51
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Sewry CA, Wallgren-Pettersson C. Myopathology in congenital myopathies. Neuropathol Appl Neurobiol 2018; 43:5-23. [PMID: 27976420 DOI: 10.1111/nan.12369] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Accepted: 12/03/2016] [Indexed: 12/18/2022]
Abstract
Congenital myopathies are clinically and genetically a heterogeneous group of early onset neuromuscular disorders, characterized by hypotonia and muscle weakness. Clinical severity and age of onset are variable. Many patients are severely affected at birth while others have a milder, moderately progressive or nonprogressive phenotype. Respiratory weakness is a major clinical aspect that requires regular monitoring. Causative mutations in several genes have been identified that are inherited in a dominant, recessive or X-linked manner, or arise de novo. Muscle biopsies show characteristic pathological features such as nemaline rods/bodies, cores, central nuclei or caps. Small type 1 fibres expressing slow myosin are a common feature and may sometimes be the only abnormality. Small cores (minicores) devoid of mitochondria and areas showing variable myofibrillar disruption occur in several neuromuscular disorders including several forms of congenital myopathy. Muscle biopsies can also show more than one structural defect. There is considerable clinical, pathological and genetic overlap with mutations in one gene resulting in more than one pathological feature, and the same pathological feature being associated with defects in more than one gene. Increasing application of whole exome sequencing is broadening the clinical and pathological spectra in congenital myopathies, but pathology still has a role in clarifying the pathogenicity of gene variants as well as directing molecular analysis.
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Affiliation(s)
- C A Sewry
- Dubowitz Neuromuscular Centre, UCL Institute of Child Health and Great Ormond Street Hospital for Children, London, UK.,Wolfson Centre for Inherited Neuromuscular Diseases, RJAH Orthopaedic Hospital, Oswestry, UK
| | - C Wallgren-Pettersson
- The Folkhälsan Institute of Genetics and the Department of Medical and Clinical Genetics, University of Helsinki, Helsinki, Finland
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52
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Nilipour Y, Nafissi S, Tjust AE, Ravenscroft G, Hossein Nejad Nedai H, Taylor RL, Varasteh V, Pedrosa Domellöf F, Zangi M, Tonekaboni SH, Olivé M, Kiiski K, Sagath L, Davis MR, Laing NG, Tajsharghi H. Ryanodine receptor type 3 (RYR3) as a novel gene associated with a myopathy with nemaline bodies. Eur J Neurol 2018; 25:841-847. [PMID: 29498452 DOI: 10.1111/ene.13607] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Accepted: 02/26/2018] [Indexed: 12/01/2022]
Abstract
BACKGROUND AND PURPOSE Nemaline myopathy (NEM) has been associated with mutations in 12 genes to date. However, for some patients diagnosed with NEM, definitive mutations are not identified in the known genes, suggesting that there are other genes involved. This study describes compound heterozygosity for rare variants in ryanodine receptor type 3 (RYR3) gene in one such patient. METHODS AND RESULTS Clinical examination of the patient at 22 years of age revealed a long narrow face, high arched palate and bilateral facial weakness. She had proximal weakness in all four limbs, mild scapular winging but no scoliosis. Muscle biopsy revealed wide variation in fibre size with type 1 fibre predominance and atrophy. Abundant nemaline bodies were located in perinuclear and subsarcolemmal areas, and within the cytoplasm. No likely pathogenic mutations in known NEM genes were identified. Copy number variation in known NEM genes was excluded by NEM-targeted comparative genomic hybridization array. Next-generation sequencing revealed compound heterozygous missense variants in the RYR3 gene. RYR3 transcripts are expressed in human fetal and adult skeletal muscle as well as in human brain and cauda equina samples. Immunofluorescence of human skeletal muscle revealed a 'single-row' appearance of RYR3, interspersed between the 'double rows' of ryanodine receptor type 1 (RYR1) at each A-I junction. CONCLUSION The results suggest that variants in RYR3 may cause a recessive muscle disease with pathological features including nemaline bodies. We characterize the expression pattern of RYR3 in human skeletal muscle and brain, and the subcellular localization of RYR1 and RYR3 in human skeletal muscle.
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Affiliation(s)
- Y Nilipour
- Pediatric Pathology Research Centre, Mofid Children's Hospital, Shahid Beheshti University of Medical Sciences, Tehran
| | - S Nafissi
- Department of Neurology, Tehran University of Medical Sciences, Tehran, Iran
| | - A E Tjust
- Department of Integrative Medical Biology, Umeå University, Umeå.,Department of Clinical Sciences, Umeå University, Umeå, Sweden
| | - G Ravenscroft
- Centre for Medical Research, University of Western Australia and Harry Perkins Institute for Medical Research, Nedlands, WA, Australia
| | | | - R L Taylor
- Centre for Medical Research, University of Western Australia and Harry Perkins Institute for Medical Research, Nedlands, WA, Australia
| | - V Varasteh
- Department of Pathology, Shahid Beheshti University of Medical Sciences, Tehran
| | - F Pedrosa Domellöf
- Department of Integrative Medical Biology, Umeå University, Umeå.,Department of Clinical Sciences, Umeå University, Umeå, Sweden
| | - M Zangi
- Tracheal Diseases Research Center (TDRC), National Research Institute of Tuberculosis and Lung Diseases (NRITLD), Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - S H Tonekaboni
- Pediatric Pathology Research Centre, Mofid Children's Hospital, Shahid Beheshti University of Medical Sciences, Tehran
| | - M Olivé
- Department of Pathology and Neuromuscular Unit, IDIBELL-Hospital de Bellvitge, Barcelona, Spain
| | - K Kiiski
- Department of Medical and Clinical Genetics, Folkhälsan Institute of Genetics, Medicum, University of Helsinki, Helsinki, Finland
| | - L Sagath
- Department of Medical and Clinical Genetics, Folkhälsan Institute of Genetics, Medicum, University of Helsinki, Helsinki, Finland
| | - M R Davis
- Department of Diagnostic Genomics, Pathwest, QEII Medical Centre, Nedlands, WA, Australia
| | - N G Laing
- Centre for Medical Research, University of Western Australia and Harry Perkins Institute for Medical Research, Nedlands, WA, Australia
| | - H Tajsharghi
- Centre for Medical Research, University of Western Australia and Harry Perkins Institute for Medical Research, Nedlands, WA, Australia.,Division of Biomedicine, School of Health and Education, University of Skövde, Skövde, Sweden
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53
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Fattori F, Fiorillo C, Rodolico C, Tasca G, Verardo M, Bellacchio E, Pizzi S, Ciolfi A, Fagiolari G, Lupica A, Broda P, Pedemonte M, Moggio M, Bruno C, Tartaglia M, Bertini E, D'Amico A. Expanding the histopathological spectrum of CFL2
-related myopathies. Clin Genet 2018; 93:1234-1239. [DOI: 10.1111/cge.13240] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Revised: 02/13/2018] [Accepted: 02/14/2018] [Indexed: 11/29/2022]
Affiliation(s)
- F. Fattori
- Unit of Neuromuscular and Neurodegenerative Disorders, Genetics and Rare Diseases Research Division; Bambino Gesù Children's Hospital; Rome Italy
| | - C. Fiorillo
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics; Maternal and Child Health, University of Genoa; Genoa Italy
| | - C. Rodolico
- Department of Clinical and Experimental Medicine; University of Messina; Messina Italy
| | - G. Tasca
- Istituto di Neurologia; Università Cattolica del Sacro Cuore, Fondazione Policlinico Universitario "A. Gemelli"; Rome Italy
| | - M. Verardo
- Unit of Neuromuscular and Neurodegenerative Disorders, Genetics and Rare Diseases Research Division; Bambino Gesù Children's Hospital; Rome Italy
| | - E. Bellacchio
- Molecular Genetics and Functional Genomics, Genetics and Rare Diseases Research Division; Bambino Gesù Children's Hospital; Rome Italy
| | - S. Pizzi
- Molecular Genetics and Functional Genomics, Genetics and Rare Diseases Research Division; Bambino Gesù Children's Hospital; Rome Italy
| | - A. Ciolfi
- Molecular Genetics and Functional Genomics, Genetics and Rare Diseases Research Division; Bambino Gesù Children's Hospital; Rome Italy
| | - G. Fagiolari
- Neuromuscular and Rare Disease Unit, Department of Neuroscience, IRCCS Foundation Ca' Granda Ospedale Maggiore Policlinico; University of Milan; Milan Italy
| | - A. Lupica
- Department of Clinical and Experimental Medicine; University of Messina; Messina Italy
| | - P. Broda
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics; Maternal and Child Health, University of Genoa; Genoa Italy
| | - M. Pedemonte
- Center of Myology and Neurodegenerative Disease; Istituto Giannina Gaslini; Genova Italy
| | - M. Moggio
- Neuromuscular and Rare Disease Unit, Department of Neuroscience, IRCCS Foundation Ca' Granda Ospedale Maggiore Policlinico; University of Milan; Milan Italy
| | - C. Bruno
- Center of Myology and Neurodegenerative Disease; Istituto Giannina Gaslini; Genova Italy
| | - M. Tartaglia
- Molecular Genetics and Functional Genomics, Genetics and Rare Diseases Research Division; Bambino Gesù Children's Hospital; Rome Italy
| | - E. Bertini
- Unit of Neuromuscular and Neurodegenerative Disorders, Genetics and Rare Diseases Research Division; Bambino Gesù Children's Hospital; Rome Italy
- Molecular Genetics and Functional Genomics, Genetics and Rare Diseases Research Division; Bambino Gesù Children's Hospital; Rome Italy
| | - A. D'Amico
- Unit of Neuromuscular and Neurodegenerative Disorders, Genetics and Rare Diseases Research Division; Bambino Gesù Children's Hospital; Rome Italy
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54
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Joureau B, de Winter JM, Conijn S, Bogaards SJP, Kovacevic I, Kalganov A, Persson M, Lindqvist J, Stienen GJM, Irving TC, Ma W, Yuen M, Clarke NF, Rassier DE, Malfatti E, Romero NB, Beggs AH, Ottenheijm CAC. Dysfunctional sarcomere contractility contributes to muscle weakness in ACTA1-related nemaline myopathy (NEM3). Ann Neurol 2018; 83:269-282. [PMID: 29328520 DOI: 10.1002/ana.25144] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 01/10/2018] [Accepted: 01/10/2018] [Indexed: 01/23/2023]
Abstract
OBJECTIVE Nemaline myopathy (NM) is one of the most common congenital nondystrophic myopathies and is characterized by muscle weakness, often from birth. Mutations in ACTA1 are a frequent cause of NM (ie, NEM3). ACTA1 encodes alpha-actin 1, the main constituent of the sarcomeric thin filament. The mechanisms by which mutations in ACTA1 contribute to muscle weakness in NEM3 are incompletely understood. We hypothesized that sarcomeric dysfunction contributes to muscle weakness in NEM3 patients. METHODS To test this hypothesis, we performed contractility measurements in individual muscle fibers and myofibrils obtained from muscle biopsies of 14 NEM3 patients with different ACTA1 mutations. To identify the structural basis for impaired contractility, low angle X-ray diffraction and stimulated emission-depletion microscopy were applied. RESULTS Our findings reveal that muscle fibers of NEM3 patients display a reduced maximal force-generating capacity, which is caused by dysfunctional sarcomere contractility in the majority of patients, as revealed by contractility measurements in myofibrils. Low angle X-ray diffraction and stimulated emission-depletion microscopy indicate that dysfunctional sarcomere contractility in NEM3 patients involves a lower number of myosin heads binding to actin during muscle activation. This lower number is not the result of reduced thin filament length. Interestingly, the calcium sensitivity of force is unaffected in some patients, but decreased in others. INTERPRETATION Dysfunctional sarcomere contractility is an important contributor to muscle weakness in the majority of NEM3 patients. This information is crucial for patient stratification in future clinical trials. Ann Neurol 2018;83:269-282.
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Affiliation(s)
- Barbara Joureau
- Department of Physiology, VU University Medical Center Amsterdam, Amsterdam, the Netherlands
| | | | - Stefan Conijn
- Department of Physiology, VU University Medical Center Amsterdam, Amsterdam, the Netherlands
| | - Sylvia J P Bogaards
- Department of Physiology, VU University Medical Center Amsterdam, Amsterdam, the Netherlands
| | - Igor Kovacevic
- Department of Physiology, VU University Medical Center Amsterdam, Amsterdam, the Netherlands
| | - Albert Kalganov
- Department of Kinesiology and Physical Education, McGill University, Montreal, Quebec, Canada
| | - Malin Persson
- Department of Kinesiology and Physical Education, McGill University, Montreal, Quebec, Canada.,Department of Physiology and Pharmacology, Karolinska Institute, Stockholm, Sweden
| | - Johan Lindqvist
- Department of Molecular and Cellular Biology and Molecular Cardiovascular Research Program, University of Arizona, Tucson, AZ
| | - Ger J M Stienen
- Department of Physiology, VU University Medical Center Amsterdam, Amsterdam, the Netherlands
| | - Thomas C Irving
- Biophysics Collaborative Access Team, Center for Synchrotron Radiation Research and Instrumentation, and Department of Biological Sciences, Illinois Institute of Technology, Chicago, IL
| | - Weikang Ma
- Biophysics Collaborative Access Team, Center for Synchrotron Radiation Research and Instrumentation, and Department of Biological Sciences, Illinois Institute of Technology, Chicago, IL
| | - Michaela Yuen
- Department of Physiology, VU University Medical Center Amsterdam, Amsterdam, the Netherlands.,Institute for Neuroscience and Muscle Research, Children's Hospital at Westmead, Westmead, New South Wales, Australia.,Discipline of Pediatrics and Child Health, University of Sydney, Sydney, New South Wales, Australia
| | - Nigel F Clarke
- Institute for Neuroscience and Muscle Research, Children's Hospital at Westmead, Westmead, New South Wales, Australia.,Discipline of Pediatrics and Child Health, University of Sydney, Sydney, New South Wales, Australia
| | - Dilson E Rassier
- Department of Kinesiology and Physical Education, McGill University, Montreal, Quebec, Canada
| | - Edoardo Malfatti
- Pierre and Marie Curie University/University of Paris VI, Sorbonne Universities, National Institute of Health and Medical Research UMRS974, National Center for Scientific Research FRE3617, Center for Research in Myology, Pitié-Salpêtrière Hospital Group, Paris, France
| | - Norma B Romero
- Pierre and Marie Curie University/University of Paris VI, Sorbonne Universities, National Institute of Health and Medical Research UMRS974, National Center for Scientific Research FRE3617, Center for Research in Myology, Pitié-Salpêtrière Hospital Group, Paris, France
| | - Alan H Beggs
- Division of Genetics and Genomics, Manton Center for Orphan Disease Research, Boston Children's Hospital, Harvard Medical School, Boston, MA
| | - Coen A C Ottenheijm
- Department of Physiology, VU University Medical Center Amsterdam, Amsterdam, the Netherlands.,Department of Molecular and Cellular Biology and Molecular Cardiovascular Research Program, University of Arizona, Tucson, AZ
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55
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Congenital myopathies: disorders of excitation-contraction coupling and muscle contraction. Nat Rev Neurol 2018; 14:151-167. [PMID: 29391587 DOI: 10.1038/nrneurol.2017.191] [Citation(s) in RCA: 177] [Impact Index Per Article: 29.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The congenital myopathies are a group of early-onset, non-dystrophic neuromuscular conditions with characteristic muscle biopsy findings, variable severity and a stable or slowly progressive course. Pronounced weakness in axial and proximal muscle groups is a common feature, and involvement of extraocular, cardiorespiratory and/or distal muscles can implicate specific genetic defects. Central core disease (CCD), multi-minicore disease (MmD), centronuclear myopathy (CNM) and nemaline myopathy were among the first congenital myopathies to be reported, and they still represent the main diagnostic categories. However, these entities seem to belong to a much wider phenotypic spectrum. To date, congenital myopathies have been attributed to mutations in over 20 genes, which encode proteins implicated in skeletal muscle Ca2+ homeostasis, excitation-contraction coupling, thin-thick filament assembly and interactions, and other mechanisms. RYR1 mutations are the most frequent genetic cause, and CCD and MmD are the most common subgroups. Next-generation sequencing has vastly improved mutation detection and has enabled the identification of novel genetic backgrounds. At present, management of congenital myopathies is largely supportive, although new therapeutic approaches are reaching the clinical trial stage.
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56
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Armes JE, Williams M, Price G, Wallis T, Gallagher R, Matsika A, Joy C, Galea M, Gardener G, Leach R, Swagemakers SM, Tearle R, Stubbs A, Harraway J, van der Spek PJ, Venter DJ. Application of Whole Genome Sequencing Technology in the Investigation of Genetic Causes of Fetal, Perinatal, and Early Infant Death. Pediatr Dev Pathol 2018. [PMID: 28641477 DOI: 10.1177/1093526617715528] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Death in the fetal, perinatal, and early infant age-group has a multitude of causes, a proportion of which is presumed to be genetic. Defining a specific genetic aberration leading to the death is problematic at this young age, due to limited phenotype-genotype correlation inherent in the underdeveloped phenotype, the inability to assess certain phenotypic traits after death, and the problems of dealing with rare disorders. In this study, our aim was to increase the yield of identification of a defined genetic cause of an early death. Therefore, we employed whole genome sequencing and bioinformatic filtering techniques as a comprehensive, unbiased genetic investigation into 16 fetal, perinatal, and early infant deaths, which had undergone a full autopsy. A likely genetic cause was identified in two cases (in genes; COL2A1 and RYR1) and a speculative genetic cause in a further six cases (in genes: ARHGAP35, BBS7, CASZ1, CRIM1, DHCR7, HADHB, HAPLN3, HSPG2, MYO18B, and SRGAP2). This investigation indicates that whole genome sequencing is a significantly enabling technology when determining genetic causes of early death.
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Affiliation(s)
- Jane E Armes
- 1 Department of Pathology, Mater Health, South Brisbane, Queensland, Australia.,2 Mater Research Institute, University of Queensland, Queensland, Australia.,3 School of Medicine, University of Queensland, Queensland, Australia
| | - Mark Williams
- 1 Department of Pathology, Mater Health, South Brisbane, Queensland, Australia.,2 Mater Research Institute, University of Queensland, Queensland, Australia
| | - Gareth Price
- 1 Department of Pathology, Mater Health, South Brisbane, Queensland, Australia
| | - Tristan Wallis
- 1 Department of Pathology, Mater Health, South Brisbane, Queensland, Australia
| | - Renee Gallagher
- 1 Department of Pathology, Mater Health, South Brisbane, Queensland, Australia
| | - Admire Matsika
- 1 Department of Pathology, Mater Health, South Brisbane, Queensland, Australia
| | - Christopher Joy
- 1 Department of Pathology, Mater Health, South Brisbane, Queensland, Australia
| | - Melanie Galea
- 1 Department of Pathology, Mater Health, South Brisbane, Queensland, Australia
| | - Glenn Gardener
- 2 Mater Research Institute, University of Queensland, Queensland, Australia.,4 Centre for Maternal Fetal Medicine, Mater Health, South Brisbane, Queensland, Australia
| | - Rick Leach
- 5 Complete Genomics Inc, Mountain View, California
| | | | - Rick Tearle
- 5 Complete Genomics Inc, Mountain View, California.,7 Davies Research Centre, School of Animal and Veterinary Sciences, Faculty of Sciences, University of Adelaide, Roseworthy, South Australia, Australia
| | - Andrew Stubbs
- 6 Department of Bioinformatics, Erasmus MC, Rotterdam, The Netherlands
| | - James Harraway
- 1 Department of Pathology, Mater Health, South Brisbane, Queensland, Australia
| | - Peter J van der Spek
- 6 Department of Bioinformatics, Erasmus MC, Rotterdam, The Netherlands.,8 Department of Pathology, Erasmus MC, Rotterdam, The Netherlands
| | - Deon J Venter
- 1 Department of Pathology, Mater Health, South Brisbane, Queensland, Australia.,2 Mater Research Institute, University of Queensland, Queensland, Australia.,3 School of Medicine, University of Queensland, Queensland, Australia
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57
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Reber S, Mechtersheimer J, Nasif S, Benitez JA, Colombo M, Domanski M, Jutzi D, Hedlund E, Ruepp MD. CRISPR-Trap: a clean approach for the generation of gene knockouts and gene replacements in human cells. Mol Biol Cell 2017; 29:75-83. [PMID: 29167381 PMCID: PMC5909934 DOI: 10.1091/mbc.e17-05-0288] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Revised: 10/27/2017] [Accepted: 11/16/2017] [Indexed: 01/08/2023] Open
Abstract
CRISPR/Cas9-based genome editing offers the possibility to knock out almost any gene of interest in an affordable and simple manner. The most common strategy is the introduction of a frameshift into the open reading frame (ORF) of the target gene which truncates the coding sequence (CDS) and targets the corresponding transcript for degradation by nonsense-mediated mRNA decay (NMD). However, we show that transcripts containing premature termination codons (PTCs) are not always degraded efficiently and can generate C-terminally truncated proteins which might have residual or dominant negative functions. Therefore, we recommend an alternative approach for knocking out genes, which combines CRISPR/Cas9 with gene traps (CRISPR-Trap) and is applicable to ∼50% of all spliced human protein-coding genes and a large subset of lncRNAs. CRISPR-Trap completely prevents the expression of the ORF and avoids expression of C-terminal truncated proteins. We demonstrate the feasibility of CRISPR-Trap by utilizing it to knock out several genes in different human cell lines. Finally, we also show that this approach can be used to efficiently generate gene replacements allowing for modulation of protein levels for otherwise lethal knockouts (KOs). Thus, CRISPR-Trap offers several advantages over conventional KO approaches and allows for generation of clean CRISPR/Cas9-based KOs.
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Affiliation(s)
- Stefan Reber
- Department of Chemistry and Biochemistry, University of Bern, CH-3012 Bern, Switzerland.,Graduate School for Cellular and Biomedical Sciences, University of Bern, CH-3012 Bern, Switzerland
| | - Jonas Mechtersheimer
- Department of Chemistry and Biochemistry, University of Bern, CH-3012 Bern, Switzerland.,Graduate School for Cellular and Biomedical Sciences, University of Bern, CH-3012 Bern, Switzerland
| | - Sofia Nasif
- Department of Chemistry and Biochemistry, University of Bern, CH-3012 Bern, Switzerland
| | | | - Martino Colombo
- Department of Chemistry and Biochemistry, University of Bern, CH-3012 Bern, Switzerland.,Graduate School for Cellular and Biomedical Sciences, University of Bern, CH-3012 Bern, Switzerland
| | - Michal Domanski
- Department of Chemistry and Biochemistry, University of Bern, CH-3012 Bern, Switzerland
| | - Daniel Jutzi
- Department of Chemistry and Biochemistry, University of Bern, CH-3012 Bern, Switzerland.,Graduate School for Cellular and Biomedical Sciences, University of Bern, CH-3012 Bern, Switzerland
| | - Eva Hedlund
- Department of Neuroscience, Karolinska Institutet,171 77 Stockholm, Sweden
| | - Marc-David Ruepp
- Department of Chemistry and Biochemistry, University of Bern, CH-3012 Bern, Switzerland
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58
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Abbott M, Jain M, Pferdehirt R, Chen Y, Tran A, Duz MB, Seven M, Gibbs RA, Muzny D, Lee B, Marom R, Burrage LC. Neonatal fractures as a presenting feature of LMOD3-associated congenital myopathy. Am J Med Genet A 2017; 173:2789-2794. [PMID: 28815944 DOI: 10.1002/ajmg.a.38383] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Revised: 06/14/2017] [Accepted: 07/08/2017] [Indexed: 01/06/2023]
Abstract
Nemaline myopathy is a rare inherited disorder characterized by weakness, hypotonia, and depressed deep tendon reflexes. It is clinically and genetically heterogeneous, with the most severe phenotype presenting as perinatal akinesia, severe muscle weakness, feeding difficulties and respiratory failure, leading to early mortality. Pathogenic variants in 12 genes, encoding components of the sarcomere or factors related to myogenesis, have been reported in patients affected with the disorder. Here, we describe an early, lethal presentation of decreased fetal movements, hypotonia, muscle weakness, and neonatal respiratory failure requiring ventilator support in three siblings from a consanguineous family. All exhibited perinatal fractures, and thus, a skeletal dysplasia was considered as possibly contributing to the phenotype. However, whole exome sequencing revealed a homozygous, loss-of-function pathogenic variant in LMOD3, which has recently been associated with nemaline myopathy and, in a subset of patients, perinatal fractures. This case demonstrates the importance of considering congenital neuromuscular disorders in the differential diagnosis of perinatal fractures.
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Affiliation(s)
- Megan Abbott
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas
| | - Mahim Jain
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas
| | - Rachel Pferdehirt
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas
| | - Yuqing Chen
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas
| | - Alyssa Tran
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas
| | - Mehmet B Duz
- Department of Medical Genetics, Cerrahpasa Medical School, Istanbul University, Istanbul, Turkey
| | - Mehmet Seven
- Department of Medical Genetics, Cerrahpasa Medical School, Istanbul University, Istanbul, Turkey
| | - Richard A Gibbs
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas
| | - Donna Muzny
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas
| | - Brendan Lee
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas
| | - Ronit Marom
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas
| | - Lindsay C Burrage
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas
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59
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Schartner V, Romero NB, Donkervoort S, Treves S, Munot P, Pierson TM, Dabaj I, Malfatti E, Zaharieva IT, Zorzato F, Abath Neto O, Brochier G, Lornage X, Eymard B, Taratuto AL, Böhm J, Gonorazky H, Ramos-Platt L, Feng L, Phadke R, Bharucha-Goebel DX, Sumner CJ, Bui MT, Lacene E, Beuvin M, Labasse C, Dondaine N, Schneider R, Thompson J, Boland A, Deleuze JF, Matthews E, Pakleza AN, Sewry CA, Biancalana V, Quijano-Roy S, Muntoni F, Fardeau M, Bönnemann CG, Laporte J. Dihydropyridine receptor (DHPR, CACNA1S) congenital myopathy. Acta Neuropathol 2017; 133:517-533. [PMID: 28012042 DOI: 10.1007/s00401-016-1656-8] [Citation(s) in RCA: 74] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2016] [Revised: 12/09/2016] [Accepted: 12/11/2016] [Indexed: 10/20/2022]
Abstract
Muscle contraction upon nerve stimulation relies on excitation-contraction coupling (ECC) to promote the rapid and generalized release of calcium within myofibers. In skeletal muscle, ECC is performed by the direct coupling of a voltage-gated L-type Ca2+ channel (dihydropyridine receptor; DHPR) located on the T-tubule with a Ca2+ release channel (ryanodine receptor; RYR1) on the sarcoplasmic reticulum (SR) component of the triad. Here, we characterize a novel class of congenital myopathy at the morphological, molecular, and functional levels. We describe a cohort of 11 patients from 7 families presenting with perinatal hypotonia, severe axial and generalized weakness. Ophthalmoplegia is present in four patients. The analysis of muscle biopsies demonstrated a characteristic intermyofibrillar network due to SR dilatation, internal nuclei, and areas of myofibrillar disorganization in some samples. Exome sequencing revealed ten recessive or dominant mutations in CACNA1S (Cav1.1), the pore-forming subunit of DHPR in skeletal muscle. Both recessive and dominant mutations correlated with a consistent phenotype, a decrease in protein level, and with a major impairment of Ca2+ release induced by depolarization in cultured myotubes. While dominant CACNA1S mutations were previously linked to malignant hyperthermia susceptibility or hypokalemic periodic paralysis, our findings strengthen the importance of DHPR for perinatal muscle function in human. These data also highlight CACNA1S and ECC as therapeutic targets for the development of treatments that may be facilitated by the previous knowledge accumulated on DHPR.
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60
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Abstract
After the advances created by the use of cryostat sections and histochemistry 60 years ago, muscle histopathology is now living a real renaissance. In the field of genetic neuromuscular disorders, muscle biopsy analysis is fundamental to address questions about pathogenicity and protein expression when new genes are discovered through next-generation sequencing approaches. Moreover, the identification of the same gene mutated in previously considered distinct histopathologic entities imposes a constant reassessment of morphologic boundaries in several groups of disorders. In other fields like the acquired inflammatory myopathies, histologic analysis nowadays helps to affirm a diagnosis, set up therapeutic strategies, and verify the success of immunosuppressive treatment. In this exciting scenario morphologists are definitely key figures in the neuromuscular field. The objective of this chapter is to give an overview on morphology of the most frequent and recently identified muscle conditions, stressing the importance that only a combined analysis of clinical findings, muscle histology, and specific ancillary investigations is effective in reaching a precise diagnosis and orienting therapy.
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Affiliation(s)
- Edoardo Malfatti
- Neuromuscular Morphology Unit and Neuromuscular Pathology Reference Center Paris-Est, Center for Research in Myology, Groupe Hospitalier Universitaire La Pitié-Salpêtrière, Paris, France.
| | - Norma Beatriz Romero
- Neuromuscular Morphology Unit and Neuromuscular Pathology Reference Center Paris-Est, Center for Research in Myology, Groupe Hospitalier Universitaire La Pitié-Salpêtrière, Paris, France
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A Zebrafish Model for a Human Myopathy Associated with Mutation of the Unconventional Myosin MYO18B. Genetics 2016; 205:725-735. [PMID: 27879346 DOI: 10.1534/genetics.116.192864] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Accepted: 11/18/2016] [Indexed: 02/04/2023] Open
Abstract
Myosin 18B is an unconventional myosin that has been implicated in tumor progression in humans. In addition, loss-of-function mutations of the MYO18B gene have recently been identified in several patients exhibiting symptoms of nemaline myopathy. In mouse, mutation of Myo18B results in early developmental arrest associated with cardiomyopathy, precluding analysis of its effects on skeletal muscle development. The zebrafish, frozen (fro) mutant was identified as one of a group of immotile mutants in the 1996 Tübingen genetic screen. Mutant embryos display a loss of birefringency in their skeletal muscle, indicative of disrupted sarcomeric organization. Using meiotic mapping, we localized the fro locus to the previously unannotated zebrafish myo18b gene, the product of which shares close to 50% identity with its human ortholog. Transcription of myo18b is restricted to fast-twitch myocytes in the zebrafish embryo; consistent with this, fro mutant embryos exhibit defects specifically in their fast-twitch skeletal muscles. We show that sarcomeric assembly is blocked at an early stage in fro mutants, leading to the disorganized accumulation of actin, myosin, and α-actinin and a complete loss of myofibrillar organization in fast-twitch muscles.
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Muscle weakness in respiratory and peripheral skeletal muscles in a mouse model for nebulin-based nemaline myopathy. Neuromuscul Disord 2016; 27:83-89. [PMID: 27890461 DOI: 10.1016/j.nmd.2016.10.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2016] [Revised: 09/21/2016] [Accepted: 10/11/2016] [Indexed: 12/28/2022]
Abstract
Nemaline myopathy is among the most common non-dystrophic congenital myopathies, and is characterized by the presence of nemaline rods in skeletal muscles fibers, general muscle weakness, and hypotonia. Although respiratory failure is the main cause of death in nemaline myopathy, only little is known regarding the contractile strength of the diaphragm, the main muscle of inspiration. To investigate diaphragm contractility, in the present study we took advantage of a mouse model for nebulin-based nemaline myopathy that we recently developed. In this mouse model, exon 55 of Neb is deleted (NebΔExon55), a mutation frequently found in patients. Diaphragm contractility was determined in permeabilized muscle fibers and was compared to the contractility of permeabilized fibers from three peripheral skeletal muscles: soleus, extensor digitorum longus, and gastrocnemius. The force generating capacity of diaphragm muscle fibers of NebΔExon55 mice was reduced to 25% of wildtype levels, indicating severe contractile weakness. The contractile weakness of diaphragm fibers was more pronounced than that observed in soleus muscle, but not more pronounced than that observed in extensor digitorum longus and gastrocnemius muscles. The reduced muscle contractility was at least partly caused by changes in cross-bridge cycling kinetics which reduced the number of bound cross-bridges. The severe diaphragm weakness likely contributes to the development of respiratory failure in NebΔExon55 mice and might explain their early, postnatal death.
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Ravenscroft G, Davis MR, Lamont P, Forrest A, Laing NG. New era in genetics of early-onset muscle disease: Breakthroughs and challenges. Semin Cell Dev Biol 2016; 64:160-170. [PMID: 27519468 DOI: 10.1016/j.semcdb.2016.08.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Revised: 08/07/2016] [Accepted: 08/08/2016] [Indexed: 10/21/2022]
Abstract
Early-onset muscle disease includes three major entities that present generally at or before birth: congenital myopathies, congenital muscular dystrophies and congenital myasthenic syndromes. Almost exclusively there is weakness and hypotonia, although cases manifesting hypertonia are increasingly being recognised. These diseases display a wide phenotypic and genetic heterogeneity, with the uptake of next generation sequencing resulting in an unparalleled extension of the phenotype-genotype correlations and "diagnosis by sequencing" due to unbiased sequencing. Perhaps now more than ever, detailed clinical evaluations are necessary to guide the genetic diagnosis; with arrival at a molecular diagnosis frequently occurring following dialogue between the molecular geneticist, the referring clinician and the pathologist. There is an ever-increasing blurring of the boundaries between the congenital myopathies, dystrophies and myasthenic syndromes. In addition, many novel disease genes have been described and new insights have been gained into skeletal muscle development and function. Despite the advances made, a significant percentage of patients remain without a molecular diagnosis, suggesting that there are many more human disease genes and mechanisms to identify. It is now technically- and clinically-feasible to perform next generation sequencing for severe diseases on a population-wide scale, such that preconception-carrier screening can occur. Newborn screening for selected early-onset muscle diseases is also technically and ethically-achievable, with benefits to the patient and family from early management of these diseases and should also be implemented. The need for world-wide Reference Centres to meticulously curate polymorphisms and mutations within a particular gene is becoming increasingly apparent, particularly for interpretation of variants in the large genes which cause early-onset myopathies: NEB, RYR1 and TTN. Functional validation of candidate disease variants is crucial for accurate interpretation of next generation sequencing and appropriate genetic counseling. Many published "pathogenic" variants are too frequent in control populations and are thus likely rare polymorphisms. Mechanisms need to be put in place to systematically update the classification of variants such that accurate interpretation of variants occurs. In this review, we highlight the recent advances made and the challenges ahead for the molecular diagnosis of early-onset muscle diseases.
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Affiliation(s)
- Gianina Ravenscroft
- Harry Perkins Institute of Medical Research and the Centre for Medical Research, University of Western Australia, Nedlands, Australia
| | - Mark R Davis
- Department of Diagnostic Genomics, Pathwest, QEII Medical Centre, Nedlands, Australia
| | - Phillipa Lamont
- Harry Perkins Institute of Medical Research and the Centre for Medical Research, University of Western Australia, Nedlands, Australia; Neurogenetic unit, Dept of Neurology, Royal Perth Hospital and The Perth Children's Hospital, Western Australia, Australia
| | - Alistair Forrest
- Harry Perkins Institute of Medical Research and the Centre for Medical Research, University of Western Australia, Nedlands, Australia
| | - Nigel G Laing
- Harry Perkins Institute of Medical Research and the Centre for Medical Research, University of Western Australia, Nedlands, Australia; Department of Diagnostic Genomics, Pathwest, QEII Medical Centre, Nedlands, Australia.
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