
Objective We present clinical features, muscle imaging findings, and genetic characteristics of five unrelated Chinese patients with congenital titinopathy, emphasizing the diagnostic role of muscle MRI. Methods Five patients who recessive titinopathies were recruited. All patients received muscle biopsies. Mutations were detected by panel massively parallel sequencing and confirmed by Sanger sequencing. Western blotting of muscle proteins was performed. Leg muscle MRIs were performed in four patients. Results Four patients aged 1–4 years old showed delayed motor development from early infancy, while a 17‐year‐old boy showed only a 1‐year history of exercise intolerance. Physical examination showed proximal weakness in three patients. Muscle biopsies demonstrated multiple myopathological changes, including increased internalized nuclei, multicores, central cores, and dystrophic changes. Genetic sequencing revealed compound heterozygous or homozygous novel TTN mutations, including six frameshift mutations, one nonsense mutation, two missense mutations, one splicing mutation, and one small nonframeshift deletion. Protein analyses revealed significant decrease of full‐length titin in all patients. Thigh muscle MRIs in four patients showed prominent fatty infiltration in the upper portion of semitendinosus and the peripheral portion of gluteus medius, while the sartorius and gracilis were relatively preserved. Interpretation These cases provided further evidence that TTN mutations are likely responsible for an increasing proportion of congenital myopathies than currently recognized. The novel mutations reported expand the mutation spectrum of the TTN gene. There is a characteristic pattern of muscle involvement in congenital titinopathy regardless of clinical or pathological phenotype, providing valuable clues for guiding a genetic diagnosis workup.
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Affiliation(s)
- Meng Yu
- Department of Neurology, Peking University First Hospital, Beijing, China
| | - Ying Zhu
- Department of Radiology, Peking University First Hospital, Beijing, China
| | - Zhiying Xie
- Department of Neurology, Peking University First Hospital, Beijing, China
| | - Yiming Zheng
- Department of Neurology, Peking University First Hospital, Beijing, China
| | - Jiangxi Xiao
- Department of Radiology, Peking University First Hospital, Beijing, China
| | - Wei Zhang
- Department of Neurology, Peking University First Hospital, Beijing, China
| | - Ichizo Nishino
- Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry (NCNP), Kodaira, Japan
| | - Yun Yuan
- Department of Neurology, Peking University First Hospital, Beijing, China
| | - Zhaoxia Wang
- Department of Neurology, Peking University First Hospital, Beijing, China
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79
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Caru M, Petrykey K, Drouin S, Beaulieu P, St-Onge P, Lemay V, Bertout L, Laverdiere C, Andelfinger G, Krajinovic M, Sinnett D, Curnier D. Identification of genetic association between cardiorespiratory fitness and the trainability genes in childhood acute lymphoblastic leukemia survivors. BMC Cancer 2019; 19:443. [PMID: 31088516 PMCID: PMC6515640 DOI: 10.1186/s12885-019-5651-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Accepted: 04/29/2019] [Indexed: 01/05/2023] Open
Abstract
BACKGROUND The progress of treatments of childhood acute lymphoblastic leukemia (ALL) has made it possible to reach a survival rate superior to 80%. However, the treatments lead to several long-term adverse effects, including cardiac toxicity. Although studies have reported associations between genetic variants and cardiorespiratory fitness, none has been performed on childhood ALL survivors. METHODS We performed whole-exome sequencing in 239 childhood ALL survivors from the PETALE cohort. Germline variants (both common and rare) in selected set of genes (N = 238) were analyzed for an association with cardiorespiratory fitness. RESULTS Our results showed that the common variant in the TTN gene was significantly associated with a low cardiorespiratory fitness level (p = 0.0005) and that the LEPR, IGFBPI and ENO3 genes were significantly associated with a low cardiorespiratory fitness level in female survivors (p ≤ 0.002). Also, we detected an association between the low cardiorespiratory fitness level in participants that were stratified to the "high risk" prognostic group and functionally predicted rare variants in the SLC22A16 gene (p = 0.001). Positive associations between cardiorespiratory fitness level and trainability genes were mainly observed in females. CONCLUSIONS For the first time, we observed that low cardiorespiratory fitness in childhood ALL survivors can be associated with variants in genes related to subjects' trainability. These findings could allow better childhood ALL patient follow-up tailored to their genetic profile and cardiorespiratory fitness, which could help reduce at least some of the burden of long-term adverse effects of treatments.
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Affiliation(s)
- Maxime Caru
- Laboratoire de Physiopathologie de l'EXercice (LPEX), École de Kinésiologie et des Sciences de l'Activité physique, Faculté de Médecine, Université de Montréal, CEPSUM, 2100, boulevard Édouard Montpetit, Montréal, QC, H3C 3J7, Canada. .,Department of psychology, Laboratoire EA 4430 - Clinique Psychanalyse Developpement (CliPsyD), University of Paris Nanterre, Nanterre, Ile-de-France, France. .,Research Center, Sainte-Justine University Health Center, Montreal, Quebec, Canada.
| | - Kateryna Petrykey
- Research Center, Sainte-Justine University Health Center, Montreal, Quebec, Canada.,Department of pharmacology and physiology, University of Montreal, Montreal, Quebec, Canada
| | - Simon Drouin
- Research Center, Sainte-Justine University Health Center, Montreal, Quebec, Canada
| | - Patrick Beaulieu
- Research Center, Sainte-Justine University Health Center, Montreal, Quebec, Canada
| | - Pascal St-Onge
- Research Center, Sainte-Justine University Health Center, Montreal, Quebec, Canada
| | - Valérie Lemay
- Laboratoire de Physiopathologie de l'EXercice (LPEX), École de Kinésiologie et des Sciences de l'Activité physique, Faculté de Médecine, Université de Montréal, CEPSUM, 2100, boulevard Édouard Montpetit, Montréal, QC, H3C 3J7, Canada.,Research Center, Sainte-Justine University Health Center, Montreal, Quebec, Canada
| | - Laurence Bertout
- Research Center, Sainte-Justine University Health Center, Montreal, Quebec, Canada
| | - Caroline Laverdiere
- Research Center, Sainte-Justine University Health Center, Montreal, Quebec, Canada.,Department of Pediatrics, University of Montreal, Montreal, Quebec, Canada
| | - Gregor Andelfinger
- Research Center, Sainte-Justine University Health Center, Montreal, Quebec, Canada.,Department of Pediatrics, University of Montreal, Montreal, Quebec, Canada
| | - Maja Krajinovic
- Research Center, Sainte-Justine University Health Center, Montreal, Quebec, Canada.,Department of pharmacology and physiology, University of Montreal, Montreal, Quebec, Canada.,Department of Pediatrics, University of Montreal, Montreal, Quebec, Canada
| | - Daniel Sinnett
- Research Center, Sainte-Justine University Health Center, Montreal, Quebec, Canada.,Department of Pediatrics, University of Montreal, Montreal, Quebec, Canada
| | - Daniel Curnier
- Laboratoire de Physiopathologie de l'EXercice (LPEX), École de Kinésiologie et des Sciences de l'Activité physique, Faculté de Médecine, Université de Montréal, CEPSUM, 2100, boulevard Édouard Montpetit, Montréal, QC, H3C 3J7, Canada.,Research Center, Sainte-Justine University Health Center, Montreal, Quebec, Canada
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80
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Algahtani H, Shirah B, Algahtani R, Al-Qahtani MH, Abdulkareem AA, Naseer MI. A novel mutation in TTN gene in a Saudi patient with bilateral facial weakness and scapular winging. Intractable Rare Dis Res 2019; 8:142-145. [PMID: 31218166 PMCID: PMC6557229 DOI: 10.5582/irdr.2019.01052] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
Titin (TTN) is a large gene with 363 exons that encodes a large abundant protein (longest known polypeptide in nature) that is expressed in cardiac and skeletal muscles. TTN has an important role in the sarcomere organization, assembly of muscles, transmission of the force at the Z-line, passive myocyte stiffness, and resting tension maintenance in the I-band region. Mutation in extreme C terminus of TTN, situated at the end of M-band of the TTN in chromosome 2q31, results in tibial muscular dystrophy (TMD), also called Udd Distal Myopathy, which is an autosomal dominant distal myopathy. In this article, we report a novel mutation in TTN gene in a Saudi patient with bilateral facial weakness and scapular winging. This report adds to the literature a heterozygous missense variant c.85652C>G, p.(Pro28551Arg) in TTN gene, which may be related to genes that cause the disease, but more case validation is needed. The novel mutation described in the present study widened the genetic spectrum of TTN-associated diseases, which may benefit studies addressing this disease in the future.
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Affiliation(s)
- Hussein Algahtani
- King Abdulaziz Medical City / King Saud bin Abdulaziz University for Health Sciences, Jeddah, Saudi Arabia
- Address correspondence to:Dr. Hussein Algahtani, King Abdulaziz Medical City/King Saud bin Abdulaziz University for Health Sciences, P.O. Box: 12723, Jeddah 21483, Saudi Arabia. Contact No.: 00966556633130. E-mail:
| | - Bader Shirah
- King Abdullah International Medical Research Center/King Saud bin Abdulaziz University for Health Sciences, Jeddah, Saudi Arabia
| | - Raghad Algahtani
- King Saud bin Abdulaziz University for Health Sciences, Jeddah, Saudi Arabia
| | - Mohammad H. Al-Qahtani
- Center of Excellence in Genomic Medicine Research, King Abdulaziz University, Jeddah, Saudi Arabia
| | | | - Muhammad Imran Naseer
- Center of Excellence in Genomic Medicine Research, King Abdulaziz University, Jeddah, Saudi Arabia
- Department of Medical Laboratory Technology, Faculty of Applied Medical Sciences, King Abdulaziz University, Jeddah, Saudi Arabia
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81
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Khan TN, Khan K, Sadeghpour A, Reynolds H, Perilla Y, McDonald MT, Gallentine WB, Baig SM, Davis EE, Katsanis N. Mutations in NCAPG2 Cause a Severe Neurodevelopmental Syndrome that Expands the Phenotypic Spectrum of Condensinopathies. Am J Hum Genet 2019; 104:94-111. [PMID: 30609410 PMCID: PMC6323578 DOI: 10.1016/j.ajhg.2018.11.017] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Accepted: 11/26/2018] [Indexed: 01/29/2023] Open
Abstract
The use of whole-exome and whole-genome sequencing has been a catalyst for a genotype-first approach to diagnostics. Under this paradigm, we have implemented systematic sequencing of neonates and young children with a suspected genetic disorder. Here, we report on two families with recessive mutations in NCAPG2 and overlapping clinical phenotypes that include severe neurodevelopmental defects, failure to thrive, ocular abnormalities, and defects in urogenital and limb morphogenesis. NCAPG2 encodes a member of the condensin II complex, necessary for the condensation of chromosomes prior to cell division. Consistent with a causal role for NCAPG2, we found abnormal chromosome condensation, augmented anaphase chromatin-bridge formation, and micronuclei in daughter cells of proband skin fibroblasts. To test the functional relevance of the discovered variants, we generated an ncapg2 zebrafish model. Morphants displayed clinically relevant phenotypes, such as renal anomalies, microcephaly, and concomitant increases in apoptosis and altered mitotic progression. These could be rescued by wild-type but not mutant human NCAPG2 mRNA and were recapitulated in CRISPR-Cas9 F0 mutants. Finally, we noted that the individual with a complex urogenital defect also harbored a heterozygous NPHP1 deletion, a common contributor to nephronophthisis. To test whether sensitization at the NPHP1 locus might contribute to a more severe renal phenotype, we co-suppressed nphp1 and ncapg2, which resulted in significantly more dysplastic renal tubules in zebrafish larvae. Together, our data suggest that impaired function of NCAPG2 results in a severe condensinopathy, and they highlight the potential utility of examining candidate pathogenic lesions beyond the primary disease locus.
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Affiliation(s)
- Tahir N Khan
- Center for Human Disease Modeling, Duke University, Durham, NC 27701, USA
| | - Kamal Khan
- Center for Human Disease Modeling, Duke University, Durham, NC 27701, USA; Human Molecular Genetics Laboratory, Health Biotechnology Division, National Institute for Biotechnology and Genetic Engineering, Faisalabad, Pakistan
| | - Azita Sadeghpour
- Center for Human Disease Modeling, Duke University, Durham, NC 27701, USA
| | - Hannah Reynolds
- Center for Human Disease Modeling, Duke University, Durham, NC 27701, USA; Furman University, Greenville, SC 29613, USA
| | - Yezmin Perilla
- Center for Human Disease Modeling, Duke University, Durham, NC 27701, USA
| | - Marie T McDonald
- Department of Pediatrics, Division of Medical Genetics, Duke University Medical Center, Durham, NC 27710, USA
| | - William B Gallentine
- Department of Pediatrics, Division of Pediatric Neurology, Duke University Medical Center, Durham, NC 27710, USA
| | - Shahid M Baig
- Human Molecular Genetics Laboratory, Health Biotechnology Division, National Institute for Biotechnology and Genetic Engineering, Faisalabad, Pakistan
| | - Erica E Davis
- Center for Human Disease Modeling, Duke University, Durham, NC 27701, USA.
| | - Nicholas Katsanis
- Center for Human Disease Modeling, Duke University, Durham, NC 27701, USA.
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82
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The power of the force: mechano-physiology of the giant titin. Emerg Top Life Sci 2018; 2:681-686. [PMID: 33530662 DOI: 10.1042/etls20180046] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 11/23/2018] [Accepted: 11/26/2018] [Indexed: 01/18/2023]
Abstract
Titin - the largest protein in the human body - spans half of the muscle sarcomere from the Z-disk to the M-band through a single polypeptide chain. More than 30 000 amino acid residues coded from a single gene (TTN, in humans Q8WZ42) form a long filamentous protein organized in individual globular domains concatenated in tandem. Owing to its location and close interaction with the other muscle filaments, titin is considered the third filament of muscle, after the thick-myosin and the thin-actin filaments.
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83
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Choi SH, Lu-Chen W, Roselli C, Lin H, Haggerty CM, Shoemaker MB, Barnard J, Arking DE, Chasman DI, Albert CM, Chaffin M, Tucker NR, Smith JD, Gupta N, Gabriel S, Margolin L, Shea MA, Shaffer CM, Yoneda ZT, Boerwinkle E, Smith NL, Silverman EK, Redline S, Vasan RS, Burchard EG, Gogarten SM, Laurie C, Blackwell TW, Abecasis G, Carey DJ, Fornwalt BK, Smelser DT, Baras A, Dewey FE, Jaquish CE, Papanicolaou GJ, Sotoodehnia N, Van Wagoner DR, Psaty BM, Kathiresan S, Darbar D, Alonso A, Heckbert SR, Chung MK, Roden DM, Benjamin EJ, Murray MF, Lunetta KL, Lubitz SA, Ellinor PT. Association Between Titin Loss-of-Function Variants and Early-Onset Atrial Fibrillation. JAMA 2018; 320:2354-2364. [PMID: 30535219 PMCID: PMC6436530 DOI: 10.1001/jama.2018.18179] [Citation(s) in RCA: 143] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Importance Atrial fibrillation (AF) is the most common arrhythmia affecting 1% of the population. Young individuals with AF have a strong genetic association with the disease, but the mechanisms remain incompletely understood. Objective To perform large-scale whole-genome sequencing to identify genetic variants related to AF. Design, Setting, and Participants The National Heart, Lung, and Blood Institute's Trans-Omics for Precision Medicine Program includes longitudinal and cohort studies that underwent high-depth whole-genome sequencing between 2014 and 2017 in 18 526 individuals from the United States, Mexico, Puerto Rico, Costa Rica, Barbados, and Samoa. This case-control study included 2781 patients with early-onset AF from 9 studies and identified 4959 controls of European ancestry from the remaining participants. Results were replicated in the UK Biobank (346 546 participants) and the MyCode Study (42 782 participants). Exposures Loss-of-function (LOF) variants in genes at AF loci and common genetic variation across the whole genome. Main Outcomes and Measures Early-onset AF (defined as AF onset in persons <66 years of age). Due to multiple testing, the significance threshold for the rare variant analysis was P = 4.55 × 10-3. Results Among 2781 participants with early-onset AF (the case group), 72.1% were men, and the mean (SD) age of AF onset was 48.7 (10.2) years. Participants underwent whole-genome sequencing at a mean depth of 37.8 fold and mean genome coverage of 99.1%. At least 1 LOF variant in TTN, the gene encoding the sarcomeric protein titin, was present in 2.1% of case participants compared with 1.1% in control participants (odds ratio [OR], 1.76 [95% CI, 1.04-2.97]). The proportion of individuals with early-onset AF who carried a LOF variant in TTN increased with an earlier age of AF onset (P value for trend, 4.92 × 10-4), and 6.5% of individuals with AF onset prior to age 30 carried a TTN LOF variant (OR, 5.94 [95% CI, 2.64-13.35]; P = 1.65 × 10-5). The association between TTN LOF variants and AF was replicated in an independent study of 1582 patients with early-onset AF (cases) and 41 200 control participants (OR, 2.16 [95% CI, 1.19-3.92]; P = .01). Conclusions and Relevance In a case-control study, there was a statistically significant association between an LOF variant in the TTN gene and early-onset AF, with the variant present in a small percentage of participants with early-onset AF (the case group). Further research is necessary to understand whether this is a causal relationship.
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Affiliation(s)
- Seung Hoan Choi
- Program in Medical and Population Genetics, The Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Weng Lu-Chen
- Program in Medical and Population Genetics, The Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Cardiovascular Research Center, Massachusetts General Hospital, Boston, MA, USA
| | - Carolina Roselli
- Program in Medical and Population Genetics, The Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Honghuang Lin
- NHLBI and Boston University’s Framingham Heart Study, Framingham, MA, USA
- Section of Computational Biomedicine, Department of Medicine, Boston University School of Medicine, Boston, MA, USA
| | | | - M. Benjamin Shoemaker
- Departments of Medicine, Pharmacology, and Biomedical Informatics, Vanderbilt University Medical Center, Nashville, TN, USA
| | - John Barnard
- Departments of Quantitative Health Sciences, Cleveland Clinic, Cleveland, OH, USA
| | - Dan E. Arking
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Daniel I. Chasman
- Program in Medical and Population Genetics, The Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Divisions of Preventive Medicine and Genetics, Brigham and Women’s Hospital & Harvard Medical School, Boston, MA, USA
| | - Christine M. Albert
- Divisions of Preventive and Cardiovascular Medicine, Brigham and Women’s Hospital & Harvard Medical School, Boston, MA, USA
| | - Mark Chaffin
- Program in Medical and Population Genetics, The Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Nathan R. Tucker
- Program in Medical and Population Genetics, The Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Cardiovascular Research Center, Massachusetts General Hospital, Boston, MA, USA
| | - Jonathan D. Smith
- Departments of Cellular and Molecular Medicine, Cleveland Clinic, Cleveland, OH, USA
| | - Namrata Gupta
- Program in Medical and Population Genetics, The Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Stacey Gabriel
- Program in Medical and Population Genetics, The Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Lauren Margolin
- Program in Medical and Population Genetics, The Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Marisa A. Shea
- Cardiovascular Research Center, Massachusetts General Hospital, Boston, MA, USA
| | - Christian M. Shaffer
- Departments of Medicine, Pharmacology, and Biomedical Informatics, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Zachary T. Yoneda
- Departments of Medicine, Pharmacology, and Biomedical Informatics, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Eric Boerwinkle
- Human Genetics Center, Department of Epidemiology, Human Genetics and Environmental Sciences, School of Public Health, The University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Nicholas L. Smith
- Department of Epidemiology and Cardiovascular Health Research Unit, University of Washington, Seattle, WA, USA
| | - Edwin K. Silverman
- Channing Division of Network Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, USA
| | - Susan Redline
- Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women’s Hospital, Boston, MA, USA
| | | | - Esteban G. Burchard
- Department of Bioengineering, School of Pharmacy, University of California, San Francisco, CA, USA
| | | | - Cecelia Laurie
- Department of Biostatistics, University of Washington, Seattle, WA, USA
| | - Thomas W. Blackwell
- Center for Statistical Genetics, Department of Biostatistics, University of Michigan School of Public Health, Ann Arbor, MI, USA
| | - Gonçalo Abecasis
- Center for Statistical Genetics, Department of Biostatistics, University of Michigan School of Public Health, Ann Arbor, MI, USA
| | - David J. Carey
- Department of Molecular and Functional Genomics, Geisinger, Danville, PA, USA
| | | | - Diane T. Smelser
- Department of Molecular and Functional Genomics, Geisinger, Danville, PA, USA
| | - Aris Baras
- Regeneron Genetics Center, Tarrytown, NY, USA
| | | | - Cashell E. Jaquish
- Division of Cardiovascular Sciences, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - George J. Papanicolaou
- Division of Cardiovascular Sciences, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Nona Sotoodehnia
- Cardiovascular Health Research Unit, Department of Medicine, University of Washington, Seattle, WA, USA
| | | | - Bruce M. Psaty
- Department of Epidemiology and Cardiovascular Health Research Unit, University of Washington, Seattle, WA, USA
- Cardiovascular Health Research Unit, Department of Medicine, University of Washington, Seattle, WA, USA
- Kaiser Permanente Washington Health Research Institute, Seattle, WA, USA
- Department of Health Services, University of Washington, Seattle, WA, USA
| | - Sekar Kathiresan
- Program in Medical and Population Genetics, The Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Dawood Darbar
- Division of Cardiology, Department of Medicine, University of Illinois, Chicago, IL, USA
| | - Alvaro Alonso
- Department of Epidemiology, Rollins School of Public Health, Emory University, Atlanta, GA, USA
| | - Susan R. Heckbert
- Department of Epidemiology and Cardiovascular Health Research Unit, University of Washington, Seattle, WA, USA
- Kaiser Permanente Washington Health Research Institute, Seattle, WA, USA
| | - Mina K. Chung
- Departments of Cardiovascular Medicine, Cleveland Clinic, Cleveland, OH, USA
| | - Dan M. Roden
- Departments of Medicine, Pharmacology, and Biomedical Informatics, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Emelia J. Benjamin
- NHLBI and Boston University’s Framingham Heart Study, Framingham, MA, USA
- Department of Medicine, Boston University School of Medicine, Boston, MA, USA
- Department of Epidemiology, Boston University School of Public Health, Boston, MA, USA
| | | | - Kathryn L. Lunetta
- NHLBI and Boston University’s Framingham Heart Study, Framingham, MA, USA
- Department of Biostatistics, Boston University School of Public Health, Boston, MA, USA
| | - Steven A. Lubitz
- Program in Medical and Population Genetics, The Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Cardiovascular Research Center, Massachusetts General Hospital, Boston, MA, USA
- Cardiac Arrhythmia Service, Massachusetts General Hospital, Boston, MA, USA
| | - Patrick T. Ellinor
- Program in Medical and Population Genetics, The Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Cardiovascular Research Center, Massachusetts General Hospital, Boston, MA, USA
- Cardiac Arrhythmia Service, Massachusetts General Hospital, Boston, MA, USA
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84
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Milone M, Liewluck T. The unfolding spectrum of inherited distal myopathies. Muscle Nerve 2018; 59:283-294. [PMID: 30171629 DOI: 10.1002/mus.26332] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Revised: 08/26/2018] [Accepted: 08/28/2018] [Indexed: 12/30/2022]
Abstract
Distal myopathies are a group of rare muscle diseases characterized by distal weakness at onset. Although acquired myopathies can occasionally present with distal weakness, the majority of distal myopathies have a genetic etiology. Their age of onset varies from early-childhood to late-adulthood while the predominant muscle weakness can affect calf, ankle dorsiflexor, or distal upper limb muscles. A spectrum of muscle pathological changes, varying from nonspecific myopathic changes to rimmed vacuoles to myofibrillar pathology to nuclei centralization, have been noted. Likewise, the underlying molecular defect is heterogeneous. In addition, there is emerging evidence that distal myopathies can result from defective proteins encoded by genes causative of neurogenic disorders, be manifestation of multisystem proteinopathies or the result of the altered interplay between different genes. In this review, we provide an overview on the clinical, electrophysiological, pathological, and molecular aspects of distal myopathies, focusing on the most recent developments in the field. Muscle Nerve 59:283-294, 2019.
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Affiliation(s)
| | - Teerin Liewluck
- Department of Neurology, Mayo Clinic, Rochester, Minnesota, USA
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85
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Chardon JW, Jasmin BJ, Kothary R, Parks RJ. Report on the 4th Ottawa International Conference on Neuromuscular Disease and Biology - September 5-7, 2017, Ottawa, Canada. J Neuromuscul Dis 2018; 5:539-552. [PMID: 30373960 DOI: 10.3233/jnd-180353] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Jodi Warman Chardon
- Department of Medicine, The Ottawa Hospital and University of Ottawa, ON, Canada.,Department of Pediatrics (Genetics), Children's Hospital of Eastern Ontario, ON, Canada.,Neuroscience Program, Ottawa Hospital Research Institute, ON, Canada.,Centre for Neuromuscular Disease, University of Ottawa, ON, Canada.,Department of Cellular and Molecular Medicine, University of Ottawa, ON, Canada
| | - Bernard J Jasmin
- Centre for Neuromuscular Disease, University of Ottawa, ON, Canada.,Department of Cellular and Molecular Medicine, University of Ottawa, ON, Canada
| | - Rashmi Kothary
- Department of Medicine, The Ottawa Hospital and University of Ottawa, ON, Canada.,Centre for Neuromuscular Disease, University of Ottawa, ON, Canada.,Department of Cellular and Molecular Medicine, University of Ottawa, ON, Canada.,Regenerative Medicine Program, Ottawa Hospital Research Institute, ON, Canada
| | - Robin J Parks
- Department of Medicine, The Ottawa Hospital and University of Ottawa, ON, Canada.,Centre for Neuromuscular Disease, University of Ottawa, ON, Canada.,Regenerative Medicine Program, Ottawa Hospital Research Institute, ON, Canada.,Department of Biochemistry, Microbiology and Immunology, University of Ottawa, ON, Canada
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86
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Yoshihisa A, Kiko T, Sato T, Oikawa M, Kobayashi A, Takeishi Y. Urinary N-terminal fragment of titin is a marker to diagnose muscular dystrophy in patients with cardiomyopathy. Clin Chim Acta 2018; 484:226-230. [DOI: 10.1016/j.cca.2018.06.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2018] [Revised: 05/30/2018] [Accepted: 06/01/2018] [Indexed: 12/22/2022]
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87
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Translating emerging molecular genetic insights into clinical practice in inherited cardiomyopathies. J Mol Med (Berl) 2018; 96:993-1024. [PMID: 30128729 DOI: 10.1007/s00109-018-1685-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Revised: 07/22/2018] [Accepted: 08/08/2018] [Indexed: 12/19/2022]
Abstract
Cardiomyopathies are primarily genetic disorders of the myocardium associated with higher risk of life-threatening cardiac arrhythmias, heart failure, and sudden cardiac death. The evolving knowledge in genomic medicine during the last decade has reshaped our understanding of cardiomyopathies as diseases of multifactorial nature and complex pathophysiology. Genetic testing in cardiomyopathies has subsequently grown from primarily a research tool into an essential clinical evaluation piece with important clinical implications for patients and their families. The purpose of this review is to provide with a contemporary insight into the implications of genetic testing in diagnosis, therapy, and prognosis of patients with inherited cardiomyopathies. Here, we summarize the contemporary knowledge on genotype-phenotype correlations in inherited cardiomyopathies and highlight the recent significant achievements in the field of translational cardiovascular genetics.
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88
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Prioritization of Variants Detected by Next Generation Sequencing According to the Mutation Tolerance and Mutational Architecture of the Corresponding Genes. Int J Mol Sci 2018; 19:ijms19061584. [PMID: 29861492 PMCID: PMC6032105 DOI: 10.3390/ijms19061584] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Revised: 05/09/2018] [Accepted: 05/23/2018] [Indexed: 12/27/2022] Open
Abstract
The biggest challenge geneticists face when applying next-generation sequencing technology to the diagnosis of rare diseases is determining which rare variants, from the dozens or hundreds detected, are potentially implicated in the patient’s phenotype. Thus, variant prioritization is an essential step in the process of rare disease diagnosis. In addition to conducting the usual in-silico analyses to predict variant pathogenicity (based on nucleotide/amino-acid conservation and the differences between the physicochemical features of the amino-acid change), three important concepts should be borne in mind. The first is the “mutation tolerance” of the genes in which variants are located. This describes the susceptibility of a given gene to any functional mutation and depends on the strength of purifying selection acting against it. The second is the “mutational architecture” of each gene. This describes the type and location of mutations previously identified in the gene, and their association with different phenotypes or degrees of severity. The third is the mode of inheritance (inherited vs. de novo) of the variants detected. Here, we discuss the importance of each of these concepts for variant prioritization in the diagnosis of rare diseases. Using real data, we show how genes, rather than variants, can be prioritized by calculating a gene-specific mutation tolerance score. We also illustrate the influence of mutational architecture on variant prioritization using five paradigmatic examples. Finally, we discuss the importance of familial variant analysis as final step in variant prioritization.
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89
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Savarese M, Sarparanta J, Vihola A, Udd B, Hackman P. Increasing Role of Titin Mutations in Neuromuscular Disorders. J Neuromuscul Dis 2018; 3:293-308. [PMID: 27854229 PMCID: PMC5123623 DOI: 10.3233/jnd-160158] [Citation(s) in RCA: 92] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The TTN gene with 363 coding exons encodes titin, a giant muscle protein spanning from the Z-disk to the M-band within the sarcomere. Mutations in the TTN gene have been associated with different genetic disorders, including hypertrophic and dilated cardiomyopathy and several skeletal muscle diseases. Before the introduction of next generation sequencing (NGS) methods, the molecular analysis of TTN has been laborious, expensive and not widely used, resulting in a limited number of mutations identified. Recent studies however, based on the use of NGS strategies, give evidence of an increasing number of rare and unique TTN variants. The interpretation of these rare variants of uncertain significance (VOUS) represents a challenge for clinicians and researchers. The main aim of this review is to describe the wide spectrum of muscle diseases caused by TTN mutations so far determined, summarizing the molecular findings as well as the clinical data, and to highlight the importance of joint efforts to respond to the challenges arising from the use of NGS. An international collaboration through a clinical and research consortium and the development of a single accessible database listing variants in the TTN gene, identified by high throughput approaches, may be the key to a better assessment of titinopathies and to systematic genotype– phenotype correlation studies.
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Affiliation(s)
- Marco Savarese
- Folkhälsan Institute of Genetics and Department of Medical Genetics, Haartman Institute, University of Helsinki, Helsinki, Finland
| | - Jaakko Sarparanta
- Folkhälsan Institute of Genetics and Department of Medical Genetics, Haartman Institute, University of Helsinki, Helsinki, Finland.,Albert Einstein College of Medicine, Departments of Medicine- Endocrinology and Molecular Pharmacology, Bronx, NY, USA
| | - Anna Vihola
- Folkhälsan Institute of Genetics and Department of Medical Genetics, Haartman Institute, University of Helsinki, Helsinki, Finland
| | - Bjarne Udd
- Folkhälsan Institute of Genetics and Department of Medical Genetics, Haartman Institute, University of Helsinki, Helsinki, Finland.,Neuromuscular Research Center, University of Tampere and Tampere University Hospital, Tampere, Finland.,Department of Neurology, Vaasa Central Hospital, Vaasa, Finland
| | - Peter Hackman
- Folkhälsan Institute of Genetics and Department of Medical Genetics, Haartman Institute, University of Helsinki, Helsinki, Finland
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90
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Punetha J, Kesari A, Uapinyoying P, Giri M, Clarke NF, Waddell LB, North KN, Ghaoui R, O'Grady GL, Oates EC, Sandaradura SA, Bönnemann CG, Donkervoort S, Plotz PH, Smith EC, Tesi-Rocha C, Bertorini TE, Tarnopolsky MA, Reitter B, Hausmanowa-Petrusewicz I, Hoffman EP. Targeted Re-Sequencing Emulsion PCR Panel for Myopathies: Results in 94 Cases. J Neuromuscul Dis 2018; 3:209-225. [PMID: 27854218 DOI: 10.3233/jnd-160151] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
BACKGROUND Molecular diagnostics in the genetic myopathies often requires testing of the largest and most complex transcript units in the human genome (DMD, TTN, NEB). Iteratively targeting single genes for sequencing has traditionally entailed high costs and long turnaround times. Exome sequencing has begun to supplant single targeted genes, but there are concerns regarding coverage and needed depth of the very large and complex genes that frequently cause myopathies. OBJECTIVE To evaluate efficiency of next-generation sequencing technologies to provide molecular diagnostics for patients with previously undiagnosed myopathies. METHODS We tested a targeted re-sequencing approach, using a 45 gene emulsion PCR myopathy panel, with subsequent sequencing on the Illumina platform in 94 undiagnosed patients. We compared the targeted re-sequencing approach to exome sequencing for 10 of these patients studied. RESULTS We detected likely pathogenic mutations in 33 out of 94 patients with a molecular diagnostic rate of approximately 35%. The remaining patients showed variants of unknown significance (35/94 patients) or no mutations detected in the 45 genes tested (26/94 patients). Mutation detection rates for targeted re-sequencing vs. whole exome were similar in both methods; however exome sequencing showed better distribution of reads and fewer exon dropouts. CONCLUSIONS Given that costs of highly parallel re-sequencing and whole exome sequencing are similar, and that exome sequencing now takes considerably less laboratory processing time than targeted re-sequencing, we recommend exome sequencing as the standard approach for molecular diagnostics of myopathies.
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Affiliation(s)
- Jaya Punetha
- Research Center for Genetic Medicine, Children's National Medical Center, Washington DC, USA.,Department of Integrative Systems Biology, The George Washington University School of Medicine and Health Sciences, Washington, DC, USA
| | - Akanchha Kesari
- Research Center for Genetic Medicine, Children's National Medical Center, Washington DC, USA
| | - Prech Uapinyoying
- Research Center for Genetic Medicine, Children's National Medical Center, Washington DC, USA.,Department of Integrative Systems Biology, The George Washington University School of Medicine and Health Sciences, Washington, DC, USA
| | - Mamta Giri
- Research Center for Genetic Medicine, Children's National Medical Center, Washington DC, USA
| | - Nigel F Clarke
- INMR, The Children's Hospital at Westmead & Discipline of Paediatrics and Child Health, University of Sydney, Sydney, Australia
| | - Leigh B Waddell
- INMR, The Children's Hospital at Westmead & Discipline of Paediatrics and Child Health, University of Sydney, Sydney, Australia
| | - Kathryn N North
- INMR, The Children's Hospital at Westmead & Discipline of Paediatrics and Child Health, University of Sydney, Sydney, Australia.,Murdoch Childrens Research Institute, Melbourne, Australia; Department of Paediatrics, Faculty of Medicine, University of Melbourne, Melbourne, Australia
| | - Roula Ghaoui
- INMR, The Children's Hospital at Westmead & Discipline of Paediatrics and Child Health, University of Sydney, Sydney, Australia
| | - Gina L O'Grady
- INMR, The Children's Hospital at Westmead & Discipline of Paediatrics and Child Health, University of Sydney, Sydney, Australia
| | - Emily C Oates
- INMR, The Children's Hospital at Westmead & Discipline of Paediatrics and Child Health, University of Sydney, Sydney, Australia
| | - Sarah A Sandaradura
- INMR, The Children's Hospital at Westmead & Discipline of Paediatrics and Child Health, University of Sydney, Sydney, Australia
| | - Carsten G Bönnemann
- National Institute of Neurological Disorders and Stroke/NIH, Porter Neuroscience Research Center, Bethesda, MD, USA
| | - Sandra Donkervoort
- National Institute of Neurological Disorders and Stroke/NIH, Porter Neuroscience Research Center, Bethesda, MD, USA
| | - Paul H Plotz
- National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Edward C Smith
- Department of Pediatrics, Division of Pediatric Neurology, Duke University Medical Center, Durham, NC, USA
| | - Carolina Tesi-Rocha
- Research Center for Genetic Medicine, Children's National Medical Center, Washington DC, USA
| | - Tulio E Bertorini
- Department of Neurology, The University of Tennessee Health Science Center, Memphis, TN, USA
| | - Mark A Tarnopolsky
- Departments of Pediatrics and Medicine, McMaster University, Neuromuscular Disease Clinic, Health Sciences Centre, ON, Canada
| | - Bernd Reitter
- Children's Hospital, Johannes Gutenberg University, Mainz, Germany
| | | | - Eric P Hoffman
- Research Center for Genetic Medicine, Children's National Medical Center, Washington DC, USA.,Department of Integrative Systems Biology, The George Washington University School of Medicine and Health Sciences, Washington, DC, USA
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91
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Wang L, Geist J, Grogan A, Hu LYR, Kontrogianni-Konstantopoulos A. Thick Filament Protein Network, Functions, and Disease Association. Compr Physiol 2018; 8:631-709. [PMID: 29687901 PMCID: PMC6404781 DOI: 10.1002/cphy.c170023] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Sarcomeres consist of highly ordered arrays of thick myosin and thin actin filaments along with accessory proteins. Thick filaments occupy the center of sarcomeres where they partially overlap with thin filaments. The sliding of thick filaments past thin filaments is a highly regulated process that occurs in an ATP-dependent manner driving muscle contraction. In addition to myosin that makes up the backbone of the thick filament, four other proteins which are intimately bound to the thick filament, myosin binding protein-C, titin, myomesin, and obscurin play important structural and regulatory roles. Consistent with this, mutations in the respective genes have been associated with idiopathic and congenital forms of skeletal and cardiac myopathies. In this review, we aim to summarize our current knowledge on the molecular structure, subcellular localization, interacting partners, function, modulation via posttranslational modifications, and disease involvement of these five major proteins that comprise the thick filament of striated muscle cells. © 2018 American Physiological Society. Compr Physiol 8:631-709, 2018.
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Affiliation(s)
- Li Wang
- Department of Biochemistry and Molecular Biology, University of Maryland, Baltimore, Maryland, USA
| | - Janelle Geist
- Department of Biochemistry and Molecular Biology, University of Maryland, Baltimore, Maryland, USA
| | - Alyssa Grogan
- Department of Biochemistry and Molecular Biology, University of Maryland, Baltimore, Maryland, USA
| | - Li-Yen R. Hu
- Department of Biochemistry and Molecular Biology, University of Maryland, Baltimore, Maryland, USA
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92
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Tasca G, Udd B. Hereditary myopathy with early respiratory failure (HMERF): Still rare, but common enough. Neuromuscul Disord 2018; 28:268-276. [DOI: 10.1016/j.nmd.2017.12.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Revised: 11/04/2017] [Accepted: 12/03/2017] [Indexed: 01/04/2023]
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93
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Carlisle C, Prill K, Pilgrim D. Chaperones and the Proteasome System: Regulating the Construction and Demolition of Striated Muscle. Int J Mol Sci 2017; 19:E32. [PMID: 29271938 PMCID: PMC5795982 DOI: 10.3390/ijms19010032] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2017] [Revised: 11/28/2017] [Accepted: 12/18/2017] [Indexed: 12/21/2022] Open
Abstract
Protein folding factors (chaperones) are required for many diverse cellular functions. In striated muscle, chaperones are required for contractile protein function, as well as the larger scale assembly of the basic unit of muscle, the sarcomere. The sarcomere is complex and composed of hundreds of proteins and the number of proteins and processes recognized to be regulated by chaperones has increased dramatically over the past decade. Research in the past ten years has begun to discover and characterize the chaperones involved in the assembly of the sarcomere at a rapid rate. Because of the dynamic nature of muscle, wear and tear damage is inevitable. Several systems, including chaperones and the ubiquitin proteasome system (UPS), have evolved to regulate protein turnover. Much of our knowledge of muscle development focuses on the formation of the sarcomere but recent work has begun to elucidate the requirement and role of chaperones and the UPS in sarcomere maintenance and disease. This review will cover the roles of chaperones in sarcomere assembly, the importance of chaperone homeostasis and the cooperation of chaperones and the UPS in sarcomere integrity and disease.
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Affiliation(s)
- Casey Carlisle
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada.
| | - Kendal Prill
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada.
| | - Dave Pilgrim
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada.
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94
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The histone code reader Spin1 controls skeletal muscle development. Cell Death Dis 2017; 8:e3173. [PMID: 29168801 PMCID: PMC5775400 DOI: 10.1038/cddis.2017.468] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Revised: 07/12/2017] [Accepted: 07/28/2017] [Indexed: 01/06/2023]
Abstract
While several studies correlated increased expression of the histone code reader Spin1 with tumor formation or growth, little is known about physiological functions of the protein. We generated Spin1M5 mice with ablation of Spin1 in myoblast precursors using the Myf5-Cre deleter strain. Most Spin1M5 mice die shortly after birth displaying severe sarcomere disorganization and necrosis. Surviving Spin1M5 mice are growth-retarded and exhibit the most prominent defects in soleus, tibialis anterior, and diaphragm muscle. Transcriptome analyses of limb muscle at embryonic day (E) 15.5, E16.5, and at three weeks of age provided evidence for aberrant fetal myogenesis and identified deregulated skeletal muscle (SkM) functional networks. Determination of genome-wide chromatin occupancy in primary myoblast revealed direct Spin1 target genes and suggested that deregulated basic helix-loop-helix transcription factor networks account for developmental defects in Spin1M5 fetuses. Furthermore, correlating histological and transcriptome analyses, we show that aberrant expression of titin-associated proteins, abnormal glycogen metabolism, and neuromuscular junction defects contribute to SkM pathology in Spin1M5 mice. Together, we describe the first example of a histone code reader controlling SkM development in mice, which hints at Spin1 as a potential player in human SkM disease.
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95
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Ehsan M, Jiang H, L Thomson K, Gehmlich K. When signalling goes wrong: pathogenic variants in structural and signalling proteins causing cardiomyopathies. J Muscle Res Cell Motil 2017; 38:303-316. [PMID: 29119312 PMCID: PMC5742121 DOI: 10.1007/s10974-017-9487-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Accepted: 10/28/2017] [Indexed: 12/20/2022]
Abstract
Cardiomyopathies are a diverse group of cardiac disorders with distinct phenotypes, depending on the proteins and pathways affected. A substantial proportion of cardiomyopathies are inherited and those will be the focus of this review article. With the wide application of high-throughput sequencing in the practice of clinical genetics, the roles of novel genes in cardiomyopathies are recognised. Here, we focus on a subgroup of cardiomyopathy genes [TTN, FHL1, CSRP3, FLNC and PLN, coding for Titin, Four and a Half LIM domain 1, Muscle LIM Protein, Filamin C and Phospholamban, respectively], which, despite their diverse biological functions, all have important signalling functions in the heart, suggesting that disturbances in signalling networks can contribute to cardiomyopathies.
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Affiliation(s)
- Mehroz Ehsan
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine and British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, UK
| | - He Jiang
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine and British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, UK
| | - Kate L Thomson
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine and British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, UK
| | - Katja Gehmlich
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine and British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, UK.
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96
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Laddach A, Gautel M, Fraternali F. TITINdb-a computational tool to assess titin's role as a disease gene. Bioinformatics 2017; 33:3482-3485. [PMID: 29077808 PMCID: PMC5860166 DOI: 10.1093/bioinformatics/btx424] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Revised: 06/15/2017] [Accepted: 07/03/2017] [Indexed: 01/22/2023] Open
Abstract
SUMMARY Large numbers of rare and unique titin missense variants have been discovered in both healthy and disease cohorts, thus the correct classification of variants as pathogenic or non-pathogenic has become imperative. Due to titin's large size (363 coding exons), current web applications are unable to map titin variants to domain structures. Here, we present a web application, TITINdb, which integrates titin structure, variant, sequence and isoform information, along with pre-computed predictions of the impact of non-synonymous single nucleotide variants, to facilitate the correct classification of titin variants. AVAILABILITY AND IMPLEMENTATION TITINdb can be freely accessed at http://fraternalilab.kcl.ac.uk/TITINdb. CONTACT franca.fraternali@kcl.ac.uk. SUPPLEMENTARY INFORMATION Supplementary data are available at Bioinformatics online.
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Affiliation(s)
- Anna Laddach
- Randall Division of Cell and Molecular Biophysics, King’s College London BHF Centre of Research Excellence, London, UK
| | - Mathias Gautel
- Randall Division of Cell and Molecular Biophysics, King’s College London BHF Centre of Research Excellence, London, UK
| | - Franca Fraternali
- Randall Division of Cell and Molecular Biophysics, King’s College London BHF Centre of Research Excellence, London, UK
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97
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Abstract
Nonischemic dilated cardiomyopathy (DCM) often has a genetic pathogenesis. Because of the large number of genes and alleles attributed to DCM, comprehensive genetic testing encompasses ever-increasing gene panels. Genetic diagnosis can help predict prognosis, especially with regard to arrhythmia risk for certain subtypes. Moreover, cascade genetic testing in family members can identify those who are at risk or with early stage disease, offering the opportunity for early intervention. This review will address diagnosis and management of DCM, including the role of genetic evaluation. We will also overview distinct genetic pathways linked to DCM and their pathogenetic mechanisms. Historically, cardiac morphology has been used to classify cardiomyopathy subtypes. Determining genetic variants is emerging as an additional adjunct to help further refine subtypes of DCM, especially where arrhythmia risk is increased, and ultimately contribute to clinical management.
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Affiliation(s)
- Elizabeth M McNally
- From the Center for Genetic Medicine, Northwestern University Feinberg School of Medicine, Chicago IL (E.M.M.); and Cardiovascular Institute, University of Colorado Anschutz Medical Campus, Aurora (L.M.).
| | - Luisa Mestroni
- From the Center for Genetic Medicine, Northwestern University Feinberg School of Medicine, Chicago IL (E.M.M.); and Cardiovascular Institute, University of Colorado Anschutz Medical Campus, Aurora (L.M.).
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98
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Eilbeck K, Quinlan A, Yandell M. Settling the score: variant prioritization and Mendelian disease. Nat Rev Genet 2017; 18:599-612. [PMID: 28804138 PMCID: PMC5935497 DOI: 10.1038/nrg.2017.52] [Citation(s) in RCA: 152] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
When investigating Mendelian disease using exome or genome sequencing, distinguishing disease-causing genetic variants from the multitude of candidate variants is a complex, multidimensional task. Many prioritization tools and online interpretation resources exist, and professional organizations have offered clinical guidelines for review and return of prioritization results. In this Review, we describe the strengths and weaknesses of widely used computational approaches, explain their roles in the diagnostic and discovery process and discuss how they can inform (and misinform) expert reviewers. We place variant prioritization in the wider context of gene prioritization, burden testing and genotype-phenotype association, and we discuss opportunities and challenges introduced by whole-genome sequencing.
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Affiliation(s)
- Karen Eilbeck
- Department of Biomedical Informatics, School of Medicine, University of Utah, 421 Wakara Way, Suite 120, Salt Lake City, Utah 84108, USA
| | - Aaron Quinlan
- Department of Biomedical Informatics, School of Medicine, University of Utah, 421 Wakara Way, Suite 120, Salt Lake City, Utah 84108, USA
- Department of Human Genetics, Eccles Institute of Human Genetics, School of Medicine, University of Utah, 15 S 2030 E, Salt Lake City, Utah 84112, USA
| | - Mark Yandell
- Department of Human Genetics, Eccles Institute of Human Genetics, School of Medicine, University of Utah, 15 S 2030 E, Salt Lake City, Utah 84112, USA
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99
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Shim SH, Kim JY, Sung SR, Park JE, Shin YJ, Shim SH, Cha DH. Prenatally diagnosed TTN mutation with repeated bilateral club foot by whole exome sequencing. BIOCHIP JOURNAL 2017. [DOI: 10.1007/s13206-017-1309-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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100
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Randazzo D, Pierantozzi E, Rossi D, Sorrentino V. The potential of obscurin as a therapeutic target in muscle disorders. Expert Opin Ther Targets 2017; 21:897-910. [DOI: 10.1080/14728222.2017.1361931] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Davide Randazzo
- Light Imaging Section, Office of Science and Technology, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda
| | - Enrico Pierantozzi
- Molecular Medicine Section, Department of Molecular and Developmental Medicine, University of Siena, Siena, Italy
| | - Daniela Rossi
- Molecular Medicine Section, Department of Molecular and Developmental Medicine, University of Siena, Siena, Italy
| | - Vincenzo Sorrentino
- Molecular Medicine Section, Department of Molecular and Developmental Medicine, University of Siena, Siena, Italy
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