1
|
Ziaadini B, Ghaderi Yazdi B, Dirandeh E, Boostani R, Karimi N, Panahi A, Kariminejad A, Fadaee M, Ahangari F, Nafissi S. DOK7 congenital myasthenic syndrome: case series and review of literature. BMC Neurol 2024; 24:211. [PMID: 38907197 PMCID: PMC11191154 DOI: 10.1186/s12883-024-03713-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Accepted: 06/05/2024] [Indexed: 06/23/2024] Open
Abstract
BACKGROUND Congenital myasthenic syndromes (CMS) are among the most challenging differential diagnoses in the neuromuscular domain, consisting of diverse genotypes and phenotypes. A mutation in the Docking Protein 7 (Dok-7) is a common cause of CMS. DOK7 CMS requires different treatment than other CMS types. Regarding DOK7's special considerations and challenges ahead of neurologists, we describe seven DOK7 patients and evaluate their response to treatment. METHODS The authors visited these patients in the neuromuscular clinics of Tehran and Kerman Universities of Medical Sciences Hospitals. They diagnosed these patients based on clinical findings and neurophysiological studies, which Whole Exome Sequencing confirmed. For each patient, we tried unique medications and recorded the clinical response. RESULTS The symptoms started from birth to as late as the age of 33, with the mean age of onset being 12.5. Common symptoms were: Limb-girdle weakness in 6, fluctuating symptoms in 5, ptosis in 4, bifacial weakness in 3, reduced extraocular movement in 3, bulbar symptoms in 2 and dyspnea in 2 3-Hz RNS was decremental in 5 out of 6 patients. Salbutamol was the most effective. c.1124_1127dupTGCC is the most common variant; three patients had this variant. CONCLUSION We strongly recommend that neurologists consider CMS in patients with these symptoms and a similar familial history. We recommend prescribing salbutamol as the first-choice treatment option for DOK7 patients.
Collapse
Affiliation(s)
- Bentolhoda Ziaadini
- Neurology Research Center, Kerman University of Medical Sciences, Kerman, Iran
| | - Bardyia Ghaderi Yazdi
- Neuromuscular Research Center, Shariati Hospital, Tehran University of Medical Sciences, Shariati Hospital, North Karegar St, Tehran, 14117-13135, Iran
- Department of Neurology, Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran
| | - Elham Dirandeh
- Clinical Research Development Unit, Kowsar Educational, Research and Therapeutic Hospital, Semnan University of Medical Sciences, Semnan, Iran
| | - Reza Boostani
- Department of Neurology, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Narges Karimi
- Department of Neurology, School of Medicine, Immunogenetics Research Center, Toxoplasmosis Research Center, Clinical Research Development Unit of Bou Ali Sina Hospital, Mazandaran University of Medical Sciences, Sari, Iran
| | - Akram Panahi
- Neuromuscular Research Center, Shariati Hospital, Tehran University of Medical Sciences, Shariati Hospital, North Karegar St, Tehran, 14117-13135, Iran
- Department of Neurology, Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran
| | | | - Mahsa Fadaee
- Kariminejad-Najmabadi Pathology & Genetics Center, Tehran, Iran
| | | | - Shahriar Nafissi
- Neuromuscular Research Center, Shariati Hospital, Tehran University of Medical Sciences, Shariati Hospital, North Karegar St, Tehran, 14117-13135, Iran.
- Department of Neurology, Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran.
| |
Collapse
|
2
|
Turgut GT, Altunoglu U, Gulec C, Sarac Sivrikoz T, Kalaycı T, Toksoy G, Avcı Ş, Yıldırım BT, Sayın GY, Kalelioglu IH, Karaman B, Has R, Başaran S, Yuksel A, Kayserili H, Uyguner ZO. Clinical and molecular characteristics of 26 fetuses with lethal multiple congenital contractures. Clin Genet 2024; 105:596-610. [PMID: 38278647 DOI: 10.1111/cge.14490] [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: 11/16/2023] [Revised: 01/03/2024] [Accepted: 01/15/2024] [Indexed: 01/28/2024]
Abstract
Multiple congenital contractures (MCC) due to fetal akinesia manifest across a broad spectrum of diseases, ranging from mild distal arthrogryposis to lethal fetal akinesia deformation sequence. We hereby present a series of 26 fetuses displaying severe MCC phenotypes from 18 families and describe detailed prenatal ultrasound findings, postmortem clinical evaluations, and genetic investigations. Most common prenatal findings were abnormal facial profile (65%), central nervous system abnormalities (62%), polyhydramnios (50%), increased nuchal translucency (50%), and fetal hydrops (35%). Postmortem examinations unveiled additional anomalies including facial dysmorphisms, dysplastic skeletal changes, ichthyosis, multiple pterygia, and myopathy, allowing preliminary diagnosis of particular Mendelian disorders in multiple patients. Evaluation of the parents revealed maternal grip myotonia in one family. By exome sequencing and targeted testing, we identified causative variants in ACTC1, CHST14, COG6, DMPK, DOK7, HSPG2, KLHL7, KLHL40, KIAA1109, NEB, PSAT1, RAPSN, USP14, and WASHC5 in 15 families, and one patient with a plausible diagnosis associated with biallelic NEB variants. Three patients received a dual diagnosis. Pathogenic alterations in newly discovered genes or in previously known genes recently linked to new MCC phenotypes were observed in 44% of the cohort. Our results provide new insights into the clinical and molecular landscape of lethal MCC phenotypes.
Collapse
Affiliation(s)
- Gozde Tutku Turgut
- Department of Medical Genetics, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey
| | - Umut Altunoglu
- Department of Medical Genetics, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey
- Department of Medical Genetics, Koç University School of Medicine (KUSoM), Istanbul, Turkey
| | - Cagri Gulec
- Department of Medical Genetics, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey
| | - Tugba Sarac Sivrikoz
- Division of Perinatology, Department of Obstetrics and Gynecology, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey
| | - Tuğba Kalaycı
- Department of Medical Genetics, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey
| | - Guven Toksoy
- Department of Medical Genetics, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey
| | - Şahin Avcı
- Department of Medical Genetics, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey
- Department of Medical Genetics, Koç University School of Medicine (KUSoM), Istanbul, Turkey
| | - Behiye Tuğçe Yıldırım
- Department of Medical Genetics, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey
| | - Gözde Yeşil Sayın
- Department of Medical Genetics, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey
| | - Ibrahim Halil Kalelioglu
- Division of Perinatology, Department of Obstetrics and Gynecology, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey
| | - Birsen Karaman
- Department of Medical Genetics, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey
- Department of Pediatric Basic Sciences, Institute of Child Health, Istanbul University, Istanbul, Turkey
| | - Recep Has
- Division of Perinatology, Department of Obstetrics and Gynecology, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey
| | - Seher Başaran
- Department of Medical Genetics, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey
| | - Atil Yuksel
- Division of Perinatology, Department of Obstetrics and Gynecology, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey
| | - Hülya Kayserili
- Department of Medical Genetics, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey
- Department of Medical Genetics, Koç University School of Medicine (KUSoM), Istanbul, Turkey
| | - Zehra Oya Uyguner
- Department of Medical Genetics, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey
| |
Collapse
|
3
|
Cossins J, Kozma I, Canzonetta C, Hawkins A, Beeson D, Sepulveda P, Dong Y. Dose escalation pre-clinical trial of novel DOK7-AAV in mouse model of DOK7 congenital myasthenia. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.09.579626. [PMID: 38405691 PMCID: PMC10888934 DOI: 10.1101/2024.02.09.579626] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/27/2024]
Abstract
Congenital myasthenic syndromes (CMS) are a group of inherited disorders characterised by defective neuromuscular transmission and fatigable muscle weakness. Mutations in DOK7 , a gene encoding a post-synaptic protein crucial in the formation and stabilisation of the neuromuscular junction (NMJ), rank among the leading three prevalent causes of CMS in diverse populations globally. The majority of DOK7 CMS patients experience varying degrees of disability despite receiving optimised treatment, necessitating the development of improved therapeutic approaches. Here we executed a dose escalation pre-clinical trial using a DOK7-CMS mouse model to assess the efficacy of Amp-101, an innovative AAV gene replacement therapy. Amp-101 is based on AAVrh74 and contains human DOK7 cDNA under the control of a muscle-restricted promoter. We show that at doses 6x10 13 vg/kg and 1x10 14 vg/kg, Amp-101 generated enlarged NMJs and rescued the very severe phenotype of the model. Treated mice became at least as strong as WT littermates and the diaphragm and tibialis anterior muscles displayed robust expression of DOK7. This data suggests that Amp-101 is a promising candidate to move forward to clinic trials.
Collapse
|
4
|
Salih MA. The Meryon Lecture at the 24th annual meeting of the Meryon Society, St. Anne's College, Oxford, UK, 15th July 2022: Neuromuscular diseases in the Arab population. Neuromuscul Disord 2023; 33:792-799. [PMID: 37679229 DOI: 10.1016/j.nmd.2023.08.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/09/2023]
Affiliation(s)
- Mustafa A Salih
- Consultant Pediatric Neurologist, Health Sector, King Abdulaziz City for Science and Technology, Riyadh 11442, Saudi Arabia.
| |
Collapse
|
5
|
Mazzaro A, Vita V, Ronfini M, Casola I, Klein A, Dobrowolny G, Sorarù G, Musarò A, Mongillo M, Zaglia T. Sympathetic neuropathology is revealed in muscles affected by amyotrophic lateral sclerosis. Front Physiol 2023; 14:1165811. [PMID: 37250128 PMCID: PMC10213213 DOI: 10.3389/fphys.2023.1165811] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Accepted: 04/14/2023] [Indexed: 05/31/2023] Open
Abstract
Rationale: The anatomical substrate of skeletal muscle autonomic innervation has remained underappreciated since it was described many decades ago. As such, the structural and functional features of muscle sympathetic innervation are largely undetermined in both physiology and pathology, mainly due to methodological limitations in the histopathological analysis of small neuronal fibers in tissue samples. Amyotrophic lateral sclerosis (ALS) is a fatal neuromuscular disease which mainly targets motor neurons, and despite autonomic symptoms occurring in a significant fraction of patients, peripheral sympathetic neurons (SNs) are generally considered unaffected and, as such, poorly studied. Purpose: In this research, we compared sympathetic innervation of normal and ALS muscles, through structural analysis of the sympathetic network in human and murine tissue samples. Methods and Results: We first refined tissue processing to circumvent methodological limitations interfering with the detection of muscle sympathetic innervation. The optimized "Neuro Detection Protocol" (NDP) was validated in human muscle biopsies, demonstrating that SNs innervate, at high density, both blood vessels and skeletal myofibers, independent of the fiber metabolic type. Subsequently, NDP was exploited to analyze sympathetic innervation in muscles of SOD1G93A mice, a preclinical ALS model. Our data show that ALS murine muscles display SN denervation, which has already initiated at the early disease stage and worsened during aging. SN degeneration was also observed in muscles of MLC/SOD1G93A mice, with muscle specific expression of the SOD1G93A mutant gene. Notably, similar alterations in SNs were observed in muscle biopsies from an ALS patient, carrying the SOD1G93A mutation. Conclusion: We set up a protocol for the analysis of murine and, more importantly, human muscle sympathetic innervation. Our results indicate that SNs are additional cell types compromised in ALS and suggest that dysfunctional SOD1G93A muscles affect their sympathetic innervation.
Collapse
Affiliation(s)
- Antonio Mazzaro
- Department of Cardiac, Thoracic, Vascular Sciences and Public Health, University of Padua, Padua, Italy
- Veneto Institute of Molecular Medicine, Padua, Italy
| | - Veronica Vita
- Department of Cardiac, Thoracic, Vascular Sciences and Public Health, University of Padua, Padua, Italy
- Veneto Institute of Molecular Medicine, Padua, Italy
| | - Marco Ronfini
- Veneto Institute of Molecular Medicine, Padua, Italy
- Department of Biomedical Sciences, University of Padua, Padua, Italy
| | - Irene Casola
- Laboratory Affiliated to Institute Pasteur Italia-Fondazione Cenci Bolognetti, DAHFMO-Unit of Histology and Medical Embryology, Sapienza University of Rome, Rome, Italy
| | - Arianna Klein
- Veneto Institute of Molecular Medicine, Padua, Italy
| | - Gabriella Dobrowolny
- Laboratory Affiliated to Institute Pasteur Italia-Fondazione Cenci Bolognetti, DAHFMO-Unit of Histology and Medical Embryology, Sapienza University of Rome, Rome, Italy
| | - Gianni Sorarù
- Department of Neuroscience, Azienda Ospedaliera di Padova, Padua, Italy
| | - Antonio Musarò
- Laboratory Affiliated to Institute Pasteur Italia-Fondazione Cenci Bolognetti, DAHFMO-Unit of Histology and Medical Embryology, Sapienza University of Rome, Rome, Italy
- Scuola Superiore di Studi Avanzati Sapienza (SSAS), Sapienza University of Rome, Rome, Italy
| | - Marco Mongillo
- Veneto Institute of Molecular Medicine, Padua, Italy
- Department of Biomedical Sciences, University of Padua, Padua, Italy
- CNR Institute of Neuroscience, Padua, Italy
- CIR-MYO Myology Center, University of Padua, Padua, Italy
| | - Tania Zaglia
- Veneto Institute of Molecular Medicine, Padua, Italy
- Department of Biomedical Sciences, University of Padua, Padua, Italy
- CIR-MYO Myology Center, University of Padua, Padua, Italy
| |
Collapse
|
6
|
Mendpara V, Bethanabotla S, Yadav M, Kanisetti V, Singh G, Das A, Sahu S, Patel H. When Breathing Becomes a Challenge: A Case of Congenital Myasthenia Gravis in an Indian Neonate With a DOK-7 Gene Mutation. Cureus 2023; 15:e38842. [PMID: 37303354 PMCID: PMC10256249 DOI: 10.7759/cureus.38842] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/10/2023] [Indexed: 06/13/2023] Open
Abstract
A rare neuromuscular condition known as congenital myasthenia gravis (CMG) affects some people from birth or very soon after. It results in fatigue and muscle weakness because of genetic abnormalities that interfere with the neuromuscular junction's ability to function, where the nerves and muscles connect. Even among those who have the same genetic mutation, the severity of CMG symptoms might differ considerably. The most typical signs of CMG include eyelid drooping, breathing issues, muscle weakness and weariness, and difficulties swallowing. Clinical examinations, neurophysiologic tests, and genetic analyses are frequently combined to make the diagnosis of CMG. Although there is no known treatment for CMG, many patients may control their symptoms and lead relatively normal lives with the right care. A newborn with CMG due to a DOK-7 gene mutation is described in this article, along with its very early onset. The DOK-7 mutation is a rare variant in the Indian population that causes CMG and usually manifests as 'limb girdle' weakness. However, due to muscle weakness, the neonate in this case developed severe respiratory distress and later died despite rigorous life-saving measures.
Collapse
Affiliation(s)
- Vaidehi Mendpara
- Medicine and Surgery, Pediatrics, Government Medical College Surat, Surat, IND
| | | | - Megha Yadav
- Medicine and Surgery, Maharani Laxmi Bai Medical College, Jhansi, IND
| | | | - Gurpreet Singh
- Medicine, Government Medical College and Hospital, Amritsar, IND
| | - Abhirami Das
- Internal Medicine, Rajiv Gandhi Medical College, Thane, IND
| | - Sweta Sahu
- Surgery, Jagadguru Jayadeva Murugarajendra (JJM) Medical College, Davanagere, IND
| | - Hitesh Patel
- Pediatrics and Child Health, Government Medical College and Hospital, Surat, IND
| |
Collapse
|
7
|
Ohno K, Ohkawara B, Shen XM, Selcen D, Engel AG. Clinical and Pathologic Features of Congenital Myasthenic Syndromes Caused by 35 Genes-A Comprehensive Review. Int J Mol Sci 2023; 24:ijms24043730. [PMID: 36835142 PMCID: PMC9961056 DOI: 10.3390/ijms24043730] [Citation(s) in RCA: 36] [Impact Index Per Article: 36.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2023] [Revised: 02/09/2023] [Accepted: 02/09/2023] [Indexed: 02/16/2023] Open
Abstract
Congenital myasthenic syndromes (CMS) are a heterogeneous group of disorders characterized by impaired neuromuscular signal transmission due to germline pathogenic variants in genes expressed at the neuromuscular junction (NMJ). A total of 35 genes have been reported in CMS (AGRN, ALG14, ALG2, CHAT, CHD8, CHRNA1, CHRNB1, CHRND, CHRNE, CHRNG, COL13A1, COLQ, DOK7, DPAGT1, GFPT1, GMPPB, LAMA5, LAMB2, LRP4, MUSK, MYO9A, PLEC, PREPL, PURA, RAPSN, RPH3A, SCN4A, SLC18A3, SLC25A1, SLC5A7, SNAP25, SYT2, TOR1AIP1, UNC13A, VAMP1). The 35 genes can be classified into 14 groups according to the pathomechanical, clinical, and therapeutic features of CMS patients. Measurement of compound muscle action potentials elicited by repetitive nerve stimulation is required to diagnose CMS. Clinical and electrophysiological features are not sufficient to identify a defective molecule, and genetic studies are always required for accurate diagnosis. From a pharmacological point of view, cholinesterase inhibitors are effective in most groups of CMS, but are contraindicated in some groups of CMS. Similarly, ephedrine, salbutamol (albuterol), amifampridine are effective in most but not all groups of CMS. This review extensively covers pathomechanical and clinical features of CMS by citing 442 relevant articles.
Collapse
Affiliation(s)
- Kinji Ohno
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
- Correspondence: (K.O.); (A.G.E.)
| | - Bisei Ohkawara
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Xin-Ming Shen
- Department of Neurology and Neuromuscular Research Laboratory, Mayo Clinic, Rochester, MN 55905, USA
| | - Duygu Selcen
- Department of Neurology and Neuromuscular Research Laboratory, Mayo Clinic, Rochester, MN 55905, USA
| | - Andrew G. Engel
- Department of Neurology and Neuromuscular Research Laboratory, Mayo Clinic, Rochester, MN 55905, USA
- Correspondence: (K.O.); (A.G.E.)
| |
Collapse
|
8
|
Shao S, Shi G, Bi FF, Huang K. Pharmacological Treatments for Congenital Myasthenic Syndromes Caused by COLQ Mutations. Curr Neuropharmacol 2023; 21:1594-1605. [PMID: 36703579 PMCID: PMC10472815 DOI: 10.2174/1570159x21666230126145652] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2022] [Revised: 09/30/2022] [Accepted: 11/18/2022] [Indexed: 01/28/2023] Open
Abstract
BACKGROUND Congenital myasthenic syndromes (CMS) refer to a series of inherited disorders caused by defects in various proteins. Mutation in the collagen-like tail subunit of asymmetric acetylcholinesterase (COLQ) is the second-most common cause of CMS. However, data on pharmacological treatments are limited. OBJECTIVE In this study, we reviewed related reports to determine the most appropriate pharmacological strategy for CMS caused by COLQ mutations. A literature review and meta-analysis were also performed. PubMed, MEDLINE, Web of Science, and Cochrane Library databases were searched to identify studies published in English before July 22, 2022. RESULTS A total of 42 studies including 164 patients with CMS due to 72 different COLQ mutations were selected for evaluation. Most studies were case reports, and none were randomized clinical trials. Our meta-analysis revealed evidence that β-adrenergic agonists, including salbutamol and ephedrine, can be used as first-line pharmacological treatments for CMS patients with COLQ mutations, as 98.7% of patients (74/75) treated with β-adrenergic agonists showed positive effects. In addition, AChEIs should be avoided in CMS patients with COLQ mutations, as 90.5% (105/116) of patients treated with AChEIs showed either no or negative effects. CONCLUSION (1) β-adrenergic agonist therapy is the first pharmacological strategy for treating CMS with COLQ mutations. (2) AChEIs should be avoided in patients with CMS with COLQ mutations.
Collapse
Affiliation(s)
- Shuai Shao
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan Province, China
- Xiangya School of Medicine, Central South University, Changsha, Hunan province, China
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan Province, China
| | - Guanzhong Shi
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan Province, China
- Xiangya School of Medicine, Central South University, Changsha, Hunan province, China
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan Province, China
| | - Fang-Fang Bi
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan Province, China
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan Province, China
| | - Kun Huang
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan Province, China
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan Province, China
| |
Collapse
|
9
|
Oh SJ, King PH, Schindler A. Life-Long Steroid Responsive Familial Myopathy With Docking Protein 7 Mutation. J Clin Neuromuscul Dis 2022; 24:80-84. [PMID: 36409338 DOI: 10.1097/cnd.0000000000000398] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Docking protein 7 (DOK7) congenital myasthenic syndrome (CMS) is characterized by limb-girdle weakness and lack of fluctuating fatigability simulating many familial myopathies. Albuterol is the first line of therapy in view of consistent improvement. Two brothers with progressive predominant biceps weakness for 1-3 years responded to prednisone treatment for 40-50 years. Various studies including muscle biopsy and many laboratory studies were unsuccessful for the definite diagnosis. Gene study, 40 years after the initial evaluation, confirmed the diagnosis of DOK7 CMS. These are the first reported cases of DOK7 CMS associated with a sustained benefit from corticosteroids.
Collapse
Affiliation(s)
- Shin J Oh
- Department of Neurology, University of Alabama at Birmingham, Birmingham, AL; and
| | - Peter H King
- Department of Neurology, University of Alabama at Birmingham, Birmingham, AL; and
| | - Alice Schindler
- Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD
| |
Collapse
|
10
|
Yang Y, Zhu J, Yao CL, Guo DA, He N, Mei QX, Feng GJ, Chen QH, Yang GY. Determination of six core components from Mahuang Xuanfei Zhike syrup in rat plasma and tissues by UPLC-MS/MS: Application to the pharmacokinetics and tissue distribution study. Biomed Chromatogr 2022; 36:e5496. [PMID: 36047933 DOI: 10.1002/bmc.5496] [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: 06/17/2022] [Revised: 08/25/2022] [Accepted: 08/28/2022] [Indexed: 11/07/2022]
Abstract
Mahuang Xuanfei Zhike (MXZ) syrup, a Chinese patent medicine, has been widely used in clinical treatment of cough. However, there is no reported method for quantitative analysis of the effective components of MXZ syrup in biological samples. In this study, the effective components of MXZ syrup were screened by network pharmacology and molecular docking technology, a sensitive and rapid method of ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was established to test the active components of MXZ syrup in rat plasma and tissue homogenates, including ephedrine, amygdalin, chlorogenic acid, harpagoside, forsythin and forsythoside A. Chromatographic separation was performed on a Waters Acquity UPLC HSS T3 column (2.1 × 50 mm, 1.8 μm) and the mass analysis was conducted in a Waters Xevo TQ mass spectrometer using multiple reaction positive and negative ion simultaneous monitoring mode (MRM). The results expounded that the linearity ranged from 0.3 ng/mL to 409.4 ng/mL, The extraction recoveries were all less than 8.33%, and the matrix effects were all less than 8.45, which met the requirements. The pharmacokinetic and tissue distribution results indicated that the main active components of MXZ syrup were absorbed quickly and eliminated slowly in vivo, and there may be a reabsorption process.
Collapse
Affiliation(s)
- Yang Yang
- Shenzhen Bao'an Authentic TCM Therapy Hospital
| | - Jing Zhu
- Shenzhen Bao'an Traditional Chinese Medicine Hospital, Guangzhou University of Chinese Medicine
| | - Chang-Liang Yao
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences
| | - De-An Guo
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences
| | - Na He
- Shenzhen Bao'an Traditional Chinese Medicine Hospital, Guangzhou University of Chinese Medicine
| | - Quan-Xi Mei
- Shenzhen Bao'an Authentic TCM Therapy Hospital
| | | | | | - Guang-Yi Yang
- Shenzhen Bao'an Traditional Chinese Medicine Hospital, Guangzhou University of Chinese Medicine
| |
Collapse
|
11
|
Menon D, Bril V. Pharmacotherapy of Generalized Myasthenia Gravis with Special Emphasis on Newer Biologicals. Drugs 2022; 82:865-887. [PMID: 35639288 PMCID: PMC9152838 DOI: 10.1007/s40265-022-01726-y] [Citation(s) in RCA: 42] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/25/2022] [Indexed: 11/20/2022]
Abstract
Myasthenia gravis (MG) is a chronic, fluctuating, antibody-mediated autoimmune disorder directed against the post-synaptic neuromuscular junctions of skeletal muscles, resulting in a wide spectrum of manifestations ranging from mild to potentially fatal. Given its unique natural course, designing an ideal trial design for MG has been wrought with difficulties and evidence in favour of several of the conventional agents is weak as per current standards. Despite this, acetylcholinesterases and corticosteroids have remained the cornerstones of treatment for several decades with intravenous immunoglobulins (IVIG) and therapeutic plasma exchange (PLEX) offering rapid treatment response, especially in crises. However, the treatment of MG entails long-term immunosuppression and conventional agents are viable options but take longer to act and have a number of class-specific adverse effects. Advances in immunology, translational medicine and drug development have seen the emergence of several newer biological agents which offer selective, target-specific immunotherapy with fewer side effects and rapid onset of action. Eculizumab is one of the newer agents that belong to the class of complement inhibitors and has been approved for the treatment of refractory general MG. Zilucoplan and ravulizumab are other agents in this group in clinical trials. Neisseria meningitis is a concern with all complement inhibitors, mandating vaccination. Neonatal Fc receptor (FcRn) inhibitors prevent immunoglobulin recycling and cause rapid reduction in antibody levels. Efgartigimod is an FcRn inhibitor recently approved for MG treatment, and rozanolixizumab, nipocalimab and batoclimab are other agents in clinical trial development. Although lacking high quality evidence from randomized clinical trials, clinical experience with the use of anti-CD20 rituximab has led to its use in refractory MG. Among novel targets, interleukin 6 (IL6) inhibitors such as satralizumab are promising and currently undergoing evaluation. Cutting-edge therapies include genetically modifying T cells to recognise chimeric antigen receptors (CAR) and chimeric autoantibody receptors (CAAR). These may offer sustained and long-term remissions, but are still in very early stages of evaluation. Hematopoietic stem cell transplantation (HSCT) allows immune resetting and offers sustained remission, but the induction regimens often involve serious systemic toxicity. While MG treatment is moving beyond conventional agents towards target-specific biologicals, lack of knowledge as to the initiation, maintenance, switching, tapering and long-term safety profile necessitates further research. These concerns and the high financial burden of novel agents may hamper widespread clinical use in the near future.
Collapse
Affiliation(s)
- Deepak Menon
- Department of Neurology, National Institute of Mental Health and Neurosciences, Bangalore, India
| | - Vera Bril
- Ellen and Martin Prosserman Centre for Neuromuscular Diseases, University Health Network, 5EC-309, Toronto General Hospital, University of Toronto, 200 Elizabeth St, Toronto, M5G 2C4, Canada.
| |
Collapse
|
12
|
Fatema K, Rahman M. Fast channel congenital myesthenic syndrome: Reporting two cases with mutation of CHRNE gene and short review. J Pediatr Neurosci 2022. [DOI: 10.4103/jpn.jpn_124_21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
|
13
|
Ramdas S, Beeson D. Congenital myasthenic syndromes: where do we go from here? Neuromuscul Disord 2021; 31:943-954. [PMID: 34736634 DOI: 10.1016/j.nmd.2021.07.400] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 07/22/2021] [Accepted: 07/27/2021] [Indexed: 11/27/2022]
Abstract
Congenital myasthenia syndromes are rare but often treatable conditions affecting neuromuscular transmission. They result from loss or impaired function of one of a number of proteins secondary to a genetic defect. An estimate of the prevalence in the UK gave 9.2 cases per million, however, this is likely an underestimate since the adoption of next generation sequencing for diagnosis away from specialist centres is enhancing the 'pick up' rate. Next generation sequencing has helped identify a series of novel genes that harbour mutations causative for congenital myasthenic syndrome that include not only genes that encode proteins specifically expressed at the neuromuscular junction but also those that are ubiquitously expressed. The list of genes harbouring disease-causing mutations for congenital myasthenic syndrome continues to expand and is now over 30, but with many of the newly identified genes it is increasingly being recognised that abnormal neuromuscular transmission is only one component of a multifaceted phenotype in which muscle, the central nervous system, and other organs may also be affected. Treatment can be tailored to the underlying molecular mechanism for impaired neuromuscular transmission but treating the more complex multifaceted disorders and will require development of new therapies.
Collapse
Affiliation(s)
- Sithara Ramdas
- MDUK Neuromuscular centre, Children's Hospital, John Radcliffe Hospital, Oxford, OX3 9DU, UK
| | - David Beeson
- Neurosciences Group, Weatherall Institute of Molecular Medicine, The John Radcliffe, Oxford OX3 9DS, UK.
| |
Collapse
|
14
|
Akkol EK, Karatoprak GŞ, Carpar E, Hussain Y, Khan H, Aschner M. Effects of Natural Products on Neuromuscular Junction. Curr Neuropharmacol 2021; 20:594-610. [PMID: 34561984 DOI: 10.2174/1570159x19666210924092627] [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: 01/11/2021] [Revised: 05/05/2021] [Accepted: 06/01/2021] [Indexed: 11/22/2022] Open
Abstract
Neuromuscular junction (NMJ) disorders result from damage, malfunction or absence of one or more key proteins involved in neuromuscular transmission, comprising a wide range of disorders. The most common pathology is antibody-mediated or downregulation of ion channels or receptors, resulting in Lambert-Eaton myasthenic syndrome, myasthenia gravis, and acquired neuromyotonia (Isaac's syndrome), and rarely congenital myasthenic syndromes caused by mutations in NMJ proteins. A wide range of symptomatic treatments, immunomodulating therapies, or immunosuppressive drugs have been used to treat NMJ diseases. Future research must be directed at better understanding of the pathogenesis of these diseases, and developing novel disease-specific treatments. Numerous secondary metabolites, especially alkaloids isolated from plants have been used to treat NMJ diseases in traditional and clinical practices. An ethnopharmacological approach has provided leads for identifying new treatment for NMJ diseases. In this review, we performed a literature survey in Pubmed, Science Direct, and Google Scholar to gather information on drug discovery from plant sources for NMJ disease treatments. To date, most research has focused on the effect of herbal remedies on cholinesterase inhibitory and antioxidant activities. This review provides leads for identifying potential new drugs from plant sources for the treatment of NMJ diseases.
Collapse
Affiliation(s)
- Esra Küpeli Akkol
- Department of Pharmacognosy, Faculty of Pharmacy, Gazi University, 06330, Ankara. Turkey
| | - Gökçe Şeker Karatoprak
- Department of Pharmacognosy, Faculty of Pharmacy, Erciyes University, 38039, Kayseri. Turkey
| | - Elif Carpar
- Department of Psychiatry, Private French La Paix Hospital, 34360, Istanbul. Turkey
| | - Yaseen Hussain
- College of Pharmaceutical Sciences, Soochow University, Suzhou, Jiangsu, China
| | - Haroon Khan
- Department of Pharmacy, Abdul Wali Khan University Mardan, 23200, Mardan. Pakistan
| | - Michael Aschner
- Department of Molecular Pharmacology, Albert Einstein College of Medicine Forchheimer 209 1300 Morris Park Avenue, Bronx, NY 10461, United States
| |
Collapse
|
15
|
Webster RG, Vanhaesebrouck AE, Maxwell SE, Cossins JA, Liu W, Ueta R, Yamanashi Y, Beeson DMW. Effect of salbutamol on neuromuscular junction function and structure in a mouse model of DOK7 congenital myasthenia. Hum Mol Genet 2021; 29:2325-2336. [PMID: 32543656 PMCID: PMC7424765 DOI: 10.1093/hmg/ddaa116] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2020] [Revised: 06/07/2020] [Accepted: 06/08/2020] [Indexed: 12/28/2022] Open
Abstract
Congenital myasthenic syndromes (CMS) are characterized by fatigable muscle weakness resulting from impaired neuromuscular transmission. β2-adrenergic agonists are an effective treatment for DOK7-CMS. DOK7 is a component within the AGRN-LRP4-MUSK-DOK7 signalling pathway that is key for the formation and maintenance of the synaptic structure of the neuromuscular junction (NMJ). The precise mechanism of action of β2-adrenergic agonists at the NMJ is not fully understood. In this study, we investigated whether β2-adrenergic agonists improve both neurotransmission and structural integrity of the NMJ in a mouse model of DOK7-CMS. Ex-vivo electrophysiological techniques and microscopy of the NMJ were used to study the effect of salbutamol, a β2-adrenergic agonist, on synaptic structure and function. DOK7-CMS model mice displayed a severe phenotype with reduced weight gain and perinatal lethality. Salbutamol treatment improved weight gain and survival in DOK7 myasthenic mice. Model animals had fewer active NMJs, detectable by endplate recordings, compared with age-matched wild-type littermates. Salbutamol treatment increased the number of detectable NMJs during endplate recording. Correspondingly, model mice had fewer acetylcholine receptor-stained NMJs detected by fluorescent labelling, but following salbutamol treatment an increased number were detectable. The data demonstrate that salbutamol can prolong survival and increase NMJ number in a severe model of DOK7-CMS.
Collapse
Affiliation(s)
- Richard G Webster
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford OX3 9DS, UK
| | - An E Vanhaesebrouck
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford OX3 9DS, UK
| | - Susan E Maxwell
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford OX3 9DS, UK
| | - Judith A Cossins
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford OX3 9DS, UK
| | - Weiwei Liu
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford OX3 9DS, UK
| | - Ryo Ueta
- Division of Genetics, Department of Cancer Biology, Institute of Medical Science, The University of Tokyo, Tokyo 135-8550, Japan
| | - Yuji Yamanashi
- Division of Genetics, Department of Cancer Biology, Institute of Medical Science, The University of Tokyo, Tokyo 135-8550, Japan
| | - David M W Beeson
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford OX3 9DS, UK
| |
Collapse
|
16
|
Alsallum MS, Alshareef A, Abuzinadah AR, Bamaga AK, Dallol A. A novel DOK7 mutation causing congenital myasthenic syndrome with limb-girdle weakness: case series of three family members. Heliyon 2021; 7:e06869. [PMID: 34027146 PMCID: PMC8120944 DOI: 10.1016/j.heliyon.2021.e06869] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 11/05/2020] [Accepted: 04/16/2021] [Indexed: 11/12/2022] Open
Abstract
Congenital myasthenia syndrome (CMS) is a group of heterogeneous diseases affecting the neuromuscular endplate. CMS has a considerably different phenotypic presentations, with the onset time ranging from early infancy to late adulthood. Here, we report a case of a CMS due to a new DOK7 mutation in a 28-year-old man and two of his sisters, who have a pure limb-girdle weakness. DOK7 CMS has a varying presentation. Typically, the onset occurs in childhood with ptosis, bulbar symptoms, difficulty walking, weakness, and gait abnormality. This case sheds light on a novel DOK7 gene mutation with a unique presentation of CMS and provides insight into its unique phenotypic presentation.
Collapse
Affiliation(s)
- Mohammed S Alsallum
- Neurology Resident, King Abdulaziz University Hospital, P.O. Box: 80200, 21589, Jeddah, Saudi Arabia
| | - Aysha Alshareef
- King Abdulaziz University, Faculty of Medicine, King Abdulaziz University Hospital, Internal Medicine Department, Neurology Division, P.O. Box: 80200, 21589, Jeddah, Saudi Arabia.,Neuromuscular Unit, King Fahad Medical Research Center, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Ahmad R Abuzinadah
- King Abdulaziz University, Faculty of Medicine, King Abdulaziz University Hospital, Internal Medicine Department, Neurology Division, P.O. Box: 80200, 21589, Jeddah, Saudi Arabia.,Neuromuscular Unit, King Fahad Medical Research Center, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Ahmed K Bamaga
- Neuromuscular Unit, King Fahad Medical Research Center, King Abdulaziz University, Jeddah, Saudi Arabia.,King Abdulaziz University, Faculty of Medicine, King Abdulaziz University Hospital, Pediatric Department, Neurology Division, P.O. Box: 80200, 21589, Jeddah, Saudi Arabia
| | - Ashraf Dallol
- Center of Excellence in Genomic Medicine Research and Faculty of Applied Medical Sciences, King Abdulaziz University, P.O. Box: 80200, 21589, Saudi Arabia
| |
Collapse
|
17
|
Hotta H, Iimura K, Watanabe N, Shigemoto K. Maintenance of contractile force of the hind limb muscles by the somato-lumbar sympathetic reflexes. J Physiol Sci 2021; 71:15. [PMID: 34020583 PMCID: PMC10717212 DOI: 10.1186/s12576-021-00799-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Accepted: 04/29/2021] [Indexed: 11/10/2022]
Abstract
This study aimed to clarify whether the reflex excitation of muscle sympathetic nerves induced by contractions of the skeletal muscles modulates their contractility. In anesthetized rats, isometric tetanic contractions of the triceps surae muscles were induced by electrical stimulation of the intact tibial nerve before and after transection of the lumbar sympathetic trunk (LST), spinal cord, or dorsal roots. The amplitude of the tetanic force (TF) was reduced by approximately 10% at 20 min after transection of the LST, spinal cord, or dorsal roots. The recorded postganglionic sympathetic nerve activity from the lumbar gray ramus revealed that both spinal and supraspinal reflexes were induced in response to the contractions. Repetitive electrical stimulation of the cut peripheral end of the LST increased the TF amplitude. Our results indicated that the spinal and supraspinal somato-sympathetic nerve reflexes induced by contractions of the skeletal muscles contribute to the maintenance of their own contractile force.
Collapse
Affiliation(s)
- Harumi Hotta
- Department of Autonomic Neuroscience, Tokyo Metropolitan Institute of Gerontology, 35-2 Sakaecho, Itabashi-ku, Tokyo, 173-0015, Japan.
| | - Kaori Iimura
- Department of Autonomic Neuroscience, Tokyo Metropolitan Institute of Gerontology, 35-2 Sakaecho, Itabashi-ku, Tokyo, 173-0015, Japan
| | - Nobuhiro Watanabe
- Department of Autonomic Neuroscience, Tokyo Metropolitan Institute of Gerontology, 35-2 Sakaecho, Itabashi-ku, Tokyo, 173-0015, Japan
| | - Kazuhiro Shigemoto
- Department of Geriatric Medicine, Tokyo Metropolitan Institute of Gerontology, Tokyo, 173-0015, Japan
| |
Collapse
|
18
|
Straka T, Schröder C, Roos A, Kollipara L, Sickmann A, Williams MPI, Hafner M, Khan MM, Rudolf R. Regulatory Function of Sympathetic Innervation on the Endo/Lysosomal Trafficking of Acetylcholine Receptor. Front Physiol 2021; 12:626707. [PMID: 33776791 PMCID: PMC7991846 DOI: 10.3389/fphys.2021.626707] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Accepted: 02/08/2021] [Indexed: 01/02/2023] Open
Abstract
Recent studies have demonstrated that neuromuscular junctions are co-innervated by sympathetic neurons. This co-innervation has been shown to be crucial for neuromuscular junction morphology and functional maintenance. To improve our understanding of how sympathetic innervation affects nerve–muscle synapse homeostasis, we here used in vivo imaging, proteomic, biochemical, and microscopic approaches to compare normal and sympathectomized mouse hindlimb muscles. Live confocal microscopy revealed reduced fiber diameters, enhanced acetylcholine receptor turnover, and increased amounts of endo/lysosomal acetylcholine-receptor-bearing vesicles. Proteomics analysis of sympathectomized skeletal muscles showed that besides massive changes in mitochondrial, sarcomeric, and ribosomal proteins, the relative abundance of vesicular trafficking markers was affected by sympathectomy. Immunofluorescence and Western blot approaches corroborated these findings and, in addition, suggested local upregulation and enrichment of endo/lysosomal progression and autophagy markers, Rab 7 and p62, at the sarcomeric regions of muscle fibers and neuromuscular junctions. In summary, these data give novel insights into the relevance of sympathetic innervation for the homeostasis of muscle and neuromuscular junctions. They are consistent with an upregulation of endocytic and autophagic trafficking at the whole muscle level and at the neuromuscular junction.
Collapse
Affiliation(s)
- Tatjana Straka
- Institute of Molecular and Cell Biology, Mannheim University of Applied Sciences, Mannheim, Germany.,Institute of Toxicology and Genetics, Karlsruhe Institute of Technology, Karlsruhe, Germany.,Interdisciplinary Center for Neurosciences, Heidelberg University, Heidelberg, Germany
| | - Charlotte Schröder
- Leibniz-Institut für Analytische Wissenschaften-ISAS-e.V., Dortmund, Germany
| | - Andreas Roos
- Department of Neuropediatrics, University Hospital Essen, Essen, Germany.,Children's Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada
| | | | - Albert Sickmann
- Leibniz-Institut für Analytische Wissenschaften-ISAS-e.V., Dortmund, Germany.,Department of Chemistry, College of Physical Sciences, University of Aberdeen, Aberdeen, United Kingdom.,Medizinische Fakultät, Medizinische Proteom-Center (MPC), Ruhr-Universität Bochum, Bochum, Germany
| | | | - Mathias Hafner
- Institute of Molecular and Cell Biology, Mannheim University of Applied Sciences, Mannheim, Germany
| | - Muzamil Majid Khan
- Institute of Molecular and Cell Biology, Mannheim University of Applied Sciences, Mannheim, Germany.,Institute of Toxicology and Genetics, Karlsruhe Institute of Technology, Karlsruhe, Germany.,Interdisciplinary Center for Neurosciences, Heidelberg University, Heidelberg, Germany
| | - Rüdiger Rudolf
- Institute of Molecular and Cell Biology, Mannheim University of Applied Sciences, Mannheim, Germany.,Institute of Toxicology and Genetics, Karlsruhe Institute of Technology, Karlsruhe, Germany.,Interdisciplinary Center for Neurosciences, Heidelberg University, Heidelberg, Germany
| |
Collapse
|
19
|
Rodríguez Cruz PM, Cossins J, Beeson D, Vincent A. The Neuromuscular Junction in Health and Disease: Molecular Mechanisms Governing Synaptic Formation and Homeostasis. Front Mol Neurosci 2020; 13:610964. [PMID: 33343299 PMCID: PMC7744297 DOI: 10.3389/fnmol.2020.610964] [Citation(s) in RCA: 87] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Accepted: 10/30/2020] [Indexed: 12/28/2022] Open
Abstract
The neuromuscular junction (NMJ) is a highly specialized synapse between a motor neuron nerve terminal and its muscle fiber that are responsible for converting electrical impulses generated by the motor neuron into electrical activity in the muscle fibers. On arrival of the motor nerve action potential, calcium enters the presynaptic terminal, which leads to the release of the neurotransmitter acetylcholine (ACh). ACh crosses the synaptic gap and binds to ACh receptors (AChRs) tightly clustered on the surface of the muscle fiber; this leads to the endplate potential which initiates the muscle action potential that results in muscle contraction. This is a simplified version of the events in neuromuscular transmission that take place within milliseconds, and are dependent on a tiny but highly structured NMJ. Much of this review is devoted to describing in more detail the development, maturation, maintenance and regeneration of the NMJ, but first we describe briefly the most important molecules involved and the conditions that affect their numbers and function. Most important clinically worldwide, are myasthenia gravis (MG), the Lambert-Eaton myasthenic syndrome (LEMS) and congenital myasthenic syndromes (CMS), each of which causes specific molecular defects. In addition, we mention the neurotoxins from bacteria, snakes and many other species that interfere with neuromuscular transmission and cause potentially fatal diseases, but have also provided useful probes for investigating neuromuscular transmission. There are also changes in NMJ structure and function in motor neuron disease, spinal muscle atrophy and sarcopenia that are likely to be secondary but might provide treatment targets. The NMJ is one of the best studied and most disease-prone synapses in the nervous system and it is amenable to in vivo and ex vivo investigation and to systemic therapies that can help restore normal function.
Collapse
Affiliation(s)
- Pedro M. Rodríguez Cruz
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
- Neurosciences Group, Weatherall Institute of Molecular Medicine, University of Oxford, The John Radcliffe Hospital, Oxford, United Kingdom
| | - Judith Cossins
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
- Neurosciences Group, Weatherall Institute of Molecular Medicine, University of Oxford, The John Radcliffe Hospital, Oxford, United Kingdom
| | - David Beeson
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
- Neurosciences Group, Weatherall Institute of Molecular Medicine, University of Oxford, The John Radcliffe Hospital, Oxford, United Kingdom
| | - Angela Vincent
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
- Neurosciences Group, Weatherall Institute of Molecular Medicine, University of Oxford, The John Radcliffe Hospital, Oxford, United Kingdom
| |
Collapse
|
20
|
Di Bona A, Vita V, Costantini I, Zaglia T. Towards a clearer view of sympathetic innervation of cardiac and skeletal muscles. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2020; 154:80-93. [DOI: 10.1016/j.pbiomolbio.2019.07.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Revised: 07/02/2019] [Accepted: 07/11/2019] [Indexed: 02/07/2023]
|
21
|
Takamori M. Myasthenia Gravis: From the Viewpoint of Pathogenicity Focusing on Acetylcholine Receptor Clustering, Trans-Synaptic Homeostasis and Synaptic Stability. Front Mol Neurosci 2020; 13:86. [PMID: 32547365 PMCID: PMC7272578 DOI: 10.3389/fnmol.2020.00086] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Accepted: 04/28/2020] [Indexed: 12/18/2022] Open
Abstract
Myasthenia gravis (MG) is a disease of the postsynaptic neuromuscular junction (NMJ) where nicotinic acetylcholine (ACh) receptors (AChRs) are targeted by autoantibodies. Search for other pathogenic antigens has detected the antibodies against muscle-specific tyrosine kinase (MuSK) and low-density lipoprotein-related protein 4 (Lrp4), both causing pre- and post-synaptic impairments. Agrin is also suspected as a fourth pathogen. In a complex NMJ organization centering on MuSK: (1) the Wnt non-canonical pathway through the Wnt-Lrp4-MuSK cysteine-rich domain (CRD)-Dishevelled (Dvl, scaffold protein) signaling acts to form AChR prepatterning with axonal guidance; (2) the neural agrin-Lrp4-MuSK (Ig1/2 domains) signaling acts to form rapsyn-anchored AChR clusters at the innervated stage of muscle; (3) adaptor protein Dok-7 acts on MuSK activation for AChR clustering from “inside” and also on cytoskeleton to stabilize AChR clusters by the downstream effector Sorbs1/2; (4) the trans-synaptic retrograde signaling contributes to the presynaptic organization via: (i) Wnt-MuSK CRD-Dvl-β catenin-Slit 2 pathway; (ii) Lrp4; and (iii) laminins. The presynaptic Ca2+ homeostasis conditioning ACh release is modified by autoreceptors such as M1-type muscarinic AChR and A2A adenosine receptors. The post-synaptic structure is stabilized by: (i) laminin-network including the muscle-derived agrin; (ii) the extracellular matrix proteins (including collagen Q/perlecan and biglycan which link to MuSK Ig1 domain and CRD); and (iii) the dystrophin-associated glycoprotein complex. The study on MuSK ectodomains (Ig1/2 domains and CRD) recognized by antibodies suggested that the MuSK antibodies were pathologically heterogeneous due to their binding to multiple functional domains. Focussing one of the matrix proteins, biglycan which functions in the manner similar to collagen Q, our antibody assay showed the negative result in MG patients. However, the synaptic stability may be impaired by antibodies against MuSK ectodomains because of the linkage of biglycan with MuSK Ig1 domain and CRD. The pathogenic diversity of MG is discussed based on NMJ signaling molecules.
Collapse
|
22
|
Vanhaesebrouck AE, Webster R, Maxwell S, Rodriguez Cruz PM, Cossins J, Wickens J, Liu WW, Cetin H, Cheung J, Ramjattan H, Palace J, Beeson D. β2-Adrenergic receptor agonists ameliorate the adverse effect of long-term pyridostigmine on neuromuscular junction structure. Brain 2020; 142:3713-3727. [PMID: 31633155 PMCID: PMC6892641 DOI: 10.1093/brain/awz322] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 07/04/2019] [Accepted: 08/26/2019] [Indexed: 01/07/2023] Open
Abstract
Acetylcholine receptor deficiency is the most common form of the congenital myasthenic syndromes, a heterogeneous collection of genetic disorders of neuromuscular transmission characterized by fatiguable muscle weakness. Most patients with acetylcholine receptor deficiency respond well to acetylcholinesterase inhibitors; however, in some cases the efficacy of acetylcholinesterase inhibitors diminishes over time. Patients with acetylcholine receptor deficiency can also benefit from the addition of a β2-adrenergic receptor agonist to their medication. The working mechanism of β2-adrenergic agonists in myasthenic patients is not fully understood. Here, we report the long-term follow-up for the addition of β2-adrenergic agonists for a cohort of patients with acetylcholine receptor deficiency on anticholinesterase medication that demonstrates a sustained quantitative improvement. Coincidently we used a disease model to mirror the treatment of acetylcholine receptor deficiency, and demonstrate improved muscle fatigue, improved neuromuscular transmission and improved synaptic structure resulting from the addition of the β2-adrenergic agonist salbutamol to the anticholinesterase medication pyridostigmine. Following an initial improvement in muscle fatiguability, a gradual decline in the effect of pyridostigmine was observed in mice treated with pyridostigmine alone (P < 0.001). Combination therapy with pyridostigmine and salbutamol counteracted this decline (P < 0.001). Studies of compound muscle action potential decrement at high nerve stimulation frequencies (P < 0.05) and miniature end-plate potential amplitude analysis (P < 0.01) showed an improvement in mice following combination therapy, compared to pyridostigmine monotherapy. Pyridostigmine alone reduced postsynaptic areas (P < 0.001) and postsynaptic folding (P < 0.01). Combination therapy increased postsynaptic area (P < 0.001) and promoted the formation of postsynaptic junctional folds (P < 0.001), in particular in fast-twitch muscles. In conclusion, we demonstrate for the first time how the improvement seen in patients from adding salbutamol to their medication can be explained in an experimental model of acetylcholine receptor deficiency, the most common form of congenital myasthenic syndrome. Salbutamol enhances neuromuscular junction synaptic structure by counteracting the detrimental effects of long-term acetylcholinesterase inhibitors on the postsynaptic neuromuscular junction. The results have implications for both autoimmune and genetic myasthenias where anticholinesterase medication is a standard treatment.
Collapse
Affiliation(s)
- An E Vanhaesebrouck
- Neurosciences Group, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, OX3 9DS, UK
| | - Richard Webster
- Neurosciences Group, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, OX3 9DS, UK
| | - Susan Maxwell
- Neurosciences Group, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, OX3 9DS, UK
| | - Pedro M Rodriguez Cruz
- Neurosciences Group, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, OX3 9DS, UK.,Department of Clinical Neurology, John Radcliffe Hospital, University of Oxford, Oxford, OX3 9DU, UK
| | - Judith Cossins
- Neurosciences Group, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, OX3 9DS, UK
| | - James Wickens
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Oxford, OX1 3TA, UK
| | - Wei-Wei Liu
- Neurosciences Group, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, OX3 9DS, UK
| | - Hakan Cetin
- Neurosciences Group, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, OX3 9DS, UK
| | - Jonathan Cheung
- Neurosciences Group, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, OX3 9DS, UK
| | - Hayley Ramjattan
- Paediatric Neurology, John Radcliffe Hospital, University of Oxford, Oxford, OX3 9DU, UK
| | - Jacqueline Palace
- Department of Clinical Neurology, John Radcliffe Hospital, University of Oxford, Oxford, OX3 9DU, UK
| | - David Beeson
- Neurosciences Group, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, OX3 9DS, UK
| |
Collapse
|
23
|
Tannemaat MR, Verschuuren JJ. Emerging therapies for autoimmune myasthenia gravis: Towards treatment without corticosteroids. Neuromuscul Disord 2020; 30:111-119. [DOI: 10.1016/j.nmd.2019.12.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 12/09/2019] [Accepted: 12/11/2019] [Indexed: 12/22/2022]
|
24
|
Rodríguez Cruz PM, Cossins J, Cheung J, Maxwell S, Jayawant S, Herbst R, Waithe D, Kornev AP, Palace J, Beeson D. Congenital myasthenic syndrome due to mutations in MUSK suggests that the level of MuSK phosphorylation is crucial for governing synaptic structure. Hum Mutat 2019; 41:619-631. [PMID: 31765060 PMCID: PMC7028094 DOI: 10.1002/humu.23949] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Revised: 09/08/2019] [Accepted: 11/05/2019] [Indexed: 11/18/2022]
Abstract
MUSK encodes the muscle‐specific receptor tyrosine kinase (MuSK), a key component of the agrin‐LRP4‐MuSK‐DOK7 signaling pathway, which is essential for the formation and maintenance of highly specialized synapses between motor neurons and muscle fibers. We report a patient with severe early‐onset congenital myasthenic syndrome and two novel missense mutations in MUSK (p.C317R and p.A617V). Functional studies show that MUSK p.C317R, located at the frizzled‐like cysteine‐rich domain of MuSK, disrupts an integral part of MuSK architecture resulting in ablated MuSK phosphorylation and acetylcholine receptor (AChR) cluster formation. MUSK p.A617V, located at the kinase domain of MuSK, enhances MuSK phosphorylation resulting in anomalous AChR cluster formation. The identification and evidence for pathogenicity of MUSK mutations supported the initiation of treatment with β2‐adrenergic agonists with a dramatic improvement of muscle strength in the patient. This work suggests uncharacterized mechanisms in which control of the precise level of MuSK phosphorylation is crucial in governing synaptic structure.
Collapse
Affiliation(s)
- Pedro M Rodríguez Cruz
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK.,Neurosciences Group, The John Radcliffe Hospital, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
| | - Judith Cossins
- Neurosciences Group, The John Radcliffe Hospital, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
| | - Jonathan Cheung
- Neurosciences Group, The John Radcliffe Hospital, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
| | - Susan Maxwell
- Neurosciences Group, The John Radcliffe Hospital, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
| | - Sandeep Jayawant
- Department of Paediatric Neurology, Children's Hospital, John Radcliffe Hospital, Oxford, UK
| | - Ruth Herbst
- Center for Pathophysiology, Infectiology and Immunology, Medical Science Divisions, Medical University of Vienna, Vienna, Austria
| | - Dominic Waithe
- MRC Centre for Computational Biology and Wolfson Imaging Centre, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
| | - Alexandr P Kornev
- Department of Pharmacology, University of California at San Diego, La Jolla, California
| | - Jacqueline Palace
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - David Beeson
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK.,Neurosciences Group, The John Radcliffe Hospital, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
| |
Collapse
|
25
|
Barnett C, Tabasinejad R, Bril V. Current pharmacotherapeutic options for myasthenia gravis. Expert Opin Pharmacother 2019; 20:2295-2303. [PMID: 31670984 DOI: 10.1080/14656566.2019.1682548] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Introduction: Novel options for immune-based therapy in myasthenia gravis are improving the therapeutic outlook for patients. Multiple clinical trials on immunomodulation, complement inhibitors, and FcR inhibitors are providing evidence for novel immune-based therapies that promise to improve outcomes in myasthenia patients. These more focused immune treatments are reviewed in this paper.Areas covered: This paper outlines classical treatment for myasthenia gravis and then reviews recent clinical trial evidence for novel immune therapies, particularly complement inhibitors and FcR inhibitors. Further, as immune therapies expand in other areas of medicine, such as oncology, iatrogenic myasthenia is being observed as a complication of some novel treatments.Expert opinion: Exciting new options to help patients with myasthenia gravis are now available or in phase 3 trials based on promising phase 2 results. Manipulation of the immune system can also lead to iatrogenic MG. Although novel treatments can improve care for myasthenia gravis patients, future developments that prevent the production of specific abnormal auto-antibodies are desirable.
Collapse
Affiliation(s)
- Carolina Barnett
- Department of Medicine (Neurology), University Health Network, University of Toronto - Neurology, Toronto, Ontario, Canada
| | - Raha Tabasinejad
- Department of Medicine (Neurology), University Health Network, University of Toronto - Neurology, Toronto, Ontario, Canada
| | - Vera Bril
- Department of Medicine (Neurology), University Health Network, University of Toronto - Neurology, Toronto, Ontario, Canada
| |
Collapse
|
26
|
Nicolau S, Kao JC, Liewluck T. Trouble at the junction: When myopathy and myasthenia overlap. Muscle Nerve 2019; 60:648-657. [PMID: 31449669 DOI: 10.1002/mus.26676] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Revised: 08/18/2019] [Accepted: 08/20/2019] [Indexed: 12/22/2022]
Abstract
Although myopathies and neuromuscular junction disorders are typically distinct, their coexistence has been reported in several inherited and acquired conditions. Affected individuals have variable clinical phenotypes but typically display both a decrement on repetitive nerve stimulation and myopathic findings on muscle biopsy. Inherited causes include myopathies related to mutations in BIN1, DES, DNM2, GMPPB, MTM1, or PLEC and congenital myasthenic syndromes due to mutations in ALG2, ALG14, COL13A1, DOK7, DPAGT1, or GFPT1. Additionally, a decrement due to muscle fiber inexcitability is observed in certain myotonic disorders. The identification of a defect of neuromuscular transmission in an inherited myopathy may assist in establishing a molecular diagnosis and in selecting patients who would benefit from pharmacological correction of this defect. Acquired cases meanwhile stem from the co-occurrence of myasthenia gravis or Lambert-Eaton myasthenic syndrome with an immune-mediated myopathy, which may be due to paraneoplastic disorders or exposure to immune checkpoint inhibitors.
Collapse
Affiliation(s)
- Stefan Nicolau
- Department of Neurology, Mayo Clinic, Rochester, Minnesota
| | - Justin C Kao
- Department of Neurology, Auckland City Hospital, Auckland, New Zealand
| | | |
Collapse
|
27
|
Bryen SJ, Joshi H, Evesson FJ, Girard C, Ghaoui R, Waddell LB, Testa AC, Cummings B, Arbuckle S, Graf N, Webster R, MacArthur DG, Laing NG, Davis MR, Lührmann R, Cooper ST. Pathogenic Abnormal Splicing Due to Intronic Deletions that Induce Biophysical Space Constraint for Spliceosome Assembly. Am J Hum Genet 2019; 105:573-587. [PMID: 31447096 DOI: 10.1016/j.ajhg.2019.07.013] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Accepted: 07/22/2019] [Indexed: 10/26/2022] Open
Abstract
A precise genetic diagnosis is the single most important step for families with genetic disorders to enable personalized and preventative medicine. In addition to genetic variants in coding regions (exons) that can change a protein sequence, abnormal pre-mRNA splicing can be devastating for the encoded protein, inducing a frameshift or in-frame deletion/insertion of multiple residues. Non-coding variants that disrupt splicing are extremely challenging to identify. Stemming from an initial clinical discovery in two index Australian families, we define 25 families with genetic disorders caused by a class of pathogenic non-coding splice variant due to intronic deletions. These pathogenic intronic deletions spare all consensus splice motifs, though they critically shorten the minimal distance between the 5' splice-site (5'SS) and branchpoint. The mechanistic basis for abnormal splicing is due to biophysical constraint precluding U1/U2 spliceosome assembly, which stalls in A-complexes (that bridge the 5'SS and branchpoint). Substitution of deleted nucleotides with non-specific sequences restores spliceosome assembly and normal splicing, arguing against loss of an intronic element as the primary causal basis. Incremental lengthening of 5'SS-branchpoint length in our index EMD case subject defines 45-47 nt as the critical elongation enabling (inefficient) spliceosome assembly for EMD intron 5. The 5'SS-branchpoint space constraint mechanism, not currently factored by genomic informatics pipelines, is relevant to diagnosis and precision medicine across the breadth of Mendelian disorders and cancer genomics.
Collapse
|
28
|
Abstract
INTRODUCTION Mutations in the Dok-7 gene (DOK7) underlie a congenital myasthenic syndrome (CMS) with a characteristic limb-girdle (LG) pattern of muscle weakness. Multiple clinical findings and a wide clinical heterogeneity have been identified in this form of CMS. METHODS We describe here 2 unrelated adult patients who presented with a LG CMS, caused by 2 compound heterozygous pathogenic sequence variants in DOK7: c.1124_1127dupTGCC (P.Ala378Serfs*30) and c.480C> A (p.Tyr160*). RESULTS Although both patients presented with severe proximal weakness consistent with LG myasthenia, one of the patients presented with additional distal muscle involvement in the lower extremities. By contrast, the other patient had severe bulbar and respiratory deficit requiring gastric tube feeding and mechanical ventilatory support for most parts of the day. DISCUSSION These 2 cases illustrate the lack of phenotype-genotype correlation and the absence of geographic, genetic, and ethnic association in cases of LG CMS caused by DOK7 mutations.
Collapse
|
29
|
Barnett C, Herbelin L, Dimachkie MM, Barohn RJ. Measuring Clinical Treatment Response in Myasthenia Gravis. Neurol Clin 2019; 36:339-353. [PMID: 29655453 DOI: 10.1016/j.ncl.2018.01.006] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
In this article we provide an overview of health-related outcome measurement-to better understand what different outcomes used in myasthenia actually measure-and to provide some guidance when choosing measures based on the clinical context and question. In myasthenia, the most commonly used outcome measures are aimed at assessing the signs and symptoms. In this review, we provide a summary of the most commonly used outcome measures. We discuss instruments that gauge disease overall health impact, such as on disability and quality of life. Finally, we discuss other relevant outcomes such as steroid-sparing effects and the role of surrogate markers.
Collapse
Affiliation(s)
- Carolina Barnett
- Neurology (Medicine), University of Toronto, University Health Network, Toronto, Ontario, Canada.
| | - Laura Herbelin
- Department of Neurology, University of Kansas Medical Center, 3901 Rainbow Boulevard, Kansas City, KS 66160, USA
| | - Mazen M Dimachkie
- Department of Neurology, University of Kansas Medical Center, 3901 Rainbow Boulevard, Kansas City, KS 66160, USA
| | - Richard J Barohn
- Department of Neurology, University of Kansas Medical Center, 3901 Rainbow Boulevard, Kansas City, KS 66160, USA
| |
Collapse
|
30
|
McMacken GM, Spendiff S, Whittaker RG, O’Connor E, Howarth RM, Boczonadi V, Horvath R, Slater CR, Lochmüller H. Salbutamol modifies the neuromuscular junction in a mouse model of ColQ myasthenic syndrome. Hum Mol Genet 2019; 28:2339-2351. [PMID: 31220253 PMCID: PMC6606850 DOI: 10.1093/hmg/ddz059] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2019] [Revised: 03/14/2019] [Accepted: 03/15/2019] [Indexed: 12/23/2022] Open
Abstract
The β-adrenergic agonists salbutamol and ephedrine have proven to be effective as therapies for human disorders of the neuromuscular junction, in particular many subsets of congenital myasthenic syndromes. However, the mechanisms underlying this clinical benefit are unknown and improved understanding of the effect of adrenergic signalling on the neuromuscular junction is essential to facilitate the development of more targeted therapies. Here, we investigated the effect of salbutamol treatment on the neuromuscular junction in the ColQ deficient mouse, a model of end-plate acetylcholinesterase deficiency. ColQ-/- mice received 7 weeks of daily salbutamol injection, and the effect on muscle strength and neuromuscular junction morphology was analysed. We show that salbutamol leads to a gradual improvement in muscle strength in ColQ-/- mice. In addition, the neuromuscular junctions of salbutamol treated mice showed significant improvements in several postsynaptic morphological defects, including increased synaptic area, acetylcholine receptor area and density, and extent of postjunctional folds. These changes occurred without alterations in skeletal muscle fibre size or type. These findings suggest that β-adrenergic agonists lead to functional benefit in the ColQ-/- mouse and to long-term structural changes at the neuromuscular junction. These effects are primarily at the postsynaptic membrane and may lead to enhanced neuromuscular transmission.
Collapse
Affiliation(s)
- Grace M McMacken
- John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine, Newcastle University, Newcastle Upon Tyne, UK
| | - Sally Spendiff
- John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine, Newcastle University, Newcastle Upon Tyne, UK
- Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, Canada
| | - Roger G Whittaker
- Institute of Neuroscience, Newcastle University, Newcastle Upon Tyne, UK
| | - Emily O’Connor
- John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine, Newcastle University, Newcastle Upon Tyne, UK
| | - Rachel M Howarth
- John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine, Newcastle University, Newcastle Upon Tyne, UK
| | - Veronika Boczonadi
- Institute of Neuroscience, Newcastle University, Newcastle Upon Tyne, UK
| | - Rita Horvath
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - Clarke R Slater
- Institute of Neuroscience, Newcastle University, Newcastle Upon Tyne, UK
| | - Hanns Lochmüller
- Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, Canada
- Department of Neuropediatrics and Muscle Disorders, Medical Center – University of Freiburg, Faculty of Medicine, Freiburg, Germany
- Centro Nacional de Análisis Genómico (CNAG-CRG), Center for Genomic Regulation, Barcelona Institute of Science and Technology (BIST), Barcelona, Catalonia, Spain
- Division of Neurology, Department of Medicine, The Ottawa Hospital, Ottawa, Canada
| |
Collapse
|
31
|
Nicole S, Azuma Y, Bauché S, Eymard B, Lochmüller H, Slater C. Congenital Myasthenic Syndromes or Inherited Disorders of Neuromuscular Transmission: Recent Discoveries and Open Questions. J Neuromuscul Dis 2019; 4:269-284. [PMID: 29125502 PMCID: PMC5701762 DOI: 10.3233/jnd-170257] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Congenital myasthenic syndromes (CMS) form a heterogeneous group of rare diseases characterized by fatigable muscle weakness. They are genetically-inherited and caused by defective synaptic transmission at the cholinergic neuromuscular junction (NMJ). The number of genes known to cause CMS when mutated is currently 30, and the relationship between fatigable muscle weakness and defective functions is quite well-understood for many of them. However, some of the most recent discoveries in individuals with CMS challenge our knowledge of the NMJ, where the basis of the pathology has mostly been investigated in animal models. Frontier forms between CMS and congenital myopathy, which have been genetically and clinically identified, underline the poorly understood interplay between the synaptic and extrasynaptic molecules in the neuromuscular system. In addition, precise electrophysiological and histopathological investigations of individuals with CMS suggest an important role of NMJ plasticity in the response to CMS pathogenesis. While efficient drug-based treatments are already available to improve neuromuscular transmission for most forms of CMS, others, as well as neurological and muscular comorbidities, remain resistant. Taken together, the available pathological data point to physiological issues which remain to be understood in order to achieve precision medicine with efficient therapeutics for all individuals suffering from CMS.
Collapse
Affiliation(s)
- Sophie Nicole
- Inserm U 1127, CNRS UMR 7225, Sorbonne Universités, UPMC Université Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle épinière, ICM, 75013 Paris, France
| | - Yoshiteru Azuma
- John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine, Newcastle University, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK
| | - Stéphanie Bauché
- Inserm U 1127, CNRS UMR 7225, Sorbonne Universités, UPMC Université Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle épinière, ICM, 75013 Paris, France
| | - Bruno Eymard
- Inserm U 1127, CNRS UMR 7225, Sorbonne Universités, UPMC Université Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle épinière, ICM, 75013 Paris, France.,AP-HP, Hôpital Pitié-Salpétrière, 75013 Paris, France
| | - Hanns Lochmüller
- John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine, Newcastle University, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK
| | - Clarke Slater
- Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK
| |
Collapse
|
32
|
Abstract
OBJECTIVES Congenital myasthenic syndromes (CMSs) are a genotypically and phenotypically heterogeneous group of neuromuscular disorders, which have in common an impaired neuromuscular transmission. Since the field of CMSs is steadily expanding, the present review aimed at summarizing and discussing current knowledge and recent advances concerning the etiology, clinical presentation, diagnosis, and treatment of CMSs. METHODS Systematic literature review. RESULTS Currently, mutations in 32 genes are made responsible for autosomal dominant or autosomal recessive CMSs. These mutations concern 8 presynaptic, 4 synaptic, 15 post-synaptic, and 5 glycosilation proteins. These proteins function as ion-channels, enzymes, or structural, signalling, sensor, or transporter proteins. The most common causative genes are CHAT, COLQ, RAPSN, CHRNE, DOK7, and GFPT1. Phenotypically, these mutations manifest as abnormal fatigability or permanent or fluctuating weakness of extra-ocular, facial, bulbar, axial, respiratory, or limb muscles, hypotonia, or developmental delay. Cognitive disability, dysmorphism, neuropathy, or epilepsy are rare. Low- or high-frequency repetitive nerve stimulation may show an abnormal increment or decrement, and SF-EMG an increased jitter or blockings. Most CMSs respond favourably to acetylcholine-esterase inhibitors, 3,4-diamino-pyridine, salbutamol, albuterol, ephedrine, fluoxetine, or atracurium. CONCLUSIONS CMSs are an increasingly recognised group of genetically transmitted defects, which usually respond favorably to drugs enhancing the neuromuscular transmission. CMSs need to be differentiated from neuromuscular disorders due to muscle or nerve dysfunction.
Collapse
Affiliation(s)
- Josef Finsterer
- Krankenanstalt Rudolfstiftung, Messerli Institute, Veterinary University of Vienna, Postfach 20, 1180, Vienna, Austria.
| |
Collapse
|
33
|
Italian recommendations for diagnosis and management of congenital myasthenic syndromes. Neurol Sci 2018; 40:457-468. [PMID: 30554356 DOI: 10.1007/s10072-018-3682-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Accepted: 12/10/2018] [Indexed: 12/11/2022]
Abstract
Congenital myasthenic syndromes (CMS) are genetic disorders due to mutations in genes encoding proteins involved in the neuromuscular junction structure and function. CMS usually present in young children, but perinatal and adult onset has been reported. Clinical presentation is highly heterogeneous, ranging from mild symptoms to severe manifestations, sometimes with life-threatening respiratory episodes, especially in the first decade of life. Although considered rare, CMS are probably underestimated due to diagnostic difficulties. Because of the several therapeutic opportunities, CMS should be always considered in the differential diagnosis of neuromuscular disorders. The Italian Network on CMS proposes here recommendations for proper CMS diagnosis and management, aiming to guide clinicians in their practical approach to CMS patients.
Collapse
|
34
|
Clausen L, Cossins J, Beeson D. Beta-2 Adrenergic Receptor Agonists Enhance AChR Clustering in C2C12 Myotubes: Implications for Therapy of Myasthenic Disorders. J Neuromuscul Dis 2018; 5:231-240. [PMID: 29865088 PMCID: PMC6004912 DOI: 10.3233/jnd-170293] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Background: Congenital myasthenic syndromes (CMS) are a group of inherited neuromuscular transmission disorders causing fatiguable muscle weakness. ADRB2 agonists have been observed to provide therapeutic benefit where destabilisation of NMJ structures is part of the underlying pathology, such as in DOK7, COLQ and MuSK CMS as well as in slow channel syndrome. However, very little is known about the molecular mechanisms underlying the effects of ADRB2 agonists in CMS. Objective: In vitro investigation into whether an ADRB2 agonist affects the AChR clustering pathway and has the potential to increase the number and stability of AChR clusters. Methods: Cultured C2C12 mouse myotubes overexpressing the common DOK7 frameshift mutation c.1124_1127dupTGCC were incubated with salbutamol sulphate and the effect on AChR cluster numbers were investigated. Moreover, agrin-induced AChR clusters in C2C12 WT cells were left to disperse after agrin-wash-off, and the effects of incubation with salbutamol sulphate on AChR cluster numbers were explored. Results: Salbutamol sulphate induced a significant increase in the number of AChR clusters formed on C2C12 cells overexpressing c.1124_1127dupTGCC. Furthermore, significantly more clusters remained in C2C12 WT myotubes incubated with salbutamol sulphate following agrin wash-off. Conclusions: The results suggest that ADRB2 agonists directly affect proteins located at the neuromuscular junction and exert a stabilising effect on AChR clusters.
Collapse
Affiliation(s)
- Lisa Clausen
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Headley Way, Oxford, UK
| | - Judith Cossins
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Headley Way, Oxford, UK
| | - David Beeson
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Headley Way, Oxford, UK
| |
Collapse
|
35
|
Abstract
PURPOSE OF REVIEW Summarize features of the currently recognized congenital myasthenic syndromes (CMS) with emphasis on novel findings identified in the past 6 years. RECENT FINDINGS Since the last review of the CMS in this journal in 2012, several novel CMS were identified. The identified disease proteins are SNAP25B, synaptotagmin 2, Munc13-1, synaptobrevin-1, GFPT1, DPAGT1, ALG2, ALG14, Agrin, GMPPB, LRP4, myosin 9A, collagen 13A1, the mitochondrial citrate carrier, PREPL, LAMA5, the vesicular ACh transporter, and the high-affinity presynaptic choline transporter. Exome sequencing has provided a powerful tool for identifying novel CMS. Identifying the disease genes is essential for determining optimal therapy. The landscape of the CMS is still unfolding.
Collapse
Affiliation(s)
- Andrew G Engel
- Department of Neurology, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA.
| |
Collapse
|
36
|
Rodríguez Cruz PM, Palace J, Beeson D. The Neuromuscular Junction and Wide Heterogeneity of Congenital Myasthenic Syndromes. Int J Mol Sci 2018; 19:ijms19061677. [PMID: 29874875 PMCID: PMC6032286 DOI: 10.3390/ijms19061677] [Citation(s) in RCA: 74] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Revised: 05/17/2018] [Accepted: 05/21/2018] [Indexed: 01/16/2023] Open
Abstract
Congenital myasthenic syndromes (CMS) are genetic disorders characterised by impaired neuromuscular transmission. This review provides an overview on CMS and highlights recent advances in the field, including novel CMS causative genes and improved therapeutic strategies. CMS due to mutations in SLC5A7 and SLC18A3, impairing the synthesis and recycling of acetylcholine, have recently been described. In addition, a novel group of CMS due to mutations in SNAP25B, SYT2, VAMP1, and UNC13A1 encoding molecules implicated in synaptic vesicles exocytosis has been characterised. The increasing number of presynaptic CMS exhibiting CNS manifestations along with neuromuscular weakness demonstrate that the myasthenia can be only a small part of a much more extensive disease phenotype. Moreover, the spectrum of glycosylation abnormalities has been increased with the report that GMPPB mutations can cause CMS, thus bridging myasthenic disorders with dystroglycanopathies. Finally, the discovery of COL13A1 mutations and laminin α5 deficiency has helped to draw attention to the role of extracellular matrix proteins for the formation and maintenance of muscle endplates. The benefit of β2-adrenergic agonists alone or combined with pyridostigmine or 3,4-Dyaminopiridine is increasingly being reported for different subtypes of CMS including AChR-deficiency and glycosylation abnormalities, thus expanding the therapeutic repertoire available.
Collapse
Affiliation(s)
- Pedro M Rodríguez Cruz
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK.
- Neurosciences Group, Weatherall Institute of Molecular Medicine, University of Oxford, The John Radcliffe Hospital, Oxford OX3 9DS, UK.
| | - Jacqueline Palace
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK.
| | - David Beeson
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK.
- Neurosciences Group, Weatherall Institute of Molecular Medicine, University of Oxford, The John Radcliffe Hospital, Oxford OX3 9DS, UK.
| |
Collapse
|
37
|
Dowling JJ, D. Gonorazky H, Cohn RD, Campbell C. Treating pediatric neuromuscular disorders: The future is now. Am J Med Genet A 2018; 176:804-841. [PMID: 28889642 PMCID: PMC5900978 DOI: 10.1002/ajmg.a.38418] [Citation(s) in RCA: 74] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Accepted: 07/31/2017] [Indexed: 12/12/2022]
Abstract
Pediatric neuromuscular diseases encompass all disorders with onset in childhood and where the primary area of pathology is in the peripheral nervous system. These conditions are largely genetic in etiology, and only those with a genetic underpinning will be presented in this review. This includes disorders of the anterior horn cell (e.g., spinal muscular atrophy), peripheral nerve (e.g., Charcot-Marie-Tooth disease), the neuromuscular junction (e.g., congenital myasthenic syndrome), and the muscle (myopathies and muscular dystrophies). Historically, pediatric neuromuscular disorders have uniformly been considered to be without treatment possibilities and to have dire prognoses. This perception has gradually changed, starting in part with the discovery and widespread application of corticosteroids for Duchenne muscular dystrophy. At present, several exciting therapeutic avenues are under investigation for a range of conditions, offering the potential for significant improvements in patient morbidities and mortality and, in some cases, curative intervention. In this review, we will present the current state of treatment for the most common pediatric neuromuscular conditions, and detail the treatment strategies with the greatest potential for helping with these devastating diseases.
Collapse
Affiliation(s)
- James J. Dowling
- Division of NeurologyHospital for Sick ChildrenTorontoOntarioCanada
- Program for Genetics and Genome BiologyHospital for Sick ChildrenTorontoOntarioCanada
- Departments of Paediatrics and Molecular GeneticsUniversity of TorontoTorontoOntarioCanada
| | | | - Ronald D. Cohn
- Program for Genetics and Genome BiologyHospital for Sick ChildrenTorontoOntarioCanada
- Departments of Paediatrics and Molecular GeneticsUniversity of TorontoTorontoOntarioCanada
| | - Craig Campbell
- Department of PediatricsClinical Neurological SciencesEpidemiologyWestern UniversityLondonOntarioCanada
| |
Collapse
|
38
|
Santos M, Cruz S, Peres J, Santos L, Tavares P, Basto JP, Salgado V, Valverde AH. DOK7 myasthenic syndrome with subacute adult onset during pregnancy and partial response to fluoxetine. Neuromuscul Disord 2018; 28:278-282. [DOI: 10.1016/j.nmd.2017.12.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Revised: 12/02/2017] [Accepted: 12/04/2017] [Indexed: 02/04/2023]
|
39
|
Lee M, Beeson D, Palace J. Therapeutic strategies for congenital myasthenic syndromes. Ann N Y Acad Sci 2018; 1412:129-136. [DOI: 10.1111/nyas.13538] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Revised: 09/28/2017] [Accepted: 10/02/2017] [Indexed: 12/20/2022]
Affiliation(s)
- Manon Lee
- Nuffield Department of Clinical Neurosciences; John Radcliffe Hospital; Oxford United Kingdom
| | - David Beeson
- The Weatherall Institute of Molecular Medicine, John Radcliffe Hospital; University of Oxford; Oxford United Kingdom
| | - Jacqueline Palace
- Nuffield Department of Clinical Neurosciences; John Radcliffe Hospital; Oxford United Kingdom
| |
Collapse
|
40
|
Abstract
PURPOSE OF REVIEW Congenital myasthenic syndromes (CMS) are a group of heterogeneous inherited disorders caused by mutations in genes encoding proteins essential for the integrity of neuromuscular transmission. This review updates the reader on recent findings that have expanded the phenotypic spectrum and suggested improved treatment strategies. RECENT FINDINGS The use of next-generation sequencing is continuing to unearth new genes in which mutations can give rise to defective neuromuscular transmission. The defective transmission may be part of an overall more complex phenotype in which there may be muscle, central nervous system or other involvement. Notably, mutations in series of genes encoding presynaptic proteins are being identified. Further work on mutations found in the AGRN-MUSK acetylcholine receptor clustering pathway has helped characterize the role of LRP4 and broadened the phenotypic spectrum for AGRN mutations. Mutations in another extracellular matrix protein, collagen 13A1 and in GMPPB have also been found to cause a CMS. Finally, there are an increasing number of reports for the beneficial effects of treatment with β2-adrenergic receptor agonists. SUMMARY Recent studies of the CMS illustrate the increasing complexity of the genetics, pathophysiological mechanisms and the need to tailor therapy for the genetic disorders of the neuromuscular junction.
Collapse
|
41
|
Ohno K, Ohkawara B, Ito M. Agrin-LRP4-MuSK signaling as a therapeutic target for myasthenia gravis and other neuromuscular disorders. Expert Opin Ther Targets 2017; 21:949-958. [PMID: 28825343 DOI: 10.1080/14728222.2017.1369960] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
INTRODUCTION Signal transduction at the neuromuscular junction (NMJ) is compromised in a diverse array of diseases including myasthenia gravis, Lambert-Eaton myasthenic syndrome, Isaacs' syndrome, congenital myasthenic syndromes, Fukuyama-type congenital muscular dystrophy, amyotrophic lateral sclerosis, and sarcopenia. Except for sarcopenia, all are orphan diseases. In addition, the NMJ signal transduction is impaired by tetanus, botulinum, curare, α-bungarotoxin, conotoxins, organophosphate, sarin, VX, and soman to name a few. Areas covered: This review covers the agrin-LRP4-MuSK signaling pathway, which drives clustering of acetylcholine receptors (AChRs) and ensures efficient signal transduction at the NMJ. We also address diseases caused by autoantibodies against the NMJ molecules and by germline mutations in genes encoding the NMJ molecules. Expert opinion: Representative small compounds to treat the defective NMJ signal transduction are cholinesterase inhibitors, which exert their effects by increasing the amount of acetylcholine at the synaptic space. Another possible therapeutic strategy to enhance the NMJ signal transduction is to increase the number of AChRs, but no currently available drug has this functionality.
Collapse
Affiliation(s)
- Kinji Ohno
- a Division of Neurogenetics , Nagoya University Graduate School of Medicine , Nagoya , Japan
| | - Bisei Ohkawara
- a Division of Neurogenetics , Nagoya University Graduate School of Medicine , Nagoya , Japan
| | - Mikako Ito
- a Division of Neurogenetics , Nagoya University Graduate School of Medicine , Nagoya , Japan
| |
Collapse
|
42
|
Al-Muhaizea MA, Al-Mobarak SB. COLQ-mutant Congenital Myasthenic Syndrome with Microcephaly: A Unique Case with Literature Review. Transl Neurosci 2017; 8:65-69. [PMID: 28744372 PMCID: PMC5518714 DOI: 10.1515/tnsci-2017-0011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Accepted: 05/15/2017] [Indexed: 11/15/2022] Open
Abstract
Congenital Myasthenic Syndrome (CMS) is a group of inherited neuromuscular junction disorders caused by defects in several genes. Clinical features include delayed motor milestones, recurrent respiratory illnesses and variable fatigable weakness. The central nervous system involvement is typically not part of the CMS. We report here a Saudi girl with genetically proven Collagen Like Tail Subunit Of Asymmetric Acetylcholinesterase (COLQ) mutation type CMS who has global developmental delay, microcephaly and respiratory failure. We have reviewed the literature regarding COLQ-type CMS and to the best of our knowledge this is the first ever reported association of congenital myasthenia syndrome with microcephaly.
Collapse
|
43
|
Bevilacqua JA, Lara M, Díaz J, Campero M, Vázquez J, Maselli RA. Congenital Myasthenic Syndrome due to DOK7 mutations in a family from Chile. Eur J Transl Myol 2017; 27:6832. [PMID: 29118959 PMCID: PMC5658635 DOI: 10.4081/ejtm.2017.6832] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Revised: 08/16/2017] [Accepted: 08/16/2017] [Indexed: 01/15/2023] Open
Abstract
Congenital myasthenic syndromes (CMS) are neuromuscular transmission disorders caused by mutations in genes encoding neuromuscular junction proteins. A 61-year-old female and her older sister showed bilateral ptosis, facial and proximal limb weakness, and scoliosis since childhood. Another female sibling had milder signs, while other family members were asymptomatic. Facial nerve repetitive stimulation in the proband showed decrement of muscle responses. Single fiber EMG revealed increased jitter and blocking. Muscle biopsy showed type 2-fiber atrophy, without tubular aggregates. Mutational analysis in the three affected siblings revealed two compound heterozygous mutations in DOK7: c.1457delC, that predicts p.Pro486Argfs*13 and truncates the protein C-terminal domain, and c.473G>A, that predicts p.Arg158Gln and disruption of the dok7-MuSK interaction in the phosphotyrosine binding (PTB) domain. Unaffected family members carried only one or neither mutation. Discussion Two of the affected sisters showed marked improvement with salbutamol treatment, which illustrates the benefits of a correct diagnosis and treatment of DOK7-CMS.
Collapse
Affiliation(s)
- Jorge A. Bevilacqua
- Full Professor. Unidad Neuromuscular, Departamento de Neurología y Neurocirugía, Hospital Clínico Universidad de Chile (HCUCH), Santos Dumont 999, 2º piso, Sector E. Independencia 8380456; Santiago, Chile. +56 2 27773882; +56 2 27378546 E-mails of co-authors Marian Lara: Jorge Díaz: Mario Campero: Jessica Vázquez: Ricardo A. Maselli:
| | - Marian Lara
- Department of Neurology, University of California Davis, Davis CA, USA
| | - Jorge Díaz
- Department of Radiology, University of Chile Clinical Hospital (HCUCH), Santiago, Chile
| | - Mario Campero
- Neuromuscular Unit, Department of Neurology and Neurosurgery, University of Chile Clinical Hospital (HCUCH), Santiago, Chile
| | - Jessica Vázquez
- Department of Neurology, University of California Davis, Davis CA, USA
| | | |
Collapse
|
44
|
Lipka AF, Vrinten C, van Zwet EW, Schimmel KJ, Cornel MC, Kuijpers MR, Hekster YA, Weinreich SS, Verschuuren JJ. Ephedrine treatment for autoimmune myasthenia gravis. Neuromuscul Disord 2017; 27:259-265. [DOI: 10.1016/j.nmd.2016.11.009] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Revised: 11/09/2016] [Accepted: 11/14/2016] [Indexed: 11/27/2022]
|
45
|
Ng F, Lee DC, Schrumpf LA, Mazurek ME, Lee Lo V, Gill SK, Maselli RA. Effect of 3,4-diaminopyridine at the murine neuromuscular junction. Muscle Nerve 2016; 55:223-231. [PMID: 27251582 DOI: 10.1002/mus.25208] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Revised: 05/19/2016] [Accepted: 05/31/2016] [Indexed: 11/09/2022]
Abstract
INTRODUCTION We investigated the effects of 3,4-diaminopyridine (3,4-DAP) and its acetylated metabolite, N-(4-amino-pyridin-3-yl) acetamide (3-Ac), at the mammalian neuromuscular junction. METHODS Quantal release of acetylcholine was studied in diaphragm muscles of mice, using in vitro intracellular microelectrode recordings. RESULTS Under conditions of low probability of release, 3,4-DAP produced a 1,000% increase in quantal release, but 3-Ac had no effect. Under conditions of normal probability of release, the effect of 3,4-DAP was modest and limited by concurrent depletion of synaptic vesicles, especially with high concentrations of 3,4-DAP and high frequencies of nerve stimulation. CONCLUSIONS These findings predict 3,4-DAP is most effective in conditions with low probability of quantal release, such as Lambert-Eaton myasthenic syndrome. A beneficial effect is also expected in disorders of neuromuscular transmission in which the effect of 3,4-DAP on quantal release is not limited by depletion of synaptic vesicles, such as postsynaptic congenital myasthenic syndromes. Muscle Nerve, 2016 Muscle Nerve 55: 223-231, 2017.
Collapse
Affiliation(s)
- Fiona Ng
- University of California, Davis School of Medicine Department of Neurology, University of California Davis, Davis, California, USA
| | - Diana C Lee
- University of California, Davis School of Medicine Department of Neurology, University of California Davis, Davis, California, USA
| | - Leah A Schrumpf
- University of California, Davis School of Medicine Department of Neurology, University of California Davis, Davis, California, USA
| | - Mary E Mazurek
- University of California, Davis School of Medicine Department of Neurology, University of California Davis, Davis, California, USA
| | - Victoria Lee Lo
- University of California, Davis School of Medicine Department of Neurology, University of California Davis, Davis, California, USA
| | - Sharleen K Gill
- University of California, Davis School of Medicine Department of Neurology, University of California Davis, Davis, California, USA
| | - Ricardo A Maselli
- University of California, Davis School of Medicine Department of Neurology, University of California Davis, Davis, California, USA
| |
Collapse
|
46
|
Buyan A, Kalli AC, Sansom MSP. Multiscale Simulations Suggest a Mechanism for the Association of the Dok7 PH Domain with PIP-Containing Membranes. PLoS Comput Biol 2016; 12:e1005028. [PMID: 27459095 PMCID: PMC4961371 DOI: 10.1371/journal.pcbi.1005028] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Accepted: 06/20/2016] [Indexed: 11/18/2022] Open
Abstract
Dok7 is a peripheral membrane protein that is associated with the MuSK receptor tyrosine kinase. Formation of the Dok7/MuSK/membrane complex is required for the activation of MuSK. This is a key step in the complex exchange of signals between neuron and muscle, which lead to neuromuscular junction formation, dysfunction of which is associated with congenital myasthenic syndromes. The Dok7 structure consists of a Pleckstrin Homology (PH) domain and a Phosphotyrosine Binding (PTB) domain. The mechanism of the Dok7 association with the membrane remains largely unknown. Using multi-scale molecular dynamics simulations we have explored the formation of the Dok7 PH/membrane complex. Our simulations indicate that the PH domain of Dok7 associates with membranes containing phosphatidylinositol phosphates (PIPs) via interactions of the β1/β2, β3/β4, and β5/β6 loops, which together form a positively charged surface on the PH domain and interact with the negatively charged headgroups of PIP molecules. The initial encounter of the Dok7 PH domain is followed by formation of additional interactions with the lipid bilayer, and especially with PIP molecules, which stabilizes the Dok7 PH/membrane complex. We have quantified the binding of the PH domain to the model bilayers by calculating a density landscape for protein/membrane interactions. Detailed analysis of the PH/PIP interactions reveal both a canonical and an atypical site to be occupied by the anionic lipid. PH domain binding leads to local clustering of PIP molecules in the bilayer. Association of the Dok7 PH domain with PIP lipids is therefore seen as a key step in localization of Dok7 to the membrane and formation of a complex with MuSK. Neuromuscular junction formation and maintenance is an essential biological process, the disruption of which leads to congenital myasthenic syndromes and premature death. Dok7 is a key member in formation, maintenance and signaling in neuromuscular junctions. Dok7 is a peripheral membrane protein that is necessary for full activation of the receptor tyrosine kinase MuSK, a receptor tyrosine kinase residing in the postsynaptic membrane. The structure of Dok7 consists of both a PH domain and a PTB domain. The interaction of Dok7 with cell membranes is not well understood. Here, we use molecular simulations to show that the Dok7 PH domain preferentially binds to PIP lipid molecules when associating with a membrane. Dok7 interacts with the bilayer in both a canonical binding mode and an alternative binding mode. Our simulations also demonstrate the presence of both a canonical and an atypical binding site for PIPs in agreement with recent crystallographic studies of the ASAP1 PH domain. Analysis of density landscapes for the interaction of the Dok7 PH domain with PIP-containing lipid bilayers is also able to identify both canonical and alternative binding modes. Our improved understanding of how Dok7 interacts with a membrane is key to examining Dok7/MuSK signaling.
Collapse
Affiliation(s)
- Amanda Buyan
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - Antreas C. Kalli
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - Mark S. P. Sansom
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
- * E-mail:
| |
Collapse
|
47
|
Sigoillot SM, Bourgeois F, Karmouch J, Molgó J, Dobbertin A, Chevalier C, Houlgatte R, Léger J, Legay C. Neuromuscular junction immaturity and muscle atrophy are hallmarks of the ColQ-deficient mouse, a model of congenital myasthenic syndrome with acetylcholinesterase deficiency. FASEB J 2016; 30:2382-99. [PMID: 26993635 DOI: 10.1096/fj.201500162] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Accepted: 02/26/2016] [Indexed: 12/13/2022]
Abstract
The collagen ColQ anchors acetylcholinesterase (AChE) in the synaptic cleft of the neuromuscular junction (NMJ). It also binds MuSK and perlecan/dystroglycan, 2 signaling platforms of the postsynaptic domain. Mutations in ColQ cause a congenital myasthenic syndrome (CMS) with AChE deficiency. Because the absence of AChE does not fully explain the complexity of the syndrome and there is no curative treatment for the disease, we explored additional potential targets of ColQ by conducting a large genetic screening of ColQ-deficient mice, a model for CMS with AChE deficiency, and analyzed their NMJ and muscle phenotypes. We demonstrated that ColQ controls the development and the maturation of the postsynaptic domain by regulating synaptic gene expression. Notably, ColQ deficiency leads to an up-regulation of the 5 subunits of the nicotinic acetylcholine receptor (AChR), leading to mixed mature and immature AChRs at the NMJ of adult mice. ColQ also regulates the expression of extracellular matrix (ECM) components. However, whereas the ECM mRNAs were down-regulated in vitro, compensation seemed to occur in vivo to maintain normal levels of these mRNAs. Finally, ColQ deficiency leads to a general atrophic phenotype and hypoplasia that affect fast muscles. This study points to new specific hallmarks for this CMS.-Sigoillot, S. M., Bourgeois, F., Karmouch, J., Molgó, J., Dobbertin, A., Chevalier, C., Houlgatte, R., Léger, J., Legay, C. Neuromuscular junction immaturity and muscle atrophy are hallmarks of the ColQ-deficient mouse, a model of congenital myasthenic syndrome with acetylcholinesterase deficiency.
Collapse
Affiliation(s)
- Séverine M Sigoillot
- Centre de Neurophysique, Physiologie et Pathologie, Centre National de la Recherche Scientifique (CNRS), Unité Mixte de Recherche (UMR) 8119, Université Paris Descartes, Sorbonne Paris Cité, Paris France
| | - Francine Bourgeois
- Centre de Neurophysique, Physiologie et Pathologie, Centre National de la Recherche Scientifique (CNRS), Unité Mixte de Recherche (UMR) 8119, Université Paris Descartes, Sorbonne Paris Cité, Paris France
| | - Jennifer Karmouch
- Centre de Neurophysique, Physiologie et Pathologie, Centre National de la Recherche Scientifique (CNRS), Unité Mixte de Recherche (UMR) 8119, Université Paris Descartes, Sorbonne Paris Cité, Paris France
| | - Jordi Molgó
- Commissariat à l'énergie Atomique et aux Energies Alternatives, Institut de Biologie et Technologies de Saclay, Service d'Ingénierie Moléculaire des Protéines, Gif sur Yvette, France; Institut des Neurosciences Paris-Saclay, UMR 9197, CNRS/Université Paris-Sud, Paris, France; and
| | - Alexandre Dobbertin
- Centre de Neurophysique, Physiologie et Pathologie, Centre National de la Recherche Scientifique (CNRS), Unité Mixte de Recherche (UMR) 8119, Université Paris Descartes, Sorbonne Paris Cité, Paris France
| | - Catherine Chevalier
- Institut de Recherche Thérapeutique de l'Université de Nantes, Plateforme Génomique Intégrative, Nantes, France
| | - Rémi Houlgatte
- Institut de Recherche Thérapeutique de l'Université de Nantes, Plateforme Génomique Intégrative, Nantes, France
| | - Jean Léger
- Institut de Recherche Thérapeutique de l'Université de Nantes, Plateforme Génomique Intégrative, Nantes, France
| | - Claire Legay
- Centre de Neurophysique, Physiologie et Pathologie, Centre National de la Recherche Scientifique (CNRS), Unité Mixte de Recherche (UMR) 8119, Université Paris Descartes, Sorbonne Paris Cité, Paris France;
| |
Collapse
|
48
|
Finlayson S, Morrow JM, Rodriguez Cruz PM, Sinclair CDJ, Fischmann A, Thornton JS, Knight S, Norbury R, White M, Al-Hajjar M, Carboni N, Jayawant S, Robb SA, Yousry TA, Beeson D, Palace J. Muscle magnetic resonance imaging in congenital myasthenic syndromes. Muscle Nerve 2016; 54:211-9. [PMID: 26789134 PMCID: PMC4982021 DOI: 10.1002/mus.25035] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Revised: 12/27/2015] [Accepted: 01/06/2016] [Indexed: 11/26/2022]
Abstract
Introduction In this study we investigated muscle magnetic resonance imaging in congenital myasthenic syndromes (CMS). Methods Twenty‐six patients with 9 CMS subtypes and 10 controls were imaged. T1‐weighted (T1w) and short‐tau inversion recovery (STIR) 3‐Tesla MRI images obtained at thigh and calf levels were scored for severity. Results Overall mean the T1w score was increased in GFPT1 and DPAGT1 CMS. T1w scans of the AChR‐deficiency, COLQ, and CHAT subjects were indistinguishable from controls. STIR images from CMS patients did not differ significantly from those of controls. Mean T1w score correlated with age in the CMS cohort. Conclusions MRI appearances ranged from normal to marked abnormality. T1w images seem to be especially abnormal in some CMS caused by mutations of proteins involved in the glycosylation pathway. A non‐selective pattern of fat infiltration or a normal‐appearing scan in the setting of significant clinical weakness should suggest CMS as a potential diagnosis. Muscle MRI could play a role in differentiating CMS subtypes. Muscle Nerve54: 211–219, 2016
Collapse
Affiliation(s)
- Sarah Finlayson
- Nuffield Department of Clinical Neurosciences, University of Oxford and Oxford Radcliffe Hospitals NHS Trust, Oxford, UK
| | - Jasper M Morrow
- MRC Centre for Neuromuscular Diseases, UCL Institute of Neurology, London, UK
| | - Pedro M Rodriguez Cruz
- Nuffield Department of Clinical Neurosciences, University of Oxford and Oxford Radcliffe Hospitals NHS Trust, Oxford, UK
| | | | - Arne Fischmann
- MRC Centre for Neuromuscular Diseases, UCL Institute of Neurology, London, UK
| | - John S Thornton
- MRC Centre for Neuromuscular Diseases, UCL Institute of Neurology, London, UK
| | - Steve Knight
- University of Oxford Centre for Clinical Magnetic Resonance Research, John Radcliffe Hospital, Oxford, UK
| | - Ray Norbury
- University of Oxford Centre for Clinical Magnetic Resonance Research, John Radcliffe Hospital, Oxford, UK
| | - Mel White
- Department of Paediatrics, University of Oxford and Children's Hospital, Oxford, UK
| | - Michal Al-Hajjar
- Nuffield Department of Clinical Neurosciences, University of Oxford and Oxford Radcliffe Hospitals NHS Trust, Oxford, UK
| | - Nicola Carboni
- Neurology Department, Hospital San Francesco of Nuoro, Sardinia, Italy
| | - Sandeep Jayawant
- Department of Paediatrics, University of Oxford and Children's Hospital, Oxford, UK
| | - Stephanie A Robb
- Dubowitz Neuromuscular Centre, Institute of Child Health and Great Ormond Street Hospital, London, UK
| | - Tarek A Yousry
- MRC Centre for Neuromuscular Diseases, UCL Institute of Neurology, London, UK
| | - David Beeson
- Neurosciences Group, Weatherall Institute of Molecular Medicine, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Jacqueline Palace
- Nuffield Department of Clinical Neurosciences, University of Oxford and Oxford Radcliffe Hospitals NHS Trust, Oxford, UK
| |
Collapse
|
49
|
Natera-de Benito D, Nascimento A, Abicht A, Ortez C, Jou C, Müller JS, Evangelista T, Töpf A, Thompson R, Jimenez-Mallebrera C, Colomer J, Lochmüller H. KLHL40-related nemaline myopathy with a sustained, positive response to treatment with acetylcholinesterase inhibitors. J Neurol 2016; 263:517-23. [DOI: 10.1007/s00415-015-8015-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Revised: 12/26/2015] [Accepted: 12/28/2015] [Indexed: 11/28/2022]
|
50
|
Rodríguez Cruz PM, Palace J, Ramjattan H, Jayawant S, Robb SA, Beeson D. Salbutamol and ephedrine in the treatment of severe AChR deficiency syndromes. Neurology 2015; 85:1043-7. [PMID: 26296515 DOI: 10.1212/wnl.0000000000001952] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVE To evaluate the response to salbutamol and ephedrine in the treatment of congenital myasthenic syndromes due to CHRNE mutations causing severe acetylcholine receptor (AChR)deficiency. METHODS A cohort study of 6 patients with severe AChR deficiency, symptomatic despite optimal therapy with anticholinesterase and 3,4-diaminopyridine, were analyzed for their response to the addition of salbutamol or ephedrine to their medication. Baseline quantitative myasthenia gravis (QMG) (severity) scores were worse than 15 of 39. Patients were assessed in clinic with QMG and mobility scores. Pretreatment and 6- to 8-month follow-up scores were evaluated. RESULTS All 6 patients tolerated treatment well and reported no side effects. There was a strong positive response to treatment over the 6- to 8-month assessment period with significant improvement in QMG (p = 0.027) and mobility scores. The analysis of subcomponents of the QMG score revealed marked improvement in upper (p = 0.028) and lower (p = 0.028) limb raise times. All patients reported enhanced activities of daily living at 6 to 8 months. CONCLUSIONS Oral salbutamol and ephedrine appear to be effective treatments in severe cases ofAChR deficiency on pyridostigmine. They are well tolerated and improvement in strength can be dramatic. Classification of evidence: This study provides Class IV evidence that salbutamol or ephedrine improves muscle strength in patients with congenital myasthenia from severe AChR deficiency.
Collapse
|