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Ramdas S, Beeson D, Dong YY. Congenital myasthenic syndromes: increasingly complex. Curr Opin Neurol 2024; 37:493-501. [PMID: 39051439 PMCID: PMC11377046 DOI: 10.1097/wco.0000000000001300] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/27/2024]
Abstract
PURPOSE OF REVIEW Congenital myasthenia syndromes (CMS) are treatable, inherited disorders affecting neuromuscular transmission. We highlight that the involvement of an increasing number of proteins is making the understanding of the disease mechanisms and potential treatments progressively more complex. RECENT FINDINGS Although early studies identified mutations of proteins directly involved in synaptic transmission at the neuromuscular junction, recently, next-generation sequencing has facilitated the identification of many novel mutations in genes that encode proteins that have a far wider expression profile, some even ubiquitously expressed, but whose defective function leads to impaired neuromuscular transmission. Unsurprisingly, mutations in these genes often causes a wider phenotypic disease spectrum where defective neuromuscular transmission forms only one component. This has implications for the management of CMS patients. SUMMARY Given the widening nonneuromuscular junction phenotypes in the newly identified forms of CMS, new therapies need to include disease-modifying approaches that address not only neuromuscular weakness but also the multisystem involvement. Whilst the current treatments for CMS are highly effective for many subtypes there remains, in a proportion of CMS patients, an unmet need for more efficacious therapies.
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Affiliation(s)
- Sithara Ramdas
- MDUK Neuromuscular Centre, Department of Paediatrics, University of Oxford
- Department of Paediatric Neurology, John Radcliffe Hospital
| | - David Beeson
- Neurosciences Group, Weatherall Institute of Molecular Medicine, The John Radcliffe, Oxford OX3 9DS
| | - Yin Yao Dong
- Neurosciences Group, Weatherall Institute of Molecular Medicine, The John Radcliffe, Oxford OX3 9DS
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2
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El-Wahsh S, Fraser C, Vucic S, Reddel S. Neuromuscular junction disorders: mimics and chameleons. Pract Neurol 2024:pn-2024-004148. [PMID: 39174301 DOI: 10.1136/pn-2024-004148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/07/2024] [Indexed: 08/24/2024]
Abstract
Neuromuscular junction (NMJ) disorders represent a heterogenous group of acquired and congenital disorders that present in variable and distinctive ways. The diagnosis is typically reached through a combination of clinical, serological, pharmacological and electrophysiological evaluation. While the diagnosis can be fairly straightforward in some cases, the overlap with other neurological disorders can make diagnosis challenging, particularly in pure ocular presentations and in seronegative patients. The over-reliance on serological tests and electrophysiological evaluation in isolation can lead to misdiagnosis. In this article, we provide an overview of the NMJ disorders, discuss red flags for the key differential diagnoses (mimics) and report the atypical ways in which NMJ disorders may present (chameleons).
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Affiliation(s)
- Shadi El-Wahsh
- Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
- Neurology Department, Concord Hospital, Concord, New South Wales, Australia
| | - Clare Fraser
- Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
- Save Sight Institute, The University of Sydney, Sydney, New South Wales, Australia
| | - Steve Vucic
- Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
- Neurology Department, Concord Hospital, Concord, New South Wales, Australia
| | - Stephen Reddel
- Neurology Department, Concord Hospital, Concord, New South Wales, Australia
- Brain and Mind Centre, The University of Sydney, Camperdown, New South Wales, Australia
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3
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Banerjee A, Datta Kanjilal S, Biswas T, Ghoshal A, Sarkar S. Congenital myasthenic syndrome: a tale of two siblings. Int J Neurosci 2024; 134:253-255. [PMID: 36018836 DOI: 10.1080/00207454.2022.2100774] [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: 03/15/2022] [Revised: 06/29/2022] [Accepted: 06/30/2022] [Indexed: 10/15/2022]
Abstract
Congenital myasthenic syndromes are a group of rare neuromuscular junction disorders. Traditional anticholinesterase inhibitors may not help in congenital myasthenic syndromes and in some variants may actually cause deterioration of symptoms. In this report, we describe a rare case of congenital myasthenic syndrome with heterozygous mutations in CHRNE gene (c.128A > T; heterozygous; exon 11) and COLQ gene (c.1201T > A; heterozygous; exon 16), which did not show improvement on neostigmine test but responded to treatment with oral salbutamol.
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Affiliation(s)
- Ahitagni Banerjee
- Department of Pediatrics, Institute of Post Graduate Medical Education and Research, Kolkata, India
| | - Sumana Datta Kanjilal
- Department of Pediatrics, Institute of Post Graduate Medical Education and Research, Kolkata, India
| | - Tamoghna Biswas
- Department of Pediatrics, Institute of Post Graduate Medical Education and Research, Kolkata, India
| | - Arnab Ghoshal
- Department of Pediatrics, Institute of Post Graduate Medical Education and Research, Kolkata, India
| | - Sumit Sarkar
- Department of Pediatrics, Institute of Post Graduate Medical Education and Research, Kolkata, India
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4
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Kediha MI, Tazir M, Sternberg D, Eymard B, Ali Pacha L. Innovative Therapeutic Approaches in Congenital Myasthenic Syndromes. Neurol Clin Pract 2024; 14:e200277. [PMID: 38737513 PMCID: PMC11081764 DOI: 10.1212/cpj.0000000000200277] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Accepted: 01/10/2024] [Indexed: 05/14/2024]
Abstract
Background and Objectives To provide real-word clinical follow-up data on patients carrying variations of congenital myasthenic syndromes (CMS) and who respond to some innovative drugs. Methods Patients recruited from the Neurology Department of the Mustapha Bacha university hospital in Algiers. Treated with innovative drugs, they were monitored and their clinical progress was evaluated on the basis of clinical arguments suggestive of CMSs, but also para clinical arguments (electromyography and genetic study). Results Six patients carrying different mutations in different genes of CMSs were studied. They had different pathophysiologic profiles (slow or fast channel syndromes, low expressor of receptor). Their therapeutic management was based on innovative drugs, normally indicated in other, non-neurological pathologies. Their outcome was toward a clear clinical improvement. Discussion This work relates the interest of proposing treatments (outside of Pyridostigmine) in the management of CMSs. These therapies can greatly modify the prognosis of patients suffering from this orphan disease. Classification of Evidence This study provides Class IV evidence that for patients with congenital myasthenic syndromes, some innovative treatments are effective.
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Affiliation(s)
- Mohamed I Kediha
- Neurology Department (MIK, MT, LAP), Mustapha Bacha University Hospital Algiers, Algeria; Myology Department (DS), Pitié Salpetriere, Paris; and Functional Unit for Neuromuscular Pathology (BE), Pitié Salpetriere, France
| | - Meriem Tazir
- Neurology Department (MIK, MT, LAP), Mustapha Bacha University Hospital Algiers, Algeria; Myology Department (DS), Pitié Salpetriere, Paris; and Functional Unit for Neuromuscular Pathology (BE), Pitié Salpetriere, France
| | - Damien Sternberg
- Neurology Department (MIK, MT, LAP), Mustapha Bacha University Hospital Algiers, Algeria; Myology Department (DS), Pitié Salpetriere, Paris; and Functional Unit for Neuromuscular Pathology (BE), Pitié Salpetriere, France
| | - Bruno Eymard
- Neurology Department (MIK, MT, LAP), Mustapha Bacha University Hospital Algiers, Algeria; Myology Department (DS), Pitié Salpetriere, Paris; and Functional Unit for Neuromuscular Pathology (BE), Pitié Salpetriere, France
| | - Lamia Ali Pacha
- Neurology Department (MIK, MT, LAP), Mustapha Bacha University Hospital Algiers, Algeria; Myology Department (DS), Pitié Salpetriere, Paris; and Functional Unit for Neuromuscular Pathology (BE), Pitié Salpetriere, France
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5
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Mackels L, Servais L. The Importance of Early Treatment of Inherited Neuromuscular Conditions. J Neuromuscul Dis 2024; 11:253-274. [PMID: 38306060 DOI: 10.3233/jnd-230189] [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] [Indexed: 02/03/2024]
Abstract
There has been tremendous progress in treatment of neuromuscular diseases over the last 20 years, which has transformed the natural history of these severely debilitating conditions. Although the factors that determine the response to therapy are many and in some instance remain to be fully elucidated, early treatment clearly has a major impact on patient outcomes across a number of inherited neuromuscular conditions. To improve patient care and outcomes, clinicians should be aware of neuromuscular conditions that require prompt treatment initiation. This review describes data that underscore the importance of early treatment of children with inherited neuromuscular conditions with an emphasis on data resulting from newborn screening efforts.
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Affiliation(s)
- Laurane Mackels
- MDUK Oxford Neuromuscular Centre, Department of Paediatrics, University of Oxford, Oxford, United Kingdom
- Adult Neurology Department, Citadelle Hospital, Liège, Belgium
| | - Laurent Servais
- Neuromuscular Centre, Division of Paediatrics, University and University Hospital of Liège, Liège, Belgium
- MDUK Oxford Neuromuscular Centre, Department of Paediatrics, University of Oxford & NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
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6
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Poulos J, Samuels M, Palace J, Beeson D, Robb S, Ramdas S, Chan S, Munot P. Congenital myasthenic syndromes: a retrospective natural history study of respiratory outcomes in a single centre. Brain Commun 2023; 5:fcad299. [PMID: 38035366 PMCID: PMC10684295 DOI: 10.1093/braincomms/fcad299] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 06/05/2023] [Accepted: 11/08/2023] [Indexed: 12/02/2023] Open
Abstract
Respiratory problems are a major cause of morbidity and mortality in patients with congenital myasthenic syndromes, a rare heterogeneous group of neuromuscular disorders caused by genetic defects impacting the structure and function of the neuromuscular junction. Recurrent, life-threatening episodic apnoea in early infancy and childhood and progressive respiratory failure requiring ventilation are features of certain genotypes of congenital myasthenic syndromes. Robb et al. published empirical guidance on respiratory management of the congenital myasthenic syndromes, but other than this workshop report, there are little published longitudinal natural history data on respiratory outcomes of these disorders. We report a retrospective, single-centre study on respiratory outcomes in a cohort of 40 well characterized genetically confirmed cases of congenital myasthenic syndromes, including 10 distinct subtypes (DOK7, COLQ, RAPSN, CHAT, CHRNA1, CHRNG, COL13A1, CHRNE, CHRNE fast channel syndrome and CHRNA1 slow channel syndrome), with many followed up over 20 years in our centre. A quantitative and longitudinal analysis of key spirometry and sleep study parameters, as well as a description of historical hospital admissions for respiratory decompensation, provides a snapshot of the respiratory trajectory of congenital myasthenic syndrome patients based on genotype.
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Affiliation(s)
- Jordan Poulos
- Paediatrics, University College London Medical School, London WC1E 6BT, UK
| | - Martin Samuels
- Respiratory Medicine, Great Ormond Street Hospital, London WC1N 3JH, UK
| | - Jacqueline Palace
- University of Oxford and Department of Neurology, Oxford Radcliffe Hospitals, Oxford OX3 9DU, UK
| | - David Beeson
- Neurology, Nuffield Department of Clinical Neurosciences, Oxford OX3 7BN, UK
| | - Stephanie Robb
- Dubowitz Neuromuscular Centre, Great Ormond Street Hospital, London WC1N 3JH, UK
| | - Sithara Ramdas
- Neurology, MDUK Neuromuscular Centre, Oxford University Hospitals, Oxford OX3 9DU, UK
| | - Samantha Chan
- Dubowitz Neuromuscular Centre, Great Ormond Street Hospital, London WC1N 3JH, UK
- Neurosciences, University College London and Institute of Child Health, London WC1N 1EH, UK
| | - Pinki Munot
- Dubowitz Neuromuscular Centre, Great Ormond Street Hospital, London WC1N 3JH, UK
- Neurosciences, University College London and Institute of Child Health, London WC1N 1EH, UK
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7
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Islam Kediha M, Tazir M, Sternberg D, Eymard B, Ali Pacha L. [Congenital myasthenic syndromes with kinetic abnormalities of the acetylcholine receptor]. Med Sci (Paris) 2023; 39 Hors série n° 1:58-63. [PMID: 37975772 DOI: 10.1051/medsci/2023135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2023] Open
Abstract
Congenital myasthenic syndromes (CMS) are genetically and phenotypically very heterogeneous conditions resulting in a defect in the neuromuscular transmission. Post-synaptic forms are the most frequent CMSs, and acetyl choline receptor (low expressor) deficiency is the most commonly involved pathophysiological mechanism. CMS with kinetic abnormalities of the acetylcholine receptor (AChr) are much rarer and can give rise to potentially life-threatening phenotypes. Among them, two types have been described: the slow channel syndrome (SCS) and the fast channel syndrome (FCS). Diagnosis and therapeutic management of such entities are specific to each type. In this work, we will illustrate the phenotypic aspects of CMS with kinetic abnormalities of the AChR by a narrative review of three Algerian families.
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Affiliation(s)
- Mohamed Islam Kediha
- Service de Neurologie, CHU Mustapha Bacha, Place 1er mai, 16000 Alger, Algérie. Université Benyoucef Benkhedda, Alger 1
| | - Meriem Tazir
- Service de Neurologie, CHU Mustapha Bacha, Place 1er mai, 16000 Alger, Algérie. Université Benyoucef Benkhedda, Alger 1
| | - Damien Sternberg
- Myogenetics unit, Département de biochimie métabolique, Hôpital universitaire Pitié-Salpêtrière, 75651 Paris Cedex 13, France
| | | | - Lamia Ali Pacha
- Service de Neurologie, CHU Mustapha Bacha, Place 1er mai, 16000 Alger, Algérie. Université Benyoucef Benkhedda, Alger 1
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8
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Ohno K, Ohkawara B, Shen XM, Selcen D, Engel AG. Clinical and Pathologic Features of Congenital Myasthenic Syndromes Caused by 35 Genes-A Comprehensive Review. Int J Mol Sci 2023; 24:ijms24043730. [PMID: 36835142 PMCID: PMC9961056 DOI: 10.3390/ijms24043730] [Citation(s) in RCA: 34] [Impact Index Per Article: 34.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2023] [Revised: 02/09/2023] [Accepted: 02/09/2023] [Indexed: 02/16/2023] Open
Abstract
Congenital myasthenic syndromes (CMS) are a heterogeneous group of disorders characterized by impaired neuromuscular signal transmission due to germline pathogenic variants in genes expressed at the neuromuscular junction (NMJ). A total of 35 genes have been reported in CMS (AGRN, ALG14, ALG2, CHAT, CHD8, CHRNA1, CHRNB1, CHRND, CHRNE, CHRNG, COL13A1, COLQ, DOK7, DPAGT1, GFPT1, GMPPB, LAMA5, LAMB2, LRP4, MUSK, MYO9A, PLEC, PREPL, PURA, RAPSN, RPH3A, SCN4A, SLC18A3, SLC25A1, SLC5A7, SNAP25, SYT2, TOR1AIP1, UNC13A, VAMP1). The 35 genes can be classified into 14 groups according to the pathomechanical, clinical, and therapeutic features of CMS patients. Measurement of compound muscle action potentials elicited by repetitive nerve stimulation is required to diagnose CMS. Clinical and electrophysiological features are not sufficient to identify a defective molecule, and genetic studies are always required for accurate diagnosis. From a pharmacological point of view, cholinesterase inhibitors are effective in most groups of CMS, but are contraindicated in some groups of CMS. Similarly, ephedrine, salbutamol (albuterol), amifampridine are effective in most but not all groups of CMS. This review extensively covers pathomechanical and clinical features of CMS by citing 442 relevant articles.
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Affiliation(s)
- Kinji Ohno
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
- Correspondence: (K.O.); (A.G.E.)
| | - Bisei Ohkawara
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Xin-Ming Shen
- Department of Neurology and Neuromuscular Research Laboratory, Mayo Clinic, Rochester, MN 55905, USA
| | - Duygu Selcen
- Department of Neurology and Neuromuscular Research Laboratory, Mayo Clinic, Rochester, MN 55905, USA
| | - Andrew G. Engel
- Department of Neurology and Neuromuscular Research Laboratory, Mayo Clinic, Rochester, MN 55905, USA
- Correspondence: (K.O.); (A.G.E.)
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Öztürk S, Güleç A, Erdoğan M, Demir M, Canpolat M, Gümüş H, Çağlayan AO, Dündar M, Per H. Congenital Myasthenic Syndromes in Turkey: Clinical and Molecular Characterization of 16 Cases With Three Novel Mutations. Pediatr Neurol 2022; 136:43-49. [PMID: 36099689 DOI: 10.1016/j.pediatrneurol.2022.08.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Revised: 07/23/2022] [Accepted: 08/09/2022] [Indexed: 11/25/2022]
Abstract
BACKGROUND Congenital myasthenic syndromes (CMS) are composed of numerous hereditary disorders involving genetic mutations in proteins essential to the integrity of neuromuscular transmission. The symptoms of CMS vary according to the age at onset of symptoms, and the type and severity of muscle weakness. Effective treatment and genetic counseling depend upon the underlying pathogenic molecular mechanism and subtype of CMS. METHODS A retrospective and cross-sectional study was performed with 16 patients with a genetically confirmed diagnosis of CMS to share our experience with clinical symptoms, demographic data, genetic variants, and treatments applied. RESULTS Sixteen patients with a specific CMS genetic diagnosis (three novel mutations) were identified, including CHRNE (n = 7), DOK7 (n = 2), AGRN (n = 2), RAPSN (n = 1), CHRNA1 (n = 1), CHRNB1 (n = 1), CHAT (n = 1), and SCN4A (n = 1). Age at onset of symptoms ranged from the neonatal period to 12 years. Genetic diagnosis was confirmed between the ages of three months and 17 years. A significant delay was determined between the onset of symptoms and genetic diagnosis of the disease. CONCLUSIONS This study highlights the importance of genetic testing in CMS. Due to the rarity of CMS, more cases will be recognized and reported as the use of laboratory and genetic testing accelerates. We hope that our experience will grow and contribute further to the literature as clinical follow-up and treatment increase.
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Affiliation(s)
- Selcan Öztürk
- Fellow in Pediatric Neurology, Faculty of Medicine, Division of Pediatric Neurology, Department of Pediatrics, Erciyes University, Kayseri, Turkey
| | - Ayten Güleç
- Fellow in Pediatric Neurology, Faculty of Medicine, Division of Pediatric Neurology, Department of Pediatrics, Erciyes University, Kayseri, Turkey
| | - Murat Erdoğan
- Medical Doctor, Department of Medical Genetics, Kayseri State Hospital, Kayseri, Turkey
| | - Mikail Demir
- Medical Doctor, Faculty of Medicine, Department of Medical Genetics, Erciyes University, Kayseri, Turkey
| | - Mehmet Canpolat
- Professor of Pediatrics, Faculty of Medicine, Division of Pediatric Neurology, Department of Pediatrics, Erciyes University, Kayseri, Turkey
| | - Hakan Gümüş
- Professor of Pediatrics, Faculty of Medicine, Division of Pediatric Neurology, Department of Pediatrics, Erciyes University, Kayseri, Turkey
| | - Ahmet Okay Çağlayan
- Professor of Genetics, Faculty of Medicine, Department of Genetics, Dokuz Eylül University, Izmir, Turkey
| | - Munis Dündar
- Professor of Genetics, Faculty of Medicine, Department of Genetics, Erciyes University, Kayseri, Turkey
| | - Hüseyin Per
- Professor of Pediatrics, Faculty of Medicine, Division of Pediatric Neurology, Department of Pediatrics, Erciyes University, Kayseri, Turkey.
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10
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Boon HTM, Jacobs B, Wouter VR, Kamsteeg EJ, Kuks JBM, Vincent A, Eymard B, Voermans NC. Slow Channel Syndrome Revisited: 40 Years Clinical Follow-Up and Genetic Characterization of Two Cases. J Neuromuscul Dis 2022; 9:525-532. [PMID: 35466948 DOI: 10.3233/jnd-220798] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND The slow channel syndrome is a rare hereditary disorder caused by a dominant gain-of-function variant in one of the subunits of the acetylcholine receptor at the neuromuscular junction. Patients typically experience axial, limb and particularly extensor finger muscle weakness. OBJECTIVE Age at diagnosis is variable and although the long-term prognosis is important for newly diagnosed patients, extensive follow-up studies are rare. We aim to provide answers and perspective for this patient group by presenting an elaborate description of the lifetime follow-up of two slow channel syndrome patients. METHODS We describe 40 years follow-up in two, genetically confirmed cases (CHRNA1; c.866G > T p.(Ser289Ile)(legacy Ser269Ile) and CHRNE; c.721C > T p.(Leu241Phe)(legacy Leu221Phe) variants). RESULTS We find that the disease course has a fluctuating pattern and is only mildly progressive. However, hormonal imbalances, (psychological) stress or excessive hot or cold environments are often aggravating factors. Quinidine and fluoxetine are helpful, but ephedrine and salbutamol may also improve symptoms. CONCLUSION Slow channel syndrome is mildly progressive with a fluctuating pattern. The observations reported here provide a lifespan perspective and answers to the most pressing questions about prognosis and treatment options for newly diagnosed patients.
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Affiliation(s)
- Helena T M Boon
- Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Bram Jacobs
- Department of Neurology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - van Rheenen Wouter
- Department of Neurology, University Medical Centre Utrecht, The Netherlands
| | - Erik-Jan Kamsteeg
- Department of Genetics, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Jan B M Kuks
- Department of Neurology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Angela Vincent
- Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, University of Oxford, UK
| | | | - Nicol C Voermans
- Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Centre, Nijmegen, The Netherlands
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11
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Dejthevaporn C, Wetchaphanphesat S, Pulkes T, Rattanasiri S, Engel AG, Witoonpanich R. Treatment of slow-channel congenital myasthenic syndrome in a Thai family with fluoxetine. J Clin Neurosci 2022; 96:85-89. [PMID: 34999496 DOI: 10.1016/j.jocn.2021.12.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Revised: 11/11/2021] [Accepted: 12/12/2021] [Indexed: 11/30/2022]
Abstract
The slow-channel congenital myasthenic syndrome is an autosomal dominant neuromuscular disorder caused by mutations in different subunits of the acetylcholine receptor. Fluoxetine, a common antidepressant and long-lived open-channel blocker of acetylcholine receptor, has been reported to be beneficial in the slow-channel congenital myasthenic syndrome. Here we report a prospective open label study of fluoxetine treatment in some affected members of a Thai family with slow-channel congenital myasthenic syndrome caused by a novel p.Gly153Ala (c.518G > C) mutation in CHRNA1 in the AChR α subunit. These patients showed significant clinical improvement following fluoxetine treatment but their respiratory function responded variably.
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Affiliation(s)
- Charungthai Dejthevaporn
- Division of Neurology, Department of Medicine, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
| | | | - Teeratorn Pulkes
- Division of Neurology, Department of Medicine, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
| | - Sasivimol Rattanasiri
- Clinical Epidemiology Unit, Research Center, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
| | - Andrew G Engel
- Department of Neurology and Muscle Research Laboratory, Mayo Clinic College of Medicine, Rochester, MN, USA
| | - Rawiphan Witoonpanich
- Division of Neurology, Department of Medicine, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand.
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12
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Treatment and Management of Disorders of the Neuromuscular Junction. Neuromuscul Disord 2022. [DOI: 10.1016/b978-0-323-71317-7.00019-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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13
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Rare slow channel congenital myasthenic syndromes without repetitive compound muscle action potential and dramatic response to low dose fluoxetine. Acta Neurol Belg 2021; 121:1755-1760. [PMID: 33030681 DOI: 10.1007/s13760-020-01505-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Accepted: 09/15/2020] [Indexed: 10/23/2022]
Abstract
Congenital myasthenic syndromes are rare hereditary disorders caused by mutations associated with proteins of the neuromuscular junction. Abnormal ''gain of function'' mutations result in prolonged nicotinic acetylcholine receptor channel open state causing a rare subtype of CMS, slow-channel CMS (SCCMS). Mutations in the delta subunit encoding the gene, CHRND, resulting in SCCMS are extremely rare. An important clue to the diagnosis of SCCMS is repetitive CMAP's. Fluoxetine, usually at high doses, is used to treat SCCMS. The mutation, recently described in one patient, was identified by whole exome sequencing and validated, and its segregation with the disease was ascertained by Sanger sequencing. Here, we describe clinical and genetic findings of an early onset SCCMS patient carrying a very rare missense mutation c.880C > T in CHRND causing a highly conserved leucine to phenylalanine substitution in the M2 domain of CHRND. The patient had no repetitive CMAP. He had a dramatic response to fluoxetine at low-moderate doses (40 mg/day), increasing over months: Being wheelchair bound, he could walk independently after treatment. Rare cases may offer insight into the pathological gating mechanism leading to CMS. SCCMS should be suspected even without a repetitive CMAP. Fluoxetine at relatively low doses can be a very effective treatment.
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14
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Ramdas S, Beeson D. Congenital myasthenic syndromes: where do we go from here? Neuromuscul Disord 2021; 31:943-954. [PMID: 34736634 DOI: 10.1016/j.nmd.2021.07.400] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 07/22/2021] [Accepted: 07/27/2021] [Indexed: 11/27/2022]
Abstract
Congenital myasthenia syndromes are rare but often treatable conditions affecting neuromuscular transmission. They result from loss or impaired function of one of a number of proteins secondary to a genetic defect. An estimate of the prevalence in the UK gave 9.2 cases per million, however, this is likely an underestimate since the adoption of next generation sequencing for diagnosis away from specialist centres is enhancing the 'pick up' rate. Next generation sequencing has helped identify a series of novel genes that harbour mutations causative for congenital myasthenic syndrome that include not only genes that encode proteins specifically expressed at the neuromuscular junction but also those that are ubiquitously expressed. The list of genes harbouring disease-causing mutations for congenital myasthenic syndrome continues to expand and is now over 30, but with many of the newly identified genes it is increasingly being recognised that abnormal neuromuscular transmission is only one component of a multifaceted phenotype in which muscle, the central nervous system, and other organs may also be affected. Treatment can be tailored to the underlying molecular mechanism for impaired neuromuscular transmission but treating the more complex multifaceted disorders and will require development of new therapies.
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Affiliation(s)
- Sithara Ramdas
- MDUK Neuromuscular centre, Children's Hospital, John Radcliffe Hospital, Oxford, OX3 9DU, UK
| | - David Beeson
- Neurosciences Group, Weatherall Institute of Molecular Medicine, The John Radcliffe, Oxford OX3 9DS, UK.
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15
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Arias HR, Targowska-Duda KM, García-Colunga J, Ortells MO. Is the Antidepressant Activity of Selective Serotonin Reuptake Inhibitors Mediated by Nicotinic Acetylcholine Receptors? Molecules 2021; 26:molecules26082149. [PMID: 33917953 PMCID: PMC8068400 DOI: 10.3390/molecules26082149] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Revised: 03/31/2021] [Accepted: 04/05/2021] [Indexed: 12/05/2022] Open
Abstract
It is generally assumed that selective serotonin reuptake inhibitors (SSRIs) induce antidepressant activity by inhibiting serotonin (5-HT) reuptake transporters, thus elevating synaptic 5-HT levels and, finally, ameliorates depression symptoms. New evidence indicates that SSRIs may also modulate other neurotransmitter systems by inhibiting neuronal nicotinic acetylcholine receptors (nAChRs), which are recognized as important in mood regulation. There is a clear and strong association between major depression and smoking, where depressed patients smoke twice as much as the normal population. However, SSRIs are not efficient for smoking cessation therapy. In patients with major depressive disorder, there is a lower availability of functional nAChRs, although their amount is not altered, which is possibly caused by higher endogenous ACh levels, which consequently induce nAChR desensitization. Other neurotransmitter systems have also emerged as possible targets for SSRIs. Studies on dorsal raphe nucleus serotoninergic neurons support the concept that SSRI-induced nAChR inhibition decreases the glutamatergic hyperstimulation observed in stress conditions, which compensates the excessive 5-HT overflow in these neurons and, consequently, ameliorates depression symptoms. At the molecular level, SSRIs inhibit different nAChR subtypes by noncompetitive mechanisms, including ion channel blockade and induction of receptor desensitization, whereas α9α10 nAChRs, which are peripherally expressed and not directly involved in depression, are inhibited by competitive mechanisms. According to the functional and structural results, SSRIs bind within the nAChR ion channel at high-affinity sites that are spread out between serine and valine rings. In conclusion, SSRI-induced inhibition of a variety of nAChRs expressed in different neurotransmitter systems widens the complexity by which these antidepressants may act clinically.
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Affiliation(s)
- Hugo R. Arias
- Department of Pharmacology and Physiology, Oklahoma State University College of Osteopathic Medicine, Tahlequah, OK 74464, USA
- Correspondence: ; Tel.: +1-918-525-6324; Fax: +1-918-280-2515
| | | | - Jesús García-Colunga
- Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Campus Juriquilla, Universidad Nacional Autónoma de México, Querétaro 76230, Mexico;
| | - Marcelo O. Ortells
- Facultad de Medicina, Universidad de Morón, CONICET, Morón 1708, Argentina;
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16
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Zhao Y, Li Y, Bian Y, Yao S, Liu P, Yu M, Zhang W, Wang Z, Yuan Y. Congenital myasthenic syndrome in China: genetic and myopathological characterization. Ann Clin Transl Neurol 2021; 8:898-907. [PMID: 33756069 PMCID: PMC8045908 DOI: 10.1002/acn3.51346] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Revised: 03/01/2021] [Accepted: 03/02/2021] [Indexed: 11/05/2022] Open
Abstract
OBJECTIVE We aimed to summarize the clinical, genetic, and myopathological features of a cohort of Chinese patients with congenital myasthenic syndrome, and follow up on therapeutic outcomes. METHODS The clinical spectrum, mutational frequency of genes, and pathological diagnostic clues of various subtypes of patients with congenital myasthenic syndrome were summarized. Therapeutic effects were followed up. RESULTS Thirty-five patients from 29 families were recruited. Ten genes were identified: GFPT1 (27.6%), AGRN (17.2%), CHRNE (17.2%), COLQ (13.8%), GMPPB (6.9%), CHAT, CHRNA1, DOK7, COG7, and SLC25A1 (3.4% each, respectively). Sole limb-girdle weakness was found in patients with AGRN (1/8) and GFPT1 (7/8) mutations, whereas distal weakness was all observed in patients with AGRN (6/8) mutations. Tubular aggregates were only found in patients with GFPT1 mutations (5/6). The patients with GMPPB mutations (2/2) had decreased alpha-dystroglycan. Acetylcholinesterase inhibitor therapy resulted in no response or worsened symptoms in patients with COLQ mutations, a diverse response in patients with AGRN mutations, and a good response in patients with other subtypes. Albuterol therapy was effective or harmless in most subtypes. Therapy effects became attenuated with long-term use in patients with COLQ or AGRN mutations. INTERPRETATION The genetic distribution of congenital myasthenic syndrome in China is distinct from that of other ethnic origins. The appearance of distal weakness, selective limb-girdle myasthenic syndrome, tubular aggregates, and decreased alpha-dystroglycan were indicative of the specific subtypes. Based on the follow-up findings, we suggest cautious evaluation of the long-term efficacy of therapeutic agents in congenital myasthenic syndrome.
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Affiliation(s)
- Yawen Zhao
- Department of Neurology, Peking University First Hospital, Beijing, China
| | - Ying Li
- Department of Neurology, Capital Medical University Affiliated Anzhen Hospital, Chaoyang-qu, China
| | - Yang Bian
- Department of Neurology, Sixth Medical Center of PLA General Hospital, Beijing, China
| | - Sheng Yao
- Department of Neurology, Sixth Medical Center of PLA General Hospital, Beijing, China
| | - Penju Liu
- Department of Neurology, Capital Medical University Affiliated Anzhen Hospital, Chaoyang-qu, China
| | - Meng Yu
- Department of Neurology, Peking University First Hospital, Beijing, China
| | - Wei Zhang
- Department of Neurology, Peking University First Hospital, Beijing, China
| | - Zhaoxia Wang
- Department of Neurology, Peking University First Hospital, Beijing, China
| | - Yun Yuan
- Department of Neurology, Peking University First Hospital, Beijing, China
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17
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Laforgia N, De Cosmo L, Palumbo O, Ranieri C, Sesta M, Capodiferro D, Pantaleo A, Iapicca P, Lastella P, Capozza M, Schettini F, Bukvic N, Bagnulo R, Resta N. The First Case of Congenital Myasthenic Syndrome Caused by a Large Homozygous Deletion in the C-Terminal Region of COLQ (Collagen Like Tail Subunit of Asymmetric Acetylcholinesterase) Protein. Genes (Basel) 2020; 11:genes11121519. [PMID: 33353066 PMCID: PMC7765904 DOI: 10.3390/genes11121519] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 12/13/2020] [Accepted: 12/15/2020] [Indexed: 12/13/2022] Open
Abstract
Congenital myasthenic syndromes (CMSs) are caused by mutations in genes that encode proteins involved in the organization, maintenance, function, or modification of the neuromuscular junction. Among these, the collagenic tail of endplate acetylcholinesterase protein (COLQ; MIM 603033) has a crucial role in anchoring the enzyme into the synaptic basal lamina. Here, we report on the first case of a patient with a homozygous deletion affecting the last exons of the COLQ gene in a CMS patient born to consanguineous parents of Pakistani origin. Electromyography (EMG), electroencephalography (EEG), clinical exome sequencing (CES), and single nucleotide polymorphism (SNP) array analyses were performed. The subject was born at term after an uneventful pregnancy and developed significant hypotonia and dystonia, clinical pseudoseizures, and recurring respiratory insufficiency with a need for mechanical ventilation. CES analysis of the patient revealed a homozygous deletion of the COLQ gene located on the 3p25.1 chromosome region. The SNP-array confirmed the presence of deletion that extended from exon 11 to the last exon 17 with a size of 19.5 Kb. Our results add new insights about the underlying pathogenetic mechanisms expanding the spectrum of causative COLQ mutations. It is relevant, considering the therapeutic implications, to apply suitable molecular approaches so that no type of mutation is missed: “each lost mutation means a baby treated improperly”.
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Affiliation(s)
- Nicola Laforgia
- Section of Neonatology and Neonatal Intensive Care Unit, Department of Biomedical Science and Human Oncology (DIMO), University of Bari “Aldo Moro”, 70124 Bari, Italy; (N.L.); (L.D.C.); (D.C.); (M.C.); (F.S.)
| | - Lucrezia De Cosmo
- Section of Neonatology and Neonatal Intensive Care Unit, Department of Biomedical Science and Human Oncology (DIMO), University of Bari “Aldo Moro”, 70124 Bari, Italy; (N.L.); (L.D.C.); (D.C.); (M.C.); (F.S.)
| | - Orazio Palumbo
- Division of Medical Genetics, Fondazione IRCCS Casa Sollievo della Sofferenza, 71013 San Giovanni Rotondo, Italy;
| | - Carlotta Ranieri
- Division of Medical Genetics, Department of Biomedical Sciences and Human Oncology (DIMO), University of Bari “Aldo Moro”, 70124 Bari, Italy; (C.R.); (A.P.); (R.B.)
| | - Michela Sesta
- Neurology Unit, University Hospital Consortium Corporation Polyclinic of Bari, 70124 Bari, Italy;
| | - Donatella Capodiferro
- Section of Neonatology and Neonatal Intensive Care Unit, Department of Biomedical Science and Human Oncology (DIMO), University of Bari “Aldo Moro”, 70124 Bari, Italy; (N.L.); (L.D.C.); (D.C.); (M.C.); (F.S.)
| | - Antonino Pantaleo
- Division of Medical Genetics, Department of Biomedical Sciences and Human Oncology (DIMO), University of Bari “Aldo Moro”, 70124 Bari, Italy; (C.R.); (A.P.); (R.B.)
| | | | - Patrizia Lastella
- Rare Diseases Centre—Internal Medicine Unit “C. Frugoni”, Polyclinic of Bari, 70124 Bari, Italy;
| | - Manuela Capozza
- Section of Neonatology and Neonatal Intensive Care Unit, Department of Biomedical Science and Human Oncology (DIMO), University of Bari “Aldo Moro”, 70124 Bari, Italy; (N.L.); (L.D.C.); (D.C.); (M.C.); (F.S.)
| | - Federico Schettini
- Section of Neonatology and Neonatal Intensive Care Unit, Department of Biomedical Science and Human Oncology (DIMO), University of Bari “Aldo Moro”, 70124 Bari, Italy; (N.L.); (L.D.C.); (D.C.); (M.C.); (F.S.)
| | - Nenad Bukvic
- Medical Genetics Section, University Hospital Consortium Corporation Polyclinic of Bari, 70124 Bari, Italy;
| | - Rosanna Bagnulo
- Division of Medical Genetics, Department of Biomedical Sciences and Human Oncology (DIMO), University of Bari “Aldo Moro”, 70124 Bari, Italy; (C.R.); (A.P.); (R.B.)
| | - Nicoletta Resta
- Division of Medical Genetics, Department of Biomedical Sciences and Human Oncology (DIMO), University of Bari “Aldo Moro”, 70124 Bari, Italy; (C.R.); (A.P.); (R.B.)
- Medical Genetics Section, University Hospital Consortium Corporation Polyclinic of Bari, 70124 Bari, Italy;
- Correspondence: ; Tel.: +39-0805593619
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18
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Stephens BD, Kang MK. Pearls & Oy-sters: The Myasthenic Double Humps. Neurology 2020; 96:545-547. [PMID: 33277409 DOI: 10.1212/wnl.0000000000011287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Brian D Stephens
- From the Department of Neurology, University of California, San Francisco.
| | - Min K Kang
- From the Department of Neurology, University of California, San Francisco
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19
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Di L, Chen H, Lu Y, Selcen D, Engel AG, Da Y, Shen XM. Determinants of the repetitive-CMAP occurrence and therapy efficacy in slow-channel myasthenia. Neurology 2020; 95:e2781-e2793. [PMID: 32907971 DOI: 10.1212/wnl.0000000000010734] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2019] [Accepted: 06/22/2020] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVE To find determinants of the occurrence of repetitive compound muscle action potential (R-CMAP) and to assess the efficacy of channel blocker therapy in slow-channel congenital myasthenic syndrome (SCCMS). METHODS Neurologic examination, EMG study, laboratory test, muscle biopsy, and next-generation and Sanger sequencing; literature review of reported patients with SCCMS, including EMG, kinetics of mutant acetylcholine receptors (AChRs), and response to therapy; and simulation of the decay phase of endplate potential (EPP) were performed. RESULTS Three newly characterized and 57 reported patients with SCCMS with mutations of AChR subunits were included. In patients with R-CMAP, the length of channel opening bursts of mutant AChR was increased 8.68 ± 2.82 (mean ± SD)-fold compared to wild-type; in patients without R-CMAP, the length was increased 3.84 ± 0.65-fold (95% confidence interval 3.18-6.50, p = 0.000014). The EPP amplitude after refractory period of action potential in muscle fiber is above the threshold in patients with R-CMAP but below the threshold in patients without R-CMAP. In patients with good results from channel blocker therapy, treatment was initiated 11.60 ± 5.17 years after onset of symptoms; in patients with no to moderate benefit from channel blocker therapy, treatment was initiated 30.70 ± 12.72 years after onset (95% confidence interval -28.57 to -9.63, p = 0.00089). CONCLUSIONS In SCCMS, the R-CMAP occurrence is related to the extent of prolongation of the opening episodes of mutant AChR channel. Channel blocker treatment is more effective the sooner it is started after the onset of symptoms. CLASSIFICATION OF EVIDENCE This study provides Class IV evidence that channel blocker therapy in patients with SCCMS improves symptoms.
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Affiliation(s)
- Li Di
- From the Department of Neurology (L.D., H.C., Y.L., Y.D.), Xuanwu Hospital, Capital Medical University, Beijing, China; and Department of Neurology and Neuromuscular Research Laboratory (L.D., D.S., A.G.E., X.-M.S.), Mayo Clinic, Rochester, MN
| | - Hai Chen
- From the Department of Neurology (L.D., H.C., Y.L., Y.D.), Xuanwu Hospital, Capital Medical University, Beijing, China; and Department of Neurology and Neuromuscular Research Laboratory (L.D., D.S., A.G.E., X.-M.S.), Mayo Clinic, Rochester, MN
| | - Yan Lu
- From the Department of Neurology (L.D., H.C., Y.L., Y.D.), Xuanwu Hospital, Capital Medical University, Beijing, China; and Department of Neurology and Neuromuscular Research Laboratory (L.D., D.S., A.G.E., X.-M.S.), Mayo Clinic, Rochester, MN
| | - Duygu Selcen
- From the Department of Neurology (L.D., H.C., Y.L., Y.D.), Xuanwu Hospital, Capital Medical University, Beijing, China; and Department of Neurology and Neuromuscular Research Laboratory (L.D., D.S., A.G.E., X.-M.S.), Mayo Clinic, Rochester, MN
| | - Andrew G Engel
- From the Department of Neurology (L.D., H.C., Y.L., Y.D.), Xuanwu Hospital, Capital Medical University, Beijing, China; and Department of Neurology and Neuromuscular Research Laboratory (L.D., D.S., A.G.E., X.-M.S.), Mayo Clinic, Rochester, MN
| | - Yuwei Da
- From the Department of Neurology (L.D., H.C., Y.L., Y.D.), Xuanwu Hospital, Capital Medical University, Beijing, China; and Department of Neurology and Neuromuscular Research Laboratory (L.D., D.S., A.G.E., X.-M.S.), Mayo Clinic, Rochester, MN.
| | - Xin-Ming Shen
- From the Department of Neurology (L.D., H.C., Y.L., Y.D.), Xuanwu Hospital, Capital Medical University, Beijing, China; and Department of Neurology and Neuromuscular Research Laboratory (L.D., D.S., A.G.E., X.-M.S.), Mayo Clinic, Rochester, MN.
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20
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Shen Y, Wang B, Zheng X, Zhang W, Wu H, Hei M. A Neonate With MuSK Congenital Myasthenic Syndrome Presenting With Refractory Respiratory Failure. Front Pediatr 2020; 8:166. [PMID: 32373561 PMCID: PMC7176811 DOI: 10.3389/fped.2020.00166] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/29/2019] [Accepted: 03/24/2020] [Indexed: 12/04/2022] Open
Abstract
This was a Chinese neonatal congenital myasthenic syndromes case caused by muscle skeletal receptor tyrosine kinase gene mutations, which have not been recorded in the Human Gene Mutation Database. The newborn girl had refractory respiratory failure from birth to death, and failed extubation seven times. She had two heterozygous mutations: a non-sense mutation c.2062C>T (p.Q688X) inherited from father and a missense mutation c.2324T>C (p.F775S) inherited from mother, which was predicted pathogenic and harmful by bioinformatic softwares SIFT, PolyPhen_2 and REVEL. She positively responded to Neostigmine, but her parent quitted treatment when Pyridostigmine Bromide (2 mg/kg Q12 h) had been given for 8 days. She died 2 days after she was taken home by her parents on age of 56 days.
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Affiliation(s)
- Yanhua Shen
- Neonatal Center, Beijing Children's Hospital, Capital Medical University, Beijing, China
- National Center for Children's Health, Beijing, China
| | - Bo Wang
- Neonatal Center, Beijing Children's Hospital, Capital Medical University, Beijing, China
- National Center for Children's Health, Beijing, China
| | - Xia Zheng
- Neonatal Center, Beijing Children's Hospital, Capital Medical University, Beijing, China
- National Center for Children's Health, Beijing, China
| | - Wenwen Zhang
- Neonatal Center, Beijing Children's Hospital, Capital Medical University, Beijing, China
- National Center for Children's Health, Beijing, China
| | - Hailan Wu
- Neonatal Center, Beijing Children's Hospital, Capital Medical University, Beijing, China
- National Center for Children's Health, Beijing, China
| | - Mingyan Hei
- Neonatal Center, Beijing Children's Hospital, Capital Medical University, Beijing, China
- National Center for Children's Health, Beijing, China
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21
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Nakamura H, Komiya H, Uematsu E, Nakae Y, Tanaka K, Kunii M, Tada M, Joki H, Koyano S, Matsumoto N, Doi H, Takeuchi H, Tanaka F. Adult-onset vocal cord paralysis in slow-channel congenital myasthenic syndrome. Neurol Clin Pract 2019; 9:e45-e47. [DOI: 10.1212/cpj.0000000000000599] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2018] [Accepted: 11/17/2018] [Indexed: 11/15/2022]
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22
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Shen XM, Milone M, Wang HL, Banwell B, Selcen D, Sine SM, Engel AG. Slow-channel myasthenia due to novel mutation in M2 domain of AChR delta subunit. Ann Clin Transl Neurol 2019; 6:2066-2078. [PMID: 31560172 PMCID: PMC6801167 DOI: 10.1002/acn3.50902] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Accepted: 09/01/2019] [Indexed: 11/09/2022] Open
Abstract
OBJECTIVE To characterize the molecular and phenotypic basis of a severe slow-channel congenital myasthenic syndrome (SCCMS). METHODS Intracellular and single-channel recordings from patient endplates; alpha-bungarotoxin binding studies; direct sequencing of AChR genes; microsatellite analysis; kinetic analysis of AChR activation; homology modeling of adult human AChR structure. RESULTS Among 24 variants reported to cause SCCMS only two appear in the AChR δ-subunit. We here report a 16-year-old patient harboring a novel δL273F mutation (δL294F in HGVS nomenclature) in the second transmembrane domain (M2) of the AChR δ subunit. Kinetic analyses with ACh and the weak agonist choline indicate that δL273F prolongs the channel opening bursts 9.4-fold due to a 75-fold increase in channel gating efficiency, whereas a previously identified εL269F mutation (εL289F in HGVS nomenclature) at an equivalent location in the AChR ε-subunit prolongs channel opening bursts 4.4-fold due to a 30-fold increase in gating efficiency. Structural modeling of AChR predicts that inter-helical hydrophobic interactions between the mutant residue in the δ and ε subunit and nearby M2 domain residues in neighboring α subunits contribute to structural stability of the open relative to the closed channel states. INTERPRETATION The greater increase in gating efficiency by δL273F than by εL269F explains why δL273F has more severe clinical effects. Both δL273F and εL269F impair channel gating by disrupting hydrophobic interactions with neighboring α-subunits. Differences in the extent of impairment of channel gating in δ and ε mutant receptors suggest unequal contributions of ε/α and δ/α subunit pairs to gating efficiency.
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Affiliation(s)
- Xin-Ming Shen
- Department of Neurology and Neuromuscular Research Laboratory, Mayo Clinic, Rochester, Minnesota
| | - Margherita Milone
- Department of Neurology and Neuromuscular Research Laboratory, Mayo Clinic, Rochester, Minnesota
| | - Hang-Long Wang
- Department of Neurology and Vesicular Biology Laboratory, Mayo Clinic, Rochester, Minnesota
| | - Brenda Banwell
- Division of Neurology, Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
| | - Duygu Selcen
- Department of Neurology and Neuromuscular Research Laboratory, Mayo Clinic, Rochester, Minnesota
| | - Steven M Sine
- Department of Physiology and Biomedical Engineering and Receptor Biology Laboratory, Mayo Clinic, Rochester, Minnesota.,Department of Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, Minnesota.,Department of Neurology, Mayo Clinic, Rochester, Minnesota
| | - Andrew G Engel
- Department of Neurology and Neuromuscular Research Laboratory, Mayo Clinic, Rochester, Minnesota
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23
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Nicole S, Azuma Y, Bauché S, Eymard B, Lochmüller H, Slater C. Congenital Myasthenic Syndromes or Inherited Disorders of Neuromuscular Transmission: Recent Discoveries and Open Questions. J Neuromuscul Dis 2019; 4:269-284. [PMID: 29125502 PMCID: PMC5701762 DOI: 10.3233/jnd-170257] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Congenital myasthenic syndromes (CMS) form a heterogeneous group of rare diseases characterized by fatigable muscle weakness. They are genetically-inherited and caused by defective synaptic transmission at the cholinergic neuromuscular junction (NMJ). The number of genes known to cause CMS when mutated is currently 30, and the relationship between fatigable muscle weakness and defective functions is quite well-understood for many of them. However, some of the most recent discoveries in individuals with CMS challenge our knowledge of the NMJ, where the basis of the pathology has mostly been investigated in animal models. Frontier forms between CMS and congenital myopathy, which have been genetically and clinically identified, underline the poorly understood interplay between the synaptic and extrasynaptic molecules in the neuromuscular system. In addition, precise electrophysiological and histopathological investigations of individuals with CMS suggest an important role of NMJ plasticity in the response to CMS pathogenesis. While efficient drug-based treatments are already available to improve neuromuscular transmission for most forms of CMS, others, as well as neurological and muscular comorbidities, remain resistant. Taken together, the available pathological data point to physiological issues which remain to be understood in order to achieve precision medicine with efficient therapeutics for all individuals suffering from CMS.
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Affiliation(s)
- Sophie Nicole
- Inserm U 1127, CNRS UMR 7225, Sorbonne Universités, UPMC Université Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle épinière, ICM, 75013 Paris, France
| | - Yoshiteru Azuma
- John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine, Newcastle University, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK
| | - Stéphanie Bauché
- Inserm U 1127, CNRS UMR 7225, Sorbonne Universités, UPMC Université Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle épinière, ICM, 75013 Paris, France
| | - Bruno Eymard
- Inserm U 1127, CNRS UMR 7225, Sorbonne Universités, UPMC Université Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle épinière, ICM, 75013 Paris, France.,AP-HP, Hôpital Pitié-Salpétrière, 75013 Paris, France
| | - Hanns Lochmüller
- John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine, Newcastle University, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK
| | - Clarke Slater
- Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK
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Abstract
OBJECTIVES Congenital myasthenic syndromes (CMSs) are a genotypically and phenotypically heterogeneous group of neuromuscular disorders, which have in common an impaired neuromuscular transmission. Since the field of CMSs is steadily expanding, the present review aimed at summarizing and discussing current knowledge and recent advances concerning the etiology, clinical presentation, diagnosis, and treatment of CMSs. METHODS Systematic literature review. RESULTS Currently, mutations in 32 genes are made responsible for autosomal dominant or autosomal recessive CMSs. These mutations concern 8 presynaptic, 4 synaptic, 15 post-synaptic, and 5 glycosilation proteins. These proteins function as ion-channels, enzymes, or structural, signalling, sensor, or transporter proteins. The most common causative genes are CHAT, COLQ, RAPSN, CHRNE, DOK7, and GFPT1. Phenotypically, these mutations manifest as abnormal fatigability or permanent or fluctuating weakness of extra-ocular, facial, bulbar, axial, respiratory, or limb muscles, hypotonia, or developmental delay. Cognitive disability, dysmorphism, neuropathy, or epilepsy are rare. Low- or high-frequency repetitive nerve stimulation may show an abnormal increment or decrement, and SF-EMG an increased jitter or blockings. Most CMSs respond favourably to acetylcholine-esterase inhibitors, 3,4-diamino-pyridine, salbutamol, albuterol, ephedrine, fluoxetine, or atracurium. CONCLUSIONS CMSs are an increasingly recognised group of genetically transmitted defects, which usually respond favorably to drugs enhancing the neuromuscular transmission. CMSs need to be differentiated from neuromuscular disorders due to muscle or nerve dysfunction.
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Affiliation(s)
- Josef Finsterer
- Krankenanstalt Rudolfstiftung, Messerli Institute, Veterinary University of Vienna, Postfach 20, 1180, Vienna, Austria.
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25
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Targeted therapies for congenital myasthenic syndromes: systematic review and steps towards a treatabolome. Emerg Top Life Sci 2019; 3:19-37. [PMID: 30931400 PMCID: PMC6436731 DOI: 10.1042/etls20180100] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Despite recent scientific advances, most rare genetic diseases — including most neuromuscular diseases — do not currently have curative gene-based therapies available. However, in some cases, such as vitamin, cofactor or enzyme deficiencies, channelopathies and disorders of the neuromuscular junction, a confirmed genetic diagnosis provides guidance on treatment, with drugs available that may significantly alter the disease course, improve functional ability and extend life expectancy. Nevertheless, many treatable patients remain undiagnosed or do not receive treatment even after genetic diagnosis. The growth of computer-aided genetic analysis systems that enable clinicians to diagnose their undiagnosed patients has not yet been matched by genetics-based decision-support systems for treatment guidance. Generating a ‘treatabolome’ of treatable variants and the evidence for the treatment has the potential to increase treatment rates for treatable conditions. Here, we use the congenital myasthenic syndromes (CMS), a group of clinically and genetically heterogeneous but frequently treatable neuromuscular conditions, to illustrate the steps in the creation of a treatabolome for rare inherited diseases. We perform a systematic review of the evidence for pharmacological treatment of each CMS type, gathering evidence from 207 studies of over 1000 patients and stratifying by genetic defect, as treatment varies depending on the underlying cause. We assess the strength and quality of the evidence and create a dataset that provides the foundation for a computer-aided system to enable clinicians to gain easier access to information about treatable variants and the evidence they need to consider.
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26
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Italian recommendations for diagnosis and management of congenital myasthenic syndromes. Neurol Sci 2018; 40:457-468. [PMID: 30554356 DOI: 10.1007/s10072-018-3682-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Accepted: 12/10/2018] [Indexed: 12/11/2022]
Abstract
Congenital myasthenic syndromes (CMS) are genetic disorders due to mutations in genes encoding proteins involved in the neuromuscular junction structure and function. CMS usually present in young children, but perinatal and adult onset has been reported. Clinical presentation is highly heterogeneous, ranging from mild symptoms to severe manifestations, sometimes with life-threatening respiratory episodes, especially in the first decade of life. Although considered rare, CMS are probably underestimated due to diagnostic difficulties. Because of the several therapeutic opportunities, CMS should be always considered in the differential diagnosis of neuromuscular disorders. The Italian Network on CMS proposes here recommendations for proper CMS diagnosis and management, aiming to guide clinicians in their practical approach to CMS patients.
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[Congenital myasthenic syndromes in adulthood : Challenging, rare but treatable]. DER NERVENARZT 2018; 90:148-159. [PMID: 29974128 DOI: 10.1007/s00115-018-0562-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
The congenital myasthenic syndromes (CMS) represent a heterogeneous group of diseases with a broad spectrum of phenotypes. The common characteristic is an inherited genetic defect of the neuromuscular junction. Although in some patients the specific gene defect remains to be detected, the increasing identification of causative genes in recent years has already provided unique insights into the functionality of structural proteins at the neuromuscular junction. Neonatal and early childhood onset is observed in most CMS subtypes; however, late onset in adolescence or adulthood also occurs and establishing the diagnosis at these stages imposes particular challenges. To enable appropriate therapeutic interventions for an at least in principle treatable condition, determining the genetic cause is warranted. In this overview, the critical clinical and diagnostic features of the different CMS subtypes are presented and illustrated using typical cases. Furthermore, specific diagnostic clues are outlined. Finally, the overlap between CMS and muscular dystrophies is discussed. Illustrating characteristic patient examples, the essential clinical and additional diagnostic findings of various CMS subtypes and special diagnostic indications are presented.
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Rodríguez Cruz PM, Palace J, Beeson D. The Neuromuscular Junction and Wide Heterogeneity of Congenital Myasthenic Syndromes. Int J Mol Sci 2018; 19:ijms19061677. [PMID: 29874875 PMCID: PMC6032286 DOI: 10.3390/ijms19061677] [Citation(s) in RCA: 70] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Revised: 05/17/2018] [Accepted: 05/21/2018] [Indexed: 01/16/2023] Open
Abstract
Congenital myasthenic syndromes (CMS) are genetic disorders characterised by impaired neuromuscular transmission. This review provides an overview on CMS and highlights recent advances in the field, including novel CMS causative genes and improved therapeutic strategies. CMS due to mutations in SLC5A7 and SLC18A3, impairing the synthesis and recycling of acetylcholine, have recently been described. In addition, a novel group of CMS due to mutations in SNAP25B, SYT2, VAMP1, and UNC13A1 encoding molecules implicated in synaptic vesicles exocytosis has been characterised. The increasing number of presynaptic CMS exhibiting CNS manifestations along with neuromuscular weakness demonstrate that the myasthenia can be only a small part of a much more extensive disease phenotype. Moreover, the spectrum of glycosylation abnormalities has been increased with the report that GMPPB mutations can cause CMS, thus bridging myasthenic disorders with dystroglycanopathies. Finally, the discovery of COL13A1 mutations and laminin α5 deficiency has helped to draw attention to the role of extracellular matrix proteins for the formation and maintenance of muscle endplates. The benefit of β2-adrenergic agonists alone or combined with pyridostigmine or 3,4-Dyaminopiridine is increasingly being reported for different subtypes of CMS including AChR-deficiency and glycosylation abnormalities, thus expanding the therapeutic repertoire available.
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Affiliation(s)
- Pedro M Rodríguez Cruz
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK.
- Neurosciences Group, Weatherall Institute of Molecular Medicine, University of Oxford, The John Radcliffe Hospital, Oxford OX3 9DS, UK.
| | - Jacqueline Palace
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK.
| | - David Beeson
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK.
- Neurosciences Group, Weatherall Institute of Molecular Medicine, University of Oxford, The John Radcliffe Hospital, Oxford OX3 9DS, UK.
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Durmus H, Shen XM, Serdaroglu-Oflazer P, Kara B, Parman-Gulsen Y, Ozdemir C, Brengman J, Deymeer F, Engel AG. Congenital myasthenic syndromes in Turkey: Clinical clues and prognosis with long term follow-up. Neuromuscul Disord 2018; 28:315-322. [PMID: 29395675 PMCID: PMC5924610 DOI: 10.1016/j.nmd.2017.11.013] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Revised: 11/07/2017] [Accepted: 11/20/2017] [Indexed: 11/28/2022]
Abstract
Congenital myasthenic syndromes (CMS) are a group of hereditary disorders affecting the neuromuscular junction. Here, we present clinical, electrophysiological and genetic findings of 69 patients from 51 unrelated kinships from Turkey. Genetic tests of 60 patients were performed at Mayo Clinic. Median follow-up time was 9.8 years (range 1-22 years). The most common CMS was primary acetylcholine receptor (AChR) deficiency (31/51) and the most common mutations in AChR were c.1219 + 2T > G (12/51) and c.1327delG (6/51) in CHRNE. Four of our 5 kinships with AChE deficiency carried p.W148X that truncates the collagen domain of COLQ, and was previously reported only in patients from Turkey. These were followed by GFPT1 deficiency (4/51), DOK7 deficiency (3/51), slow channel CMS (3/51), fast channel CMS (3/51), choline acetyltransferase deficiency (1/51) and a CMS associated with desmin deficiency (1/51). Distribution of muscle weakness was sometimes useful in giving a clue to the CMS subtype. Presence of repetitive compound muscle action potentials pointed to AChE deficiency or slow channel CMS. Our experience confirms that one needs to be cautious using pyridostigmine, since it can worsen some types of CMS. Ephedrine/salbutamol were very effective in AChE and DOK7 deficiencies and were useful as adjuncts in other types of CMS. Long follow-up gave us a chance to assess progression of the disease, and to witness 12 mainly uneventful pregnancies in 8 patients. In this study, we describe some new phenotypes and detail the clinical features of the well-known CMS.
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Affiliation(s)
- Hacer Durmus
- Department of Neurology, Istanbul Medical Faculty, Istanbul University, Capa, 34390, Istanbul, Turkey
| | - Xin-Ming Shen
- Department of Neurology, Mayo Clinic, Rochester, MN, USA
| | - Piraye Serdaroglu-Oflazer
- Department of Neurology, Istanbul Medical Faculty, Istanbul University, Capa, 34390, Istanbul, Turkey
| | - Bulent Kara
- Department of Neurology, Istanbul Medical Faculty, Istanbul University, Capa, 34390, Istanbul, Turkey
| | - Yesim Parman-Gulsen
- Department of Neurology, Istanbul Medical Faculty, Istanbul University, Capa, 34390, Istanbul, Turkey
| | - Coskun Ozdemir
- Department of Neurology, Istanbul Medical Faculty, Istanbul University, Capa, 34390, Istanbul, Turkey
| | - Joan Brengman
- Department of Neurology, Mayo Clinic, Rochester, MN, USA
| | - Feza Deymeer
- Department of Neurology, Istanbul Medical Faculty, Istanbul University, Capa, 34390, Istanbul, Turkey.
| | - Andrew G Engel
- Department of Neurology, Mayo Clinic, Rochester, MN, USA
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Dowling JJ, D. Gonorazky H, Cohn RD, Campbell C. Treating pediatric neuromuscular disorders: The future is now. Am J Med Genet A 2018; 176:804-841. [PMID: 28889642 PMCID: PMC5900978 DOI: 10.1002/ajmg.a.38418] [Citation(s) in RCA: 74] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Accepted: 07/31/2017] [Indexed: 12/12/2022]
Abstract
Pediatric neuromuscular diseases encompass all disorders with onset in childhood and where the primary area of pathology is in the peripheral nervous system. These conditions are largely genetic in etiology, and only those with a genetic underpinning will be presented in this review. This includes disorders of the anterior horn cell (e.g., spinal muscular atrophy), peripheral nerve (e.g., Charcot-Marie-Tooth disease), the neuromuscular junction (e.g., congenital myasthenic syndrome), and the muscle (myopathies and muscular dystrophies). Historically, pediatric neuromuscular disorders have uniformly been considered to be without treatment possibilities and to have dire prognoses. This perception has gradually changed, starting in part with the discovery and widespread application of corticosteroids for Duchenne muscular dystrophy. At present, several exciting therapeutic avenues are under investigation for a range of conditions, offering the potential for significant improvements in patient morbidities and mortality and, in some cases, curative intervention. In this review, we will present the current state of treatment for the most common pediatric neuromuscular conditions, and detail the treatment strategies with the greatest potential for helping with these devastating diseases.
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Affiliation(s)
- James J. Dowling
- Division of NeurologyHospital for Sick ChildrenTorontoOntarioCanada
- Program for Genetics and Genome BiologyHospital for Sick ChildrenTorontoOntarioCanada
- Departments of Paediatrics and Molecular GeneticsUniversity of TorontoTorontoOntarioCanada
| | | | - Ronald D. Cohn
- Program for Genetics and Genome BiologyHospital for Sick ChildrenTorontoOntarioCanada
- Departments of Paediatrics and Molecular GeneticsUniversity of TorontoTorontoOntarioCanada
| | - Craig Campbell
- Department of PediatricsClinical Neurological SciencesEpidemiologyWestern UniversityLondonOntarioCanada
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31
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Lee M, Beeson D, Palace J. Therapeutic strategies for congenital myasthenic syndromes. Ann N Y Acad Sci 2018; 1412:129-136. [DOI: 10.1111/nyas.13538] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Revised: 09/28/2017] [Accepted: 10/02/2017] [Indexed: 12/20/2022]
Affiliation(s)
- Manon Lee
- Nuffield Department of Clinical Neurosciences; John Radcliffe Hospital; Oxford United Kingdom
| | - David Beeson
- The Weatherall Institute of Molecular Medicine, John Radcliffe Hospital; University of Oxford; Oxford United Kingdom
| | - Jacqueline Palace
- Nuffield Department of Clinical Neurosciences; John Radcliffe Hospital; Oxford United Kingdom
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32
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Engel AG. Genetic basis and phenotypic features of congenital myasthenic syndromes. HANDBOOK OF CLINICAL NEUROLOGY 2018; 148:565-589. [PMID: 29478601 DOI: 10.1016/b978-0-444-64076-5.00037-5] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/06/2022]
Abstract
The congenital myasthenic syndromes (CMS) are heterogeneous disorders in which the safety margin of neuromuscular transmission is compromised by one or more specific mechanisms. The disease proteins reside in the nerve terminal, the synaptic basal lamina, or in the postsynaptic region, or at multiple sites at the neuromuscular junction as well as in other tissues. Targeted mutation analysis by Sanger or exome sequencing has been facilitated by characteristic phenotypic features of some CMS. No fewer than 20 disease genes have been recognized to date. In one-half of the currently identified probands, the disease stems from mutations in genes encoding subunits of the muscle form of the acetylcholine receptor (CHRNA1, CHRNB, CHRNAD1, and CHRNE). In 10-14% of the probands the disease is caused by mutations in RAPSN, DOK 7, or COLQ, and in 5% by mutations in CHAT. Other less frequently identified disease genes include LAMB2, AGRN, LRP4, MUSK, GFPT1, DPAGT1, ALG2, and ALG 14 as well as SCN4A, PREPL, PLEC1, DNM2, and MTM1. Identification of the genetic basis of each CMS is important not only for genetic counseling and disease prevention but also for therapy, because therapeutic agents that benefit one type of CMS can be harmful in another.
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Affiliation(s)
- Andrew G Engel
- Department of Neurology, Mayo Clinic College of Medicine, Rochester, MN, United States.
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33
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Hernández-Abrego A, Vázquez-Gómez E, García-Colunga J. Effects of the antidepressant mirtazapine and zinc on nicotinic acetylcholine receptors. Neurosci Lett 2017; 665:246-251. [PMID: 29225093 DOI: 10.1016/j.neulet.2017.12.016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Revised: 11/29/2017] [Accepted: 12/06/2017] [Indexed: 12/23/2022]
Abstract
Nicotinic acetylcholine receptors (nAChRs) and zinc are associated with regulation of mood and related disorders. In addition, several antidepressants inhibit muscle and neuronal nAChRs and zinc potentiates inhibitory actions of them. Moreover, mirtazapine (a noradrenergic, serotonergic and histaminergic antidepressant) inhibits muscarinic AChRs and its effects on nAChRs are unknown. Therefore, we studied the modulation of muscle α1β1γd nAChRs expressed in oocytes and native α7-containing nAChRs in hippocampal interneurons by mirtazapine and/or zinc, using voltage-clamp techniques. The currents elicited by ACh in oocytes (at -60 mV) were similarly inhibited by mirtazapine in the absence and presence of 100 μM zinc (IC50 ∼15 μM); however, the ACh-induced currents were stronger inhibited with 20 and 50 μM mirtazapine in the presence of zinc. Furthermore, the potentiation of ACh-induced current by zinc in the presence of 5 μM mirtazapine was 1.48 ± 0.06, and with 50 μM mirtazapine zinc potentiation did not occur. Interestingly, in stratum radiatum interneurons (at -70 mV), 20 μM mirtazapine showed less inhibition of the current elicited by choline (Ch) than at 10 μM (0.81 ± 0.02 and 0.74 ± 0.02 of the Ch-induced current, respectively). Finally, the inhibitory effects of mirtazapine depended on membrane potential: 0.81 ± 0.02 and 0.56 ± 0.05 of the control Ch-induced current at -70 and -20 mV, respectively. These results indicate that mirtazapine interacts with muscle and neuronal nAChRs, possibly into the ion channel; that zinc may increase the sensitivity of nAChRs to mirtazapine; and that mirtazapine decreases the sensitivity of nAChRs to zinc.
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Affiliation(s)
- Andy Hernández-Abrego
- Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus Juriquilla, Boulevard Juriquilla 3001, Juriquilla, Querétaro 76230, México
| | - Elizabeth Vázquez-Gómez
- Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus Juriquilla, Boulevard Juriquilla 3001, Juriquilla, Querétaro 76230, México
| | - Jesús García-Colunga
- Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus Juriquilla, Boulevard Juriquilla 3001, Juriquilla, Querétaro 76230, México.
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34
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Natera-de Benito D, Töpf A, Vilchez JJ, González-Quereda L, Domínguez-Carral J, Díaz-Manera J, Ortez C, Bestué M, Gallano P, Dusl M, Abicht A, Müller JS, Senderek J, García-Ribes A, Muelas N, Evangelista T, Azuma Y, McMacken G, Paipa Merchan A, Rodríguez Cruz PM, Camacho A, Jiménez E, Miranda-Herrero MC, Santana-Artiles A, García-Campos O, Dominguez-Rubio R, Olivé M, Colomer J, Beeson D, Lochmüller H, Nascimento A. Molecular characterization of congenital myasthenic syndromes in Spain. Neuromuscul Disord 2017; 27:1087-1098. [PMID: 29054425 DOI: 10.1016/j.nmd.2017.08.003] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Revised: 08/08/2017] [Accepted: 08/10/2017] [Indexed: 10/19/2022]
Abstract
Congenital myasthenic syndromes (CMS) are a heterogeneous group of genetic disorders, all of which impair neuromuscular transmission. Epidemiological data and frequencies of gene mutations are scarce in the literature. Here we describe the molecular genetic and clinical findings of sixty-four genetically confirmed CMS patients from Spain. Thirty-six mutations in the CHRNE, RAPSN, COLQ, GFPT1, DOK7, CHRNG, GMPPB, CHAT, CHRNA1, and CHRNB1 genes were identified in our patients, with five of them not reported so far. These data provide an overview on the relative frequencies of the different CMS subtypes in a large Spanish population. CHRNE mutations are the most common cause of CMS in Spain, accounting for 27% of the total. The second most common are RAPSN mutations. We found a higher rate of GFPT1 mutations in comparison with other populations. Remarkably, several founder mutations made a large contribution to CMS in Spain: RAPSN c.264C > A (p.Asn88Lys), CHRNE c.130insG (Glu44Glyfs*3), CHRNE c.1353insG (p.Asn542Gluf*4), DOK7 c.1124_1127dup (p.Ala378Serfs*30), and particularly frequent in Spain in comparison with other populations, COLQ c.1289A > C (p.Tyr430Ser). Furthermore, we describe phenotypes and distinguishing clinical signs associated with the various CMS genes which might help to identify specific CMS subtypes to guide diagnosis and management.
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Affiliation(s)
- D Natera-de Benito
- Department of Neuromuscular Diseases, Hospital Sant Joan de Déu, CIBERER U703, Barcelona, Spain.
| | - A Töpf
- John Walton Muscular Dystrophy Research Centre, MRC Centre for Neuromuscular Diseases, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne NE1 3BZ, UK
| | - J J Vilchez
- Department of Neurology, Hospital Universitari La Fe, Universitat de Valencia, CIBERER U763, Valencia, Spain
| | - L González-Quereda
- Department of Genetics, Hospital de la Santa Creu i Sant Pau and CIBERER U705, Barcelona, Spain
| | - J Domínguez-Carral
- Department of Pediatrics, Hospital Universitario Marqués de Valdecilla, Santander, Spain
| | - J Díaz-Manera
- Neuromuscular Diseases Unit, Department of Neurology, Hospital de la Santa Creu i Sant Pau, Universitat Autònoma de Barcelona and Centre for Biomedical Network Research on Rare Diseases (CIBERER), Barcelona, Spain
| | - C Ortez
- Department of Neuromuscular Diseases, Hospital Sant Joan de Déu, CIBERER U703, Barcelona, Spain
| | - M Bestué
- Department of Neurology, Hospital General San Jorge, Huesca, Spain
| | - P Gallano
- Department of Genetics, Hospital de la Santa Creu i Sant Pau and CIBERER U705, Barcelona, Spain
| | - M Dusl
- Friedrich-Baur-Institute, Ludwig-Maximilians-University Munich, 80336 Munich, Germany
| | - A Abicht
- Friedrich-Baur-Institute, Ludwig-Maximilians-University Munich, 80336 Munich, Germany; Medical Genetics Center, Munich, Germany
| | - J S Müller
- Wellcome Trust Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
| | - J Senderek
- Friedrich-Baur-Institute, Ludwig-Maximilians-University Munich, 80336 Munich, Germany
| | - A García-Ribes
- Department of Pediatrics, Hospital Universitario Cruces, Bilbao, Spain
| | - N Muelas
- Department of Neurology, Hospital Universitari La Fe, Universitat de Valencia, CIBERER U763, Valencia, Spain
| | - T Evangelista
- John Walton Muscular Dystrophy Research Centre, MRC Centre for Neuromuscular Diseases, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne NE1 3BZ, UK
| | - Y Azuma
- John Walton Muscular Dystrophy Research Centre, MRC Centre for Neuromuscular Diseases, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne NE1 3BZ, UK
| | - G McMacken
- John Walton Muscular Dystrophy Research Centre, MRC Centre for Neuromuscular Diseases, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne NE1 3BZ, UK
| | - A Paipa Merchan
- Neuropathology Unit, Department of Pathology and Neuromuscular Unit, IDIBELL-Hospital Universitari de Bellvitge, Barcelona, Spain
| | - P M Rodríguez Cruz
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, UK
| | - A Camacho
- Department of Pediatric Neurology, Hospital Universitario 12 de Octubre, Madrid, Spain
| | - E Jiménez
- Department of Pediatrics, Hospital Universitario Rey Juan Carlos, Madrid, Spain
| | - M C Miranda-Herrero
- Department of Neuropediatrics, Hospital General Universitario Gregorio Marañón, Madrid, Spain
| | - A Santana-Artiles
- Department of Neuropediatrics, Complejo Hospitalario Universitario Insular Materno-Infantil, Las Palmas de Gran Canaria, Spain
| | - O García-Campos
- Department of Neuropediatrics, Hospital Virgen de la Salud, Toledo, Spain
| | - R Dominguez-Rubio
- Neuropathology Unit, Department of Pathology and Neuromuscular Unit, IDIBELL-Hospital Universitari de Bellvitge, Barcelona, Spain
| | - M Olivé
- Neuropathology Unit, Department of Pathology and Neuromuscular Unit, IDIBELL-Hospital Universitari de Bellvitge, Barcelona, Spain
| | - J Colomer
- Department of Neuromuscular Diseases, Hospital Sant Joan de Déu, CIBERER U703, Barcelona, Spain
| | - D Beeson
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, UK
| | - H Lochmüller
- John Walton Muscular Dystrophy Research Centre, MRC Centre for Neuromuscular Diseases, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne NE1 3BZ, UK
| | - A Nascimento
- Department of Neuromuscular Diseases, Hospital Sant Joan de Déu, CIBERER U703, Barcelona, Spain
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Mutations in GFPT1-related congenital myasthenic syndromes are associated with synaptic morphological defects and underlie a tubular aggregate myopathy with synaptopathy. J Neurol 2017; 264:1791-1803. [DOI: 10.1007/s00415-017-8569-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Revised: 07/03/2017] [Accepted: 07/11/2017] [Indexed: 12/22/2022]
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Ghosh PS. Clinical Reasoning: A child with delayed motor milestones and ptosis. Neurology 2017; 88:e158-e163. [DOI: 10.1212/wnl.0000000000003844] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Shen XM, Okuno T, Milone M, Otsuka K, Takahashi K, Komaki H, Giles E, Ohno K, Engel AG. Mutations Causing Slow-Channel Myasthenia Reveal That a Valine Ring in the Channel Pore of Muscle AChR is Optimized for Stabilizing Channel Gating. Hum Mutat 2016; 37:1051-9. [PMID: 27375219 DOI: 10.1002/humu.23043] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Revised: 06/18/2016] [Accepted: 06/23/2016] [Indexed: 12/22/2022]
Abstract
We identify two novel mutations in acetylcholine receptor (AChR) causing a slow-channel congenital myasthenia syndrome (CMS) in three unrelated patients (Pts). Pt 1 harbors a heterozygous βV266A mutation (p.Val289Ala) in the second transmembrane domain (M2) of the AChR β subunit (CHRNB1). Pts 2 and 3 carry the same mutation at an equivalent site in the ε subunit (CHRNE), εV265A (p.Val285Ala). The mutant residues are conserved across all AChR subunits of all species and are components of a valine ring in the channel pore, which is positioned four residues above the leucine ring. Both βV266A and εV265A reduce the amino acid size and lengthen the channel opening bursts by fourfold by enhancing gating efficiency by approximately 30-fold. Substitution of alanine for valine at the corresponding position in the δ and α subunit prolongs the burst duration four- and eightfold, respectively. Replacing valine at ε codon 265 either by a still smaller glycine or by a larger leucine also lengthens the burst duration. Our analysis reveals that each valine in the valine ring contributes to channel kinetics equally, and the valine ring has been optimized in the course of evolution to govern channel gating.
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Affiliation(s)
- Xin-Ming Shen
- Department of Neurology, Mayo Clinic, Rochester, Minnesota. ,
| | - Tatsuya Okuno
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | | | - Kenji Otsuka
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Koji Takahashi
- Department of Child Neurology, National Center Hospital of Neurology and Psychiatry, Tokyo, Japan
| | - Hirofumi Komaki
- Department of Child Neurology, National Center Hospital of Neurology and Psychiatry, Tokyo, Japan
| | | | - Kinji Ohno
- Department of Neurology, Mayo Clinic, Rochester, Minnesota.,Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Andrew G Engel
- Department of Neurology, Mayo Clinic, Rochester, Minnesota
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38
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Rodríguez Cruz PM, Belaya K, Basiri K, Sedghi M, Farrugia ME, Holton JL, Liu WW, Maxwell S, Petty R, Walls TJ, Kennett R, Pitt M, Sarkozy A, Parton M, Lochmüller H, Muntoni F, Palace J, Beeson D. Clinical features of the myasthenic syndrome arising from mutations in GMPPB. J Neurol Neurosurg Psychiatry 2016; 87:802-9. [PMID: 27147698 PMCID: PMC6047737 DOI: 10.1136/jnnp-2016-313163] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Accepted: 03/31/2016] [Indexed: 11/04/2022]
Abstract
BACKGROUND Congenital myasthenic syndrome (CMS) due to mutations in GMPPB has recently been reported confirming the importance of glycosylation for the integrity of neuromuscular transmission. METHODS Review of case notes of patients with mutations in GMPPB to identify the associated clinical, neurophysiological, pathological and laboratory features. In addition, serum creatine kinase (CK) levels within the Oxford CMS cohort were retrospectively analysed to assess its usefulness in the differential diagnosis of this new entity. RESULTS All patients had prominent limb-girdle weakness with minimal or absent craniobulbar manifestations. Presentation was delayed beyond infancy with proximal muscle weakness and most patients recall poor performance in sports during childhood. Neurophysiology showed abnormal neuromuscular transmission only in the affected muscles and myopathic changes. Muscle biopsy showed dystrophic features and reduced α-dystroglycan glycosylation. In addition, myopathic changes were present on muscle MRI. CK was significantly increased in serum compared to other CMS subtypes. Patients were responsive to pyridostigimine alone or combined with 3,4-diaminopyridine and/or salbutamol. CONCLUSIONS Patients with GMPPB-CMS have phenotypic features aligned with CMS subtypes harbouring mutations within the early stages of the glycosylation pathway. Additional features shared with the dystroglycanopathies include myopathic features, raised CK levels and variable mild cognitive delay. This syndrome underlines that CMS can occur in the absence of classic myasthenic manifestations such as ptosis and ophthalmoplegia or facial weakness, and links myasthenic disorders with dystroglycanopathies. This report should facilitate the recognition of this disorder, which is likely to be underdiagnosed and can benefit from symptomatic treatment.
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Affiliation(s)
- Pedro M Rodríguez Cruz
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, Oxford, UK
| | - Katsiaryna Belaya
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
| | - Keivan Basiri
- Neurology Department, Neuroscience Research Centre, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Maryam Sedghi
- Medical Genetics Laboratory, Alzahra University Hospital, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Maria Elena Farrugia
- Department of Neurology, Institute of Neurological Sciences, The Queen Elizabeth University Hospital, Glasgow, UK
| | - Janice L Holton
- Department of Molecular Neurosciences, UCL Institute of Neurology, London, UK MRC Centre for Neuromuscular Diseases, UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery, London, UK
| | - Wei Wei Liu
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
| | - Susan Maxwell
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
| | - Richard Petty
- Department of Neurology, Institute of Neurological Sciences, The Queen Elizabeth University Hospital, Glasgow, UK
| | - Timothy J Walls
- Department of Neurology, Royal Victoria Infirmary, Newcastle upon Tyne, UK
| | - Robin Kennett
- Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, Oxford, UK
| | - Matthew Pitt
- Department of Clinical Neurophysiology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Anna Sarkozy
- MRC Centre for Neuromuscular Diseases, UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery, London, UK
| | - Matt Parton
- MRC Centre for Neuromuscular Diseases, UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery, London, UK
| | - Hanns Lochmüller
- Institute of Genetic Medicine, John Walton Muscular Dystrophy Research Centre, MRC Centre for Neuromuscular Diseases, Newcastle University, Newcastle upon Tyne, UK
| | - Francesco Muntoni
- Dubowitz Neuromuscular Centre & MRC Centre for Neuromuscular Diseases, UCL Institute of Child Health, London, UK
| | - Jacqueline Palace
- Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, Oxford, UK
| | - David Beeson
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
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Finlayson S, Morrow JM, Rodriguez Cruz PM, Sinclair CDJ, Fischmann A, Thornton JS, Knight S, Norbury R, White M, Al-Hajjar M, Carboni N, Jayawant S, Robb SA, Yousry TA, Beeson D, Palace J. Muscle magnetic resonance imaging in congenital myasthenic syndromes. Muscle Nerve 2016; 54:211-9. [PMID: 26789134 PMCID: PMC4982021 DOI: 10.1002/mus.25035] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Revised: 12/27/2015] [Accepted: 01/06/2016] [Indexed: 11/26/2022]
Abstract
Introduction In this study we investigated muscle magnetic resonance imaging in congenital myasthenic syndromes (CMS). Methods Twenty‐six patients with 9 CMS subtypes and 10 controls were imaged. T1‐weighted (T1w) and short‐tau inversion recovery (STIR) 3‐Tesla MRI images obtained at thigh and calf levels were scored for severity. Results Overall mean the T1w score was increased in GFPT1 and DPAGT1 CMS. T1w scans of the AChR‐deficiency, COLQ, and CHAT subjects were indistinguishable from controls. STIR images from CMS patients did not differ significantly from those of controls. Mean T1w score correlated with age in the CMS cohort. Conclusions MRI appearances ranged from normal to marked abnormality. T1w images seem to be especially abnormal in some CMS caused by mutations of proteins involved in the glycosylation pathway. A non‐selective pattern of fat infiltration or a normal‐appearing scan in the setting of significant clinical weakness should suggest CMS as a potential diagnosis. Muscle MRI could play a role in differentiating CMS subtypes. Muscle Nerve54: 211–219, 2016
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Affiliation(s)
- Sarah Finlayson
- Nuffield Department of Clinical Neurosciences, University of Oxford and Oxford Radcliffe Hospitals NHS Trust, Oxford, UK
| | - Jasper M Morrow
- MRC Centre for Neuromuscular Diseases, UCL Institute of Neurology, London, UK
| | - Pedro M Rodriguez Cruz
- Nuffield Department of Clinical Neurosciences, University of Oxford and Oxford Radcliffe Hospitals NHS Trust, Oxford, UK
| | | | - Arne Fischmann
- MRC Centre for Neuromuscular Diseases, UCL Institute of Neurology, London, UK
| | - John S Thornton
- MRC Centre for Neuromuscular Diseases, UCL Institute of Neurology, London, UK
| | - Steve Knight
- University of Oxford Centre for Clinical Magnetic Resonance Research, John Radcliffe Hospital, Oxford, UK
| | - Ray Norbury
- University of Oxford Centre for Clinical Magnetic Resonance Research, John Radcliffe Hospital, Oxford, UK
| | - Mel White
- Department of Paediatrics, University of Oxford and Children's Hospital, Oxford, UK
| | - Michal Al-Hajjar
- Nuffield Department of Clinical Neurosciences, University of Oxford and Oxford Radcliffe Hospitals NHS Trust, Oxford, UK
| | - Nicola Carboni
- Neurology Department, Hospital San Francesco of Nuoro, Sardinia, Italy
| | - Sandeep Jayawant
- Department of Paediatrics, University of Oxford and Children's Hospital, Oxford, UK
| | - Stephanie A Robb
- Dubowitz Neuromuscular Centre, Institute of Child Health and Great Ormond Street Hospital, London, UK
| | - Tarek A Yousry
- MRC Centre for Neuromuscular Diseases, UCL Institute of Neurology, London, UK
| | - David Beeson
- Neurosciences Group, Weatherall Institute of Molecular Medicine, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Jacqueline Palace
- Nuffield Department of Clinical Neurosciences, University of Oxford and Oxford Radcliffe Hospitals NHS Trust, Oxford, UK
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Spillane J, Kullmann DM, Hanna MG. Genetic neurological channelopathies: molecular genetics and clinical phenotypes. J Neurol Neurosurg Psychiatry 2016; 87:37-48. [PMID: 26558925 PMCID: PMC4717447 DOI: 10.1136/jnnp-2015-311233] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Accepted: 09/13/2015] [Indexed: 01/08/2023]
Abstract
Evidence accumulated over recent years has shown that genetic neurological channelopathies can cause many different neurological diseases. Presentations relating to the brain, spinal cord, peripheral nerve or muscle mean that channelopathies can impact on almost any area of neurological practice. Typically, neurological channelopathies are inherited in an autosomal dominant fashion and cause paroxysmal disturbances of neurological function, although the impairment of function can become fixed with time. These disorders are individually rare, but an accurate diagnosis is important as it has genetic counselling and often treatment implications. Furthermore, the study of less common ion channel mutation-related diseases has increased our understanding of pathomechanisms that is relevant to common neurological diseases such as migraine and epilepsy. Here, we review the molecular genetic and clinical features of inherited neurological channelopathies.
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Affiliation(s)
- J Spillane
- Royal Free Hospital Foundation Trust London, London, UK MRC Centre for Neuromuscular Disease, UCL, London, UK
| | - D M Kullmann
- MRC Centre for Neuromuscular Disease, UCL, London, UK UCL, Institute of Neurology, London, UK
| | - M G Hanna
- MRC Centre for Neuromuscular Disease, UCL, London, UK UCL, Institute of Neurology, London, UK
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41
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Belaya K, Rodríguez Cruz PM, Liu WW, Maxwell S, McGowan S, Farrugia ME, Petty R, Walls TJ, Sedghi M, Basiri K, Yue WW, Sarkozy A, Bertoli M, Pitt M, Kennett R, Schaefer A, Bushby K, Parton M, Lochmüller H, Palace J, Muntoni F, Beeson D. Mutations in GMPPB cause congenital myasthenic syndrome and bridge myasthenic disorders with dystroglycanopathies. Brain 2015; 138:2493-504. [PMID: 26133662 PMCID: PMC4547052 DOI: 10.1093/brain/awv185] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Accepted: 05/04/2015] [Indexed: 01/10/2023] Open
Abstract
Congenital myasthenic syndromes are associated with impairments in neuromuscular transmission. Belaya et al. show that mutations of the glycosylation pathway enzyme GMPPB, which has previously been implicated in muscular dystrophy dystroglycanopathy, also cause a congenital myasthenic syndrome. This differential diagnosis is important to ensure that affected individuals receive appropriate medication. Congenital myasthenic syndromes are inherited disorders that arise from impaired signal transmission at the neuromuscular junction. Mutations in at least 20 genes are known to lead to the onset of these conditions. Four of these, ALG2, ALG14, DPAGT1 and GFPT1, are involved in glycosylation. Here we identify a fifth glycosylation gene, GMPPB, where mutations cause congenital myasthenic syndrome. First, we identified recessive mutations in seven cases from five kinships defined as congenital myasthenic syndrome using decrement of compound muscle action potentials on repetitive nerve stimulation on electromyography. The mutations were present through the length of the GMPPB, and segregation, in silico analysis, exon trapping, cell transfection followed by western blots and immunostaining were used to determine pathogenicity. GMPPB congenital myasthenic syndrome cases show clinical features characteristic of congenital myasthenic syndrome subtypes that are due to defective glycosylation, with variable weakness of proximal limb muscle groups while facial and eye muscles are largely spared. However, patients with GMPPB congenital myasthenic syndrome had more prominent myopathic features that were detectable on muscle biopsies, electromyography, muscle magnetic resonance imaging, and through elevated serum creatine kinase levels. Mutations in GMPPB have recently been reported to lead to the onset of muscular dystrophy dystroglycanopathy. Analysis of four additional GMPPB-associated muscular dystrophy dystroglycanopathy cases by electromyography found that a defective neuromuscular junction component is not always present. Thus, we find mutations in GMPPB can lead to a wide spectrum of clinical features where deficit in neuromuscular transmission is the major component in a subset of cases. Clinical recognition of GMPPB-associated congenital myasthenic syndrome may be complicated by the presence of myopathic features, but correct diagnosis is important because affected individuals can respond to appropriate treatments.
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Affiliation(s)
- Katsiaryna Belaya
- 1 Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, OX3 9DS, UK
| | - Pedro M Rodríguez Cruz
- 1 Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, OX3 9DS, UK 2 Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, Oxford, OX3 9DU, UK
| | - Wei Wei Liu
- 1 Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, OX3 9DS, UK
| | - Susan Maxwell
- 1 Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, OX3 9DS, UK
| | - Simon McGowan
- 3 Computational Biology Research Group, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, OX3 9DS, UK
| | - Maria E Farrugia
- 4 Department of Neurology, Institute of Neurological Sciences, Southern General Hospital, Glasgow, UK
| | - Richard Petty
- 4 Department of Neurology, Institute of Neurological Sciences, Southern General Hospital, Glasgow, UK
| | - Timothy J Walls
- 5 Department of Neurology, Royal Victoria Infirmary, Newcastle upon Tyne, NE1 4LP, UK
| | - Maryam Sedghi
- 6 Medical Genetics Laboratory, Alzahra University Hospital, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Keivan Basiri
- 7 Neurology Department, Neuroscience Research Centre, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Wyatt W Yue
- 8 Structural Genomics Consortium, University of Oxford, Oxford, OX3 7DQ, UK
| | - Anna Sarkozy
- 9 Institute of Genetic Medicine, John Walton Muscular Dystrophy Research Centre, MRC Centre for Neuromuscular Diseases, Newcastle University, Newcastle upon Tyne, NE1 3BZ, UK 10 MRC Centre for Neuromuscular Diseases, UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery, Queen Square, London, UK
| | - Marta Bertoli
- 9 Institute of Genetic Medicine, John Walton Muscular Dystrophy Research Centre, MRC Centre for Neuromuscular Diseases, Newcastle University, Newcastle upon Tyne, NE1 3BZ, UK
| | - Matthew Pitt
- 11 Department of Clinical Neurophysiology, Great Ormond Street Hospital for children NHS foundation trust, London WC1N 3JH
| | - Robin Kennett
- 2 Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, Oxford, OX3 9DU, UK
| | - Andrew Schaefer
- 5 Department of Neurology, Royal Victoria Infirmary, Newcastle upon Tyne, NE1 4LP, UK
| | - Kate Bushby
- 9 Institute of Genetic Medicine, John Walton Muscular Dystrophy Research Centre, MRC Centre for Neuromuscular Diseases, Newcastle University, Newcastle upon Tyne, NE1 3BZ, UK
| | - Matt Parton
- 10 MRC Centre for Neuromuscular Diseases, UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery, Queen Square, London, UK
| | - Hanns Lochmüller
- 9 Institute of Genetic Medicine, John Walton Muscular Dystrophy Research Centre, MRC Centre for Neuromuscular Diseases, Newcastle University, Newcastle upon Tyne, NE1 3BZ, UK
| | - Jacqueline Palace
- 2 Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, Oxford, OX3 9DU, UK
| | - Francesco Muntoni
- 12 Dubowitz Neuromuscular Centre and MRC Centre for Neuromuscular Diseases, UCL Institute of Child Health, London, WC1N 1EH, UK
| | - David Beeson
- 1 Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, OX3 9DS, UK
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Engel AG, Shen XM, Selcen D, Sine SM. Congenital myasthenic syndromes: pathogenesis, diagnosis, and treatment. Lancet Neurol 2015; 14:420-34. [PMID: 25792100 PMCID: PMC4520251 DOI: 10.1016/s1474-4422(14)70201-7] [Citation(s) in RCA: 336] [Impact Index Per Article: 37.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The congenital myasthenic syndromes (CMS) are a diverse group of genetic disorders caused by abnormal signal transmission at the motor endplate, a special synaptic contact between motor axons and each skeletal muscle fibre. Most CMS stem from molecular defects in the muscle nicotinic acetylcholine receptor, but they can also be caused by mutations in presynaptic proteins, mutations in proteins associated with the synaptic basal lamina, defects in endplate development and maintenance, or defects in protein glycosylation. The specific diagnosis of some CMS can sometimes be reached by phenotypic clues pointing to the mutated gene. In the absence of such clues, exome sequencing is a useful technique for finding the disease gene. Greater understanding of the mechanisms of CMS have been obtained from structural and electrophysiological studies of the endplate, and from biochemical studies. Present therapies for the CMS include cholinergic agonists, long-lived open-channel blockers of the acetylcholine receptor ion channel, and adrenergic agonists. Although most CMS are treatable, caution should be exercised as some drugs that are beneficial in one syndrome can be detrimental in another.
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Affiliation(s)
- Andrew G Engel
- Department of Neurology, Mayo Clinic, Rochester, MN, USA.
| | - Xin-Ming Shen
- Department of Neurology, Mayo Clinic, Rochester, MN, USA
| | - Duygu Selcen
- Department of Neurology, Mayo Clinic, Rochester, MN, USA
| | - Steven M Sine
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN, USA
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Zhu H, Grajales-Reyes GE, Alicea-Vázquez V, Grajales-Reyes JG, Robinson K, Pytel P, Báez-Pagán CA, Lasalde-Dominicci JA, Gomez CM. Fluoxetine is neuroprotective in slow-channel congenital myasthenic syndrome. Exp Neurol 2014; 270:88-94. [PMID: 25448156 DOI: 10.1016/j.expneurol.2014.10.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Revised: 09/30/2014] [Accepted: 10/17/2014] [Indexed: 11/19/2022]
Abstract
The slow-channel congenital myasthenic syndrome (SCS) is an inherited neurodegenerative disease that caused mutations in the acetylcholine receptor (AChR) affecting neuromuscular transmission. Leaky AChRs lead to Ca(2+) overload and degeneration of the neuromuscular junction (NMJ) attributed to activation of cysteine proteases and apoptotic changes of synaptic nuclei. Here we use transgenic mouse models expressing two different mutations found in SCS to demonstrate that inhibition of prolonged opening of mutant AChRs using fluoxetine not only improves motor performance and neuromuscular transmission but also prevents Ca(2+) overload, the activation of cysteine proteases, calpain, caspase-3 and 9 at endplates, and as a consequence, reduces subsynaptic DNA damage at endplates, suggesting a long term benefit to therapy. These studies suggest that prolonged treatment of SCS patients with open ion channel blockers that preferentially block mutant AChRs is neuroprotective.
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Affiliation(s)
- Haipeng Zhu
- Department of Neurology, The University of Chicago, Chicago, IL, USA
| | | | | | | | - KaReisha Robinson
- Department of Neurology, The University of Chicago, Chicago, IL, USA
| | - Peter Pytel
- Department of Pathology, The University of Chicago, Chicago, IL, USA
| | - Carlos A Báez-Pagán
- Department of Biology, The University of Puerto Rico, San Juan, Puerto Rico, USA
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44
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Inherited disorders of the neuromuscular junction: an update. J Neurol 2014; 261:2234-43. [PMID: 25305004 DOI: 10.1007/s00415-014-7520-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Accepted: 09/23/2014] [Indexed: 10/24/2022]
Abstract
Congenital myasthenic syndromes (CMSs) are a group of heterogeneous inherited disorders caused by mutations in genes affecting the function and structure of the neuromuscular junction. This review updates the reader on established and novel subtypes of congenital myasthenia, and the treatment strategies for these increasingly heterogeneous disorders. The discovery of mutations associated with the N-glycosylation pathway and in the family of serine peptidases has shown that causative genes encoding ubiquitously expressed molecules can produce defects at the human neuromuscular junction. By contrast, mutations in lipoprotein-like receptor 4 (LRP4), a long-time candidate gene for congenital myasthenia, and a novel phenotype of myasthenia with distal weakness and atrophy due to mutations in AGRN have now been described. In addition, a pathogenic splicing mutation in a nonfunctional exon of CHRNA1 has been reported emphasizing the importance of analysing nonfunctional exons in genetic analysis. The benefit of salbutamol and ephedrine alone or combined with pyridostigmine or 3,4-DAP is increasingly being reported for particular subtypes of CMS.
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Abstract
OPINION STATEMENT Neuromuscular channelopathies are heterogeneous disorders with marked phenotypic and genotypic variability. These include non-dystrophic myotonia (NDM), periodic paralysis (PP), and congenital myasthenic syndrome (CMS). Their diverse clinical manifestations remain a challenge in diagnosis and management to this date. These disorders impact quality of life and cause lifelong disabling symptoms. Treatment options are few and not FDA-approved. This is largely due to a paucity of large, randomized clinical trials in these rare diseases. Challenges of conducting such trials include the rarity of these disorders and the genetic heterogeneity. Physicians rely on off-label use of drugs to treat muscle channelopathies to reduce morbidity and improve quality of life. Besides pharmacological treatment, dietary modifications, lifestyle changes, awareness of triggers, and genetic counseling also play an important role in long-term disease management. This article reviews the current management strategies for neuromuscular channelopathies.
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46
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Eymard B, Stojkovic T, Sternberg D, Richard P, Nicole S, Fournier E, Béhin A, Laforêt P, Servais L, Romero N, Fardeau M, Hantaï D. [Congenital myasthenic syndromes: difficulties in the diagnosis, course and prognosis, and therapy--The French National Congenital Myasthenic Syndrome Network experience]. Rev Neurol (Paris) 2013; 169 Suppl 1:S45-55. [PMID: 23452772 DOI: 10.1016/s0035-3787(13)70060-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Congenital myasthenic syndromes (CMS) are a heterogeneous group of disorders caused by genetic defects affecting neuromuscular transmission and leading to muscle weakness accentuated by exertion. Three different aspects have been investigated by members of the national French CMS Network: the difficulties in making a proper diagnosis; the course and long-term prognosis; and the response to therapy, especially for CMS that do not respond to cholinesterase inhibitors. CMS diagnosis is late in most cases because of confusion with other entities such as: congenital myopathies, due to the frequent presentation in patients of myopathies such as permanent muscle weakness, atrophy and scoliosis, and the abnormalities of internal structure, diameter and distribution of fibers (type I predominance, type II atrophy) seen on biopsy; seronegative autoimmune myasthenia gravis, when CMS is of late onset; and metabolic myopathy, with the presence of lipidosis in muscle. The long-term prognosis of CMS was studied in a series of 79 patients recruited with the following gene mutations: CHRNA; CHRNE; DOK7; COLQ; RAPSN; AGRN; and MUSK. Disease-course patterns (progressive worsening, exacerbation, stability, improvement) could be variable throughout life in a given patient. DOK7 patients had the most severe disease course with progressive worsening: of the eight wheelchair-bound and ventilated patients, six had mutations of this gene. Pregnancy was a frequent cause of exacerbation. Anticholinesterase agents are the first-line therapy for CMS patients, except for cases of slow-channel CMS, COLQ and DOK7. In our experience, 3,4-DAP was a useful complement for several patients harboring CMS with AChR loss or RAPSN gene mutations. Ephedrine was given to 18 patients (eight DOK7, five COLQ, four AGRN and one RAPSN). Tolerability was good. Therapeutic responses were encouraging even in the most severely affected patients, particularly with DOK7 and COLQ. Salbutamol was a good alternative in one patient who was allergic to ephedrine.
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Affiliation(s)
- B Eymard
- Centre de référence des affections neuromusculaires Paris-Est, service de Neurologie 2, Institut de Myologie, Hôpital de la Pitié-Salpêtrière, 47 bd de l'Hôpital, 75013 Paris, France.
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Peyer AK, Abicht A, Heinimann K, Sinnreich M, Fischer D. Quinine sulfate as a therapeutic option in a patient with slow channel congenital myasthenic syndrome. Neuromuscul Disord 2013; 23:571-4. [PMID: 23688972 DOI: 10.1016/j.nmd.2013.04.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2012] [Revised: 03/28/2013] [Accepted: 04/08/2013] [Indexed: 10/26/2022]
Abstract
Slow channel congenital myasthenic syndrome is caused by a genetically determined kinetic anomaly of the acetylcholine receptor at the neuromuscular junction leading to its prolonged open state. Patients typically present with fatigability and static weakness of neck, hand and finger extensors. The open-channel blockers fluoxetine and quinidine have been used as standard treatment, although the former is limited by its side effects. We describe a patient with a novel "de novo" mutation in the α subunit of acetylcholine receptor with clinical and electrophysiological hallmarks of the disease. The patient showed marked treatment response to fluoxetine as well as quinine, a stereoisomer of quinidine, expanding the treatment options for this hereditary disorder.
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Affiliation(s)
- Anne-Kathrin Peyer
- Department of Neurology and Biomedicine, University Hospital Basel, CH, Switzerland.
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Patel JC, Barvaliya MJ, Patel TK, Tripathi CB. Neuromuscular blocking effect of fluoxetine and its interaction with rocuronium. ACTA ACUST UNITED AC 2013; 33:17-24. [PMID: 23461555 DOI: 10.1111/aap.12005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2012] [Revised: 08/18/2012] [Accepted: 09/25/2012] [Indexed: 11/29/2022]
Abstract
As selective serotonin reuptake inhibitors have an inhibitory effect on nicotinic acetylcholine receptors, they may affect the neuromuscular transmission and interact with neuromuscular blockers. This study was designed to observe the effect of fluoxetine on neuromuscular transmission and its interaction with rocuronium using the rat phrenic nerve hemidiaphragm and rabbit head drop methods. Rat phrenic nerve hemidiaphragms were mounted and stimulated using a train of four pulses (TOF). The effect of fluoxetine was studied on both indirectly and directly stimulated basal twitch responses by plotting cumulative dose response curves (DRCs). DRCs of rocuronium were obtained in the absence, and presence of 5 μm and 20 μm fluoxetine to study its interaction. ED5 , ED50 and ED95 values of rocuronium DRCs in absence and presence of fluoxetine were calculated. Fluoxetine significantly inhibited twitch responses in both indirect and directly stimulated preparations. Fluoxetine (20 μm) caused an increase in the potency of rocuronium such that the ED50 and ED95 values of rocuronium DRCs were significantly decreased. Partially inhibited twitch responses by fluoxetine (100 μm) were not reversed by neostigmine (3.3 μm) or 3,4 diaminopyridine (0.25 μm). Rabbits were given fluoxetine 0.25 mg kg(-1) and 1 mg kg(-1) orally for 15 days, and on 15th day, rocuronium infusion was given, and time for head drop was recorded. The time of head drop was significantly reduced in fluoxetine pretreated as compared to control group. Fluoxetine blocks the neuromuscular transmission and increases the potency of rocuronium-induced neuromuscular block.
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Affiliation(s)
- J C Patel
- Department of Pharmacology, Government Medical College, Bhavanagar, 364001, Gujarat, India
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Abicht A, Dusl M, Gallenmüller C, Guergueltcheva V, Schara U, Della Marina A, Wibbeler E, Almaras S, Mihaylova V, von der Hagen M, Huebner A, Chaouch A, Müller JS, Lochmüller H. Congenital myasthenic syndromes: Achievements and limitations of phenotype-guided gene-after-gene sequencing in diagnostic practice: A study of 680 patients. Hum Mutat 2012; 33:1474-84. [DOI: 10.1002/humu.22130] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2011] [Accepted: 04/30/2012] [Indexed: 11/09/2022]
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Lorenzoni PJ, Scola RH, Kay CSK, Werneck LC. Congenital myasthenic syndrome: a brief review. Pediatr Neurol 2012; 46:141-8. [PMID: 22353287 DOI: 10.1016/j.pediatrneurol.2011.12.001] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2011] [Accepted: 12/22/2011] [Indexed: 01/04/2023]
Abstract
Congenital myasthenic syndromes comprise heterogeneous genetic diseases characterized by compromised neuromuscular transmission. Congenital myasthenic syndromes are classified as presynaptic, synaptic, or postsynaptic, depending on the primary defect's location within the neuromuscular junction. Presynaptic forms are the rarest, affecting an estimated 7-8% of patients; synaptic forms account for approximately 14-15% of patients; and the remaining 75-80% are attributable to postsynaptic defects. Clinical manifestations vary by congenital myasthenic syndrome subtype. Electrophysiologic, morphologic, and molecular descriptions of various forms of congenital myasthenic syndromes have led to an enhanced understanding of clinical manifestations and disease pathophysiology. Although congenital myasthenic syndromes are indicated by clinical manifestations, family history, electrophysiologic studies, and responses to acetylcholinesterase inhibitors, overlap in some presentations occurs. Therefore, genetic testing may be necessary to identify specific mutations in CHAT, COLQ, LAMB2, CHRNA, CHRNB, CHRND, CHRNE, CHRNG, RAPSN, DOK7, MUSK, AGRN, SCN4A, GFPT1, or PLEC1 genes. The identification of congenital myasthenic syndromes subtypes will prove important in the treatment of these patients. Different drugs may be beneficial, or should be avoided because they are ineffective or worsen some forms of congenital myasthenic syndromes. We explore the classification, clinical manifestations, electrophysiologic features, genetics, and treatment responses of each congenital myasthenic syndrome subtype.
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Affiliation(s)
- Paulo José Lorenzoni
- Neuromuscular Disorders Unit, Division of Neurology, Department of Internal Medicine, Hospital de Clínicas da Universidade Federal do Paraná, Curitiba, PR, Brazil
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