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Banerjee A, Datta Kanjilal S, Biswas T, Ghoshal A, Sarkar S. Congenital myasthenic syndrome: a tale of two siblings. Int J Neurosci 2024; 134:253-255. [PMID: 36018836 DOI: 10.1080/00207454.2022.2100774] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 06/29/2022] [Accepted: 06/30/2022] [Indexed: 10/15/2022]
Abstract
Congenital myasthenic syndromes are a group of rare neuromuscular junction disorders. Traditional anticholinesterase inhibitors may not help in congenital myasthenic syndromes and in some variants may actually cause deterioration of symptoms. In this report, we describe a rare case of congenital myasthenic syndrome with heterozygous mutations in CHRNE gene (c.128A > T; heterozygous; exon 11) and COLQ gene (c.1201T > A; heterozygous; exon 16), which did not show improvement on neostigmine test but responded to treatment with oral salbutamol.
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Affiliation(s)
- Ahitagni Banerjee
- Department of Pediatrics, Institute of Post Graduate Medical Education and Research, Kolkata, India
| | - Sumana Datta Kanjilal
- Department of Pediatrics, Institute of Post Graduate Medical Education and Research, Kolkata, India
| | - Tamoghna Biswas
- Department of Pediatrics, Institute of Post Graduate Medical Education and Research, Kolkata, India
| | - Arnab Ghoshal
- Department of Pediatrics, Institute of Post Graduate Medical Education and Research, Kolkata, India
| | - Sumit Sarkar
- Department of Pediatrics, Institute of Post Graduate Medical Education and Research, Kolkata, India
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Ohkawara B, Tomita H, Inoue T, Zhang S, Kanbara S, Koshimizu H, Miyasaka Y, Takeda JI, Nishiwaki H, Nakashima H, Ito M, Masuda A, Ishiguro N, Ogi T, Ohno T, Imagama S, Ohno K. Calcitriol ameliorates motor deficits and prolongs survival of Chrne-deficient mouse, a model for congenital myasthenic syndrome, by inducing Rspo2. Neurotherapeutics 2024; 21:e00318. [PMID: 38233267 DOI: 10.1016/j.neurot.2024.e00318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2023] [Revised: 01/02/2024] [Accepted: 01/03/2024] [Indexed: 01/19/2024] Open
Abstract
Signal transduction at the neuromuscular junction (NMJ) is compromised in a diverse array of diseases including congenital myasthenic syndromes (CMS). Germline mutations in CHRNE encoding the acetylcholine receptor (AChR) ε subunit are the most common cause of CMS. An active form of vitamin D, calcitriol, binds to vitamin D receptor (VDR) and regulates gene expressions. We found that calcitriol enhanced MuSK phosphorylation, AChR clustering, and myotube twitching in co-cultured C2C12 myotubes and NSC34 motor neurons. RNA-seq analysis of co-cultured cells showed that calcitriol increased the expressions of Rspo2, Rapsn, and Dusp6. ChIP-seq of VDR revealed that VDR binds to a region approximately 15 kbp upstream to Rspo2. Biallelic deletion of the VDR-binding site of Rspo2 by CRISPR/Cas9 in C2C12 myoblasts/myotubes nullified the calcitriol-mediated induction of Rspo2 expression and MuSK phosphorylation. We generated Chrne knockout (Chrne KO) mouse by CRISPR/Cas9. Intraperitoneal administration of calcitriol markedly increased the number of AChR clusters, as well as the area, the intensity, and the number of synaptophysin-positive synaptic vesicles, in Chrne KO mice. In addition, calcitriol ameliorated motor deficits and prolonged survival of Chrne KO mice. In the skeletal muscle, calcitriol increased the gene expressions of Rspo2, Rapsn, and Dusp6. We propose that calcitriol is a potential therapeutic agent for CMS and other diseases with defective neuromuscular signal transmission.
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Affiliation(s)
- Bisei Ohkawara
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya, Japan.
| | - Hiroyuki Tomita
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya, Japan; Department of Orthopedic Surgery, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Taro Inoue
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya, Japan; Department of Orthopedic Surgery, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Shaochuan Zhang
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Shunsuke Kanbara
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya, Japan; Department of Orthopedic Surgery, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Hiroyuki Koshimizu
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya, Japan; Department of Orthopedic Surgery, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Yuki Miyasaka
- Department of Genetics, Research Institute of Environmental Medicine (RIeM), Nagoya University, Nagoya, Japan
| | - Jun-Ichi Takeda
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Hiroshi Nishiwaki
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Hiroaki Nakashima
- Department of Orthopedic Surgery, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Mikako Ito
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Akio Masuda
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Naoki Ishiguro
- Department of Orthopedic Surgery, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Tomoo Ogi
- Department of Genetics, Research Institute of Environmental Medicine (RIeM), Nagoya University, Nagoya, Japan
| | - Tamio Ohno
- Division of Experimental Animals, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Shiro Imagama
- Department of Orthopedic Surgery, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Kinji Ohno
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya, Japan.
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Özsoy Ö, Cinleti T, Günay Ç, Sarıkaya Uzan G, Giray Bozkaya Ö, Çağlayan AO, Hız Kurul S, Yiş U. Genetic, serological and clinical evaluation of childhood myasthenia syndromes- single center subgroup analysis experience in Turkey. Acta Neurol Belg 2023; 123:2325-2335. [PMID: 37656362 DOI: 10.1007/s13760-023-02370-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Accepted: 08/21/2023] [Indexed: 09/02/2023]
Abstract
BACKGROUND Congenital myasthenic syndrome is a disease that occurs due to several types such as mutations in different pre-synaptic, synaptic, post-synaptic proteins and, glycosylation defects associated with congenital myopathy. Juvenile myasthenia gravis is an autoimmune condition usually caused by antibodies targeting the acetylcholine receptor. AIMS Our objective is to conduct an analysis on the subgroup traits exhibited by patients who have been diagnosed with congenital myasthenic syndrome and juvenile myasthenia gravis, with a focus on their long-term monitoring and management. METHODS This study was conducted on children diagnosed with myasthenia gravis, who were under the care of Dokuz Eylul University's Department of Pediatric Neurology for a period of ten years. RESULTS A total of 22 (12 congenital myasthenic syndrome, 10 juvenile myasthenia gravis) patients were identified. Defects in the acetylcholine receptor (6/12) were the most common type in the congenital myasthenic syndrome group. Basal-lamina-related defects (5/12) were the second most prevalent. One patient had a GFPT1 gene mutation (1/12). Patients with ocular myasthenia gravis (n = 6) exhibited milder symptoms. In the generalized myasthenia gravis group (n = 4), specifically in postpubertal girls, a more severe clinical progression was observed, leading to the implementation of more aggressive treatment strategies. CONCLUSION This study highlights that clinical recognition of congenital myasthenic syndrome and knowledge of related genes will aid the rapid diagnosis and treatment of these rare neuromuscular disorders. Findings in the juvenile myasthenia gravis group demonstrate the impact of pubertal development and the need for timely and appropriate active therapy, including thymectomy, to improve prognosis.
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Affiliation(s)
- Özlem Özsoy
- Department of Pediatric Neurology, Faculty of Medicine, Dokuz Eylül University, İzmir, Turkey.
| | - Tayfun Cinleti
- Department of Pediatric Genetics, Faculty of Medicine, Dokuz Eylül University, İzmir, Turkey
| | - Çağatay Günay
- Department of Pediatric Neurology, Faculty of Medicine, Dokuz Eylül University, İzmir, Turkey
| | - Gamze Sarıkaya Uzan
- Department of Pediatric Neurology, Faculty of Medicine, Dokuz Eylül University, İzmir, Turkey
| | - Özlem Giray Bozkaya
- Department of Pediatric Genetics, Faculty of Medicine, Dokuz Eylül University, İzmir, Turkey
| | - Ahmet Okay Çağlayan
- Department of Medical Genetics, Faculty of Medicine, Dokuz Eylül University, İzmir, Turkey
- Department of Molecular Medicine, Institute of Health Sciences, Dokuz Eylül University, İzmir, Turkey
| | - Semra Hız Kurul
- Department of Pediatric Neurology, Faculty of Medicine, Dokuz Eylül University, İzmir, Turkey
- İzmir Biomedicine and Genome Center, Dokuz Eylül University Health Campus, İzmir, Turkey
- İzmir International Biomedicine and Genome Institute, Dokuz Eylül University, İzmir, Turkey
| | - Uluç Yiş
- Department of Pediatric Neurology, Faculty of Medicine, Dokuz Eylül University, İzmir, Turkey
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Yildiz EP, Kilic MA, Yalcin EU, Kurekci F, Avci R, Hacıfazlıoğlu NE, Ceylaner S, Gezdirici A, Çalışkan M. Genetic and clinical evaluation of congenital myasthenic syndromes with long-term follow-up: experience of a tertiary center in Turkey. Acta Neurol Belg 2023; 123:1841-1847. [PMID: 36094697 DOI: 10.1007/s13760-022-02090-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Accepted: 09/01/2022] [Indexed: 11/30/2022]
Abstract
INTRODUCTION Congenital myasthenic syndromes (CMS) are a heterogeneous group of genetic disorders affecting the safety factor which required for neuromuscular transmission. Here we reported our experience in children with CMS. METHODS We retrospectively collected the data of 18 patients with CMS who were examined in our outpatient clinic between January 2021 and January 2022. The diagnosis of CMS was based on the presence of clinical symptoms such as abnormal fatigability and weakness, absence of autoantibodies against acetylcholine receptor and muscle-specific kinase, electromyographic evidence of neuromuscular junction defect, molecular genetic confirmation, and response to treatment. RESULTS The most common mutations were in the acetylcholine receptor (CHRNE) gene (8/18) and choline acetyltransferase (ChAT) (2/18) gene. Despite targeted gene sequencing and whole exome sequencing (WES) were underwent, we couldn't detect a genetic mutation in three out of patients. The most commonly determined initial finding was eyelid ptosis, followed by fatigable weakness, and respiratory insufficiency. Although the most commonly used drug was pyridostigmine, we have experienced that caution should be exercised as it may worsen some types of CMS. DISCUSSION We reported in detail the phenotypic features of very rare gene mutations associated with CMS and our experience in the treatment of this disease. Although CMS are rare genetic disorder, the prognosis can be very promising with appropriate treatment in most CMS subtypes.
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Affiliation(s)
- Edibe Pembegul Yildiz
- Department of Pediatric Neurology, Istanbul Medical Faculty, Istanbul, Turkey.
- Istanbul University Institute of Child Health, Istanbul, Turkey.
- Istanbul University Medical School. Millet Cd, 34000, Fatih-Istanbul, Turkey.
| | - Mehmet Akif Kilic
- Department of Pediatric Neurology, Istanbul Medical Faculty, Istanbul, Turkey
| | - Emek Uyur Yalcin
- Department of Pediatric Neurology, Zeynep Kamil Maternity and Children's Diseases Training and Research Hospital, University of Health Sciences, Istanbul, Turkey
| | - Fulya Kurekci
- Department of Pediatric Neurology, Istanbul Medical Faculty, Istanbul, Turkey
| | - Ridvan Avci
- Department of Pediatric Neurology, Istanbul Medical Faculty, Istanbul, Turkey
| | - Nilüfer Eldeş Hacıfazlıoğlu
- Department of Pediatric Neurology, Zeynep Kamil Maternity and Children's Diseases Training and Research Hospital, University of Health Sciences, Istanbul, Turkey
| | | | - Alper Gezdirici
- Department of Medical Genetics, Basaksehir Cam and Sakura City Hospital, Istanbul, Turkey
| | - Mine Çalışkan
- Department of Pediatric Neurology, Istanbul Medical Faculty, Istanbul, Turkey
- Istanbul University Institute of Child Health, Istanbul, Turkey
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Rizvi M, Truong TK, Zhou J, Batta M, Moran ES, Pappas J, Chu ML, Caluseriu O, Evrony GD, Leslie EM, Cordat E. Biochemical characterization of two novel mutations in the human high-affinity choline transporter 1 identified in a patient with congenital myasthenic syndrome. Hum Mol Genet 2023; 32:1552-1564. [PMID: 36611016 DOI: 10.1093/hmg/ddac309] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 12/21/2022] [Accepted: 12/22/2022] [Indexed: 01/09/2023] Open
Abstract
Congenital myasthenic syndrome (CMS) is a heterogeneous condition associated with 34 different genes, including SLC5A7, which encodes the high-affinity choline transporter 1 (CHT1). CHT1 is expressed in presynaptic neurons of the neuromuscular junction where it uses the inward sodium gradient to reuptake choline. Biallelic CHT1 mutations often lead to neonatal lethality, and less commonly to non-lethal motor weakness and developmental delays. Here, we report detailed biochemical characterization of two novel mutations in CHT1, p.I294T and p.D349N, which we identified in an 11-year-old patient with a history of neonatal respiratory distress, and subsequent hypotonia and global developmental delay. Heterologous expression of each CHT1 mutant in human embryonic kidney cells showed two different mechanisms of reduced protein function. The p.I294T CHT1 mutant transporter function was detectable, but its abundance and half-life were significantly reduced. In contrast, the p.D349N CHT1 mutant was abundantly expressed at the cell membrane, but transporter function was absent. The residual function of the p.I294T CHT1 mutant may explain the non-lethal form of CMS in this patient, and the divergent mechanisms of reduced CHT1 function that we identified may guide future functional studies of the CHT1 myasthenic syndrome. Based on these in vitro studies that provided a diagnosis, treatment with cholinesterase inhibitor together with physical and occupational therapy significantly improved the patient's strength and quality of life.
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Affiliation(s)
- Midhat Rizvi
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada
- Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada
| | - Tina K Truong
- Center for Human Genetics and Genomics, New York University Grossman School of Medicine, New York, NY, USA
| | - Janet Zhou
- Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada
- Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, Alberta, Canada
| | - Manav Batta
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada
- Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada
| | - Ellen S Moran
- Clinical Genetics, New York University Langone Orthopedic Hospital, New York, NY, USA
| | - John Pappas
- Division of Clinical Genetics, Department of Pediatrics, New York University Grossman School of Medicine, New York, NY, USA
| | - Mary Lynn Chu
- Department of Neurology, New York University School of Medicine, New York, NY, USA
| | - Oana Caluseriu
- Department of Medical Genetics, University of Alberta, Edmonton, Alberta, Canada
- Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada
| | - Gilad D Evrony
- Center for Human Genetics and Genomics, New York University Grossman School of Medicine, New York, NY, USA
- Department of Pediatrics, Department of Neuroscience and Physiology, New York University Grossman School of Medicine, New York, NY, USA
| | - Elaine M Leslie
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada
- Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada
- Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, Alberta, Canada
| | - Emmanuelle Cordat
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada
- Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada
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Mroczek M, Iyadurai S. Neuromuscular and Neuromuscular Junction Manifestations of the PURA-NDD: A Systematic Review of the Reported Symptoms and Potential Treatment Options. Int J Mol Sci 2023; 24:ijms24032260. [PMID: 36768582 PMCID: PMC9917016 DOI: 10.3390/ijms24032260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 01/14/2023] [Accepted: 01/20/2023] [Indexed: 01/26/2023] Open
Abstract
PURA-related neurodevelopmental disorders (PURA-NDDs) are a rare genetic disease caused by pathogenic autosomal dominant variants in the PURA gene or a deletion encompassing the PURA gene. PURA-NDD is clinically characterized by neurodevelopmental delay, learning disability, neonatal hypotonia, feeding difficulties, abnormal movements, and epilepsy. It is generally considered to be central nervous system disorders, with generalized weakness, associated hypotonia, cognitive and development deficits in early development, and seizures in late stages. Although it is classified predominantly as a central nervous syndrome disorder, some phenotypic features, such as myopathic facies, respiratory insufficiency of muscle origin, and myopathic features on muscle biopsy and electrodiagnostic evaluation, point to a peripheral (neuromuscular) source of weakness. Patients with PURA-NDD have been increasingly identified in exome-sequenced cohorts of patients with neuromuscular- and congenital myasthenic syndrome-like phenotypes. Recently, fluctuating weakness noted in a PURA-NDD patient, accompanied by repetitive nerve stimulation abnormalities, suggested the disease to be a channelopathy and, more specifically, a neuromuscular junction disorder. Treatment with pyridostigmine or salbutamol led to clinical improvement of neuromuscular function in two reported cases. The goal of this systematic retrospective review is to highlight the motor symptoms of PURA-NDD, to further describe the neuromuscular phenotype, and to emphasize the role of potential treatment opportunities of the neuromuscular phenotype in the setting of the potential role of PURA protein in the neuromuscular junction and the muscles.
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Affiliation(s)
- Magdalena Mroczek
- Center for Cardiovascular Genetics & Gene Diagnostics, Foundation for People with Rare Diseases, 8952 Schlieren, Switzerland
- Correspondence: (M.M.); (S.I.)
| | - Stanley Iyadurai
- Division of Neurology, Johns Hopkins All Children’s Hospital, 501 6th Ave S, St. Petersburg, FL 33701, USA
- Correspondence: (M.M.); (S.I.)
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Shao S, Shi G, Bi FF, Huang K. Pharmacological Treatments for Congenital Myasthenic Syndromes Caused by COLQ Mutations. Curr Neuropharmacol 2023; 21:1594-1605. [PMID: 36703579 PMCID: PMC10472815 DOI: 10.2174/1570159x21666230126145652] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2022] [Revised: 09/30/2022] [Accepted: 11/18/2022] [Indexed: 01/28/2023] Open
Abstract
BACKGROUND Congenital myasthenic syndromes (CMS) refer to a series of inherited disorders caused by defects in various proteins. Mutation in the collagen-like tail subunit of asymmetric acetylcholinesterase (COLQ) is the second-most common cause of CMS. However, data on pharmacological treatments are limited. OBJECTIVE In this study, we reviewed related reports to determine the most appropriate pharmacological strategy for CMS caused by COLQ mutations. A literature review and meta-analysis were also performed. PubMed, MEDLINE, Web of Science, and Cochrane Library databases were searched to identify studies published in English before July 22, 2022. RESULTS A total of 42 studies including 164 patients with CMS due to 72 different COLQ mutations were selected for evaluation. Most studies were case reports, and none were randomized clinical trials. Our meta-analysis revealed evidence that β-adrenergic agonists, including salbutamol and ephedrine, can be used as first-line pharmacological treatments for CMS patients with COLQ mutations, as 98.7% of patients (74/75) treated with β-adrenergic agonists showed positive effects. In addition, AChEIs should be avoided in CMS patients with COLQ mutations, as 90.5% (105/116) of patients treated with AChEIs showed either no or negative effects. CONCLUSION (1) β-adrenergic agonist therapy is the first pharmacological strategy for treating CMS with COLQ mutations. (2) AChEIs should be avoided in patients with CMS with COLQ mutations.
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Affiliation(s)
- Shuai Shao
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan Province, China
- Xiangya School of Medicine, Central South University, Changsha, Hunan province, China
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan Province, China
| | - Guanzhong Shi
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan Province, China
- Xiangya School of Medicine, Central South University, Changsha, Hunan province, China
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan Province, China
| | - Fang-Fang Bi
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan Province, China
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan Province, China
| | - Kun Huang
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan Province, China
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan Province, China
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O'Connell K, Rooney T, Alabaf S, Ramdas S, Beeson D, Palace J. Pregnancy outcomes in patients with congenital myasthenic syndromes. Muscle Nerve 2022; 66:345-348. [PMID: 35661384 DOI: 10.1002/mus.27653] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Revised: 05/22/2022] [Accepted: 05/28/2022] [Indexed: 11/08/2022]
Abstract
INTRODUCTION/AIMS The congenital myasthenic syndromes (CMS) are a heterogeneous group of inherited disorders that affect neuromuscular junction transmission. Data on pregnancy outcomes in women with CMS are limited due to their infrequency. In this study we explored pregnancy with CMS in a large cohort of women attending a national specialty clinic in England. METHODS All women with CMS who had a documented pregnancy were invited to complete a questionnaire assessing clinical status during pregnancy and postpartum, pregnancy outcomes, fetal outcomes, and medication use during pregnancy. RESULTS Among 16 women with CMS (acetylcholine receptor deficiency [CHRNE], slow channel syndrome [CHRNA1], DOK7, RAPSYN and glycosylation [DPAGT1 and GFPT1]), 27 pregnancies were recorded: 26 single pregnancies and 1 twin pregnancy. Symptom worsening was reported in 63% of pregnancies, but recovery to baseline function was seen in all but one patient. Miscarriage and cesarean section occurred in 31% and 33% of the women, respectively. Over half of the patients continued taking their medication during pregnancy, which included pyridostigmine (n = 10), 3,4-diaminopyridine (n = 9), ephedrine (n = 3), salbutamol (n = 3), and quinidine (n = 1). No fetal malformations were recorded. DISCUSSION Our results show that clinical worsening during pregnancy was common but rarely persistent. The majority of women with CMS can safely plan pregnancy, but close follow-up is required from their neurology and obstetric teams. Although we identified no safety concerns, continued medication use should be reviewed on a case-by-case basis.
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Affiliation(s)
- Karen O'Connell
- Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - Tatiana Rooney
- Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - Setareh Alabaf
- Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - Sithara Ramdas
- Department of Paediatric Neurology, John Radcliffe Hospital, Oxford, UK
| | - David Beeson
- Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, University of Oxford, Oxford, UK
- Neurosciences Group, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
| | - Jacqueline Palace
- Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, University of Oxford, Oxford, UK
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Affiliation(s)
- K Tayade
- From the Department of Neurology, Cardioneurosciences Centre, All India Institute of Medical Sciences, New Delhi, India
| | - M Salunkhe
- From the Department of Neurology, Cardioneurosciences Centre, All India Institute of Medical Sciences, New Delhi, India
| | - A Agarwal
- From the Department of Neurology, Cardioneurosciences Centre, All India Institute of Medical Sciences, New Delhi, India
| | - D M Radhakrishnan
- From the Department of Neurology, Cardioneurosciences Centre, All India Institute of Medical Sciences, New Delhi, India
| | - A K Srivastava
- From the Department of Neurology, Cardioneurosciences Centre, All India Institute of Medical Sciences, New Delhi, India
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10
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Gül Mert G, Özcan N, Hergüner Ö, Altunbaşak Ş, Incecik F, Bişgin A, Ceylaner S. Congenital myasthenic syndrome in Turkey: clinical and genetic features in the long-term follow-up of patients. Acta Neurol Belg 2021; 121:529-534. [PMID: 31773638 DOI: 10.1007/s13760-019-01246-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Accepted: 11/12/2019] [Indexed: 11/29/2022]
Abstract
Congenital Myasthenic Syndromes (CMS) are rare disorders that occur as a result of defects in the structure and in the function of neuromuscular junctions. Molecular genetic diagnosis is important to select the most suitable therapeutic option and treatment. Eight patients with congenital myasthenic syndromes who presented to the Çukurova University Pediatric Neurology Department Outpatient Clinic between June 2015 and May 2018 were reviewed. Mutations in the acetylcholine receptor (subunits in epsilon) (CHRNE) in three and mutations in the collagenic tail of endplate acetylcholinesterase (COLQ) gene in five patients were identified; p.W148 mutation was detected to be homozygous in four, c.1169A > G novel mutation in COLQ gene was homozygous in one, c452_454delAGG mutation was homozygous in the other patient, IVS7 + 2T > C(c.802 + 2T > C) mutation was homozygous in a patient and compound heterozygous mutations of c.865C > T(p.Leu289Phe) and c.872C > G(p.A2916)(p.Arg291Gly) in the CHRNE gene in the last patient. The parents of all the evaluated patients were consanguineous. Ptosis, ophthalmoplegia, generalized hypotonia, bulbar weakness, and respiratory crisis were the main findings at the time of presentation. Pyridostigmine is the first-line drug therapy in primary AChR deficiency. Beta adrenergic agonists, ephedrine, and albuterol are the other treatment options for CMS subtypes caused by mutations in COLQ. This study points out the genetic and phenotypic features of CMS patients in the Turkish population and it also reports previously unreported mutations in the literature. CHRNE and COLQ gene mutations are common in the Turkish population. Patients can get serious benefits and recover after the treatment. The treatment should be planned according to genetic tests and clinical findings.
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Affiliation(s)
- Gülen Gül Mert
- Department of Pediatrics, Division of Pediatric Neurology, Cukurova University, Adana, Turkey.
| | - Neslihan Özcan
- Department of Pediatrics, Division of Pediatric Neurology, Cukurova University, Adana, Turkey
| | - Özlem Hergüner
- Department of Pediatrics, Division of Pediatric Neurology, Cukurova University, Adana, Turkey
| | - Şakir Altunbaşak
- Department of Pediatrics, Division of Pediatric Neurology, Cukurova University, Adana, Turkey
| | - Faruk Incecik
- Department of Pediatrics, Division of Pediatric Neurology, Cukurova University, Adana, Turkey
| | - Atıl Bişgin
- Department of Medical Genetics, Cukurova University Faculty of Medicine, Adana, Turkey
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11
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Vidanagamage A, Gooneratne IK, Nandasiri S, Gunaratne K, Fernando A, Maxwell S, Cossins J, Beeson D, Chang T. A rare mutation in the COLQ gene causing congenital myasthenic syndrome with remarkable improvement to fluoxetine: A case report. Neuromuscul Disord 2021; 31:246-248. [PMID: 33487521 DOI: 10.1016/j.nmd.2020.12.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Revised: 10/02/2020] [Accepted: 12/04/2020] [Indexed: 11/18/2022]
Abstract
Congenital myasthenic syndromes (CMS) are genetically determined heterogenous disorders of neuromuscular transmission. We report a rare mutation of COLQ causing CMS in an Asian man that remarkably improved with fluoxetine. A 51-year-old Sri Lankan man with slowly progressive fatigable muscle weakness since eight years of age, presented with type 2 respiratory failure that required mechanical ventilation in the acute crisis and subsequent home-based non-invasive ventilation. His birth and family histories were unremarkable. On examination, he had limb girdle type of muscle weakness with fatigability and normal tendon reflexes with no ocular or bulbar involvement. DNA sequencing revealed a pathogenic homozygous mutation in COLQ gene: ENST00000383788.10:exon16:c.1228C>T:p.R410W, the first report in an Asian. Treatment with fluoxetine resulted in remarkable improvement and regain of muscle power and independence from assisted ventilation.
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Affiliation(s)
| | | | | | | | | | - Susan Maxwell
- Neuromuscular Disorders Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, Oxford OX3 9DS, UK
| | - Judith Cossins
- Neuromuscular Disorders Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, Oxford OX3 9DS, UK
| | - David Beeson
- Neuromuscular Disorders Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, Oxford OX3 9DS, UK
| | - Thashi Chang
- National Hospital of Sri Lanka, Colombo, Sri Lanka; Department of Clinical Medicine, Faculty of Medicine, University of Colombo, 25, Kynsey Road, Colombo 00800, Sri Lanka.
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12
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Desaphy JF, Altamura C, Vicart S, Fontaine B. Targeted Therapies for Skeletal Muscle Ion Channelopathies: Systematic Review and Steps Towards Precision Medicine. J Neuromuscul Dis 2021; 8:357-381. [PMID: 33325393 PMCID: PMC8203248 DOI: 10.3233/jnd-200582] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
BACKGROUND Skeletal muscle ion channelopathies include non-dystrophic myotonias (NDM), periodic paralyses (PP), congenital myasthenic syndrome, and recently identified congenital myopathies. The treatment of these diseases is mainly symptomatic, aimed at reducing muscle excitability in NDM or modifying triggers of attacks in PP. OBJECTIVE This systematic review collected the evidences regarding effects of pharmacological treatment on muscle ion channelopathies, focusing on the possible link between treatments and genetic background. METHODS We searched databases for randomized clinical trials (RCT) and other human studies reporting pharmacological treatments. Preclinical studies were considered to gain further information regarding mutation-dependent drug effects. All steps were performed by two independent investigators, while two others critically reviewed the entire process. RESULTS For NMD, RCT showed therapeutic benefits of mexiletine and lamotrigine, while other human studies suggest some efficacy of various sodium channel blockers and of the carbonic anhydrase inhibitor (CAI) acetazolamide. Preclinical studies suggest that mutations may alter sensitivity of the channel to sodium channel blockers in vitro, which has been translated to humans in some cases. For hyperkalemic and hypokalemic PP, RCT showed efficacy of the CAI dichlorphenamide in preventing paralysis. However, hypokalemic PP patients carrying sodium channel mutations may have fewer benefits from CAI compared to those carrying calcium channel mutations. Few data are available for treatment of congenital myopathies. CONCLUSIONS These studies provided limited information about the response to treatments of individual mutations or groups of mutations. A major effort is needed to perform human studies for designing a mutation-driven precision medicine in muscle ion channelopathies.
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Affiliation(s)
- Jean-François Desaphy
- Department of Biomedical Sciences and Human Oncology, School of Medicine, University of Bari Aldo Moro, Bari, Italy
| | - Concetta Altamura
- Department of Biomedical Sciences and Human Oncology, School of Medicine, University of Bari Aldo Moro, Bari, Italy
| | - Savine Vicart
- Sorbonne Université, INSERM, Assistance Publique Hôpitaux de Paris, Centre de Recherche en Myologie-UMR 974, Reference center in neuro-muscular channelopathies, Institute of Myology, Hôpital Universitaire Pitié-Salpêtrière, Paris, France
| | - Bertrand Fontaine
- Sorbonne Université, INSERM, Assistance Publique Hôpitaux de Paris, Centre de Recherche en Myologie-UMR 974, Reference center in neuro-muscular channelopathies, Institute of Myology, Hôpital Universitaire Pitié-Salpêtrière, Paris, France
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13
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Mroczek M, Durmus H, Töpf A, Parman Y, Straub V. Four Individuals with a Homozygous Mutation in Exon 1f of the PLEC Gene and Associated Myasthenic Features. Genes (Basel) 2020; 11:genes11070716. [PMID: 32605089 PMCID: PMC7397187 DOI: 10.3390/genes11070716] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2020] [Revised: 06/23/2020] [Accepted: 06/24/2020] [Indexed: 11/17/2022] Open
Abstract
We identified the known c.1_9del mutation in the PLEC gene in four unrelated females from consanguineous families of Turkish origin. All individuals presented with slowly progressive limb-girdle weakness without any dermatological findings, and dystrophic changes observed in their muscle biopsies. Additionally, the neurological examination revealed ptosis, facial weakness, fatigability, and muscle cramps in all four cases. In two patients, repetitive nerve stimulation showed a borderline decrement and a high jitter was detected in all patients by single-fiber electromyography. Clinical improvement was observed after treatment with pyridostigmine and salbutamol was started. We further characterize the phenotype of patients with limb-girdle muscular dystrophy R17 clinically, by muscle magnetic resonance imaging (MRI) features and by describing a common 3.8 Mb haplotype in three individuals from the same geographical region. In addition, we review the neuromuscular symptoms associated with PLEC mutations and the role of plectin in the neuromuscular junction.
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Affiliation(s)
- Magdalena Mroczek
- John Walton Muscular Dystrophy Research Centre, Translational and Clinical Research Institute, Newcastle University and Newcastle Hospitals NHS Foundation Trust, Newcastle upon Tyne NE1 3BZ, UK; (M.M.); (A.T.)
| | - Hacer Durmus
- Department of Neurology, Istanbul Faculty of Medicine, Istanbul University, Istanbul 34093, Turkey; (H.D.); (Y.P.)
| | - Ana Töpf
- John Walton Muscular Dystrophy Research Centre, Translational and Clinical Research Institute, Newcastle University and Newcastle Hospitals NHS Foundation Trust, Newcastle upon Tyne NE1 3BZ, UK; (M.M.); (A.T.)
| | - Yesim Parman
- Department of Neurology, Istanbul Faculty of Medicine, Istanbul University, Istanbul 34093, Turkey; (H.D.); (Y.P.)
| | - Volker Straub
- John Walton Muscular Dystrophy Research Centre, Translational and Clinical Research Institute, Newcastle University and Newcastle Hospitals NHS Foundation Trust, Newcastle upon Tyne NE1 3BZ, UK; (M.M.); (A.T.)
- Correspondence: ; Tel.: +44-19124-18762-8655
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14
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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] [What about the content of this article? (0)] [Affiliation(s)] [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.
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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
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15
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Affiliation(s)
- Hansashree Padmanabha
- Department of Pediatrics, Postgraduate Institute of Medical Education and Research, Chandigarh, India
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16
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Ohno K. [Studies on therapeutic strategies for congenital myasthenic syndromes.]. Clin Calcium 2017; 27:421-428. [PMID: 28232657] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Congenital myasthenic syndromes(CMS)are caused by germline mutations in genes encoding molecules expressed at the neuromuscular junction. Mutations have been identified in 25 genes. Clinical phenotypes and rational therapies widely vary depending on the defective genes. Drugs that are used for CMS include cholinesterase inhibitors, 3,4-diaminopyridine, effedrine, albuterol(salbutamol), acetazolamide, quinidine, fluoxetine, and atracurium. Some of these drugs have opposing effects. Specific drug is thus required for a specific disease mechanism. In addition, we are developing a novel therapeutic strategy that exploits the nerve sprouting activity of zonisamide for CMS.
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Affiliation(s)
- Kinji Ohno
- Neurogenetics, Nagoya University Graduate School of Medicine, Japan
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17
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O'Grady GL, Verschuuren C, Yuen M, Webster R, Menezes M, Fock JM, Pride N, Best HA, Benavides Damm T, Turner C, Lek M, Engel AG, North KN, Clarke NF, MacArthur DG, Kamsteeg EJ, Cooper ST. Variants in SLC18A3, vesicular acetylcholine transporter, cause congenital myasthenic syndrome. Neurology 2016; 87:1442-1448. [PMID: 27590285 PMCID: PMC5075972 DOI: 10.1212/wnl.0000000000003179] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Accepted: 06/17/2016] [Indexed: 12/15/2022] Open
Abstract
OBJECTIVE To describe the clinical and genetic characteristics of presynaptic congenital myasthenic syndrome secondary to biallelic variants in SLC18A3. METHODS Individuals from 2 families were identified with biallelic variants in SLC18A3, the gene encoding the vesicular acetylcholine transporter (VAChT), through whole-exome sequencing. RESULTS The patients demonstrated features seen in presynaptic congenital myasthenic syndrome, including ptosis, ophthalmoplegia, fatigable weakness, apneic crises, and deterioration of symptoms in cold water for patient 1. Both patients demonstrated moderate clinical improvement on pyridostigmine. Patient 1 had a broader phenotype, including learning difficulties and left ventricular dysfunction. Electrophysiologic studies were typical for a presynaptic defect. Both patients showed profound electrodecrement on low-frequency repetitive stimulation followed by a prolonged period of postactivation exhaustion. In patient 1, this was unmasked only after isometric contraction, a recognized feature of presynaptic disease, emphasizing the importance of activation procedures. CONCLUSIONS VAChT is responsible for uptake of acetylcholine into presynaptic vesicles. The clinical and electrographic characteristics of the patients described are consistent with previously reported mouse models of VAChT deficiency. These findings make it very likely that defects in VAChT due to variants in SLC18A3 are a cause of congenital myasthenic syndrome in humans.
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Affiliation(s)
- Gina L O'Grady
- From the Institute for Neuroscience and Muscle Research (G.L.O., M.Y., N.P., H.A.B., T.B.D., K.N.N., N.F.C., S.T.C.), Kids Research Institute, T.Y. Department of Neurology (M.M., R.W.), and Heart Centre for Children (C.T.), Children's Hospital at Westmead, Sydney; Discipline of Paediatrics and Child Health (G.L.O., M.M., H.A.B., K.N.N., N.F.C., S.T.C.), Faculty of Medicine, University of Sydney, Australia; Departments of Genetics (C.V.) and Child Neurology (J.M.F.), University of Groningen University Medical Center Groningen, the Netherlands; Analytic and Translational Genetics Unit (M.L., D.G.M.), Massachusetts General Hospital, Boston; Broad Institute of Harvard and Massachusetts Institute of Technology (M.L., D.G.M.), Cambridge; Department of Neurology (A.G.E.), Mayo Clinic, Rochester, MN; Murdoch Children's Research Institute (K.N.N.), Royal Children's Hospital, Victoria, Australia; and Department of Human Genetics (E.-J.K.), Radboud University Medical Center, Nijmegen, the Netherlands
| | - Corien Verschuuren
- From the Institute for Neuroscience and Muscle Research (G.L.O., M.Y., N.P., H.A.B., T.B.D., K.N.N., N.F.C., S.T.C.), Kids Research Institute, T.Y. Department of Neurology (M.M., R.W.), and Heart Centre for Children (C.T.), Children's Hospital at Westmead, Sydney; Discipline of Paediatrics and Child Health (G.L.O., M.M., H.A.B., K.N.N., N.F.C., S.T.C.), Faculty of Medicine, University of Sydney, Australia; Departments of Genetics (C.V.) and Child Neurology (J.M.F.), University of Groningen University Medical Center Groningen, the Netherlands; Analytic and Translational Genetics Unit (M.L., D.G.M.), Massachusetts General Hospital, Boston; Broad Institute of Harvard and Massachusetts Institute of Technology (M.L., D.G.M.), Cambridge; Department of Neurology (A.G.E.), Mayo Clinic, Rochester, MN; Murdoch Children's Research Institute (K.N.N.), Royal Children's Hospital, Victoria, Australia; and Department of Human Genetics (E.-J.K.), Radboud University Medical Center, Nijmegen, the Netherlands
| | - Michaela Yuen
- From the Institute for Neuroscience and Muscle Research (G.L.O., M.Y., N.P., H.A.B., T.B.D., K.N.N., N.F.C., S.T.C.), Kids Research Institute, T.Y. Department of Neurology (M.M., R.W.), and Heart Centre for Children (C.T.), Children's Hospital at Westmead, Sydney; Discipline of Paediatrics and Child Health (G.L.O., M.M., H.A.B., K.N.N., N.F.C., S.T.C.), Faculty of Medicine, University of Sydney, Australia; Departments of Genetics (C.V.) and Child Neurology (J.M.F.), University of Groningen University Medical Center Groningen, the Netherlands; Analytic and Translational Genetics Unit (M.L., D.G.M.), Massachusetts General Hospital, Boston; Broad Institute of Harvard and Massachusetts Institute of Technology (M.L., D.G.M.), Cambridge; Department of Neurology (A.G.E.), Mayo Clinic, Rochester, MN; Murdoch Children's Research Institute (K.N.N.), Royal Children's Hospital, Victoria, Australia; and Department of Human Genetics (E.-J.K.), Radboud University Medical Center, Nijmegen, the Netherlands
| | - Richard Webster
- From the Institute for Neuroscience and Muscle Research (G.L.O., M.Y., N.P., H.A.B., T.B.D., K.N.N., N.F.C., S.T.C.), Kids Research Institute, T.Y. Department of Neurology (M.M., R.W.), and Heart Centre for Children (C.T.), Children's Hospital at Westmead, Sydney; Discipline of Paediatrics and Child Health (G.L.O., M.M., H.A.B., K.N.N., N.F.C., S.T.C.), Faculty of Medicine, University of Sydney, Australia; Departments of Genetics (C.V.) and Child Neurology (J.M.F.), University of Groningen University Medical Center Groningen, the Netherlands; Analytic and Translational Genetics Unit (M.L., D.G.M.), Massachusetts General Hospital, Boston; Broad Institute of Harvard and Massachusetts Institute of Technology (M.L., D.G.M.), Cambridge; Department of Neurology (A.G.E.), Mayo Clinic, Rochester, MN; Murdoch Children's Research Institute (K.N.N.), Royal Children's Hospital, Victoria, Australia; and Department of Human Genetics (E.-J.K.), Radboud University Medical Center, Nijmegen, the Netherlands
| | - Manoj Menezes
- From the Institute for Neuroscience and Muscle Research (G.L.O., M.Y., N.P., H.A.B., T.B.D., K.N.N., N.F.C., S.T.C.), Kids Research Institute, T.Y. Department of Neurology (M.M., R.W.), and Heart Centre for Children (C.T.), Children's Hospital at Westmead, Sydney; Discipline of Paediatrics and Child Health (G.L.O., M.M., H.A.B., K.N.N., N.F.C., S.T.C.), Faculty of Medicine, University of Sydney, Australia; Departments of Genetics (C.V.) and Child Neurology (J.M.F.), University of Groningen University Medical Center Groningen, the Netherlands; Analytic and Translational Genetics Unit (M.L., D.G.M.), Massachusetts General Hospital, Boston; Broad Institute of Harvard and Massachusetts Institute of Technology (M.L., D.G.M.), Cambridge; Department of Neurology (A.G.E.), Mayo Clinic, Rochester, MN; Murdoch Children's Research Institute (K.N.N.), Royal Children's Hospital, Victoria, Australia; and Department of Human Genetics (E.-J.K.), Radboud University Medical Center, Nijmegen, the Netherlands
| | - Johanna M Fock
- From the Institute for Neuroscience and Muscle Research (G.L.O., M.Y., N.P., H.A.B., T.B.D., K.N.N., N.F.C., S.T.C.), Kids Research Institute, T.Y. Department of Neurology (M.M., R.W.), and Heart Centre for Children (C.T.), Children's Hospital at Westmead, Sydney; Discipline of Paediatrics and Child Health (G.L.O., M.M., H.A.B., K.N.N., N.F.C., S.T.C.), Faculty of Medicine, University of Sydney, Australia; Departments of Genetics (C.V.) and Child Neurology (J.M.F.), University of Groningen University Medical Center Groningen, the Netherlands; Analytic and Translational Genetics Unit (M.L., D.G.M.), Massachusetts General Hospital, Boston; Broad Institute of Harvard and Massachusetts Institute of Technology (M.L., D.G.M.), Cambridge; Department of Neurology (A.G.E.), Mayo Clinic, Rochester, MN; Murdoch Children's Research Institute (K.N.N.), Royal Children's Hospital, Victoria, Australia; and Department of Human Genetics (E.-J.K.), Radboud University Medical Center, Nijmegen, the Netherlands
| | - Natalie Pride
- From the Institute for Neuroscience and Muscle Research (G.L.O., M.Y., N.P., H.A.B., T.B.D., K.N.N., N.F.C., S.T.C.), Kids Research Institute, T.Y. Department of Neurology (M.M., R.W.), and Heart Centre for Children (C.T.), Children's Hospital at Westmead, Sydney; Discipline of Paediatrics and Child Health (G.L.O., M.M., H.A.B., K.N.N., N.F.C., S.T.C.), Faculty of Medicine, University of Sydney, Australia; Departments of Genetics (C.V.) and Child Neurology (J.M.F.), University of Groningen University Medical Center Groningen, the Netherlands; Analytic and Translational Genetics Unit (M.L., D.G.M.), Massachusetts General Hospital, Boston; Broad Institute of Harvard and Massachusetts Institute of Technology (M.L., D.G.M.), Cambridge; Department of Neurology (A.G.E.), Mayo Clinic, Rochester, MN; Murdoch Children's Research Institute (K.N.N.), Royal Children's Hospital, Victoria, Australia; and Department of Human Genetics (E.-J.K.), Radboud University Medical Center, Nijmegen, the Netherlands
| | - Heather A Best
- From the Institute for Neuroscience and Muscle Research (G.L.O., M.Y., N.P., H.A.B., T.B.D., K.N.N., N.F.C., S.T.C.), Kids Research Institute, T.Y. Department of Neurology (M.M., R.W.), and Heart Centre for Children (C.T.), Children's Hospital at Westmead, Sydney; Discipline of Paediatrics and Child Health (G.L.O., M.M., H.A.B., K.N.N., N.F.C., S.T.C.), Faculty of Medicine, University of Sydney, Australia; Departments of Genetics (C.V.) and Child Neurology (J.M.F.), University of Groningen University Medical Center Groningen, the Netherlands; Analytic and Translational Genetics Unit (M.L., D.G.M.), Massachusetts General Hospital, Boston; Broad Institute of Harvard and Massachusetts Institute of Technology (M.L., D.G.M.), Cambridge; Department of Neurology (A.G.E.), Mayo Clinic, Rochester, MN; Murdoch Children's Research Institute (K.N.N.), Royal Children's Hospital, Victoria, Australia; and Department of Human Genetics (E.-J.K.), Radboud University Medical Center, Nijmegen, the Netherlands
| | - Tatiana Benavides Damm
- From the Institute for Neuroscience and Muscle Research (G.L.O., M.Y., N.P., H.A.B., T.B.D., K.N.N., N.F.C., S.T.C.), Kids Research Institute, T.Y. Department of Neurology (M.M., R.W.), and Heart Centre for Children (C.T.), Children's Hospital at Westmead, Sydney; Discipline of Paediatrics and Child Health (G.L.O., M.M., H.A.B., K.N.N., N.F.C., S.T.C.), Faculty of Medicine, University of Sydney, Australia; Departments of Genetics (C.V.) and Child Neurology (J.M.F.), University of Groningen University Medical Center Groningen, the Netherlands; Analytic and Translational Genetics Unit (M.L., D.G.M.), Massachusetts General Hospital, Boston; Broad Institute of Harvard and Massachusetts Institute of Technology (M.L., D.G.M.), Cambridge; Department of Neurology (A.G.E.), Mayo Clinic, Rochester, MN; Murdoch Children's Research Institute (K.N.N.), Royal Children's Hospital, Victoria, Australia; and Department of Human Genetics (E.-J.K.), Radboud University Medical Center, Nijmegen, the Netherlands
| | - Christian Turner
- From the Institute for Neuroscience and Muscle Research (G.L.O., M.Y., N.P., H.A.B., T.B.D., K.N.N., N.F.C., S.T.C.), Kids Research Institute, T.Y. Department of Neurology (M.M., R.W.), and Heart Centre for Children (C.T.), Children's Hospital at Westmead, Sydney; Discipline of Paediatrics and Child Health (G.L.O., M.M., H.A.B., K.N.N., N.F.C., S.T.C.), Faculty of Medicine, University of Sydney, Australia; Departments of Genetics (C.V.) and Child Neurology (J.M.F.), University of Groningen University Medical Center Groningen, the Netherlands; Analytic and Translational Genetics Unit (M.L., D.G.M.), Massachusetts General Hospital, Boston; Broad Institute of Harvard and Massachusetts Institute of Technology (M.L., D.G.M.), Cambridge; Department of Neurology (A.G.E.), Mayo Clinic, Rochester, MN; Murdoch Children's Research Institute (K.N.N.), Royal Children's Hospital, Victoria, Australia; and Department of Human Genetics (E.-J.K.), Radboud University Medical Center, Nijmegen, the Netherlands
| | - Monkol Lek
- From the Institute for Neuroscience and Muscle Research (G.L.O., M.Y., N.P., H.A.B., T.B.D., K.N.N., N.F.C., S.T.C.), Kids Research Institute, T.Y. Department of Neurology (M.M., R.W.), and Heart Centre for Children (C.T.), Children's Hospital at Westmead, Sydney; Discipline of Paediatrics and Child Health (G.L.O., M.M., H.A.B., K.N.N., N.F.C., S.T.C.), Faculty of Medicine, University of Sydney, Australia; Departments of Genetics (C.V.) and Child Neurology (J.M.F.), University of Groningen University Medical Center Groningen, the Netherlands; Analytic and Translational Genetics Unit (M.L., D.G.M.), Massachusetts General Hospital, Boston; Broad Institute of Harvard and Massachusetts Institute of Technology (M.L., D.G.M.), Cambridge; Department of Neurology (A.G.E.), Mayo Clinic, Rochester, MN; Murdoch Children's Research Institute (K.N.N.), Royal Children's Hospital, Victoria, Australia; and Department of Human Genetics (E.-J.K.), Radboud University Medical Center, Nijmegen, the Netherlands
| | - Andrew G Engel
- From the Institute for Neuroscience and Muscle Research (G.L.O., M.Y., N.P., H.A.B., T.B.D., K.N.N., N.F.C., S.T.C.), Kids Research Institute, T.Y. Department of Neurology (M.M., R.W.), and Heart Centre for Children (C.T.), Children's Hospital at Westmead, Sydney; Discipline of Paediatrics and Child Health (G.L.O., M.M., H.A.B., K.N.N., N.F.C., S.T.C.), Faculty of Medicine, University of Sydney, Australia; Departments of Genetics (C.V.) and Child Neurology (J.M.F.), University of Groningen University Medical Center Groningen, the Netherlands; Analytic and Translational Genetics Unit (M.L., D.G.M.), Massachusetts General Hospital, Boston; Broad Institute of Harvard and Massachusetts Institute of Technology (M.L., D.G.M.), Cambridge; Department of Neurology (A.G.E.), Mayo Clinic, Rochester, MN; Murdoch Children's Research Institute (K.N.N.), Royal Children's Hospital, Victoria, Australia; and Department of Human Genetics (E.-J.K.), Radboud University Medical Center, Nijmegen, the Netherlands
| | - Kathryn N North
- From the Institute for Neuroscience and Muscle Research (G.L.O., M.Y., N.P., H.A.B., T.B.D., K.N.N., N.F.C., S.T.C.), Kids Research Institute, T.Y. Department of Neurology (M.M., R.W.), and Heart Centre for Children (C.T.), Children's Hospital at Westmead, Sydney; Discipline of Paediatrics and Child Health (G.L.O., M.M., H.A.B., K.N.N., N.F.C., S.T.C.), Faculty of Medicine, University of Sydney, Australia; Departments of Genetics (C.V.) and Child Neurology (J.M.F.), University of Groningen University Medical Center Groningen, the Netherlands; Analytic and Translational Genetics Unit (M.L., D.G.M.), Massachusetts General Hospital, Boston; Broad Institute of Harvard and Massachusetts Institute of Technology (M.L., D.G.M.), Cambridge; Department of Neurology (A.G.E.), Mayo Clinic, Rochester, MN; Murdoch Children's Research Institute (K.N.N.), Royal Children's Hospital, Victoria, Australia; and Department of Human Genetics (E.-J.K.), Radboud University Medical Center, Nijmegen, the Netherlands
| | - Nigel F Clarke
- From the Institute for Neuroscience and Muscle Research (G.L.O., M.Y., N.P., H.A.B., T.B.D., K.N.N., N.F.C., S.T.C.), Kids Research Institute, T.Y. Department of Neurology (M.M., R.W.), and Heart Centre for Children (C.T.), Children's Hospital at Westmead, Sydney; Discipline of Paediatrics and Child Health (G.L.O., M.M., H.A.B., K.N.N., N.F.C., S.T.C.), Faculty of Medicine, University of Sydney, Australia; Departments of Genetics (C.V.) and Child Neurology (J.M.F.), University of Groningen University Medical Center Groningen, the Netherlands; Analytic and Translational Genetics Unit (M.L., D.G.M.), Massachusetts General Hospital, Boston; Broad Institute of Harvard and Massachusetts Institute of Technology (M.L., D.G.M.), Cambridge; Department of Neurology (A.G.E.), Mayo Clinic, Rochester, MN; Murdoch Children's Research Institute (K.N.N.), Royal Children's Hospital, Victoria, Australia; and Department of Human Genetics (E.-J.K.), Radboud University Medical Center, Nijmegen, the Netherlands
| | - Daniel G MacArthur
- From the Institute for Neuroscience and Muscle Research (G.L.O., M.Y., N.P., H.A.B., T.B.D., K.N.N., N.F.C., S.T.C.), Kids Research Institute, T.Y. Department of Neurology (M.M., R.W.), and Heart Centre for Children (C.T.), Children's Hospital at Westmead, Sydney; Discipline of Paediatrics and Child Health (G.L.O., M.M., H.A.B., K.N.N., N.F.C., S.T.C.), Faculty of Medicine, University of Sydney, Australia; Departments of Genetics (C.V.) and Child Neurology (J.M.F.), University of Groningen University Medical Center Groningen, the Netherlands; Analytic and Translational Genetics Unit (M.L., D.G.M.), Massachusetts General Hospital, Boston; Broad Institute of Harvard and Massachusetts Institute of Technology (M.L., D.G.M.), Cambridge; Department of Neurology (A.G.E.), Mayo Clinic, Rochester, MN; Murdoch Children's Research Institute (K.N.N.), Royal Children's Hospital, Victoria, Australia; and Department of Human Genetics (E.-J.K.), Radboud University Medical Center, Nijmegen, the Netherlands
| | - Erik-Jan Kamsteeg
- From the Institute for Neuroscience and Muscle Research (G.L.O., M.Y., N.P., H.A.B., T.B.D., K.N.N., N.F.C., S.T.C.), Kids Research Institute, T.Y. Department of Neurology (M.M., R.W.), and Heart Centre for Children (C.T.), Children's Hospital at Westmead, Sydney; Discipline of Paediatrics and Child Health (G.L.O., M.M., H.A.B., K.N.N., N.F.C., S.T.C.), Faculty of Medicine, University of Sydney, Australia; Departments of Genetics (C.V.) and Child Neurology (J.M.F.), University of Groningen University Medical Center Groningen, the Netherlands; Analytic and Translational Genetics Unit (M.L., D.G.M.), Massachusetts General Hospital, Boston; Broad Institute of Harvard and Massachusetts Institute of Technology (M.L., D.G.M.), Cambridge; Department of Neurology (A.G.E.), Mayo Clinic, Rochester, MN; Murdoch Children's Research Institute (K.N.N.), Royal Children's Hospital, Victoria, Australia; and Department of Human Genetics (E.-J.K.), Radboud University Medical Center, Nijmegen, the Netherlands
| | - Sandra T Cooper
- From the Institute for Neuroscience and Muscle Research (G.L.O., M.Y., N.P., H.A.B., T.B.D., K.N.N., N.F.C., S.T.C.), Kids Research Institute, T.Y. Department of Neurology (M.M., R.W.), and Heart Centre for Children (C.T.), Children's Hospital at Westmead, Sydney; Discipline of Paediatrics and Child Health (G.L.O., M.M., H.A.B., K.N.N., N.F.C., S.T.C.), Faculty of Medicine, University of Sydney, Australia; Departments of Genetics (C.V.) and Child Neurology (J.M.F.), University of Groningen University Medical Center Groningen, the Netherlands; Analytic and Translational Genetics Unit (M.L., D.G.M.), Massachusetts General Hospital, Boston; Broad Institute of Harvard and Massachusetts Institute of Technology (M.L., D.G.M.), Cambridge; Department of Neurology (A.G.E.), Mayo Clinic, Rochester, MN; Murdoch Children's Research Institute (K.N.N.), Royal Children's Hospital, Victoria, Australia; and Department of Human Genetics (E.-J.K.), Radboud University Medical Center, Nijmegen, the Netherlands.
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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] [What about the content of this article? (0)] [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.
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Natera-de Benito D, Bestué M, Vilchez JJ, Evangelista T, Töpf A, García-Ribes A, Trujillo-Tiebas MJ, García-Hoyos M, Ortez C, Camacho A, Jiménez E, Dusl M, Abicht A, Lochmüller H, Colomer J, Nascimento A. Long-term follow-up in patients with congenital myasthenic syndrome due to RAPSN mutations. Neuromuscul Disord 2015; 26:153-9. [PMID: 26782015 DOI: 10.1016/j.nmd.2015.10.013] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Revised: 10/27/2015] [Accepted: 10/29/2015] [Indexed: 11/19/2022]
Abstract
Rapsyn (RAPSN) mutations are a common cause of postsynaptic congenital myasthenic syndromes. We present a comprehensive description of the clinical and molecular findings of ten patients with CMS due to mutations in RAPSN, mostly with a long-term follow-up. Two patients were homozygous and eight were heterozygous for the common p.Asn88Lys mutation. In three of the heterozygous patients we have identified three novel mutations (c.869T > C; p.Leu290Pro, c.1185delG; p.Thr396Profs*12, and c.358delC; p.Gln120Serfs*8). In our cohort, the RAPSN mutations lead to a relatively homogeneous phenotype, characterized by fluctuating ptosis, occasional bulbar symptoms, neck muscle weakness, and mild proximal muscle weakness with exacerbations precipitated by minor infections. Interestingly, episodic exacerbations continue to occur during adulthood. These were characterized by proximal limb girdle weakness and ptosis, and not so much by respiratory insufficiency after age 6. All patients presented during neonatal period and responded to cholinergic agonists. In most of the affected patients, additional use of 3,4-diaminopyridine resulted in significant clinical benefit. The disease course is stable except for intermittent worsening.
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Affiliation(s)
- D Natera-de Benito
- Department of Pediatrics, Hospital Universitario de Fuenlabrada, Madrid, Spain.
| | - M Bestué
- Department of Neurology, Hospital General San Jorge, Huesca, Spain
| | - J J Vilchez
- Department of Neurology, Hospital Universitari La Fe, Valencia, Spain
| | - T Evangelista
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne NE1 3BZ, UK
| | - A Töpf
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne NE1 3BZ, UK
| | - A García-Ribes
- Department of Pediatrics, Hospital Universitario Cruces, Bilbao, Spain
| | - M J Trujillo-Tiebas
- Department of Genetics, Hospital Universitario Fundación Jiménez Díaz, Madrid, Spain
| | - M García-Hoyos
- Department of Genetics, Instituto de Medicina Genómica, Valencia, Spain
| | - C Ortez
- Department of Neuromuscular Diseases, Hospital Sant Joan de Déu, Barcelona, Spain
| | - A Camacho
- Department of Pediatric Neurology, Hospital Universitario 12 de Octubre, Madrid, Spain
| | - E Jiménez
- Department of Pediatrics, Hospital Universitario Rey Juan Carlos, Madrid, Spain
| | - M Dusl
- Friedrich-Baur-Institute, Ludwig-Maximilians-University Munich, Munich 80336,Germany
| | - A Abicht
- Friedrich-Baur-Institute, Ludwig-Maximilians-University Munich, Munich 80336,Germany; Medical Genetics Center, Munich, Germany
| | - H Lochmüller
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne NE1 3BZ, UK
| | - J Colomer
- Department of Neuromuscular Diseases, Hospital Sant Joan de Déu, Barcelona, Spain
| | - A Nascimento
- Department of Neuromuscular Diseases, Hospital Sant Joan de Déu, Barcelona, Spain
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20
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Ohno K, Ito M, Kawakami Y, Ohtsuka K. Collagen Q is a key player for developing rational therapy for congenital myasthenia and for dissecting the mechanisms of anti-MuSK myasthenia gravis. J Mol Neurosci 2015; 53:359-61. [PMID: 24234034 DOI: 10.1007/s12031-013-0170-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2013] [Accepted: 10/31/2013] [Indexed: 11/28/2022]
Abstract
Acetylcholinesterase (AChE) at the neuromuscular junction (NMJ) is anchored to the synaptic basal lamina via a triple helical collagen Q (ColQ) in the form of asymmetric AChE (AChE/ColQ). We exploited the proprietary NMJ-targeting signals of ColQ to treat congenital myasthenia and to explore the mechanisms of autoimmune myasthenia gravis (MG). Mutations in COLQ cause congenital endplate AChE deficiency (CEAD). First, a single intravenous administration of adeno-associated virus serotype 8 (AAV8)-COLQ to Colq−/− mice normalized motor functions, synaptic transmission, and partly the NMJ ultrastructure. Additionally, injection of purified recombinant AChE/ColQ protein complex into gluteus maximus accumulated AChE in non-injected forelimbs. Second, MuSK antibody-positive MG accounts for 5-15 % of MG. In vitro overlay of AChE/ColQ to muscle sections of Colq−/− mice, as well as in vitro plate-binding of MuSK to ColQ, revealed thatMuSK-IgG blocks binding of ColQ to MuSK in a dose-dependent manner. Passive transfer of MuSK-IgG to wild-type mice markedly reduced the size and intensity of ColQ signals at NMJs. MuSK-IgG thus interferes with binding of ColQ to MuSK. Elucidation of molecular mechanisms of specific binding of ColQ to NMJ enabled us to ameliorate devastating myasthenic symptoms of Colq−/− mice and also to reveal underlying mechanisms of anti-MuSK-MG.
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Abstract
The congenital myasthenic syndromes (CMS) are a diverse group of genetic disorders caused by abnormal signal transmission at the motor endplate, a special synaptic contact between motor axons and each skeletal muscle fibre. Most CMS stem from molecular defects in the muscle nicotinic acetylcholine receptor, but they can also be caused by mutations in presynaptic proteins, mutations in proteins associated with the synaptic basal lamina, defects in endplate development and maintenance, or defects in protein glycosylation. The specific diagnosis of some CMS can sometimes be reached by phenotypic clues pointing to the mutated gene. In the absence of such clues, exome sequencing is a useful technique for finding the disease gene. Greater understanding of the mechanisms of CMS have been obtained from structural and electrophysiological studies of the endplate, and from biochemical studies. Present therapies for the CMS include cholinergic agonists, long-lived open-channel blockers of the acetylcholine receptor ion channel, and adrenergic agonists. Although most CMS are treatable, caution should be exercised as some drugs that are beneficial in one syndrome can be detrimental in another.
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Affiliation(s)
- Andrew G Engel
- Department of Neurology, Mayo Clinic, Rochester, MN, USA.
| | - Xin-Ming Shen
- Department of Neurology, Mayo Clinic, Rochester, MN, USA
| | - Duygu Selcen
- Department of Neurology, Mayo Clinic, Rochester, MN, USA
| | - Steven M Sine
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN, USA
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Witting N, Crone C, Duno M, Vissing J. Clinical and neurophysiological response to pharmacological treatment of DOK7 congenital myasthenia in an older patient. Clin Neurol Neurosurg 2015; 130:168-70. [PMID: 25625551 DOI: 10.1016/j.clineuro.2015.01.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Revised: 01/05/2015] [Accepted: 01/07/2015] [Indexed: 02/04/2023]
Affiliation(s)
- Nanna Witting
- Neuromuscular Research Unit and Department of Neurology 2081 Rigshospitalet, University of Copenhagen, 2100 Copenhagen, Denmark.
| | - Clarissa Crone
- Department of Neurophysiology 3061 Rigshospitalet, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Morten Duno
- Department of Clinical Genetics 4062 Rigshospitalet, University of Copenhagen, 2100 Copenhagen, Denmark
| | - John Vissing
- Neuromuscular Research Unit and Department of Neurology 2081 Rigshospitalet, University of Copenhagen, 2100 Copenhagen, Denmark
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Vrinten C, van der Zwaag AM, Weinreich SS, Scholten RJPM, Verschuuren JJGM. Ephedrine for myasthenia gravis, neonatal myasthenia and the congenital myasthenic syndromes. Cochrane Database Syst Rev 2014; 2014:CD010028. [PMID: 25515947 PMCID: PMC7387729 DOI: 10.1002/14651858.cd010028.pub2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
BACKGROUND Myasthenia is a condition in which neuromuscular transmission is affected by antibodies against neuromuscular junction components (autoimmune myasthenia gravis, MG; and neonatal myasthenia gravis, NMG) or by defects in genes for neuromuscular junction proteins (congenital myasthenic syndromes, CMSs). Clinically, some individuals seem to benefit from treatment with ephedrine, but its effects and adverse effects have not been systematically evaluated. OBJECTIVES To assess the effects and adverse effects of ephedrine in people with autoimmune MG, transient neonatal MG, and the congenital myasthenic syndromes. SEARCH METHODS On 17 November 2014, we searched the Cochrane Neuromuscular Disease Group Specialized Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE and EMBASE. We also searched reference lists of articles, conference proceedings of relevant conferences, and prospective trial registers. In addition, we contacted manufacturers and researchers in the field. SELECTION CRITERIA We considered randomised controlled trials (RCTs) and quasi-RCTs comparing ephedrine as a single or add-on treatment with any other active treatment, placebo, or no treatment in adults or children with autoimmune MG, NMG, or CMSs. DATA COLLECTION AND ANALYSIS Two review authors independently assessed study design and quality, and extracted data. We contacted study authors for additional information. We collected information on adverse effects from included articles, and contacted authors. MAIN RESULTS We found no RCTs or quasi-RCTs, and therefore could not establish the effect of ephedrine on MG, NMG and CMSs. We describe the results of 53 non-randomised studies narratively in the Discussion section, including observations of endurance, muscle strength and quality of life. Effects may differ depending on the type of myasthenia. Thirty-seven studies were in participants with CMS, five in participants with MG, and in 11 the precise form of myasthenia was unknown. We found no studies for NMG. Reported adverse effects included tachycardia, sleep disturbances, nervousness, and withdrawal symptoms. AUTHORS' CONCLUSIONS There was no evidence available from RCTs or quasi-RCTs, but some observations from non-randomised studies are available. There is a need for more evidence from suitable forms of prospective RCTs, such as series of n-of-one RCTs, that use appropriate and validated outcome measures.
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Affiliation(s)
- Charlotte Vrinten
- VU University Medical CenterCommunity Genetics Section, Clinical GeneticsBS7, D450PO Box 7057AmsterdamNetherlands1007 MB
| | - Angeli M van der Zwaag
- VU University Medical CenterCommunity Genetics Section, Clinical GeneticsBS7, D450PO Box 7057AmsterdamNetherlands1007 MB
| | - Stephanie S Weinreich
- VU University Medical CenterCommunity Genetics Section, Clinical GeneticsBS7, D450PO Box 7057AmsterdamNetherlands1007 MB
| | - Rob JPM Scholten
- Julius Center for Health Sciences and Primary Care / University Medical Center UtrechtDutch Cochrane CentreRoom Str. 6.126P.O. Box 85500UtrechtNetherlands3508 GA
| | - Jan JGM Verschuuren
- Leiden University Medical CenterDepartment of NeurologyPO Box 9600LeidenNetherlands2300 RC
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Nishikawa A, Mori-Yoshimura M, Okamoto T, Oya Y, Nakata T, Ohno K, Murata M. [Beneficial effects of 3,4-diaminopyridine in a 26-year-old woman with DOK7 congenital myasthenic syndrome who was originally diagnosed with facioscapulohumeral dystrophy]. Rinsho Shinkeigaku 2014; 54:561-564. [PMID: 25087557 DOI: 10.5692/clinicalneurol.54.561] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We report a 26-year-old woman who had respiratory dysfunction and muscle weakness at birth and was diagnosed with facioscapulohumeral dystrophy at the age of 5. The extent of muscle weakness fluctuated daily or weekly and deteriorated in menstrual periods. At the age of 12, she noted improvements in symptoms when taking procaterol hydrochloride and began to take it regularly. After that, her condition stabilized. At the age of 26, she visited our hospital presenting with ptosis, muscle weakness in the face, trunk, and proximal limbs, and easy fatigability. Serum CK was normal; anti-acetylcholine receptor and anti-muscle specific tyrosine kinase antibodies were negative. A repetitive stimulation test in the trapezius muscle showed a waning phenomenon. Gene analysis for congenital myasthenic syndrome (CMS) revealed a new mutation in the DOK7 gene; the diagnosis of CMS was confirmed. Her symptoms worsened with ambenonium chloride but improved with 3,4-diaminopyridine. Our findings suggest that daily or weekly fluctuation and worsening with a menses in muscle weakness is an important diagnostic feature of CMS.
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Affiliation(s)
- Atsuko Nishikawa
- Department of Neurology, National Center Hospital, National Center of Neurology and Psychiatry
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Webster R, Liu WW, Chaouch A, Lochmüller H, Beeson D. Fast-channel congenital myasthenic syndrome with a novel acetylcholine receptor mutation at the α-ε subunit interface. Neuromuscul Disord 2013; 24:143-7. [PMID: 24295813 DOI: 10.1016/j.nmd.2013.10.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2013] [Revised: 10/22/2013] [Accepted: 10/25/2013] [Indexed: 01/24/2023]
Abstract
Congenital myasthenic syndromes (CMS) result from the failure to achieve muscle depolarisation due to disorders in the structure and/or function of the neuromuscular synapse. Mutations of the nicotinic acetylcholine receptor (nAChR) form a major subset of CMS. We describe a patient who presented with recurrent apnoeic crises in the neonatal period requiring ventilator support. Electromyography revealed compound muscle action potential decrement upon repetitive stimulation. Sequencing of nAChR subunit genes revealed two missense mutations. One previously reported null mutation p.εTyr15His, and a second novel missense mutation, p.εThr38Lys, that is well expressed in mammalian cell culture and thus likely to exert its effect via alteration of ion channel kinetics. Functional analysis revealed abbreviated ion channel bursts characteristic of a fast channel CMS. The mutation p.εThr38Lys occurs at the interface between the α and ε subunits of the nAChR pentamer and leads to instability of the open channel. The effects of this mutation on channel function were investigated in relation to other fast channel mutants at an analogous subunit interface within the nAChR pentamer. Fast channel syndromes are frequently characterised by severe myasthenic weakness with apnoeic crises; knowledge of the underlying mutation and its functional consequences can be vital for appropriate therapy and patient management.
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Affiliation(s)
- Richard Webster
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Headley Way, Oxford, UK
| | - Wei-Wei Liu
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Headley Way, Oxford, UK
| | - Amina Chaouch
- Institute of Genetic Medicine, International Centre for Life, Newcastle upon Tyne, UK
| | - Hanns Lochmüller
- Institute of Genetic Medicine, International Centre for Life, Newcastle upon Tyne, UK
| | - David Beeson
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Headley Way, Oxford, UK.
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Gallenmüller C, Müller-Felber W, Dusl M, Stucka R, Guergueltcheva V, Blaschek A, von der Hagen M, Huebner A, Müller JS, Lochmüller H, Abicht A. Salbutamol-responsive limb-girdle congenital myasthenic syndrome due to a novel missense mutation and heteroallelic deletion in MUSK. Neuromuscul Disord 2013; 24:31-5. [PMID: 24183479 PMCID: PMC4018985 DOI: 10.1016/j.nmd.2013.08.002] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Revised: 07/20/2013] [Accepted: 08/01/2013] [Indexed: 12/24/2022]
Abstract
Congenital myasthenic syndromes (CMS) are clinically and genetically heterogeneous disorders characterized by a neuromuscular transmission defect. In recent years, causative mutations have been identified in atleast 15 genes encoding proteins of the neuromuscular junction. Mutations in MUSK are known as a very rare genetic cause of CMS and have been described in only three families, world-wide. Consequently, the knowledge about efficient drug therapy is very limited. We identified a novel missense mutation (p.Asp38Glu) heteroallelic to a genomic deletion affecting exons 2–3 of MUSK as cause of a limb-girdle CMS in two brothers of Turkish origin. Clinical symptoms included fatigable limb weakness from early childhood on. Upon diagnosis of a MUSK-related CMS at the age of 16 and 13 years, respectively, treatment with salbutamol was initiated leading to an impressive improvement of clinical symptoms, while treatment with esterase inhibitors did not show any benefit. Our findings highlight the importance of a molecular diagnosis in CMS and demonstrate considerable similarities between patients with MUSK and DOK7-related CMS in terms of clinical phenotype and treatment options.
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Affiliation(s)
| | | | - Marina Dusl
- Friedrich-Baur-Institut, Ludwig Maximilians University, Munich, Germany
| | - Rolf Stucka
- Friedrich-Baur-Institut, Ludwig Maximilians University, Munich, Germany
| | - Velina Guergueltcheva
- Friedrich-Baur-Institut, Ludwig Maximilians University, Munich, Germany; Clinic of Neurology, University Hospital Alexandrovska, Sofia, Bulgaria
| | - Astrid Blaschek
- Haunersche Kinderklinik, Ludwig Maximilians University, Munich, Germany
| | | | - Angela Huebner
- Children's Hospital, Technical University Dresden, Germany
| | - Juliane S Müller
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Hanns Lochmüller
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Angela Abicht
- Friedrich-Baur-Institut, Ludwig Maximilians University, Munich, Germany; Medical Genetics Center, Munich, Germany.
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27
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Nizamani NB, Talpur KI, Memon MN. Congenital myasthenia gravis. J Coll Physicians Surg Pak 2013; 23:517-518. [PMID: 23823963] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2011] [Accepted: 09/03/2012] [Indexed: 06/02/2023]
Abstract
Congenital myasthenia gravis is caused by genetic mutations affecting neuromuscular transmission, characterized by muscle weakness usually starting in childhood. A two and a half years old male child presented with bilateral ptosis and hoarseness of voice. The symptoms progressed giving the clinical impression of congenital myasthenia gravis. A series of tests were done including Ice Pack Test, acetylcholine receptor antibody test, trial of steroids and finally neostigmine test which confirmed the diagnosis. This case illustrates the challenges in diagnosing congenital myasthenia gravis and highlights the potential benefits of neostigmine test in its diagnosis.
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Affiliation(s)
- Noor Bakht Nizamani
- Department of Ophthalmology, Liaquat University of Medical and Health Sciences, Jamshoro, Hyderabad.
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Gajda A, Szabó H, Gergev G, Karcagi V, Szabó N, Endreffy E, Túri S, Sztriha L. Congenital myasthenic syndromes and transient myasthenia gravis. Ideggyogy Sz 2013; 66:200-203. [PMID: 23909021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Hypotonia in the neonatal period and early infancy is a common clinical finding. It can be caused by various heterogeneous disorders of different origin which might lead to diagnostic difficulties. Disorders of the neuromuscular junction, such as congenital myasthenic syndromes and neonatal transient myasthenia gravis are among the aetiologies. We report on a case of congenital myasthenia caused by mutation in the long cytoplasmic loop of the epsilon subunit of the acetylcholine receptor and a neonate of a myasthenic mother diagnosed with transient myasthenia gravis.
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Affiliation(s)
- Anna Gajda
- Department of Paediatrics, University of Szeged, Szeged.
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Burke G, Hiscock A, Klein A, Niks EH, Main M, Manzur AY, Ng J, de Vile C, Muntoni F, Beeson D, Robb S. Salbutamol benefits children with congenital myasthenic syndrome due to DOK7 mutations. Neuromuscul Disord 2012; 23:170-5. [PMID: 23219351 DOI: 10.1016/j.nmd.2012.11.004] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2012] [Revised: 09/25/2012] [Accepted: 11/06/2012] [Indexed: 01/06/2023]
Abstract
Congenital myasthenic syndromes due to DOK7 mutations cause fatigable limb girdle weakness. Treatment with ephedrine improves muscle strength. Salbutamol, a β(2)-adrenergic receptor agonist with fewer side effects and more readily available, has been effective in adult and anecdotal childhood cases. This study reports the effects of salbutamol on motor function in childhood DOK7 congenital myasthenic syndrome. Nine children (age range 5.9-15.1years) were treated with oral salbutamol, 2-4mg TDS. The effect on timed tests of motor function, pre- and up to 28months post-treatment, was audited retrospectively. All 9 reported functional benefit within 1month, with progressive improvement to a plateau at 12-18months. Within the first month, all 3 non-ambulant children resumed walking with assistance. Although improvements were seen in some timed tests (timed 10m, arm raise time, 6min walk time) this did not fully reflect the observed functional benefits in daily living activities. No major side effects were reported. We conclude that oral salbutamol treatment significantly improves strength in children with DOK7 congenital myasthenic syndrome and is well tolerated. Outcome measures need to be refined further, both to accurately reflect functional abilities in children and to document progress and treatment response.
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Affiliation(s)
- Georgina Burke
- Wessex Neurological Centre, Southampton General Hospital, Southampton, UK.
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30
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Palace J, Lashley D, Bailey S, Jayawant S, Carr A, McConville J, Robb S, Beeson D. Clinical features in a series of fast channel congenital myasthenia syndrome. Neuromuscul Disord 2011; 22:112-7. [PMID: 21940170 DOI: 10.1016/j.nmd.2011.08.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2011] [Revised: 07/29/2011] [Accepted: 08/02/2011] [Indexed: 11/19/2022]
Abstract
Fast channel congenital myasthenic syndromes are rare, but frequently result in severe weakness. We report a case of 12 fast channel patients to highlight clinical features and management difficulties. Patients were diagnosed through genetic screening and identification of mutations shown to cause fast channel syndrome. Data was obtained from clinical notes, history, examination and follow up. Patterns of muscle weakness involved limb, trunk, bulbar, respiratory, facial and extraocular muscles. Patients responded to treatment with anticholinesterase medication and 3,4-diaminopyridine. Fast channel syndrome contrasted with AChR deficiency in the occurrence of severe respiratory crises in infancy and childhood. The death of two children even when on treatment and the family histories of sibling deaths re-inforces the need for accurate genetic diagnosis, optimised pharmacological treatment and additional supportive measures to manage acute respiratory crises. Referral to a specialist paediatric respiratory centre and regular resuscitation training for parents are recommended.
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Jones AK, Rayes D, Al-Diwani A, Maynard TPR, Jones R, Hernando G, Buckingham SD, Bouzat C, Sattelle DB. A Cys-loop mutation in the Caenorhabditis elegans nicotinic receptor subunit UNC-63 impairs but does not abolish channel function. J Biol Chem 2011; 286:2550-8. [PMID: 20966081 PMCID: PMC3024750 DOI: 10.1074/jbc.m110.177238] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2010] [Revised: 09/24/2010] [Indexed: 11/06/2022] Open
Abstract
The nematode Caenorhabditis elegans is an established model organism for studying neurobiology. UNC-63 is a C. elegans nicotinic acetylcholine receptor (nAChR) α-subunit. It is an essential component of the levamisole-sensitive muscle nAChR (L-nAChR) and therefore plays an important role in cholinergic transmission at the nematode neuromuscular junction. Here, we show that worms with the unc-63(x26) allele, with its αC151Y mutation disrupting the Cys-loop, have deficient muscle function reflected by impaired swimming (thrashing). Single-channel recordings from cultured muscle cells from the mutant strain showed a 100-fold reduced frequency of opening events and shorter channel openings of L-nAChRs compared with those of wild-type worms. Anti-UNC-63 antibody staining in both cultured adult muscle and embryonic cells showed that L-nAChRs were expressed at similar levels in the mutant and wild-type cells, suggesting that the functional changes in the receptor, rather than changes in expression, are the predominant effect of the mutation. The kinetic changes mimic those reported in patients with fast-channel congenital myasthenic syndromes. We show that pyridostigmine bromide and 3,4-diaminopyridine, which are drugs used to treat fast-channel congenital myasthenic syndromes, partially rescued the motility defect seen in unc-63(x26). The C. elegans unc-63(x26) mutant may therefore offer a useful model to assist in the development of therapies for syndromes produced by altered function of human nAChRs.
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Affiliation(s)
- Andrew K. Jones
- From the Medical Research Council Functional Genomics Unit, Department of Physiology, Anatomy and Genetics, University of Oxford, South Parks Road, Oxford OX1 3QX, United Kingdom
| | - Diego Rayes
- the Instituto de Investigaciones Bioquímicas de Bahía Blanca, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas, B-8000FWB Bahía Blanca, Argentina, and
| | - Adam Al-Diwani
- From the Medical Research Council Functional Genomics Unit, Department of Physiology, Anatomy and Genetics, University of Oxford, South Parks Road, Oxford OX1 3QX, United Kingdom
| | - Thomas P. R. Maynard
- From the Medical Research Council Functional Genomics Unit, Department of Physiology, Anatomy and Genetics, University of Oxford, South Parks Road, Oxford OX1 3QX, United Kingdom
| | - Rachel Jones
- From the Medical Research Council Functional Genomics Unit, Department of Physiology, Anatomy and Genetics, University of Oxford, South Parks Road, Oxford OX1 3QX, United Kingdom
| | - Guillermina Hernando
- the Instituto de Investigaciones Bioquímicas de Bahía Blanca, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas, B-8000FWB Bahía Blanca, Argentina, and
| | - Steven D. Buckingham
- From the Medical Research Council Functional Genomics Unit, Department of Physiology, Anatomy and Genetics, University of Oxford, South Parks Road, Oxford OX1 3QX, United Kingdom
| | - Cecilia Bouzat
- the Instituto de Investigaciones Bioquímicas de Bahía Blanca, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas, B-8000FWB Bahía Blanca, Argentina, and
| | - David B. Sattelle
- the Faculty of Life Sciences, AV Hill Building, University of Manchester, Oxford Road, Manchester M13 9PT, United Kingdom
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Ceylan A, Tuncer O, Sayin R, Peker E, Caksen H, Sari S. Congenital myasthenic syndrome: a case report. Genet Couns 2011; 22:75-78. [PMID: 21614992] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Congenital myasthenic syndromes (CMS) are diseases of the neuromuscular junction. They usually belong to the disease groups that begin in the infantile or childhood period and carry genetic characteristics. The following is important in establishing the diagnosis of this disease: clinical findings, electromyography, genetic tests, determination of serum acetylcholine receptor antibodies. Acetylcholine esterase inhibitor drugs are used in treatment of CMS. A seven-month old male patient was brought to our department with the complaints of difficult breathing, falling of the eyelids and swallowing difficulty. With clinical and laboratory findings, he was diagnosed with congenital myasthenia and treatment was started. CMS should be suspected in patients with no pathological findings on the physical examination, and normal chest X-rays.
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Affiliation(s)
- A Ceylan
- Yuzuncu Yil University, Faculty of Medicine, Department of Pediatrics, Van, Turkey
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Yeung WL, Lam CW, Ng PC. Intra-familial variation in clinical manifestations and response to ephedrine in siblings with congenital myasthenic syndrome caused by novel COLQ mutations. Dev Med Child Neurol 2010; 52:e243-4. [PMID: 20370815 DOI: 10.1111/j.1469-8749.2010.03663.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Kaas B, Vaidya AR, Leatherman A, Schleidt S, Kohn RE. Technical report: exploring the basis of congenital myasthenic syndromes in an undergraduate course, using the model organism, Caenorhabditis elegans. Invert Neurosci 2010; 10:17-23. [PMID: 20431904 DOI: 10.1007/s10158-010-0101-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2010] [Accepted: 04/16/2010] [Indexed: 11/28/2022]
Abstract
Mutations affecting acetylcholine receptors have been causally linked to the development of congenital myasthenic syndromes (CMS) in humans resulting from neuromuscular transmission defects. In an undergraduate Molecular Neurobiology course, the molecular basis of CMS was explored through study of a Caenorhabditis elegans model of the disease. The nicotinic acetylcholine receptor (nAChR), located on the postsynaptic muscle cell membrane, contains a pentameric ring structure comprised of five homologous subunits. In the nematode C. elegans, unc-63 encodes an α subunit of nAChR. UNC-63 is required for the function of nAChR at the neuromuscular junction. Mutations in unc-63 result in defects in locomotion and egg-laying and may be used as models for CMS. Here, we describe the responses of four unc-63 mutants to the cholinesterase inhibitor pyridostigmine bromide (range 0.9-15.6 mM in this study), a treatment for CMS that mitigates deficiencies in cholinergic transmission by elevating synaptic ACh levels. Our results show that 15.6 mM pyridostigmine bromide enhanced mobility in two alleles, depressed mobility in one allele and in N2, while having no effect on the fourth allele. This indicates that while pyridostigmine bromide may be effective at ameliorating symptoms of CMS in certain cases, it may not be a suitable treatment for all individuals due to the diverse etiology of this disease. Students in the Molecular Neurobiology course enhanced their experience in scientific research by conducting an experiment designed to increase understanding of genetic defects of neurological function.
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Affiliation(s)
- Bonnie Kaas
- The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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Ishigaki K, Murakami T, Ito Y, Yanagisawa A, Kodaira K, Shishikura K, Suzuki H, Hirayama Y, Osawa M. [Treatment approach to congenital myasthenic syndrome in a patient with acetylcholine receptor deficiency]. No To Hattatsu 2009; 41:37-42. [PMID: 19172815] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Congenital myasthenic syndromes (CMS) are rare heterogeneous disorders of neurotransmission caused by genetic defects of neuromuscular junction molecules. While CMS patients have been reported worldwide, in Japan there have been only a few descriptions of adult CMS patients with acetylcholinesterase (AChE) deficiency and slow channel syndrome. Herein, we report a Japanese CMS patient with acetylcholine receptor (AChR) deficiency, diagnosed during childhood, and our treatment approach to the patient. This 13-year-old Japanese boy had had severe myasthenic symptoms since infancy. Ptosis, his first symptom, appeared at 5 months and nasal voice was recognized at 2 years of age. AchR and anti-muscle-specific tyrosine kinase (Musk) antibody remained negative. A positive tensilon test and decremental response on electromyogram supported the diagnosis of sero-negative myasthenia gravis. Despite thymectomy and strong immunosuppressive therapy including steroid pulse and FK 506, he gradually deteriorated and became wheelchair bound. Genetic analyses for AchR, Rapsyn, Musk and AChE were negative. At age 11 years, a muscle biopsy was performed in the deltoid muscle for neuromuscular junction sampling. Electron microscopic and confocal microscopic analysis of endplates showed almost complete loss of AChR and the diagnosis of CMS with AChR deficiency was confirmed. All immunosuppressive therapies were discontinued. Instead, we started Ubretide and 3,4-diaminopyridine (DAP) after obtaining informed consent. Although not approved in Japan for this use, 3,4-DAP is reportedly effective in refractory cases of CMS. The patient experienced no side effects. Despite all of the objective data were improving, his subjective symptoms and ADL remained poor. There are still many challenges in the treatment of the patient.
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Affiliation(s)
- Keiko Ishigaki
- Department of Pediatrics, Tokyo Women's Medical University, School of Medicine, Tokyo.
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Masuda A, Shen XM, Ito M, Matsuura T, Engel AG, Ohno K. hnRNP H enhances skipping of a nonfunctional exon P3A in CHRNA1 and a mutation disrupting its binding causes congenital myasthenic syndrome. Hum Mol Genet 2008; 17:4022-35. [PMID: 18806275 PMCID: PMC2638575 DOI: 10.1093/hmg/ddn305] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2008] [Revised: 09/01/2008] [Accepted: 09/17/2008] [Indexed: 12/28/2022] Open
Abstract
In humans and great apes, CHRNA1 encoding the muscle nicotinic acetylcholine receptor alpha subunit carries an inframe exon P3A, the inclusion of which yields a nonfunctional alpha subunit. In muscle, the P3A(-) and P3A(+) transcripts are generated in a 1:1 ratio but the functional significance and regulation of the alternative splicing remain elusive. An intronic mutation (IVS3-8G>A), identified in a patient with congenital myasthenic syndrome, disrupts an intronic splicing silencer (ISS) and results in exclusive inclusion of the downstream P3A exon. We found that the ISS-binding splicing trans-factor was heterogeneous nuclear ribonucleoprotein (hnRNP) H and the mutation attenuated the affinity of hnRNP for the ISS approximately 100-fold. We next showed that direct placement of hnRNP H to the 3' end of intron 3 silences, and siRNA-mediated downregulation of hnRNP H enhances recognition of exon P3A. Analysis of the human genome suggested that the hnRNPH-binding UGGG motif is overrepresented close to the 3' ends of introns. Pursuing this clue, we showed that alternative exons of GRIP1, FAS, VPS13C and NRCAM are downregulated by hnRNP H. Our findings imply that the presence of the hnRNP H-binding motif close to the 3' end of an intron is an essential but underestimated splicing regulator of the downstream exon.
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Affiliation(s)
- Akio Masuda
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Xin-Ming Shen
- Department of Neurology, Neuromuscular Research Laboratory, Mayo Clinic, Rochester, MN, USA
| | - Mikako Ito
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Tohru Matsuura
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Andrew G. Engel
- Department of Neurology, Neuromuscular Research Laboratory, Mayo Clinic, Rochester, MN, USA
| | - Kinji Ohno
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya, Japan
- Department of Neurology, Neuromuscular Research Laboratory, Mayo Clinic, Rochester, MN, USA
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Abstract
Congenital myasthenic syndromes (CMS) are classified in terms of the located defect: presynaptic, postsynaptic, and synaptic. They are inherited disorders caused by various genetic defects, all but the slow-channel CMS by recessive inheritance. To date, 10 different CMS are known and further CMS subtypes and their genetic cause may be disclosed by future investigations. Prognosis in CMS is variable and largely depends on the pathophysiological and genetic defect. Subtypes showing progression and life-threatening crises with apneas are generally less favorable than others. Therapeutic agents used in CMS depend on the underlying defect and include acetylcholinesterase inhibitor, 3,4-diaminopyridine, quinidine sulfate, fluoxetine, acetazolamide, and ephedrine. Although there are no double-blind, placebo-controlled clinical trials for CMS, several drugs have shown convincingly positive clinical effects. It is therefore necessary to start a rational therapy regime as early as possible. In most CMS, however, mild and severe clinical courses are reported, which makes assessment on an individual basis necessary. This review emphasizes therapeutic strategies in CMS.
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Affiliation(s)
- Ulrike Schara
- Department of Pediatric Neurology, University of Essen, Essen, Germany.
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Palace J, Lashley D, Newsom-Davis J, Cossins J, Maxwell S, Kennett R, Jayawant S, Yamanashi Y, Beeson D. Clinical features of the DOK7 neuromuscular junction synaptopathy. Brain 2007; 130:1507-15. [PMID: 17452375 DOI: 10.1093/brain/awm072] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Mutations in DOK7 have recently been shown to underlie a recessive congenital myasthenic syndrome (CMS) associated with small simplified neuromuscular junctions ('synaptopathy') but normal acetylcholine receptor and acetylcholinesterase function. We identified DOK7 mutations in 27 patients from 24 kinships. Mutation 1124_1127dupTGCC was common, present in 20 out of 24 kinships. All patients were found to have at least one allele with a frameshift mutation in DOK7 exon 7, suggesting that loss of function(s) associated with the C-terminal region of Dok-7 underlies this disorder. In 15 patients, we were able to study the clinical features in detail. Clinical onset was usually characterized by difficulty in walking developing after normal motor milestones. Proximal muscles were usually more affected than distal, leading to a 'limb-girdle' pattern of weakness; although ptosis was often present from an early age, eye movements were rarely involved. Patients did not show long-term benefit from anticholinesterase medication and sometimes worsened, and where tried responded to ephedrine. The phenotype can be distinguished from 'limb-girdle' myasthenia associated with tubular aggregates, where DOK7 mutations were not detected and patients respond to anticholinesterase treatments. CMS due to DOK7 mutations are common within our UK cohort and is likely to be under-diagnosed; recognition of the phenotype will help clinical diagnosis, targeted genetic screening and appropriate management.
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Affiliation(s)
- Jacqueline Palace
- Neurosciences Group, Weatherall Institute of Molecular Medicine, University of Oxford, OX3 9DS, UK
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Müller JS, Herczegfalvi A, Vilchez JJ, Colomer J, Bachinski LL, Mihaylova V, Santos M, Schara U, Deschauer M, Shevell M, Poulin C, Dias A, Soudo A, Hietala M, Aärimaa T, Krahe R, Karcagi V, Huebner A, Beeson D, Abicht A, Lochmüller H. Phenotypical spectrum of DOK7 mutations in congenital myasthenic syndromes. Brain 2007; 130:1497-506. [PMID: 17439981 DOI: 10.1093/brain/awm068] [Citation(s) in RCA: 114] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Dok ('downstream-of-kinase') family of cytoplasmic proteins play a role in signalling downstream of receptor and non-receptor phosphotyrosine kinases. Recently, a skeletal muscle receptor tyrosine kinase (MuSK)-interacting cytoplasmic protein termed Dok-7 has been identified. Subsequently, we and others identified mutations in DOK7 as a cause of congenital myasthenic syndromes (CMS), providing evidence for a crucial role of Dok-7 in maintaining synaptic structure. Here we present clinical and molecular genetic data of 14 patients from 12 independent kinships with 13 different mutations in the DOK7 gene. The clinical picture of CMS with DOK7 mutations is highly variable. The age of onset may vary between birth and the third decade. However, most of the patients display a characteristic 'limb-girdle' pattern of weakness with a waddling gait and ptosis, but without ophthalmoparesis. Respiratory problems were frequent. Patients did not benefit from long-term therapy with esterase inhibitors; some of the patients even worsened. DOK7 mutations have emerged as one of the major genetic defects in CMS. The clinical picture differs significantly from CMS caused by mutations in other genes, such as the acetylcholine receptor (AChR) subunit genes. None of the patients with DOK7 mutations had tubular aggregates in the muscle biopsy, implying that 'limb-girdle myasthenia (LGM) with tubular aggregates' previously described in literature may be a pathogenic entity distinct from CMS caused by DOK7 mutations.
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MESH Headings
- Adolescent
- Adult
- Biopsy
- Child
- Child, Preschool
- Cholinesterase Inhibitors/adverse effects
- Cholinesterase Inhibitors/therapeutic use
- DNA Mutational Analysis/methods
- Electric Stimulation
- Female
- Gait Disorders, Neurologic/genetics
- Humans
- Male
- Middle Aged
- Muscle Proteins/genetics
- Muscle, Skeletal/pathology
- Muscular Dystrophies, Limb-Girdle/drug therapy
- Muscular Dystrophies, Limb-Girdle/genetics
- Muscular Dystrophies, Limb-Girdle/pathology
- Mutation
- Myasthenic Syndromes, Congenital/drug therapy
- Myasthenic Syndromes, Congenital/genetics
- Myasthenic Syndromes, Congenital/pathology
- Phenotype
- Polymorphism, Restriction Fragment Length
- Treatment Failure
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Affiliation(s)
- Juliane S Müller
- Friedrich-Baur-Institute, Department of Neurology, Ludwig-Maximilians-University, Munich, Germany
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40
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Lorenzoni PJ, Kay CSK, Arruda WO, Scola RH, Werneck LC. Estudo neurofisiológico na síndrome miastênica congênita do canal lento: relato de caso. Arq Neuro-Psiquiatr 2006; 64:318-21. [PMID: 16791378 DOI: 10.1590/s0004-282x2006000200028] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A síndrome do canal lento é uma das síndromes miastênicas congênitas atribuída a desordem dinâmica do canal iônico do receptor de acetilcolina da junção neuromuscular. Descrevemos o caso de um homem de 25 anos com progressiva ptose palpebral e limitação da movimentação ocular desde infância, que evoluiu há 6 anos com piora da oftalmoparesia externa e diminuição da força muscular em ombros e mãos. O estudo da condução nervosa motora após estímulo único demonstrou duplo potencial de ação muscular composto (PAMC) com desaparecimento do segundo após esforço de 30 segundos. Ao estímulo repetitivo dos nervos facial e acessório observou-se um decremento da amplitude do PAMC maior que 10% com desaparecimento do segundo potencial. O paciente fez uso de fluoxetina mostrando discreta melhora da força muscular, porém persiste com: ptose palpebral, limitação dos movimentos oculares e PAMC repetitivo ao estudo da condução nervosa motora. As características da doença são discutidas.
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Affiliation(s)
- Paulo José Lorenzoni
- Serviço de Doenças Neuromusculares, Hospital de Clínicas, Universidade Federal do Paraná, Curitiba, PR, Brazil
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Colomer J, Müller JS, Vernet A, Nascimento A, Pons M, Gonzalez V, Abicht A, Lochmüller H. Long-term improvement of slow-channel congenital myasthenic syndrome with fluoxetine. Neuromuscul Disord 2006; 16:329-33. [PMID: 16621558 DOI: 10.1016/j.nmd.2006.02.009] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2005] [Revised: 12/20/2005] [Accepted: 02/24/2006] [Indexed: 10/24/2022]
Abstract
We report on a 15-year-old patient who was diagnosed with congenital myasthenic syndrome (CMS) at the age of 7 months. At initial diagnosis, the CMS was not further characterized. The patient was treated for several years with the anticholinesterase drug (Mestinon), without clinical benefit. The patient deteriorated progressively and became dependent on home nocturnal ventilatory support, being unable to take part in daily life activities at age of 12 years. At age 14, the slow-channel syndrome mutation CHRNE L269F (805C>T) was detected and acetylcholinesterase inhibitor therapy was immediately stopped. Fluoxetine therapy was started and gradually increased over 2 months. The boy improved dramatically in strength and endurance and was taken off ventilatory support 1 month after the fluoxetine therapy was initiated. The clinical improvement was confirmed by functional respiratory and electrophysiological tests.
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MESH Headings
- Adolescent
- Cholinesterase Inhibitors/adverse effects
- DNA Mutational Analysis
- Dose-Response Relationship, Drug
- Drug Administration Schedule
- Fluoxetine/administration & dosage
- Genetic Predisposition to Disease/genetics
- Humans
- Male
- Muscle, Skeletal/innervation
- Muscle, Skeletal/pathology
- Muscle, Skeletal/physiopathology
- Mutation/genetics
- Myasthenic Syndromes, Congenital/diagnosis
- Myasthenic Syndromes, Congenital/drug therapy
- Myasthenic Syndromes, Congenital/genetics
- Neuromuscular Junction/drug effects
- Neuromuscular Junction/metabolism
- Neuromuscular Junction/physiopathology
- Receptors, Cholinergic/drug effects
- Receptors, Cholinergic/genetics
- Receptors, Cholinergic/metabolism
- Receptors, Nicotinic/genetics
- Recovery of Function/drug effects
- Recovery of Function/genetics
- Selective Serotonin Reuptake Inhibitors/administration & dosage
- Time
- Treatment Outcome
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Affiliation(s)
- J Colomer
- Unitat de Patologia Neuromuscular, Servei de Neurologia, Hospital Sant Joan de Déu,2 08950 Esplugues, Barcelona, Spain.
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Pelufo-Pellicer A, Monte-Boquet E, Romá-Sánchez E, Casanova-Sorní C, Poveda-Andrés JL. Fetal exposure to 3,4-diaminopyridine in a pregnant woman with congenital myasthenia syndrome. Ann Pharmacother 2006; 40:762-6. [PMID: 16537815 DOI: 10.1345/aph.1g166] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
OBJECTIVE To report a case of fetal exposure to pyridostigmine and 3,4-diaminopyridine (3,4-DAP) in a pregnant woman with congenital myasthenia syndrome (CMS). CASE SUMMARY A 31-year-old woman with postsynaptic CMS, not genetically characterized, was being treated with pyridostigmine and 3,4-DAP. She decided to become pregnant, despite having been informed about the paucity of available information on the possible risks of these drugs for the fetus. The dose of pyridostigmine remained stable throughout the pregnancy (60 mg every 8 h), and the 3,4-DAP dose was adjusted according to the patient's level of fatigue (20 mg/day, with occasional additional doses of 5 mg). At 25 weeks' gestation, ultrasonography confirmed the presence of only one umbilical artery. The results of other tests were normal. At 38 weeks' gestation, a healthy male neonate was born. His APGAR scores were 9 and 10 at 1 and 5 minutes, respectively. Five months later, the infant was healthy and his pediatric progress had been uneventful. DISCUSSION It was difficult to find information about the possible congenital defects related to the use of 3,4-DAP because it is a rarely used drug. This case attracted our interest because it is an uncommon disease, and we found no reports on the use of 3,4-DAP during pregnancy. To our knowledge, as of this writing, this is the first published report of the use of 3,4-DAP during pregnancy. CONCLUSIONS A successful pregnancy with a healthy infant was achieved after fetal exposure to 3,4-DAP and pyridostigmine.
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Bestue-Cardiel M, Sáenz de Cabezón-Alvarez A, Capablo-Liesa JL, López-Pisón J, Peña-Segura JL, Martin-Martinez J, Engel AG. Congenital endplate acetylcholinesterase deficiency responsive to ephedrine. Neurology 2005; 65:144-6. [PMID: 16009904 DOI: 10.1212/01.wnl.0000167132.35865.31] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The authors describe two patients with congenital myasthenic syndrome (CMS) with end plate acetylcholinesterase (AChE) deficiency caused by mutations in the collagenic tail (ColQ) of AChE: a homozygous C-terminal Y230S mutation in Patient 1 and Y430S and a C-terminal splice-site mutation in Patient 2. In Patient 1, a Prostigmin (neostigmine bromide) test failed to distinguish between AChE deficiency and a slow-channel CMS. Both patients responded dramatically to ephedrine therapy.
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Affiliation(s)
- M Bestue-Cardiel
- Department of Neurology, Miguel Servet Hospital, Zaragoza, Spain.
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Burke G, Cossins J, Maxwell S, Robb S, Nicolle M, Vincent A, Newsom-Davis J, Palace J, Beeson D. Distinct phenotypes of congenital acetylcholine receptor deficiency. Neuromuscul Disord 2004; 14:356-64. [PMID: 15145336 DOI: 10.1016/j.nmd.2004.03.005] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2004] [Revised: 03/23/2004] [Accepted: 03/23/2004] [Indexed: 10/26/2022]
Abstract
We contrast the phenotypes associated with hereditary acetylcholine receptor deficiency arising from mutations in either the acetylcholine receptor epsilon subunit or the endplate acetylcholine receptor clustering protein rapsyn. Mutational screening was performed by amplification of promoter and coding regions by PCR and direct DNA sequencing. We identified mutations in 37 acetylcholine receptor deficiency patients; 18 had acetylcholine receptor-epsilon mutations, 19 had rapsyn mutations. Mutated acetylcholine receptor-epsilon associated with bulbar symptoms, ptosis and ophthalmoplegia at birth, and generalized weakness. Mutated rapsyn caused either an early onset (rapsyn-EO) or late onset (rapsyn-LO) phenotype. Rapsyn-EO associated with arthrogryposis and life-threatening exacerbations during early childhood. Rapsyn-LO presented with limb weakness in adolescence or adulthood resembling seronegative myasthenia gravis. Awareness of distinct phenotypic features of acetylcholine receptor deficiency resulting from acetylcholine receptor-epsilon or rapsyn mutations should facilitate targeted genetic diagnosis, avoid inappropriate immunological therapy and, in some infants, prompt the rapid introduction of treatment that could be life saving.
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MESH Headings
- 4-Aminopyridine/analogs & derivatives
- 4-Aminopyridine/therapeutic use
- Adolescent
- Adult
- Aged
- Amifampridine
- Cell Line
- Child
- Child, Preschool
- Cholinesterase Inhibitors/therapeutic use
- DNA Mutational Analysis/methods
- Drug Therapy, Combination
- Electric Stimulation
- Electromyography/methods
- Electrophysiology/methods
- Embryo, Mammalian
- Ephedrine/therapeutic use
- Evoked Potentials, Motor/drug effects
- Evoked Potentials, Motor/radiation effects
- Female
- Fluorescent Antibody Technique/methods
- Humans
- Kidney
- Male
- Middle Aged
- Muscle Proteins/genetics
- Muscles
- Mutation/genetics
- Myasthenic Syndromes, Congenital/classification
- Myasthenic Syndromes, Congenital/drug therapy
- Myasthenic Syndromes, Congenital/genetics
- Myasthenic Syndromes, Congenital/physiopathology
- Phenotype
- Potassium Channel Blockers/therapeutic use
- Protein Subunits/deficiency
- Protein Subunits/genetics
- Pyridostigmine Bromide/therapeutic use
- RNA, Messenger/biosynthesis
- Receptors, Cholinergic/deficiency
- Receptors, Cholinergic/genetics
- Reverse Transcriptase Polymerase Chain Reaction/methods
- Sequence Analysis, DNA/methods
- Severity of Illness Index
- Sympathomimetics/therapeutic use
- Transfection/methods
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Affiliation(s)
- G Burke
- Department of Clinical Neurology, Radcliffe Infirmary, Oxford, UK
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Abstract
Congenital Myasthenic Syndromes (CMS) are a heterogeneous group of diseases caused by genetic defects affecting neuromuscular transmission. The twenty five past Years saw major advances in identifying different types of CMS due to abnormal presynaptic, synaptic, and postsynaptic proteins. CMS diagnosis requires two steps: 1) positive diagnosis supported by myasthenic signs beginning in neonatal period, efficacy of anticholinesterase medications, positive family history, negative tests for anti-acetylcholine receptor (AChR) antibodies, electromyographic studies (decremental response at low frequency, repetitive CMAP after one single stimulation); 2) pathophysiological characterisation of CMS implying specific studies: light and electron microscopic analysis of endplate (EP) morphology, estimation of the number of AChR per EP, acetylcholinesterase (AChE) expression, molecular genetic analysis. Most CMS are postsynaptic due to mutations in the AChR subunits genes that alter the kinetic properties or decrease the expression of AChR. The kinetic mutations increase or decrease the synaptic response to ACh resulting respectively in Slow Channel Syndrome (characterized by a autosomal dominant transmission, repetitive CMAP, refractoriness to anticholinesterase medication) and fast channel, recessively transmitted. AChR deficiency without kinetic abnormalities is caused by recessive mutations in AChR genes (mostly epsilon subunit) or by primary rapsyn deficiency, a post synaptic protein involved in AChR concentration. Recently, mutations in SCN4A sodium channel have been reported in one patient. AChE deficiency is identified on the following data: recessive transmission, presence of repetitive CMAP, refractoriness to cholinesterase inhibitors, slow pupillary response to light and absent expression of the enzyme at EP. This synaptic CMS is caused by mutations in the collagenic tail subunit (ColQ) that anchors the catalytic subunits in the synaptic basal lamina. The most frequent presynaptic CMS is caused by mutations of choline acetyltransferase. Several CMS are still not characterized. Many EP molecules are potential etiological candidates. In these unidentified cases, other methods of investigations are required: linkage analysis, when sufficient number of informative relatives are available, microelectrophysiological studies performed in intercostal or anconeus muscles. Prognosis of CMS, depending on severity and evolution of symptoms, is difficult to assess, and it cannot not be simply derived from mutation identification. Most patients respond favourably to anticholinesterase medications or to 3,4 DAP which is effective not only in presynaptic but also in postsynaptic CMS. Specific therapies for slow channel CMS are quinidine and fluoxetine that normalize the prolonged opening episodes. Clinical benefits derived from the full characterisation of each case include genetic counselling and specific therapy.
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Affiliation(s)
- F Andreux
- INSERM 582 et Institut de Myologie, Hôpital de la Pitié-Salpêtrière
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46
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Banwell BL, Ohno K, Sieb JP, Engel AG. Novel truncating RAPSN mutations causing congenital myasthenic syndrome responsive to 3,4-diaminopyridine. Neuromuscul Disord 2004; 14:202-7. [PMID: 15036330 DOI: 10.1016/j.nmd.2003.11.004] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2003] [Revised: 10/30/2003] [Accepted: 11/03/2003] [Indexed: 11/28/2022]
Abstract
Rapsyn is essential for clustering the acetylcholine receptor at the postsynaptic membrane of the neuromuscular junction. Direct sequencing of RAPSN in two children with congenital myasthenic syndromes with no mutation in any of the AChR subunits identified two heterozygous recessive mutations in each: a previously characterized N88K mutation in both, and a second frameshifting mutation in Patient (Pt) 1 and a nonsense mutation in Pt 2. An intercostal muscle biopsy in Pt 1 revealed decreased AChRs per endplate and decreased amplitude of the miniature endplate potential, predicted consequences of rapsyn deficiency. Clinically, both children manifested with hypomotility in utero, fatigable ocular and limb weakness since birth, decreased strength during viral illness, decremental response on electromyography, and absence of AChR antibodies. Pt 1, however, had a more severe clinical course with recurrent episodes of respiratory failure, contractures, and craniofacial malformations. In both patients, treatment with pyridostigmine was of some benefit, but the addition of 3,4-diaminopyridine led to significant clinical improvement. Thus, rapsyn deficiency predicting similar consequences at the cellular level can result in phenotypes with marked differences in severity of symptoms, risk of respiratory failure, and presence of contractures and craniofacial malformations.
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Affiliation(s)
- Brenda L Banwell
- Department of Pediatrics (Neurology), The Hospital for Sick Children, University of Toronto, Canada
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47
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Gurnett CA, Bodnar JA, Neil J, Connolly AM. Congenital myasthenic syndrome: presentation, electrodiagnosis, and muscle biopsy. J Child Neurol 2004; 19:175-82. [PMID: 15119478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 03/02/2023]
Abstract
We report 10 children with congenital myasthenic syndromes diagnosed by clinical features, electrodiagnostic studies, and response to acetylcholinesterase inhibitors. Age at diagnosis (mean = 4.4 years; range 0.2-10 years) correlated with age fatigue was recognized. Symptoms at presentation included mild gross motor development delay (7/10), speech articulation difficulty (5/10), and respiratory and feeding difficulties resulting in poor growth in 7 of 10 children. None of the five children with possible presynaptic abnormalities had decremental compound muscle action potential responses to 2 Hz repetitive nerve stimulation. Instead, electrodiagnostic studies showed a more than 100% increment of compound muscle action potential amplitude during 50 Hz repetitive nerve stimulation in two children and sustained compound muscle action potential decrement to 2 Hz repetitive nerve stimulation after depletion (10 Hz stimulation for 10 min) in four children. Muscle biopsies (n = 7) showed mild to severe variation in fiber size. Our experience suggests that many children with congenital myasthenic syndromes might be undiagnosed because of atypical presentation and because additional electrophysiologic studies are required.
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Affiliation(s)
- Christina A Gurnett
- Department of Neurology, Washington University School of Medicine, Saint Louis, MO 63110, USA
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48
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Abstract
The authors found that fluoxetine significantly shortens at 5 microM/L and nearly normalizes at 10 microM/L the prolonged opening bursts of slow-channel congenital myasthenic syndrome (SCCMS) acetylcholine receptors (AChR) expressed in fibroblasts. Prompted by this observation, they treated two SCCMS patients allergic to quinidine with up to 80 to 120 mg of fluoxetine per day over 3 years (serum fluoxetine + norfluoxetine levels 8 to 11 microM/L). Both patients showed marked subjective and objective improvement by quantitative muscle strength testing and electromyography.
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Affiliation(s)
- C Michel Harper
- Department of Neurology, Mayo Clinic, Rochester, MN 55905, USA.
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49
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Byring RF, Ohno K, Pihko H, Gustafsson B, Hackman P, Engel A, Udd B. [Respiratory arrests caused by congenital myasthenia gravis syndrome]. Duodecim 2003; 118:2323-6. [PMID: 12523110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/28/2023]
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50
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Zeevaert B, Hansen I, Crielaard JM, Wang FC. [Slow channel syndrome due to an autosomal translocation at 2q31-9p27]. Rev Neurol (Paris) 2002; 158:605-8. [PMID: 12072832] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/25/2023]
Abstract
A 27-year-old man complained of cervicoscapular and forearm weakness and amyotrophy. Electromyographic evaluation showed neuromuscular transmission dysfunction and a repetitive compound muscle action potential to a single stimulus. Prostigmine did not improve neuromuscular transmission. The genetic analysis of the patient's lymphocytes demonstrated a chromosomic 2q31-9p27 translocation. The combination of the clinical and electrophysiological data as well as the lack of auto-immunity signs against neuromuscular junction constituents led to the diagnosis to congenital postsynaptic myasthenic syndrome also called slow channel syndrome. This congenital myasthenic syndrome is for the first time associated with an autosomal translocation 2q31-9p27.
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MESH Headings
- Action Potentials
- Adult
- Autoimmune Diseases/diagnosis
- Chromosomes, Human, Pair 2/genetics
- Chromosomes, Human, Pair 2/ultrastructure
- Chromosomes, Human, Pair 9/genetics
- Chromosomes, Human, Pair 9/ultrastructure
- Diagnosis, Differential
- Electromyography
- Genetic Heterogeneity
- Humans
- In Situ Hybridization, Fluorescence
- Ion Transport
- Male
- Muscarinic Antagonists/therapeutic use
- Myasthenia Gravis/diagnosis
- Myasthenic Syndromes, Congenital/diagnosis
- Myasthenic Syndromes, Congenital/drug therapy
- Myasthenic Syndromes, Congenital/genetics
- Neostigmine
- Neural Conduction
- Protein Subunits
- Quinidine/therapeutic use
- Receptors, Muscarinic/genetics
- Receptors, Muscarinic/physiology
- Translocation, Genetic
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Affiliation(s)
- B Zeevaert
- Service d'Electroneuromyographie et de Médecine de l'Appareil Locomoteur, CHU Sart Tilman, Université de Liège, Belgique, France
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