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Sechi E, Deiana GA, Puci M, Zara P, Ortu E, Porcu C, Carboni N, Chessa P, Ruiu E, Nieddu A, Tacconi P, Russo A, Manca D, Sechi MM, Guida M, Ricciardi R, Ercoli T, Mascia MM, Muroni A, Profice P, Saddi V, Melis M, Cocco E, Spagni G, Iorio R, Damato V, Maestri M, Sotgiu S, Sotgiu G, Solla P. Epidemiology of seropositive myasthenia gravis in Sardinia: A population-based study in the district of Sassari. Muscle Nerve 2024; 69:637-642. [PMID: 38456240 DOI: 10.1002/mus.28077] [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: 10/11/2023] [Revised: 02/21/2024] [Accepted: 02/27/2024] [Indexed: 03/09/2024]
Abstract
INTRODUCTION/AIMS The global incidence and prevalence of myasthenia gravis (MG) range between 6-31/million and 10-37/100,000, respectively. Sardinia is a high-risk region for different immune-mediated disorders, but the epidemiology of MG remains unclear. We determined the epidemiology of MG with acetylcholine receptor (AChR)-immunoglobulin G (IgG) and muscle-specific tyrosine kinase (MuSK)-IgG in the district of Sassari (North-Western Sardinia; population, 325,288). METHODS From the laboratory of the University Hospital of Sassari (reference for AChR/MuSK-IgG testing in Sardinia since 1998) and the main neurology units in Sardinia, we retrospectively identified MG patients with (1) AChR-IgG and/or MuSK-IgG positivity by radioimmunoprecipitation assay; and (2) residency in the district of Sassari. Incidence (January 2010-December 2019) and prevalence (December 31, 2019) were calculated. RESULTS A total of 202 patients were included (incident, 107; prevalent, 180). Antibody specificities were AChR (n = 187 [93%]) and MuSK (n = 15 [7%]). The crude MG incidence (95% confidence interval) was 32.6 (26.8-39.2)/million, while prevalence was 55.3 (47.7-63.9)/100,000. After age-standardization to the world population, incidence decreased to 18.4 (14.3-22.5)/million, while prevalence decreased to 31.6 (26.1-37.0)/100,000. Among incident cases, age strata (years) at MG onset were: <18 (2%), 18-49 (14%), 50-64 (21%), and ≥65 (63%). DISCUSSION Sardinia is a high-risk region for MG, with a prevalence that exceeds the European threshold for rare disease. Identification of the environmental and genetic determinants of this risk may improve our understanding of disease pathophysiology.
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Affiliation(s)
- Elia Sechi
- Department of Medical, Surgical and Experimental Sciences, University of Sassari, Sassari, Italy
| | - Giovanni A Deiana
- Department of Medical, Surgical and Experimental Sciences, University of Sassari, Sassari, Italy
| | - Mariangela Puci
- Department of Medicine, Surgery and Pharmacy, University of Sassari, Sassari, Italy
| | - Pietro Zara
- Department of Medical, Surgical and Experimental Sciences, University of Sassari, Sassari, Italy
- Department of Medical Sciences and Public Health, University of Cagliari, Cagliari, Italy
| | - Enzo Ortu
- Department of Medical, Surgical and Experimental Sciences, University of Sassari, Sassari, Italy
| | | | | | - Paola Chessa
- Department of Medical, Surgical and Experimental Sciences, University of Sassari, Sassari, Italy
- Department of Medical Sciences and Public Health, University of Cagliari, Cagliari, Italy
| | - Elisa Ruiu
- Department of Medical, Surgical and Experimental Sciences, University of Sassari, Sassari, Italy
| | - Arianna Nieddu
- Department of Medical, Surgical and Experimental Sciences, University of Sassari, Sassari, Italy
| | - Paolo Tacconi
- Multiple Sclerosis Center, University of Cagliari, Cagliari, Italy
| | | | | | - M Margherita Sechi
- Department of Medical, Surgical and Experimental Sciences, University of Sassari, Sassari, Italy
| | - Melania Guida
- Department of Experimental and Clinical Medicine, University of Pisa, Pisa, Italy
| | - Roberta Ricciardi
- Department of Experimental and Clinical Medicine, University of Pisa, Pisa, Italy
| | - Tommaso Ercoli
- Department of Medical, Surgical and Experimental Sciences, University of Sassari, Sassari, Italy
| | - Marcello M Mascia
- Department of Medical Sciences and Public Health, University of Cagliari, Cagliari, Italy
| | - Antonella Muroni
- Department of Medical Sciences and Public Health, University of Cagliari, Cagliari, Italy
| | - Paolo Profice
- Neurology Unit, Mater Olbia Hospital, Olbia, Italy
- Neurology Unit, Fondazione Policlinico Gemelli, Rome, Italy
| | - Valeria Saddi
- Neurology Unit, Ospedale San Francesco, Nuoro, Italy
| | | | - Eleonora Cocco
- Multiple Sclerosis Center, University of Cagliari, Cagliari, Italy
| | - Gregorio Spagni
- Department of Neuroscience, Università Cattolica del Sacro Cuore, Rome, Italy
| | - Raffaele Iorio
- Department of Neuroscience, Università Cattolica del Sacro Cuore, Rome, Italy
| | - Valentina Damato
- Department of Neurosciences, Drugs and Child Health, University of Florence, Florence, Italy
| | - Michelangelo Maestri
- Department of Experimental and Clinical Medicine, University of Pisa, Pisa, Italy
| | - Stefano Sotgiu
- Department of Medical, Surgical and Experimental Sciences, University of Sassari, Sassari, Italy
| | - Giovanni Sotgiu
- Department of Medicine, Surgery and Pharmacy, University of Sassari, Sassari, Italy
| | - Paolo Solla
- Department of Medical, Surgical and Experimental Sciences, University of Sassari, Sassari, Italy
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Yasuda M, Uzawa A, Kuwabara S, Suzuki S, Akamine H, Onishi Y, Ozawa Y, Kawaguchi N, Kubota T, Takahashi MP, Suzuki Y, Watanabe G, Kimura T, Sugimoto T, Samukawa M, Minami N, Masuda M, Konno S, Nagane Y, Utsugisawa K. Clinical features and outcomes of patients with muscle-specific kinase antibody-positive myasthenia gravis in Japan. J Neuroimmunol 2023; 385:578241. [PMID: 37952282 DOI: 10.1016/j.jneuroim.2023.578241] [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: 09/25/2023] [Revised: 10/31/2023] [Accepted: 11/05/2023] [Indexed: 11/14/2023]
Abstract
This study included 51 patients with muscle-specific kinase antibody-positive myasthenia gravis (MuSK-MG) from a Japanese multicenter survey to examine clinical features and outcomes. Median onset age was 37 years and female predominance was observed. All patients developed generalized symptoms and almost all (50/51) patients had bulbar symptoms. About half of the patients met the criteria for refractory MG. The refractory group had a lower age of onset, higher severity scores, and higher maximum daily doses of oral prednisolone compared to the nonrefractory group. The outcomes for MuSK-MG patients in Japan are not favorable, indicating the need for more aggressive treatment.
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Affiliation(s)
- Manato Yasuda
- Department of Neurology, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Akiyuki Uzawa
- Department of Neurology, Graduate School of Medicine, Chiba University, Chiba, Japan.
| | - Satoshi Kuwabara
- Department of Neurology, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Shigeaki Suzuki
- Department of Neurology, Keio University School of Medicine, Tokyo, Japan
| | - Hiroyuki Akamine
- Department of Neurology, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Yosuke Onishi
- Department of Neurology, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Yukiko Ozawa
- Department of Neurology, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Naoki Kawaguchi
- Department of Neurology, Neurology Chiba Clinic, Chiba, Japan
| | - Tomoya Kubota
- Department of Clinical Laboratory and Biomedical Sciences, Division of Health Sciences, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Masanori P Takahashi
- Department of Clinical Laboratory and Biomedical Sciences, Division of Health Sciences, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Yasushi Suzuki
- Department of Neurology, National Hospital Organization Sendai Medical Center, Sendai, Japan
| | - Genya Watanabe
- Department of Neurology, National Hospital Organization Sendai Medical Center, Sendai, Japan
| | - Takashi Kimura
- Department of Neurology, Hyogo Medical University, Nishinomiya, Japan
| | - Takamichi Sugimoto
- Department of Clinical Neuroscience and Therapeutics, Hiroshima University, Hiroshima, Japan
| | - Makoto Samukawa
- Department of Neurology, Kindai University Faculty of Medicine, Osaka, Japan
| | - Naoya Minami
- Department of Neurology, National Hospital Organization Hokkaido Medical Center, Sapporo, Japan
| | - Masayuki Masuda
- Department of Neurology, Tokyo Medical University, Tokyo, Japan
| | - Shingo Konno
- Department of Neurology, Toho University Ohashi Medical Center, Tokyo, Japan
| | - Yuriko Nagane
- Department of Neurology, Hanamaki General Hospital, Hanamaki, Japan
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Golfinopoulou R, Giudicelli V, Manso T, Kossida S. Delving into Molecular Pathways: Analyzing the Mechanisms of Action of Monoclonal Antibodies Integrated in IMGT/mAb-DB for Myasthenia Gravis. Vaccines (Basel) 2023; 11:1756. [PMID: 38140161 PMCID: PMC10747390 DOI: 10.3390/vaccines11121756] [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: 09/30/2023] [Revised: 11/20/2023] [Accepted: 11/22/2023] [Indexed: 12/24/2023] Open
Abstract
BACKGROUND Myasthenia Gravis (MG) is a rare autoimmune disease presenting with auto-antibodies that affect the neuromuscular junction. In addition to symptomatic treatment options, novel therapeutics include monoclonal antibodies (mAbs). IMGT®, the international ImMunoGeneTics information system®, extends the characterization of therapeutic antibodies with a systematic description of their mechanisms of action (MOA) and makes them available through its database for mAbs and fusion proteins, IMGT/mAb-DB. METHODS Using available literature data combined with amino acid sequence analyses from mAbs managed in IMGT/2Dstructure-DB, the IMGT® protein database, biocuration allowed us to define in a standardized way descriptions of MOAs of mAbs that target molecules towards MG treatment. RESULTS New therapeutic targets include FcRn and molecules such as CD38, CD40, CD19, MS4A1, and interleukin-6 receptor. A standardized graphical representation of the MOAs of selected mAbs was created and integrated within IMGT/mAb-DB. The main mechanisms involved in these mAbs are either blocking or neutralizing. Therapies directed to B cell depletion and plasma cells have a blocking MOA with an immunosuppressant effect along with Fc-effector function (MS4A1, CD38) or FcγRIIb engager effect (CD19). Monoclonal antibodies targeting the complement also have a blocking MOA with a complement inhibitor effect, and treatments targeting T cells have a blocking MOA with an immunosuppressant effect (CD40) and Fc-effector function (IL6R). On the other hand, FcRn antagonists present a neutralizing MOA with an FcRn inhibitor effect. CONCLUSION The MOA of each new mAb needs to be considered in association with the immunopathogenesis of each of the subtypes of MG in order to integrate the new mAbs as a viable and safe option in the therapy decision process. In IMGT/mAb-DB, mAbs for MG are characterized by their sequence, domains, and chains, and their MOA is described.
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Affiliation(s)
- Rebecca Golfinopoulou
- IMGT, The International ImMunoGeneTics Information System, National Center for Scientific Research (CNRS), Institute of Human Genetics (IGH), University of Montpellier (UM), 34090 Montpellier, France; (R.G.); (V.G.)
- Department of Biotechnology, School of Applied Biology and Biotechnology, Agricultural University of Athens, 11855 Athens, Greece
| | - Véronique Giudicelli
- IMGT, The International ImMunoGeneTics Information System, National Center for Scientific Research (CNRS), Institute of Human Genetics (IGH), University of Montpellier (UM), 34090 Montpellier, France; (R.G.); (V.G.)
| | - Taciana Manso
- IMGT, The International ImMunoGeneTics Information System, National Center for Scientific Research (CNRS), Institute of Human Genetics (IGH), University of Montpellier (UM), 34090 Montpellier, France; (R.G.); (V.G.)
| | - Sofia Kossida
- IMGT, The International ImMunoGeneTics Information System, National Center for Scientific Research (CNRS), Institute of Human Genetics (IGH), University of Montpellier (UM), 34090 Montpellier, France; (R.G.); (V.G.)
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Vakrakou AG, Karachaliou E, Chroni E, Zouvelou V, Tzanetakos D, Salakou S, Papadopoulou M, Tzartos S, Voumvourakis K, Kilidireas C, Giannopoulos S, Tsivgoulis G, Tzartos J. Immunotherapies in MuSK-positive Myasthenia Gravis; an IgG4 antibody-mediated disease. Front Immunol 2023; 14:1212757. [PMID: 37564637 PMCID: PMC10410455 DOI: 10.3389/fimmu.2023.1212757] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Accepted: 07/05/2023] [Indexed: 08/12/2023] Open
Abstract
Muscle-specific kinase (MuSK) Myasthenia Gravis (MG) represents a prototypical antibody-mediated disease characterized by predominantly focal muscle weakness (neck, facial, and bulbar muscles) and fatigability. The pathogenic antibodies mostly belong to the immunoglobulin subclass (Ig)G4, a feature which attributes them their specific properties and pathogenic profile. On the other hand, acetylcholine receptor (AChR) MG, the most prevalent form of MG, is characterized by immunoglobulin (Ig)G1 and IgG3 antibodies to the AChR. IgG4 class autoantibodies are impotent to fix complement and only weakly bind Fc-receptors expressed on immune cells and exert their pathogenicity via interfering with the interaction between their targets and binding partners (e.g. between MuSK and LRP4). Cardinal differences between AChR and MuSK-MG are the thymus involvement (not prominent in MuSK-MG), the distinct HLA alleles, and core immunopathological patterns of pathology in neuromuscular junction, structure, and function. In MuSK-MG, classical treatment options are usually less effective (e.g. IVIG) with the need for prolonged and high doses of steroids difficult to be tapered to control symptoms. Exceptional clinical response to plasmapheresis and rituximab has been particularly observed in these patients. Reduction of antibody titers follows the clinical efficacy of anti-CD20 therapies, a feature implying the role of short-lived plasma cells (SLPB) in autoantibody production. Novel therapeutic monoclonal against B cells at different stages of their maturation (like plasmablasts), or against molecules involved in B cell activation, represent promising therapeutic targets. A revolution in autoantibody-mediated diseases is pharmacological interference with the neonatal Fc receptor, leading to a rapid reduction of circulating IgGs (including autoantibodies), an approach already suitable for AChR-MG and promising for MuSK-MG. New precision medicine approaches involve Chimeric autoantibody receptor T (CAAR-T) cells that are engineered to target antigen-specific B cells in MuSK-MG and represent a milestone in the development of targeted immunotherapies. This review aims to provide a detailed update on the pathomechanisms involved in MuSK-MG (cellular and humoral aberrations), fostering the understanding of the latest indications regarding the efficacy of different treatment strategies.
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Affiliation(s)
- Aigli G. Vakrakou
- First Department of Neurology, Medical School, National and Kapodistrian University of Athens, Athens, Greece
| | - Eleni Karachaliou
- Second Department of Neurology, Attikon University Hospital, National and Kapodistrian University of Athens, Athens, Greece
| | - Elisabeth Chroni
- Department of Neurology, School of Medicine, University of Patras, Patras, Greece
| | - Vasiliki Zouvelou
- First Department of Neurology, Medical School, National and Kapodistrian University of Athens, Athens, Greece
| | - Dimitrios Tzanetakos
- Second Department of Neurology, Attikon University Hospital, National and Kapodistrian University of Athens, Athens, Greece
| | - Stavroula Salakou
- Second Department of Neurology, Attikon University Hospital, National and Kapodistrian University of Athens, Athens, Greece
| | - Marianna Papadopoulou
- Second Department of Neurology, Attikon University Hospital, National and Kapodistrian University of Athens, Athens, Greece
- Department of Physiotherapy, University of West Attica, Athens, Greece
| | - Socrates Tzartos
- Tzartos NeuroDiagnostics, Athens, Greece
- Department of Neurobiology, Hellenic Pasteur Institute, Athens, Greece
- Department of Pharmacy, University of Patras, Patras, Greece
| | - Konstantinos Voumvourakis
- Second Department of Neurology, Attikon University Hospital, National and Kapodistrian University of Athens, Athens, Greece
| | - Constantinos Kilidireas
- First Department of Neurology, Medical School, National and Kapodistrian University of Athens, Athens, Greece
- Department of Neurology, Henry Dunant Hospital Center, Athens, Greece
| | - Sotirios Giannopoulos
- Second Department of Neurology, Attikon University Hospital, National and Kapodistrian University of Athens, Athens, Greece
| | - Georgios Tsivgoulis
- Second Department of Neurology, Attikon University Hospital, National and Kapodistrian University of Athens, Athens, Greece
- Department of Neurology, The University of Tennessee Health Science Center, Memphis, TN, United States
| | - John Tzartos
- Second Department of Neurology, Attikon University Hospital, National and Kapodistrian University of Athens, Athens, Greece
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Salari N, Fatahi B, Bartina Y, Kazeminia M, Fatahian R, Mohammadi P, Shohaimi S, Mohammadi M. Global prevalence of myasthenia gravis and the effectiveness of common drugs in its treatment: a systematic review and meta-analysis. J Transl Med 2021; 19:516. [PMID: 34930325 PMCID: PMC8686543 DOI: 10.1186/s12967-021-03185-7] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Accepted: 12/06/2021] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND Myasthenia gravis is a neuromuscular autoimmune disorder characterized by weakness and disability in the voluntary muscles. There have been several preliminary studies on the epidemiology of myasthenia gravis in different parts of the world and the effectiveness of common drugs in its treatment, but there has been no comprehensive study of the efficacy of common drugs in the treatment of myasthenia gravis. Therefore, this study aimed to determine the epidemiology of myasthenia gravis globally and the effectiveness of common drugs in its treatment using systematic review and meta-analysis. METHODS Research studies were extracted from IranDoc, MagIran, IranMedex, SID, ScienceDirect, Web of Sciences (WoS), ProQuest, Medline (PubMed), Scopus and Google Scholar based on Cochran's seven-step guidelines using existing keywords extracted in MeSH browser. The I2 test was used to calculate the heterogeneity of studies, and Begg and Mazumdar rank correlation tests were used to assess publication bias. Data were analyzed using Comprehensive Meta-Analysis software (Version 2). RESULTS In the search for descriptive studies based on the research question, 7374 articles were found. After deleting articles unrelated to the research question, finally, 63 articles with a sample size of 1,206,961,907 people were included in the meta-analysis. The prevalence of MG worldwide was estimated to be 12.4 people (95% CI 10.6-14.5) per 100,000 population. For analytical studies on the effectiveness of common myasthenia gravis drugs, 4672 articles were found initially, and after removing articles unrelated to the research question, finally, 20 articles with a sample size of 643 people in the drug group and 619 people in the placebo group were included in the study. As a result of the combination of studies, the difference between the mean QMGS score index after taking Mycophenolate and Immunoglobulin or plasma exchange drugs in the group of patients showed a significant decrease of 1.4 ± 0.77 and 0.62 ± 0.28, respectively (P < 0.01). CONCLUSION The results of systematic review of drug evaluation in patients with myasthenia gravis showed that Mycophenolate and Immunoglobulin or plasma exchange drugs have positive effects in the treatment of MG. It also represents the positive effect of immunoglobulin or plasma exchange on reducing SFEMG index and QMGS index and the positive effect of Mycophenolate in reducing MG-ADL index, SFEMG and Anti-AChR antibodies index. In addition, based on a meta-analysis of the random-effect model, the overall prevalence of MG in the world is 12.4 people per 100,000 population, which indicates the urgent need for attention to this disease for prevention and treatment.
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Affiliation(s)
- Nader Salari
- Department of Biostatistics, School of Health, Kermanshah University of Medical Sciences, Kermanshah, Iran
| | - Behnaz Fatahi
- Student Research Committee, Kermanshah University of Medical Sciences, Kermanshah, Iran
| | - Yalda Bartina
- Department of Translation Studies, Faculty of Literature, Istanbul University, Istanbul, Turkey
| | - Mohsen Kazeminia
- Student Research Committee, Kermanshah University of Medical Sciences, Kermanshah, Iran
| | - Reza Fatahian
- Department of Neurosurgery, School of Medicine, Kermanshah University of Medical Sciences, Kermanshah, Iran
| | - Payam Mohammadi
- Department of Neurology, School of Medicine, Kermanshah University of Medical Sciences, Kermanshah, Iran
| | - Shamarina Shohaimi
- Department of Biology, Faculty of Science, University Putra Malaysia, Serdang, Selangor Malaysia
| | - Masoud Mohammadi
- Cellular and Molecular Research Center, Gerash University of Medical Sciences, Gerash, Iran
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Pharmacological Management of Myasthenia Gravis: A Century of Expert Opinions in Cecil Textbook of Medicine. Am J Ther 2021; 28:e631-e637. [PMID: 34757964 DOI: 10.1097/mjt.0000000000001454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND Advances in drug therapy for myasthenia gravis have had a significant impact on the quality of life and work potential of a substantial majority of affected persons and has contributed to a remarkable decrease in the frequency and severity of complications, hospitalizations, and mortality. STUDY QUESTION What are the milestones of the changes in the expert approach to the pharmacological management of myasthenia in the past century? STUDY DESIGN To determine the changes in the experts' approach to the management of myasthenia gravis, as presented in a widely used textbook in the United States. DATA SOURCES The chapters presenting the management of myasthenia gravis in the 26 editions of Cecil Textbook of Medicine published from 1927 to 2020. RESULTS Adequate feeding, absolute rest in bed, and "tonics" were the only interventions recommended for the care of patients with myasthenia gravis in 1927. Ephedrine and glycine were used in the early 1930s. Treatment with the anticholinesterases physostigmine and neostigmine was recommended in 1937, 3 years after Mary Walker discovered it in the United Kingdom. Immunosuppressant pharmacological interventions with prednisone and azathioprine have been considered the standard since 1975, and intravenous immune globulin was added to usual care in 1996. The newer immunosuppressant drugs mycophenolate, cyclosporine, and tacrolimus have expanded the arsenal since 2008, and the monoclonal antibodies rituximab and eculizumab have been mentioned in the textbooks published in 2012-2020. The first randomized clinical trial of drug therapy for myasthenia gravis was published in 1987. CONCLUSIONS The pharmacological management of myasthenia gravis was revolutionized by the epiphany of an astute clinician in the 1930s. Immunosuppressant treatment was a logical step once the autoimmune nature of the condition was established. The major therapeutic advances highlight the values of empiricism and persistent attention to detail in treating relatively rare chronic disorders.
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Yu Z, Zhang M, Jing H, Chen P, Cao R, Pan J, Luo B, Yu Y, Quarles BM, Xiong W, Rivner MH, Mei L. Characterization of LRP4/Agrin Antibodies From a Patient With Myasthenia Gravis. Neurology 2021; 97:e975-e987. [PMID: 34233932 PMCID: PMC8448554 DOI: 10.1212/wnl.0000000000012463] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Accepted: 06/22/2021] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND AND OBJECTIVE To determine whether human anti-LRP4/agrin antibodies are pathogenic in mice and to investigate underpinning pathogenic mechanisms. METHODS Immunoglobulin (Ig) was purified from a patient with myasthenia gravis (MG) with anti-LRP4/agrin antibodies and transferred to mice. Mice were characterized for body weight, muscle strength, twitch and tetanic force, neuromuscular junction (NMJ) functions including compound muscle action potential (CMAP) and endplate potentials, and NMJ structure. Effects of the antibodies on agrin-elicited muscle-specific tyrosine kinase (MuSK) activation and AChR clustering were studied and the epitopes of these antibodies were identified. RESULTS Patient Ig-injected mice had MG symptoms, including weight loss and muscle weakness. Decreased CMAPs, reduced twitch and tetanus force, compromised neuromuscular transmission, and NMJ fragmentation and distortion were detected in patient Ig-injected mice. Patient Ig inhibited agrin-elicited MuSK activation and AChR clustering. The patient Ig recognized the β3 domain of LRP4 and the C-terminus of agrin and reduced agrin-enhanced LRP4-MuSK interaction. DISCUSSION Anti-LRP4/agrin antibodies in the patient with MG is pathogenic. It impairs the NMJ by interrupting agrin-dependent LRP4-MuSK interaction.
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Affiliation(s)
- Zheng Yu
- From the Department of Neurosciences (Z.Y., M.Z., H.J., P.C., R.C., J.P., B.L., W.X., L.M.), School of Medicine, Case Western Reserve University, Cleveland; Beachwood High School (Y.Y.), OH; Department of Neurology (B.M.Q., M.H.R.), Augusta University, GA; and Louis Stokes Cleveland Veterans Affairs Medical Center (W.X., L.M.), OH
| | - Meiying Zhang
- From the Department of Neurosciences (Z.Y., M.Z., H.J., P.C., R.C., J.P., B.L., W.X., L.M.), School of Medicine, Case Western Reserve University, Cleveland; Beachwood High School (Y.Y.), OH; Department of Neurology (B.M.Q., M.H.R.), Augusta University, GA; and Louis Stokes Cleveland Veterans Affairs Medical Center (W.X., L.M.), OH
| | - Hongyang Jing
- From the Department of Neurosciences (Z.Y., M.Z., H.J., P.C., R.C., J.P., B.L., W.X., L.M.), School of Medicine, Case Western Reserve University, Cleveland; Beachwood High School (Y.Y.), OH; Department of Neurology (B.M.Q., M.H.R.), Augusta University, GA; and Louis Stokes Cleveland Veterans Affairs Medical Center (W.X., L.M.), OH
| | - Peng Chen
- From the Department of Neurosciences (Z.Y., M.Z., H.J., P.C., R.C., J.P., B.L., W.X., L.M.), School of Medicine, Case Western Reserve University, Cleveland; Beachwood High School (Y.Y.), OH; Department of Neurology (B.M.Q., M.H.R.), Augusta University, GA; and Louis Stokes Cleveland Veterans Affairs Medical Center (W.X., L.M.), OH
| | - Rangjuan Cao
- From the Department of Neurosciences (Z.Y., M.Z., H.J., P.C., R.C., J.P., B.L., W.X., L.M.), School of Medicine, Case Western Reserve University, Cleveland; Beachwood High School (Y.Y.), OH; Department of Neurology (B.M.Q., M.H.R.), Augusta University, GA; and Louis Stokes Cleveland Veterans Affairs Medical Center (W.X., L.M.), OH
| | - Jinxiu Pan
- From the Department of Neurosciences (Z.Y., M.Z., H.J., P.C., R.C., J.P., B.L., W.X., L.M.), School of Medicine, Case Western Reserve University, Cleveland; Beachwood High School (Y.Y.), OH; Department of Neurology (B.M.Q., M.H.R.), Augusta University, GA; and Louis Stokes Cleveland Veterans Affairs Medical Center (W.X., L.M.), OH
| | - Bin Luo
- From the Department of Neurosciences (Z.Y., M.Z., H.J., P.C., R.C., J.P., B.L., W.X., L.M.), School of Medicine, Case Western Reserve University, Cleveland; Beachwood High School (Y.Y.), OH; Department of Neurology (B.M.Q., M.H.R.), Augusta University, GA; and Louis Stokes Cleveland Veterans Affairs Medical Center (W.X., L.M.), OH
| | - Yue Yu
- From the Department of Neurosciences (Z.Y., M.Z., H.J., P.C., R.C., J.P., B.L., W.X., L.M.), School of Medicine, Case Western Reserve University, Cleveland; Beachwood High School (Y.Y.), OH; Department of Neurology (B.M.Q., M.H.R.), Augusta University, GA; and Louis Stokes Cleveland Veterans Affairs Medical Center (W.X., L.M.), OH
| | - Brandy M Quarles
- From the Department of Neurosciences (Z.Y., M.Z., H.J., P.C., R.C., J.P., B.L., W.X., L.M.), School of Medicine, Case Western Reserve University, Cleveland; Beachwood High School (Y.Y.), OH; Department of Neurology (B.M.Q., M.H.R.), Augusta University, GA; and Louis Stokes Cleveland Veterans Affairs Medical Center (W.X., L.M.), OH
| | - Wencheng Xiong
- From the Department of Neurosciences (Z.Y., M.Z., H.J., P.C., R.C., J.P., B.L., W.X., L.M.), School of Medicine, Case Western Reserve University, Cleveland; Beachwood High School (Y.Y.), OH; Department of Neurology (B.M.Q., M.H.R.), Augusta University, GA; and Louis Stokes Cleveland Veterans Affairs Medical Center (W.X., L.M.), OH
| | - Michael H Rivner
- From the Department of Neurosciences (Z.Y., M.Z., H.J., P.C., R.C., J.P., B.L., W.X., L.M.), School of Medicine, Case Western Reserve University, Cleveland; Beachwood High School (Y.Y.), OH; Department of Neurology (B.M.Q., M.H.R.), Augusta University, GA; and Louis Stokes Cleveland Veterans Affairs Medical Center (W.X., L.M.), OH.
| | - Lin Mei
- From the Department of Neurosciences (Z.Y., M.Z., H.J., P.C., R.C., J.P., B.L., W.X., L.M.), School of Medicine, Case Western Reserve University, Cleveland; Beachwood High School (Y.Y.), OH; Department of Neurology (B.M.Q., M.H.R.), Augusta University, GA; and Louis Stokes Cleveland Veterans Affairs Medical Center (W.X., L.M.), OH.
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8
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Belimezi M, Kalliaropoulos A, Jiménez J, Garcia I, Mentis AFA, Chrousos GP. Age at sampling and sex distribution of AChRAb vs. MuSKAb myasthenia gravis in a large Greek population. Clin Neurol Neurosurg 2021; 208:106847. [PMID: 34343914 DOI: 10.1016/j.clineuro.2021.106847] [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: 04/05/2021] [Revised: 07/22/2021] [Accepted: 07/24/2021] [Indexed: 10/20/2022]
Abstract
OBJECTIVE Myasthenia gravis (MG) is a typical B-cell-mediated neuromuscular junction disease that can be classified into seropositive and seronegative subtypes. Association of patients' age at sampling and sex with the two major seropositive MG subcategories, i.e., MGs linked to antibodies directed against the acetylcholine receptor (AChRAb) and against the muscle-specific kinase (MuSKAb), has not been compared in a large population. METHODS We performed a retrospective analysis of samples from patients with MG in Greece who underwent neurochemical diagnostic evaluation between January 2, 2013, and August 31, 2016. RESULTS Overall, 1620 adult (623 male and 997 female patients; male-to-female ratio = 0.62) and 51 pediatric patients were found to be seropositive for MG. The distributions in both male and female patients were bimodal in the total and AChRAb MG cases but not in the total MuSKAb MG cases. Significant differences in the age at sampling distribution between the male and female adult patients were observed only in the AChRAb MG subtype. Significant differences between the AChRAb and MuSKAb MG categories were noted in the mean age values (60.10 and 51.49 years, respectively, for female and 65.69 and 56.19 years, respectively, for male adult patients). CONCLUSION Our findings confirm an uneven profile of age at sampling and sex between the AChRAb and MuSKAb MG cases in a large population. Future mechanistic studies can elucidate the cause of these differences. Moreover, clinical studies can explore how such differences can affect MG treatment and prognosis.
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Affiliation(s)
- Maria Belimezi
- Diagnostic Services Laboratory, Hellenic Pasteur Institute, Athens, Greece
| | | | - Juan Jiménez
- ADEMA Universitary School, University of the Balearic Islands (UIB), Palma, Balearic Islands, Spain
| | - Irene Garcia
- Department of Mathematical Sciences and Informatics, and Health Research Institute (IdISBa), University of the Balearic Islands (UIB), Palma, Balearic Islands, Spain
| | - Alexios-Fotios A Mentis
- Diagnostic Services Laboratory, Hellenic Pasteur Institute, Athens, Greece; University Research Institute of Maternal and Child Health and Precision Medicine, National and Kapodistrian University of Athens, Levadias, Athens, Greece.
| | - George P Chrousos
- University Research Institute of Maternal and Child Health and Precision Medicine, National and Kapodistrian University of Athens, Levadias, Athens, Greece
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9
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Eker A, Tınazlı M, Mut SE. Coexistence of anti-MuSK antibody-positive myasthenia gravis and rheumatoid arthritis. THE EGYPTIAN JOURNAL OF NEUROLOGY, PSYCHIATRY AND NEUROSURGERY 2020. [DOI: 10.1186/s41983-020-00222-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Abstract
Background
Rheumatoid arthritis (RA) is an autoimmune disease characterized with symmetric synovitis and occasional extra articular involvement; also, some neurologic disorders can be observed during the disease course. Myasthenia gravis (MG) is one of them and it is an autoimmune disease of neuromuscular junction. It is caused by autoantibodies against neuromuscular junction proteins: the nicotinic acetylcholine receptor (AChR) and the muscle specific tyrosine kinase (MuSK). Very few studies have reported the associated autoimmune disorders in MuSK-MG. Here, we present the first patient who has MuSK antibody-positive MG gravis and rheumatoid arthritis.
Case presentation
A 53-year-old woman with RA presented with fatigue and fluctuating proximal muscle weakness. Her electroneurophysiological investigation resembled MG. Her AchR antibody level was normal but MuSK antibodies were high. After the acute treatment with plasmapheresis which lead to complete recovery in myasthenic symptoms, she is following with mycophenolate mofetil.
Conclusions
Concomitant autoimmune disorders are common in the population. MG should be considered in patients with an autoimmune disorder and developing new neuromuscular weakness.
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10
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Lazaridis K, Tzartos SJ. Myasthenia Gravis: Autoantibody Specificities and Their Role in MG Management. Front Neurol 2020; 11:596981. [PMID: 33329350 PMCID: PMC7734299 DOI: 10.3389/fneur.2020.596981] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Accepted: 10/30/2020] [Indexed: 12/11/2022] Open
Abstract
Myasthenia gravis (MG) is the most common autoimmune disorder affecting the neuromuscular junction, characterized by skeletal muscle weakness and fatigability. It is caused by autoantibodies targeting proteins of the neuromuscular junction; ~85% of MG patients have autoantibodies against the muscle acetylcholine receptor (AChR-MG), whereas about 5% of MG patients have autoantibodies against the muscle specific kinase (MuSK-MG). In the remaining about 10% of patients no autoantibodies can be found with the classical diagnostics for AChR and MuSK antibodies (seronegative MG, SN-MG). Since serological tests are relatively easy and non-invasive for disease diagnosis, the improvement of methods for the detection of known autoantibodies or the discovery of novel autoantibody specificities to diminish SN-MG and to facilitate differential diagnosis of similar diseases, is crucial. Radioimmunoprecipitation assays (RIPA) are the staple for MG antibody detection, but over the past years, using cell-based assays (CBAs) or improved highly sensitive RIPAs, it has been possible to detect autoantibodies in previously SN-MG patients. This led to the identification of more patients with antibodies to the classical antigens AChR and MuSK and to the third MG autoantigen, the low-density lipoprotein receptor-related protein 4 (LRP4), while antibodies against other extracellular or intracellular targets, such as agrin, Kv1.4 potassium channels, collagen Q, titin, the ryanodine receptor and cortactin have been found in some MG patients. Since the autoantigen targeted determines in part the clinical manifestations, prognosis and response to treatment, serological tests are not only indispensable for initial diagnosis, but also for monitoring treatment efficacy. Importantly, knowing the autoantibody profile of MG patients could allow for more efficient personalized therapeutic approaches. Significant progress has been made over the past years toward the development of antigen-specific therapies, targeting only the specific immune cells or autoantibodies involved in the autoimmune response. In this review, we will present the progress made toward the development of novel sensitive autoantibody detection assays, the identification of new MG autoantigens, and the implications for improved antigen-specific therapeutics. These advancements increase our understanding of MG pathology and improve patient quality of life by providing faster, more accurate diagnosis and better disease management.
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Affiliation(s)
| | - Socrates J Tzartos
- Tzartos NeuroDiagnostics, Athens, Greece.,Department of Neurobiology, Hellenic Pasteur Institute, Athens, Greece
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11
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Westerberg E, Punga AR. Epidemiology of Myasthenia Gravis in Sweden 2006-2016. Brain Behav 2020; 10:e01819. [PMID: 32869520 PMCID: PMC7667338 DOI: 10.1002/brb3.1819] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 08/11/2020] [Accepted: 08/12/2020] [Indexed: 12/04/2022] Open
Abstract
INTRODUCTION Reported incidence and prevalence rates of Myasthenia Gravis (MG) vary widely and are assumed to have increased over the last few decades. We conducted a nationwide register-based study on the current incidence and prevalence of MG and MG subgroups in Sweden. METHODS Data were acquired from four Swedish Health Registers in order to identify patients with MG. Incidence and prevalence rates were calculated for the years 2006-2016, using population numbers provided by Statistics Sweden. RESULTS In 2016, the incidence of MG in Sweden was 2.9 per 100,000 inhabitants (95% CI: 2.5-3.2/100,000) and the crude prevalence was 36.1 per 100,000 inhabitants (95% CI: 34.9-37.3). There was a significant increase in Myasthenia Gravis prevalence from 2006 to 2016. Prevalence rates of all MG subgroups but thymoma-associated MG increased over the same period of time. CONCLUSIONS The incidence and prevalence of Myasthenia Gravis have increased over time in Sweden, and the rates are high in comparison with other countries.
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Affiliation(s)
- Elisabet Westerberg
- Department of NeuroscienceClinical NeurophysiologyUppsala UniversityUppsalaSweden
| | - Anna Rostedt Punga
- Department of NeuroscienceClinical NeurophysiologyUppsala UniversityUppsalaSweden
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12
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Cao M, Koneczny I, Vincent A. Myasthenia Gravis With Antibodies Against Muscle Specific Kinase: An Update on Clinical Features, Pathophysiology and Treatment. Front Mol Neurosci 2020; 13:159. [PMID: 32982689 PMCID: PMC7492727 DOI: 10.3389/fnmol.2020.00159] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2020] [Accepted: 08/03/2020] [Indexed: 12/24/2022] Open
Abstract
Muscle Specific Kinase myasthenia gravis (MuSK-MG) is an autoimmune disease that impairs neuromuscular transmission leading to generalized muscle weakness. Compared to the more common myasthenia gravis with antibodies against the acetylcholine receptor (AChR), MuSK-MG affects mainly the bulbar and respiratory muscles, with more frequent and severe myasthenic crises. Treatments are usually less effective with the need for prolonged, high doses of steroids and other immunosuppressants to control symptoms. Under physiological condition, MuSK regulates a phosphorylation cascade which is fundamental for the development and maintenance of postsynaptic AChR clusters at the neuromuscular junction (NMJ). Agrin, secreted by the motor nerve terminal into the synaptic cleft, binds to low density lipoprotein receptor-related protein 4 (LRP4) which activates MuSK. In MuSK-MG, monovalent MuSK-IgG4 autoantibodies block MuSK-LRP4 interaction preventing MuSK activation and leading to the dispersal of AChR clusters. Lower levels of divalent MuSK IgG1, 2, and 3 antibody subclasses are also present but their contribution to the pathogenesis of the disease remains controversial. This review aims to provide a detailed update on the epidemiological and clinical features of MuSK-MG, focusing on the pathophysiological mechanisms and the latest indications regarding the efficacy and safety of different treatment options.
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Affiliation(s)
- Michelangelo Cao
- Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, United Kingdom
| | - Inga Koneczny
- Division of Neuropathology and Neurochemistry, Department of Neurology, Medical University of Vienna, Vienna, Austria
| | - Angela Vincent
- Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, United Kingdom
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13
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Marino M, Basile U, Spagni G, Napodano C, Iorio R, Gulli F, Todi L, Provenzano C, Bartoccioni E, Evoli A. Long-Lasting Rituximab-Induced Reduction of Specific-But Not Total-IgG4 in MuSK-Positive Myasthenia Gravis. Front Immunol 2020; 11:613. [PMID: 32431692 PMCID: PMC7214629 DOI: 10.3389/fimmu.2020.00613] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Accepted: 03/17/2020] [Indexed: 12/17/2022] Open
Abstract
The use of rituximab (RTX), an anti-CD20 monoclonal antibody (Ab), in refractory myasthenia gravis (MG) is associated with a better response in patients with Abs to the muscle-specific tyrosine kinase (MuSK) than in other MG subgroups. Anti-MuSK Abs are mostly IgG4 with proven pathogenicity and positive correlation with clinical severity. The rapid and sustained response to RTX may be related to MuSK Ab production by short-lived Ab-secreting cells derived from specific CD20+ B cells. Here, we investigated the long-term effects of RTX in nine refractory MuSK-MG patients with a follow-up ranging from 17 months to 13 years. In patients' sera, we titrated MuSK-specific IgG (MuSK-IgG) and MuSK-IgG4, along with total IgG and IgG4 levels. Optimal response to RTX was defined as the achievement and maintenance of the status of minimal manifestations (MM)-or-better together with a ≥ 50% steroid reduction, withdrawal of immunosuppressants, and no need for plasma-exchange or intravenous immunoglobulin. After a course of RTX, eight patients improved, with optimal response in six, while only one patient did not respond. At baseline, MuSK-IgG and MuSK-IgG4 serum titers were positive in all patients, ranging from 2.15 to 49.5 nmol/L and from 0.33 to 46.2 nmol/L, respectively. MuSK Abs mostly consisted of IgG4 (range 63.80-98.86%). RTX administration was followed by a marked reduction of MuSK Abs at 2-7 months and at 12-30 months (p < 0.02 for MuSK-IgG and p < 0.01 for MuSK-IgG4). In patients with a longer follow-up, MuSK Ab titers remained suppressed, paralleling clinical response. In the patient who achieved long-term complete remission, MuSK-IgG4 was no longer detectable within 2 years, while MuSK-IgG remained positive at very low titers up to 10 years after RTX. In the patient who did not respond, MuSK-IgG and MuSK-IgG4 remained unchanged. In this patient series, total IgG and IgG4 transiently decreased (p < 0.05) at 2-7 months after RTX. The different trends of reduction between MuSK-IgG4 and total IgG4 after RTX support the view that short-lived Ab-secreting cells are the main producers of MuSK Abs. The ratio between short-lived Ab-secreting cells and long-lived plasma cells may influence the response to RTX, and B-cell severe depletion may reduce self-maintaining autoimmune reactivity.
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Affiliation(s)
- Mariapaola Marino
- Istituto di Patologia Generale, Università Cattolica del Sacro Cuore, Rome, Italy.,Fondazione Policlinico Universitario "A. Gemelli" IRCCS, Rome, Italy
| | - Umberto Basile
- Area Diagnostica di Laboratorio, Fondazione Policlinico Universitario "A. Gemelli" IRCCS, Rome, Italy
| | - Gregorio Spagni
- Istituto di Neurologia, Università Cattolica del Sacro Cuore, Rome, Italy.,Dipartimento di Neuroscienze, Fondazione Policlinico Universitario "A. Gemelli" IRCCS, Rome, Italy
| | - Cecilia Napodano
- Istituto di Medicina Interna, Università Cattolica del Sacro Cuore, Rome, Italy.,Area di Gastroenterologia e Oncologia Medica, Fondazione Policlinico Universitario "A. Gemelli" IRCCS, Rome, Italy
| | - Raffaele Iorio
- Dipartimento di Neuroscienze, Fondazione Policlinico Universitario "A. Gemelli" IRCCS, Rome, Italy
| | - Francesca Gulli
- Dipartimento di Medicina di Laboratorio, Ospedale Madre Giuseppina Vannini, Rome, Italy
| | - Laura Todi
- Istituto di Patologia Generale, Università Cattolica del Sacro Cuore, Rome, Italy.,Fondazione Policlinico Universitario "A. Gemelli" IRCCS, Rome, Italy
| | - Carlo Provenzano
- Istituto di Patologia Generale, Università Cattolica del Sacro Cuore, Rome, Italy.,Fondazione Policlinico Universitario "A. Gemelli" IRCCS, Rome, Italy
| | - Emanuela Bartoccioni
- Istituto di Patologia Generale, Università Cattolica del Sacro Cuore, Rome, Italy.,Fondazione Policlinico Universitario "A. Gemelli" IRCCS, Rome, Italy
| | - Amelia Evoli
- Istituto di Neurologia, Università Cattolica del Sacro Cuore, Rome, Italy.,Dipartimento di Neuroscienze, Fondazione Policlinico Universitario "A. Gemelli" IRCCS, Rome, Italy
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14
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Lazaridis K, Tzartos SJ. Autoantibody Specificities in Myasthenia Gravis; Implications for Improved Diagnostics and Therapeutics. Front Immunol 2020; 11:212. [PMID: 32117321 PMCID: PMC7033452 DOI: 10.3389/fimmu.2020.00212] [Citation(s) in RCA: 111] [Impact Index Per Article: 27.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2019] [Accepted: 01/27/2020] [Indexed: 12/13/2022] Open
Abstract
Myasthenia gravis (MG) is an autoimmune disease characterized by muscle weakness and fatiguability of skeletal muscles. It is an antibody-mediated disease, caused by autoantibodies targeting neuromuscular junction proteins. In the majority of patients (~85%) antibodies against the muscle acetylcholine receptor (AChR) are detected, while in 6% antibodies against the muscle-specific kinase (MuSK) are detected. In ~10% of MG patients no autoantibodies can be found with the classical diagnostics for AChR and MuSK antibodies (seronegative MG, SN-MG), making the improvement of methods for the detection of known autoantibodies or the discovery of novel antigenic targets imperative. Over the past years, using cell-based assays or improved highly sensitive immunoprecipitation assays, it has been possible to detect autoantibodies in previously SN-MG patients, including the identification of the low-density lipoprotein receptor-related protein 4 (LRP4) as a third MG autoantigen, as well as AChR and MuSK antibodies undetectable by conventional methods. Furthermore, antibodies against other extracellular or intracellular targets, such as titin, the ryanodine receptor, agrin, collagen Q, Kv1.4 potassium channels and cortactin have been found in some MG patients, which can be useful biomarkers. In addition to the improvement of diagnosis, the identification of the patients' autoantibody specificity is important for their stratification into respective subgroups, which can differ in terms of clinical manifestations, prognosis and most importantly their response to therapies. The knowledge of the autoantibody profile of MG patients would allow for a therapeutic strategy tailored to their MG subgroup. This is becoming especially relevant as there is increasing progress toward the development of antigen-specific therapies, targeting only the specific autoantibodies or immune cells involved in the autoimmune response, such as antigen-specific immunoadsorption, which have shown promising results. We will herein review the advances made by us and others toward development of more sensitive detection methods and the identification of new antibody targets in MG, and discuss their significance in MG diagnosis and therapy. Overall, the development of novel autoantibody assays is aiding in the more accurate diagnosis and classification of MG patients, supporting the development of advanced therapeutics and ultimately the improvement of disease management and patient quality of life.
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Affiliation(s)
| | - Socrates J Tzartos
- Department of Neurobiology, Hellenic Pasteur Institute, Athens, Greece.,Tzartos NeuroDiagnostics, Athens, Greece
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15
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Serological Immunoglobulin-Free Light Chain Profile in Myasthenia Gravis Patients. J Immunol Res 2018; 2018:9646209. [PMID: 29765992 PMCID: PMC5889870 DOI: 10.1155/2018/9646209] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Accepted: 01/29/2018] [Indexed: 12/12/2022] Open
Abstract
Background Serological levels of free immunoglobulin light chains (FLCs), produced in excess of heavy chains during synthesis of immunoglobulins by plasma cells, can be considered a direct marker of B cell activity in different systemic inflammatory-autoimmune conditions and may represent a useful predictor of rituximab (RTX) therapeutic efficacy, as reported for rheumatoid arthritis and systemic lupus erythematosus. Myasthenia gravis (MG) is an autoimmune disease of the neuromuscular junction with antibodies (abs) targeting the acetylcholine receptor (AChR) or the muscle-specific tyrosine kinase (MuSK), inducing muscle weakness and excessive fatigability. As MG course may be remarkably variable, we evaluated the possible use of FLCs as biomarkers of disease activity. Subjects and Methods We assessed FLC levels in 34 sera from 17 AChR-MG and from 13 MuSK-MG patients, in comparison with 20 sera from patients with systemic autoimmune rheumatic diseases and 18 from healthy blood donors, along with titers of specific auto-abs and IgG subclass distribution. Results We found a statistically significant increase in free κ chains in both AChR- and MuSK-MG patients, while free λ chain levels were increased only in AChR-MG. We also observed a significant reduction of both free κ and λ chains in 1/4 MuSK-MG patients along with specific abs titer, two months after RTX treatment. Conclusions From our data, FLCs appear to be a sensitive marker of B cell activation in MG. Further investigations are necessary to exploit their potential as reliable biomarkers of disease activity.
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16
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Evoli A, Alboini PE, Damato V, Iorio R, Provenzano C, Bartoccioni E, Marino M. Myasthenia gravis with antibodies to MuSK: an update. Ann N Y Acad Sci 2017; 1412:82-89. [PMID: 29266255 DOI: 10.1111/nyas.13518] [Citation(s) in RCA: 72] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Revised: 09/06/2017] [Accepted: 09/12/2017] [Indexed: 02/06/2023]
Abstract
Myasthenia gravis with antibodies to the muscle-specific tyrosine kinase (MuSK+ MG) is a rare disease with distinctive pathogenic mechanisms and clinical features. An acute onset and predominant bulbar muscle weakness are very common and highly suggestive of the disease. On the other hand, a more indolent course, atypical ocular presentation, and signs of cholinergic hyperactivity may complicate the diagnosis. Though MuSK+ MG is still a severe disease, over the years we have observed a steady reduction in the rate of respiratory crisis and a significant improvement in the clinical outcome, both likely related to earlier diagnosis and timely treatment. Despite the improved management, MuSK+ MG patients tend to remain dependent on long-term immunosuppressive treatment and may develop permanent disabling weakness. In uncontrolled studies, B cell depletion with rituximab proved effective in most patients with refractory disease, inducing prolonged clinical responses associated with a sustained reduction of serum antibody levels. Promising results from experimental studies and case reports suggest that both 3,4-diaminopyridine and albuterol may be effective as symptomatic agents.
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Affiliation(s)
- Amelia Evoli
- Institute of Neurology, Catholic University, Fondazione Policlinico Gemelli, Rome, Italy
| | - Paolo E Alboini
- Institute of Neurology, Catholic University, Fondazione Policlinico Gemelli, Rome, Italy
| | - Valentina Damato
- Institute of Neurology, Catholic University, Fondazione Policlinico Gemelli, Rome, Italy
| | - Raffaele Iorio
- Institute of Neurology, Catholic University, Fondazione Policlinico Gemelli, Rome, Italy
| | - Carlo Provenzano
- Institute of General Pathology, Catholic University, Fondazione Policlinico Gemelli, Rome, Italy
| | - Emanuela Bartoccioni
- Institute of General Pathology, Catholic University, Fondazione Policlinico Gemelli, Rome, Italy
| | - Mariapaola Marino
- Institute of General Pathology, Catholic University, Fondazione Policlinico Gemelli, Rome, Italy
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17
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Autoantibodies to Low-Density Lipoprotein Receptor-Related Protein 4 in Double Seronegative Myasthenia Gravis: A Systematic Review. Can J Neurol Sci 2017; 45:62-67. [DOI: 10.1017/cjn.2017.253] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
AbstractBackground: Myasthenia gravis (MG) is an autoimmune disorder of the neuromuscular junction in which a clinical diagnosis may be confirmed with serological testing. The most common autoantibodies used to support a diagnosis of MG are anti-acetylcholine receptor antibodies and anti-muscle-specific tyrosine kinase antibodies. In cases in which both of these autoantibodies are negative (termed double-seronegative [dSNMG]), other autoantibodies such as low-density lipoprotein receptor-related protein 4 (LRP4) may be used to aid in diagnosis. Methods: We have undertaken a systematic literature review to identify studies that have assessed the frequency of anti-LRP4 antibodies in dSNMG patients and the characteristics of anti-LRP4+ dSNMG patients (epidemiology, clinical features, electromyographic findings, or management). PubMed, EMBASE, Medline, and Scopus were searched on January 14, 2017, using the medical subject headings “myasthenia gravis” and “low-density lipoprotein receptor-related protein 4” or “LRP4.” Results: The initial search identified 367 articles. Fourteen publications met the inclusion criteria. There were ten cross-sectional research studies, three were case series, and one was a case report. The majority of studies were limited by small sample sizes of LRP4+ dSNMG. There has been a wide range of frequencies of anti-LRP4 antibodies detected in different MG patient populations, some involving different laboratory techniques. Conclusions: LRP4+ dSNMG is more likely than LRP4– dSNMG to have a younger onset of disease and occur in females. LRP4+ dSNMG most often is mild in severity and often involves isolated ocular weakness. It typically responds well to pyridostigmine or prednisone.
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18
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Verschuuren J, Strijbos E, Vincent A. Neuromuscular junction disorders. HANDBOOK OF CLINICAL NEUROLOGY 2017; 133:447-66. [PMID: 27112691 DOI: 10.1016/b978-0-444-63432-0.00024-4] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Diseases of the neuromuscular junction comprise a wide range of disorders. Antibodies, genetic mutations, specific drugs or toxins interfere with the number or function of one of the essential proteins that control signaling between the presynaptic nerve ending and the postsynaptic muscle membrane. Acquired autoimmune disorders of the neuromuscular junction are the most common and are described here. In myasthenia gravis, antibodies to acetylcholine receptors or to proteins involved in receptor clustering, particularly muscle-specific kinase, cause direct loss of acetylcholine receptors or interfere with the agrin-induced acetylcholine receptor clustering necessary for efficient neurotransmission. In the Lambert-Eaton myasthenic syndrome (LEMS), loss of the presynaptic voltage-gated calcium channels results in reduced release of the acetylcholine transmitter. The conditions are generally recognizable clinically and the diagnosis confirmed by serologic testing and electromyography. Screening for thymomas in myasthenia or small cell cancer in LEMS is important. Fortunately, a wide range of symptomatic treatments, immunosuppressive drugs, or other immunomodulating therapies is available. Future research is directed to understanding the pathogenesis, discovering new antigens, and trying to develop disease-specific treatments.
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Affiliation(s)
- Jan Verschuuren
- Department of Neurology, Leiden University Medical Centre, Leiden, The Netherlands.
| | - Ellen Strijbos
- Department of Neurology, Leiden University Medical Centre, Leiden, The Netherlands
| | - Angela Vincent
- Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, Oxford, UK
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19
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Koneczny I, Stevens JAA, De Rosa A, Huda S, Huijbers MG, Saxena A, Maestri M, Lazaridis K, Zisimopoulou P, Tzartos S, Verschuuren J, van der Maarel SM, van Damme P, De Baets MH, Molenaar PC, Vincent A, Ricciardi R, Martinez-Martinez P, Losen M. IgG4 autoantibodies against muscle-specific kinase undergo Fab-arm exchange in myasthenia gravis patients. J Autoimmun 2016; 77:104-115. [PMID: 27965060 DOI: 10.1016/j.jaut.2016.11.005] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Revised: 10/17/2016] [Accepted: 11/22/2016] [Indexed: 01/13/2023]
Abstract
Autoimmunity mediated by IgG4 subclass autoantibodies is an expanding field of research. Due to their structural characteristics a key feature of IgG4 antibodies is the ability to exchange Fab-arms with other, unrelated, IgG4 molecules, making the IgG4 molecule potentially monovalent for the specific antigen. However, whether those disease-associated antigen-specific IgG4 are mono- or divalent for their antigens is unknown. Myasthenia gravis (MG) with antibodies to muscle specific kinase (MuSK-MG) is a well-recognized disease in which the predominant pathogenic IgG4 antibody binds to extracellular epitopes on MuSK at the neuromuscular junction; this inhibits a pathway that clusters the acetylcholine (neurotransmitter) receptors and leads to failure of neuromuscular transmission. In vitro Fab-arm exchange-inducing conditions were applied to MuSK antibodies in sera, purified IgG4 and IgG1-3 sub-fractions. Solid-phase cross-linking assays were established to determine the extent of pre-existing and inducible Fab-arm exchange. Functional effects of the resulting populations of IgG4 antibodies were determined by measuring inhibition of agrin-induced AChR clustering in C2C12 cells. To confirm the results, κ/κ, λ/λ and hybrid κ/λ IgG4s were isolated and tested for MuSK antibodies. At least fifty percent of patients had IgG4, but not IgG1-3, MuSK antibodies that could undergo Fab-arm exchange in vitro under reducing conditions. Also MuSK antibodies were found in vivo that were divalent (monospecific for MuSK). Fab-arm exchange with normal human IgG4 did not prevent the inhibitory effect of serum derived MuSK antibodies on AChR clustering in C2C12 mouse myotubes. The results suggest that a considerable proportion of MuSK IgG4 could already be Fab-arm exchanged in vivo. This was confirmed by isolating endogenous IgG4 MuSK antibodies containing both κ and λ light chains, i.e. hybrid IgG4 molecules. These new findings demonstrate that Fab-arm exchanged antibodies are pathogenic.
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Affiliation(s)
- Inga Koneczny
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, Universiteitssingel 50, 6229 ER Maastricht, The Netherlands
| | - Jo A A Stevens
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, Universiteitssingel 50, 6229 ER Maastricht, The Netherlands
| | - Anna De Rosa
- Department of Clinical and Experimental Medicine, Neurology Unit, University of Pisa, Via Paradisa 2, 56124 Pisa, Italy
| | - Saif Huda
- Neurology Department, Nuffield Department of Clinical Neurosciences, West Wing, John Radcliffe Hospital, Oxford OX3 9DU, United Kingdom
| | - Maartje G Huijbers
- Department of Neurology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA Leiden, The Netherlands; Department of Human Genetics, Leiden University Medical Center, Albinusdreef 2, 2333 ZA Leiden, The Netherlands
| | - Abhishek Saxena
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, Universiteitssingel 50, 6229 ER Maastricht, The Netherlands
| | - Michelangelo Maestri
- Department of Clinical and Experimental Medicine, Neurology Unit, University of Pisa, Via Paradisa 2, 56124 Pisa, Italy
| | - Konstantinos Lazaridis
- Hellenic Pasteur Institute, 127 Vasilissis Sofias Avenue 115 21, Ampelokipi, Athens, Greece; Neurology Department, University Hospital, Herestraat 49, 3000 Leuven, Belgium
| | - Paraskevi Zisimopoulou
- Hellenic Pasteur Institute, 127 Vasilissis Sofias Avenue 115 21, Ampelokipi, Athens, Greece; Neurology Department, University Hospital, Herestraat 49, 3000 Leuven, Belgium
| | - Socrates Tzartos
- Hellenic Pasteur Institute, 127 Vasilissis Sofias Avenue 115 21, Ampelokipi, Athens, Greece; Neurology Department, University Hospital, Herestraat 49, 3000 Leuven, Belgium
| | - Jan Verschuuren
- Department of Neurology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA Leiden, The Netherlands
| | - Silvère M van der Maarel
- Department of Human Genetics, Leiden University Medical Center, Albinusdreef 2, 2333 ZA Leiden, The Netherlands
| | - Philip van Damme
- Neurology Department, University Hospital, Herestraat 49, 3000 Leuven, Belgium; KU Leuven - University of Leuven, Department of Neurosciences, VIB - Vesalius Research Center, Experimental Neurology - Laboratory of Neurobiology, Leuven, Belgium
| | - Marc H De Baets
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, Universiteitssingel 50, 6229 ER Maastricht, The Netherlands
| | - Peter C Molenaar
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, Universiteitssingel 50, 6229 ER Maastricht, The Netherlands
| | - Angela Vincent
- Neurology Department, Nuffield Department of Clinical Neurosciences, West Wing, John Radcliffe Hospital, Oxford OX3 9DU, United Kingdom
| | - Roberta Ricciardi
- Department of Clinical and Experimental Medicine, Neurology Unit, University of Pisa, Via Paradisa 2, 56124 Pisa, Italy
| | - Pilar Martinez-Martinez
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, Universiteitssingel 50, 6229 ER Maastricht, The Netherlands.
| | - Mario Losen
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, Universiteitssingel 50, 6229 ER Maastricht, The Netherlands.
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20
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Santos E, Coutinho E, Moreira I, Silva AM, Lopes D, Costa H, Silveira F, Nadais G, Morais H, Martins J, Branco MC, Veiga A, Silva RS, Ferreira A, Sousa F, Freijo M, Matos I, André R, Negrão L, Fraga C, Santos M, Sampaio M, Lopes C, Leite MI, Gonçalves G. Epidemiology of myasthenia gravis in Northern Portugal: Frequency estimates and clinical epidemiological distribution of cases. Muscle Nerve 2016; 54:413-21. [PMID: 26851892 DOI: 10.1002/mus.25068] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Revised: 01/25/2016] [Accepted: 02/01/2016] [Indexed: 12/22/2022]
Abstract
INTRODUCTION In this study we estimated the prevalence, incidence, and mortality of myasthenia gravis (MG) in northern Portugal and characterized the clinical features of the patients identified. METHODS We used 2 data sources: clinical records from the hospitals and pyridostigmine prescription registers. RESULTS On December 31, 2013, we estimated a point prevalence of 111.7 patients per million population. The highest prevalence was observed in the group >65 years of age, especially in men (288.1 per million). During 2013, we estimated an incidence rate of 6.3 per million per year. Among women, the incidence rate was highest in the 15-49-year age group; in men, incidence increased with age up to 22.1 per million in those >65 years old. The MG-related mortality rate was 0.5 per million. CONCLUSIONS These figures are in keeping with similar studies and emphasize the importance of diagnosis and management of MG in elderly populations. Muscle Nerve 54: 413-421, 2016.
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Affiliation(s)
- Ernestina Santos
- Neurology Department, Hospital Santo Antonio, Centro Hospitalar Porto, Porto, Portugal.,Unit for Multidisciplinary Research in Biomedicine, Instituto de Ciencias Biomedicas de Abel Salazar, Universidade do Porto, Porto, Portugal
| | - Ester Coutinho
- Nuffield Department of Clinical Neurosciences, Oxford University Hospitals, University of Oxford, UK
| | - Isabel Moreira
- Neurology Department, Hospital Santo Antonio, Centro Hospitalar Porto, Porto, Portugal
| | - Ana Martins Silva
- Neurology Department, Hospital Santo Antonio, Centro Hospitalar Porto, Porto, Portugal.,Unit for Multidisciplinary Research in Biomedicine, Instituto de Ciencias Biomedicas de Abel Salazar, Universidade do Porto, Porto, Portugal
| | - Dina Lopes
- Centro Hospitalar do Porto, Porto, Portugal
| | - Henrique Costa
- Neurology Department, Hospital Sao Joao, Porto, Portugal
| | | | - Goreti Nadais
- Neurology Department, Hospital Sao Joao, Porto, Portugal
| | - Hugo Morais
- Neurology Department, Centro Hospitalar de Vila Nova de Gaia e Espinho, Gaia, Portugal
| | - João Martins
- Neurology Department, Hospital Pedro Hispano, Matosinhos, Portugal
| | - Maria Ceu Branco
- Neurology Department, Hospital Pedro Hispano, Matosinhos, Portugal.,Neurology Department, Hospital de Sao Pedro, Centro Hospitalar do Trás-os-Montes e Alto Douro, Vila Real, Portugal
| | - Andreia Veiga
- Neurology Department, Hospital de Sao Pedro, Centro Hospitalar do Trás-os-Montes e Alto Douro, Vila Real, Portugal
| | - Rosa Santos Silva
- Neurology Department, Centro Hospitalar do Alto Minho, Viana do Castelo, Portugal
| | - Augusto Ferreira
- Neurology Department, Centro Hospitalar Entre Douro e Vouga, Feira, Portugal
| | - Filipa Sousa
- Neurology Department, Hospital de Braga, Braga, Portugal
| | - Marta Freijo
- Neurology Department, Centro Hospitalar do Nordeste, Mirandela, Portugal
| | - Ilda Matos
- Neurology Department, Centro Hospitalar do Nordeste, Mirandela, Portugal
| | - Rui André
- Neurology Department, Hospital de São Teotonio, Viseu, Portugal
| | - Luís Negrão
- Neurology Department, Centro Hospitalar Universitario de Coimbra, Coimbra, Portugal
| | - Carla Fraga
- Neurology Department, Centro Hospitalar do Vale do Sousa, Penafiel, Portugal
| | - Manuela Santos
- Neuropediatrics Department, Centro Materno Infantil Norte, Centro Hospitalar Porto, Porto, Portugal
| | - Mafalda Sampaio
- Neuropediatrics Department, Hospital de Sao Joao, Porto, Portugal
| | - Carlos Lopes
- Instituto de Ciencias Biomedicas Abel Salazar, Universidade do Porto, Porto, Portugal
| | - Maria Isabel Leite
- Nuffield Department of Clinical Neurosciences, Oxford University Hospitals, University of Oxford, UK
| | - Guilherme Gonçalves
- Unit for Multidisciplinary Research in Biomedicine, Instituto de Ciencias Biomedicas de Abel Salazar, Universidade do Porto, Porto, Portugal
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21
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Kamada M, Nakane S, Matsui N, Higuchi O, Sakai W, Fujita K, Izumi Y, Matsuo H, Kaji R. Ocular myasthenia gravis with anti‐muscle‐specific tyrosine kinase antibodies: Two new cases and a systematic literature review. ACTA ACUST UNITED AC 2016. [DOI: 10.1111/cen3.12296] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- Masaki Kamada
- Department of Neurology Institute of Health Bioscience Tokushima University Graduate School of Medicine Tokushima Japan
- Department of Neurological Intractable Disease Research Kagawa University School of Medicine Kagawa Japan
| | - Shunya Nakane
- Department of Clinical Research Nagasaki Kawatana Medical Center Nagasaki Japan
- Department of Neurology Nagasaki Kawatana Medical Center Nagasaki Japan
| | - Naoko Matsui
- Department of Neurology Institute of Health Bioscience Tokushima University Graduate School of Medicine Tokushima Japan
| | - Osamu Higuchi
- Department of Clinical Research Nagasaki Kawatana Medical Center Nagasaki Japan
| | - Waka Sakai
- Department of Neurology Institute of Health Bioscience Tokushima University Graduate School of Medicine Tokushima Japan
- Department of Neurology Nagasaki Kawatana Medical Center Nagasaki Japan
| | - Koji Fujita
- Department of Neurology Institute of Health Bioscience Tokushima University Graduate School of Medicine Tokushima Japan
| | - Yuishin Izumi
- Department of Neurology Institute of Health Bioscience Tokushima University Graduate School of Medicine Tokushima Japan
| | - Hidenori Matsuo
- Department of Neurology Nagasaki Kawatana Medical Center Nagasaki Japan
| | - Ryuji Kaji
- Department of Neurology Institute of Health Bioscience Tokushima University Graduate School of Medicine Tokushima Japan
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22
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Binks S, Vincent A, Palace J. Myasthenia gravis: a clinical-immunological update. J Neurol 2015; 263:826-34. [PMID: 26705120 PMCID: PMC4826656 DOI: 10.1007/s00415-015-7963-5] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Accepted: 10/06/2015] [Indexed: 12/13/2022]
Abstract
Myasthenia gravis (MG) is the archetypic disorder of both the neuromuscular junction and autoantibody-mediated disease. In most patients, IgG1-dominant antibodies to acetylcholine receptors cause fatigable weakness of skeletal muscles. In the rest, a variable proportion possesses antibodies to muscle-specific tyrosine kinase while the remainder of seronegative MG is being explained through cell-based assays using a receptor-clustering technique and, to a lesser extent, proposed new antigenic targets. The incidence and prevalence of MG are increasing, particularly in the elderly. New treatments are being developed, and results from the randomised controlled trial of thymectomy in non-thymomatous MG, due for release in early 2016, will be of particular clinical value. To help navigate an evidence base of varying quality, practising clinicians may consult new MG guidelines in the fields of pregnancy, ocular and generalised MG (GMG). This review focuses on updates in epidemiology, immunology, therapeutic and clinical aspects of GMG in adults.
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Affiliation(s)
- Sophie Binks
- Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford, OX3 9DU, UK
| | - Angela Vincent
- Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford, OX3 9DU, UK
| | - Jacqueline Palace
- Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford, OX3 9DU, UK.
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23
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Huijbers MG, Querol LA, Niks EH, Plomp JJ, van der Maarel SM, Graus F, Dalmau J, Illa I, Verschuuren JJ. The expanding field of IgG4-mediated neurological autoimmune disorders. Eur J Neurol 2015; 22:1151-61. [PMID: 26032110 DOI: 10.1111/ene.12758] [Citation(s) in RCA: 122] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2015] [Accepted: 04/27/2015] [Indexed: 12/13/2022]
Abstract
At least 13 different disease entities affecting the central nervous system, peripheral nervous system and connective tissue of the skin or kidneys are associated with immunoglobulin G4 (IgG4) immune reactivity. IgG4 has always been considered a benign, non-inflammatory subclass of IgG, in contrast to the well-known complement-activating pro-inflammatory IgG1 subclass. A comprehensive review of these IgG4 autoimmune disorders reveals striking similarities in epitope binding and human leukocyte antigen (HLA) associations. Mechanical interference of extracellular ligand-receptor interactions by the associated IgG4 antibodies seems to be the common/converging disease mechanism in these disorders.
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Affiliation(s)
- M G Huijbers
- Department of Neurology, Leiden University Medical Center, Leiden, The Netherlands.,Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - L A Querol
- Department of Neurology, Hospital Santa Creu I Sant Pau, Barcelona, Spain
| | - E H Niks
- Department of Neurology, Leiden University Medical Center, Leiden, The Netherlands
| | - J J Plomp
- Department of Neurology, Leiden University Medical Center, Leiden, The Netherlands
| | - S M van der Maarel
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - F Graus
- Department of Neurology, Hospital Santa Creu I Sant Pau, Barcelona, Spain
| | - J Dalmau
- Department of Neurology, Hospital Santa Creu I Sant Pau, Barcelona, Spain
| | - I Illa
- Department of Neurology, Hospital Santa Creu I Sant Pau, Barcelona, Spain
| | - J J Verschuuren
- Department of Neurology, Leiden University Medical Center, Leiden, The Netherlands
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24
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MuSK autoantibodies in myasthenia gravis detected by cell based assay--A multinational study. J Neuroimmunol 2015; 284:10-7. [PMID: 26025053 DOI: 10.1016/j.jneuroim.2015.04.015] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Revised: 04/21/2015] [Accepted: 04/24/2015] [Indexed: 12/21/2022]
Abstract
Seronegative myasthenia gravis (MG) presents a serious gap in MG diagnosis and understanding. We applied a cell based assay (CBA) for the detection of muscle specific kinase (MuSK) antibodies undetectable by radioimmunoassay. We tested 633 triple-seronegative MG patients' sera from 13 countries, detecting 13% as positive. MuSK antibodies were found, at significantly lower frequencies, in 1.9% of healthy controls and 5.1% of other neuroimmune disease patients, including multiple sclerosis and neuromyelitis optica. The clinical data of the newly diagnosed MuSK-MG patients are presented. 27% of ocular seronegative patients were MuSK antibody positive. Moreover, 23% had thymic hyperplasia suggesting that thymic abnormalities are more common than believed.
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25
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Kaltsatou A, Fotiou D, Tsiptsios D, Orologas A. Cognitive impairment as a central cholinergic deficit in patients with Myasthenia Gravis. BBA CLINICAL 2015; 3:299-303. [PMID: 26672759 PMCID: PMC4661582 DOI: 10.1016/j.bbacli.2015.04.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/24/2014] [Revised: 04/16/2015] [Accepted: 04/17/2015] [Indexed: 11/21/2022]
Abstract
Background The purpose of this study was to investigate with neurophysiological and neuropsychological methods such as pupillometry, cognitive test and Hamilton Depression Rating Scale (HAM-D) the hypothesis of Central Nervous System (CNS) cholinergic involvement in patients with Myasthenia Gravis (MG). Methods Thirty-two patients (32) with MG and a mean age of 51.1 ± 17.2 volunteered to participate in this investigation, while thirty-three (33) healthy subjects with a mean age of 50.2 ± 14.8 served as controls. All subjects underwent pupillometric measurements and performed the Wechsler Memory Scale (WMS) and HAM-D. The pupillometric indices studied were: 1) latency for the onset of constriction (T1), 2) maximum constriction velocity (VCmax) and 3) maximum constriction acceleration (ACmax). Results T1 was found significantly increased by 21.7% (p < 0.05) in MG patients as compared to healthy subjects. Conversely, VCmax and ACmax were significantly decreased in MG patients by 33.3% (p < 0.05) and 43.5% (p < 0.05) respectively, as opposed to healthy subjects. Additionally, MG patients showed significantly decreased score in WMS by 41.6% (p < 0.05) as compared to healthy controls. No significant difference was found for HAM-D between the two groups. Conclusions VCmax and ACmax are governed mainly by the action of the Parasympathetic Nervous System, through acetylcholine. The results of this study demonstrate that the CNS may be affected in MG and support the hypothesis that MG has central cholinergic effects manifested by cognitive dysfunction. Myasthenia Gravis has central cholinergic deficits manifested by cognitive dysfunction. The hypothesis of Central Nervous System cholinergic involvement was examined with pupillometry and cognitive tests. Central Cholinergic System and/or the iris sphincter smooth muscle might be affected in Myasthenia Gravis.
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26
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Plomp JJ, Morsch M, Phillips WD, Verschuuren JJGM. Electrophysiological analysis of neuromuscular synaptic function in myasthenia gravis patients and animal models. Exp Neurol 2015; 270:41-54. [PMID: 25620417 DOI: 10.1016/j.expneurol.2015.01.007] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Revised: 01/07/2015] [Accepted: 01/16/2015] [Indexed: 12/21/2022]
Abstract
Study of the electrophysiological function of the neuromuscular junction (NMJ) is instrumental in the understanding of the symptoms and pathophysiology of myasthenia gravis (MG), an autoimmune disorder characterized by fluctuating and fatigable muscle weakness. Most patients have autoantibodies to the acetylcholine receptor at the NMJ. However, in recent years autoantibodies to other crucial postsynaptic membrane proteins have been found in previously 'seronegative' MG patients. Electromyographical recording of compound and single-fibre muscle action potentials provides a crucial in vivo method to determine neuromuscular transmission failure while ex vivo (miniature) endplate potential recordings can reveal the precise synaptic impairment. Here we will review these electrophysiological methods used to assess NMJ function and discuss their application and typical results found in the diagnostic and experimental study of patients and animal models of the several forms of MG.
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Affiliation(s)
- Jaap J Plomp
- Department of Neurology, Leiden University Medical Centre, Leiden, The Netherlands.
| | - Marco Morsch
- Motor Neuron Disease Research Group, Macquarie University, Sydney, Australia
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27
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Evoli A, Iorio R. Characteristics of myasthenia gravis with antibodies to muscle-specific kinase and low-density lipoprotein-related receptor protein 4. ACTA ACUST UNITED AC 2015. [DOI: 10.1111/cen3.12173] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Amelia Evoli
- Institute of Neurology; Catholic University; Roma Italy
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28
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Duman O, Koken R, Baran RT, Haspolat S, Topaloglu H. Infantile anti-MuSK positive myasthenia gravis in a patient with autoimmune polyendocrinopathy type 3. Eur J Paediatr Neurol 2014; 18:526-8. [PMID: 24685514 DOI: 10.1016/j.ejpn.2014.02.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Revised: 02/02/2014] [Accepted: 02/23/2014] [Indexed: 11/24/2022]
Abstract
Myasthenia gravis (MG) is an autoimmune disorder caused by autoantibodies and related to the muscle nicotinic acetylcholine receptor (AChR) or muscle-specific tyrosine kinase (MuSK). Myasthenia gravis with anti-MuSK antibodies rarely occurs in children. The present article reports a childhood onset case of auto-immune MG with anti-MuSK antibodies, part of autoimmune polyglandular syndrome.
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Affiliation(s)
- Ozgur Duman
- Department of Pediatric Neurology, Akdeniz University Hospital, Antalya, Turkey.
| | - Resit Koken
- Department of Pediatric Neurology, Akdeniz University Hospital, Antalya, Turkey
| | - R Taner Baran
- Department of Pediatric Endocrinology, Akdeniz University Hospital, Antalya, Turkey
| | - Senay Haspolat
- Department of Pediatric Neurology, Akdeniz University Hospital, Antalya, Turkey
| | - Haluk Topaloglu
- Department of Pediatric Neurology, Hacettepe University Children's Hospital, Ankara, Turkey
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29
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Zhang B, Shen C, Bealmear B, Ragheb S, Xiong WC, Lewis RA, Lisak RP, Mei L. Autoantibodies to agrin in myasthenia gravis patients. PLoS One 2014; 9:e91816. [PMID: 24632822 PMCID: PMC3954737 DOI: 10.1371/journal.pone.0091816] [Citation(s) in RCA: 96] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2014] [Accepted: 02/02/2014] [Indexed: 11/19/2022] Open
Abstract
To determine if patients with myasthenia gravis (MG) have antibodies to agrin, a proteoglycan released by motor neurons and is critical for neuromuscular junction (NMJ) formation, we collected serum samples from 93 patients with MG with known status of antibodies to acetylcholine receptor (AChR), muscle specific kinase (MuSK) and lipoprotein-related 4 (LRP4) and samples from control subjects (healthy individuals and individuals with other diseases). Sera were assayed for antibodies to agrin. We found antibodies to agrin in 7 serum samples of MG patients. None of the 25 healthy controls and none of the 55 control neurological patients had agrin antibodies. Two of the four triple negative MG patients (i.e., no detectable AChR, MuSK or LRP4 antibodies, AChR-/MuSK-/LRP4-) had antibodies against agrin. In addition, agrin antibodies were detected in 5 out of 83 AChR+/MuSK-/LRP4- patients but were not found in the 6 patients with MuSK antibodies (AChR-/MuSK+/LRP4-). Sera from MG patients with agrin antibodies were able to recognize recombinant agrin in conditioned media and in transfected HEK293 cells. These sera also inhibited the agrin-induced MuSK phosphorylation and AChR clustering in muscle cells. Together, these observations indicate that agrin is another autoantigen in patients with MG and agrin autoantibodies may be pathogenic through inhibition of agrin/LRP4/MuSK signaling at the NMJ.
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Affiliation(s)
- Bin Zhang
- Department of Neuroscience and Regenerative Medicine and Department of Neurology, Medical College of Georgia, Georgia Regents University, Augusta, Georgia, United States of America
- Department of Physiology, Basic Medical School, Tongji Medical College, Huazhong University of Science & Technology, Wuhan, Hubei Province, P. R. China
| | - Chengyong Shen
- Department of Neuroscience and Regenerative Medicine and Department of Neurology, Medical College of Georgia, Georgia Regents University, Augusta, Georgia, United States of America
- Charlie Norwood VA Medical Center, Augusta, Georgia, United States of America
| | - Beverly Bealmear
- Department of Neurology, School of Medicine, Wayne State University, Detroit, Michigan, United States of America
| | - Samia Ragheb
- Department of Neurology, School of Medicine, Wayne State University, Detroit, Michigan, United States of America
- Department of Biomedical Sciences, Oakland University William Beaumont School of Medicine, Rochester, Michigan, United States of America
| | - Wen-Cheng Xiong
- Department of Neuroscience and Regenerative Medicine and Department of Neurology, Medical College of Georgia, Georgia Regents University, Augusta, Georgia, United States of America
- Charlie Norwood VA Medical Center, Augusta, Georgia, United States of America
| | - Richard A. Lewis
- Department of Neurology, School of Medicine, Wayne State University, Detroit, Michigan, United States of America
- Department of Neurology, Cedars-Sinai Medical Center, West Hollywood, California, United States of America
| | - Robert P. Lisak
- Department of Neurology, School of Medicine, Wayne State University, Detroit, Michigan, United States of America
- Department of Immunology and Microbiology, School of Medicine, Wayne State University, Detroit, Michigan, United States of America
| | - Lin Mei
- Department of Neuroscience and Regenerative Medicine and Department of Neurology, Medical College of Georgia, Georgia Regents University, Augusta, Georgia, United States of America
- Charlie Norwood VA Medical Center, Augusta, Georgia, United States of America
- * E-mail:
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30
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Yilmaz S, Gokben S, Serdaroglu G, Akcay A. Early-onset acquired myasthenia gravis secondary to anti-muscle-specific kinase autoantibodies. J Child Neurol 2014; 29:108-10. [PMID: 23234677 DOI: 10.1177/0883073812467689] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Autoimmune myasthenia gravis is rarely seen during infancy. Similar to adults, 85% to 90% of generalized pediatric myasthenia gravis cases have acetylcholine receptor antibodies. Approximately 30% of the remaining cases have antibodies against muscle-specific kinase. Information on the clinical course, treatment alternatives, and prognosis of pediatric muscle-specific kinase antibody-positive myasthenia gravis is limited because of the small number of cases. Here, we present a 14-month-old girl with muscle-specific kinase antibody-positive myasthenia gravis as one of the youngest patients described so far in the literature.
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Affiliation(s)
- Sanem Yilmaz
- 1Department of Pediatrics, Division of Child Neurology, Ege University Faculty of Medicine, Izmir, Turkey
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Skjei KL, Lennon VA, Kuntz NL. Muscle specific kinase autoimmune myasthenia gravis in children: a case series. Neuromuscul Disord 2013; 23:874-82. [PMID: 24012245 DOI: 10.1016/j.nmd.2013.07.010] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2012] [Revised: 07/25/2013] [Accepted: 07/29/2013] [Indexed: 11/17/2022]
Abstract
We report clinical, neurophysiological and autoantibody profiles of 9 children presenting with fatigable weakness and MuSK autoantibody seropositivity. Eight were female, 3 were black; median onset age was 8 years. Diplopia or bulbar dysfunction were common presenting symptoms. Half of the patients experienced moderate to severe weakness of bulbar, facial and respiratory muscles (including exacerbations requiring mechanical ventilation). Muscle AChR antibodies were detected transiently in 2 patients but no other autoantibodies were detected. Clinical response to treatment was variable and incomplete. No thymic abnormalities were noted by CT or pathologically (3 underwent thymectomy). Electromyographic (EMG) abnormalities (decrement of compound muscle action potential amplitude during slow repetitive nerve stimulation and variation in individual motor unit potentials) were limited to clinically weak muscles. Single fiber EMG demonstrated abnormalities in an asymptomatic muscle in the single patient studied. As in adults, MuSK autoimmune MG presents more commonly in females, and weakness preferentially affects bulbar, facial and respiratory muscles. Morbidity is significant and responses to standard therapies are variable and incomplete. Neurophysiological confirmation is more challenging in children because testing of weak muscles (cranial nerve-innervated and respiratory) may require moderate sedation and monitoring.
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Affiliation(s)
- Karen L Skjei
- Department of Pediatrics, University of Louisville, Louisville, KY, USA
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Mechanisms associated with the pathogenicity of antibodies against muscle-specific kinase in myasthenia gravis. Autoimmun Rev 2013; 12:912-7. [DOI: 10.1016/j.autrev.2013.03.005] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/12/2013] [Indexed: 12/27/2022]
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MuSK-Ab positive myasthenia: not always grave. J Neurol Sci 2013; 331:150-1. [PMID: 23706725 DOI: 10.1016/j.jns.2013.05.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2013] [Revised: 04/25/2013] [Accepted: 05/01/2013] [Indexed: 11/22/2022]
Abstract
Antibodies (Abs) to muscle-specific tyrosine kinase (MuSK) are detected in approximately 40% of generalized acetylcholine receptor antibody-negative myasthenia gravis (MG). Anti-MuSK Abs are nearly always associated with generalized symptoms, with prevalent involvement of craniobulbar, cervical and respiratory muscles and with a striking preponderance in women. The typical course of MuSK-MG is acute onset, rapid progression, brittle course in the first years, early respiratory crises and unprovoked relapses in spite of high-dose immunosuppression. Patients often require long-term management with multiple immunosuppressive (IS) agents and many of them remain dependent on IS treatment. The majority of anti-MuSK Abs are of the non-complement-binding IgG4 subclass. We report the case of a Greek female MuSK-MG patient with typical phenotype but clearly atypical clinical course during 12 years of follow-up. The patient received only corticosteroid treatment for one year and showed mild and stable MG symptoms under no treatment for the rest of the observation period, except for postpartum mild and short-lived exacerbation. In mildly symptomatic stable state, anti-MuSK Abs were of the IgG4 subclass and no other immunological peculiarity was detected.
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Plomp JJ, Huijbers MG, van der Maarel SM, Verschuuren JJ. Pathogenic IgG4 subclass autoantibodies in MuSK myasthenia gravis. Ann N Y Acad Sci 2012; 1275:114-22. [DOI: 10.1111/j.1749-6632.2012.06808.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Poulas K, Koutsouraki E, Kordas G, Kokla A, Tzartos SJ. Anti-MuSK- and anti-AChR-positive myasthenia gravis induced by d-penicillamine. J Neuroimmunol 2012; 250:94-8. [DOI: 10.1016/j.jneuroim.2012.05.011] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2011] [Revised: 03/17/2012] [Accepted: 05/16/2012] [Indexed: 10/28/2022]
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Klooster R, Plomp JJ, Huijbers MG, Niks EH, Straasheijm KR, Detmers FJ, Hermans PW, Sleijpen K, Verrips A, Losen M, Martinez-Martinez P, De Baets MH, van der Maarel SM, Verschuuren JJ. Muscle-specific kinase myasthenia gravis IgG4 autoantibodies cause severe neuromuscular junction dysfunction in mice. Brain 2012; 135:1081-101. [DOI: 10.1093/brain/aws025] [Citation(s) in RCA: 158] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
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Trakas N, Zisimopoulou P, Tzartos SJ. Development of a highly sensitive diagnostic assay for muscle-specific tyrosine kinase (MuSK) autoantibodies in myasthenia gravis. J Neuroimmunol 2011; 240-241:79-86. [DOI: 10.1016/j.jneuroim.2011.09.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2011] [Accepted: 09/16/2011] [Indexed: 10/16/2022]
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Abstract
PURPOSE OF REVIEW This review discusses recent studies on myasthenia gravis with onset in childhood (juvenile myasthenia gravis) and neonatal myasthenia gravis. RECENT FINDINGS The occurrence of myasthenia gravis in childhood is strongly influenced by genetic and environmental factors. Juvenile myasthenia gravis is associated with antibodies to the acetylcholine receptor (AChR) in most patients. Thymoma is rare, but often malignant in children. The frequency of juvenile myasthenia gravis with antibodies to the muscle-specific kinase (MuSK) varies markedly in different countries; some distinct features have been described. Management of juvenile myasthenia gravis does not differ, on the whole, from that of adult myasthenia gravis. Timing of thymectomy in young children is still controversial. Maternal antifetal type AChR antibodies can cause persistent focal weakness in the offspring, while neonatal myasthenia gravis associated with MuSK antibodies is often a severe and protracted albeit transient disease. SUMMARY Juvenile myasthenia gravis, like its adult-onset counterpart, is a heterogeneous disease. Clinical presentation is influenced by antibody status, ethnicity and age of onset. Treatment is very effective, but guidelines and controlled trials are needed.The risk for neonatal myasthenia gravis appears to be markedly influenced by maternal antibody subclass and antigen specificity. Adequate treatment in mothers can reduce both frequency and severity of neonatal disease.
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Neurology in the European Journal of Neurology. Eur J Neurol 2010. [DOI: 10.1111/j.1468-1331.2010.03248.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Current world literature. Curr Opin Ophthalmol 2010; 21:495-501. [PMID: 20948381 DOI: 10.1097/icu.0b013e3283402a34] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Carr AS, Cardwell CR, McCarron PO, McConville J. A systematic review of population based epidemiological studies in Myasthenia Gravis. BMC Neurol 2010; 10:46. [PMID: 20565885 PMCID: PMC2905354 DOI: 10.1186/1471-2377-10-46] [Citation(s) in RCA: 394] [Impact Index Per Article: 28.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2009] [Accepted: 06/18/2010] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The aim was to collate all myasthenia gravis (MG) epidemiological studies including AChR MG and MuSK MG specific studies. To synthesize data on incidence rate (IR), prevalence rate (PR) and mortality rate (MR) of the condition and investigate the influence of environmental and technical factors on any trends or variation observed. METHODS Studies were identified using multiple sources and meta-analysis performed to calculate pooled estimates for IR, PR and MR. RESULTS 55 studies performed between 1950 and 2007 were included, representing 1.7 billion population-years. For All MG estimated pooled IR (eIR): 5.3 per million person-years (C.I.:4.4, 6.1), range: 1.7 to 21.3; estimated pooled PR: 77.7 per million persons (C.I.:64.0, 94.3), range 15 to 179; MR range 0.1 to 0.9 per millions person-years. AChR MG eIR: 7.3 (C.I.:5.5, 7.8), range: 4.3 to 18.0; MuSK MG IR range: 0.1 to 0.32. However marked variation persisted between populations studied with similar methodology and in similar areas. CONCLUSIONS We report marked variation in observed frequencies of MG. We show evidence of increasing frequency of MG with year of study and improved study quality. This probably reflects improved case ascertainment. But other factors must also influence disease onset resulting in the observed variation in IR across geographically and genetically similar populations.
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Affiliation(s)
- Aisling S Carr
- Department of Neurology, Royal Victoria Hospital, Belfast, Northern Ireland, UK
| | - Chris R Cardwell
- Department of Epidemiology and Medical Statistics, Queens University, Belfast, Northern Ireland, UK
| | - Peter O McCarron
- Department of Epidemiology and Medical Statistics, Queens University, Belfast, Northern Ireland, UK
| | - John McConville
- Department of Neurology, Royal Victoria Hospital, Belfast, Northern Ireland, UK
- Department of Neurology, Ulster Hospital, Dundonald, Northern Ireland, UK
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