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Belhassen I, Laroussi S, Sakka S, Rekik S, Lahkim L, Dammak M, Authier FJ, Mhiri C. Dysferlinopathy in Tunisia: clinical spectrum, genetic background and prognostic profile. Neuromuscul Disord 2023; 33:718-727. [PMID: 37716854 DOI: 10.1016/j.nmd.2023.08.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Revised: 08/08/2023] [Accepted: 08/13/2023] [Indexed: 09/18/2023]
Abstract
Dysferlinopathy is a rare group of hereditary muscular dystrophy with an autosomal recessive mode of inheritance caused by a mutation in the DYSF gene. It encodes for the dysferlin protein, which has a crucial role in multiple cellular processes, including muscle fiber membrane repair. This deficit has heterogeneous clinical presentations. In this study, we collected 20 Tunisian patients with a sex ratio of 1 and a median age of 50.5 years old (Interquartile range (IQR) = [36,5-54,75]). They were followed for periods ranging from 5 to 48 years. The median age at onset was 17 years old (IQR = [16,8-28,4]). Five major phenotypes were identified: Limb-girdle muscular dystrophy (LGMDR2) (35%), a proximodistal phenotype (35%), Miyoshi myopathy (10%), Distal myopathy with anterior tibial onset (DMAT) (10%), and asymptomatic HyperCKemia (10%). At the last evaluation, more than half of patients (55%) were on wheelchair. Loss of ambulation occurred generally during the fourth decade. After 20 years of disease progression, two patients with a proximodistal phenotype (10%) developed dilated cardiomyopathy and mitral valve regurgitation. Restrictive respiratory syndrome was observed in three patients (DMAT: 1 patient, proximodistal phenotype: 1 patient, LGMDR2: 1 patient). Genetic study disclosed five mutations. We observed clinical heterogeneity between families and even within the same family. Disease progression was mainly slow to intermediate regardless of the phenotype.
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Affiliation(s)
- Ikhlass Belhassen
- Laboratory of Neurogenetics, Parkinson's Disease and Cerebrovascular Disease (LR-12-SP-19), Habib Bourguiba University Hospital, University of Sfax, Tunisia
| | - Sirine Laroussi
- Laboratory of Neurogenetics, Parkinson's Disease and Cerebrovascular Disease (LR-12-SP-19), Habib Bourguiba University Hospital, University of Sfax, Tunisia; Department of Neurology, Habib Bourguiba University Hospital, Faculty of Medicine of Sfax, Sfax, Tunisia.
| | - Salma Sakka
- Department of Neurology, Habib Bourguiba University Hospital, Faculty of Medicine of Sfax, Sfax, Tunisia
| | - Sabrine Rekik
- Laboratory of Neurogenetics, Parkinson's Disease and Cerebrovascular Disease (LR-12-SP-19), Habib Bourguiba University Hospital, University of Sfax, Tunisia
| | - Laila Lahkim
- Pathology Laboratory, Habib Bourguiba University Hospital, Sfax, Tunisia
| | - Mariem Dammak
- Laboratory of Neurogenetics, Parkinson's Disease and Cerebrovascular Disease (LR-12-SP-19), Habib Bourguiba University Hospital, University of Sfax, Tunisia; Clinical Investigation Center, Habib Bourguiba University Hospital, Sfax, Tunisia; Department of Neurology, Habib Bourguiba University Hospital, Faculty of Medicine of Sfax, Sfax, Tunisia
| | | | - Chokri Mhiri
- Laboratory of Neurogenetics, Parkinson's Disease and Cerebrovascular Disease (LR-12-SP-19), Habib Bourguiba University Hospital, University of Sfax, Tunisia; Clinical Investigation Center, Habib Bourguiba University Hospital, Sfax, Tunisia; Department of Neurology, Habib Bourguiba University Hospital, Faculty of Medicine of Sfax, Sfax, Tunisia
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Okubo M, Iida A, Hayashi S, Mori-Yoshimura M, Oya Y, Watanabe A, Arahata H, El Sherif R, Noguchi S, Nishino I. Three novel recessive DYSF mutations identified in three patients with muscular dystrophy, limb-girdle, type 2B. J Neurol Sci 2018; 395:169-171. [PMID: 30366248 DOI: 10.1016/j.jns.2018.10.015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Revised: 09/26/2018] [Accepted: 10/15/2018] [Indexed: 11/28/2022]
Affiliation(s)
- Mariko Okubo
- Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan; Department of Pediatrics, Graduate School of Medicine and Faculty of Medicine, The University Tokyo, Tokyo, Japan
| | - Aritoshi Iida
- Department of Clinical Genome Analysis, Medical Genome Center, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Shinichiro Hayashi
- Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Madoka Mori-Yoshimura
- Department of Neurology, National Center Hospital, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Yasushi Oya
- Department of Neurology, National Center Hospital, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Akihiro Watanabe
- Department of Neurology, National Hospital Organization Omuta Hospital, Fukuoka, Japan
| | - Hajime Arahata
- Department of Neurology, National Hospital Organization Omuta Hospital, Fukuoka, Japan
| | | | - Satoru Noguchi
- Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Ichizo Nishino
- Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan; Department of Clinical Genome Analysis, Medical Genome Center, National Center of Neurology and Psychiatry, Tokyo, Japan.
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3
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Lukyanenko V, Muriel JM, Bloch RJ. Coupling of excitation to Ca 2+ release is modulated by dysferlin. J Physiol 2017; 595:5191-5207. [PMID: 28568606 DOI: 10.1113/jp274515] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Accepted: 05/16/2017] [Indexed: 12/16/2022] Open
Abstract
KEY POINTS Dysferlin, the protein missing in limb girdle muscular dystrophy 2B and Miyoshi myopathy, concentrates in transverse tubules of skeletal muscle, where it stabilizes voltage-induced Ca2+ transients against loss after osmotic shock injury (OSI). Local expression of dysferlin in dysferlin-null myofibres increases transient amplitude to control levels and protects them from loss after OSI. Inhibitors of ryanodine receptors (RyR1) and L-type Ca2+ channels protect voltage-induced Ca2+ transients from loss; thus both proteins play a role in injury in dysferlin's absence. Effects of Ca2+ -free medium and S107, which inhibits SR Ca2+ leak, suggest the SR as the primary source of Ca2+ responsible for the loss of the Ca2+ transient upon injury. Ca2+ waves were induced by OSI and suppressed by exogenous dysferlin. We conclude that dysferlin prevents injury-induced SR Ca2+ leak. ABSTRACT Dysferlin concentrates in the transverse tubules of skeletal muscle and stabilizes Ca2+ transients when muscle fibres are subjected to osmotic shock injury (OSI). We show here that voltage-induced Ca2+ transients elicited in dysferlin-null A/J myofibres were smaller than control A/WySnJ fibres. Regional expression of Venus-dysferlin chimeras in A/J fibres restored the full amplitude of the Ca2+ transients and protected against OSI. We also show that drugs that target ryanodine receptors (RyR1: dantrolene, tetracaine, S107) and L-type Ca2+ channels (LTCCs: nifedipine, verapamil, diltiazem) prevented the decrease in Ca2+ transients in A/J fibres following OSI. Diltiazem specifically increased transients by ∼20% in uninjured A/J fibres, restoring them to control values. The fact that both RyR1s and LTCCs were involved in OSI-induced damage suggests that damage is mediated by increased Ca2+ leak from the sarcoplasmic reticulum (SR) through the RyR1. Congruent with this, injured A/J fibres produced Ca2+ sparks and Ca2+ waves. S107 (a stabilizer of RyR1-FK506 binding protein coupling that reduces Ca2+ leak) or local expression of Venus-dysferlin prevented OSI-induced Ca2+ waves. Our data suggest that dysferlin modulates SR Ca2+ release in skeletal muscle, and that in its absence OSI causes increased RyR1-mediated Ca2+ leak from the SR into the cytoplasm.
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Affiliation(s)
- Valeriy Lukyanenko
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Joaquin M Muriel
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Robert J Bloch
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
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4
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Discordant manifestation in brothers with Miyoshi myopathy. J Neurol Sci 2017; 373:86-87. [PMID: 28131235 DOI: 10.1016/j.jns.2016.12.032] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Revised: 11/29/2016] [Accepted: 12/19/2016] [Indexed: 11/20/2022]
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Fanin M, Angelini C. Progress and challenges in diagnosis of dysferlinopathy. Muscle Nerve 2016; 54:821-835. [DOI: 10.1002/mus.25367] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/04/2016] [Indexed: 01/22/2023]
Affiliation(s)
- Marina Fanin
- Department of Neurosciences; University of Padova; Biomedical Campus “Pietro d'Abano”, via Giuseppe Orus 2B 35129 Padova Italy
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Woudt L, Di Capua GA, Krahn M, Castiglioni C, Hughes R, Campero M, Trangulao A, González-Hormazábal P, Godoy-Herrera R, Lévy N, Urtizberea JA, Jara L, Bevilacqua JA. Toward an objective measure of functional disability in dysferlinopathy. Muscle Nerve 2015; 53:49-57. [DOI: 10.1002/mus.24685] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/13/2015] [Indexed: 11/06/2022]
Affiliation(s)
- Lisanne Woudt
- Unidad Neuromuscular; Departamento de Neurología y Neurocirugía; Hospital Clínico Universidad de Chile, Santos Dumont 999, 2do. piso; Sector E. Independencia 8380456 Santiago Chile
| | - Gabriella A. Di Capua
- Programa de Genética Humana; Instituto de Ciencias Biomédicas (ICBM), Facultad de Medicina, Universidad de Chile; Santiago Chile
| | - Martin Krahn
- Aix Marseille Université; INSERM, Medical Genetics and Functional Genomics; Unité Mixte de Recherche_S 910 Marseille France
- Assistance Publique - Hôpitaux de Marseille; Département de Génétique Médicale; Hôpital Timone Enfants; Marseille France
| | - Claudia Castiglioni
- Unidad de Neurología; Departamento de Pediatría; Clínica Las Condes; Santiago Chile
| | - Ricardo Hughes
- Unidad Neuromuscular; Departamento de Neurología y Neurocirugía; Hospital Clínico Universidad de Chile, Santos Dumont 999, 2do. piso; Sector E. Independencia 8380456 Santiago Chile
| | - Mario Campero
- Unidad Neuromuscular; Departamento de Neurología y Neurocirugía; Hospital Clínico Universidad de Chile, Santos Dumont 999, 2do. piso; Sector E. Independencia 8380456 Santiago Chile
| | - Alejandra Trangulao
- Programa Anatomía y Biología del Desarrollo; Instituto de Ciencias Biomédicas (ICBM), Facultad de Medicina, Universidad de Chile; Santiago Chile
| | - Patricio González-Hormazábal
- Programa de Genética Humana; Instituto de Ciencias Biomédicas (ICBM), Facultad de Medicina, Universidad de Chile; Santiago Chile
| | - Raúl Godoy-Herrera
- Programa de Genética Humana; Instituto de Ciencias Biomédicas (ICBM), Facultad de Medicina, Universidad de Chile; Santiago Chile
| | - Nicolas Lévy
- Aix Marseille Université; INSERM, Medical Genetics and Functional Genomics; Unité Mixte de Recherche_S 910 Marseille France
- Assistance Publique - Hôpitaux de Marseille; Département de Génétique Médicale; Hôpital Timone Enfants; Marseille France
| | - Jon Andoni Urtizberea
- Unité Neuromusculaire, Hôpital Marin de Hendaye; Assistance Publique - Hôpitaux de Paris Hendaye France
| | - Lilian Jara
- Programa de Genética Humana; Instituto de Ciencias Biomédicas (ICBM), Facultad de Medicina, Universidad de Chile; Santiago Chile
| | - Jorge A. Bevilacqua
- Unidad Neuromuscular; Departamento de Neurología y Neurocirugía; Hospital Clínico Universidad de Chile, Santos Dumont 999, 2do. piso; Sector E. Independencia 8380456 Santiago Chile
- Programa Anatomía y Biología del Desarrollo; Instituto de Ciencias Biomédicas (ICBM), Facultad de Medicina, Universidad de Chile; Santiago Chile
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Mahmood OA, Jiang X, Zhang Q. Limb-girdle muscular dystrophy subtypes: First-reported cohort from northeastern China. Neural Regen Res 2014; 8:1907-18. [PMID: 25206500 PMCID: PMC4145977 DOI: 10.3969/j.issn.1673-5374.2013.20.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2013] [Accepted: 06/25/2013] [Indexed: 12/02/2022] Open
Abstract
The relative frequencies of different subtypes of limb-girdle muscular dystrophies vary widely among different populations. We estimated the percentage of limb-girdle muscular dystrophy subtypes in Chinese people based on 68 patients with limb-girdle muscular dystrophy from the Myology Clinic, Neurology Department, First Hospital of Jilin University, China. A diagnosis of calpainopathy was made in 12 cases (17%), and dysferlin deficiency in 10 cases (15%). Two biopsies revealed α-sarcoglycan deficiency (3%), and two others revealed a lack of caveolin-3 (3%). A diagnosis of unclassified limb-girdle muscular dystrophy was made in the remaining patients (62%). The appearances of calpain 3- and dysferlin-deficient biopsies were similar, though rimmed vacuoles were unique to dysferlinopathy, while inflammatory infiltrates were present in both these limb-girdle muscular dystrophy type 2D biopsies. Macrophages were detected in seven dysferlinopathy biopsies. The results of this study suggest that the distribution of limb-girdle muscular dystrophy subtypes in the Han Chinese population is similar to that reported in the West. The less necrotic, regenerating and inflammatory appearance of limb-girdle muscular dystrophy type 2A, but with more lobulated fibers, supports the idea that calpainopathy is a less active, but more chronic disease than dysferlinopathy. Unusual features indicated an extended limb-girdle muscular dystrophy disease spectrum. The use of acid phosphatase stain should be considered in suspected dysferlinopathies. To the best of our knowledge, this is the first report to define the relative proportions of the various forms of limb-girdle muscular dystrophy in China, based on protein testing.
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Affiliation(s)
- Omar Abdulmonem Mahmood
- Department of Neurology, Affiliated First Hospital of Jilin University, Changchun 130021, Jilin Province, China ; Department of Neuromedicine, Mosul Medical College, 41002, Mosul, Iraq
| | - Xinmei Jiang
- Department of Neurology, Affiliated First Hospital of Jilin University, Changchun 130021, Jilin Province, China
| | - Qi Zhang
- Department of Neurology, Affiliated First Hospital of Jilin University, Changchun 130021, Jilin Province, China
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Nilsson MI, Laureano ML, Saeed M, Tarnopolsky MA. Dysferlin aggregation in limb-girdle muscular dystrophy type 2B/myoshi myopathy necessitates mutational screen for diagnosis. Muscle Nerve 2013; 47:740-7. [PMID: 23519732 DOI: 10.1002/mus.23666] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/29/2012] [Indexed: 12/24/2022]
Affiliation(s)
- Mats I. Nilsson
- Department of Pediatrics and Medicine; Neuromuscular Clinic; McMaster University Hospital; 1200 Main Street West; Hamilton; Ontario L8N 3Z5; Canada
| | - Marissa L. Laureano
- Department of Pediatrics and Medicine; Neuromuscular Clinic; McMaster University Hospital; 1200 Main Street West; Hamilton; Ontario L8N 3Z5; Canada
| | - Munim Saeed
- Department of Pediatrics and Medicine; Neuromuscular Clinic; McMaster University Hospital; 1200 Main Street West; Hamilton; Ontario L8N 3Z5; Canada
| | - Mark A. Tarnopolsky
- Department of Pediatrics and Medicine; Neuromuscular Clinic; McMaster University Hospital; 1200 Main Street West; Hamilton; Ontario L8N 3Z5; Canada
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Zhao Z, Hu J, Sakiyama Y, Okamoto Y, Higuchi I, Li N, Shen H, Takashima H. DYSF mutation analysis in a group of Chinese patients with dysferlinopathy. Clin Neurol Neurosurg 2012; 115:1234-7. [PMID: 23254335 DOI: 10.1016/j.clineuro.2012.11.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2011] [Revised: 11/11/2012] [Accepted: 11/18/2012] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Dysferlinopathies belong to heterogeneous group of autosomal recessive muscular disorders caused by mutations in the gene encoding dysferlin. The classifications of the dysferlinopathies mainly include limb-girdle muscular dystrophy 2B (LGMD2B) with predominantly proximal weakness, Miyoshi myopathy (MM) with calf muscle weakness and atrophy, and distal myopathy with anterior tibial onset (DMAT) with tibialis muscle atrophy. We describe the genetic character of dysferlinopathies in a group of Chinese patients. METHODS DYSF mutations screening were done after muscle biopsy and immunohistochemical staining. RESULTS Eight patients showed an absence or drastic decrease of dysferlin expression in biopsied muscle. We identified 6 different mutations, including one nonsense mutation, two insertion mutation, two deletion mutations and one splice site mutation. Five of them were novel mutations. CONCLUSION We described 8 Chinese patients with dysferlinopathy (four had a distal phenotype of MM; one had a phenotype of DMAT and three presented with LGMD2B). It is the first report of genetic confirmed DMAT in China. Mutations c.3112C>T and c.1045dup, may be recurrent mutations in China.
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Affiliation(s)
- Zhe Zhao
- Department of Neuromuscular Disease, Third Hospital of Hebei Medical University, Shijiazhuang, PR China
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Azakir BA, Di Fulvio S, Kinter J, Sinnreich M. Proteasomal inhibition restores biological function of mis-sense mutated dysferlin in patient-derived muscle cells. J Biol Chem 2012; 287:10344-10354. [PMID: 22318734 DOI: 10.1074/jbc.m111.329078] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Dysferlin is a transmembrane protein implicated in surface membrane repair of muscle cells. Mutations in dysferlin cause the progressive muscular dystrophies Miyoshi myopathy, limb girdle muscular dystrophy 2B, and distal anterior compartment myopathy. Dysferlinopathies are inherited in an autosomal recessive manner, and many patients with this disease harbor mis-sense mutations in at least one of their two pathogenic DYSF alleles. These patients have significantly reduced or absent dysferlin levels in skeletal muscle, suggesting that dysferlin encoded by mis-sense alleles is rapidly degraded by the cellular quality control system. We reasoned that mis-sense mutated dysferlin, if salvaged from degradation, might be biologically functional. We used a dysferlin-deficient human myoblast culture harboring the common R555W mis-sense allele and a DYSF-null allele, as well as control human myoblast cultures harboring either two wild-type or two null alleles. We measured dysferlin protein and mRNA levels, resealing kinetics of laser-induced plasmalemmal wounds, myotube formation, and cellular viability after treatment of the human myoblast cultures with the proteasome inhibitors lactacystin or bortezomib (Velcade). We show that endogenous R555W mis-sense mutated dysferlin is degraded by the proteasomal system. Inhibition of the proteasome by lactacystin or Velcade increases the levels of R555W mis-sense mutated dysferlin. This salvaged protein is functional as it restores plasma membrane resealing in patient-derived myoblasts and reverses their deficit in myotube formation. Bortezomib and lactacystin did not cause cellular toxicity at the regimen used. Our results raise the possibility that inhibition of the degradation pathway of mis-sense mutated dysferlin could be used as a therapeutic strategy for patients harboring certain dysferlin mis-sense mutations.
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Affiliation(s)
- Bilal A Azakir
- Neuromuscular Research Group, Departments of Neurology and Biomedicine, University Hospital and University of Basel, 4031 Basel, Switzerland
| | - Sabrina Di Fulvio
- Neuromuscular Research Group, Departments of Neurology and Biomedicine, University Hospital and University of Basel, 4031 Basel, Switzerland
| | - Jochen Kinter
- Neuromuscular Research Group, Departments of Neurology and Biomedicine, University Hospital and University of Basel, 4031 Basel, Switzerland
| | - Michael Sinnreich
- Neuromuscular Research Group, Departments of Neurology and Biomedicine, University Hospital and University of Basel, 4031 Basel, Switzerland.
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Cacciottolo M, Numitone G, Aurino S, Caserta IR, Fanin M, Politano L, Minetti C, Ricci E, Piluso G, Angelini C, Nigro V. Muscular dystrophy with marked Dysferlin deficiency is consistently caused by primary dysferlin gene mutations. Eur J Hum Genet 2011; 19:974-80. [PMID: 21522182 PMCID: PMC3179367 DOI: 10.1038/ejhg.2011.70] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2010] [Revised: 02/15/2011] [Accepted: 02/16/2011] [Indexed: 11/09/2022] Open
Abstract
Dysferlin is a 237-kDa transmembrane protein involved in calcium-mediated sarcolemma resealing. Dysferlin gene mutations cause limb-girdle muscular dystrophy (LGMD) 2B, Miyoshi myopathy (MM) and distal myopathy of the anterior tibialis. Considering that a secondary Dysferlin reduction has also been described in other myopathies, our original goal was to identify cases with a Dysferlin deficiency without dysferlin gene mutations. The dysferlin gene is huge, composed of 55 exons that span 233 140 bp of genomic DNA. We performed a thorough mutation analysis in 65 LGMD/MM patients with ≤20% Dysferlin. The screening was exhaustive, as we sequenced both genomic DNA and cDNA. When required, we used other methods, including real-time PCR, long PCR and array CGH. In all patients, we were able to recognize the primary involvement of the dysferlin gene. We identified 38 novel mutation types. Some of these, such as a dysferlin gene duplication, could have been missed by conventional screening strategies. Nonsense-mediated mRNA decay was evident in six cases, in three of which both alleles were only detectable in the genomic DNA but not in the mRNA. Among a wide spectrum of novel gene defects, we found the first example of a 'nonstop' mutation causing a dysferlinopathy. This study presents the first direct and conclusive evidence that an amount of Dysferlin ≤20% is pathogenic and always caused by primary dysferlin gene mutations. This demonstrates the high specificity of a marked reduction of Dysferlin on western blot and the value of a comprehensive molecular approach for LGMD2B/MM diagnosis.
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Affiliation(s)
| | | | - Stefania Aurino
- TIGEM (Telethon Institute of Genetics and Medicine), Napoli, Italy
| | | | - Marina Fanin
- Department of Neurosciences, University of Padua, Padova, Italy
| | - Luisa Politano
- CIRM and Cardiomyology and Genetics Section, Dipartimento di Medicina Sperimentale, Seconda Università degli Studi di Napoli, Napoli, Italy
| | - Carlo Minetti
- Muscular and Neurodegenerative Disease Unit, G. Gaslini Institute, University of Genoa, Genova, Italy
| | - Enzo Ricci
- Department of Neurosciences, Università Cattolica Policlinico A. Gemelli, Rome, Italy
| | - Giulio Piluso
- CIRM and Dipartimento di Patologia Generale, Seconda Università degli Studi di Napoli, Napoli, Italy
| | | | - Vincenzo Nigro
- TIGEM (Telethon Institute of Genetics and Medicine), Napoli, Italy
- CIRM and Dipartimento di Patologia Generale, Seconda Università degli Studi di Napoli, Napoli, Italy
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