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Smeets N, Gheldof A, Dequeker B, Poleur M, Maldonado Slootjes S, Van Parijs V, Deconinck N, Dontaine P, Alonso-Jimenez A, De Bleecker J, De Ridder W, Herdewyn S, Paquay S, Vanlander A, De Waele L, Peirens G, Beysen D, Claeys KG, Dubuisson N, Hansen I, Remiche G, Seneca S, Bissay V, Régal L. Congenital Myasthenic Syndromes in Belgium: Genetic and Clinical Characterization of Pediatric and Adult Patients. Pediatr Neurol 2024; 158:57-65. [PMID: 38964204 DOI: 10.1016/j.pediatrneurol.2024.06.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/10/2024] [Revised: 05/29/2024] [Accepted: 06/05/2024] [Indexed: 07/06/2024]
Abstract
BACKGROUND Congenital myasthenic syndromes (CMS) are a group of genetic disorders characterized by impaired neuromuscular transmission. CMS typically present at a young age with fatigable muscle weakness, often with an abnormal response after repetitive nerve stimulation (RNS). Pharmacologic treatment can improve symptoms, depending on the underlying defect. Prevalence is likely underestimated. This study reports on patients with CMS followed in Belgium in 2022. METHODS Data were gathered retrospectively from the medical charts. Only likely pathogenic and pathogenic variants were included in the analysis. RESULTS We identified 37 patients, resulting in an estimated prevalence of 3.19 per 1,000,000. The patients harbored pathogenic variants in CHRNE, RAPSN, DOK7, PREPL, CHRNB1, CHRNG, COLQ, MUSK, CHRND, GFPT1, and GMPPB. CHRNE was the most commonly affected gene. Most patients showed disease onset at birth, during infancy, or during childhood. Symptom onset was at adult age in seven patients, caused by variants in CHRNE, DOK7, MUSK, CHRND, and GMPPB. Severity and distribution of weakness varied, as did the presence of respiratory involvement, feeding problems, and extraneuromuscular manifestations. RNS was performed in 23 patients of whom 18 demonstrated a pathologic decrement. Most treatment responses were predictable based on the genotype. CONCLUSIONS This is the first pooled characterization of patients with CMS in Belgium. We broaden the phenotypical spectrum of pathogenic variants in CHRNE with adult-onset CMS. Systematically documenting larger cohorts of patients with CMS can aid in better clinical characterization and earlier recognition of this rare disease. We emphasize the importance of establishing a molecular genetic diagnosis to tailor treatment choices.
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Affiliation(s)
- Nathalie Smeets
- Child Neurology Unit, Department of Pediatrics, Vrije Universiteit Brussel, Universitair Ziekenhuis Brussel, Brussels, Belgium.
| | - Alexander Gheldof
- Center of Medical Genetics, Vrije Universiteit Brussel, Universitair Ziekenhuis Brussel, Brussels, Belgium
| | - Bart Dequeker
- Center of Medical Genetics, Vrije Universiteit Brussel, Universitair Ziekenhuis Brussel, Brussels, Belgium
| | - Margaux Poleur
- University Department of Neurology, Citadelle Hospital of Liège, Liège, Belgium
| | | | - Vinciane Van Parijs
- Department of Neurology, Cliniques Universitaires Saint-Luc, Brussels, Belgium
| | - Nicolas Deconinck
- Department of Pediatric Neurology, Queen Fabiola Children's University Hospital, Université Libre De Bruxelles, Brussels, Belgium
| | - Pauline Dontaine
- Department of Pediatric Neurology, Queen Fabiola Children's University Hospital, Université Libre De Bruxelles, Brussels, Belgium
| | - Alicia Alonso-Jimenez
- Department of Neurology, University of Antwerp, Antwerp University Hospital, Antwerp, Belgium
| | - Jan De Bleecker
- Department of Neurology, Ghent University Hospital, Ghent, Belgium
| | - Willem De Ridder
- Department of Neurology, University of Antwerp, Antwerp University Hospital, Antwerp, Belgium
| | - Sarah Herdewyn
- Department of Neurology, Ghent University Hospital, Ghent, Belgium
| | - Stéphanie Paquay
- Department of Neuropediatrics, Cliniques Universitaires Saint-Luc, Brussels, Belgium
| | - Arnaud Vanlander
- Department of Pediatric Neurology and Metabolic Diseases, Ghent University Hospital, Ghent, Belgium
| | - Liesbeth De Waele
- Department of Development and Regeneration, KU Leuven, Leuven, Belgium; Department of Pediatric Neurology, University Hospitals Leuven, Leuven, Belgium
| | - Geertrui Peirens
- Department of Development and Regeneration, KU Leuven, Leuven, Belgium; Department of Pediatric Neurology, University Hospitals Leuven, Leuven, Belgium
| | - Diane Beysen
- Department of Pediatric Neurology, University of Antwerp, Antwerp University Hospital, Antwerp, Belgium
| | - Kristl G Claeys
- Department of Neurology, University Hospitals Leuven, Leuven, Belgium; Laboratory for Muscle Diseases and Neuropathies, Department of Neurosciences, KU Leuven, Leuven Brain Institute (LBI), Leuven, Belgium
| | - Nicolas Dubuisson
- Department of Neurology, Cliniques Universitaires Saint-Luc, Brussels, Belgium
| | - Isabelle Hansen
- Department of Neurology, University of Liège, Centre Hospitalier Universitaire de Liège, Liège, Belgium
| | - Gauthier Remiche
- Department of Neurology, Hôpital Universitaire de Bruxelles - Hôpital Erasme, Université Libre de Bruxelles, Brussels, Belgium
| | - Sara Seneca
- Center of Medical Genetics, Vrije Universiteit Brussel, Universitair Ziekenhuis Brussel, Brussels, Belgium
| | - Véronique Bissay
- NEUR Research Group and Department of Neurology, Vrije Universiteit Brussel, Universitair Ziekenhuis Brussel, Brussels, Belgium
| | - Luc Régal
- Child Neurology Unit, Department of Pediatrics, Vrije Universiteit Brussel, Universitair Ziekenhuis Brussel, Brussels, Belgium
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Rossi L, Mota BI, Valadão PAC, Magalhães-Gomes MPS, Oliveira BS, Guatimosim S, Navegantes LCC, Miranda AS, Prado MAM, Prado VF, Guatimosim C. INFLUENCE OF β 2-ADRENERGIC SELECTIVE AGONIST FORMOTEROL ON THE MOTOR UNIT OF A MOUSE MODEL OF A CONGENITAL MYASTHENIC SYNDROME WITH COMPLETE VAChT DELETION. Neuropharmacology 2024:110116. [PMID: 39151654 DOI: 10.1016/j.neuropharm.2024.110116] [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: 05/05/2024] [Revised: 08/09/2024] [Accepted: 08/13/2024] [Indexed: 08/19/2024]
Abstract
Congenital Myasthenic Syndromes (CMS) are a set of genetic diseases that affect the neuromuscular transmission causing muscular weakness. The standard pharmacological treatment aims at ameliorating the myasthenic symptom by acetylcholinesterase inhibitors. Most patients respond well in the short and medium term, however, over time the beneficial effects rapidly fade, and the efficacy of the treatment diminishes. Increasing evidence shows that β2-adrenergic agonists can be a suitable choice for the treatment of neuromuscular disorders, including CMS, as they promote beneficial effects in the neuromuscular system. The exact mechanism on which they rely is not completely understood, although patients and animal models respond well to the treatment, especially over extended periods. Here, we report the use of the long-lasting specific β2-adrenergic agonist formoterol in a myasthenic mouse model (mnVAChT-KD), featuring deletion of VAChT (Vesicular Acetylcholine Transporter) specifically in the α-motoneurons. Our findings demonstrate that formoterol treatment (300 μg/kg/day; sc) for 30 days increased the neuromuscular junction area, induced skeletal muscle hypertrophy and altered fibre type composition in myasthenic mice. Interestingly, β2-adrenergic agonists have shown efficacy even in the absence of ACh (acetylcholine). Our data provide important evidence supporting the potential of β2-adrenergic agonists in treating neuromuscular disorders of pre-synaptic origin and characterized by disruptions in nerve-muscle communication, through a direct and beneficial action within the motor unit.
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Affiliation(s)
- Leonardo Rossi
- Departamento de Morfologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brasil
| | - Bárbara I Mota
- Departamento de Morfologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brasil
| | - Priscila A C Valadão
- Departamento de Morfologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brasil
| | - Matheus P S Magalhães-Gomes
- Departamento de Morfologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brasil; Departamento de Ciências Básicas, Faculdade Ciências Médicas de Minas Gerais, FCMMG, Belo Horizonte, Brasil
| | - Bruna S Oliveira
- Departamento de Morfologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brasil
| | - Silvia Guatimosim
- Departamento de Fisiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brasil
| | - Luiz C C Navegantes
- Departamento de Fisiologia, Escola de Medicina, Universidade de São Paulo, Ribeirão Preto, São Paulo, Brasil
| | - Aline S Miranda
- Departamento de Morfologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brasil
| | - Marco A M Prado
- Robarts Research Institute, Schulich School of Medicine & Dentistry, University of Western Ontario, London, Canada; Department of Anatomy and Cell Biology, Schulich School of Medicine & Dentistry, University of Western Ontario, London, Canada; Department of Physiology and Pharmacology, Schulich School of Medicine & Dentistry, University of Western Ontario, London, Canada; Brain and Mind Institute, University of Western Ontario, London, Canada
| | - Vânia F Prado
- Robarts Research Institute, Schulich School of Medicine & Dentistry, University of Western Ontario, London, Canada; Department of Anatomy and Cell Biology, Schulich School of Medicine & Dentistry, University of Western Ontario, London, Canada; Department of Physiology and Pharmacology, Schulich School of Medicine & Dentistry, University of Western Ontario, London, Canada; Brain and Mind Institute, University of Western Ontario, London, Canada
| | - Cristina Guatimosim
- Departamento de Morfologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brasil.
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3
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Muntadas JA, Hyland MR, Martínez MDRO, Young JN, Chong JX, Bamshad MJ, Maselli RA. Congenital myasthenic syndrome secondary to pathogenic variants in the SLC5A7 gene: report of two cases. BMC Med Genomics 2024; 17:207. [PMID: 39135055 PMCID: PMC11318227 DOI: 10.1186/s12920-024-01977-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2024] [Accepted: 07/31/2024] [Indexed: 08/16/2024] Open
Abstract
BACKGROUND Congenital Myasthenic Syndromes (CMS) are rare genetic diseases, which share as a common denominator muscle fatigability due to failure of neuromuscular transmission. A distinctive clinical feature of presynaptic CMS variants caused by defects of the synthesis of acetylcholine is the association with life-threatening episodes of apnea. One of these variants is caused by mutations in the SLC5A7 gene, which encodes the sodium-dependent HC-3 high-affinity choline transporter 1 (CHT1). To our knowledge there are no published cases of this CMS type in Latin America. CASE PRESENTATION We present two cases of CHT1-CMS. Both patients were males presenting with repeated episodes of apnea, hypotonia, weakness, ptosis, mild ophthalmoparesis, and bulbar deficit. The first case also presented one isolated seizure, while the second case showed global developmental delay. Both cases, exhibited incomplete improvement with treatment with pyridostigmine. CONCLUSIONS This report emphasizes the broad incidence of CMS with episodic apnea caused by mutations in the SLC5A7 gene and the frequent association of this condition with serious manifestations of central nervous system involvement.
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Affiliation(s)
- Javier A Muntadas
- Pediatric Neurology, Hospital Italiano, Gascon 450. Capital Federal, Buenos Aires, 4959-0200, Argentina
| | - Martin R Hyland
- Pediatric Neurology, Hospital Italiano, Gascon 450. Capital Federal, Buenos Aires, 4959-0200, Argentina
| | | | - Jaime N Young
- Department of Neurology, University of California Davis, 1515 Newton Court, Davis, CA, 95618, USA
| | - Jessica X Chong
- Brotman Baty Institute for Precision Medicine, 1959 NE Pacific St, Seattle, WA, 98195, USA
- Division of Genetic Medicine, Department of Pediatrics, University of Washington, 4245 Roosevelt Way NE, Seattle, WA, 98105, USA
| | - Michael J Bamshad
- Department of Genome Sciences, University of Washington, William H. Foege Hall, 3720 15th Ave NE, Seattle, WA, 98195, USA
- Brotman Baty Institute for Precision Medicine, 1959 NE Pacific St, Seattle, WA, 98195, USA
- Division of Genetic Medicine, Department of Pediatrics, University of Washington, 4245 Roosevelt Way NE, Seattle, WA, 98105, USA
| | - Ricardo A Maselli
- Department of Neurology, University of California Davis, 1515 Newton Court, Davis, CA, 95618, USA.
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De Cicco T, Pęziński M, Wójcicka O, Pradhan BS, Jabłońska M, Rottner K, Prószyński TJ. Cortactin interacts with αDystrobrevin-1 and regulates murine neuromuscular junction morphology. Eur J Cell Biol 2024; 103:151409. [PMID: 38579603 DOI: 10.1016/j.ejcb.2024.151409] [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: 12/31/2023] [Revised: 03/24/2024] [Accepted: 03/29/2024] [Indexed: 04/07/2024] Open
Abstract
Neuromuscular junctions transmit signals from the nervous system to skeletal muscles, triggering their contraction, and their proper organization is essential for breathing and voluntary movements. αDystrobrevin-1 is a cytoplasmic component of the dystrophin-glycoprotein complex and has pivotal functions in regulating the integrity of muscle fibers and neuromuscular junctions. Previous studies identified that αDystrobrevin-1 functions in the organization of the neuromuscular junction and that its phosphorylation in the C-terminus is required in this process. Our proteomic screen identified several putative αDystrobrevin-1 interactors recruited to the Y730 site in phosphorylated and unphosphorylated states. Amongst various actin-modulating proteins, we identified the Arp2/3 complex regulator cortactin. We showed that similarly to αDystrobrevin-1, cortactin is strongly enriched at the neuromuscular postsynaptic machinery and obtained results suggesting that these two proteins interact in cell homogenates and at the neuromuscular junctions. Analysis of synaptic morphology in cortactin knockout mice showed abnormalities in the slow-twitching soleus muscle and not in the fast-twitching tibialis anterior. However, muscle strength examination did not reveal apparent deficits in knockout animals.
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Affiliation(s)
- Teresa De Cicco
- Łukasiewicz Research Network - PORT Polish Center for Technology Development, Stabłowicka 147, Wrocław 54-066, Poland; Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur Street, Warsaw 02-093, Poland
| | - Marcin Pęziński
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur Street, Warsaw 02-093, Poland
| | - Olga Wójcicka
- Łukasiewicz Research Network - PORT Polish Center for Technology Development, Stabłowicka 147, Wrocław 54-066, Poland
| | - Bhola Shankar Pradhan
- Łukasiewicz Research Network - PORT Polish Center for Technology Development, Stabłowicka 147, Wrocław 54-066, Poland
| | - Margareta Jabłońska
- Łukasiewicz Research Network - PORT Polish Center for Technology Development, Stabłowicka 147, Wrocław 54-066, Poland
| | - Klemens Rottner
- Division of Molecular Cell Biology, Zoological Institute, Technische Universität Braunschweig, Germany; Department of Cell Biology, Helmholtz Centre for Infection Research, Inhoffenstraße 7, Braunschweig 38124, Germany
| | - Tomasz J Prószyński
- Łukasiewicz Research Network - PORT Polish Center for Technology Development, Stabłowicka 147, Wrocław 54-066, Poland; Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur Street, Warsaw 02-093, Poland.
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5
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McLean A, Wilson I. Congenital myasthenic syndrome from a MUSK gene mutation. Pract Neurol 2024; 24:238-240. [PMID: 37985124 DOI: 10.1136/pn-2023-003945] [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] [Accepted: 10/31/2023] [Indexed: 11/22/2023]
Abstract
Slowly progressive neuromuscular symptoms often have a genetic basis. We present the case of a woman in her 40s with gradually progressive symmetrical weakness and respiratory muscle involvement. Extensive investigation found no specific cause. After a novel neuromuscular gene panel became available, we identified a mutation in the MUSK gene (muscle-specific kinase), confirming a diagnosis of congenital myasthenic syndrome. This group of rare disorders are caused by mutations in genes encoding the neuromuscular junction.
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Affiliation(s)
- Antonia McLean
- Neurology, Cairns Hospital, Cairns, Queensland, Australia
| | - Ian Wilson
- Neurology, Cairns Hospital, Cairns, Queensland, Australia
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6
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Henehan L, Beeson D, Palace J. Congenital myasthenic syndromes. Pract Neurol 2024; 24:185-187. [PMID: 38631903 DOI: 10.1136/pn-2024-004098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/01/2024] [Indexed: 04/19/2024]
Affiliation(s)
- Leighann Henehan
- Department of Clinical Neurology, John Radcliffe Hospital, Oxford, Oxfordshire, UK
| | - David Beeson
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Jacqueline Palace
- Department of Clinical Neurology, John Radcliffe Hospital, Oxford, Oxfordshire, UK
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7
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Zambon AA, Falzone YM, Bolino A, Previtali SC. Molecular mechanisms and therapeutic strategies for neuromuscular diseases. Cell Mol Life Sci 2024; 81:198. [PMID: 38678519 PMCID: PMC11056344 DOI: 10.1007/s00018-024-05229-9] [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: 01/02/2024] [Revised: 03/14/2024] [Accepted: 04/07/2024] [Indexed: 05/01/2024]
Abstract
Neuromuscular diseases encompass a heterogeneous array of disorders characterized by varying onset ages, clinical presentations, severity, and progression. While these conditions can stem from acquired or inherited causes, this review specifically focuses on disorders arising from genetic abnormalities, excluding metabolic conditions. The pathogenic defect may primarily affect the anterior horn cells, the axonal or myelin component of peripheral nerves, the neuromuscular junction, or skeletal and/or cardiac muscles. While inherited neuromuscular disorders have been historically deemed not treatable, the advent of gene-based and molecular therapies is reshaping the treatment landscape for this group of condition. With the caveat that many products still fail to translate the positive results obtained in pre-clinical models to humans, both the technological development (e.g., implementation of tissue-specific vectors) as well as advances on the knowledge of pathogenetic mechanisms form a collective foundation for potentially curative approaches to these debilitating conditions. This review delineates the current panorama of therapies targeting the most prevalent forms of inherited neuromuscular diseases, emphasizing approved treatments and those already undergoing human testing, offering insights into the state-of-the-art interventions.
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Affiliation(s)
- Alberto Andrea Zambon
- Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Institute for Experimental Neurology, Inspe, Milan, Italy
- Neurology Department, San Raffaele Scientific Institute, Milan, Italy
- Vita-Salute San Raffaele University, Milan, Italy
| | - Yuri Matteo Falzone
- Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Institute for Experimental Neurology, Inspe, Milan, Italy
- Neurology Department, San Raffaele Scientific Institute, Milan, Italy
| | - Alessandra Bolino
- Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Institute for Experimental Neurology, Inspe, Milan, Italy
- Vita-Salute San Raffaele University, Milan, Italy
| | - Stefano Carlo Previtali
- Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Institute for Experimental Neurology, Inspe, Milan, Italy.
- Neurology Department, San Raffaele Scientific Institute, Milan, Italy.
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8
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Han JY, Park J. Novel compound heterozygous mutations in SCN4A as a potential genetic cause contributing to myopathic manifestations: A case report and literature review. Heliyon 2024; 10:e28684. [PMID: 38571618 PMCID: PMC10988054 DOI: 10.1016/j.heliyon.2024.e28684] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Revised: 03/13/2024] [Accepted: 03/22/2024] [Indexed: 04/05/2024] Open
Abstract
Background SCN4A mutations account for a diverse array of clinical manifestations, encompassing periodic paralysis, myotonia, and newly recognized symptoms like classical congenital myopathy or congenital myasthenic syndromes. We describe the initial occurrence of myopathic features mimic with recessive classical CM in a Korean infant presenting with novel compound heterozygous SCN4A mutations. The infant exhibited profound hypotonia after birth, thereby expanding the spectrum of SCN4A-related channelopathy. Methods The genetic analyses comprised targeted exome sequencing, employing a Celemics G-Mendeliome DES Panel, along with Sanger sequencing. Results Considering the clinical manifestations observed in the proband, SCN4A variants emerged as the primary contenders for autosomal recessive (AR) congenital myopathy 22a, classic (#620351). Sanger sequencing validated the association of SCN4A variants with the phenotype, affirming the AR nature of the compound heterozygous variants in both the carrier mother (c.3533G > T/p.Gly1178Val) and the father (c.4216G > A/p.Ala1406Thr). Conclusion Our report emphasizes the association of novel compound heterozygous mutations in SCN4A with myopathic features resembling CM, as supporting by muscle biopsy. It is essential to note that pathogenic SCN4A LoF mutations are exceedingly rare. This study contributes to our understanding of SCN4A mutations and their role in myopathic features mimic with classical CM.
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Affiliation(s)
- Ji Yoon Han
- Department of Pediatrics, College of Medicine, The Catholic University of Korea, Seoul, 06591, Republic of Korea
| | - Joonhong Park
- Department of Laboratory Medicine, Jeonbuk National University Medical School and Hospital, Jeonju, 54907, Republic of Korea
- Research Institute of Clinical Medicine of Jeonbuk National University-Biomedical Research Institute of Jeonbuk National University Hospital, Jeonju, 54907, Republic of Korea
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9
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Polavarapu K, Sunitha B, Töpf A, Preethish-Kumar V, Thompson R, Vengalil S, Nashi S, Bardhan M, Sanka SB, Huddar A, Unnikrishnan G, Arunachal G, Girija MS, Porter A, Azuma Y, Lorenzoni PJ, Baskar D, Anjanappa RM, Keertipriya M, Padmanabh H, Harikrishna GV, Laurie S, Matalonga L, Horvath R, Nalini A, Lochmüller H. Clinical and genetic characterisation of a large Indian congenital myasthenic syndrome cohort. Brain 2024; 147:281-296. [PMID: 37721175 PMCID: PMC10766255 DOI: 10.1093/brain/awad315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Revised: 06/20/2023] [Accepted: 08/10/2023] [Indexed: 09/19/2023] Open
Abstract
Congenital myasthenic syndromes (CMS) are a rare group of inherited disorders caused by gene defects associated with the neuromuscular junction and potentially treatable with commonly available medications such as acetylcholinesterase inhibitors and β2 adrenergic receptor agonists. In this study, we identified and genetically characterized the largest cohort of CMS patients from India to date. Genetic testing of clinically suspected patients evaluated in a South Indian hospital during the period 2014-19 was carried out by standard diagnostic gene panel testing or using a two-step method that included hotspot screening followed by whole-exome sequencing. In total, 156 genetically diagnosed patients (141 families) were characterized and the mutational spectrum and genotype-phenotype correlation described. Overall, 87 males and 69 females were evaluated, with the age of onset ranging from congenital to fourth decade (mean 6.6 ± 9.8 years). The mean age at diagnosis was 19 ± 12.8 (1-56 years), with a mean diagnostic delay of 12.5 ± 9.9 (0-49 years). Disease-causing variants in 17 CMS-associated genes were identified in 132 families (93.6%), while in nine families (6.4%), variants in genes not associated with CMS were found. Overall, postsynaptic defects were most common (62.4%), followed by glycosylation defects (21.3%), synaptic basal lamina genes (4.3%) and presynaptic defects (2.8%). Other genes found to cause neuromuscular junction defects (DES, TEFM) in our cohort accounted for 2.8%. Among the individual CMS genes, the most commonly affected gene was CHRNE (39.4%), followed by DOK7 (14.4%), DPAGT1 (9.8%), GFPT1 (7.6%), MUSK (6.1%), GMPPB (5.3%) and COLQ (4.5%). We identified 22 recurrent variants in this study, out of which eight were found to be geographically specific to the Indian subcontinent. Apart from the known common CHRNE variants p.E443Kfs*64 (11.4%) and DOK7 p.A378Sfs*30 (9.3%), we identified seven novel recurrent variants specific to this cohort, including DPAGT1 p.T380I and DES c.1023+5G>A, for which founder haplotypes are suspected. This study highlights the geographic differences in the frequencies of various causative CMS genes and underlines the increasing significance of glycosylation genes (DPAGT1, GFPT1 and GMPPB) as a cause of neuromuscular junction defects. Myopathy and muscular dystrophy genes such as GMPPB and DES, presenting as gradually progressive limb girdle CMS, expand the phenotypic spectrum. The novel genes MACF1 and TEFM identified in this cohort add to the expanding list of genes with new mechanisms causing neuromuscular junction defects.
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Affiliation(s)
- Kiran Polavarapu
- Department of Neurology, National Institute of Mental Health and Neurosciences, Bangalore 560029, India
- Children’s Hospital of Eastern Ontario Research Institute, Ottawa, ON K1H 8L1, Canada
| | - Balaraju Sunitha
- John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne NE1 3BZ, UK
- Department of Clinical Neurosciences, University of Cambridge School of Clinical Medicine, Cambridge CB2 0SP, UK
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 9DU, UK
| | - Ana Töpf
- John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne NE1 3BZ, UK
| | - Veeramani Preethish-Kumar
- Department of Neurology, National Institute of Mental Health and Neurosciences, Bangalore 560029, India
- Department of Neurology, Neurofoundation, Salem, Tamil Nadu 636009, India
| | - Rachel Thompson
- Children’s Hospital of Eastern Ontario Research Institute, Ottawa, ON K1H 8L1, Canada
| | - Seena Vengalil
- Department of Neurology, National Institute of Mental Health and Neurosciences, Bangalore 560029, India
| | - Saraswati Nashi
- Department of Neurology, National Institute of Mental Health and Neurosciences, Bangalore 560029, India
| | - Mainak Bardhan
- Department of Neurology, National Institute of Mental Health and Neurosciences, Bangalore 560029, India
| | - Sai Bhargava Sanka
- Department of Neurology, National Institute of Mental Health and Neurosciences, Bangalore 560029, India
| | - Akshata Huddar
- Department of Neurology, National Institute of Mental Health and Neurosciences, Bangalore 560029, India
- Department of Neurology, St Johns Medical College Hospital, Bangalore 560034, India
| | - Gopikrishnan Unnikrishnan
- Department of Neurology, National Institute of Mental Health and Neurosciences, Bangalore 560029, India
- Department of Neurology, Amruta Institute of Medical Sciences, Kochi 682041, India
| | - Gautham Arunachal
- Department of Human Genetics, National Institute of Mental Health and Neurosciences, Bengaluru 560029, India
| | - Manu Santhappan Girija
- Department of Neurology, National Institute of Mental Health and Neurosciences, Bangalore 560029, India
| | - Anna Porter
- John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne NE1 3BZ, UK
| | - Yoshiteru Azuma
- John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne NE1 3BZ, UK
| | - Paulo José Lorenzoni
- Neuromuscular Disorders Division, Service of Neurology, Department of Internal Medicine, Hospital de Clínicas, Universidade Federal do Paraná, Rua General Carneiro, Curitiba - PR 80060-900, Brazil
| | - Dipti Baskar
- Department of Neurology, National Institute of Mental Health and Neurosciences, Bangalore 560029, India
| | - Ram Murthy Anjanappa
- Department of Neurology, National Institute of Mental Health and Neurosciences, Bangalore 560029, India
| | - Madassu Keertipriya
- Department of Neurology, National Institute of Mental Health and Neurosciences, Bangalore 560029, India
| | - Hansashree Padmanabh
- Department of Neurology, National Institute of Mental Health and Neurosciences, Bangalore 560029, India
| | | | - Steve Laurie
- Centro Nacional de Análisis Genómico (CNAG-CRG), Center for Genomic Regulation, Barcelona Institute of Science and Technology (BIST), Barcelona, Catalonia 08028, Spain
| | - Leslie Matalonga
- Centro Nacional de Análisis Genómico (CNAG-CRG), Center for Genomic Regulation, Barcelona Institute of Science and Technology (BIST), Barcelona, Catalonia 08028, Spain
| | - Rita Horvath
- Department of Clinical Neurosciences, University of Cambridge School of Clinical Medicine, Cambridge CB2 0SP, UK
| | - Atchayaram Nalini
- Department of Neurology, National Institute of Mental Health and Neurosciences, Bangalore 560029, India
| | - Hanns Lochmüller
- Children’s Hospital of Eastern Ontario Research Institute, Ottawa, ON K1H 8L1, Canada
- Centro Nacional de Análisis Genómico (CNAG-CRG), Center for Genomic Regulation, Barcelona Institute of Science and Technology (BIST), Barcelona, Catalonia 08028, Spain
- Brain and Mind Research Institute, University of Ottawa, Ottawa, ON K1H 8M5, Canada
- Division of Neurology, Department of Medicine, The Ottawa Hospital, Ottawa, ON K1H 8M5, Canada
- Department of Neuropediatrics and Muscle Disorders, Medical Center–University of Freiburg, Faculty of Medicine, Freiburg 79110, Germany
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10
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Yildiz EP, Kilic MA, Yalcin EU, Kurekci F, Avci R, Hacıfazlıoğlu NE, Ceylaner S, Gezdirici A, Çalışkan M. Genetic and clinical evaluation of congenital myasthenic syndromes with long-term follow-up: experience of a tertiary center in Turkey. Acta Neurol Belg 2023; 123:1841-1847. [PMID: 36094697 DOI: 10.1007/s13760-022-02090-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Accepted: 09/01/2022] [Indexed: 11/30/2022]
Abstract
INTRODUCTION Congenital myasthenic syndromes (CMS) are a heterogeneous group of genetic disorders affecting the safety factor which required for neuromuscular transmission. Here we reported our experience in children with CMS. METHODS We retrospectively collected the data of 18 patients with CMS who were examined in our outpatient clinic between January 2021 and January 2022. The diagnosis of CMS was based on the presence of clinical symptoms such as abnormal fatigability and weakness, absence of autoantibodies against acetylcholine receptor and muscle-specific kinase, electromyographic evidence of neuromuscular junction defect, molecular genetic confirmation, and response to treatment. RESULTS The most common mutations were in the acetylcholine receptor (CHRNE) gene (8/18) and choline acetyltransferase (ChAT) (2/18) gene. Despite targeted gene sequencing and whole exome sequencing (WES) were underwent, we couldn't detect a genetic mutation in three out of patients. The most commonly determined initial finding was eyelid ptosis, followed by fatigable weakness, and respiratory insufficiency. Although the most commonly used drug was pyridostigmine, we have experienced that caution should be exercised as it may worsen some types of CMS. DISCUSSION We reported in detail the phenotypic features of very rare gene mutations associated with CMS and our experience in the treatment of this disease. Although CMS are rare genetic disorder, the prognosis can be very promising with appropriate treatment in most CMS subtypes.
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Affiliation(s)
- Edibe Pembegul Yildiz
- Department of Pediatric Neurology, Istanbul Medical Faculty, Istanbul, Turkey.
- Istanbul University Institute of Child Health, Istanbul, Turkey.
- Istanbul University Medical School. Millet Cd, 34000, Fatih-Istanbul, Turkey.
| | - Mehmet Akif Kilic
- Department of Pediatric Neurology, Istanbul Medical Faculty, Istanbul, Turkey
| | - Emek Uyur Yalcin
- Department of Pediatric Neurology, Zeynep Kamil Maternity and Children's Diseases Training and Research Hospital, University of Health Sciences, Istanbul, Turkey
| | - Fulya Kurekci
- Department of Pediatric Neurology, Istanbul Medical Faculty, Istanbul, Turkey
| | - Ridvan Avci
- Department of Pediatric Neurology, Istanbul Medical Faculty, Istanbul, Turkey
| | - Nilüfer Eldeş Hacıfazlıoğlu
- Department of Pediatric Neurology, Zeynep Kamil Maternity and Children's Diseases Training and Research Hospital, University of Health Sciences, Istanbul, Turkey
| | | | - Alper Gezdirici
- Department of Medical Genetics, Basaksehir Cam and Sakura City Hospital, Istanbul, Turkey
| | - Mine Çalışkan
- Department of Pediatric Neurology, Istanbul Medical Faculty, Istanbul, Turkey
- Istanbul University Institute of Child Health, Istanbul, Turkey
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11
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Salih MA. The Meryon Lecture at the 24th annual meeting of the Meryon Society, St. Anne's College, Oxford, UK, 15th July 2022: Neuromuscular diseases in the Arab population. Neuromuscul Disord 2023; 33:792-799. [PMID: 37679229 DOI: 10.1016/j.nmd.2023.08.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/09/2023]
Affiliation(s)
- Mustafa A Salih
- Consultant Pediatric Neurologist, Health Sector, King Abdulaziz City for Science and Technology, Riyadh 11442, Saudi Arabia.
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12
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Muñoz-García MI, Guerrero-Molina MP, de Fuenmayor-Fernández de la Hoz CP, Bermejo-Guerrero L, Arteche-López A, Hernández-Laín A, Martín MA, Domínguez-González C. Delayed Diagnosis of Congenital Myasthenic Syndromes Erroneously Interpreted as Mitochondrial Myopathies. J Clin Med 2023; 12:jcm12093308. [PMID: 37176748 PMCID: PMC10179722 DOI: 10.3390/jcm12093308] [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: 03/11/2023] [Revised: 04/02/2023] [Accepted: 05/04/2023] [Indexed: 05/15/2023] Open
Abstract
BACKGROUND Congenital myasthenic syndromes (CMSs) and primary mitochondrial myopathies (PMMs) can present with ptosis, external ophthalmoplegia, and limb weakness. METHODS Our method involved the description of three cases of CMS that were initially characterized as probable PMM. RESULTS All patients were male and presented with ptosis and/or external ophthalmoplegia at birth, with proximal muscle weakness and fatigue on physical exertion. After normal repetitive nerve stimulation (RNS) studies performed on facial muscles, a muscle biopsy (at a median age of 9) was performed to rule out congenital myopathies. In all three cases, the biopsy findings (COX-negative fibers or respiratory chain defects) pointed to PMM. They were referred to our neuromuscular unit in adulthood to establish a genetic diagnosis. However, at this time, fatigability was evident in the physical exams and RNS in the spinal accessory nerve showed a decremental response in all cases. Targeted genetic studies revealed pathogenic variants in the MUSK, DOK7, and RAPSN genes. The median diagnostic delay was 29 years. Treatment resulted in functional improvement in all cases. CONCLUSIONS Early identification of CMS is essential as medical treatment can provide clear benefits. Its diagnosis can be challenging due to phenotypic overlap with other debilitating disorders. Thus, a high index of suspicion is necessary to guide the diagnostic strategy.
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Affiliation(s)
- Mariana I Muñoz-García
- Neuromuscular Unit, Neurology Department, Hospital Universitario 12 de Octubre, 28041 Madrid, Spain
| | | | | | - Laura Bermejo-Guerrero
- Neuromuscular Unit, Neurology Department, Hospital Universitario 12 de Octubre, 28041 Madrid, Spain
| | - Ana Arteche-López
- Genetics Department, Hospital Universitario 12 de Octubre, 28041 Madrid, Spain
| | | | - Miguel A Martín
- Genetics Department, Hospital Universitario 12 de Octubre, 28041 Madrid, Spain
- Spanish Network for Biomedical Research in Rare Diseases (CIBERER), 28041 Madrid, Spain
- Mitochondrial and Neuromuscular Diseases Research Group, 12 de Octubre, Hospital Research Institute (imas12), 28041 Madrid, Spain
| | - Cristina Domínguez-González
- Neuromuscular Unit, Neurology Department, Hospital Universitario 12 de Octubre, 28041 Madrid, Spain
- Spanish Network for Biomedical Research in Rare Diseases (CIBERER), 28041 Madrid, Spain
- Mitochondrial and Neuromuscular Diseases Research Group, 12 de Octubre, Hospital Research Institute (imas12), 28041 Madrid, Spain
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13
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De Rose DU, Ronci S, Caoci S, Maddaloni C, Diodato D, Catteruccia M, Fattori F, Bosco L, Pro S, Savarese I, Bersani I, Randi F, Trozzi M, Meucci D, Calzolari F, Salvatori G, Solinas A, Dotta A, Campi F. Vocal Cord Paralysis and Feeding Difficulties as Early Diagnostic Clues of Congenital Myasthenic Syndrome with Neonatal Onset: A Case Report and Review of Literature. J Pers Med 2023; 13:jpm13050798. [PMID: 37240968 DOI: 10.3390/jpm13050798] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Revised: 04/21/2023] [Accepted: 05/04/2023] [Indexed: 05/28/2023] Open
Abstract
Herein, we present a newborn female with congenital vocal cord paralysis who required a tracheostomy in the neonatal period. She also presented with feeding difficulties. She was later diagnosed with a clinical picture of congenital myasthenia, associated with three variants of the MUSK gene: the 27-month follow-up was described. In particular, the c.565C>T variant is novel and has never been described in the literature; it causes the insertion of a premature stop codon (p.Arg189Ter) likely leading to a consequent formation of a truncated nonfunctioning protein. We also systematically collected and summarized information on patients' characteristics of previous cases of congenital myasthenia with neonatal onset reported in the literature to date, and we compared them to our case. The literature reported 155 neonatal cases before our case, from 1980 to March 2022. Of 156 neonates with CMS, nine (5.8%) had vocal cord paralysis, whereas 111 (71.2%) had feeding difficulties. Ocular features were evident in 99 infants (63.5%), whereas facial-bulbar symptoms were found in 115 infants (73.7%). In one hundred sixteen infants (74.4%), limbs were involved. Respiratory problems were displayed by 97 infants (62.2%). The combination of congenital stridor, particularly in the presence of an apparently idiopathic bilateral vocal cord paralysis, and poor coordination between sucking and swallowing may indicate an underlying congenital myasthenic syndrome (CMS). Therefore, we suggest testing infants with vocal cord paralysis and feeding difficulties for MUSK and related genes to avoid a late diagnosis of CMS and improve outcomes.
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Affiliation(s)
| | - Sara Ronci
- Neonatal Intensive Care Unit, Bambino Gesù Children's Hospital, IRCCS, 00165 Rome, Italy
| | - Stefano Caoci
- Neonatal Intensive Care Unit, Bambino Gesù Children's Hospital, IRCCS, 00165 Rome, Italy
| | - Chiara Maddaloni
- Neonatal Intensive Care Unit, Bambino Gesù Children's Hospital, IRCCS, 00165 Rome, Italy
| | - Daria Diodato
- Neuromuscular and Neurodegenerative Disorders Unit, Bambino Gesù Children's Hospital, IRCCS, 00165 Rome, Italy
| | - Michela Catteruccia
- Neuromuscular and Neurodegenerative Disorders Unit, Bambino Gesù Children's Hospital, IRCCS, 00165 Rome, Italy
| | - Fabiana Fattori
- Laboratory of Medical Genetics, Translational Cytogenomics Research Unit, Bambino Gesù Children Hospital, IRCCS, 00165 Rome, Italy
| | - Luca Bosco
- Neuromuscular and Neurodegenerative Disorders Unit, Bambino Gesù Children's Hospital, IRCCS, 00165 Rome, Italy
- Department of Science, University Roma Tre, 00146 Rome, Italy
| | - Stefano Pro
- Developmental Neurology Unit, Bambino Gesù Children's Hospital, IRCCS, 00165 Rome, Italy
| | - Immacolata Savarese
- Neonatal Intensive Care Unit, Bambino Gesù Children's Hospital, IRCCS, 00165 Rome, Italy
| | - Iliana Bersani
- Neonatal Intensive Care Unit, Bambino Gesù Children's Hospital, IRCCS, 00165 Rome, Italy
| | - Franco Randi
- Neurosurgery Unit, Bambino Gesù Children's Hospital, IRCCS, 00165 Rome, Italy
| | - Marilena Trozzi
- Airway Surgery Unit, Pediatric Surgery Department, Bambino Gesù Children's Hospital, IRCCS, 00165 Rome, Italy
| | - Duino Meucci
- Airway Surgery Unit, Pediatric Surgery Department, Bambino Gesù Children's Hospital, IRCCS, 00165 Rome, Italy
| | - Flaminia Calzolari
- Neonatal Intensive Care Unit, Bambino Gesù Children's Hospital, IRCCS, 00165 Rome, Italy
| | - Guglielmo Salvatori
- Neonatal Intensive Care Unit, Bambino Gesù Children's Hospital, IRCCS, 00165 Rome, Italy
| | - Agostina Solinas
- Neonatal Intensive Care Unit, Sant'Anna Hospital of Ferrara, 44124 Ferrara, Italy
| | - Andrea Dotta
- Neonatal Intensive Care Unit, Bambino Gesù Children's Hospital, IRCCS, 00165 Rome, Italy
| | - Francesca Campi
- Neonatal Intensive Care Unit, Bambino Gesù Children's Hospital, IRCCS, 00165 Rome, Italy
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14
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Mendpara V, Bethanabotla S, Yadav M, Kanisetti V, Singh G, Das A, Sahu S, Patel H. When Breathing Becomes a Challenge: A Case of Congenital Myasthenia Gravis in an Indian Neonate With a DOK-7 Gene Mutation. Cureus 2023; 15:e38842. [PMID: 37303354 PMCID: PMC10256249 DOI: 10.7759/cureus.38842] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/10/2023] [Indexed: 06/13/2023] Open
Abstract
A rare neuromuscular condition known as congenital myasthenia gravis (CMG) affects some people from birth or very soon after. It results in fatigue and muscle weakness because of genetic abnormalities that interfere with the neuromuscular junction's ability to function, where the nerves and muscles connect. Even among those who have the same genetic mutation, the severity of CMG symptoms might differ considerably. The most typical signs of CMG include eyelid drooping, breathing issues, muscle weakness and weariness, and difficulties swallowing. Clinical examinations, neurophysiologic tests, and genetic analyses are frequently combined to make the diagnosis of CMG. Although there is no known treatment for CMG, many patients may control their symptoms and lead relatively normal lives with the right care. A newborn with CMG due to a DOK-7 gene mutation is described in this article, along with its very early onset. The DOK-7 mutation is a rare variant in the Indian population that causes CMG and usually manifests as 'limb girdle' weakness. However, due to muscle weakness, the neonate in this case developed severe respiratory distress and later died despite rigorous life-saving measures.
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Affiliation(s)
- Vaidehi Mendpara
- Medicine and Surgery, Pediatrics, Government Medical College Surat, Surat, IND
| | | | - Megha Yadav
- Medicine and Surgery, Maharani Laxmi Bai Medical College, Jhansi, IND
| | | | - Gurpreet Singh
- Medicine, Government Medical College and Hospital, Amritsar, IND
| | - Abhirami Das
- Internal Medicine, Rajiv Gandhi Medical College, Thane, IND
| | - Sweta Sahu
- Surgery, Jagadguru Jayadeva Murugarajendra (JJM) Medical College, Davanagere, IND
| | - Hitesh Patel
- Pediatrics and Child Health, Government Medical College and Hospital, Surat, IND
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15
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Rizvi M, Truong TK, Zhou J, Batta M, Moran ES, Pappas J, Chu ML, Caluseriu O, Evrony GD, Leslie EM, Cordat E. Biochemical characterization of two novel mutations in the human high-affinity choline transporter 1 identified in a patient with congenital myasthenic syndrome. Hum Mol Genet 2023; 32:1552-1564. [PMID: 36611016 DOI: 10.1093/hmg/ddac309] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 12/21/2022] [Accepted: 12/22/2022] [Indexed: 01/09/2023] Open
Abstract
Congenital myasthenic syndrome (CMS) is a heterogeneous condition associated with 34 different genes, including SLC5A7, which encodes the high-affinity choline transporter 1 (CHT1). CHT1 is expressed in presynaptic neurons of the neuromuscular junction where it uses the inward sodium gradient to reuptake choline. Biallelic CHT1 mutations often lead to neonatal lethality, and less commonly to non-lethal motor weakness and developmental delays. Here, we report detailed biochemical characterization of two novel mutations in CHT1, p.I294T and p.D349N, which we identified in an 11-year-old patient with a history of neonatal respiratory distress, and subsequent hypotonia and global developmental delay. Heterologous expression of each CHT1 mutant in human embryonic kidney cells showed two different mechanisms of reduced protein function. The p.I294T CHT1 mutant transporter function was detectable, but its abundance and half-life were significantly reduced. In contrast, the p.D349N CHT1 mutant was abundantly expressed at the cell membrane, but transporter function was absent. The residual function of the p.I294T CHT1 mutant may explain the non-lethal form of CMS in this patient, and the divergent mechanisms of reduced CHT1 function that we identified may guide future functional studies of the CHT1 myasthenic syndrome. Based on these in vitro studies that provided a diagnosis, treatment with cholinesterase inhibitor together with physical and occupational therapy significantly improved the patient's strength and quality of life.
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Affiliation(s)
- Midhat Rizvi
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada
- Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada
| | - Tina K Truong
- Center for Human Genetics and Genomics, New York University Grossman School of Medicine, New York, NY, USA
| | - Janet Zhou
- Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada
- Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, Alberta, Canada
| | - Manav Batta
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada
- Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada
| | - Ellen S Moran
- Clinical Genetics, New York University Langone Orthopedic Hospital, New York, NY, USA
| | - John Pappas
- Division of Clinical Genetics, Department of Pediatrics, New York University Grossman School of Medicine, New York, NY, USA
| | - Mary Lynn Chu
- Department of Neurology, New York University School of Medicine, New York, NY, USA
| | - Oana Caluseriu
- Department of Medical Genetics, University of Alberta, Edmonton, Alberta, Canada
- Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada
| | - Gilad D Evrony
- Center for Human Genetics and Genomics, New York University Grossman School of Medicine, New York, NY, USA
- Department of Pediatrics, Department of Neuroscience and Physiology, New York University Grossman School of Medicine, New York, NY, USA
| | - Elaine M Leslie
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada
- Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada
- Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, Alberta, Canada
| | - Emmanuelle Cordat
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada
- Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada
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16
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Krenn M, Sener M, Rath J, Zulehner G, Keritam O, Wagner M, Laccone F, Iglseder S, Marte S, Baumgartner M, Eisenkölbl A, Liechtenstein C, Rudnik S, Quasthoff S, Grinzinger S, Spenger J, Wortmann SB, Löscher WN, Zimprich F, Kellersmann A, Rappold M, Bernert G, Freilinger M, Cetin H. The clinical and molecular landscape of congenital myasthenic syndromes in Austria: a nationwide study. J Neurol 2023; 270:909-916. [PMID: 36308527 PMCID: PMC9886627 DOI: 10.1007/s00415-022-11440-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 10/18/2022] [Accepted: 10/19/2022] [Indexed: 02/03/2023]
Abstract
BACKGROUND Congenital myasthenic syndromes (CMS) are a heterogeneous group of disorders caused by genetic defects resulting in impaired neuromuscular transmission. Although effective treatments are available, CMS is probably underdiagnosed, and systematic clinico-genetic investigations are warranted. METHODS We used a nationwide approach to collect Austrian patients with genetically confirmed CMS. We provide a clinical and molecular characterization of this cohort and aimed to ascertain the current frequency of CMS in Austria. RESULTS Twenty-eight cases with genetically confirmed CMS were identified, corresponding to an overall prevalence of 3.1 per million (95% CI 2.0-4.3) in Austria. The most frequent genetic etiology was CHRNE (n = 13), accounting for 46.4% of the cohort. Within this subgroup, the variant c.1327del, p.(Glu443Lysfs*64) was detected in nine individuals. Moreover, causative variants were found in DOK7 (n = 4), RAPSN (n = 3), COLQ (n = 2), GMPPB (n = 2), CHAT (n = 1), COL13A1 (n = 1), MUSK (n = 1) and AGRN (n = 1). Clinical onset within the first year of life was reported in one half of the patients. Across all subtypes, the most common symptoms were ptosis (85.7%), lower limb (67.9%), upper limb (60.7%) and facial weakness (60.7%). The majority of patients (96.4%) received specific treatment, including acetylcholinesterase inhibitors in 20, adrenergic agonists in 11 and 3,4-diaminopyridine in nine patients. CONCLUSIONS Our study presents the first systematic characterization of individuals with CMS in Austria, providing prevalence estimates and genotype-phenotype correlations that may help to improve the diagnostic approach and patient management.
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Affiliation(s)
- Martin Krenn
- Department of Neurology, Medical University of Vienna, Vienna, Austria
| | - Merve Sener
- Department of Neurology, Medical University of Vienna, Vienna, Austria
| | - Jakob Rath
- Department of Neurology, Medical University of Vienna, Vienna, Austria
| | - Gudrun Zulehner
- Department of Neurology, Medical University of Vienna, Vienna, Austria
| | - Omar Keritam
- Department of Neurology, Medical University of Vienna, Vienna, Austria
| | - Matias Wagner
- Institute of Human Genetics, Technical University of Munich, Munich, Germany.,Institute for Neurogenomics, Helmholtz Center Munich, Munich, Germany
| | - Franco Laccone
- Institute of Medical Genetics, Medical University of Vienna, Vienna, Austria
| | - Stephan Iglseder
- Department of Neurology, Krankenhaus Barmherzige Brüder, Linz, Austria
| | | | - Manuela Baumgartner
- Department of Neuropaediatrics, Hospital Barmherzige Schwestern Linz, Linz, Austria
| | - Astrid Eisenkölbl
- Department of Paediatrics and Adolescent Medicine, Johannes Kepler University Linz, Linz, Austria
| | - Christian Liechtenstein
- Department of Paediatrics and Adolescent Medicine, Villach Regional Hospital, Villach, Austria
| | - Sabine Rudnik
- Institute of Human Genetics, Medical University of Innsbruck, Innsbruck, Austria
| | - Stefan Quasthoff
- Department of Neurology, Medical University of Graz, Graz, Austria
| | - Susanne Grinzinger
- Department of Neurology, Salzburger Landeskliniken, Paracelsus Medical University, Salzburg, Austria
| | - Johannes Spenger
- University Children's Hospital, Paracelsus Medical University, Salzburg, Austria
| | - Saskia B Wortmann
- University Children's Hospital, Paracelsus Medical University, Salzburg, Austria.,Amalia Children's Hospital, Radboudumc, Nijmegen, The Netherlands
| | - Wolfgang N Löscher
- Department of Neurology, Medical University of Innsbruck, Innsbruck, Austria
| | - Fritz Zimprich
- Department of Neurology, Medical University of Vienna, Vienna, Austria
| | | | - Mika Rappold
- Department of Pediatrics, Klinik Favoriten, Vienna, Austria
| | | | - Michael Freilinger
- Department of Pediatrics and Adolescent Medicine, Medical University of Vienna, Vienna, Austria
| | - Hakan Cetin
- Department of Neurology, Medical University of Vienna, Vienna, Austria.
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17
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Pugliese A, Holland SH, Rodolico C, Lochmüller H, Spendiff S. Presynaptic Congenital Myasthenic Syndromes: Understanding Clinical Phenotypes through In vivo Models. J Neuromuscul Dis 2023; 10:731-759. [PMID: 37212067 PMCID: PMC10578258 DOI: 10.3233/jnd-221646] [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] [Accepted: 04/30/2023] [Indexed: 05/23/2023]
Abstract
Presynaptic congenital myasthenic syndromes (CMS) are a group of genetic disorders affecting the presynaptic side of the neuromuscular junctions (NMJ). They can result from a dysfunction in acetylcholine (ACh) synthesis or recycling, in its packaging into synaptic vesicles, or its subsequent release into the synaptic cleft. Other proteins involved in presynaptic endplate development and maintenance can also be impaired.Presynaptic CMS usually presents during the prenatal or neonatal period, with a severe phenotype including congenital arthrogryposis, developmental delay, and apnoeic crisis. However, milder phenotypes with proximal muscle weakness and good response to treatment have been described. Finally, many presynaptic genes are expressed in the brain, justifying the presence of additional central nervous system symptoms.Several animal models have been developed to study CMS, providing the opportunity to identify disease mechanisms and test treatment options. In this review, we describe presynaptic CMS phenotypes with a focus on in vivo models, to better understand CMS pathophysiology and define new causative genes.
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Affiliation(s)
- Alessia Pugliese
- Children’s Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada
- Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Stephen H. Holland
- Children’s Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada
- Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada
| | - Carmelo Rodolico
- Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Hanns Lochmüller
- Children’s Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada
- Department of Medicine, Division of Neurology, The Ottawa Hospital, Ottawa, ON, Canada
- Brain and Mind Research Institute, University of Ottawa, Ottawa, ON, Canada
- Department of Neuropediatrics and Muscle Disorders, Medical Center – University of Freiburg, Faculty of Medicine, Freiburg, Germany
- Centro Nacional de Análisis Genómico (CNAG-CRG), Center for Genomic Regulation, Barcelona Institute of Science and Technology (BIST), Barcelona, Catalonia, Spain
| | - Sally Spendiff
- Children’s Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada
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18
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Abstract
Myasthenia gravis is an autoimmune disorder caused by antibodies against elements in the postsynaptic membrane at the neuromuscular junction, which leads to muscle weakness. Congenital myasthenic syndromes are rare and caused by mutations affecting pre- or postsynaptic function at the neuromuscular synapse and resulting in muscle weakness. MG has a prevalence of 150-250 and an annual incidence of 8-10 individuals per million. The majority has disease onset after age 50 years. Juvenile MG with onset in early childhood is more common in East Asia. MG is subgrouped according to type of pathogenic autoantibodies, age of onset, thymus pathology, and generalization of muscle weakness. More than 80% have antibodies against the acetylcholine receptor. The remaining have antibodies against MuSK, LRP4, or postsynaptic membrane antigens not yet identified. A thymoma is present in 10% of MG patients, and more than one-third of thymoma patients develop MG as a paraneoplastic condition. Immunosuppressive drug therapy, thymectomy, and symptomatic drug therapy with acetylcholine esterase inhibitors represent cornerstones in the treatment. The prognosis is good, with the majority of patients having mild or moderate symptoms only. Most congenital myasthenic syndromes are due to dysfunction in the postsynaptic membrane. Symptom debut is in early life. Symptomatic drug treatment has sometimes a positive effect.
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Affiliation(s)
- Nils Erik Gilhus
- Department of Neurology, Haukeland University Hospital and Department of Clinical Medicine, University of Bergen, Bergen, Norway.
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19
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Shao S, Shi G, Bi FF, Huang K. Pharmacological Treatments for Congenital Myasthenic Syndromes Caused by COLQ Mutations. Curr Neuropharmacol 2023; 21:1594-1605. [PMID: 36703579 PMCID: PMC10472815 DOI: 10.2174/1570159x21666230126145652] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2022] [Revised: 09/30/2022] [Accepted: 11/18/2022] [Indexed: 01/28/2023] Open
Abstract
BACKGROUND Congenital myasthenic syndromes (CMS) refer to a series of inherited disorders caused by defects in various proteins. Mutation in the collagen-like tail subunit of asymmetric acetylcholinesterase (COLQ) is the second-most common cause of CMS. However, data on pharmacological treatments are limited. OBJECTIVE In this study, we reviewed related reports to determine the most appropriate pharmacological strategy for CMS caused by COLQ mutations. A literature review and meta-analysis were also performed. PubMed, MEDLINE, Web of Science, and Cochrane Library databases were searched to identify studies published in English before July 22, 2022. RESULTS A total of 42 studies including 164 patients with CMS due to 72 different COLQ mutations were selected for evaluation. Most studies were case reports, and none were randomized clinical trials. Our meta-analysis revealed evidence that β-adrenergic agonists, including salbutamol and ephedrine, can be used as first-line pharmacological treatments for CMS patients with COLQ mutations, as 98.7% of patients (74/75) treated with β-adrenergic agonists showed positive effects. In addition, AChEIs should be avoided in CMS patients with COLQ mutations, as 90.5% (105/116) of patients treated with AChEIs showed either no or negative effects. CONCLUSION (1) β-adrenergic agonist therapy is the first pharmacological strategy for treating CMS with COLQ mutations. (2) AChEIs should be avoided in patients with CMS with COLQ mutations.
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Affiliation(s)
- Shuai Shao
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan Province, China
- Xiangya School of Medicine, Central South University, Changsha, Hunan province, China
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan Province, China
| | - Guanzhong Shi
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan Province, China
- Xiangya School of Medicine, Central South University, Changsha, Hunan province, China
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan Province, China
| | - Fang-Fang Bi
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan Province, China
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan Province, China
| | - Kun Huang
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan Province, China
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan Province, China
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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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21
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Tayade K, Salunkhe M, Agarwal A, Radhakrishnan DM, Srivastava AK. DOK7 congenital myasthenic syndrome responsive to oral salbutamol. QJM 2022; 115:323-324. [PMID: 35092298 DOI: 10.1093/qjmed/hcac017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Indexed: 11/12/2022] Open
Affiliation(s)
- K Tayade
- From the Department of Neurology, Cardioneurosciences Centre, All India Institute of Medical Sciences, New Delhi, India
| | - M Salunkhe
- From the Department of Neurology, Cardioneurosciences Centre, All India Institute of Medical Sciences, New Delhi, India
| | - A Agarwal
- From the Department of Neurology, Cardioneurosciences Centre, All India Institute of Medical Sciences, New Delhi, India
| | - D M Radhakrishnan
- From the Department of Neurology, Cardioneurosciences Centre, All India Institute of Medical Sciences, New Delhi, India
| | - A K Srivastava
- From the Department of Neurology, Cardioneurosciences Centre, All India Institute of Medical Sciences, New Delhi, India
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