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Karimi E, Gohlke J, van der Borgh M, Lindqvist J, Hourani Z, Kolb J, Cossette S, Lawlor MW, Ottenheijm C, Granzier H. Characterization of NEB pathogenic variants in patients reveals novel nemaline myopathy disease mechanisms and omecamtiv mecarbil force effects. Acta Neuropathol 2024; 147:72. [PMID: 38634969 PMCID: PMC11026289 DOI: 10.1007/s00401-024-02726-w] [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: 12/22/2023] [Revised: 03/19/2024] [Accepted: 03/26/2024] [Indexed: 04/19/2024]
Abstract
Nebulin, a critical protein of the skeletal muscle thin filament, plays important roles in physiological processes such as regulating thin filament length (TFL), cross-bridge cycling, and myofibril alignment. Pathogenic variants in the nebulin gene (NEB) cause NEB-based nemaline myopathy (NEM2), a genetically heterogeneous disorder characterized by hypotonia and muscle weakness, currently lacking curative therapies. In this study, we examined a cohort of ten NEM2 patients, each with unique pathogenic variants, aiming to understand their impact on mRNA, protein, and functional levels. Results show that pathogenic truncation variants affect NEB mRNA stability and lead to nonsense-mediated decay of the mutated transcript. Moreover, a high incidence of cryptic splice site activation was found in patients with pathogenic splicing variants that are expected to disrupt the actin-binding sites of nebulin. Determination of protein levels revealed patients with either relatively normal or markedly reduced nebulin. We observed a positive relation between the reduction in nebulin and a reduction in TFL, or reduction in tension (both maximal and submaximal tension). Interestingly, our study revealed a pathogenic duplication variant in nebulin that resulted in a four-copy gain in the triplicate region of NEB and a much larger nebulin protein and longer TFL. Additionally, we investigated the effect of Omecamtiv mecarbil (OM), a small-molecule activator of cardiac myosin, on force production of type 1 muscle fibers of NEM2 patients. OM treatment substantially increased submaximal tension across all NEM2 patients ranging from 87 to 318%, with the largest effects in patients with the lowest level of nebulin. In summary, this study indicates that post-transcriptional or post-translational mechanisms regulate nebulin expression. Moreover, we propose that the pathomechanism of NEM2 involves not only shortened but also elongated thin filaments, along with the disruption of actin-binding sites resulting from pathogenic splicing variants. Significantly, our findings highlight the potential of OM treatment to improve skeletal muscle function in NEM2 patients, especially those with large reductions in nebulin levels.
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Affiliation(s)
- Esmat Karimi
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ, USA
| | - Jochen Gohlke
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ, USA
| | - Mila van der Borgh
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ, USA
| | - Johan Lindqvist
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ, USA
| | - Zaynab Hourani
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ, USA
| | - Justin Kolb
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ, USA
| | - Stacy Cossette
- Department of Pathology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Michael W Lawlor
- Department of Pathology, Medical College of Wisconsin, Milwaukee, WI, USA
- Diverge Translational Science Laboratory, Milwaukee, WI, USA
| | - Coen Ottenheijm
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ, USA
- Department of Physiology, Amsterdam UMC (Location VUMC), Amsterdam, Netherlands
| | - Henk Granzier
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ, USA.
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2
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Buchignani B, Marinella G, Pasquariello R, Sgherri G, Frosini S, Santorelli FM, Orsini A, Battini R, Astrea G. KLHL40-Related Myopathy: A Systematic Review and Insight into a Follow-up Biomarker via a New Case Report. Genes (Basel) 2024; 15:208. [PMID: 38397198 PMCID: PMC10887776 DOI: 10.3390/genes15020208] [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: 01/15/2024] [Revised: 01/30/2024] [Accepted: 01/31/2024] [Indexed: 02/25/2024] Open
Abstract
BACKGROUND Mutations in the KLHL40 gene are a common cause of severe or even lethal nemaline myopathy. Some cases with mild forms have been described, although the cases are still anecdotal. The aim of this paper was to systematically review the cases described in the literature and to describe a 12-year clinical and imaging follow-up in an Italian patient with KLHL40- related myopathy in order to suggest possible follow-up measurements. METHODS Having searched through three electronic databases (PubMed, Scopus, and EBSCO), 18 articles describing 65 patients with homozygous or compound heterozygous KLHL40 mutations were selected. A patient with a KLHL40 homozygous mutation (c.1582G>A/p.E528K) was added and clinical and genetic data were collected. RESULTS The most common mutation identified in our systematic review was the (c.1516A>C) followed by the (c.1582G>A). In our review, 60% percent of the patients died within the first 4 years of life. Clinical features were similar across the sample. Unfortunately, however, there is no record of the natural history data in the surviving patients. The 12-year follow-up of our patient revealed a slow improvement in her clinical course, identifying muscle MRI as the only possible marker of disease progression. CONCLUSIONS Due to its clinical and genotype homogeneity, KLHL40-related myopathy may be a condition that would greatly benefit from the development of new gene therapies; muscle MRI could be a good biomarker to monitor disease progression.
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Affiliation(s)
- Bianca Buchignani
- Department of Neuroscience, IRCCS Stella Maris Foundation, 56128 Pisa, Italy; (B.B.); (G.M.); (R.P.); (G.S.); (S.F.); (G.A.)
- Department of Translational Research and of New Surgical and Medical Technologies, University of Pisa, 56126 Pisa, Italy
| | - Gemma Marinella
- Department of Neuroscience, IRCCS Stella Maris Foundation, 56128 Pisa, Italy; (B.B.); (G.M.); (R.P.); (G.S.); (S.F.); (G.A.)
| | - Rosa Pasquariello
- Department of Neuroscience, IRCCS Stella Maris Foundation, 56128 Pisa, Italy; (B.B.); (G.M.); (R.P.); (G.S.); (S.F.); (G.A.)
| | - Giada Sgherri
- Department of Neuroscience, IRCCS Stella Maris Foundation, 56128 Pisa, Italy; (B.B.); (G.M.); (R.P.); (G.S.); (S.F.); (G.A.)
| | - Silvia Frosini
- Department of Neuroscience, IRCCS Stella Maris Foundation, 56128 Pisa, Italy; (B.B.); (G.M.); (R.P.); (G.S.); (S.F.); (G.A.)
| | | | - Alessandro Orsini
- Pediatric Neurology, Azienda Ospedaliera Universitaria Pisana, 56100 Pisa, Italy;
| | - Roberta Battini
- Department of Neuroscience, IRCCS Stella Maris Foundation, 56128 Pisa, Italy; (B.B.); (G.M.); (R.P.); (G.S.); (S.F.); (G.A.)
- Department of Clinical and Experimental Medicine, University of Pisa, 56126 Pisa, Italy
| | - Guja Astrea
- Department of Neuroscience, IRCCS Stella Maris Foundation, 56128 Pisa, Italy; (B.B.); (G.M.); (R.P.); (G.S.); (S.F.); (G.A.)
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3
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Karimi E, van der Borgh M, Lindqvist J, Gohlke J, Hourani Z, Kolb J, Cossette S, Lawlor MW, Ottenheijm C, Granzier H. Characterization of NEB mutations in patients reveals novel nemaline myopathy disease mechanisms and omecamtiv mecarbil force effects. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.20.572678. [PMID: 38187705 PMCID: PMC10769406 DOI: 10.1101/2023.12.20.572678] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2024]
Abstract
Nebulin, a critical protein of the skeletal muscle thin filament, plays important roles in physiological processes such as regulating thin filament length (TFL), cross-bridge cycling, and myofibril alignment. Mutations in the nebulin gene ( NEB ) cause NEB-based nemaline myopathy (NEM2), a genetically heterogeneous disorder characterized by hypotonia and muscle weakness, currently lacking therapies targeting the underlying pathological mechanisms. In this study, we examined a cohort of ten NEM2 patients, each with unique mutations, aiming to understand their impact on mRNA, protein, and functional levels. Results show that truncation mutations affect NEB mRNA stability and lead to nonsense-mediated decay of the mutated transcript. Moreover, a high incidence of cryptic splice site activation was found in patients with splicing mutations which is expected to disrupt the actin-binding sites of nebulin. Determination of protein levels revealed patients with relatively normal nebulin levels and others with markedly reduced nebulin. We observed a positive relation between the reduction in nebulin and a reduction in TFL, and a positive relation between the reduction in nebulin level and the reduction in tension (both maximal and submaximal tension). Interestingly, our study revealed a duplication mutation in nebulin that resulted in a larger nebulin protein and longer TFL. Additionally, we investigated the effect of Omecamtiv mecarbil (OM), a small-molecule activator of cardiac myosin, on force production of type I muscle fibers of NEM2 patients. OM treatment substantially increased submaximal tension across all NEM2 patients ranging from 87-318%, with the largest effects in patients with the lowest level of nebulin. In summary, this study indicates that post-transcriptional or post-translational mechanisms regulate nebulin expression. Moreover, we propose that the pathomechanism of NEM2 involves not only shortened but also elongated thin filaments, along with the disruption of actin-binding sites resulting from splicing mutations. Significantly, our findings highlight the potential of OM treatment to improve skeletal muscle function in NEM2 patients, especially those with large reductions in nebulin levels.
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4
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Laitila J, Wallgren-Pettersson C. Recent advances in nemaline myopathy. Neuromuscul Disord 2021; 31:955-967. [PMID: 34561123 DOI: 10.1016/j.nmd.2021.07.012] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2021] [Revised: 07/14/2021] [Accepted: 07/16/2021] [Indexed: 11/18/2022]
Abstract
The nemaline myopathies constitute a large proportion of the congenital or structural myopathies. Common to all patients is muscle weakness and the presence in the muscle biopsy of nemaline rods. The causative genes are at least twelve, encoding structural or regulatory proteins of the thin filament, and the clinical picture as well as the histological appearance on muscle biopsy vary widely. Here, we suggest a renewed clinical classification to replace the original one, summarise what is known about the pathogenesis from mutations in each causative gene to the forms of nemaline myopathy described to date, and provide perspectives on pathogenetic mechanisms possibly open to therapeutic modalities.
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Affiliation(s)
- Jenni Laitila
- The Folkhälsan Institute of Genetics, Folkhälsan Research Center, Helsinki, Finland; Department of Medical Genetics, Medicum, University of Helsinki, Finland; Department of Biomedical Sciences, University of Copenhagen, Denmark.
| | - Carina Wallgren-Pettersson
- The Folkhälsan Institute of Genetics, Folkhälsan Research Center, Helsinki, Finland; Department of Medical Genetics, Medicum, University of Helsinki, Finland
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5
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Laflamme N, Lace B, Thonta Setty S, Rioux N, Labrie Y, Droit A, Chrestian N, Rivest S. A Homozygous Deep Intronic Mutation Alters the Splicing of Nebulin Gene in a Patient With Nemaline Myopathy. Front Neurol 2021; 12:660113. [PMID: 34211429 PMCID: PMC8239344 DOI: 10.3389/fneur.2021.660113] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Accepted: 05/11/2021] [Indexed: 11/19/2022] Open
Abstract
Nemaline myopathy is a rare disorder affecting the muscle sarcomere. Mutations in nebulin gene (NEB) are known to be responsible for about 50% of nemaline myopathy cases. Nebulin is a giant protein which is formed integrally with the sarcomeric thin filament. This complex gene is under extensive alternative splicing giving rise to multiple isoforms. In this study, we report a 6-year-old boy presenting with general muscular weaknesses. Identification of rod-shaped structures in the patient' biopsy raised doubt about the presence of a nemaline myopathy. Next-generation sequencing was used to identify a causative mutation for the patient syndrome. A homozygous deep intronic substitution was found in the intron 144 of the NEB. The variant was predicted by in silico tools to create a new donor splice site. Molecular analysis has shown that the mutation could alter splicing events of the nebulin gene leading to a significant decrease of isoforms level. This change in the expression level of nebulin could give rise to functional consequences in the sarcomere. These results are consistent with the phenotypes observed in the patient. Such a discovery of variants in this gene will allow a better understanding of the involvement of nebulin in neuromuscular diseases and help find new treatments for the nemaline myopathy.
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Affiliation(s)
- Nathalie Laflamme
- Centre de recherche CHU de Québec- Laval University, Quebec City, QC, Canada
| | - Baiba Lace
- Department of Medical Genetics, Centre Mère Enfant Soleil, Laval University, Quebec City, QC, Canada
| | | | - Nadie Rioux
- Centre de recherche CHU de Québec- Laval University, Quebec City, QC, Canada
| | - Yvan Labrie
- Centre de recherche CHU de Québec- Laval University, Quebec City, QC, Canada
| | - Arnaud Droit
- Centre de recherche CHU de Québec- Laval University, Quebec City, QC, Canada
| | - Nicolas Chrestian
- Department of Pediatric Neurology, Pediatric Neuromuscular Disorder, Centre Mère Enfant Soleil, Laval University, Quebec City, QC, Canada
| | - Serge Rivest
- Centre de recherche CHU de Québec- Laval University, Quebec City, QC, Canada
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6
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Gohlke J, Tonino P, Lindqvist J, Smith JE, Granzier H. The number of Z-repeats and super-repeats in nebulin greatly varies across vertebrates and scales with animal size. J Gen Physiol 2020; 153:211611. [PMID: 33337482 PMCID: PMC7754682 DOI: 10.1085/jgp.202012783] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 11/20/2020] [Indexed: 12/18/2022] Open
Abstract
Nebulin is a skeletal muscle protein that associates with the sarcomeric thin filaments and has functions in regulating the length of the thin filament and the structure of the Z-disk. Here we investigated the nebulin gene in 53 species of birds, fish, amphibians, reptiles, and mammals. In all species, nebulin has a similar domain composition that mostly consists of ∼30-residue modules (or simple repeats), each containing an actin-binding site. All species have a large region where simple repeats are organized into seven-module super-repeats, each containing a tropomyosin binding site. The number of super-repeats shows high interspecies variation, ranging from 21 (zebrafish, hummingbird) to 31 (camel, chimpanzee), and, importantly, scales with body size. The higher number of super-repeats in large animals was shown to increase thin filament length, which is expected to increase the sarcomere length for optimal force production, increase the energy efficiency of isometric force production, and lower the shortening velocity of muscle. It has been known since the work of A.V. Hill in 1950 that as species increase in size, the shortening velocity of their muscle is reduced, and the present work shows that nebulin contributes to the mechanistic basis. Finally, we analyzed the differentially spliced simple repeats in nebulin's C terminus, whose inclusion correlates with the width of the Z-disk. The number of Z-repeats greatly varies (from 5 to 18) and correlates with the number of super-repeats. We propose that the resulting increase in the width of the Z-disk in large animals increases the number of contacts between nebulin and structural Z-disk proteins when the Z-disk is stressed for long durations.
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Affiliation(s)
- Jochen Gohlke
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ
| | - Paola Tonino
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ
| | - Johan Lindqvist
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ
| | - John E Smith
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ
| | - Henk Granzier
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ
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7
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Triggering typical nemaline myopathy with compound heterozygous nebulin mutations reveals myofilament structural changes as pathomechanism. Nat Commun 2020; 11:2699. [PMID: 32483185 PMCID: PMC7264197 DOI: 10.1038/s41467-020-16526-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Accepted: 05/06/2020] [Indexed: 12/26/2022] Open
Abstract
Nebulin is a giant protein that winds around the actin filaments in the skeletal muscle sarcomere. Compound-heterozygous mutations in the nebulin gene (NEB) cause typical nemaline myopathy (NM), a muscle disorder characterized by muscle weakness with limited treatment options. We created a mouse model with a missense mutation p.Ser6366Ile and a deletion of NEB exon 55, the Compound-Het model that resembles typical NM. We show that Compound-Het mice are growth-retarded and have muscle weakness. Muscles have a reduced myofibrillar fractional-area and sarcomeres are disorganized, contain rod bodies, and have longer thin filaments. In contrast to nebulin-based severe NM where haplo-insufficiency is the disease driver, Compound-Het mice express normal amounts of nebulin. X-ray diffraction revealed that the actin filament is twisted with a larger radius, that tropomyosin and troponin behavior is altered, and that the myofilament spacing is increased. The unique disease mechanism of nebulin-based typical NM reveals novel therapeutic targets. Nebulin-based nemaline myopathy is a heterogenous disease with unclear pathological mechanisms. Here, the authors generate a mouse model that mimics the most common genetic cause of the disease and demonstrate that muscle weakness in this model is associated with twisted actin filaments and altered tropomyosin and troponin behaviour.
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8
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Yeung KS, Yu FNY, Fung CW, Wong S, Lee HHC, Fung STH, Fung GPG, Leung KY, Chung WH, Lee YT, Ng VKS, Yu MHC, Fung JLF, Tsang MHY, Chan KYK, Chan SHS, Kan ASY, Chung BHY. The KLHL40 c.1516A>C is a Chinese-specific founder mutation causing nemaline myopathy 8: Report of six patients with pre- and postnatal phenotypes. Mol Genet Genomic Med 2020; 8:e1229. [PMID: 32352246 PMCID: PMC7336759 DOI: 10.1002/mgg3.1229] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2020] [Revised: 03/09/2020] [Accepted: 03/12/2020] [Indexed: 12/29/2022] Open
Abstract
Background Autosomal recessive or compound heterozygous mutations in KLHL40 cause nemaline myopathy 8, which is one of the most severe forms of nemaline myopathy. The KLHL40 c.1516A>C variant has recently been reported as a founder mutation in southern Chinese. Methods We report six cases of nemaline myopathy 8 which involves the c.1516A>C variant, from five unrelated families of non‐consanguineous southern Chinese. The pre‐ and postnatal phenotypes of these cases were reviewed with emphasis on prenatal clinical features. Genetic testing for the founder mutation was performed on three patients with homozygous mutations. Results Common prenatal features included reduced fetal movement, polyhydramnios, breech presentation, and clubfeet. Two pregnancies were terminated. Four live‐born patients had postnatal features typical of nemaline myopathy 8. The length of survival ranged from 49 days to 17 months, with respiratory failure and infections being the principal causes of death. Haplotype analysis in three patients with homozygous mutation showed a shared haplotype block of 1.1727 cM spanning over the c.1516A>C variant, suggesting it is a southern Chinese‐specific founder mutation. Conclusion Analysis of the KLHL40 c.1516A>C variant should be considered in prenatal diagnosis of Chinese pregnant patients with suspected congenital neuromuscular disorders or with significant family history of congenital myopathies.
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Affiliation(s)
- Kit San Yeung
- Department of Paediatrics and Adolescent Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, Hong Kong, China
| | - Florrie N Y Yu
- Department of Obstetrics and Gynaecology, Queen Elizabeth Hospital, Hong Kong Special Administrative Region, Hong Kong, China
| | - Cheuk Wing Fung
- Department of Paediatrics and Adolescent Medicine, Hong Kong Children's Hospital, Hong Kong Special Administrative Region, Hong Kong, China
| | - Sheila Wong
- Department of Paediatrics and Adolescent Medicine, Hong Kong Children's Hospital, Hong Kong Special Administrative Region, Hong Kong, China
| | - Hencher H C Lee
- Department of Pathology, Princess Margaret Hospital, Hong Kong Special Administrative Region, Hong Kong, China
| | - Sharon T H Fung
- Department of Paediatrics, Kwong Wah Hospital, Hong Kong Special Administrative Region, Hong Kong, China
| | - Genevieve P G Fung
- Department of Paediatrics and Adolescent Medicine, United Christian Hospital, Hong Kong Special Administrative Region, Hong Kong, China
| | - Kwok Yin Leung
- Department of Obstetrics and Gynaecology, Queen Elizabeth Hospital, Hong Kong Special Administrative Region, Hong Kong, China
| | - Wai Hang Chung
- Department of Obstetrics and Gynaecology, United Christian Hospital, Hong Kong Special Administrative Region, Hong Kong, China
| | - Yun Ting Lee
- Department of Obstetrics and Gynaecology, Princess Margaret Hospital, Hong Kong Special Administrative Region, Hong Kong, China
| | - Vivian K S Ng
- Department of Obstetrics and Gyanecology, Kwong Wah Hospital, Hong Kong Special Administrative Region, Hong Kong, China
| | - Mullin H C Yu
- Department of Paediatrics and Adolescent Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, Hong Kong, China
| | - Jasmine L F Fung
- Department of Paediatrics and Adolescent Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, Hong Kong, China
| | - Mandy H Y Tsang
- Department of Paediatrics and Adolescent Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, Hong Kong, China
| | - Kelvin Y K Chan
- Prenatal Diagnostic Laboratory, Department of Obstetrics and Gynaecology, Tsan Yuk Hospital, Hong Kong Special Administrative Region, Hong Kong, China.,Department of Obstetrics and Gynaecology, Queen Mary Hospital, Hong Kong Special Administrative Region, Hong Kong, China
| | - Sophelia H S Chan
- Department of Paediatrics and Adolescent Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, Hong Kong, China
| | - Anita S Y Kan
- Prenatal Diagnostic Laboratory, Department of Obstetrics and Gynaecology, Tsan Yuk Hospital, Hong Kong Special Administrative Region, Hong Kong, China.,Department of Obstetrics and Gynaecology, Queen Mary Hospital, Hong Kong Special Administrative Region, Hong Kong, China
| | - Brian H Y Chung
- Department of Paediatrics and Adolescent Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, Hong Kong, China
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9
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Abstract
Nebulin, encoded by NEB, is a giant skeletal muscle protein of about 6669 amino acids which forms an integral part of the sarcomeric thin filament. In recent years, the nebula around this protein has been largely lifted resulting in the discovery that nebulin is critical for a number of tasks in skeletal muscle. In this review, we firstly discussed nebulin’s role as a structural component of the thin filament and the Z-disk, regulating the length and the mechanical properties of the thin filament as well as providing stability to myofibrils by interacting with structural proteins within the Z-disk. Secondly, we reviewed nebulin’s involvement in the regulation of muscle contraction, cross-bridge cycling kinetics, Ca2+-homeostasis and excitation contraction (EC) coupling. While its role in Ca2+-homeostasis and EC coupling is still poorly understood, a large number of studies have helped to improve our knowledge on how nebulin affects skeletal muscle contractile mechanics. These studies suggest that nebulin affects the number of force generating actin-myosin cross-bridges and may also affect the force that each cross-bridge produces. It may exert this effect by interacting directly with actin and myosin and/or indirectly by potentially changing the localisation and function of the regulatory complex (troponin and tropomyosin). Besides unravelling the biology of nebulin, these studies are particularly helpful in understanding the patho-mechanism of myopathies caused by NEB mutations, providing knowledge which constitutes the critical first step towards the development of therapeutic interventions. Currently, effective treatments are not available, although a number of therapeutic strategies are being investigated.
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10
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Abstract
Nemaline myopathy (NM) is among the most common non-dystrophic congenital myopathies (incidence 1:50.000). Hallmark features of NM are skeletal muscle weakness and the presence of nemaline bodies in the muscle fiber. The clinical phenotype of NM patients is quite diverse, ranging from neonatal death to normal lifespan with almost normal motor function. As the respiratory muscles are involved as well, severely affected patients are ventilator-dependent. The mechanisms underlying muscle weakness in NM are currently poorly understood. Therefore, no therapeutic treatment is available yet. Eleven implicated genes have been identified: ten genes encode proteins that are either components of thin filament, or are thought to contribute to stability or turnover of thin filament proteins. The thin filament is a major constituent of the sarcomere, the smallest contractile unit in muscle. It is at this level of contraction – thin-thick filament interaction – where muscle weakness originates in NM patients. This review focusses on how sarcomeric gene mutations directly compromise sarcomere function in NM. Insight into the contribution of sarcomeric dysfunction to muscle weakness in NM, across the genes involved, will direct towards the development of targeted therapeutic strategies.
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Affiliation(s)
| | - Coen A.C. Ottenheijm
- Correspondence to: Coen Ottenheijm, PhD, Department of Physiology, VU University Medical Center, O|2 building, 12W-51, De Boelelaan 1118, 1081 HV Amsterdam, The Netherlands. Tel.: +31 20 4448123; Fax: +31 20 4448124; E-mail:
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11
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Sewry CA, Laitila JM, Wallgren-Pettersson C. Nemaline myopathies: a current view. J Muscle Res Cell Motil 2019; 40:111-126. [PMID: 31228046 PMCID: PMC6726674 DOI: 10.1007/s10974-019-09519-9] [Citation(s) in RCA: 110] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Accepted: 05/29/2019] [Indexed: 12/13/2022]
Abstract
Nemaline myopathies are a heterogenous group of congenital myopathies caused by de novo, dominantly or recessively inherited mutations in at least twelve genes. The genes encoding skeletal α-actin (ACTA1) and nebulin (NEB) are the commonest genetic cause. Most patients have congenital onset characterized by muscle weakness and hypotonia, but the spectrum of clinical phenotypes is broad, ranging from severe neonatal presentations to onset of a milder disorder in childhood. Most patients with adult onset have an autoimmune-related myopathy with a progressive course. The wide application of massively parallel sequencing methods is increasing the number of known causative genes and broadening the range of clinical phenotypes. Nemaline myopathies are identified by the presence of structures that are rod-like or ovoid in shape with electron microscopy, and with light microscopy stain red with the modified Gömöri trichrome technique. These rods or nemaline bodies are derived from Z lines (also known as Z discs or Z disks) and have a similar lattice structure and protein content. Their shape in patients with mutations in KLHL40 and LMOD3 is distinctive and can be useful for diagnosis. The number and distribution of nemaline bodies varies between fibres and different muscles but does not correlate with severity or prognosis. Additional pathological features such as caps, cores and fibre type disproportion are associated with the same genes as those known to cause the presence of rods. Animal models are advancing the understanding of the effects of various mutations in different genes and paving the way for the development of therapies, which at present only manage symptoms and are aimed at maintaining muscle strength, joint mobility, ambulation, respiration and independence in the activities of daily living.
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Affiliation(s)
- Caroline A Sewry
- Dubowitz Neuromuscular Centre, UCL Institute of Child Health and Great Ormond Street Hospital, 30 Guilford Street, London, WC1N 1EH, UK. .,Wolfson Centre of Inherited Neuromuscular Disorders, RJAH Orthopaedic Hospital, Oswestry, SY10 7AG, UK.
| | - Jenni M Laitila
- Folkhälsan Institute of Genetics, Folkhälsan Research Center, Helsinki, Finland.,Department of Medical and Clinical Genetics, Medicum, University of Helsinki, Helsinki, Finland
| | - Carina Wallgren-Pettersson
- Folkhälsan Institute of Genetics, Folkhälsan Research Center, Helsinki, Finland.,Department of Medical and Clinical Genetics, Medicum, University of Helsinki, Helsinki, Finland
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12
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Moreau-Le Lan S, Aller E, Calabria I, Gonzalez-Tarancon L, Cardona-Gay C, Martinez-Matilla M, Aparisi MJ, Selles J, Sagath L, Pitarch I, Muelas N, Cervera JV, Millan JM, Pedrola L. New mutations found by Next-Generation Sequencing screening of Spanish patients with Nemaline Myopathy. PLoS One 2018; 13:e0207296. [PMID: 30517146 PMCID: PMC6281284 DOI: 10.1371/journal.pone.0207296] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Accepted: 10/29/2018] [Indexed: 02/03/2023] Open
Abstract
Nemaline Myopathy (NM) is a rare genetic disorder that encompasses a large spectrum of myopathies characterized by hypotonia and generalized muscle weakness. To date, mutations in thirteen different genes have been associated with NM. The most frequently responsible genes are NEB (50% of cases) and ACTA1 (15–25% of cases). In this report all known NM related genes were screened by Next Generation Sequencing in five Spanish patients in order to genetically confirm the clinical and histological diagnosis of NM. Four mutations in NEB (c.17779_17780delTA, c.11086A>C, c.21076C>T and c.2310+5G>A) and one mutation in ACTA1 (c.871A>T) were found in four patients. Three of the four mutations in NEB were novel. A cDNA sequencing assay of the novel variants c.17779_17780delTA, c.11086A>C and c.2310+5G>A revealed that the intronic variant c.2310+5G>A affected the splicing process. Mutations reported here could help clinicians and geneticists in NM diagnosis.
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Affiliation(s)
- Sarah Moreau-Le Lan
- Genomic Unit, Health Research Institute Hospital La Fe (IIS La Fe), Valencia, Spain
| | - Elena Aller
- Genetics Unit, La Fe University Hospital, Valencia, Spain
- Research Group on Molecular, Cellular and Genomic Biomedicine, Instituto de Investigación Sanitaria La Fe, Valencia, Spain
- Biomedical Network Research Center for Rare Diseases (CIBERER), Madrid, Spain
| | - Ines Calabria
- Genomic Unit, Health Research Institute Hospital La Fe (IIS La Fe), Valencia, Spain
| | | | - Cristina Cardona-Gay
- Genomic Unit, Health Research Institute Hospital La Fe (IIS La Fe), Valencia, Spain
| | | | - Maria J. Aparisi
- Genomic Unit, Health Research Institute Hospital La Fe (IIS La Fe), Valencia, Spain
| | - Jorge Selles
- Genomic Unit, Health Research Institute Hospital La Fe (IIS La Fe), Valencia, Spain
| | - Lydia Sagath
- The Folkhälsan Institute of Genetics and the Department of Medical and Clinical Genetics, Medicum, University of Helsinki, Finland
| | - Inmaculada Pitarch
- Unit of Rare Neuromuscular Diseases, La Fe University Hospital, Valencia, Spain
| | - Nuria Muelas
- Biomedical Network Research Center in Oncology (CIBERONC), Madrid, Spain
- Neuromuscular Diseases Unit, Neurology Department, La Fe University Hospital, Valencia, Spain, and Neuromuscular & Ataxias Research Group, Instituto de Investigación Sanitaria La Fe, Valencia, Spain
| | - Jose V. Cervera
- Genetics Unit, La Fe University Hospital, Valencia, Spain
- Biomedical Network Research Center in Oncology (CIBERONC), Madrid, Spain
| | - Jose M. Millan
- Genomic Unit, Health Research Institute Hospital La Fe (IIS La Fe), Valencia, Spain
- Research Group on Molecular, Cellular and Genomic Biomedicine, Instituto de Investigación Sanitaria La Fe, Valencia, Spain
- Biomedical Network Research Center for Rare Diseases (CIBERER), Madrid, Spain
| | - Laia Pedrola
- Genomic Unit, Health Research Institute Hospital La Fe (IIS La Fe), Valencia, Spain
- * E-mail:
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13
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Sagath L, Lehtokari VL, Välipakka S, Udd B, Wallgren-Pettersson C, Pelin K, Kiiski K. An Extended Targeted Copy Number Variation Detection Array Including 187 Genes for the Diagnostics of Neuromuscular Disorders. J Neuromuscul Dis 2018; 5:307-314. [PMID: 30040739 PMCID: PMC6087456 DOI: 10.3233/jnd-170298] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
BACKGROUND Our previous array, the Comparative Genomic Hybridisation design (CGH-array) for nemaline myopathy (NM), named the NM-CGH array, revealed pathogenic copy number variation (CNV) in the genes for nebulin (NEB) and tropomyosin 3 (TPM3), as well as recurrent CNVs in the segmental duplication (SD), i.e. triplicate, region of NEB (TRI, exons 82-89, 90-97, 98-105). In the light of this knowledge, we have designed and validated an extended CGH array, which includes a selection of 187 genes known to cause neuromuscular disorders (NMDs). OBJECTIVE Our aim was to develop a reliable method for CNV detection in genes related to neuromuscular disorders for routine mutation detection and analysis, as a much-needed complement to sequencing methods. METHODS We have developed a novel custom-made 4×180 k CGH array for the diagnostics of NMDs. It includes the same tiled ultra-high density coverage of the 12 known or putative NM genes as our 8×60 k NM-CGH-array but also comprises a selection of 175 additional genes associated with NMDs, including titin (TTN), at a high to very high coverage. The genes were divided into three coverage groups according to known and potential pathogenicity in neuromuscular disorders. RESULTS The array detected known and putative CNVs in all three gene coverage groups, including the repetitive regions of NEB and TTN. CONCLUSIONS The targeted neuromuscular disorder 4×180 k array-CGH (NMD-CGH-array v1.0) design allows CNV detection for a broader spectrum of neuromuscular disorders at a high resolution.
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Affiliation(s)
- Lydia Sagath
- The Folkhälsan Institute of Genetics and the Department of Medical and Clinical Genetics, Medicum, University of Helsinki, Finland
| | - Vilma-Lotta Lehtokari
- The Folkhälsan Institute of Genetics and the Department of Medical and Clinical Genetics, Medicum, University of Helsinki, Finland
| | - Salla Välipakka
- The Folkhälsan Institute of Genetics and the Department of Medical and Clinical Genetics, Medicum, University of Helsinki, Finland
| | - Bjarne Udd
- The Folkhälsan Institute of Genetics and the Department of Medical and Clinical Genetics, Medicum, University of Helsinki, Finland
- Neuromuscular Research Center, Tampere University and University Hospital, Finland
- Department of Neurology, Vaasa Central Hospital, Finland
| | - Carina Wallgren-Pettersson
- The Folkhälsan Institute of Genetics and the Department of Medical and Clinical Genetics, Medicum, University of Helsinki, Finland
| | - Katarina Pelin
- The Folkhälsan Institute of Genetics and the Department of Medical and Clinical Genetics, Medicum, University of Helsinki, Finland
- Faculty of Biological and Environmental Sciences, Molecular and Integrative Biosciences Research Programme, University of Helsinki, Finland
| | - Kirsi Kiiski
- The Folkhälsan Institute of Genetics and the Department of Medical and Clinical Genetics, Medicum, University of Helsinki, Finland
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14
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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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15
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Konersman CG, Freyermuth F, Winder TL, Lawlor MW, Lagier-Tourenne C, Patel SB. Novel autosomal dominant TNNT1 mutation causing nemaline myopathy. Mol Genet Genomic Med 2017; 5:678-691. [PMID: 29178646 PMCID: PMC5702563 DOI: 10.1002/mgg3.325] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Revised: 07/13/2017] [Accepted: 07/18/2017] [Indexed: 01/30/2023] Open
Abstract
Background Nemaline myopathy (NEM) is one of the three major forms of congenital myopathy and is characterized by diffuse muscle weakness, hypotonia, respiratory insufficiency, and the presence of nemaline rod structures on muscle biopsy. Mutations in troponin T1 (TNNT1) is 1 of 10 genes known to cause NEM. To date, only homozygous nonsense mutations or compound heterozygous truncating or internal deletion mutations in TNNT1 gene have been identified in NEM. This extended family is of historical importance as some members were reported in the 1960s as initial evidence that NEM is a hereditary disorder. Methods Proband and extended family underwent Sanger sequencing for TNNT1. We performed RT‐PCR and immunoblot on muscle to assess TNNT1 RNA expression and protein levels in proband and father. Results We report a novel heterozygous missense mutation of TNNT1 c.311A>T (p.E104V) that segregated in an autosomal dominant fashion in a large family residing in the United States. Extensive sequencing of the other known genes for NEM failed to identify any other mutant alleles. Muscle biopsies revealed a characteristic pattern of nemaline rods and severe myofiber hypotrophy that was almost entirely restricted to the type 1 fiber population. Conclusion This novel mutation alters a residue that is highly conserved among vertebrates. This report highlights not only a family with autosomal dominant inheritance of NEM, but that this novel mutation likely acts via a dominant negative mechanism.
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Affiliation(s)
- Chamindra G Konersman
- Department of Neurosciences, University of California San Diego, San Diego, California
| | - Fernande Freyermuth
- MassGeneral Institute for Neurodegenerative Disease, Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts.,Broad Institute of Harvard University and MIT, Cambridge, Massachusetts
| | | | - Michael W Lawlor
- Division of Pediatric Pathology, Department of Pathology and Laboratory Medicine and Neuroscience Research Center, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Clotilde Lagier-Tourenne
- MassGeneral Institute for Neurodegenerative Disease, Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts.,Broad Institute of Harvard University and MIT, Cambridge, Massachusetts
| | - Shailendra B Patel
- Division of Endocrinology, Metabolism and Clinical Nutrition, Medical College of Wisconsin, and Clement J. Zablocki VAMC, Milwaukee, Wisconsin
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16
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Feingold-Zadok M, Chitayat D, Chong K, Injeyan M, Shannon P, Chapmann D, Maymon R, Pillar N, Reish O. Mutations in the NEB
gene cause fetal akinesia/arthrogryposis multiplex congenita. Prenat Diagn 2017; 37:144-150. [DOI: 10.1002/pd.4977] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Revised: 11/23/2016] [Accepted: 11/25/2016] [Indexed: 12/11/2022]
Affiliation(s)
- Michal Feingold-Zadok
- Genetic Institute; Assaf Harofeh Medical Center; Zerifin Israel
- Sackler School of Medicine; Tel Aviv University; Tel Aviv Israel
- Department of Obstetrics and Gynecology Ward, Ultrasound Unit; Assaf Harofeh Medical Center; Zerifin Israel
| | - David Chitayat
- Prenatal Diagnosis and Medical Genetics Program, Department of Obstetrics and gynecology, Mount Sinai Hospital; University of Toronto; Toronto Ontario Canada
| | - Karen Chong
- Prenatal Diagnosis and Medical Genetics Program, Department of Obstetrics and gynecology, Mount Sinai Hospital; University of Toronto; Toronto Ontario Canada
| | - Marie Injeyan
- Prenatal Diagnosis and Medical Genetics Program, Department of Obstetrics and gynecology, Mount Sinai Hospital; University of Toronto; Toronto Ontario Canada
| | - Patrick Shannon
- Department of Laboratory Medicine and Pathobiology, Mount Sinai Hospital; University of Toronto; Toronto Ontario Canada
| | - Daphne Chapmann
- Genetic Institute; Assaf Harofeh Medical Center; Zerifin Israel
| | - Ron Maymon
- Sackler School of Medicine; Tel Aviv University; Tel Aviv Israel
- Department of Obstetrics and Gynecology Ward, Ultrasound Unit; Assaf Harofeh Medical Center; Zerifin Israel
| | - Nir Pillar
- Bioinformatic Division, Sackler School of Medicine; Tel Aviv University; Tel Aviv Israel
| | - Orit Reish
- Genetic Institute; Assaf Harofeh Medical Center; Zerifin Israel
- Sackler School of Medicine; Tel Aviv University; Tel Aviv Israel
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17
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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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18
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Evans JM, Cox ML, Huska J, Li F, Gaitero L, Guo LT, Casal ML, Granzier HL, Shelton GD, Clark LA. Exome sequencing reveals a nebulin nonsense mutation in a dog model of nemaline myopathy. Mamm Genome 2016; 27:495-502. [PMID: 27215641 DOI: 10.1007/s00335-016-9644-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Accepted: 05/06/2016] [Indexed: 12/25/2022]
Abstract
Nemaline myopathy (NM) is a congenital muscle disorder associated with muscle weakness, hypotonia, and rod bodies in the skeletal muscle fibers. Mutations in 10 genes have been implicated in human NM, but spontaneous cases in dogs have not been genetically characterized. We identified a novel recessive myopathy in a family of line-bred American bulldogs (ABDs); rod bodies in muscle biopsies established this as NM. Using SNP profiles from the nuclear family, we evaluated inheritance patterns at candidate loci and prioritized TNNT1 and NEB for further investigation. Whole exome sequencing of the dam, two affected littermates, and an unaffected littermate revealed a nonsense mutation in NEB (g.52734272 C>A, S8042X). Whole tissue gel electrophoresis and western blots confirmed a lack of full-length NEB in affected tissues, suggesting nonsense-mediated decay. The pathogenic variant was absent from 120 dogs of 24 other breeds and 100 unrelated ABDs, suggesting that it occurred recently and may be private to the family. This study presents the first molecularly characterized large animal model of NM, which could provide new opportunities for therapeutic approaches.
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Affiliation(s)
- Jacquelyn M Evans
- Department of Genetics and Biochemistry, Clemson University, Clemson, SC, 29634, USA
| | - Melissa L Cox
- CAG GmbH - Center for Animal Genetics, Tübingen, Germany
| | - Jonathan Huska
- Ontario Veterinary College, University of Guelph, Guelph, ON, Canada
| | - Frank Li
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ, 85724, USA
| | - Luis Gaitero
- Ontario Veterinary College, University of Guelph, Guelph, ON, Canada
| | - Ling T Guo
- Department of Pathology, University of California San Diego, La Jolla, CA, 92093, USA
| | - Margaret L Casal
- School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Henk L Granzier
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ, 85724, USA
| | - G Diane Shelton
- Department of Pathology, University of California San Diego, La Jolla, CA, 92093, USA.
| | - Leigh Anne Clark
- Department of Genetics and Biochemistry, Clemson University, Clemson, SC, 29634, USA.
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19
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Investigation of Pathogenic Genes in Chinese sporadic Hypertrophic Cardiomyopathy Patients by Whole Exome Sequencing. Sci Rep 2015; 5:16609. [PMID: 26573135 PMCID: PMC4647833 DOI: 10.1038/srep16609] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Accepted: 10/16/2015] [Indexed: 11/08/2022] Open
Abstract
Hypertrophic cardiomyopathy (HCM) is a cardiovascular disease with high heterogeneity. Limited knowledge concerning the genetic background of nearly 40% HCM cases indicates there is a clear need for further investigation to explore the genetic pathogenesis of the disease. In this study, we undertook a whole exome sequencing (WES) approach to identify novel candidate genes and mutations associated with HCM. The cohort consisted of 74 unrelated patients with sporadic HCM (sHCM) previously determined to be negative for mutations in eight sarcomere genes. The results showed that 7 of 74 patients (9.5%) had damaging mutations in 43 known HCM disease genes. Furthermore, after analysis combining the Transmission and De novo Association (TADA) program and the ToppGene program, 10 putative genes gained priority. A thorough review of public databases and related literature revealed that there is strong supporting evidence for most of the genes playing roles in various aspects of heart development. Findings from recent studies suggest that the putative and known disease genes converge on three functional pathways: sarcomere function, calcium signaling and metabolism pathway. This study illustrates the benefit of WES, in combination with rare variant analysis tools, in providing valuable insight into the genetic etiology of a heterogeneous sporadic disease.
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20
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Todd EJ, Yau KS, Ong R, Slee J, McGillivray G, Barnett CP, Haliloglu G, Talim B, Akcoren Z, Kariminejad A, Cairns A, Clarke NF, Freckmann ML, Romero NB, Williams D, Sewry CA, Colley A, Ryan MM, Kiraly-Borri C, Sivadorai P, Allcock RJN, Beeson D, Maxwell S, Davis MR, Laing NG, Ravenscroft G. Next generation sequencing in a large cohort of patients presenting with neuromuscular disease before or at birth. Orphanet J Rare Dis 2015; 10:148. [PMID: 26578207 PMCID: PMC4650299 DOI: 10.1186/s13023-015-0364-0] [Citation(s) in RCA: 87] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Accepted: 11/02/2015] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND Fetal akinesia/hypokinesia, arthrogryposis and severe congenital myopathies are heterogeneous conditions usually presenting before or at birth. Although numerous causative genes have been identified for each of these disease groups, in many cases a specific genetic diagnosis remains elusive. Due to the emergence of next generation sequencing, virtually the entire coding region of an individual's DNA can now be analysed through "whole" exome sequencing, enabling almost all known and novel disease genes to be investigated for disorders such as these. METHODS Genomic DNA samples from 45 patients with fetal akinesia/hypokinesia, arthrogryposis or severe congenital myopathies from 38 unrelated families were subjected to next generation sequencing. Clinical features and diagnoses for each patient were supplied by referring clinicians. Genomic DNA was used for either whole exome sequencing or a custom-designed neuromuscular sub-exomic supercapture array containing 277 genes responsible for various neuromuscular diseases. Candidate disease-causing variants were investigated and confirmed using Sanger sequencing. Some of the cases within this cohort study have been published previously as separate studies. RESULTS A conclusive genetic diagnosis was achieved for 18 of the 38 families. Within this cohort, mutations were found in eight previously known neuromuscular disease genes (CHRND, CHNRG, ECEL1, GBE1, MTM1, MYH3, NEB and RYR1) and four novel neuromuscular disease genes were identified and have been published as separate reports (GPR126, KLHL40, KLHL41 and SPEG). In addition, novel mutations were identified in CHRND, KLHL40, NEB and RYR1. Autosomal dominant, autosomal recessive, X-linked, and de novo modes of inheritance were observed. CONCLUSIONS By using next generation sequencing on a cohort of 38 unrelated families with fetal akinesia/hypokinesia, arthrogryposis, or severe congenital myopathy we therefore obtained a genetic diagnosis for 47% of families. This study highlights the power and capacity of next generation sequencing (i) to determine the aetiology of genetically heterogeneous neuromuscular diseases, (ii) to identify novel disease genes in small pedigrees or isolated cases and (iii) to refine the interplay between genetic diagnosis and clinical evaluation and management.
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Affiliation(s)
- Emily J Todd
- Harry Perkins Institute of Medical Research and the Centre for Medical Research, University of Western Australia, QQ Block, 6 Verdun Street, Nedlands, 6009, , WA, Australia.
| | - Kyle S Yau
- Harry Perkins Institute of Medical Research and the Centre for Medical Research, University of Western Australia, QQ Block, 6 Verdun Street, Nedlands, 6009, , WA, Australia.
| | - Royston Ong
- Harry Perkins Institute of Medical Research and the Centre for Medical Research, University of Western Australia, QQ Block, 6 Verdun Street, Nedlands, 6009, , WA, Australia.
| | - Jennie Slee
- Genetic Services of Western Australia, King Edward Memorial Hospital, Perth, 6000, , WA, Australia.
| | - George McGillivray
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute, The Royal Children's Hospital, Parkville, 3052, , VIC, Australia.
| | - Christopher P Barnett
- Paediatric and Reproductive Genetics Unit, South Australia Clinical Genetics Service, Women's and Children's Hospital, North Adelaide, 5006, , SA, Australia.
| | - Goknur Haliloglu
- Department of Pediatric Neurology, Hacettepe University Children's Hospital, Ankara, 06100, Turkey.
| | - Beril Talim
- Pediatric Pathology Unit, Hacettepe University Children's Hospital, Ankara, 06100, Turkey.
| | - Zuhal Akcoren
- Pediatric Pathology Unit, Hacettepe University Children's Hospital, Ankara, 06100, Turkey.
| | - Ariana Kariminejad
- Kariminejad-Najmabadi Pathology and Genetics Centre, Tehran, 14656, Iran.
| | - Anita Cairns
- Royal Children's Hospital, Herston Road, Herson, 4029, , QLD, Australia.
| | - Nigel F Clarke
- Institute for Neuroscience and Muscle Research, The Children's Hospital at Westmead, Sydney, 2145, , NSW, Australia. .,Discipline of Paediatrics and Child Health, University of Sydney, Sydney, 2006, , NSW, Australia.
| | | | - Norma B Romero
- Unitè de Morphologie Neuromusculaire, Institut de Myologie, Institut National de la Santè et de la Recherche Mèdicale, Paris, 75651, France.
| | - Denise Williams
- Dubowitz Neuromuscular Centre, UCL Institute of Child Health, London, WC1N 1EH, UK. .,Wolfson Centre for Neuromuscular Disorders, RJAH Orthopaedic Hospital, Oswestry, SY10 7AG, UK.
| | - Caroline A Sewry
- Dubowitz Neuromuscular Centre, UCL Institute of Child Health, London, WC1N 1EH, UK. .,Wolfson Centre for Neuromuscular Disorders, RJAH Orthopaedic Hospital, Oswestry, SY10 7AG, UK.
| | - Alison Colley
- Department of Clinical Genetics, South Western Sydney Local Health District, Liverpool, 1871, , NSW, Australia.
| | - Monique M Ryan
- Department of Neurology, The Royal Children's Hospital, Melbourne, 3000, , VIC, Australia.
| | - Cathy Kiraly-Borri
- Genetic Services of Western Australia, Princess Margaret Hospital for Children and King Edward Memorial Hospital for Women, Subiaco, 6008, , WA, Australia.
| | - Padma Sivadorai
- Department of Diagnostic Genomics, Pathwest, QEII Medical Centre, Nedlands, 6009, , WA, Australia.
| | - Richard J N Allcock
- Lotterywest State Biomedical Facility Genomics and School of Pathology and Laboratory Medicine, University of Western Australia, Perth, 6000, , WA, Australia.
| | - David Beeson
- Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, OX3 9DS, UK.
| | - Susan Maxwell
- Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, OX3 9DS, UK.
| | - Mark R Davis
- Department of Diagnostic Genomics, Pathwest, QEII Medical Centre, Nedlands, 6009, , WA, Australia.
| | - Nigel G Laing
- Harry Perkins Institute of Medical Research and the Centre for Medical Research, University of Western Australia, QQ Block, 6 Verdun Street, Nedlands, 6009, , WA, Australia. .,Department of Diagnostic Genomics, Pathwest, QEII Medical Centre, Nedlands, 6009, , WA, Australia.
| | - Gianina Ravenscroft
- Harry Perkins Institute of Medical Research and the Centre for Medical Research, University of Western Australia, QQ Block, 6 Verdun Street, Nedlands, 6009, , WA, Australia.
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21
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A recurrent copy number variation of the NEB triplicate region: only revealed by the targeted nemaline myopathy CGH array. Eur J Hum Genet 2015. [PMID: 26197980 DOI: 10.1038/ejhg.2015.166] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Recently, new large variants have been identified in the nebulin gene (NEB) causing nemaline myopathy (NM). NM constitutes a heterogeneous group of disorders among the congenital myopathies, and disease-causing variants in NEB are a main cause of the recessively inherited form of NM. NEB consists of 183 exons and it includes homologous sequences such as a 32-kb triplicate region (TRI), where eight exons are repeated three times (exons 82-89, 90-97, 98-105). In human, the normal copy number of NEB TRI is six (three copies in each allele). Recently, we described a custom NM-CGH microarray designed to detect copy number variations (CNVs) in the known NM genes. The array has now been updated to include all the currently known 10 NM genes. The NM-CGH array is superior in detecting CNVs, especially of the NEB TRI, that is not included in the exome capture kits. To date, we have studied 266 samples from 196 NM families using the NM-CGH microarray, and identified a novel recurrent NEB TRI variation in 13% (26/196) of the families and in 10% of the controls (6/60). An analysis of the breakpoints revealed adjacent repeat elements, which are known to predispose for rearrangements such as CNVs. The control CNV samples deviate only one copy from the normal six copies, whereas the NM samples include CNVs of up to four additional copies. Based on this study, NEB seems to tolerate deviations of one TRI copy, whereas addition of two or more copies might be pathogenic.
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22
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Lehtokari VL, Kiiski K, Sandaradura SA, Laporte J, Repo P, Frey JA, Donner K, Marttila M, Saunders C, Barth PG, den Dunnen JT, Beggs AH, Clarke NF, North KN, Laing NG, Romero NB, Winder TL, Pelin K, Wallgren-Pettersson C. Mutation update: the spectra of nebulin variants and associated myopathies. Hum Mutat 2015; 35:1418-26. [PMID: 25205138 DOI: 10.1002/humu.22693] [Citation(s) in RCA: 102] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2014] [Accepted: 08/29/2014] [Indexed: 12/23/2022]
Abstract
A mutation update on the nebulin gene (NEB) is necessary because of recent developments in analysis methodology, the identification of increasing numbers and novel types of variants, and a widening in the spectrum of clinical and histological phenotypes associated with this gigantic, 183 exons containing gene. Recessive pathogenic variants in NEB are the major cause of nemaline myopathy (NM), one of the most common congenital myopathies. Moreover, pathogenic NEB variants have been identified in core-rod myopathy and in distal myopathies. In this update, we present the disease-causing variants in NEB in 159 families, 143 families with NM, and 16 families with NM-related myopathies. Eighty-eight families are presented here for the first time. We summarize 86 previously published and 126 unpublished variants identified in NEB. Furthermore, we have analyzed the NEB variants deposited in the Exome Variant Server (http://evs.gs.washington.edu/EVS/), identifying that pathogenic variants are a minor fraction of all coding variants (∼7%). This indicates that nebulin tolerates substantial changes in its amino acid sequence, providing an explanation as to why variants in such a large gene result in relatively rare disorders. Lastly, we discuss the difficulties of drawing reliable genotype-phenotype correlations in NEB-associated disease.
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Affiliation(s)
- Vilma-Lotta Lehtokari
- The Folkhälsan Institute of Genetics and the Department of Medical Genetics, Haartman Institute, University of Helsinki, Helsinki, Finland
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23
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Ahram DF, Grozdanic SD, Kecova H, Henkes A, Collin RWJ, Kuehn MH. Variants in Nebulin (NEB) Are Linked to the Development of Familial Primary Angle Closure Glaucoma in Basset Hounds. PLoS One 2015; 10:e0126660. [PMID: 25938837 PMCID: PMC4418656 DOI: 10.1371/journal.pone.0126660] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Accepted: 04/06/2015] [Indexed: 12/12/2022] Open
Abstract
Several dog breeds are susceptible to developing primary angle closure glaucoma (PACG), which suggests a genetic basis for the disease. We have identified a four-generation Basset Hound pedigree with characteristic autosomal recessive PACG that closely recapitulates PACG in humans. Our aim is to utilize gene mapping and whole exome sequencing approaches to identify PACG-causing sequence variants in the Basset. Extensive clinical phenotyping of all pedigree members was conducted. SNP-chip genotyping was carried out in 9 affected and 15 unaffected pedigree members. Two-point and multipoint linkage analyses of genome-wide SNP data were performed using Superlink-Online SNP-1.1 and a locus was mapped to chromosome 19q with a maximum LOD score of 3.24. The locus contains 12 Ensemble predicted canine genes and is syntenic to a region on chromosome 2 in the human genome. Using exome-sequencing analysis, a possibly damaging, non-synonymous variant in the gene Nebulin (NEB) was found to segregate with PACG which alters a phylogenetically conserved Lysine residue. The association of this variants with PACG was confirmed in a secondary cohort of unrelated Basset Hounds (p = 3.4 × 10-4, OR = 15.3 for homozygosity). Nebulin, a protein that promotes the contractile function of sarcomeres, was found to be prominently expressed in the ciliary muscles of the anterior segment. Our findings may provide insight into the molecular mechanisms that underlie PACG. The phenotypic similarities of disease presentation in dogs and humans may enable the translation of findings made in this study to patients with PACG.
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Affiliation(s)
- Dina F. Ahram
- Department of Ophthalmology and Visual Sciences, The University of Iowa, Iowa City, IA, United States of America
| | | | - Helga Kecova
- Animal Eye Consultants of Iowa, North Liberty, IA, United States of America
| | - Arjen Henkes
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Rob W. J. Collin
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
- Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Markus H. Kuehn
- Department of Ophthalmology and Visual Sciences, The University of Iowa, Iowa City, IA, United States of America
- * E-mail:
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24
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Nowak KJ, Davis MR, Wallgren-Pettersson C, Lamont PJ, Laing NG. Clinical utility gene card for: Nemaline myopathy - update 2015. Eur J Hum Genet 2015; 23:ejhg201512. [PMID: 25712079 DOI: 10.1038/ejhg.2015.12] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Revised: 12/16/2014] [Accepted: 01/13/2015] [Indexed: 11/09/2022] Open
Affiliation(s)
- Kristen J Nowak
- Centre for Medical Research, The University of Western Australia and the Harry Perkins Institute of Medical Research, QEII Medical Centre, Nedlands, Western Australia, Australia
| | - Mark R Davis
- Department of Diagnostic Genomics, Neurogenetics Laboratory, QEII Medical Centre, Nedlands, Western Australia, Australia
| | - Carina Wallgren-Pettersson
- Department of Medical Genetics, The Folkhälsan Institute of Genetics, Haartman Institute, University of Helsinki, Helsinki, Finland
| | - Phillipa J Lamont
- Department of Diagnostic Genomics, Neurogenetics Laboratory, QEII Medical Centre, Nedlands, Western Australia, Australia
| | - Nigel G Laing
- Centre for Medical Research, The University of Western Australia and the Harry Perkins Institute of Medical Research, QEII Medical Centre, Nedlands, Western Australia, Australia
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25
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Colombo I, Scoto M, Manzur AY, Robb SA, Maggi L, Gowda V, Cullup T, Yau M, Phadke R, Sewry C, Jungbluth H, Muntoni F. Congenital myopathies: Natural history of a large pediatric cohort. Neurology 2014; 84:28-35. [PMID: 25428687 DOI: 10.1212/wnl.0000000000001110] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
OBJECTIVE To assess the natural history of congenital myopathies (CMs) due to different genotypes. METHODS Retrospective cross-sectional study based on case-note review of 125 patients affected by CM, followed at a single pediatric neuromuscular center, between 1984 and 2012. RESULTS Genetic characterization was achieved in 99 of 125 cases (79.2%), with RYR1 most frequently implicated (44/125). Neonatal/infantile onset was observed in 76%. At birth, 30.4% required respiratory support, and 25.2% nasogastric feeding. Twelve percent died, mainly within the first year, associated with mutations in ACTA1, MTM1, or KLHL40. All RYR1-mutated cases survived and did not require long-term ventilator support including those with severe neonatal onset; however, recessive cases were more likely to require gastrostomy insertion (p = 0.0028) compared with dominant cases. Independent ambulation was achieved in 74.1% of all patients; 62.9% were late walkers. Among ambulant patients, 9% eventually became wheelchair-dependent. Scoliosis of variable severity was reported in 40%, with 1/3 of (both ambulant and nonambulant) patients requiring surgery. Bulbar involvement was present in 46.4% and required gastrostomy placement in 28.8% (at a mean age of 2.7 years). Respiratory impairment of variable severity was a feature in 64.1%; approximately half of these patients required nocturnal noninvasive ventilation due to respiratory failure (at a mean age of 8.5 years). CONCLUSIONS We describe the long-term outcome of a large cohort of patients with CMs. While overall course is stable, we demonstrate a wide clinical spectrum with motor deterioration in a subset of cases. Severity in the neonatal/infantile period is critical for survival, with clear genotype-phenotype correlations that may inform future counseling.
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Affiliation(s)
- Irene Colombo
- From the Dubowitz Neuromuscular Centre and MRC Centre for Neuromuscular Disorders (I.C., M.S., A.Y.M., S.A.R., V.G., C.S., F.M.), University College London Institute of Child Health and Great Ormond Street Hospital for Children, London, UK; Neuromuscular Unit (I.C.), Department of Neurological Sciences, IRCCS Foundation Cà Granda, Ospedale Maggiore Policlinico, Dino Ferrari Centre, Milan, University of Milan; Muscle Pathology and Neuroimmunology Unit (L.M.), Foundation IRCCS Neurological Institute C. Besta, Milan, Italy; DNA Laboratory (T.C., M.Y.), GSTS Pathology, Guy's Hospital, London; University College London Department of Neurology (R.P.), National Hospital for Neurology and Neurosurgery, London; Wolfson Centre for Inherited Neuromuscular Diseases RJAH (C.S.), Oswestry; Department of Paediatric Neurology (H.J.), Evelina Children's Hospital, London; Randall Division for Cell and Molecular Biophysics (H.J.), Muscle Signalling Section, King's College, London; and Clinical Neuroscience Division (H.J.), IoP, London, UK
| | - Mariacristina Scoto
- From the Dubowitz Neuromuscular Centre and MRC Centre for Neuromuscular Disorders (I.C., M.S., A.Y.M., S.A.R., V.G., C.S., F.M.), University College London Institute of Child Health and Great Ormond Street Hospital for Children, London, UK; Neuromuscular Unit (I.C.), Department of Neurological Sciences, IRCCS Foundation Cà Granda, Ospedale Maggiore Policlinico, Dino Ferrari Centre, Milan, University of Milan; Muscle Pathology and Neuroimmunology Unit (L.M.), Foundation IRCCS Neurological Institute C. Besta, Milan, Italy; DNA Laboratory (T.C., M.Y.), GSTS Pathology, Guy's Hospital, London; University College London Department of Neurology (R.P.), National Hospital for Neurology and Neurosurgery, London; Wolfson Centre for Inherited Neuromuscular Diseases RJAH (C.S.), Oswestry; Department of Paediatric Neurology (H.J.), Evelina Children's Hospital, London; Randall Division for Cell and Molecular Biophysics (H.J.), Muscle Signalling Section, King's College, London; and Clinical Neuroscience Division (H.J.), IoP, London, UK
| | - Adnan Y Manzur
- From the Dubowitz Neuromuscular Centre and MRC Centre for Neuromuscular Disorders (I.C., M.S., A.Y.M., S.A.R., V.G., C.S., F.M.), University College London Institute of Child Health and Great Ormond Street Hospital for Children, London, UK; Neuromuscular Unit (I.C.), Department of Neurological Sciences, IRCCS Foundation Cà Granda, Ospedale Maggiore Policlinico, Dino Ferrari Centre, Milan, University of Milan; Muscle Pathology and Neuroimmunology Unit (L.M.), Foundation IRCCS Neurological Institute C. Besta, Milan, Italy; DNA Laboratory (T.C., M.Y.), GSTS Pathology, Guy's Hospital, London; University College London Department of Neurology (R.P.), National Hospital for Neurology and Neurosurgery, London; Wolfson Centre for Inherited Neuromuscular Diseases RJAH (C.S.), Oswestry; Department of Paediatric Neurology (H.J.), Evelina Children's Hospital, London; Randall Division for Cell and Molecular Biophysics (H.J.), Muscle Signalling Section, King's College, London; and Clinical Neuroscience Division (H.J.), IoP, London, UK
| | - Stephanie A Robb
- From the Dubowitz Neuromuscular Centre and MRC Centre for Neuromuscular Disorders (I.C., M.S., A.Y.M., S.A.R., V.G., C.S., F.M.), University College London Institute of Child Health and Great Ormond Street Hospital for Children, London, UK; Neuromuscular Unit (I.C.), Department of Neurological Sciences, IRCCS Foundation Cà Granda, Ospedale Maggiore Policlinico, Dino Ferrari Centre, Milan, University of Milan; Muscle Pathology and Neuroimmunology Unit (L.M.), Foundation IRCCS Neurological Institute C. Besta, Milan, Italy; DNA Laboratory (T.C., M.Y.), GSTS Pathology, Guy's Hospital, London; University College London Department of Neurology (R.P.), National Hospital for Neurology and Neurosurgery, London; Wolfson Centre for Inherited Neuromuscular Diseases RJAH (C.S.), Oswestry; Department of Paediatric Neurology (H.J.), Evelina Children's Hospital, London; Randall Division for Cell and Molecular Biophysics (H.J.), Muscle Signalling Section, King's College, London; and Clinical Neuroscience Division (H.J.), IoP, London, UK
| | - Lorenzo Maggi
- From the Dubowitz Neuromuscular Centre and MRC Centre for Neuromuscular Disorders (I.C., M.S., A.Y.M., S.A.R., V.G., C.S., F.M.), University College London Institute of Child Health and Great Ormond Street Hospital for Children, London, UK; Neuromuscular Unit (I.C.), Department of Neurological Sciences, IRCCS Foundation Cà Granda, Ospedale Maggiore Policlinico, Dino Ferrari Centre, Milan, University of Milan; Muscle Pathology and Neuroimmunology Unit (L.M.), Foundation IRCCS Neurological Institute C. Besta, Milan, Italy; DNA Laboratory (T.C., M.Y.), GSTS Pathology, Guy's Hospital, London; University College London Department of Neurology (R.P.), National Hospital for Neurology and Neurosurgery, London; Wolfson Centre for Inherited Neuromuscular Diseases RJAH (C.S.), Oswestry; Department of Paediatric Neurology (H.J.), Evelina Children's Hospital, London; Randall Division for Cell and Molecular Biophysics (H.J.), Muscle Signalling Section, King's College, London; and Clinical Neuroscience Division (H.J.), IoP, London, UK
| | - Vasantha Gowda
- From the Dubowitz Neuromuscular Centre and MRC Centre for Neuromuscular Disorders (I.C., M.S., A.Y.M., S.A.R., V.G., C.S., F.M.), University College London Institute of Child Health and Great Ormond Street Hospital for Children, London, UK; Neuromuscular Unit (I.C.), Department of Neurological Sciences, IRCCS Foundation Cà Granda, Ospedale Maggiore Policlinico, Dino Ferrari Centre, Milan, University of Milan; Muscle Pathology and Neuroimmunology Unit (L.M.), Foundation IRCCS Neurological Institute C. Besta, Milan, Italy; DNA Laboratory (T.C., M.Y.), GSTS Pathology, Guy's Hospital, London; University College London Department of Neurology (R.P.), National Hospital for Neurology and Neurosurgery, London; Wolfson Centre for Inherited Neuromuscular Diseases RJAH (C.S.), Oswestry; Department of Paediatric Neurology (H.J.), Evelina Children's Hospital, London; Randall Division for Cell and Molecular Biophysics (H.J.), Muscle Signalling Section, King's College, London; and Clinical Neuroscience Division (H.J.), IoP, London, UK
| | - Thomas Cullup
- From the Dubowitz Neuromuscular Centre and MRC Centre for Neuromuscular Disorders (I.C., M.S., A.Y.M., S.A.R., V.G., C.S., F.M.), University College London Institute of Child Health and Great Ormond Street Hospital for Children, London, UK; Neuromuscular Unit (I.C.), Department of Neurological Sciences, IRCCS Foundation Cà Granda, Ospedale Maggiore Policlinico, Dino Ferrari Centre, Milan, University of Milan; Muscle Pathology and Neuroimmunology Unit (L.M.), Foundation IRCCS Neurological Institute C. Besta, Milan, Italy; DNA Laboratory (T.C., M.Y.), GSTS Pathology, Guy's Hospital, London; University College London Department of Neurology (R.P.), National Hospital for Neurology and Neurosurgery, London; Wolfson Centre for Inherited Neuromuscular Diseases RJAH (C.S.), Oswestry; Department of Paediatric Neurology (H.J.), Evelina Children's Hospital, London; Randall Division for Cell and Molecular Biophysics (H.J.), Muscle Signalling Section, King's College, London; and Clinical Neuroscience Division (H.J.), IoP, London, UK
| | - Michael Yau
- From the Dubowitz Neuromuscular Centre and MRC Centre for Neuromuscular Disorders (I.C., M.S., A.Y.M., S.A.R., V.G., C.S., F.M.), University College London Institute of Child Health and Great Ormond Street Hospital for Children, London, UK; Neuromuscular Unit (I.C.), Department of Neurological Sciences, IRCCS Foundation Cà Granda, Ospedale Maggiore Policlinico, Dino Ferrari Centre, Milan, University of Milan; Muscle Pathology and Neuroimmunology Unit (L.M.), Foundation IRCCS Neurological Institute C. Besta, Milan, Italy; DNA Laboratory (T.C., M.Y.), GSTS Pathology, Guy's Hospital, London; University College London Department of Neurology (R.P.), National Hospital for Neurology and Neurosurgery, London; Wolfson Centre for Inherited Neuromuscular Diseases RJAH (C.S.), Oswestry; Department of Paediatric Neurology (H.J.), Evelina Children's Hospital, London; Randall Division for Cell and Molecular Biophysics (H.J.), Muscle Signalling Section, King's College, London; and Clinical Neuroscience Division (H.J.), IoP, London, UK
| | - Rahul Phadke
- From the Dubowitz Neuromuscular Centre and MRC Centre for Neuromuscular Disorders (I.C., M.S., A.Y.M., S.A.R., V.G., C.S., F.M.), University College London Institute of Child Health and Great Ormond Street Hospital for Children, London, UK; Neuromuscular Unit (I.C.), Department of Neurological Sciences, IRCCS Foundation Cà Granda, Ospedale Maggiore Policlinico, Dino Ferrari Centre, Milan, University of Milan; Muscle Pathology and Neuroimmunology Unit (L.M.), Foundation IRCCS Neurological Institute C. Besta, Milan, Italy; DNA Laboratory (T.C., M.Y.), GSTS Pathology, Guy's Hospital, London; University College London Department of Neurology (R.P.), National Hospital for Neurology and Neurosurgery, London; Wolfson Centre for Inherited Neuromuscular Diseases RJAH (C.S.), Oswestry; Department of Paediatric Neurology (H.J.), Evelina Children's Hospital, London; Randall Division for Cell and Molecular Biophysics (H.J.), Muscle Signalling Section, King's College, London; and Clinical Neuroscience Division (H.J.), IoP, London, UK
| | - Caroline Sewry
- From the Dubowitz Neuromuscular Centre and MRC Centre for Neuromuscular Disorders (I.C., M.S., A.Y.M., S.A.R., V.G., C.S., F.M.), University College London Institute of Child Health and Great Ormond Street Hospital for Children, London, UK; Neuromuscular Unit (I.C.), Department of Neurological Sciences, IRCCS Foundation Cà Granda, Ospedale Maggiore Policlinico, Dino Ferrari Centre, Milan, University of Milan; Muscle Pathology and Neuroimmunology Unit (L.M.), Foundation IRCCS Neurological Institute C. Besta, Milan, Italy; DNA Laboratory (T.C., M.Y.), GSTS Pathology, Guy's Hospital, London; University College London Department of Neurology (R.P.), National Hospital for Neurology and Neurosurgery, London; Wolfson Centre for Inherited Neuromuscular Diseases RJAH (C.S.), Oswestry; Department of Paediatric Neurology (H.J.), Evelina Children's Hospital, London; Randall Division for Cell and Molecular Biophysics (H.J.), Muscle Signalling Section, King's College, London; and Clinical Neuroscience Division (H.J.), IoP, London, UK
| | - Heinz Jungbluth
- From the Dubowitz Neuromuscular Centre and MRC Centre for Neuromuscular Disorders (I.C., M.S., A.Y.M., S.A.R., V.G., C.S., F.M.), University College London Institute of Child Health and Great Ormond Street Hospital for Children, London, UK; Neuromuscular Unit (I.C.), Department of Neurological Sciences, IRCCS Foundation Cà Granda, Ospedale Maggiore Policlinico, Dino Ferrari Centre, Milan, University of Milan; Muscle Pathology and Neuroimmunology Unit (L.M.), Foundation IRCCS Neurological Institute C. Besta, Milan, Italy; DNA Laboratory (T.C., M.Y.), GSTS Pathology, Guy's Hospital, London; University College London Department of Neurology (R.P.), National Hospital for Neurology and Neurosurgery, London; Wolfson Centre for Inherited Neuromuscular Diseases RJAH (C.S.), Oswestry; Department of Paediatric Neurology (H.J.), Evelina Children's Hospital, London; Randall Division for Cell and Molecular Biophysics (H.J.), Muscle Signalling Section, King's College, London; and Clinical Neuroscience Division (H.J.), IoP, London, UK
| | - Francesco Muntoni
- From the Dubowitz Neuromuscular Centre and MRC Centre for Neuromuscular Disorders (I.C., M.S., A.Y.M., S.A.R., V.G., C.S., F.M.), University College London Institute of Child Health and Great Ormond Street Hospital for Children, London, UK; Neuromuscular Unit (I.C.), Department of Neurological Sciences, IRCCS Foundation Cà Granda, Ospedale Maggiore Policlinico, Dino Ferrari Centre, Milan, University of Milan; Muscle Pathology and Neuroimmunology Unit (L.M.), Foundation IRCCS Neurological Institute C. Besta, Milan, Italy; DNA Laboratory (T.C., M.Y.), GSTS Pathology, Guy's Hospital, London; University College London Department of Neurology (R.P.), National Hospital for Neurology and Neurosurgery, London; Wolfson Centre for Inherited Neuromuscular Diseases RJAH (C.S.), Oswestry; Department of Paediatric Neurology (H.J.), Evelina Children's Hospital, London; Randall Division for Cell and Molecular Biophysics (H.J.), Muscle Signalling Section, King's College, London; and Clinical Neuroscience Division (H.J.), IoP, London, UK.
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26
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Hoffman JD, Park JJ, Schreiber-Agus N, Kornreich R, Tanner AK, Keiles S, Friedman KJ, Heim RA. The Ashkenazi Jewish carrier screening panel: evolution, status quo, and disparities. Prenat Diagn 2014; 34:1161-7. [DOI: 10.1002/pd.4446] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Revised: 06/18/2014] [Accepted: 06/27/2014] [Indexed: 11/06/2022]
Affiliation(s)
- Jodi D. Hoffman
- Division of Genetics; Floating Hospital for Children, Tufts Medical Center; Boston MA USA
| | - Jessica J. Park
- Medical School; Tufts University School of Medicine; Boston MA USA
| | - Nicole Schreiber-Agus
- Program for Jewish Genetic Health; Albert Einstein College of Medicine; Bronx NY USA
| | - Ruth Kornreich
- Mount Sinai Genetic Testing Laboratory; Icahn School of Medicine at Mount Sinai; New York NY USA
| | | | | | | | - Ruth A. Heim
- Integrated Genetics, Laboratory Corporation of America® Holdings; Westborough MA USA
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27
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Abstract
PURPOSE OF REVIEW This article reviews recent advances in the understanding of nemaline myopathy, with a focus on the genetic basis of the disorder, histology, and pathogenesis. RECENT FINDINGS Pathogenic mutations have been identified in eight genes and there is evidence of further genetic heterogeneity in nemaline myopathy. Clinical presentation, histological features on skeletal muscle biopsy, and pattern of changes on muscle MRI may guide prioritization of molecular genetic testing. It is anticipated that use of new technologies such as whole exome sequencing and comparative genomic hybridization will increase the number of genes associated with nemaline myopathy and the proportion of patients in whom the genetic basis of the disorder is identified. Single fiber studies and animal models continue to add to understanding of the pathogenesis of this disorder. Current management focuses on supportive treatment; however, encouraging advances are emerging for the future. SUMMARY Recent advances in understanding of nemaline myopathy have important implications for clinical practice and for genetic diagnosis of patients with nemaline myopathy.
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North KN, Wang CH, Clarke N, Jungbluth H, Vainzof M, Dowling JJ, Amburgey K, Quijano-Roy S, Beggs AH, Sewry C, Laing NG, Bönnemann CG. Approach to the diagnosis of congenital myopathies. Neuromuscul Disord 2014; 24:97-116. [PMID: 24456932 PMCID: PMC5257342 DOI: 10.1016/j.nmd.2013.11.003] [Citation(s) in RCA: 187] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Revised: 11/06/2013] [Accepted: 11/08/2013] [Indexed: 10/26/2022]
Abstract
Over the past decade there have been major advances in defining the genetic basis of the majority of congenital myopathy subtypes. However the relationship between each congenital myopathy, defined on histological grounds, and the genetic cause is complex. Many of the congenital myopathies are due to mutations in more than one gene, and mutations in the same gene can cause different muscle pathologies. The International Standard of Care Committee for Congenital Myopathies performed a literature review and consulted a group of experts in the field to develop a summary of (1) the key features common to all forms of congenital myopathy and (2) the specific features that help to discriminate between the different genetic subtypes. The consensus statement was refined by two rounds of on-line survey, and a three-day workshop. This consensus statement provides guidelines to the physician assessing the infant or child with hypotonia and weakness. We summarise the clinical features that are most suggestive of a congenital myopathy, the major differential diagnoses and the features on clinical examination, investigations, muscle pathology and muscle imaging that are suggestive of a specific genetic diagnosis to assist in prioritisation of genetic testing of known genes. As next generation sequencing becomes increasingly used as a diagnostic tool in clinical practise, these guidelines will assist in determining which sequence variations are likely to be pathogenic.
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Affiliation(s)
- Kathryn N North
- Murdoch Childrens Research Institute, Royal Children's Hospital, Flemington Road, Parkville, Melbourne, Victoria 3052, Australia; Institute for Neuroscience and Muscle Research, The Children's Hospital at Westmead, University of Sydney, Sydney, Australia.
| | - Ching H Wang
- Driscoll Children's Hospital, Corpus Christi, TX, United States
| | - Nigel Clarke
- Institute for Neuroscience and Muscle Research, The Children's Hospital at Westmead, University of Sydney, Sydney, Australia
| | - Heinz Jungbluth
- Evelina Children's Hospital, Department of Paediatric Neurology, London, United Kingdom; Randall Division for Cell and Molecular Biophysics, Muscle Signalling Section, King's College, London, United Kingdom; Clinical Neuroscience Division, IoP, London, United Kingdom
| | - Mariz Vainzof
- Human Genome Research Center, University of Sao Paulo, Sao Paulo, Brazil
| | - James J Dowling
- Division of Neurology, Department of Paediatrics, Hospital for Sick Children, Toronto, ON, Canada
| | - Kimberly Amburgey
- Division of Neurology, Department of Paediatrics, Hospital for Sick Children, Toronto, ON, Canada
| | - Susana Quijano-Roy
- Department of Pediatrics, Garches Neuromuscular Reference Center (GNMH), APHP Raymond Poincare University Hospital (UVSQ), Garches, France
| | - Alan H Beggs
- Children's Hospital Boston, Boston, MA, United States
| | - Caroline Sewry
- Dubowitz Neuromuscular Centre, London, United Kingdom; Wolfson Centre of Inherited Neuromuscular Diseases, RJAH Orthopaedic Hospital, Oswestry, United Kingdom
| | - Nigel G Laing
- Centre for Medical Research, University of Western Australia and Harry Perkins Institute of Medical Research, QQ Building, QEII Medical Centre, Nedlands, Western Australia 6009, Australia
| | - Carsten G Bönnemann
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, Bethesda, MD, United States
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29
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Scoto M, Cullup T, Cirak S, Yau S, Manzur AY, Feng L, Jacques TS, Anderson G, Abbs S, Sewry C, Jungbluth H, Muntoni F. Nebulin (NEB) mutations in a childhood onset distal myopathy with rods and cores uncovered by next generation sequencing. Eur J Hum Genet 2013; 21:1249-52. [PMID: 23443021 PMCID: PMC3798838 DOI: 10.1038/ejhg.2013.31] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2012] [Revised: 01/16/2013] [Accepted: 01/24/2013] [Indexed: 11/09/2022] Open
Abstract
Recessive nebulin (NEB) mutations are a common cause of nemaline myopathy (NM), typically characterized by generalized weakness of early-onset and nemaline rods on muscle biopsy. Exceptional adult cases with additional cores and an isolated distal weakness have been reported. The large NEB gene with 183 exons has been an obstacle for the genetic work-up. Here we report a childhood-onset case with distal weakness and a core-rod myopathy, associated with recessive NEB mutations identified by next generation sequencing (NGS). This 6-year-old boy presented with a history of gross-motor difficulties following a normal early development. He had distal leg weakness with bilateral foot drop, as well as axial muscle weakness, scoliosis and spinal rigidity; additionally he required nocturnal respiratory support. Muscle magnetic resonance (MR) imaging showed distal involvement in the medial and anterior compartment of the lower leg. A muscle biopsy featured both rods and cores. Initial targeted testing identified a heterozygous Nebulin exon 55 deletion. Further analysis using NGS revealed a frameshifting 4 bp duplication, c.24372_24375dup (P.Val8126fs), on the opposite allele. This case illustrates that NEB mutations can cause childhood onset distal NM, with additional cores on muscle biopsy and proves the diagnostic utility of NGS for myopathies, particularly when large genes are implicated.
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Affiliation(s)
| | - Thomas Cullup
- DNA Laboratory, GSTS Pathology, Guy's Hospital, London, UK
| | - Sebahattin Cirak
- Dubowitz Neuromuscular Centre, UCL Institute of Child Health, London, UK
| | - Shu Yau
- DNA Laboratory, GSTS Pathology, Guy's Hospital, London, UK
| | - Adnan Y Manzur
- Dubowitz Neuromuscular Centre, UCL Institute of Child Health, London, UK
| | - Lucy Feng
- Dubowitz Neuromuscular Centre, UCL Institute of Child Health, London, UK
| | - Thomas S Jacques
- Neural Development Unit, UCL Institute of Child Health, London, UK
- Department of Histopathology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Glenn Anderson
- Department of Histopathology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Stephen Abbs
- DNA Laboratory, GSTS Pathology, Guy's Hospital, London, UK
| | - Caroline Sewry
- Dubowitz Neuromuscular Centre, UCL Institute of Child Health, London, UK
- Centre for Inherited Neuromuscular Diseases, RJAH Orthopaedic NHS Foundation Trust, Oswestry, UK
| | - Heinz Jungbluth
- Clinical Neuroscience Division, IOP, King's College London, London, UK
- Department of Paediatric Neurology – Neuromuscular Service, Evelina Children's Hospital, London, UK
| | - Francesco Muntoni
- Dubowitz Neuromuscular Centre, UCL Institute of Child Health, London, UK
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Ottenheijm CAC, Buck D, de Winter JM, Ferrara C, Piroddi N, Tesi C, Jasper JR, Malik FI, Meng H, Stienen GJM, Beggs AH, Labeit S, Poggesi C, Lawlor MW, Granzier H. Deleting exon 55 from the nebulin gene induces severe muscle weakness in a mouse model for nemaline myopathy. ACTA ACUST UNITED AC 2013; 136:1718-31. [PMID: 23715096 DOI: 10.1093/brain/awt113] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Nebulin--a giant sarcomeric protein--plays a pivotal role in skeletal muscle contractility by specifying thin filament length and function. Although mutations in the gene encoding nebulin (NEB) are a frequent cause of nemaline myopathy, the most common non-dystrophic congenital myopathy, the mechanisms by which mutations in NEB cause muscle weakness remain largely unknown. To better understand these mechanisms, we have generated a mouse model in which Neb exon 55 is deleted (Neb(ΔExon55)) to replicate a founder mutation seen frequently in patients with nemaline myopathy with Ashkenazi Jewish heritage. Neb(ΔExon55) mice are born close to Mendelian ratios, but show growth retardation after birth. Electron microscopy studies show nemaline bodies--a hallmark feature of nemaline myopathy--in muscle fibres from Neb(ΔExon55) mice. Western blotting studies with nebulin-specific antibodies reveal reduced nebulin levels in muscle from Neb(ΔExon55) mice, and immunofluorescence confocal microscopy studies with tropomodulin antibodies and phalloidin reveal that thin filament length is significantly reduced. In line with reduced thin filament length, the maximal force generating capacity of permeabilized muscle fibres and single myofibrils is reduced in Neb(ΔExon55) mice with a more pronounced reduction at longer sarcomere lengths. Finally, in Neb(ΔExon55) mice the regulation of contraction is impaired, as evidenced by marked changes in crossbridge cycling kinetics and by a reduction of the calcium sensitivity of force generation. A novel drug that facilitates calcium binding to the thin filament significantly augmented the calcium sensitivity of submaximal force to levels that exceed those observed in untreated control muscle. In conclusion, we have characterized the first nebulin-based nemaline myopathy model, which recapitulates important features of the phenotype observed in patients harbouring this particular mutation, and which has severe muscle weakness caused by thin filament dysfunction.
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Affiliation(s)
- Coen A C Ottenheijm
- Department of Physiology, VU University Medical Centre, Amsterdam, The Netherlands
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Kiiski K, Laari L, Lehtokari VL, Lunkka-Hytönen M, Angelini C, Petty R, Hackman P, Wallgren-Pettersson C, Pelin K. Targeted array comparative genomic hybridization--a new diagnostic tool for the detection of large copy number variations in nemaline myopathy-causing genes. Neuromuscul Disord 2012; 23:56-65. [PMID: 23010307 DOI: 10.1016/j.nmd.2012.07.007] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2012] [Accepted: 07/16/2012] [Indexed: 11/28/2022]
Abstract
Nemaline myopathy (NM) constitutes a heterogeneous group of congenital myopathies. Mutations in the nebulin gene (NEB) are the main cause of recessively inherited NM. NEB is one of the most largest genes in human. To date, 68 NEB mutations, mainly small deletions or point mutations have been published. The only large mutation characterized is the 2.5 kb deletion of exon 55 in the Ashkenazi Jewish population. To investigate any copy number variations in this enormous gene, we designed a novel custom comparative genomic hybridization microarray, NM-CGH, targeted towards the seven known genes causative for NM. During the validation of the NM-CGH array we identified two novel deletions in two different families. The first is the largest deletion characterized in NEB to date, (∼53 kb) encompassing 24 exons. The second deletion (1 kb) covers two exons. In both families, the copy number change was the second mutation to be characterized and shown to have been inherited from one of the healthy carrier parents. In addition to these novel mutations, copy number variation was identified in four samples in three families in the triplicate region of NEB. We conclude that this method appears promising for the detection of copy number variations in NEB.
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Affiliation(s)
- K Kiiski
- The Folkhälsan Institute of Genetics and the Department of Medical Genetics, University of Helsinki, Haartman Institute, Helsinki, Finland.
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Ottenheijm CAC, Granzier H, Labeit S. The sarcomeric protein nebulin: another multifunctional giant in charge of muscle strength optimization. Front Physiol 2012; 3:37. [PMID: 22375125 PMCID: PMC3286824 DOI: 10.3389/fphys.2012.00037] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2012] [Accepted: 02/09/2012] [Indexed: 12/01/2022] Open
Abstract
The sliding filament model of the sarcomere was developed more than half a century ago. This model, consisting only of thin and thick filaments, has been successful in explaining many, but not all, features of skeletal muscle. Work during the 1980s revealed the existence of two additional filaments: the giant filamentous proteins titin and nebulin. Whereas the role of titin rapidly progressed, nebulin’s role in muscle structure and function remained long nebulous. An important feature of muscle structure and function that has remained relatively obscure concerns the mechanisms that are involved in regulating thin filament length. Filament length is an important aspect of muscle function as force production is proportional to the amount of overlap between thick and thin filaments. Recent advances, due in part to the generation of nebulin KO models, reveal that nebulin plays an important role in the regulation of thin filament length, most likely by stabilizing F-actin assemblies. Another structural feature of skeletal muscle that has been incompletely understood concerns the mechanisms involved in maintaining Z-disk structure and the regular lateral alignment of adjacent sarcomeres during contraction. Recent studies indicate that nebulin is part of a protein complex that mechanically links adjacent myofibrils. In addition to these structural roles in support of myofibrillar force generation, nebulin has been also shown to regulate directly muscle contraction at the level of individual crossbridges: cycling kinetics and the calcium sensitivity of force producing crossbridges is enhanced in the presence of nebulin. Thus, these recent data all point to nebulin being important for muscle force optimization. Consequently, muscle weakness as the lead symptom develops in the case of patients with nemaline myopathy that have mutations in the nebulin gene. Here, we discuss these important novel insights into the role of nebulin in skeletal muscle function.
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Affiliation(s)
- Coen A C Ottenheijm
- Department of Physiology, Institute for Cardiovascular Research, VU University Medical Center Amsterdam, Netherlands
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Yonath H, Reznik-Wolf H, Berkenstadt M, Eisenberg-Barzilai S, Lehtokari VL, Wallgren-Pettersson C, Mehta L, Achiron R, Gilboa Y, Polak-Charcon S, Winder T, Frydman M, Pras E. Carrier state for the nebulin exon 55 deletion and abnormal prenatal ultrasound findings as potential signs of nemaline myopathy. Prenat Diagn 2012; 32:70-4. [DOI: 10.1002/pd.2905] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Hagith Yonath
- Danek Gertner Institute of Human Genetics; Sheba Medical Center; Ramat Gan Israel
- Sackler School of Medicine; Tel Aviv University; Tel Aviv Israel
| | - Haike Reznik-Wolf
- Danek Gertner Institute of Human Genetics; Sheba Medical Center; Ramat Gan Israel
| | - Michal Berkenstadt
- Danek Gertner Institute of Human Genetics; Sheba Medical Center; Ramat Gan Israel
| | | | - Vilma-Lotta Lehtokari
- Folkhälsan Insitute of Genetics and Department of Medical Genetics, Haartman Institute; University of Helsinki; Helsinki Finland
| | - Carina Wallgren-Pettersson
- Folkhälsan Insitute of Genetics and Department of Medical Genetics, Haartman Institute; University of Helsinki; Helsinki Finland
| | - Lakshmi Mehta
- Department of Genetics & Genomic Sciences; Mount Sinai School of Medicine; New York NY USA
| | - Reuven Achiron
- Department of Obstetrics and Gynecology; Sheba Medical Center; Ramat Gan Israel
- Sackler School of Medicine; Tel Aviv University; Tel Aviv Israel
| | - Yinon Gilboa
- Department of Obstetrics and Gynecology; Sheba Medical Center; Ramat Gan Israel
- Sackler School of Medicine; Tel Aviv University; Tel Aviv Israel
| | - Sylvie Polak-Charcon
- Department of Pathology; Sheba Medical Center; Ramat Gan Israel
- Sackler School of Medicine; Tel Aviv University; Tel Aviv Israel
| | | | - Moshe Frydman
- Danek Gertner Institute of Human Genetics; Sheba Medical Center; Ramat Gan Israel
- Sackler School of Medicine; Tel Aviv University; Tel Aviv Israel
| | - Elon Pras
- Danek Gertner Institute of Human Genetics; Sheba Medical Center; Ramat Gan Israel
- Sackler School of Medicine; Tel Aviv University; Tel Aviv Israel
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Fedick A, Su J, Treff NR. Development of TaqMan allelic discrimination based genotyping of large DNA deletions. Genomics 2012; 99:127-31. [PMID: 22281206 DOI: 10.1016/j.ygeno.2012.01.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2011] [Revised: 12/08/2011] [Accepted: 01/09/2012] [Indexed: 10/14/2022]
Abstract
The high prevalence of genetic diseases resulting from gross deletions has highlighted a need for a quick, simple, and reliable method of genotyping these mutations. Here, we developed a novel strategy for applying TaqMan allelic discrimination to accurately genotype 3 different large deletions in a high-throughput manner. Allelic discrimination has previously been used to genotype frame shift and point mutations, and small insertions or deletions six base pairs in length, but not large deletions. The assays designed here recognize a 2502 base pair deletion in the Nebulin (NEB) gene that results in Nemaline Myopathy, a 308,769 base pair deletion in the Gap Junction Protein, beta 6 (GJB6) gene that causes Hearing Loss, and a 6433 base pair deletion in the Mucolipin 1 (MCOLN1) gene responsible for causing Mucolipidosis IV Disease. This methodology may also be successfully applied to high throughput genotyping of other large deletions.
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Affiliation(s)
- Anastasia Fedick
- Department of Molecular Genetics, Microbiology, and Immunology, UMDNJ-Robert Wood Johnson Medical School, Piscataway, NJ, USA.
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36
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Lehtokari VL, Pelin K, Herczegfalvi A, Karcagi V, Pouget J, Franques J, Pellissier JF, Figarella-Branger D, von der Hagen M, Huebner A, Schoser B, Lochmüller H, Wallgren-Pettersson C. Nemaline myopathy caused by mutations in the nebulin gene may present as a distal myopathy. Neuromuscul Disord 2011; 21:556-62. [DOI: 10.1016/j.nmd.2011.05.012] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2011] [Revised: 05/10/2011] [Accepted: 05/27/2011] [Indexed: 11/26/2022]
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Lawlor MW, Ottenheijm CA, Lehtokari VL, Cho K, Pelin K, Wallgren-Pettersson C, Granzier H, Beggs AH. Novel mutations in NEB cause abnormal nebulin expression and markedly impaired muscle force generation in severe nemaline myopathy. Skelet Muscle 2011; 1:23. [PMID: 21798101 PMCID: PMC3156646 DOI: 10.1186/2044-5040-1-23] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2011] [Accepted: 06/20/2011] [Indexed: 12/04/2022] Open
Abstract
Background Nemaline myopathy (NM) is a congenital muscle disease associated with weakness and the presence of nemaline bodies (rods) in muscle fibers. Mutations in seven genes have been associated with NM, but the most commonly mutated gene is nebulin (NEB), which is thought to account for roughly 50% of cases. Results We describe two siblings with severe NM, arthrogryposis and neonatal death caused by two novel NEB mutations: a point mutation in intron 13 and a frameshift mutation in exon 81. Levels of detectable nebulin protein were significantly lower than those in normal control muscle biopsies or those from patients with less severe NM due to deletion of NEB exon 55. Mechanical studies of skinned myofibers revealed marked impairment of force development, with an increase in tension cost. Conclusions Our findings demonstrate that the mechanical phenotype of severe NM is the consequence of mutations that severely reduce nebulin protein levels and suggest that the level of nebulin expression may correlate with the severity of disease.
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Affiliation(s)
- Michael W Lawlor
- Division of Genetics and Program in Genomics, The Manton Center for Orphan Disease Research, Children's Hospital Boston, Harvard Medical School, 300 Longwood Avenue, CLSB 15026, Boston, MA 02115, USA
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Scott SA, Edelmann L, Liu L, Luo M, Desnick RJ, Kornreich R. Experience with carrier screening and prenatal diagnosis for 16 Ashkenazi Jewish genetic diseases. Hum Mutat 2010; 31:1240-50. [PMID: 20672374 DOI: 10.1002/humu.21327] [Citation(s) in RCA: 116] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The success of prenatal carrier screening as a disease prevention strategy in the Ashkenazi Jewish (AJ) population has driven the expansion of screening panels as disease-causing founder mutations have been identified. However, the carrier frequencies of many of these mutations have not been reported in large AJ cohorts. We determined the carrier frequencies of over 100 mutations for 16 recessive disorders in the New York metropolitan area AJ population. Among the 100% AJ-descended individuals, screening for 16 disorders resulted in ∼1 in 3.3 being a carrier for one disease and ∼1 in 24 for two diseases. The carrier frequencies ranged from 0.066 (1 in 15.2; Gaucher disease) to 0.006 (1 in 168; nemaline myopathy), which averaged ∼15% higher than those for all screenees. Importantly, over 95% of screenees chose to be screened for all possible AJ diseases, including disorders with lower carrier frequencies and/or detectability. Carrier screening also identified rare individuals homozygous for disease-causing mutations who had previously unrecognized clinical manifestations. Additionally, prenatal testing results and experience for all 16 disorders (n = 574) are reported. Together, these data indicate the general acceptance, carrier frequencies, and prenatal testing results for an expanded panel of 16 diseases in the AJ population.
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Affiliation(s)
- Stuart A Scott
- Department of Genetics and Genomic Sciences, Mount Sinai School of Medicine of New York University, New York, NY 10029, USA
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39
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Labeit S, Ottenheijm CAC, Granzier H. Nebulin, a major player in muscle health and disease. FASEB J 2010; 25:822-9. [PMID: 21115852 DOI: 10.1096/fj.10-157412] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Nebulin is a giant 600- to 900-kDa filamentous protein that is an integral component of the skeletal muscle thin filament. Its functions have remained largely nebulous because of its large size and the difficulty in extracting nebulin in a native state from muscle. Recent improvements in the field, especially the development of knockout mouse models deficient in nebulin (NEB-KO mice), indicate now that nebulin performs a surprisingly wide range of functions. In addition to a major role in thin-filament length specification, nebulin also functions in the regulation of muscle contraction, as indicated by the findings that muscle fibers deficient in nebulin have a higher tension cost, and develop less force due to reduced myofilament calcium sensitivity and altered crossbridge cycling kinetics. In addition, the function of nebulin extends to a role in calcium homeostasis. These novel functions indicate that nebulin might have evolved in vertebrate skeletal muscles to develop high levels of muscle force efficiently. Finally, the NEB-KO mouse models also highlight the role of nebulin in the assembly and alignment of the Z disks. Notably, rapid progress in understanding the roles of nebulin in vivo provides clinically important insights into how nebulin deficiency in patients with nemaline myopathy contributes to debilitating muscle weakness.
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Affiliation(s)
- Siegfried Labeit
- Department of Integrative Pathophysiology, Universitätsmedizin Mannheim, University of Heidelberg, Mannheim, Germany.
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40
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Abstract
Ashkenazi Jewish genetic screening has expanded significantly in the past 4 decades. Individuals of Eastern European (Ashkenazi) Jewish (AJ) descent are at increased risk of having offspring with particular genetic diseases that have significant morbidity and mortality. In addition, there are some disorders, such as cystic fibrosis, for which northern European Caucasians are at comparable risk with those of an AJ background. Carrier screening for many of these Jewish genetic disorders has become standard of care. As technology advances, so does the number of disorders for which screening is available. Thus, we need to continue to be cognizant of informed consent, test sensitivity, confidentiality, prenatal diagnosis, preimplantation genetic screening, and public health concerns regarding testing.
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Altered myofilament function depresses force generation in patients with nebulin-based nemaline myopathy (NEM2). J Struct Biol 2009; 170:334-43. [PMID: 19944167 DOI: 10.1016/j.jsb.2009.11.013] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2009] [Revised: 11/18/2009] [Accepted: 11/22/2009] [Indexed: 11/22/2022]
Abstract
Nemaline myopathy (NM), the most common non-dystrophic congenital myopathy, is clinically characterized by muscle weakness. However, the mechanisms underlying this weakness are poorly understood. Here, we studied the contractile phenotype of skeletal muscle from NM patients with nebulin mutations (NEM2). SDS-PAGE and Western blotting studies revealed markedly reduced nebulin protein levels in muscle from NM patients, whereas levels of other thin filament-based proteins were not significantly altered. Muscle mechanics studies indicated significantly reduced calcium sensitivity of force generation in NM muscle fibers compared to control fibers. In addition, we found slower rate constant of force redevelopment, as well as increased tension cost, in NM compared to control fibers, indicating that in NM muscle the rate of cross-bridge attachment is reduced, whereas the rate of cross-bridge detachment is increased. The resulting reduced fraction of force generating cross-bridges is expected to greatly impair the force generating capacity of muscle from NM patients. Thus, the present study provides important novel insights into the pathogenesis of muscle weakness in nebulin-based NM.
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42
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Kontrogianni-Konstantopoulos A, Ackermann MA, Bowman AL, Yap SV, Bloch RJ. Muscle giants: molecular scaffolds in sarcomerogenesis. Physiol Rev 2009; 89:1217-67. [PMID: 19789381 PMCID: PMC3076733 DOI: 10.1152/physrev.00017.2009] [Citation(s) in RCA: 186] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Myofibrillogenesis in striated muscles is a highly complex process that depends on the coordinated assembly and integration of a large number of contractile, cytoskeletal, and signaling proteins into regular arrays, the sarcomeres. It is also associated with the stereotypical assembly of the sarcoplasmic reticulum and the transverse tubules around each sarcomere. Three giant, muscle-specific proteins, titin (3-4 MDa), nebulin (600-800 kDa), and obscurin (approximately 720-900 kDa), have been proposed to play important roles in the assembly and stabilization of sarcomeres. There is a large amount of data showing that each of these molecules interacts with several to many different protein ligands, regulating their activity and localizing them to particular sites within or surrounding sarcomeres. Consistent with this, mutations in each of these proteins have been linked to skeletal and cardiac myopathies or to muscular dystrophies. The evidence that any of them plays a role as a "molecular template," "molecular blueprint," or "molecular ruler" is less definitive, however. Here we review the structure and function of titin, nebulin, and obscurin, with the literature supporting a role for them as scaffolding molecules and the contradictory evidence regarding their roles as molecular guides in sarcomerogenesis.
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43
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Emery A. Rare genetic disorders in certain populations. Neuromuscul Disord 2009; 19:307. [DOI: 10.1016/j.nmd.2009.04.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2009] [Indexed: 11/17/2022]
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Ottenheijm CAC, Witt CC, Stienen GJ, Labeit S, Beggs AH, Granzier H. Thin filament length dysregulation contributes to muscle weakness in nemaline myopathy patients with nebulin deficiency. Hum Mol Genet 2009; 18:2359-69. [PMID: 19346529 DOI: 10.1093/hmg/ddp168] [Citation(s) in RCA: 121] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Nemaline myopathy (NM) is the most common non-dystrophic congenital myopathy. Clinically the most important feature of NM is muscle weakness; however, the mechanisms underlying this weakness are poorly understood. Here, we studied the muscular phenotype of NM patients with a well-defined nebulin mutation (NM-NEB), using a multidisciplinary approach to study thin filament length regulation and muscle contractile performance. SDS-PAGE and western blotting revealed greatly reduced nebulin levels in skeletal muscle of NM-NEB patients, with the most prominent reduction at nebulin's N-terminal end. Muscle mechanical studies indicated approximately 60% reduced force generating capacity of NM-NEB muscle and a leftward-shift of the force-sarcomere length relation in NM-NEB muscle fibers. This indicates that the mechanism for the force reduction is likely to include shorter and non-uniform thin filament lengths in NM-NEB muscle compared with control muscle. Immunofluorescence confocal microscopy and electron microscopy studies indicated that average thin filament length is reduced from approximately 1.3 microm in control muscle to approximately 0.75 microm in NM-NEB muscle. Thus, the present study is the first to show a distinct genotype-functional phenotype correlation in patients with NM due to a nebulin mutation, and provides evidence for the notion that dysregulated thin filament length contributes to muscle weakness in NM patients with nebulin mutations. Furthermore, a striking similarity between the contractile and structural phenotypes of nebulin-deficient mouse muscle and human NM-NEB muscle was observed, indicating that the nebulin knockout model is well suited for elucidating the functional basis of muscle weakness in NM and for the development of treatment strategies.
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Affiliation(s)
- Coen A C Ottenheijm
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ 85724, USA
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45
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46
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The exon 55 deletion in the nebulin gene--one single founder mutation with world-wide occurrence. Neuromuscul Disord 2009; 19:179-81. [PMID: 19232495 DOI: 10.1016/j.nmd.2008.12.001] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2008] [Revised: 11/20/2008] [Accepted: 12/01/2008] [Indexed: 11/21/2022]
Abstract
In 2004, Anderson et al. reported a homozygous 2502 bp deletion including exon 55 of the nebulin gene in five Ashkenazi Jewish probands with nemaline myopathy. We determined the occurrence of this deletion in a world-wide series of 355 nemaline myopathy probands with no previously known mutation in other genes and found the mutation in 14 probands, two of whom represented families previously ascertained by Anderson et al. Two of the families were not of known Ashkenazi Jewish descent but they had the haplotype known to segregate with this mutation. In all but two of eight homozygous patients, the clinical picture was more severe than in typical nemaline myopathy.
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Pelin K, Wallgren-Pettersson C. Nebulin—A Giant Chameleon. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2008. [DOI: 10.1007/978-0-387-84847-1_3] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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48
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Fares F, Badarneh K, Abosaleh M, Harari-Shaham A, Diukman R, David M. Carrier frequency of autosomal-recessive disorders in the Ashkenazi Jewish population: should the rationale for mutation choice for screening be reevaluated? Prenat Diagn 2008; 28:236-41. [DOI: 10.1002/pd.1943] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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49
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Ilkovski B. Investigations into the Pathobiology of Thin-Filament Myopathies. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2008; 642:55-65. [DOI: 10.1007/978-0-387-84847-1_5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
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Weiss K, Shapira Y, Glick B, Lerman-Sagie T, Shahar E, Goez H, Kutai M, Nevo Y. Congenital myopathies in Israeli families. J Child Neurol 2007; 22:732-6. [PMID: 17641259 DOI: 10.1177/0883073807304193] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The clinical features of 37 patients from 32 Israeli families with congenital myopathies evaluated between 1983 and 2004 are described: 13 children were diagnosed with congenital fiber type disproportion, 10 had myotubular myopathy, 7 had nemaline myopathy, 5 had central core disease, 1 had actin myopathy, and 1 had multi-minicore disease. There were 7 families (22%) that had parental consanguinity, and 4 families (12%) had more than 1 patient with congenital myopathy. Of the patients, 31 (84%) presented with clinical symptoms before 4 months of age, and 6 children (16%) presented after 1 year of age. Thirteen children (35%) had a severe phenotype with chronic ventilatory dependence or mortality before the age of 11 years. Facial weakness was associated with a severe phenotype. There was a high rate of a severe clinical phenotype in patients with myotubular myopathy (60%) and in patients with nemaline myopathy (57%), whereas in patients with congenital fiber type disproportion and in patients with central core disease, the proportion of a severe phenotype was lower (23% and 0%, respectively).
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