1
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Perrin A, Métay C, Savarese M, Ben Yaou R, Demidov G, Nelson I, Solé G, Péréon Y, Bertini ES, Fattori F, D'Amico A, Ricci F, Ginsberg M, Seferian A, Boespflug-Tanguy O, Servais L, Chapon F, Lagrange E, Gaudon K, Bloch A, Ghanem R, Guyant-Maréchal L, Johari M, Van Goethem C, Fardeau M, Morales RJ, Genetti CA, Marttila M, Koenig M, Beggs AH, Udd B, Bonne G, Cossée M. Titin copy number variations associated with dominant inherited phenotypes. J Med Genet 2024; 61:369-377. [PMID: 37935568 PMCID: PMC10957311 DOI: 10.1136/jmg-2023-109473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Accepted: 10/18/2023] [Indexed: 11/09/2023]
Abstract
BACKGROUND Titinopathies are caused by mutations in the titin gene (TTN). Titin is the largest known human protein; its gene has the longest coding phase with 364 exons. Titinopathies are very complex neuromuscular pathologies due to the variable age of onset of symptoms, the great diversity of pathological and muscular impairment patterns (cardiac, skeletal muscle or mixed) and both autosomal dominant and recessive modes of transmission. Until now, only few CNVs in TTN have been reported without clear genotype-phenotype associations. METHODS Our study includes eight families with dominant titinopathies. We performed next-generation sequencing or comparative genomic hybridisation array analyses and found CNVs in the TTN gene. We characterised these CNVs by RNA sequencing (RNAseq) analyses in six patients' muscles and performed genotype-phenotype inheritance association study by combining the clinical and biological data of these eight families. RESULTS Seven deletion-type CNVs in the TTN gene were identified among these families. Genotype and RNAseq results showed that five deletions do not alter the reading frame and one is out-of-reading frame. The main phenotype identified was distal myopathy associated with contractures. The analysis of morphological, clinical and genetic data and imaging let us draw new genotype-phenotype associations of titinopathies. CONCLUSION Identifying TTN CNVs will further increase diagnostic sensitivity in these complex neuromuscular pathologies. Our cohort of patients enabled us to identify new deletion-type CNVs in the TTN gene, with unexpected autosomal dominant transmission. This is valuable in establishing new genotype-phenotype associations of titinopathies, mainly distal myopathy in most of the patients.
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Affiliation(s)
- Aurélien Perrin
- Laboratoire de Génétique Moléculaire, Centre Hospitalier Universitaire de Montpellier, Montpellier, France
- PhyMedExp, Université de Montpellier, INSERM, CNRS, Montpellier, France
| | - Corinne Métay
- Unité Fonctionnelle de Cardiogénétique et Myogénétique moléculaire et cellulaire, Centre de Génétique Moléculaire et Chromosomique, Groupe Hospitalier La Pitié-Salpêtrière-Charles Foix, Paris, France
- Sorbonne Université, INSERM, Institut de Myologie, Centre de Recherche en Myologie, Paris, France
| | - Marco Savarese
- Tampere Neuromuscular Center, Folkhälsan Research Center, Helsinki, Finland
| | - Rabah Ben Yaou
- Sorbonne Université, INSERM, Institut de Myologie, Centre de Recherche en Myologie, Paris, France
| | - German Demidov
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, Tubingen, Germany
| | - Isabelle Nelson
- Sorbonne Université, INSERM, Institut de Myologie, Centre de Recherche en Myologie, Paris, France
| | - Guilhem Solé
- CHU de Bordeaux, AOC National Reference Center for Neuromuscular Disorders, Bordeaux, France
| | - Yann Péréon
- Department of Clinical Neurophysiology, Reference Centre for Neuromuscular Diseases AOC, Filnemus, Euro-NMD, CHU Nantes, Nantes Université, Place Alexis-Ricordeau, Nantes, France
| | - Enrico Silvio Bertini
- Unit of Muscular and Neurodegenerative Disorders, Bambino Gesù Children Research Hospital, IRCCS, Rome, Italy
| | - Fabiana Fattori
- Unit of Muscular and Neurodegenerative Disorders, Bambino Gesù Children Research Hospital, IRCCS, Rome, Italy
| | - Adele D'Amico
- Unit of Muscular and Neurodegenerative Disorders, Bambino Gesù Children Research Hospital, IRCCS, Rome, Italy
| | - Federica Ricci
- Division of Child and Adolescent Neuropsychiatry, University of Turin, Turin, Italy
| | - Mira Ginsberg
- Department of Pediatric Neurology, Wolfson Medical Center, Holon, Israel
| | | | - Odile Boespflug-Tanguy
- Institut I-MOTION, Hôpital Armand Trousseau, Paris, France
- UMR 1141, INSERM, NeuroDiderot Université Paris Cité and APHP, Neuropédiatrie, French Reference Center for Leukodystrophies, LEUKOFRANCE, Hôpital Robert Debré, Paris, France
| | - Laurent Servais
- Institut I-MOTION, Hôpital Armand Trousseau, Paris, France
- MDUK Oxford Neuromuscular Centre & NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford, UK
- Neuromuscular Reference Center, Division of Paediatrics, University and Hospital University of Liège, Liège, Belgium
| | - Françoise Chapon
- Département de pathologie, Centre de Compétence des Maladies Neuromusculaires, Centre Hospitalier Universitaire de Caen, Caen, France
| | - Emmeline Lagrange
- Centre de Compétences des Maladies Neuro Musculaires, Centre Hospitalier Universitaire Grenoble Alpes, Grenoble, France
| | - Karen Gaudon
- Unité Fonctionnelle de Cardiogénétique et Myogénétique moléculaire et cellulaire, Centre de Génétique Moléculaire et Chromosomique, Groupe Hospitalier La Pitié-Salpêtrière-Charles Foix, Paris, France
| | - Adrien Bloch
- Unité Fonctionnelle de Cardiogénétique et Myogénétique moléculaire et cellulaire, Centre de Génétique Moléculaire et Chromosomique, Groupe Hospitalier La Pitié-Salpêtrière-Charles Foix, Paris, France
| | - Robin Ghanem
- Unité Fonctionnelle de Cardiogénétique et Myogénétique moléculaire et cellulaire, Centre de Génétique Moléculaire et Chromosomique, Groupe Hospitalier La Pitié-Salpêtrière-Charles Foix, Paris, France
| | | | - Mridul Johari
- Tampere Neuromuscular Center, Folkhälsan Research Center, Helsinki, Finland
- Harry Perkins Institute of Medical Research, Centre for Medical Research, University of Western Australia, Nedlands, Western Australia, Australia
| | - Charles Van Goethem
- Laboratoire de Génétique Moléculaire, Centre Hospitalier Universitaire de Montpellier, Montpellier, France
- Montpellier BioInformatique pour le Diagnostic Clinique (MOBIDIC), Plateau de Médecine Moléculaire et Génomique (PMMG), CHU Montpellier, Montpellier, France
| | - Michel Fardeau
- Sorbonne Université, INSERM, Institut de Myologie, Centre de Recherche en Myologie, Paris, France
| | - Raul Juntas Morales
- Department of Neurology, Hospital Universitario Vall d'Hebron, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Casie A Genetti
- Division of Genetics and Genomics, The Manton Center for Orphan Disease Research, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Minttu Marttila
- Division of Genetics and Genomics, The Manton Center for Orphan Disease Research, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
- HiLIFE Helsinki Institute of Life Science, Tukholmankatu 8, FI-00014, University of Helsinki, Helsinki, Finland
| | - Michel Koenig
- Laboratoire de Génétique Moléculaire, Centre Hospitalier Universitaire de Montpellier, Montpellier, France
- PhyMedExp, Université de Montpellier, INSERM, CNRS, Montpellier, France
| | - Alan H Beggs
- Division of Genetics and Genomics, The Manton Center for Orphan Disease Research, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Bjarne Udd
- Tampere Neuromuscular Center, Folkhälsan Research Center, Helsinki, Finland
| | - Gisèle Bonne
- Sorbonne Université, INSERM, Institut de Myologie, Centre de Recherche en Myologie, Paris, France
| | - Mireille Cossée
- Laboratoire de Génétique Moléculaire, Centre Hospitalier Universitaire de Montpellier, Montpellier, France
- PhyMedExp, Université de Montpellier, INSERM, CNRS, Montpellier, France
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2
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Perrin A, Juntas Morales R, Chapon F, Thèze C, Lacourt D, Pégeot H, Uro‐Coste E, Giovannini D, Leboucq N, Mallaret M, Lagrange E, Rigau V, Gaudon K, Richard P, Koenig M, Métay C, Cossée M. Novel dominant distal titinopathy phenotype associated with copy number variation. Ann Clin Transl Neurol 2021; 8:1906-1912. [PMID: 34312993 PMCID: PMC8419403 DOI: 10.1002/acn3.51434] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 06/28/2021] [Accepted: 07/12/2021] [Indexed: 01/27/2023] Open
Abstract
The aim of this study was to analyze patients from two distinct families with a novel distal titinopathy phenotype associated with exactly the same CNV in the TTN gene. We used an integrated strategy combining deep phenotyping and complete molecular analyses in patients. The CNV is the most proximal out-of-frame TTN variant reported and leads to aberrant splicing transcripts leading to a frameshift. In this case, the dominant effect would be due to dominant-negative and/or haploinsufficiency. Few CNV in TTN have been reported to date. Our data represent a novel phenotype-genotype association and provides hypotheses for its dominant effects.
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Affiliation(s)
- Aurélien Perrin
- Laboratoire de Génétique MoléculaireCentre Hospitalier Universitaire de MontpellierMontpellierFrance
- PhyMedExpUniversité de MontpellierINSERMCNRSMontpellierFrance
| | - Raul Juntas Morales
- Laboratoire de Génétique MoléculaireCentre Hospitalier Universitaire de MontpellierMontpellierFrance
- Service de NeurologieCentre de Référence des Maladies Neuromusculaires AOC (Atlantique‐Occitanie‐Caraïbe) Centre Hospitalier Universitaire de MontpellierMontpellierFrance
| | - Françoise Chapon
- Département de pathologieCentre de Compétence des Maladies NeuromusculairesCentre Hospitalier Universitaire de CaenCaenFrance
| | - Corinne Thèze
- Laboratoire de Génétique MoléculaireCentre Hospitalier Universitaire de MontpellierMontpellierFrance
| | - Delphine Lacourt
- Laboratoire de Génétique MoléculaireCentre Hospitalier Universitaire de MontpellierMontpellierFrance
| | - Henri Pégeot
- Laboratoire de Génétique MoléculaireCentre Hospitalier Universitaire de MontpellierMontpellierFrance
| | - Emmanuelle Uro‐Coste
- Département d’Anatomie et Cytologie PathologiquesCentre Hospitalier Universitaire ToulouseToulouseFrance
| | - Diane Giovannini
- Service d’Anatomie et de Cytologie PathologiquesCHU Grenoble‐AlpesGrenobleFrance
| | - Nicolas Leboucq
- Service de NeuroradiologieCentre Hospitalier Universitaire de MontpellierMontpellier34090France
| | - Martial Mallaret
- Centre de Compétences des Maladies Neuro MusculairesCentre Hospitalier Universitaire Grenoble AlpesGrenobleFrance
| | - Emmeline Lagrange
- Centre de Compétences des Maladies Neuro MusculairesCentre Hospitalier Universitaire Grenoble AlpesGrenobleFrance
| | - Valérie Rigau
- Département de PathologieCentre Hospitalier Universitaire MontpellierMontpellierFrance
| | - Karen Gaudon
- Unité Fonctionnelle de Cardiogénétique et Myogénétique moleculaire et cellulaireCentre de Génétique Moléculaire et Chromosomique et INSERM UMRS 974Institut de MyologieGroupe Hospitalier La Pitié‐Salpêtrière‐Charles FoixParisINSERMUMRS1166UPMC Paris 6ParisFrance
| | - Pascale Richard
- Unité Fonctionnelle de Cardiogénétique et Myogénétique moleculaire et cellulaireCentre de Génétique Moléculaire et Chromosomique et INSERM UMRS 974Institut de MyologieGroupe Hospitalier La Pitié‐Salpêtrière‐Charles FoixParisINSERMUMRS1166UPMC Paris 6ParisFrance
| | - Michel Koenig
- Laboratoire de Génétique MoléculaireCentre Hospitalier Universitaire de MontpellierMontpellierFrance
- PhyMedExpUniversité de MontpellierINSERMCNRSMontpellierFrance
| | - Corinne Métay
- Unité Fonctionnelle de Cardiogénétique et Myogénétique moleculaire et cellulaireCentre de Génétique Moléculaire et Chromosomique et INSERM UMRS 974Institut de MyologieGroupe Hospitalier La Pitié‐Salpêtrière‐Charles FoixParisINSERMUMRS1166UPMC Paris 6ParisFrance
| | - Mireille Cossée
- Laboratoire de Génétique MoléculaireCentre Hospitalier Universitaire de MontpellierMontpellierFrance
- PhyMedExpUniversité de MontpellierINSERMCNRSMontpellierFrance
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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: 8] [Impact Index Per Article: 2.7] [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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4
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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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5
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Sasaki R, Ohta Y, Tadokoro K, Matsumoto N, Nomura E, Omote Y, Takemoto M, Hishikawa N, Yamashita T, Kumutpongpanich T, Nishino I, Abe K. TTN missense variants in two siblings with asymmetric facial and limb weakness. J Neurol Sci 2020; 415:116885. [PMID: 32464347 DOI: 10.1016/j.jns.2020.116885] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Revised: 04/30/2020] [Accepted: 05/04/2020] [Indexed: 11/19/2022]
Affiliation(s)
- Ryo Sasaki
- Department of Neurology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 2-5-1 Shikata-cho, Kita-ku, Okayama 700-8558, Japan
| | - Yasuyuki Ohta
- Department of Neurology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 2-5-1 Shikata-cho, Kita-ku, Okayama 700-8558, Japan
| | - Koh Tadokoro
- Department of Neurology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 2-5-1 Shikata-cho, Kita-ku, Okayama 700-8558, Japan
| | - Namiko Matsumoto
- Department of Neurology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 2-5-1 Shikata-cho, Kita-ku, Okayama 700-8558, Japan
| | - Emi Nomura
- Department of Neurology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 2-5-1 Shikata-cho, Kita-ku, Okayama 700-8558, Japan
| | - Yoshio Omote
- Department of Neurology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 2-5-1 Shikata-cho, Kita-ku, Okayama 700-8558, Japan
| | - Mami Takemoto
- Department of Neurology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 2-5-1 Shikata-cho, Kita-ku, Okayama 700-8558, Japan
| | - Nozomi Hishikawa
- Department of Neurology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 2-5-1 Shikata-cho, Kita-ku, Okayama 700-8558, Japan
| | - Toru Yamashita
- Department of Neurology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 2-5-1 Shikata-cho, Kita-ku, Okayama 700-8558, Japan
| | - Theerawat Kumutpongpanich
- Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry (NCNP), 4-1-1 Ogawahigashi-cho, Kodaira, Tokyo 187-8502, Japan
| | - Ichizo Nishino
- Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry (NCNP), 4-1-1 Ogawahigashi-cho, Kodaira, Tokyo 187-8502, Japan
| | - Koji Abe
- Department of Neurology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 2-5-1 Shikata-cho, Kita-ku, Okayama 700-8558, Japan.
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6
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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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