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Kastreva K, Chamova T, Blagoeva S, Bichev S, Mihaylova V, Meyer S, Thompson R, Cherninkova S, Guergueltcheva V, Lochmuller H, Tournev I. Characterization of Clinical Phenotypes in Congenital Myasthenic Syndrome Associated with the c.1327delG Frameshift Mutation in CHRNE Encoding the Acetylcholine Receptor Epsilon Subunit. J Neuromuscul Dis 2024:JND230235. [PMID: 38995797 DOI: 10.3233/jnd-230235] [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: 07/14/2024]
Abstract
Background Congenital myasthenic syndromes (CMS) are a group of rare but often treatable inherited disorders of neuromuscular transmission characterized by fatigable skeletal muscle weakness. In this paper we present the largest phenotypic analysis to date of a cohort of patients carrying the pathogenic variant c.1327delG in the CHRNE gene, leading to CHRNE-CMS. Objective This study aims to identify the phenotypic variability in CMS associated with c.1327delG mutation in the CHRNE gene. Methods Disease specific symptoms were assessed using specific standardized tests for autoimmune myasthenia (Quantitative Myasthenia Gravis score) as well as patient-reported scales for symptom severity. Evaluated clinical manifestations included ocular symptoms (ophthalmoparesis and ptosis), bulbar weakness, axial muscle weakness, proximal and distal muscle weakness, and respiratory function. Patients were allocated into three groups according to clinical impression of disease severity: mild, moderate, and severe. Results We studied 91 Bulgarian Roma patients, carrying the same causative homozygous CHRNE c.1327delG mutation. Bulbar weakness was present in patients throughout all levels of severity of CHRNE-CMS in this study. However, difficulties in eating and swallowing are more prominent characteristics in the moderate and severe clinical phenotypes. Diplopia and ptosis resulting from fatigue of the extraocular muscles were permanent features regardless of disease severity or age. Levels of axial, proximal and distal muscle weakness were variable between disease groups. The statistical analysis showed significant differences between the patients in the three groups, emphasizing a possible variation in symptom manifestation in the evaluated patient population despite the disease originating from the same genetic mutation. Impairment of respiratory function was more prominent in severely affected patients, which might result from loss of compensatory muscle function in those individuals. Conclusion Results from our study indicate significant phenotypic heterogeneity leading to mild, moderate, or severe clinical manifestation in CHRNE-CMS, despite the genotypic homogeneity.
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Affiliation(s)
- Kristina Kastreva
- Department of Neurology, Expert Centre for Hereditary Neurologic and Metabolic Disorders, University Hospital "Alexandrovska", Sofia, Bulgaria
- Medical University - Sofia, Sofia, Bulgaria
| | - Teodora Chamova
- Department of Neurology, Expert Centre for Hereditary Neurologic and Metabolic Disorders, University Hospital "Alexandrovska", Sofia, Bulgaria
- Medical University - Sofia, Sofia, Bulgaria
| | - Stanislava Blagoeva
- Department of Neurology, Expert Centre for Hereditary Neurologic and Metabolic Disorders, University Hospital "Alexandrovska", Sofia, Bulgaria
| | - Stoyan Bichev
- National Genetics Laboratory, University Hospital of Obstetrics and Gynecology - "Maichin Dom"
| | | | - Stefanie Meyer
- Department of Neurology, University Medical Center Goettingen, Goettingen, Germany
- Children's Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada
| | - Rachel Thompson
- Children's Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada
| | - Sylvia Cherninkova
- Department of Neurology, Expert Centre for Hereditary Neurologic and Metabolic Disorders, University Hospital "Alexandrovska", Sofia, Bulgaria
| | - Velina Guergueltcheva
- Department of Neurology, University Hospital "SofiaMed", Sofia, Bulgaria
- Sofia University "St. Kliment Ohridski", Sofia, Bulgaria
| | - Hanns Lochmuller
- 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, Faculty of Medicine, Medical Center-University of Freiburg, Freiburg, Germany
- Centro Nacional de Análisis Genómico (CNAG), Barcelona, Catalonia, Spain
| | - Ivailo Tournev
- Department of Neurology, Expert Centre for Hereditary Neurologic and Metabolic Disorders, University Hospital "Alexandrovska", Sofia, Bulgaria
- Medical University - Sofia, Sofia, Bulgaria
- Department of Cognitive Science and Psychology, New Bulgarian University, Sofia, Bulgaria
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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] [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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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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Wiendl H, Abicht A, Chan A, Della Marina A, Hagenacker T, Hekmat K, Hoffmann S, Hoffmann HS, Jander S, Keller C, Marx A, Melms A, Melzer N, Müller-Felber W, Pawlitzki M, Rückert JC, Schneider-Gold C, Schoser B, Schreiner B, Schroeter M, Schubert B, Sieb JP, Zimprich F, Meisel A. Guideline for the management of myasthenic syndromes. Ther Adv Neurol Disord 2023; 16:17562864231213240. [PMID: 38152089 PMCID: PMC10752078 DOI: 10.1177/17562864231213240] [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: 05/26/2023] [Accepted: 10/23/2023] [Indexed: 12/29/2023] Open
Abstract
Myasthenia gravis (MG), Lambert-Eaton myasthenic syndrome (LEMS), and congenital myasthenic syndromes (CMS) represent an etiologically heterogeneous group of (very) rare chronic diseases. MG and LEMS have an autoimmune-mediated etiology, while CMS are genetic disorders. A (strain dependent) muscle weakness due to neuromuscular transmission disorder is a common feature. Generalized MG requires increasingly differentiated therapeutic strategies that consider the enormous therapeutic developments of recent years. To include the newest therapy recommendations, a comprehensive update of the available German-language guideline 'Diagnostics and therapy of myasthenic syndromes' has been published by the German Neurological society with the aid of an interdisciplinary expert panel. This paper is an adapted translation of the updated and partly newly developed treatment guideline. It defines the rapid achievement of complete disease control in myasthenic patients as a central treatment goal. The use of standard therapies, as well as modern immunotherapeutics, is subject to a staged regimen that takes into account autoantibody status and disease activity. With the advent of modern, fast-acting immunomodulators, disease activity assessment has become pivotal and requires evaluation of the clinical course, including severity and required therapies. Applying MG-specific scores and classifications such as Myasthenia Gravis Activities of Daily Living, Quantitative Myasthenia Gravis, and Myasthenia Gravis Foundation of America allows differentiation between mild/moderate and (highly) active (including refractory) disease. Therapy decisions must consider age, thymic pathology, antibody status, and disease activity. Glucocorticosteroids and the classical immunosuppressants (primarily azathioprine) are the basic immunotherapeutics to treat mild/moderate to (highly) active generalized MG/young MG and ocular MG. Thymectomy is indicated as a treatment for thymoma-associated MG and generalized MG with acetylcholine receptor antibody (AChR-Ab)-positive status. In (highly) active generalized MG, complement inhibitors (currently eculizumab and ravulizumab) or neonatal Fc receptor modulators (currently efgartigimod) are recommended for AChR-Ab-positive status and rituximab for muscle-specific receptor tyrosine kinase (MuSK)-Ab-positive status. Specific treatment for myasthenic crises requires plasmapheresis, immunoadsorption, or IVIG. Specific aspects of ocular, juvenile, and congenital myasthenia are highlighted. The guideline will be further developed based on new study results for other immunomodulators and biomarkers that aid the accurate measurement of disease activity.
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Affiliation(s)
- Heinz Wiendl
- Department of Neurology with Institute of Translational Neurology, University Hospital Münster, Albert-Schweitzer-Campus 1, Building A1, Münster 48149, Germany
| | - Angela Abicht
- Friedrich-Baur-Institut an der Neurologischen Klinik und Poliklinik, LMU Munich, Munich, Germany
| | - Andrew Chan
- Universitätsklinik für Neurologie, Inselspital Bern, Bern, Switzerland
| | - Adela Della Marina
- Klinik für Kinderheilkunde I, Universitätsklinikum Essen, Essen, Germany
| | - Tim Hagenacker
- Klinik für Neurologie, Universitätsklinikum Essen, Essen, Germany
| | | | - Sarah Hoffmann
- Charité – Universitätsmedizin Berlin, Klinik für Neurologie mit Experimenteller Neurologie, Berlin, Germany
| | | | - Sebastian Jander
- Klinik für Neurologie, Marien Hospital Düsseldorf, Düsseldorf, Germany
| | - Christian Keller
- Department of Neurology with Institute of Translational Neurology, University Hospital Münster, Münster, Germany
| | - Alexander Marx
- Pathologisches Institut, Universitätsklinikum Mannheim, Mannheim, Germany
| | - Arthur Melms
- Facharztpraxis für Neurologie und Psychiatrie, Stuttgart, Germany
| | - Nico Melzer
- Klinik für Neurologie, Universitätsklinikum Düsseldorf, Düsseldorf, Germany
| | - Wolfgang Müller-Felber
- Kinderklinik und Kinderpoliklinik im Dr. von Haunerschen Kinderspital, LMU Munich, Munich, Germany
| | - Marc Pawlitzki
- Klinik für Neurologie, Universitätsklinikum Düsseldorf, Düsseldorf, Germany
| | | | | | - Benedikt Schoser
- Friedrich-Baur-Institut an der Neurologischen Klinik und Poliklinik, LMU Munich, Munich, Germany
| | - Bettina Schreiner
- Klinik für Neurologie, Universitätsspital Zürich, Zürich, Switzerland
| | - Michael Schroeter
- Klinik und Poliklinik für Neurologie, Uniklinik Cologne, Cologne, Germany
| | | | | | - Fritz Zimprich
- Universitätsklinik für Neurologie, AKH-Wien, Wien, Austria
| | - Andreas Meisel
- Charité – Universitätsmedizin Berlin, Klinik für Neurologie mit Experimenteller Neurologie, Berlin, Germany
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Spendiff S, Dong Y, Maggi L, Rodríguez Cruz PM, Beeson D, Lochmüller H. 260th ENMC International Workshop: Congenital myasthenic syndromes 11-13 March 2022, Hoofddorp, The Netherlands. Neuromuscul Disord 2023; 33:111-118. [PMID: 36609117 DOI: 10.1016/j.nmd.2022.12.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 12/02/2022] [Accepted: 12/13/2022] [Indexed: 12/23/2022]
Affiliation(s)
- Sally Spendiff
- Children's Hospital of Eastern Ontario Research Institute, Ottawa, Canada
| | - Yin Dong
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
| | - Lorenzo Maggi
- Neuroimmunology and Neuromuscular Diseases Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Pedro M Rodríguez Cruz
- Centro Nacional de Análisis Genómico (CNAG-CRG), Centre for Genomic Regulation, Barcelona, Spain; Department of Human Genetics, Université Cheikh Anta Diop, Dakar, Senegal; Department of Neuromuscular Diseases, UCL Institute of Neurology, London, UK
| | - David Beeson
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
| | - Hanns Lochmüller
- Children's Hospital of Eastern Ontario Research Institute, Ottawa, Canada; Department of Medicine, Division of Neurology, The Ottawa Hospital, Ottawa, Canada; Brain and Mind Research Institute, University of Ottawa, Ottawa, 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.
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Skweres-Kuchta M, Czerska I, Szaruga E. Literature Review on Health Emigration in Rare Diseases-A Machine Learning Perspective. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2023; 20:2483. [PMID: 36767849 PMCID: PMC9915846 DOI: 10.3390/ijerph20032483] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Revised: 01/15/2023] [Accepted: 01/28/2023] [Indexed: 06/18/2023]
Abstract
The article deals with one of the effects of health inequalities and gaps in access to treatments for rare diseases, namely health-driven emigration. The purpose of the paper is to systematize knowledge about the phenomenon of health emigration observed among families affected by rare diseases, for which reimbursed treatment is available, but only in selected countries. The topic proved to be niche; the issue of "health emigration in rare diseases" is an area for exploration. Therefore, the further analysis used text mining and machine learning methods based on a database selected based on keywords related to this issue. The results made it possible to systematize the guesses made by researchers in management and economic fields, to identify the most common keywords and thematic clusters around the perspective of the patient, drug manufacturer and treatment reimbursement decision-maker, and the perspective integrating all the others. Since the topic of health emigration was not directly addressed in the selected sources, the authors attempted to define the related concepts and discussed the importance of this phenomenon in managing the support system in rare diseases. Thus, they indicated directions for further research in this area.
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Affiliation(s)
- Małgorzata Skweres-Kuchta
- Department of Organization and Management, Institute of Management, University of Szczecin, Cukrowa 8 Street, 71-004 Szczecin, Poland
| | - Iwona Czerska
- Department of Marketing Research, Faculty of Management, Wroclaw University of Economics and Business, 118/120 Komandorska Str, 53-345 Wroclaw, Poland
| | - Elżbieta Szaruga
- Department of Transport Management, Institute of Management, University of Szczecin, Cukrowa 8 Street, 71-004 Szczecin, Poland
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7
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Fatema K, Rahman M. Fast channel congenital myesthenic syndrome: Reporting two cases with mutation of CHRNE gene and short review. J Pediatr Neurosci 2022. [DOI: 10.4103/jpn.jpn_124_21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
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8
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Prior DE, Ghosh PS. Congenital Myasthenic Syndrome From a Single Center: Phenotypic and Genotypic features. J Child Neurol 2021; 36:610-617. [PMID: 33471587 DOI: 10.1177/0883073820987755] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND Congenital myasthenic syndrome is a group of rare genetic disorders affecting transmission across the neuromuscular junction. Patients present with variable ocular, bulbar, respiratory, and extremity weakness that may respond to symptomatic therapies. METHODS We identified 18 patients with congenital myasthenic syndrome from a pediatric neuromuscular center over a decade. Through a retrospective chart review, we characterize demographic profile, clinical features, genetic variants, treatment, and follow-up of these patients. RESULTS Patients had the following genetic subtypes: CHRNE (6), CHAT (2), MUSK (2), DOK7 (2), COLQ (1), RAPSN (1), PREPL (1), GFPT1 (1), CHRBB1 (1), and CHRNA1 (1). The phenotype varied based on the genetic variants, though most patients have generalized fatigable weakness affecting ocular, bulbar, and extremity muscles. There was a significant delay in the diagnosis of this condition from the onset of symptoms. Although most patients improved with pyridostigmine, some subtypes showed worsening with pyridostigmine and others benefited from albuterol, ephedrine, or 3,4-diaminopyridine treatment. CONCLUSION Increasing recognition of this rare syndrome will lead to early diagnosis and prompt treatment. Prompt utilization of genetic testing will identify novel variants and the expanding phenotype of this condition.
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Affiliation(s)
- Devin E Prior
- Department of Neurology, 2094Mount Auburn Hospital, Cambridge, MA, USA.,Department of Neurology, 1862Boston Children's Hospital, Boston MA, USA
| | - Partha S Ghosh
- Department of Neurology, 1862Boston Children's Hospital, Boston MA, USA
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9
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Warman-Chardon J, Jasmin BJ, Kothary R, Parks RJ. Report on the 5th Ottawa International Conference on Neuromuscular Disease & Biology -October 17-19, 2019, Ottawa, Canada. J Neuromuscul Dis 2021; 8:323-334. [PMID: 33492242 DOI: 10.3233/jnd-219001] [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]
Affiliation(s)
- Jodi Warman-Chardon
- Department of Medicine, The Ottawa Hospital and University of Ottawa, Canada.,Department of Genetics, Children's Hospital of Eastern Ontario, Canada.,Neuroscience Program, Ottawa Hospital Research Institute, Canada.,Centre for Neuromuscular Disease, University of Ottawa, Canada.,Department of Cellular and Molecular Medicine, University of Ottawa, Canada
| | - Bernard J Jasmin
- Centre for Neuromuscular Disease, University of Ottawa, Canada.,Department of Cellular and Molecular Medicine, University of Ottawa, Canada
| | - Rashmi Kothary
- Department of Medicine, The Ottawa Hospital and University of Ottawa, Canada.,Centre for Neuromuscular Disease, University of Ottawa, Canada.,Department of Cellular and Molecular Medicine, University of Ottawa, Canada.,Regenerative Medicine Program, Ottawa Hospital Research Institute, Canada.,Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Canada
| | - Robin J Parks
- Department of Medicine, The Ottawa Hospital and University of Ottawa, Canada.,Centre for Neuromuscular Disease, University of Ottawa, Canada.,Regenerative Medicine Program, Ottawa Hospital Research Institute, Canada.,Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Canada
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10
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Della Marina A, Wibbeler E, Abicht A, Kölbel H, Lochmüller H, Roos A, Schara U. Long Term Follow-Up on Pediatric Cases With Congenital Myasthenic Syndromes-A Retrospective Single Centre Cohort Study. Front Hum Neurosci 2020; 14:560860. [PMID: 33364925 PMCID: PMC7750519 DOI: 10.3389/fnhum.2020.560860] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2020] [Accepted: 11/16/2020] [Indexed: 02/01/2023] Open
Abstract
Introduction: Congenital myasthenic syndromes (CMS) refer to a heterogenic group of neuromuscular transmission disorders. CMS-subtypes are diverse regarding exercise intolerance and muscular weakness, varying from mild symptoms to life-limiting forms with neonatal onset. Long-term follow-up studies on disease progression and treatment-response in pediatric patients are rare. Patients and Methods: We analyzed retrospective clinical and medication data in a cohort of 32 CMS-patients including the application of a standardized, not yet validated test (CMS-ST) to examine muscular strength and endurance in 21 patients at the last follow-up. Findings obtained in our cohort were compared with long-term follow-up studies of (adult) CMS-cohorts from the literature by considering the underlying molecular mechanisms. Outcomes of CMS-ST were compared to results of normal clinical assessment. Results: Thirty-two pediatric patients with defects in eight different CMS-genes were followed by a median time of 12.8 years. Fifty-nine percentage of patients manifested with first symptoms as neonates, 35% as infants. While 53% of patients presented a reduced walking distance, 34% were wheelchair-bound. Even under adequate therapy with pyridostigmine (PS) and 3,4-diaminopyridine, CHAT-mutations led to the progression of muscular weakness partly in combination with persistent respiratory and bulbar symptoms. RAPSN, CHRND, and CHRNB1 patients with neonatal manifestation, early respiratory problems, and bulbar symptoms showed a good and maintained treatment response. CHAT and CHRNE patients required higher PS dosages, whereas RAPSN patients needed a lower mean dosage at the last follow-up. The benefits of short-term medication and long-term progression of symptoms were highly dependent on the specific genetic defect. CMS-ST was carried out in 17/21 patients, determined affected muscle groups including bulbar and ocular symptoms, some of which were not reported by the patients. Conclusions: Our findings and comparison with the literature- suggest a better treatment-response and less severe progression of symptoms present in patients suffering from mutations in CMS-genes directly associated with receptor deficiency, while patients with defects leading to synaptopathy and presynaptic defects tend to have worse outcomes. Assessment of affected muscular groups and clinical symptoms by CMS-ST may be a useful tool for optimal therapeutic management of the patients, especially for future clinical studies.
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Affiliation(s)
- Adela Della Marina
- Department of Neuropediatrics, Developmental Neurology and Social Pediatrics, University Children's Hospital Essen, University Duisburg-Essen, Essen, Germany
| | - Eva Wibbeler
- Children's Hospital, University Medical Center Hamburg Eppendorf, Hamburg, Germany
| | - Angela Abicht
- Medical Genetic Center Munich, Munich, Germany.,Friedrich-Baur Institute, Ludwig Maximilian University, Munich, Germany
| | - Heike Kölbel
- Department of Neuropediatrics, Developmental Neurology and Social Pediatrics, University Children's Hospital Essen, University Duisburg-Essen, Essen, Germany
| | - Hanns Lochmüller
- Children's Hospital of Eastern Ontario Research Institute, Division of Neurology, Department of Medicine, The Ottawa Hospital, Brain and Mind Research Institute, University of Ottawa, Ottawa, ON, Canada.,Department of Neuropediatrics and Muscle Disorders, Faculty of Medicine, Medical Center-University of Freiburg, Freiburg, Germany.,Centro Nacional de Análisis Genómico (CNAG-CRG), Center for Genomic Regulation, Barcelona Institute of Science and Technology (BIST), Barcelona, Spain
| | - Andreas Roos
- Department of Neuropediatrics, Developmental Neurology and Social Pediatrics, University Children's Hospital Essen, University Duisburg-Essen, Essen, Germany
| | - Ulrike Schara
- Department of Neuropediatrics, Developmental Neurology and Social Pediatrics, University Children's Hospital Essen, University Duisburg-Essen, Essen, Germany
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11
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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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12
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Shen XM, Di L, Shen S, Zhao Y, Neumeyer AM, Selcen D, Sine SM, Engel AG. A novel fast-channel myasthenia caused by mutation in β subunit of AChR reveals subunit-specific contribution of the intracellular M1-M2 linker to channel gating. Exp Neurol 2020; 331:113375. [PMID: 32504635 DOI: 10.1016/j.expneurol.2020.113375] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Revised: 05/27/2020] [Accepted: 06/01/2020] [Indexed: 10/24/2022]
Abstract
Genetic variants causing the fast-channel congenital myasthenic syndrome (CMS) have been identified in the α, δ, and ε but not the β subunit of acetylcholine receptor (AChR). A 16-year-old girl with severe myasthenia had low-amplitude and fast-decaying miniature endplate potentials. Mutation analysis revealed two heteroallelic variants in CHRNB1 encoding the AChR β subunit: a novel c.812C>T (p.P248L) variant in M1-M2 linker (p.P271L in HGVS nomenclature), and a ~430 bp deletion causing loss of exon 8 leading to frame-shift and a premature stop codon (p.G251Dfs*21). P248 is conserved in all β subunits of different species, but not in other AChR subunits. Measurements of radio-labeled α-bungarotoxin binding show that βP248L reduces AChR expression to 60% of wild-type. Patch clamp recordings of ACh-elicited single channel currents demonstrate that βP248L shortens channel opening bursts from 3.3 ms to 1.2 ms, and kinetic analyses predict that the decay of the synaptic response is accelerated 2.4-fold due to reduced probability of channel reopening. Substituting βP248 with threonine, alanine or glycine reduces the burst duration to 2.3, 1.7, and 1.5 ms, respectively. In non-β subunits, substituting leucine for residues corresponding to βP248 prolongs the burst duration to 4.5 ms in the α subunit, shortens it to 2.2 ms in the δ subunit, and has no effect in the ε subunit. Conversely, substituting proline for residues corresponding to βP248 prolongs the burst duration to 8.7 ms in the α subunit, to 4.6 ms in the δ subunit, but has no effect in the ε subunit. Thus, this fast channel CMS is caused by the dual defects of βP248L in reducing expression of the mutant receptor and accelerating the decay of the synaptic response. The results also reveal subunit-specific contributions of the M1-M2 linker to the durations of channel opening bursts.
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Affiliation(s)
- Xin-Ming Shen
- Department of Neurology and Neuromuscular Research Laboratory, Mayo Clinic, Rochester, MN, USA.
| | - Li Di
- Department of Neurology and Neuromuscular Research Laboratory, Mayo Clinic, Rochester, MN, USA
| | - Shelley Shen
- Department of Neurology and Neuromuscular Research Laboratory, Mayo Clinic, Rochester, MN, USA
| | - Yuying Zhao
- Department of Neurology and Neuromuscular Research Laboratory, Mayo Clinic, Rochester, MN, USA
| | - Ann M Neumeyer
- Department of Child Neurology, Massachusetts General Hospital for Children, Lexington, MA, USA
| | - Duygu Selcen
- Department of Neurology and Neuromuscular Research Laboratory, Mayo Clinic, Rochester, MN, USA
| | - Steven M Sine
- Department of Physiology and Biomedical Engineering and Receptor Biology Laboratory, Mayo Clinic, Rochester, MN, USA; Department of Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, MN, USA; Department of Neurology, Mayo Clinic, Rochester, MN, USA
| | - Andrew G Engel
- Department of Neurology and Neuromuscular Research Laboratory, Mayo Clinic, Rochester, MN, USA.
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13
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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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14
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Thompson R, Papakonstantinou Ntalis A, Beltran S, Töpf A, de Paula Estephan E, Polavarapu K, 't Hoen PAC, Missier P, Lochmüller H. Increasing phenotypic annotation improves the diagnostic rate of exome sequencing in a rare neuromuscular disorder. Hum Mutat 2019; 40:1797-1812. [PMID: 31231902 DOI: 10.1002/humu.23792] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Revised: 04/22/2019] [Accepted: 05/08/2019] [Indexed: 12/12/2022]
Abstract
Phenotype-based filtering and prioritization contribute to the interpretation of genetic variants detected in exome sequencing. However, it is currently unclear how extensive this phenotypic annotation should be. In this study, we compare methods for incorporating phenotype into the interpretation process and assess the extent to which phenotypic annotation aids prioritization of the correct variant. Using a cohort of 29 patients with congenital myasthenic syndromes with causative variants in known or newly discovered disease genes, exome data and the Human Phenotype Ontology (HPO)-coded phenotypic profiles, we show that gene-list filters created from phenotypic annotations perform similarly to curated disease-gene virtual panels. We use Exomiser, a prioritization tool incorporating phenotypic comparisons, to rank candidate variants while varying phenotypic annotation. Analyzing 3,712 combinations, we show that increasing phenotypic annotation improved prioritization of the causative variant, from 62% ranked first on variant alone to 90% with seven HPO annotations. We conclude that any HPO-based phenotypic annotation aids variant discovery and that annotation with over five terms is recommended in our context. Although focused on a constrained cohort, this provides real-world validation of the utility of phenotypic annotation for variant prioritization. Further research is needed to extend this concept to other diseases and more diverse cohorts.
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Affiliation(s)
- Rachel Thompson
- Institute of Genetic Medicine, Newcastle University, International Centre for Life, Newcastle upon Tyne, UK
| | - Anastasios Papakonstantinou Ntalis
- Centro Nacional de Análisis Genómico (CNAG-CRG), Center for Genomic Regulation, Barcelona Institute of Science and Technology (BIST), Barcelona, Spain
| | - Sergi Beltran
- Centro Nacional de Análisis Genómico (CNAG-CRG), Center for Genomic Regulation, Barcelona Institute of Science and Technology (BIST), Barcelona, Spain.,Universitat Pompeu Fabra-UPF, Barcelona, Spain
| | - Ana Töpf
- Institute of Genetic Medicine, Newcastle University, International Centre for Life, Newcastle upon Tyne, UK
| | - Eduardo de Paula Estephan
- Departamento de Neurologia, Faculdade de Medicina da Universidade de São Paulo (FMUSP), São Paulo, Brazil
| | - Kiran Polavarapu
- Department of Neurology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India
| | - Peter A C 't Hoen
- Centre for Molecular and Biomolecular Informatics, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center Nijmegen, Nijmegen, The Netherlands
| | - Paolo Missier
- School of Computing, Newcastle University, Newcastle upon Tyne, UK
| | - Hanns Lochmüller
- Centro Nacional de Análisis Genómico (CNAG-CRG), Center for Genomic Regulation, Barcelona Institute of Science and Technology (BIST), Barcelona, Spain.,Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, Canada.,Department of Medicine, Division of Neurology, The Ottawa Hospital, Ottawa, Canada.,Department of Neuropediatrics and Muscle Disorders, Faculty of Medicine, Medical Center-University of Freiburg, Freiburg, Germany
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15
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Grassi F, Fucile S. Calcium influx through muscle nAChR-channels: One route, multiple roles. Neuroscience 2019; 439:117-124. [PMID: 30999028 DOI: 10.1016/j.neuroscience.2019.04.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Revised: 04/01/2019] [Accepted: 04/04/2019] [Indexed: 01/31/2023]
Abstract
Although Ca2+ influx through muscle nAChR-channels has been described over the past 40 years, its functions remain still poorly understood. In this review we suggest possible roles of Ca2+ entry at all stages of muscle development, summarizing the evidence present in literature. nAChRs are expressed in myoblasts prior to fusion, and can be activated in the absence of an ACh-releasing nerve terminal, with Ca2+ influx likely contributing to regulate cell fusion. Upon establishment of nerve-muscle contact, Ca2+ influx contributes to orchestrate the signaling required for the correct formation of the neuromuscular junction. Finally, in the mature synapse, Ca2+ entry through postsynaptic nAChR-channels - highly Ca2+ permeable, in particular in humans - acts on K+ and Na+ channels to shape endplate excitability. However, when genetic defects cause excessive channel activation, Ca2+ influx becomes toxic and causes endplate myopathy. Throughout the review, we highlight how Ricardo Miledi has contributed to construct this whole body of knowledge, from the initial description of Ca2+ permeability of endplate nAChR channels, to the rationale for the treatment of endplate excitotoxic damage under pathological conditions. This article is part of a Special Issue entitled: SI: Honoring Ricardo Miledi - outstanding neuroscientist of XX-XXI centuries.
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Affiliation(s)
- Francesca Grassi
- Department of Physiology and Pharmacology, Sapienza University, piazzale Aldo Moro 5, 00185, Rome, Italy.
| | - Sergio Fucile
- Department of Physiology and Pharmacology, Sapienza University, piazzale Aldo Moro 5, 00185, Rome, Italy; IRCCS Neuromed, Viale dell'Elettronica, 86077, Pozzilli, Italy
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16
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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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