1
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Zhang Z, Zhang X, Xue H, Chu L, Hu L, Bi X, Zhu P, Zhang D, Chen J, Cui X, Kong L, Liang B, Wu X. Preimplantation genetic testing as a means of preventing hereditary congenital myasthenic syndrome caused by RAPSN. Mol Genet Genomic Med 2024; 12:e2409. [PMID: 38511267 PMCID: PMC10955331 DOI: 10.1002/mgg3.2409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Revised: 01/30/2024] [Accepted: 02/13/2024] [Indexed: 03/22/2024] Open
Abstract
BACKGROUND Congenital myasthenic syndrome is a heterogeneous group of inherited neuromuscular transmission disorders. Variants in RAPSN are a common cause of CMS, accounting for approximately 14%-27% of all CMS cases. Whether preimplantation genetic testing for monogenic disease (PGT-M) could be used to prevent the potential birth of CMS-affected children is unclear. METHODS Application of WES (whole-exome sequencing) for carrier testing and guidance for the PGT-M in the absence of a genetically characterized index patient as well as assisted reproductive technology were employed to prevent the occurrence of birth defects in subsequent pregnancy. The clinical phenotypes of stillborn fetuses were also assessed. RESULTS The family carried two likely pathogenic variants in RAPSN(NM_005055.5): c.133G>A (p.V45M) and c.280G>A (p.E94K). And the potential birth of CMS-affected child was successfully prevented, allowing the family to have offspring devoid of disease-associated variants and exhibiting a normal phenotype. CONCLUSION This report constitutes the first documented case of achieving a CMS-free offspring through PGT-M in a CMS-affected family. By broadening the known variant spectrum of RAPSN in the Chinese population, our findings underscore the feasibility and effectiveness of PGT-M for preventing CMS, offering valuable insights for similarly affected families.
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Affiliation(s)
- Zhiping Zhang
- Center of Reproductive MedicineAffiliated Children's Hospital of Shanxi & Women Health Center of Shanxi Medicine UniversityTaiyuanShanxiChina
| | - Xueluo Zhang
- Center of Reproductive MedicineAffiliated Children's Hospital of Shanxi & Women Health Center of Shanxi Medicine UniversityTaiyuanShanxiChina
| | - Huiqin Xue
- Center of Reproductive MedicineAffiliated Children's Hospital of Shanxi & Women Health Center of Shanxi Medicine UniversityTaiyuanShanxiChina
| | - Liming Chu
- Basecare Medical Device Co., LtdSuzhouChina
| | - Lina Hu
- Basecare Medical Device Co., LtdSuzhouChina
| | - Xingyu Bi
- Center of Reproductive MedicineAffiliated Children's Hospital of Shanxi & Women Health Center of Shanxi Medicine UniversityTaiyuanShanxiChina
| | - Pengfei Zhu
- Center of Reproductive MedicineAffiliated Children's Hospital of Shanxi & Women Health Center of Shanxi Medicine UniversityTaiyuanShanxiChina
| | - Dongdong Zhang
- Center of Reproductive MedicineAffiliated Children's Hospital of Shanxi & Women Health Center of Shanxi Medicine UniversityTaiyuanShanxiChina
| | - Jiayao Chen
- Center of Reproductive MedicineAffiliated Children's Hospital of Shanxi & Women Health Center of Shanxi Medicine UniversityTaiyuanShanxiChina
| | - Xiangrong Cui
- Center of Reproductive MedicineAffiliated Children's Hospital of Shanxi & Women Health Center of Shanxi Medicine UniversityTaiyuanShanxiChina
| | | | - Bo Liang
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and BiotechnologyShanghai Jiao Tong UniversityShanghaiChina
| | - Xueqing Wu
- Center of Reproductive MedicineAffiliated Children's Hospital of Shanxi & Women Health Center of Shanxi Medicine UniversityTaiyuanShanxiChina
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2
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Bukhman YV, Morin PA, Meyer S, Chu LF, Jacobsen JK, Antosiewicz-Bourget J, Mamott D, Gonzales M, Argus C, Bolin J, Berres ME, Fedrigo O, Steill J, Swanson SA, Jiang P, Rhie A, Formenti G, Phillippy AM, Harris RS, Wood JMD, Howe K, Kirilenko BM, Munegowda C, Hiller M, Jain A, Kihara D, Johnston JS, Ionkov A, Raja K, Toh H, Lang A, Wolf M, Jarvis ED, Thomson JA, Chaisson MJP, Stewart R. A High-Quality Blue Whale Genome, Segmental Duplications, and Historical Demography. Mol Biol Evol 2024; 41:msae036. [PMID: 38376487 PMCID: PMC10919930 DOI: 10.1093/molbev/msae036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Revised: 01/11/2024] [Accepted: 01/22/2024] [Indexed: 02/21/2024] Open
Abstract
The blue whale, Balaenoptera musculus, is the largest animal known to have ever existed, making it an important case study in longevity and resistance to cancer. To further this and other blue whale-related research, we report a reference-quality, long-read-based genome assembly of this fascinating species. We assembled the genome from PacBio long reads and utilized Illumina/10×, optical maps, and Hi-C data for scaffolding, polishing, and manual curation. We also provided long read RNA-seq data to facilitate the annotation of the assembly by NCBI and Ensembl. Additionally, we annotated both haplotypes using TOGA and measured the genome size by flow cytometry. We then compared the blue whale genome with other cetaceans and artiodactyls, including vaquita (Phocoena sinus), the world's smallest cetacean, to investigate blue whale's unique biological traits. We found a dramatic amplification of several genes in the blue whale genome resulting from a recent burst in segmental duplications, though the possible connection between this amplification and giant body size requires further study. We also discovered sites in the insulin-like growth factor-1 gene correlated with body size in cetaceans. Finally, using our assembly to examine the heterozygosity and historical demography of Pacific and Atlantic blue whale populations, we found that the genomes of both populations are highly heterozygous and that their genetic isolation dates to the last interglacial period. Taken together, these results indicate how a high-quality, annotated blue whale genome will serve as an important resource for biology, evolution, and conservation research.
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Affiliation(s)
- Yury V Bukhman
- Regenerative Biology, Morgridge Institute for Research, Madison, WI 53715, USA
| | - Phillip A Morin
- Southwest Fisheries Science Center, National Oceanic and Atmospheric Administration (NOAA), La Jolla, CA 92037, USA
| | - Susanne Meyer
- Neuroscience Research Institute, University of California, Santa Barbara, CA, USA
| | - Li-Fang Chu
- Regenerative Biology, Morgridge Institute for Research, Madison, WI 53715, USA
- Department of Comparative Biology and Experimental Medicine, University of Calgary, Calgary, Canada
| | | | | | - Daniel Mamott
- Regenerative Biology, Morgridge Institute for Research, Madison, WI 53715, USA
| | - Maylie Gonzales
- Neuroscience Research Institute, University of California, Santa Barbara, CA, USA
| | - Cara Argus
- Regenerative Biology, Morgridge Institute for Research, Madison, WI 53715, USA
| | - Jennifer Bolin
- Regenerative Biology, Morgridge Institute for Research, Madison, WI 53715, USA
| | - Mark E Berres
- University of Wisconsin Biotechnology Center, Bioinformatics Resource Center, University of Wisconsin - Madison, Madison, WI 53706, USA
| | - Olivier Fedrigo
- Vertebrate Genome Lab, The Rockefeller University, New York, NY 10065, USA
| | - John Steill
- Regenerative Biology, Morgridge Institute for Research, Madison, WI 53715, USA
| | - Scott A Swanson
- Regenerative Biology, Morgridge Institute for Research, Madison, WI 53715, USA
| | - Peng Jiang
- Center for Gene Regulation in Health and Disease (GRHD), Cleveland State University, Cleveland, OH, USA
- Department of Biological, Geological and Environmental Sciences, Cleveland State University, Cleveland, OH, USA
- Center for RNA Science and Therapeutics, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Arang Rhie
- Genome Informatics Section, National Human Genome Research Institute, Bethesda, MD 20892, USA
| | - Giulio Formenti
- Laboratory of Neurogenetics of Language, The Rockefeller University/HHMI, New York, NY 10065, USA
| | - Adam M Phillippy
- Genome Informatics Section, National Human Genome Research Institute, Bethesda, MD 20892, USA
| | - Robert S Harris
- Department of Biology, Pennsylvania State University, University Park, PA 16802, USA
| | | | - Kerstin Howe
- Tree of Life, Wellcome Sanger Institute, Cambridge CB10 1SA, UK
| | - Bogdan M Kirilenko
- LOEWE Centre for Translational Biodiversity Genomics, 60325 Frankfurt, Germany
- Senckenberg Research Institute, 60325 Frankfurt, Germany
- Institute of Cell Biology and Neuroscience, Faculty of Biosciences, Goethe University Frankfurt, 60438 Frankfurt, Germany
| | - Chetan Munegowda
- LOEWE Centre for Translational Biodiversity Genomics, 60325 Frankfurt, Germany
- Senckenberg Research Institute, 60325 Frankfurt, Germany
- Institute of Cell Biology and Neuroscience, Faculty of Biosciences, Goethe University Frankfurt, 60438 Frankfurt, Germany
| | - Michael Hiller
- LOEWE Centre for Translational Biodiversity Genomics, 60325 Frankfurt, Germany
- Senckenberg Research Institute, 60325 Frankfurt, Germany
- Institute of Cell Biology and Neuroscience, Faculty of Biosciences, Goethe University Frankfurt, 60438 Frankfurt, Germany
| | - Aashish Jain
- Department of Computer Science, Purdue University, West Lafayette, IN 47907, USA
| | - Daisuke Kihara
- Department of Computer Science, Purdue University, West Lafayette, IN 47907, USA
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - J Spencer Johnston
- Department of Entomology, Texas A&M University, College Station, TX 77843, USA
| | - Alexander Ionkov
- Regenerative Biology, Morgridge Institute for Research, Madison, WI 53715, USA
| | - Kalpana Raja
- Regenerative Biology, Morgridge Institute for Research, Madison, WI 53715, USA
| | - Huishi Toh
- Neuroscience Research Institute, University of California, Santa Barbara, CA, USA
| | - Aimee Lang
- Southwest Fisheries Science Center, National Oceanic and Atmospheric Administration (NOAA), La Jolla, CA 92037, USA
| | - Magnus Wolf
- Institute for Evolution and Biodiversity (IEB), University of Muenster, 48149, Muenster, Germany
- Senckenberg Biodiversity and Climate Research Centre (BiK-F), Frankfurt am Main, Germany
| | - Erich D Jarvis
- Vertebrate Genome Lab, The Rockefeller University, New York, NY 10065, USA
- Laboratory of Neurogenetics of Language, The Rockefeller University/HHMI, New York, NY 10065, USA
| | - James A Thomson
- Regenerative Biology, Morgridge Institute for Research, Madison, WI 53715, USA
- Department of Molecular, Cellular and Developmental Biology, University of California Santa Barbara, Santa Barbara, CA 93106, USA
- Department of Cell and Regenerative Biology, University of Wisconsin School of Medicine and Public Health, Madison, WI 53726, USA
| | - Mark J P Chaisson
- Department of Quantitative and Computational Biology, University of Southern California, Los Angeles, Los Angeles, CA 90089, USA
| | - Ron Stewart
- Regenerative Biology, Morgridge Institute for Research, Madison, WI 53715, USA
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3
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Oury J, Zhang W, Leloup N, Koide A, Corrado AD, Ketavarapu G, Hattori T, Koide S, Burden SJ. Mechanism of disease and therapeutic rescue of Dok7 congenital myasthenia. Nature 2021; 595:404-408. [PMID: 34163073 PMCID: PMC8277574 DOI: 10.1038/s41586-021-03672-3] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Accepted: 05/25/2021] [Indexed: 11/09/2022]
Abstract
Congenital myasthenia (CM) is a devastating neuromuscular disease, and mutations in DOK7, an adaptor protein that is crucial for forming and maintaining neuromuscular synapses, are a major cause of CM1,2. The most common disease-causing mutation (DOK71124_1127 dup) truncates DOK7 and leads to the loss of two tyrosine residues that are phosphorylated and recruit CRK proteins, which are important for anchoring acetylcholine receptors at synapses. Here we describe a mouse model of this common form of CM (Dok7CM mice) and a mouse with point mutations in the two tyrosine residues (Dok72YF). We show that Dok7CM mice had severe deficits in neuromuscular synapse formation that caused neonatal lethality. Unexpectedly, these deficits were due to a severe deficiency in phosphorylation and activation of muscle-specific kinase (MUSK) rather than a deficiency in DOK7 tyrosine phosphorylation. We developed agonist antibodies against MUSK and show that these antibodies restored neuromuscular synapse formation and prevented neonatal lethality and late-onset disease in Dok7CM mice. These findings identify an unexpected cause for disease and a potential therapy for both DOK7 CM and other forms of CM caused by mutations in AGRIN, LRP4 or MUSK, and illustrate the potential of targeted therapy to rescue congenital lethality.
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Affiliation(s)
- Julien Oury
- Helen L. and Martin S. Kimmel Center for Biology and Medicine at the Skirball Institute of Biomolecular Medicine, NYU Grossman School of Medicine, New York, NY, USA
| | - Wei Zhang
- Helen L. and Martin S. Kimmel Center for Biology and Medicine at the Skirball Institute of Biomolecular Medicine, NYU Grossman School of Medicine, New York, NY, USA
| | - Nadia Leloup
- Perlmutter Cancer Center, NYU Langone Health, New York, NY, USA
| | - Akiko Koide
- Perlmutter Cancer Center, NYU Langone Health, New York, NY, USA.,Department of Medicine, NYU Grossman School of Medicine, New York, NY, USA
| | | | | | - Takamitsu Hattori
- Perlmutter Cancer Center, NYU Langone Health, New York, NY, USA.,Department of Biochemistry and Molecular Pharmacology, NYU Grossman School of Medicine, New York, NY, USA
| | - Shohei Koide
- Perlmutter Cancer Center, NYU Langone Health, New York, NY, USA. .,Department of Biochemistry and Molecular Pharmacology, NYU Grossman School of Medicine, New York, NY, USA.
| | - Steven J Burden
- Helen L. and Martin S. Kimmel Center for Biology and Medicine at the Skirball Institute of Biomolecular Medicine, NYU Grossman School of Medicine, New York, NY, USA.
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4
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An Inside Job: Molecular Determinants for Postsynaptic Localization of Nicotinic Acetylcholine Receptors. Molecules 2021; 26:molecules26113065. [PMID: 34063759 PMCID: PMC8196675 DOI: 10.3390/molecules26113065] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 05/13/2021] [Accepted: 05/15/2021] [Indexed: 11/29/2022] Open
Abstract
Nicotinic acetylcholine receptors (nAChRs) mediate fast synaptic transmission at neuromuscular and autonomic ganglionic synapses in the peripheral nervous system. The postsynaptic localization of muscle ((α1)2β1γδ) and neuronal ((α3β4)2β4) nicotinic receptors at these synapses is mediated by interactions between the nAChR intracellular domains and cytoplasmic scaffolding proteins. Recent high resolution structures and functional studies provide new insights into the molecular determinants that mediate these interactions. Surprisingly, they reveal that the muscle nAChR binds 1–3 rapsyn scaffolding molecules, which dimerize and thereby form an interconnected lattice between receptors. Moreover, rapsyn binds two distinct sites on the nAChR subunit cytoplasmic loops; the MA-helix on one or more subunits and a motif specific to the β subunit. Binding at the latter site is regulated by agrin-induced phosphorylation of βY390, and increases the stoichiometry of rapsyn/AChR complexes. Similarly, the neuronal nAChR may be localized at ganglionic synapses by phosphorylation-dependent interactions with 14-3-3 adaptor proteins which bind specific motifs in each of the α3 subunit cytoplasmic loops. Thus, postsynaptic localization of nAChRs is mediated by regulated interactions with multiple scaffolding molecules, and the stoichiometry of these complexes likely helps regulate the number, density, and stability of receptors at the synapse.
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5
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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] [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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6
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Wang A, Xiao Y, Huang P, Liu L, Xiong J, Li J, Mao D, Liu L. Novel NtA and LG1 Mutations in Agrin in a Single Patient Causes Congenital Myasthenic Syndrome. Front Neurol 2020; 11:239. [PMID: 32328026 PMCID: PMC7160337 DOI: 10.3389/fneur.2020.00239] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2019] [Accepted: 03/12/2020] [Indexed: 12/27/2022] Open
Abstract
Congenital myasthenic syndrome (CMS) is a group of genetic disorders of neuromuscular transmission that is characterized by muscle weakness. A mutation in the gene encoding agrin (AGRN) is a rare cause of CMS, and only a few families or isolated cases have been reported. We reported a pediatric proband exhibiting muscle weakness in the trunk and limbs with skeletal malformation and intellectual disability and performed whole-exome sequencing (WES) of the proband parent-offspring trio. Results revealed a new compound heterozygous mutation in AGRN: c.125A>C (p.Glu42Ala) in the N-terminal agrin domain (NtA) and c.4516G>A (p.Ala1506Thr) in the laminin G1 domain (LG1). Bioinformatic analysis predicted the mutation as possibly pathogenic. The new compound heterozygous mutation in AGRN may disrupt agrin's known function of bridging laminin and α-dystroglycan and undermine the formation and maintenance of the neuromuscular junction (NMJ) via both muscular and neural agrin pathways. It may also induce secondary peripheral neuropathy and skeletal malformation.
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Affiliation(s)
- Aiping Wang
- Department of Pediatrics, The Second Xiangya Hospital, Central South University, Changsha, China.,Department of Pediatrics Neurology, Children's Medical Center, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Yangyang Xiao
- Department of Pediatrics, The Second Xiangya Hospital, Central South University, Changsha, China.,Department of Pediatrics Neurology, Children's Medical Center, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Peng Huang
- Department of Pediatrics, The Second Xiangya Hospital, Central South University, Changsha, China.,Department of Pediatrics Neurology, Children's Medical Center, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Lingjuan Liu
- Department of Pediatrics, The Second Xiangya Hospital, Central South University, Changsha, China.,Department of Pediatrics Neurology, Children's Medical Center, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Jie Xiong
- Department of Pediatrics, The Second Xiangya Hospital, Central South University, Changsha, China.,Department of Pediatrics Neurology, Children's Medical Center, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Jian Li
- Department of Pediatrics, The Second Xiangya Hospital, Central South University, Changsha, China.,Department of Pediatrics Neurology, Children's Medical Center, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Ding'an Mao
- Department of Pediatrics, The Second Xiangya Hospital, Central South University, Changsha, China.,Department of Pediatrics Neurology, Children's Medical Center, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Liqun Liu
- Department of Pediatrics, The Second Xiangya Hospital, Central South University, Changsha, China.,Department of Pediatrics Neurology, Children's Medical Center, The Second Xiangya Hospital, Central South University, Changsha, China
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7
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Severe congenital myasthenic syndrome associated with novel biallelic mutation of the CHRND gene. Neuromuscul Disord 2020; 30:336-339. [DOI: 10.1016/j.nmd.2020.02.012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2019] [Revised: 01/14/2020] [Accepted: 02/16/2020] [Indexed: 11/20/2022]
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8
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A late-onset congenital myasthenic syndrome due to a heterozygous DOK7 mutation. Neuromuscul Disord 2020; 30:331-335. [DOI: 10.1016/j.nmd.2020.02.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 02/02/2020] [Accepted: 02/17/2020] [Indexed: 02/06/2023]
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9
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Rudell JB, Maselli RA, Yarov-Yarovoy V, Ferns MJ. Pathogenic effects of agrin V1727F mutation are isoform specific and decrease its expression and affinity for HSPGs and LRP4. Hum Mol Genet 2019; 28:2648-2658. [PMID: 30994901 PMCID: PMC6687949 DOI: 10.1093/hmg/ddz081] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Revised: 03/27/2019] [Accepted: 04/15/2019] [Indexed: 12/17/2022] Open
Abstract
Agrin is a large extracellular matrix protein whose isoforms differ in their tissue distribution and function. Motoneuron-derived y+z+ agrin regulates the formation of the neuromuscular junction (NMJ), while y-z- agrin is widely expressed and has diverse functions. Previously we identified a missense mutation (V1727F) in the second laminin globular (LG2) domain of agrin that causes severe congenital myasthenic syndrome. Here, we define pathogenic effects of the agrin V1727F mutation that account for the profound dysfunction of the NMJ. First, by expressing agrin variants in heterologous cells, we show that the V1727F mutation reduces the secretion of y+z+ agrin compared to wild type, whereas it has no effect on the secretion of y-z- agrin. Second, we find that the V1727F mutation significantly impairs binding of y+z+ agrin to both heparin and the low-density lipoprotein receptor-related protein 4 (LRP4) coreceptor. Third, molecular modeling of the LG2 domain suggests that the V1727F mutation primarily disrupts the y splice insert, and consistent with this we find that it partially occludes the contribution of the y splice insert to agrin binding to heparin and LRP4. Together, these findings identify several pathogenic effects of the V1727F mutation that reduce its expression and ability to bind heparan sulfate proteoglycan and LRP4 coreceptors involved in the muscle-specific kinase signaling pathway. These defects primarily impair the function of neural y+z+ agrin and combine to cause a severe CMS phenotype, whereas y-z- agrin function in other tissues appears preserved.
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Affiliation(s)
- John B Rudell
- Department of Physiology and Membrane Biology, University of California Davis, Davis, CA, USA
| | - Ricardo A Maselli
- Department of Neurology, University of California Davis, Davis, CA, USA
| | - Vladimir Yarov-Yarovoy
- Department of Physiology and Membrane Biology, University of California Davis, Davis, CA, USA
| | - Michael J Ferns
- Department of Physiology and Membrane Biology, University of California Davis, Davis, CA, USA
- Department of Anesthesiology and Pain Medicine, University of California Davis, Davis, CA, USA
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10
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Koppel N, Friese MB, Cardasis HL, Neubert TA, Burden SJ. Vezatin is required for the maturation of the neuromuscular synapse. Mol Biol Cell 2019; 30:2571-2583. [PMID: 31411944 PMCID: PMC6740198 DOI: 10.1091/mbc.e19-06-0313] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Key genes, such as Agrin, Lrp4, and MuSK, are required for the initial formation, subsequent maturation, and long-term stabilization of mammalian neuromuscular synapses. Additional molecules are thought to function selectively during the evolution and stabilization of these synapses, but these molecular players are largely unknown. Here, we used mass spectrometry to identify vezatin, a two-pass transmembrane protein, as an acetylcholine receptor (AChR)–associated protein, and we provide evidence that vezatin binds directly to AChRs. We show that vezatin is dispensable for the formation of synapses but plays a later role in the emergence of a topologically complex and branched shape of the synapse, as well as the stabilization of AChRs. In addition, neuromuscular synapses in vezatin mutant mice display premature signs of deterioration, normally found only during aging. Thus, vezatin has a selective role in the structural elaboration and postnatal maturation of murine neuromuscular synapses.
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Affiliation(s)
- Natasha Koppel
- Helen L. and Martin S. Kimmel Center for Biology and Medicine, Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY 10016
| | - Matthew B Friese
- Helen L. and Martin S. Kimmel Center for Biology and Medicine, Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY 10016
| | - Helene L Cardasis
- Helen L. and Martin S. Kimmel Center for Biology and Medicine, Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY 10016
| | - Thomas A Neubert
- Helen L. and Martin S. Kimmel Center for Biology and Medicine, Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY 10016
| | - Steven J Burden
- Helen L. and Martin S. Kimmel Center for Biology and Medicine, Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY 10016
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11
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Oury J, Liu Y, Töpf A, Todorovic S, Hoedt E, Preethish-Kumar V, Neubert TA, Lin W, Lochmüller H, Burden SJ. MACF1 links Rapsyn to microtubule- and actin-binding proteins to maintain neuromuscular synapses. J Cell Biol 2019; 218:1686-1705. [PMID: 30842214 PMCID: PMC6504910 DOI: 10.1083/jcb.201810023] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Revised: 01/07/2019] [Accepted: 02/07/2019] [Indexed: 12/20/2022] Open
Abstract
Oury et al. show that the scaffolding protein MACF1 links Rapsyn, which binds acetylcholine receptors, to the microtubule- and actin-network at neuromuscular synapses. MACF1 thereby plays a role in synaptic maturation in mice, and mutations of MACF1 are associated with congenital myasthenia in humans. Complex mechanisms are required to form neuromuscular synapses, direct their subsequent maturation, and maintain the synapse throughout life. Transcriptional and post-translational pathways play important roles in synaptic differentiation and direct the accumulation of the neurotransmitter receptors, acetylcholine receptors (AChRs), to the postsynaptic membrane, ensuring for reliable synaptic transmission. Rapsyn, an intracellular peripheral membrane protein that binds AChRs, is essential for synaptic differentiation, but how Rapsyn acts is poorly understood. We screened for proteins that coisolate with AChRs in a Rapsyn-dependent manner and show that microtubule actin cross linking factor 1 (MACF1), a scaffolding protein with binding sites for microtubules (MT) and actin, is concentrated at neuromuscular synapses, where it binds Rapsyn and serves as a synaptic organizer for MT-associated proteins, EB1 and MAP1b, and the actin-associated protein, Vinculin. MACF1 plays an important role in maintaining synaptic differentiation and efficient synaptic transmission in mice, and variants in MACF1 are associated with congenital myasthenia in humans.
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Affiliation(s)
- Julien Oury
- Helen L. and Martin S. Kimmel Center for Biology and Medicine at the Skirball Institute of Biomolecular Medicine, New York University Medical School, New York, NY
| | - Yun Liu
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX
| | - Ana Töpf
- John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
| | - Slobodanka Todorovic
- Clinic for Neurology and Psychiatry for Children and Youth, Belgrade, Serbia and Faculty of Medicine, University of Belgrade, Belgrade, Serbia
| | - Esthelle Hoedt
- Helen L. and Martin S. Kimmel Center for Biology and Medicine at the Skirball Institute of Biomolecular Medicine, New York University Medical School, New York, NY
| | | | - Thomas A Neubert
- Helen L. and Martin S. Kimmel Center for Biology and Medicine at the Skirball Institute of Biomolecular Medicine, New York University Medical School, New York, NY
| | - Weichun Lin
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX
| | - Hanns Lochmüller
- Department of Neuropediatrics and Muscle Disorders, Medical Center, University of Freiburg, Faculty of Medicine, Freiburg, Germany.,Centro Nacional de Análisis Genómico, Center for Genomic Regulation, Barcelona Institute of Science and Technology, Barcelona, Spain.,Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, Canada.,Division of Neurology, Department of Medicine, The Ottawa Hospital, Ottawa, Canada
| | - Steven J Burden
- Helen L. and Martin S. Kimmel Center for Biology and Medicine at the Skirball Institute of Biomolecular Medicine, New York University Medical School, New York, NY
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12
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McMacken G, Cox D, Roos A, Müller J, Whittaker R, Lochmüller H. The beta-adrenergic agonist salbutamol modulates neuromuscular junction formation in zebrafish models of human myasthenic syndromes. Hum Mol Genet 2019; 27:1556-1564. [PMID: 29462491 PMCID: PMC5905648 DOI: 10.1093/hmg/ddy062] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2017] [Accepted: 02/14/2018] [Indexed: 11/15/2022] Open
Abstract
Inherited defects of the neuromuscular junction (NMJ) comprise an increasingly diverse range of disorders, termed congenital myasthenic syndromes (CMS). Therapies acting on the sympathetic nervous system, including the selective β2 adrenergic agonist salbutamol and the α and β adrenergic agonist ephedrine, have become standard treatment for several types of CMS. However, the mechanism of the therapeutic effect of sympathomimetics in these disorders is not understood. Here, we examined the effect of salbutamol on NMJ development using zebrafish with deficiency of the key postsynaptic proteins Dok-7 and MuSK. Treatment with salbutamol reduced motility defects in zebrafish embryos and larvae. In addition, salbutamol lead to morphological improvement of postsynaptic acetycholine receptor (AChR) clustering and size of synaptic contacts in Dok-7-deficient zebrafish. In MuSK-deficient zebrafish, salbutamol treatment reduced motor axon pathfinding defects and partially restored the formation of aneural prepatterned AChRs. In addition, the effects of salbutamol treatment were prevented by pre-treatment with a selective β2 antagonist. Treatment with the cyclic adenosine monophosphate (cAMP) activator forskolin, replicated the effects of salbutamol treatment. These results suggest that sympathomimetics exert a direct effect on neuromuscular synaptogenesis and do so via β2 adrenoceptors and via a cAMP-dependent pathway.
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Affiliation(s)
- Grace McMacken
- Institute of Genetic Medicine, The John Walton Muscular Dystrophy Research Centre, Newcastle University, International Centre for Life, Newcastle Upon Tyne NE1 3BZ, UK
| | - Dan Cox
- Institute of Genetic Medicine, The John Walton Muscular Dystrophy Research Centre, Newcastle University, International Centre for Life, Newcastle Upon Tyne NE1 3BZ, UK
| | - Andreas Roos
- Institute of Genetic Medicine, The John Walton Muscular Dystrophy Research Centre, Newcastle University, International Centre for Life, Newcastle Upon Tyne NE1 3BZ, UK.,Tissue Omics Project Group, Biomedical Research Department, Leibniz-Institut für Analytische Wissenschaften-ISAS-e.V., 44227 Dortmund, Germany
| | - Juliane Müller
- Institute of Genetic Medicine, Wellcome Trust Centre for Mitochondrial Research, Newcastle University, International Centre for Life, Newcastle Upon Tyne NE1 3BZ, UK
| | - Roger Whittaker
- Institute of Neuroscience, Newcastle University, Newcastle Upon Tyne NE1 7RU, UK
| | - Hanns Lochmüller
- Institute of Genetic Medicine, The John Walton Muscular Dystrophy Research Centre, Newcastle University, International Centre for Life, Newcastle Upon Tyne NE1 3BZ, UK
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13
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[Congenital myasthenic syndromes in adulthood : Challenging, rare but treatable]. DER NERVENARZT 2018; 90:148-159. [PMID: 29974128 DOI: 10.1007/s00115-018-0562-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
The congenital myasthenic syndromes (CMS) represent a heterogeneous group of diseases with a broad spectrum of phenotypes. The common characteristic is an inherited genetic defect of the neuromuscular junction. Although in some patients the specific gene defect remains to be detected, the increasing identification of causative genes in recent years has already provided unique insights into the functionality of structural proteins at the neuromuscular junction. Neonatal and early childhood onset is observed in most CMS subtypes; however, late onset in adolescence or adulthood also occurs and establishing the diagnosis at these stages imposes particular challenges. To enable appropriate therapeutic interventions for an at least in principle treatable condition, determining the genetic cause is warranted. In this overview, the critical clinical and diagnostic features of the different CMS subtypes are presented and illustrated using typical cases. Furthermore, specific diagnostic clues are outlined. Finally, the overlap between CMS and muscular dystrophies is discussed. Illustrating characteristic patient examples, the essential clinical and additional diagnostic findings of various CMS subtypes and special diagnostic indications are presented.
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14
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Durmus H, Shen XM, Serdaroglu-Oflazer P, Kara B, Parman-Gulsen Y, Ozdemir C, Brengman J, Deymeer F, Engel AG. Congenital myasthenic syndromes in Turkey: Clinical clues and prognosis with long term follow-up. Neuromuscul Disord 2018; 28:315-322. [PMID: 29395675 PMCID: PMC5924610 DOI: 10.1016/j.nmd.2017.11.013] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Revised: 11/07/2017] [Accepted: 11/20/2017] [Indexed: 11/28/2022]
Abstract
Congenital myasthenic syndromes (CMS) are a group of hereditary disorders affecting the neuromuscular junction. Here, we present clinical, electrophysiological and genetic findings of 69 patients from 51 unrelated kinships from Turkey. Genetic tests of 60 patients were performed at Mayo Clinic. Median follow-up time was 9.8 years (range 1-22 years). The most common CMS was primary acetylcholine receptor (AChR) deficiency (31/51) and the most common mutations in AChR were c.1219 + 2T > G (12/51) and c.1327delG (6/51) in CHRNE. Four of our 5 kinships with AChE deficiency carried p.W148X that truncates the collagen domain of COLQ, and was previously reported only in patients from Turkey. These were followed by GFPT1 deficiency (4/51), DOK7 deficiency (3/51), slow channel CMS (3/51), fast channel CMS (3/51), choline acetyltransferase deficiency (1/51) and a CMS associated with desmin deficiency (1/51). Distribution of muscle weakness was sometimes useful in giving a clue to the CMS subtype. Presence of repetitive compound muscle action potentials pointed to AChE deficiency or slow channel CMS. Our experience confirms that one needs to be cautious using pyridostigmine, since it can worsen some types of CMS. Ephedrine/salbutamol were very effective in AChE and DOK7 deficiencies and were useful as adjuncts in other types of CMS. Long follow-up gave us a chance to assess progression of the disease, and to witness 12 mainly uneventful pregnancies in 8 patients. In this study, we describe some new phenotypes and detail the clinical features of the well-known CMS.
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Affiliation(s)
- Hacer Durmus
- Department of Neurology, Istanbul Medical Faculty, Istanbul University, Capa, 34390, Istanbul, Turkey
| | - Xin-Ming Shen
- Department of Neurology, Mayo Clinic, Rochester, MN, USA
| | - Piraye Serdaroglu-Oflazer
- Department of Neurology, Istanbul Medical Faculty, Istanbul University, Capa, 34390, Istanbul, Turkey
| | - Bulent Kara
- Department of Neurology, Istanbul Medical Faculty, Istanbul University, Capa, 34390, Istanbul, Turkey
| | - Yesim Parman-Gulsen
- Department of Neurology, Istanbul Medical Faculty, Istanbul University, Capa, 34390, Istanbul, Turkey
| | - Coskun Ozdemir
- Department of Neurology, Istanbul Medical Faculty, Istanbul University, Capa, 34390, Istanbul, Turkey
| | - Joan Brengman
- Department of Neurology, Mayo Clinic, Rochester, MN, USA
| | - Feza Deymeer
- Department of Neurology, Istanbul Medical Faculty, Istanbul University, Capa, 34390, Istanbul, Turkey.
| | - Andrew G Engel
- Department of Neurology, Mayo Clinic, Rochester, MN, USA
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15
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Sigoillot SM, Bourgeois F, Karmouch J, Molgó J, Dobbertin A, Chevalier C, Houlgatte R, Léger J, Legay C. Neuromuscular junction immaturity and muscle atrophy are hallmarks of the ColQ-deficient mouse, a model of congenital myasthenic syndrome with acetylcholinesterase deficiency. FASEB J 2016; 30:2382-99. [PMID: 26993635 DOI: 10.1096/fj.201500162] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Accepted: 02/26/2016] [Indexed: 12/13/2022]
Abstract
The collagen ColQ anchors acetylcholinesterase (AChE) in the synaptic cleft of the neuromuscular junction (NMJ). It also binds MuSK and perlecan/dystroglycan, 2 signaling platforms of the postsynaptic domain. Mutations in ColQ cause a congenital myasthenic syndrome (CMS) with AChE deficiency. Because the absence of AChE does not fully explain the complexity of the syndrome and there is no curative treatment for the disease, we explored additional potential targets of ColQ by conducting a large genetic screening of ColQ-deficient mice, a model for CMS with AChE deficiency, and analyzed their NMJ and muscle phenotypes. We demonstrated that ColQ controls the development and the maturation of the postsynaptic domain by regulating synaptic gene expression. Notably, ColQ deficiency leads to an up-regulation of the 5 subunits of the nicotinic acetylcholine receptor (AChR), leading to mixed mature and immature AChRs at the NMJ of adult mice. ColQ also regulates the expression of extracellular matrix (ECM) components. However, whereas the ECM mRNAs were down-regulated in vitro, compensation seemed to occur in vivo to maintain normal levels of these mRNAs. Finally, ColQ deficiency leads to a general atrophic phenotype and hypoplasia that affect fast muscles. This study points to new specific hallmarks for this CMS.-Sigoillot, S. M., Bourgeois, F., Karmouch, J., Molgó, J., Dobbertin, A., Chevalier, C., Houlgatte, R., Léger, J., Legay, C. Neuromuscular junction immaturity and muscle atrophy are hallmarks of the ColQ-deficient mouse, a model of congenital myasthenic syndrome with acetylcholinesterase deficiency.
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Affiliation(s)
- Séverine M Sigoillot
- Centre de Neurophysique, Physiologie et Pathologie, Centre National de la Recherche Scientifique (CNRS), Unité Mixte de Recherche (UMR) 8119, Université Paris Descartes, Sorbonne Paris Cité, Paris France
| | - Francine Bourgeois
- Centre de Neurophysique, Physiologie et Pathologie, Centre National de la Recherche Scientifique (CNRS), Unité Mixte de Recherche (UMR) 8119, Université Paris Descartes, Sorbonne Paris Cité, Paris France
| | - Jennifer Karmouch
- Centre de Neurophysique, Physiologie et Pathologie, Centre National de la Recherche Scientifique (CNRS), Unité Mixte de Recherche (UMR) 8119, Université Paris Descartes, Sorbonne Paris Cité, Paris France
| | - Jordi Molgó
- Commissariat à l'énergie Atomique et aux Energies Alternatives, Institut de Biologie et Technologies de Saclay, Service d'Ingénierie Moléculaire des Protéines, Gif sur Yvette, France; Institut des Neurosciences Paris-Saclay, UMR 9197, CNRS/Université Paris-Sud, Paris, France; and
| | - Alexandre Dobbertin
- Centre de Neurophysique, Physiologie et Pathologie, Centre National de la Recherche Scientifique (CNRS), Unité Mixte de Recherche (UMR) 8119, Université Paris Descartes, Sorbonne Paris Cité, Paris France
| | - Catherine Chevalier
- Institut de Recherche Thérapeutique de l'Université de Nantes, Plateforme Génomique Intégrative, Nantes, France
| | - Rémi Houlgatte
- Institut de Recherche Thérapeutique de l'Université de Nantes, Plateforme Génomique Intégrative, Nantes, France
| | - Jean Léger
- Institut de Recherche Thérapeutique de l'Université de Nantes, Plateforme Génomique Intégrative, Nantes, France
| | - Claire Legay
- Centre de Neurophysique, Physiologie et Pathologie, Centre National de la Recherche Scientifique (CNRS), Unité Mixte de Recherche (UMR) 8119, Université Paris Descartes, Sorbonne Paris Cité, Paris France;
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16
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Assessment of the functionality and stability of detergent purified nAChR from Torpedo using lipidic matrixes and macroscopic electrophysiology. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1858:47-56. [PMID: 26454038 DOI: 10.1016/j.bbamem.2015.10.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Revised: 09/17/2015] [Accepted: 10/01/2015] [Indexed: 11/21/2022]
Abstract
In our previous study we examined the functionality and stability of nicotinic acetylcholine receptor (nAChR)-detergent complexes (nAChR-DCs) from affinity-purified Torpedo californica (Tc) using fluorescence recovery after photobleaching (FRAP) in Lipidic Cubic Phase (LCP) and planar lipid bilayer (PLB) recordings for phospholipid and cholesterol like detergents. In the present study we enhanced the functional characterization of nAChR-DCs by recording macroscopic ion channel currents in Xenopus oocytes using the two electrode voltage clamp (TEVC). The use of TEVC allows for the recording of macroscopic currents elicited by agonist activation of nAChR-DCs that assemble in the oocyte plasma membrane. Furthermore, we examined the stability of nAChR-DCs, which is obligatory for the nAChR crystallization, using a 30 day FRAP assay in LCP for each detergent. The present results indicate a marked difference in the fractional fluorescence recovery (ΔFFR) within the same detergent family during the 30 day period assayed. Within the cholesterol analog family, sodium cholate and CHAPSO displayed a minimum ΔFFR and a mobile fraction (MF) over 80%. In contrast, CHAPS and BigCHAP showed a marked decay in both the mobile fraction and diffusion coefficient. nAChR-DCs containing phospholipid analog detergents with an alkylphosphocholine (FC) and lysofoscholine (LFC) of 16 carbon chains (FC-16, LFC-16) were more effective in maintaining a mobile fraction of over 80% compared to their counterparts with shorter acyl chain (C12, C14). The significant differences in macroscopic current amplitudes, activation and desensitization rates among the different nAChR-DCs evaluated in the present study allow to dissect which detergent preserves both, agonist activation and ion channel function. Functionality assays using TEVC demonstrated that LFC16, LFC14, and cholate were the most effective detergents in preserving macroscopic ion channel function, however, the nAChR-cholate complex display a significant delay in the ACh-induce channel activation. In summary, these results suggest that the physical properties of the lipid analog detergents (headgroup and acyl chain length) are the most effective in maintaining both the stability and functionality of the nAChR in the detergent solubilized complex.
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Zoltowska Katarzyna M, Belaya K, Leite M, Patrick W, Vincent A, Beeson D. Collagen Q--a potential target for autoantibodies in myasthenia gravis. J Neurol Sci 2014; 348:241-4. [PMID: 25577314 DOI: 10.1016/j.jns.2014.12.015] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2014] [Revised: 12/08/2014] [Accepted: 12/11/2014] [Indexed: 01/11/2023]
Abstract
Myasthenia gravis (MG) is an autoimmune disorder caused by autoantibodies targeting proteins expressed at the neuromuscular junction (NMJ). In most cases the targets are acetylcholine receptor (AChR), muscle-specific tyrosine kinase (MuSK), or occasionally low-density lipoprotein receptor-related protein 4 (LRP4), but there is still a group of patients, often called seronegative MG (SNMG), with unknown antibody targets. One potential target is collagen Q (COLQ), which is restricted to the NMJ and is crucial for anchoring the NMJ-specific form of acetylcholinesterase (AChE). 415 serum samples with a clinical diagnosis of MG and 43 control samples were screened for the presence of COLQ autoantibodies using a cell-based assay (CBA) with HEK293 cells overexpressing COLQ at the cell surface. COLQ antibodies were detected in 12/415 MG sera and in one/43 control samples. Five of the COLQ-Ab+individuals were also positive for AChR-Abs and 2 for MuSK-Abs. Although the COLQ antibodies were only present at low frequency, and did not differ significantly from the small control cohort, further studies could address whether they modify the clinical presentation or the benefits of anti-cholinesterase therapy.
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Affiliation(s)
- Marta Zoltowska Katarzyna
- Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Weatherall Institute of Molecular Medicine, Neurosciences Group, OX3 9DS, Oxford, UK
| | - Katsiaryna Belaya
- Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Weatherall Institute of Molecular Medicine, Neurosciences Group, OX3 9DS, Oxford, UK
| | - Maria Leite
- Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Weatherall Institute of Molecular Medicine, Neurosciences Group, OX3 9DS, Oxford, UK
| | - Waters Patrick
- Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Weatherall Institute of Molecular Medicine, Neurosciences Group, OX3 9DS, Oxford, UK
| | - Angela Vincent
- Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Weatherall Institute of Molecular Medicine, Neurosciences Group, OX3 9DS, Oxford, UK
| | - David Beeson
- Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Weatherall Institute of Molecular Medicine, Neurosciences Group, OX3 9DS, Oxford, UK.
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18
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McElnea EM, Stephenson K, Lanigan B, Flitcroft I. An ocular motility conundrum. BMJ Case Rep 2014; 2014:bcr-2014-206862. [PMID: 25349186 DOI: 10.1136/bcr-2014-206862] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Two siblings, an 11-year-old boy and a 7-year-old girl presented with bilateral symmetrical ptosis and limited eye movements. Having already been reviewed on a number of occasions by a variety of specialists in multiple hospital settings a diagnosis of their ocular motility disorder had remained elusive. We describe their cases, outline the differential diagnosis and review the investigations performed which were influential in finally making a diagnosis.
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Affiliation(s)
| | - Kirk Stephenson
- Department of Ophthalmology, Temple Street Children's University Hospital, Dublin 1, Ireland
| | - Bernie Lanigan
- Department of Ophthalmology, Temple Street Children's University Hospital, Dublin 1, Ireland
| | - Ian Flitcroft
- Department of Ophthalmology, Temple Street Children's University Hospital, Dublin 1, Ireland
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19
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Rudolf R, Bogomolovas J, Strack S, Choi KR, Khan MM, Wagner A, Brohm K, Hanashima A, Gasch A, Labeit D, Labeit S. Regulation of nicotinic acetylcholine receptor turnover by MuRF1 connects muscle activity to endo/lysosomal and atrophy pathways. AGE (DORDRECHT, NETHERLANDS) 2013; 35:1663-1674. [PMID: 22956146 PMCID: PMC3776120 DOI: 10.1007/s11357-012-9468-9] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/23/2012] [Accepted: 08/20/2012] [Indexed: 06/01/2023]
Abstract
Muscle atrophy is a process of muscle wasting induced under a series of catabolic stress conditions, such as denervation, disuse, cancer cachexia, heart and renal failure, AIDS, and aging. Neuromuscular junctions (NMJs), the synapses between motor neurons and muscle fibers undergo major changes in atrophying muscles, ranging from mild morphological alterations to complete disintegration. In this study, we hypothesized that remodeling of NMJs and muscle atrophy could be linked together. To test this, we examined if a major atrophy-promoting E3 ubiquitin ligase, MuRF1, is involved in the maintenance of NMJs. Immunofluorescence revealed that MuRF1 is highly enriched close to the NMJ. Affinity precipitation and in vivo imaging showed that MuRF1 interacts in endocytic structures with both, acetylcholine receptor, the primary postsynaptic protein of the NMJ, as well as with Bif-1, an autophagy- and endocytosis-regulating factor. In vivo imaging, radio labeling, and weighing approaches demonstrated that metabolic destabilization of acetylcholine receptors and muscle atrophy induced by denervation were significantly rescued in MuRF1-KO animals. Notably, interaction with Bif-1, and the rescue of AChR lifetime and muscle atrophy were specific to MuRF1 but not MuRF2. Our data demonstrate an involvement of MuRF1 in membrane protein-turnover, including the degradation of AChRs at the NMJ under atrophying conditions where MuRF1 also interacts and associates with Bif-1.
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Affiliation(s)
- Rüdiger Rudolf
- Institute of Toxicology and Genetics, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
- Institute of Molecular and Cell Biology, University of Applied Sciences Mannheim, Windeckstrasse 110, 68163 Mannheim, Germany
- Institute of Medical Technology, University of Heidelberg and University of Applied Sciences Mannheim, Paul-Wittsack-Strasse 10, 68163 Mannheim, Germany
| | - Julius Bogomolovas
- Department for Integrative Pathophysiology, Universitätsmedizin Mannheim, Theodor-Kutzer-Ufer, 68167 Mannheim, Germany
| | - Siegfried Strack
- Institute of Toxicology and Genetics, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Kyeong-Rok Choi
- Institute of Toxicology and Genetics, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Muzamil Majid Khan
- Institute of Toxicology and Genetics, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Anika Wagner
- Institute of Toxicology and Genetics, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Kathrin Brohm
- Department for Integrative Pathophysiology, Universitätsmedizin Mannheim, Theodor-Kutzer-Ufer, 68167 Mannheim, Germany
| | - Akira Hanashima
- Department for Integrative Pathophysiology, Universitätsmedizin Mannheim, Theodor-Kutzer-Ufer, 68167 Mannheim, Germany
| | - Alexander Gasch
- Department for Integrative Pathophysiology, Universitätsmedizin Mannheim, Theodor-Kutzer-Ufer, 68167 Mannheim, Germany
| | - Dittmar Labeit
- Department for Integrative Pathophysiology, Universitätsmedizin Mannheim, Theodor-Kutzer-Ufer, 68167 Mannheim, Germany
| | - Siegfried Labeit
- Department for Integrative Pathophysiology, Universitätsmedizin Mannheim, Theodor-Kutzer-Ufer, 68167 Mannheim, Germany
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20
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Barwick KES, Wright J, Al-Turki S, McEntagart MM, Nair A, Chioza B, Al-Memar A, Modarres H, Reilly MM, Dick KJ, Ruggiero AM, Blakely RD, Hurles ME, Crosby AH. Defective presynaptic choline transport underlies hereditary motor neuropathy. Am J Hum Genet 2012; 91:1103-7. [PMID: 23141292 DOI: 10.1016/j.ajhg.2012.09.019] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2012] [Revised: 07/16/2012] [Accepted: 09/20/2012] [Indexed: 11/18/2022] Open
Abstract
The neuromuscular junction (NMJ) is a specialized synapse with a complex molecular architecture that provides for reliable transmission between the nerve terminal and muscle fiber. Using linkage analysis and whole-exome sequencing of DNA samples from subjects with distal hereditary motor neuropathy type VII, we identified a mutation in SLC5A7, which encodes the presynaptic choline transporter (CHT), a critical determinant of synaptic acetylcholine synthesis and release at the NMJ. This dominantly segregating SLC5A7 mutation truncates the encoded product just beyond the final transmembrane domain, eliminating cytosolic-C-terminus sequences known to regulate surface transporter trafficking. Choline-transport assays in both transfected cells and monocytes from affected individuals revealed significant reductions in hemicholinium-3-sensitive choline uptake, a finding consistent with a dominant-negative mode of action. The discovery of CHT dysfunction underlying motor neuropathy identifies a biological basis for this group of conditions and widens the spectrum of disorders that derive from impaired NMJ transmission. Our findings compel consideration of mutations in SLC5A7 or its functional partners in relation to unexplained motor neuronopathies.
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Affiliation(s)
- Katy E S Barwick
- Centre for Human Genetics, St. George's University of London, Cranmer Terrace, London SW17 0RE, UK
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21
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Abicht A, Dusl M, Gallenmüller C, Guergueltcheva V, Schara U, Della Marina A, Wibbeler E, Almaras S, Mihaylova V, von der Hagen M, Huebner A, Chaouch A, Müller JS, Lochmüller H. Congenital myasthenic syndromes: Achievements and limitations of phenotype-guided gene-after-gene sequencing in diagnostic practice: A study of 680 patients. Hum Mutat 2012; 33:1474-84. [DOI: 10.1002/humu.22130] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2011] [Accepted: 04/30/2012] [Indexed: 11/09/2022]
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22
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Chaouch A, Beeson D, Hantaï D, Lochmüller H. 186th ENMC International Workshop: Congenital myasthenic syndromes 24–26 June 2011, Naarden, The Netherlands. Neuromuscul Disord 2012; 22:566-76. [DOI: 10.1016/j.nmd.2011.12.004] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2011] [Accepted: 12/13/2011] [Indexed: 12/24/2022]
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23
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Long-term follow-up of patients with congenital myasthenic syndrome caused by COLQ mutations. Neuromuscul Disord 2012; 22:318-24. [DOI: 10.1016/j.nmd.2011.09.002] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2011] [Revised: 08/24/2011] [Accepted: 09/02/2011] [Indexed: 11/18/2022]
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24
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Lorenzoni PJ, Scola RH, Kay CSK, Werneck LC. Congenital myasthenic syndrome: a brief review. Pediatr Neurol 2012; 46:141-8. [PMID: 22353287 DOI: 10.1016/j.pediatrneurol.2011.12.001] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2011] [Accepted: 12/22/2011] [Indexed: 01/04/2023]
Abstract
Congenital myasthenic syndromes comprise heterogeneous genetic diseases characterized by compromised neuromuscular transmission. Congenital myasthenic syndromes are classified as presynaptic, synaptic, or postsynaptic, depending on the primary defect's location within the neuromuscular junction. Presynaptic forms are the rarest, affecting an estimated 7-8% of patients; synaptic forms account for approximately 14-15% of patients; and the remaining 75-80% are attributable to postsynaptic defects. Clinical manifestations vary by congenital myasthenic syndrome subtype. Electrophysiologic, morphologic, and molecular descriptions of various forms of congenital myasthenic syndromes have led to an enhanced understanding of clinical manifestations and disease pathophysiology. Although congenital myasthenic syndromes are indicated by clinical manifestations, family history, electrophysiologic studies, and responses to acetylcholinesterase inhibitors, overlap in some presentations occurs. Therefore, genetic testing may be necessary to identify specific mutations in CHAT, COLQ, LAMB2, CHRNA, CHRNB, CHRND, CHRNE, CHRNG, RAPSN, DOK7, MUSK, AGRN, SCN4A, GFPT1, or PLEC1 genes. The identification of congenital myasthenic syndromes subtypes will prove important in the treatment of these patients. Different drugs may be beneficial, or should be avoided because they are ineffective or worsen some forms of congenital myasthenic syndromes. We explore the classification, clinical manifestations, electrophysiologic features, genetics, and treatment responses of each congenital myasthenic syndrome subtype.
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Affiliation(s)
- Paulo José Lorenzoni
- Neuromuscular Disorders Unit, Division of Neurology, Department of Internal Medicine, Hospital de Clínicas da Universidade Federal do Paraná, Curitiba, PR, Brazil
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25
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Choi KR, Berrera M, Reischl M, Strack S, Albrizio M, Röder IV, Wagner A, Petersen Y, Hafner M, Zaccolo M, Rudolf R. Rapsyn mediates subsynaptic anchoring of PKA type I and stabilisation of acetylcholine receptor in vivo. J Cell Sci 2012; 125:714-23. [PMID: 22331361 DOI: 10.1242/jcs.092361] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The stabilisation of acetylcholine receptors (AChRs) at the neuromuscular junction depends on muscle activity and the cooperative action of myosin Va and protein kinase A (PKA) type I. To execute its function, PKA has to be present in a subsynaptic microdomain where it is enriched by anchoring proteins. Here, we show that the AChR-associated protein, rapsyn, interacts with PKA type I in C2C12 and T-REx293 cells as well as in live mouse muscle beneath the neuromuscular junction. Molecular modelling, immunoprecipitation and bimolecular fluorescence complementation approaches identify an α-helical stretch of rapsyn to be crucial for binding to the dimerisation and docking domain of PKA type I. When expressed in live mouse muscle, a peptide encompassing the rapsyn α-helical sequence efficiently delocalises PKA type I from the neuromuscular junction. The same peptide, as well as a rapsyn construct lacking the α-helical domain, induces severe alteration of acetylcholine receptor turnover as well as fragmentation of synapses. This shows that rapsyn anchors PKA type I in close proximity to the postsynaptic membrane and suggests that this function is essential for synapse maintenance.
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Affiliation(s)
- Kyeong-Rok Choi
- Institut für Toxikologie und Genetik, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344, Eggenstein-Leopoldshafen, Germany
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26
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Leshinsky-Silver E, Shapira D, Yosovitz K, Ginsberg M, Lerman-Sagie T, Lev D. A novel mutation in the TPR6 domain of the RAPSN gene associated with congenital myasthenic syndrome. J Neurol Sci 2012; 316:112-5. [PMID: 22326364 DOI: 10.1016/j.jns.2012.01.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2011] [Revised: 12/20/2011] [Accepted: 01/13/2012] [Indexed: 10/14/2022]
Abstract
Congenital myasthenic syndromes (CMS) are rare genetic disorders characterized by impaired neuromuscular transmission. They are caused by mutations in synaptic, presynaptic and post synaptic proteins. Rapsyn is a postsynaptic peripheral membrane protein that anchors the nicotinic acetylcholine receptor to the motor endplate. CMS patients of Iraqi and Persian Jewish origin, carry a common founder mutation in the E box of the RAPSN promoter region (-38A-G) that causes impaired transcriptional activities of the promoter region. We describe a Persian Jewish family with two siblings affected with typical CMS, harboring the common heterozygous (-38A-G) E-box mutation associated with a previously unreported heterozygous p.224 insT causing an insertion of Threonine in the TPR6 domain. To the best of our knowledge, this is the first mutation in the TPR6 domain and might give supportive evidence to the role of this domain in rapsyn self association and consequently co-clustering with AchR in the post synaptic membrane.
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27
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Congenital myasthenic syndrome due to homozygous CHRNE mutations: report of patients in Arabia. J Neuroophthalmol 2011; 31:42-7. [PMID: 21150643 DOI: 10.1097/wno.0b013e3181f50bea] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
We describe the clinical characteristics of 3 siblings from 1 family with congenital myasthenic syndrome due to homozygous mutations of the gene coding for the epsilon subunit of the acetylcholine receptor (CHRNE). Onset of symptoms occurred in the first few months of life with ptosis, restricted ocular motility, mild proximal weakness, and difficulty swallowing. Multiple hospital admissions were required due to recurrent pulmonary infections. There was no decremental conduction on repetitive nerve stimulation, but jitter was increased on single fiber electromyographic. Since early childhood, our patients have done well without pulmonary or bulbar symptoms and with partial improvement on pyridostigmine therapy. Response of ptosis to diagnostic ice pack test was striking. Although these siblings have a clinical history and examination findings typical of homozygous CHRNE mutations, the clinical presentation of congenital myasthenia subtypes is variable, and accurate genotyping is essential in choosing the appropriate treatment.
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28
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Guergueltcheva V, Müller JS, Dusl M, Senderek J, Oldfors A, Lindbergh C, Maxwell S, Colomer J, Mallebrera CJ, Nascimento A, Vilchez JJ, Muelas N, Kirschner J, Nafissi S, Kariminejad A, Nilipour Y, Bozorgmehr B, Najmabadi H, Rodolico C, Sieb JP, Schlotter B, Schoser B, Herrmann R, Voit T, Steinlein OK, Najafi A, Urtizberea A, Soler DM, Muntoni F, Hanna MG, Chaouch A, Straub V, Bushby K, Palace J, Beeson D, Abicht A, Lochmüller H. Congenital myasthenic syndrome with tubular aggregates caused by GFPT1 mutations. J Neurol 2011; 259:838-50. [DOI: 10.1007/s00415-011-6262-z] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2011] [Revised: 09/13/2011] [Accepted: 09/15/2011] [Indexed: 02/04/2023]
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29
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Chaouch A, Müller JS, Guergueltcheva V, Dusl M, Schara U, Rakocević-Stojanović V, Lindberg C, Scola RH, Werneck LC, Colomer J, Nascimento A, Vilchez JJ, Muelas N, Argov Z, Abicht A, Lochmüller H. A retrospective clinical study of the treatment of slow-channel congenital myasthenic syndrome. J Neurol 2011; 259:474-81. [PMID: 21822932 DOI: 10.1007/s00415-011-6204-9] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2011] [Revised: 07/19/2011] [Accepted: 07/24/2011] [Indexed: 10/17/2022]
Abstract
Slow-channel congenital myasthenic syndrome (CMS) is a rare subtype of CMS caused by dominant "gain of function" mutations in the acetylcholine receptor. Clinically, the cervical and forearm extensor muscles seem to be preferentially weaker; and conventional treatment with anticholinesterases fails to improve symptoms. In contrast, open channel blockers such as fluoxetine and quinidine have been shown to be of benefit. The objectives of our study were to provide further insight into the clinical features of slow-channel CMS and evaluate response to recommended therapy. We carried out a retrospective clinical follow up study of 15 slow-channel CMS patients referred to the Munich CMS Centre. Detailed clinical data were collected by clinicians involved in the care of each patient, with a particular focus on response and tolerability to recommended therapy. Patients varied widely as regard onset of symptoms, severity of disease and mutations involved. Patients received up to four different medications and some had none. Our results strengthen previous reported findings in terms of clinical phenotype variability and the poor response to pyridostigmine. Although treatment with fluoxetine was beneficial in most patients, a number of our patients suffered significant adverse effects that hindered optimum dose titration or led to treatment cessation. Slow-channel CMS is rare and exhibits distinct clinical and genetic characteristics. Our study suggests that fluoxetine, despite being effective in most patients, can be associated with significant side effects, thus reducing treatment effectiveness in clinical practice.
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Affiliation(s)
- Amina Chaouch
- Institute of Genetic Medicine, Newcastle University, NE1 3BZ, Newcastle upon Tyne, UK
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30
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Witoonpanich R, Pulkes T, Dejthevaporn C, Yodnopklao P, Witoonpanich P, Wetchaphanphesat S, Brengman JM, Engel AG. Phenotypic heterogeneity in a large Thai slow-channel congenital myasthenic syndrome kinship. Neuromuscul Disord 2011; 21:214-8. [PMID: 21316238 DOI: 10.1016/j.nmd.2010.12.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2010] [Revised: 10/20/2010] [Accepted: 12/13/2010] [Indexed: 11/28/2022]
Abstract
The slow-channel congenital myasthenic syndrome (SCCMS) is an autosomal dominant neuromuscular disorder caused by mutations in different subunits of the acetylcholine receptor (AChR). We here report our clinical findings in three generations of a large Thai kinship suffering from SCCMS and trace the disease to the p.Gly153Ser mutation in the AChR α subunit. The same mutation had previously been reported only in Caucasian but not in Asian patients. The clinical features include ptosis, ophthalmoparesis, and weakness of the cervical and finger extensor muscles as well as marked phenotypic heterogeneity.
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Affiliation(s)
- Rawiphan Witoonpanich
- Division of Neurology, Department of Medicine, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand.
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31
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Barišić N, Chaouch A, Müller JS, Lochmüller H. Genetic heterogeneity and pathophysiological mechanisms in congenital myasthenic syndromes. Eur J Paediatr Neurol 2011; 15:189-96. [PMID: 21498094 DOI: 10.1016/j.ejpn.2011.03.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2011] [Accepted: 03/20/2011] [Indexed: 10/18/2022]
Abstract
Congenital myasthenic syndromes (CMS) are a rare heterogeneous group of inherited neuromuscular disorders associated with distinctive clinical, electrophysiological, ultrastructural and genetic abnormalities. These genetic defects either impair neuromuscular transmission directly or result in secondary impairments, which eventually compromise the safety margin of neuromuscular transmission. In this report we will explore the significant progress made in understanding the molecular pathogenesis of CMS, which is important for both patients and clinicians in terms of reaching a definite diagnosis and selecting the most appropriate treatment.
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Affiliation(s)
- Nina Barišić
- Department of Pediatrics, Medical School, University of Zagreb, 10000 Zagreb, Rebro, Kišpatićeva 12, Zagreb, Croatia.
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32
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Alseth EH, Maniaol AH, Elsais A, Nakkestad HL, Tallaksen C, Gilhus NE, Skeie GO. Investigation for RAPSN and DOK-7 mutations in a cohort of seronegative myasthenia gravis patients. Muscle Nerve 2011; 43:574-7. [DOI: 10.1002/mus.21919] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/14/2011] [Indexed: 11/12/2022]
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33
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Abstract
Paediatric electromyography (EMG) is an invaluable diagnostic test for the investigation of neuromuscular disease, but its use is inconsistent between and within different countries. One perception is that the procedure is painful; however, in comparison with common investigations performed routinely in children, EMG is better tolerated. While some developments, such as those within clinical genetics, would appear to mark its demise, paradoxically the more genetic abnormalities that are discovered in conditions such as hereditary neuropathy, the more precise a delineation of the phenotype is required. EMG has particular strengths in the diagnosis of neuropathies, motor neuronopathy and neuromuscular transmission disorders such as myasthenia. Also, it can supplement the investigation of myopathies. Areas of development include the diagnosis of myasthenia, delineation of bulbar palsy as a cause of dysphagia, more accurate and earlier prediction of prognosis in neonatal brachial palsy and investigation of channelopathies. It is a valuable diagnostic tool in developed countries and those with limited resources.
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Affiliation(s)
- Matthew Pitt
- Department of Clinical Neurophysiology, Great Ormond Street Hospital for Children NHS Trust, London, UK.
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34
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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] [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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35
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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] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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36
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Srour M, Bolduc V, Guergueltcheva V, Lochmüller H, Gendron D, Shevell MI, Poulin C, Mathieu J, Bouchard JP, Brais B. DOK7 mutations presenting as a proximal myopathy in French Canadians. Neuromuscul Disord 2010; 20:453-7. [DOI: 10.1016/j.nmd.2010.05.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2009] [Revised: 03/25/2010] [Accepted: 05/14/2010] [Indexed: 11/28/2022]
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37
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Ben Ammar A, Petit F, Alexandri N, Gaudon K, Bauché S, Rouche A, Gras D, Fournier E, Koenig J, Stojkovic T, Lacour A, Petiot P, Zagnoli F, Viollet L, Pellegrini N, Orlikowski D, Lazaro L, Ferrer X, Stoltenburg G, Paturneau-Jouas M, Hentati F, Fardeau M, Sternberg D, Hantaï D, Richard P, Eymard B. Phenotype genotype analysis in 15 patients presenting a congenital myasthenic syndrome due to mutations in DOK7. J Neurol 2009; 257:754-66. [DOI: 10.1007/s00415-009-5405-y] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2009] [Revised: 10/30/2009] [Accepted: 11/16/2009] [Indexed: 10/20/2022]
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38
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Huzé C, Bauché S, Richard P, Chevessier F, Goillot E, Gaudon K, Ben Ammar A, Chaboud A, Grosjean I, Lecuyer HA, Bernard V, Rouche A, Alexandri N, Kuntzer T, Fardeau M, Fournier E, Brancaccio A, Rüegg MA, Koenig J, Eymard B, Schaeffer L, Hantaï D. Identification of an agrin mutation that causes congenital myasthenia and affects synapse function. Am J Hum Genet 2009; 85:155-67. [PMID: 19631309 DOI: 10.1016/j.ajhg.2009.06.015] [Citation(s) in RCA: 132] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2009] [Revised: 06/16/2009] [Accepted: 06/23/2009] [Indexed: 11/16/2022] Open
Abstract
We report the case of a congenital myasthenic syndrome due to a mutation in AGRN, the gene encoding agrin, an extracellular matrix molecule released by the nerve and critical for formation of the neuromuscular junction. Gene analysis identified a homozygous missense mutation, c.5125G>C, leading to the p.Gly1709Arg variant. The muscle-biopsy specimen showed a major disorganization of the neuromuscular junction, including changes in the nerve-terminal cytoskeleton and fragmentation of the synaptic gutters. Experiments performed in nonmuscle cells or in cultured C2C12 myotubes and using recombinant mini-agrin for the mutated and the wild-type forms showed that the mutated form did not impair the activation of MuSK or change the total number of induced acetylcholine receptor aggregates. A solid-phase assay using the dystrophin glycoprotein complex showed that the mutation did not affect the binding of agrin to alpha-dystroglycan. Injection of wild-type or mutated agrin into rat soleus muscle induced the formation of nonsynaptic acetylcholine receptor clusters, but the mutant protein specifically destabilized the endogenous neuromuscular junctions. Importantly, the changes observed in rat muscle injected with mutant agrin recapitulated the pre- and post-synaptic modifications observed in the patient. These results indicate that the mutation does not interfere with the ability of agrin to induce postsynaptic structures but that it dramatically perturbs the maintenance of the neuromuscular junction.
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MESH Headings
- Adult
- Agrin/chemistry
- Agrin/genetics
- Agrin/metabolism
- Animals
- Biopsy
- Cell Line
- DNA Mutational Analysis
- Dystroglycans/metabolism
- Female
- Humans
- Male
- Models, Chemical
- Muscle Fibers, Skeletal/cytology
- Muscle Fibers, Skeletal/metabolism
- Muscle, Skeletal/metabolism
- Muscle, Skeletal/pathology
- Muscle, Skeletal/surgery
- Muscle, Skeletal/ultrastructure
- Mutation, Missense
- Myasthenic Syndromes, Congenital/genetics
- Neuromuscular Junction/genetics
- Neuromuscular Junction/metabolism
- Neuromuscular Junction/physiology
- Neuromuscular Junction/ultrastructure
- Pedigree
- Protein Structure, Tertiary
- Rats
- Receptors, Cholinergic/genetics
- Receptors, Cholinergic/metabolism
- Receptors, Cholinergic/physiology
- Recombinant Proteins/chemistry
- Recombinant Proteins/metabolism
- Synapses/metabolism
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Affiliation(s)
- Caroline Huzé
- Equipe Différenciation Neuromusculaire, UMR 5239, Ecole Normale Supérieure Lyon, CNRS, Université Lyon 1, Lyon, France
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39
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Yis U, Kurul SH, Oztura I, Ozden O, Akinci G, Dirik E. Temporary diazepam responsive apneic attacks and congenital myasthenic syndrome. J Child Neurol 2009; 24:895-8. [PMID: 19289695 DOI: 10.1177/0883073808331083] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Congenital myasthenic syndromes are a genetically and phenotypically heterogeneous group of hereditary disorders affecting neuromuscular junction. Mutations in the gene encoding choline acetyltransferase cause presynaptic defects. The missense mutation I336T has been identified in Turkish population, and most of the cases carrying this mutation present with exercise-induced fatigability and ptosis. Although apneic attacks occur in these cases during febrile illness in childhood, the number of reported respiratory distress episodes during infancy is scarce. Another important feature of these cases is that response to esterase inhibitors is satisfactory. We present a case of congenital myasthenic syndrome with I336T choline acetyltransferase mutation who presented with numerous attacks of respiratory distress in the infancy period. Interestingly, the patient had myopathic findings on electromyography and diazepam decreased severity of apneic attacks. There was also no improvement with esterase inhibitors.
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Affiliation(s)
- Uluç Yis
- Division of Child Neurology, Gaziantep Children's Hospital, Gaziantep, Turkey.
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40
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Abstract
A 59-year-old woman noted intermittent ptosis, diplopia, dysphagia, and proximal muscle weakness for several years. She had a strong family history of myasthenia gravis. Chest computed tomography and sternotomy revealed a micronodular spindle cell thymoma. Electromyography and antibody testing was negative for myasthenia gravis. Genetic testing confirmed a diagnosis of oculopharyngeal muscular dystrophy.
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41
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Lochmüller H, Griggs RC. New treatments for neuromuscular disease: optimism and obstacles. Neurotherapeutics 2008; 5:497-8. [PMID: 19019299 PMCID: PMC4514702 DOI: 10.1016/j.nurt.2008.08.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
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42
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Kinali M, Beeson D, Pitt M, Jungbluth H, Simonds A, Aloysius A, Cockerill H, Davis T, Palace J, Manzur A, Jimenez-Mallebrera C, Sewry C, Muntoni F, Robb S. Congenital Myasthenic Syndromes in childhood: Diagnostic and management challenges. J Neuroimmunol 2008; 201-202:6-12. [DOI: 10.1016/j.jneuroim.2008.06.026] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2008] [Revised: 06/07/2008] [Accepted: 06/09/2008] [Indexed: 10/21/2022]
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43
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Vignaud A, Fougerousse F, Mouisel E, Guerchet N, Hourde C, Bacou F, Butler-Browne GS, Chatonnet A, Ferry A. Genetic inactivation of acetylcholinesterase causes functional and structural impairment of mouse soleus muscles. Cell Tissue Res 2008; 333:289-96. [DOI: 10.1007/s00441-008-0640-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2008] [Revised: 05/06/2008] [Accepted: 05/08/2008] [Indexed: 11/28/2022]
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44
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Mihaylova V, Müller JS, Vilchez JJ, Salih MA, Kabiraj MM, D’Amico A, Bertini E, Wölfle J, Schreiner F, Kurlemann G, Rasic VM, Siskova D, Colomer J, Herczegfalvi A, Fabriciova K, Weschke B, Scola R, Hoellen F, Schara U, Abicht A, Lochmüller H. Clinical and molecular genetic findings in COLQ-mutant congenital myasthenic syndromes. Brain 2008; 131:747-59. [DOI: 10.1093/brain/awm325] [Citation(s) in RCA: 107] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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