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Ziaadini B, Ghaderi Yazdi B, Dirandeh E, Boostani R, Karimi N, Panahi A, Kariminejad A, Fadaee M, Ahangari F, Nafissi S. DOK7 congenital myasthenic syndrome: case series and review of literature. BMC Neurol 2024; 24:211. [PMID: 38907197 PMCID: PMC11191154 DOI: 10.1186/s12883-024-03713-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Accepted: 06/05/2024] [Indexed: 06/23/2024] Open
Abstract
BACKGROUND Congenital myasthenic syndromes (CMS) are among the most challenging differential diagnoses in the neuromuscular domain, consisting of diverse genotypes and phenotypes. A mutation in the Docking Protein 7 (Dok-7) is a common cause of CMS. DOK7 CMS requires different treatment than other CMS types. Regarding DOK7's special considerations and challenges ahead of neurologists, we describe seven DOK7 patients and evaluate their response to treatment. METHODS The authors visited these patients in the neuromuscular clinics of Tehran and Kerman Universities of Medical Sciences Hospitals. They diagnosed these patients based on clinical findings and neurophysiological studies, which Whole Exome Sequencing confirmed. For each patient, we tried unique medications and recorded the clinical response. RESULTS The symptoms started from birth to as late as the age of 33, with the mean age of onset being 12.5. Common symptoms were: Limb-girdle weakness in 6, fluctuating symptoms in 5, ptosis in 4, bifacial weakness in 3, reduced extraocular movement in 3, bulbar symptoms in 2 and dyspnea in 2 3-Hz RNS was decremental in 5 out of 6 patients. Salbutamol was the most effective. c.1124_1127dupTGCC is the most common variant; three patients had this variant. CONCLUSION We strongly recommend that neurologists consider CMS in patients with these symptoms and a similar familial history. We recommend prescribing salbutamol as the first-choice treatment option for DOK7 patients.
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Affiliation(s)
- Bentolhoda Ziaadini
- Neurology Research Center, Kerman University of Medical Sciences, Kerman, Iran
| | - Bardyia Ghaderi Yazdi
- Neuromuscular Research Center, Shariati Hospital, Tehran University of Medical Sciences, Shariati Hospital, North Karegar St, Tehran, 14117-13135, Iran
- Department of Neurology, Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran
| | - Elham Dirandeh
- Clinical Research Development Unit, Kowsar Educational, Research and Therapeutic Hospital, Semnan University of Medical Sciences, Semnan, Iran
| | - Reza Boostani
- Department of Neurology, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Narges Karimi
- Department of Neurology, School of Medicine, Immunogenetics Research Center, Toxoplasmosis Research Center, Clinical Research Development Unit of Bou Ali Sina Hospital, Mazandaran University of Medical Sciences, Sari, Iran
| | - Akram Panahi
- Neuromuscular Research Center, Shariati Hospital, Tehran University of Medical Sciences, Shariati Hospital, North Karegar St, Tehran, 14117-13135, Iran
- Department of Neurology, Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran
| | | | - Mahsa Fadaee
- Kariminejad-Najmabadi Pathology & Genetics Center, Tehran, Iran
| | | | - Shahriar Nafissi
- Neuromuscular Research Center, Shariati Hospital, Tehran University of Medical Sciences, Shariati Hospital, North Karegar St, Tehran, 14117-13135, Iran.
- Department of Neurology, Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran.
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Zirek F, Özcan G, Tekin MN, Uçar Çİ, Kartal AT, Balaban B, Kendirli T, Teber ST, Çobanoğlu N. An infant with episodic stridor and respiratory crises since birth: A challenging diagnosis. Pediatr Pulmonol 2024. [PMID: 38251867 DOI: 10.1002/ppul.26866] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/25/2023] [Revised: 01/02/2024] [Accepted: 01/05/2024] [Indexed: 01/23/2024]
Affiliation(s)
- Fazılcan Zirek
- Department of Pediatrics, Division of Pediatric Pulmonology, Faculty of Medicine, Ankara University, Ankara, Turkey
| | - Gizem Özcan
- Department of Pediatrics, Division of Pediatric Pulmonology, Faculty of Medicine, Ankara University, Ankara, Turkey
| | - Merve Nur Tekin
- Department of Pediatrics, Division of Pediatric Pulmonology, Faculty of Medicine, Ankara University, Ankara, Turkey
| | - Çiğdem İlter Uçar
- Department of Pediatrics, Division of Pediatric Neurology, Faculty of Medicine, Ankara University, Ankara, Turkey
| | - Ayşe Tuğba Kartal
- Department of Pediatrics, Division of Pediatric Neurology, Faculty of Medicine, Ankara University, Ankara, Turkey
| | - Burak Balaban
- Department of Pediatrics, Division of Pediatric Intensive Care Unit, Faculty of Medicine, Ankara University, Ankara, Turkey
| | - Tanıl Kendirli
- Department of Pediatrics, Division of Pediatric Intensive Care Unit, Faculty of Medicine, Ankara University, Ankara, Turkey
| | - Serap Tıraş Teber
- Department of Pediatrics, Division of Pediatric Neurology, Faculty of Medicine, Ankara University, Ankara, Turkey
| | - Nazan Çobanoğlu
- Department of Pediatrics, Division of Pediatric Pulmonology, Faculty of Medicine, Ankara University, Ankara, Turkey
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3
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Sarker S, Eshaque TB, Soorajkumar A, Nassir N, Zehra B, Kanta SI, Rahaman MA, Islam A, Akter S, Ali MK, Mim RA, Uddin KMF, Chowdhury MSJ, Shams N, Baqui MA, Lim ET, Akter H, Woodbury-Smith M, Uddin M. Mutational spectrum and phenotypic variability of Duchenne muscular dystrophy and related disorders in a Bangladeshi population. Sci Rep 2023; 13:21547. [PMID: 38057384 PMCID: PMC10700514 DOI: 10.1038/s41598-023-48982-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Accepted: 12/02/2023] [Indexed: 12/08/2023] Open
Abstract
Duchenne muscular dystrophy (DMD) is a severe rare neuromuscular disorder caused by mutations in the X-linked dystrophin gene. Several mutations have been identified, yet the full mutational spectrum, and their phenotypic consequences, will require genotyping across different populations. To this end, we undertook the first detailed genotype and phenotype characterization of DMD in the Bangladeshi population. We investigated the rare mutational and phenotypic spectrum of the DMD gene in 36 DMD-suspected Bangladeshi participants using an economically affordable diagnostic strategy involving initial screening for exonic deletions in the DMD gene via multiplex PCR, followed by testing PCR-negative patients for mutations using whole exome sequencing. The deletion mapping identified two critical DMD gene hotspot regions (near proximal and distal ends, spanning exons 8-17 and exons 45-53, respectively) that comprised 95% (21/22) of the deletions for this population cohort. From our exome analysis, we detected two novel pathogenic hemizygous mutations in exons 21 and 42 of the DMD gene, and novel pathogenic recessive and loss of function variants in four additional genes: SGCD, DYSF, COL6A3, and DOK7. Our phenotypic analysis showed that DMD suspected participants presented diverse phenotypes according to the location of the mutation and which gene was impacted. Our study provides ethnicity specific new insights into both clinical and genetic aspects of DMD.
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Affiliation(s)
- Shaoli Sarker
- Genetics and Genomic Medicine Centre (GGMC), NeuroGen Healthcare, Dhaka, Bangladesh
- Bangladesh Shishu Hospital and Institute, Dhaka, Bangladesh
| | | | - Anjana Soorajkumar
- Center for Applied and Translational Genomics (CATG), Mohammed Bin Rashid University of Medicine and Health Sciences, Dubai, UAE
| | - Nasna Nassir
- Center for Applied and Translational Genomics (CATG), Mohammed Bin Rashid University of Medicine and Health Sciences, Dubai, UAE
| | - Binte Zehra
- Center for Applied and Translational Genomics (CATG), Mohammed Bin Rashid University of Medicine and Health Sciences, Dubai, UAE
| | | | - Md Atikur Rahaman
- Genetics and Genomic Medicine Centre (GGMC), NeuroGen Healthcare, Dhaka, Bangladesh
| | - Amirul Islam
- Genetics and Genomic Medicine Centre (GGMC), NeuroGen Healthcare, Dhaka, Bangladesh
- GenomeArc Inc., Mississauga, Ontario, Canada
| | - Shimu Akter
- Genetics and Genomic Medicine Centre (GGMC), NeuroGen Healthcare, Dhaka, Bangladesh
| | - Mohammad Kawsar Ali
- Genetics and Genomic Medicine Centre (GGMC), NeuroGen Healthcare, Dhaka, Bangladesh
| | - Rabeya Akter Mim
- Genetics and Genomic Medicine Centre (GGMC), NeuroGen Healthcare, Dhaka, Bangladesh
| | - K M Furkan Uddin
- Genetics and Genomic Medicine Centre (GGMC), NeuroGen Healthcare, Dhaka, Bangladesh
| | | | - Nusrat Shams
- Genetics and Genomic Medicine Centre (GGMC), NeuroGen Healthcare, Dhaka, Bangladesh
| | - Md Abdul Baqui
- Department of Biochemistry, Holy Family Red Crescent Medical College and Hospital, Dhaka, Bangladesh
| | - Elaine T Lim
- Department of Genomics and Computational Biology, University of Massachusetts Chan Medical School, Worcester, MA, 01605, USA
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Chan Medical School, Worcester, MA, 01605, USA
| | - Hosneara Akter
- Genetics and Genomic Medicine Centre (GGMC), NeuroGen Healthcare, Dhaka, Bangladesh
| | - Marc Woodbury-Smith
- Biosciences Institute, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK.
| | - Mohammed Uddin
- Center for Applied and Translational Genomics (CATG), Mohammed Bin Rashid University of Medicine and Health Sciences, Dubai, UAE.
- GenomeArc Inc., Mississauga, Ontario, Canada.
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4
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Mendpara V, Bethanabotla S, Yadav M, Kanisetti V, Singh G, Das A, Sahu S, Patel H. When Breathing Becomes a Challenge: A Case of Congenital Myasthenia Gravis in an Indian Neonate With a DOK-7 Gene Mutation. Cureus 2023; 15:e38842. [PMID: 37303354 PMCID: PMC10256249 DOI: 10.7759/cureus.38842] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/10/2023] [Indexed: 06/13/2023] Open
Abstract
A rare neuromuscular condition known as congenital myasthenia gravis (CMG) affects some people from birth or very soon after. It results in fatigue and muscle weakness because of genetic abnormalities that interfere with the neuromuscular junction's ability to function, where the nerves and muscles connect. Even among those who have the same genetic mutation, the severity of CMG symptoms might differ considerably. The most typical signs of CMG include eyelid drooping, breathing issues, muscle weakness and weariness, and difficulties swallowing. Clinical examinations, neurophysiologic tests, and genetic analyses are frequently combined to make the diagnosis of CMG. Although there is no known treatment for CMG, many patients may control their symptoms and lead relatively normal lives with the right care. A newborn with CMG due to a DOK-7 gene mutation is described in this article, along with its very early onset. The DOK-7 mutation is a rare variant in the Indian population that causes CMG and usually manifests as 'limb girdle' weakness. However, due to muscle weakness, the neonate in this case developed severe respiratory distress and later died despite rigorous life-saving measures.
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Affiliation(s)
- Vaidehi Mendpara
- Medicine and Surgery, Pediatrics, Government Medical College Surat, Surat, IND
| | | | - Megha Yadav
- Medicine and Surgery, Maharani Laxmi Bai Medical College, Jhansi, IND
| | | | - Gurpreet Singh
- Medicine, Government Medical College and Hospital, Amritsar, IND
| | - Abhirami Das
- Internal Medicine, Rajiv Gandhi Medical College, Thane, IND
| | - Sweta Sahu
- Surgery, Jagadguru Jayadeva Murugarajendra (JJM) Medical College, Davanagere, IND
| | - Hitesh Patel
- Pediatrics and Child Health, Government Medical College and Hospital, Surat, IND
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5
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Ohno K, Ohkawara B, Shen XM, Selcen D, Engel AG. Clinical and Pathologic Features of Congenital Myasthenic Syndromes Caused by 35 Genes-A Comprehensive Review. Int J Mol Sci 2023; 24:ijms24043730. [PMID: 36835142 PMCID: PMC9961056 DOI: 10.3390/ijms24043730] [Citation(s) in RCA: 26] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2023] [Revised: 02/09/2023] [Accepted: 02/09/2023] [Indexed: 02/16/2023] Open
Abstract
Congenital myasthenic syndromes (CMS) are a heterogeneous group of disorders characterized by impaired neuromuscular signal transmission due to germline pathogenic variants in genes expressed at the neuromuscular junction (NMJ). A total of 35 genes have been reported in CMS (AGRN, ALG14, ALG2, CHAT, CHD8, CHRNA1, CHRNB1, CHRND, CHRNE, CHRNG, COL13A1, COLQ, DOK7, DPAGT1, GFPT1, GMPPB, LAMA5, LAMB2, LRP4, MUSK, MYO9A, PLEC, PREPL, PURA, RAPSN, RPH3A, SCN4A, SLC18A3, SLC25A1, SLC5A7, SNAP25, SYT2, TOR1AIP1, UNC13A, VAMP1). The 35 genes can be classified into 14 groups according to the pathomechanical, clinical, and therapeutic features of CMS patients. Measurement of compound muscle action potentials elicited by repetitive nerve stimulation is required to diagnose CMS. Clinical and electrophysiological features are not sufficient to identify a defective molecule, and genetic studies are always required for accurate diagnosis. From a pharmacological point of view, cholinesterase inhibitors are effective in most groups of CMS, but are contraindicated in some groups of CMS. Similarly, ephedrine, salbutamol (albuterol), amifampridine are effective in most but not all groups of CMS. This review extensively covers pathomechanical and clinical features of CMS by citing 442 relevant articles.
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Affiliation(s)
- Kinji Ohno
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
- Correspondence: (K.O.); (A.G.E.)
| | - Bisei Ohkawara
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Xin-Ming Shen
- Department of Neurology and Neuromuscular Research Laboratory, Mayo Clinic, Rochester, MN 55905, USA
| | - Duygu Selcen
- Department of Neurology and Neuromuscular Research Laboratory, Mayo Clinic, Rochester, MN 55905, USA
| | - Andrew G. Engel
- Department of Neurology and Neuromuscular Research Laboratory, Mayo Clinic, Rochester, MN 55905, USA
- Correspondence: (K.O.); (A.G.E.)
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6
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Webster RG, Vanhaesebrouck AE, Maxwell SE, Cossins JA, Liu W, Ueta R, Yamanashi Y, Beeson DMW. Effect of salbutamol on neuromuscular junction function and structure in a mouse model of DOK7 congenital myasthenia. Hum Mol Genet 2021; 29:2325-2336. [PMID: 32543656 PMCID: PMC7424765 DOI: 10.1093/hmg/ddaa116] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2020] [Revised: 06/07/2020] [Accepted: 06/08/2020] [Indexed: 12/28/2022] Open
Abstract
Congenital myasthenic syndromes (CMS) are characterized by fatigable muscle weakness resulting from impaired neuromuscular transmission. β2-adrenergic agonists are an effective treatment for DOK7-CMS. DOK7 is a component within the AGRN-LRP4-MUSK-DOK7 signalling pathway that is key for the formation and maintenance of the synaptic structure of the neuromuscular junction (NMJ). The precise mechanism of action of β2-adrenergic agonists at the NMJ is not fully understood. In this study, we investigated whether β2-adrenergic agonists improve both neurotransmission and structural integrity of the NMJ in a mouse model of DOK7-CMS. Ex-vivo electrophysiological techniques and microscopy of the NMJ were used to study the effect of salbutamol, a β2-adrenergic agonist, on synaptic structure and function. DOK7-CMS model mice displayed a severe phenotype with reduced weight gain and perinatal lethality. Salbutamol treatment improved weight gain and survival in DOK7 myasthenic mice. Model animals had fewer active NMJs, detectable by endplate recordings, compared with age-matched wild-type littermates. Salbutamol treatment increased the number of detectable NMJs during endplate recording. Correspondingly, model mice had fewer acetylcholine receptor-stained NMJs detected by fluorescent labelling, but following salbutamol treatment an increased number were detectable. The data demonstrate that salbutamol can prolong survival and increase NMJ number in a severe model of DOK7-CMS.
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Affiliation(s)
- Richard G Webster
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford OX3 9DS, UK
| | - An E Vanhaesebrouck
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford OX3 9DS, UK
| | - Susan E Maxwell
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford OX3 9DS, UK
| | - Judith A Cossins
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford OX3 9DS, UK
| | - Weiwei Liu
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford OX3 9DS, UK
| | - Ryo Ueta
- Division of Genetics, Department of Cancer Biology, Institute of Medical Science, The University of Tokyo, Tokyo 135-8550, Japan
| | - Yuji Yamanashi
- Division of Genetics, Department of Cancer Biology, Institute of Medical Science, The University of Tokyo, Tokyo 135-8550, Japan
| | - David M W Beeson
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford OX3 9DS, UK
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7
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Alsallum MS, Alshareef A, Abuzinadah AR, Bamaga AK, Dallol A. A novel DOK7 mutation causing congenital myasthenic syndrome with limb-girdle weakness: case series of three family members. Heliyon 2021; 7:e06869. [PMID: 34027146 PMCID: PMC8120944 DOI: 10.1016/j.heliyon.2021.e06869] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 11/05/2020] [Accepted: 04/16/2021] [Indexed: 11/12/2022] Open
Abstract
Congenital myasthenia syndrome (CMS) is a group of heterogeneous diseases affecting the neuromuscular endplate. CMS has a considerably different phenotypic presentations, with the onset time ranging from early infancy to late adulthood. Here, we report a case of a CMS due to a new DOK7 mutation in a 28-year-old man and two of his sisters, who have a pure limb-girdle weakness. DOK7 CMS has a varying presentation. Typically, the onset occurs in childhood with ptosis, bulbar symptoms, difficulty walking, weakness, and gait abnormality. This case sheds light on a novel DOK7 gene mutation with a unique presentation of CMS and provides insight into its unique phenotypic presentation.
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Affiliation(s)
- Mohammed S Alsallum
- Neurology Resident, King Abdulaziz University Hospital, P.O. Box: 80200, 21589, Jeddah, Saudi Arabia
| | - Aysha Alshareef
- King Abdulaziz University, Faculty of Medicine, King Abdulaziz University Hospital, Internal Medicine Department, Neurology Division, P.O. Box: 80200, 21589, Jeddah, Saudi Arabia.,Neuromuscular Unit, King Fahad Medical Research Center, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Ahmad R Abuzinadah
- King Abdulaziz University, Faculty of Medicine, King Abdulaziz University Hospital, Internal Medicine Department, Neurology Division, P.O. Box: 80200, 21589, Jeddah, Saudi Arabia.,Neuromuscular Unit, King Fahad Medical Research Center, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Ahmed K Bamaga
- Neuromuscular Unit, King Fahad Medical Research Center, King Abdulaziz University, Jeddah, Saudi Arabia.,King Abdulaziz University, Faculty of Medicine, King Abdulaziz University Hospital, Pediatric Department, Neurology Division, P.O. Box: 80200, 21589, Jeddah, Saudi Arabia
| | - Ashraf Dallol
- Center of Excellence in Genomic Medicine Research and Faculty of Applied Medical Sciences, King Abdulaziz University, P.O. Box: 80200, 21589, Saudi Arabia
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Radhakrishnan P, Shukla A, Girisha KM, Nayak SS. Biallelic c.1263dupC in DOK7 results in fetal akinesia deformation sequence. Am J Med Genet A 2019; 182:804-807. [PMID: 31880392 DOI: 10.1002/ajmg.a.61473] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Revised: 12/04/2019] [Accepted: 12/14/2019] [Indexed: 11/08/2022]
Abstract
Fetal akinesia deformation sequence (FADS) is a clinically and genetically heterogeneous condition. Pathogenic variants in DOK7 are known to cause myasthenic syndrome, congenital, 10 (MIM#254300) and, rarely (reported in a single family) lethal FADS. Herein, we describe a biallelic variant c.1263dupC in DOK7, known to cause congenital myasthenic syndrome 10, causing lethal FADS in a consanguineous family. The present report illustrates wide phenotypic variability caused by biallelic pathogenic variants in DOK7. We also describe the second family with FADS due to pathogenic variants in DOK7.
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Affiliation(s)
- Periyasamy Radhakrishnan
- Department of Medical Genetics, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, India
| | - Anju Shukla
- Department of Medical Genetics, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, India
| | - Katta M Girisha
- Department of Medical Genetics, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, India
| | - Shalini S Nayak
- Department of Medical Genetics, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, India
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9
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Abstract
INTRODUCTION Mutations in the Dok-7 gene (DOK7) underlie a congenital myasthenic syndrome (CMS) with a characteristic limb-girdle (LG) pattern of muscle weakness. Multiple clinical findings and a wide clinical heterogeneity have been identified in this form of CMS. METHODS We describe here 2 unrelated adult patients who presented with a LG CMS, caused by 2 compound heterozygous pathogenic sequence variants in DOK7: c.1124_1127dupTGCC (P.Ala378Serfs*30) and c.480C> A (p.Tyr160*). RESULTS Although both patients presented with severe proximal weakness consistent with LG myasthenia, one of the patients presented with additional distal muscle involvement in the lower extremities. By contrast, the other patient had severe bulbar and respiratory deficit requiring gastric tube feeding and mechanical ventilatory support for most parts of the day. DISCUSSION These 2 cases illustrate the lack of phenotype-genotype correlation and the absence of geographic, genetic, and ethnic association in cases of LG CMS caused by DOK7 mutations.
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10
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11
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Santos M, Cruz S, Peres J, Santos L, Tavares P, Basto JP, Salgado V, Valverde AH. DOK7 myasthenic syndrome with subacute adult onset during pregnancy and partial response to fluoxetine. Neuromuscul Disord 2018; 28:278-282. [DOI: 10.1016/j.nmd.2017.12.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Revised: 12/02/2017] [Accepted: 12/04/2017] [Indexed: 02/04/2023]
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12
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Engel AG. Genetic basis and phenotypic features of congenital myasthenic syndromes. HANDBOOK OF CLINICAL NEUROLOGY 2018; 148:565-589. [PMID: 29478601 DOI: 10.1016/b978-0-444-64076-5.00037-5] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/06/2022]
Abstract
The congenital myasthenic syndromes (CMS) are heterogeneous disorders in which the safety margin of neuromuscular transmission is compromised by one or more specific mechanisms. The disease proteins reside in the nerve terminal, the synaptic basal lamina, or in the postsynaptic region, or at multiple sites at the neuromuscular junction as well as in other tissues. Targeted mutation analysis by Sanger or exome sequencing has been facilitated by characteristic phenotypic features of some CMS. No fewer than 20 disease genes have been recognized to date. In one-half of the currently identified probands, the disease stems from mutations in genes encoding subunits of the muscle form of the acetylcholine receptor (CHRNA1, CHRNB, CHRNAD1, and CHRNE). In 10-14% of the probands the disease is caused by mutations in RAPSN, DOK 7, or COLQ, and in 5% by mutations in CHAT. Other less frequently identified disease genes include LAMB2, AGRN, LRP4, MUSK, GFPT1, DPAGT1, ALG2, and ALG 14 as well as SCN4A, PREPL, PLEC1, DNM2, and MTM1. Identification of the genetic basis of each CMS is important not only for genetic counseling and disease prevention but also for therapy, because therapeutic agents that benefit one type of CMS can be harmful in another.
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Affiliation(s)
- Andrew G Engel
- Department of Neurology, Mayo Clinic College of Medicine, Rochester, MN, United States.
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Bevilacqua JA, Lara M, Díaz J, Campero M, Vázquez J, Maselli RA. Congenital Myasthenic Syndrome due to DOK7 mutations in a family from Chile. Eur J Transl Myol 2017; 27:6832. [PMID: 29118959 PMCID: PMC5658635 DOI: 10.4081/ejtm.2017.6832] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Revised: 08/16/2017] [Accepted: 08/16/2017] [Indexed: 01/15/2023] Open
Abstract
Congenital myasthenic syndromes (CMS) are neuromuscular transmission disorders caused by mutations in genes encoding neuromuscular junction proteins. A 61-year-old female and her older sister showed bilateral ptosis, facial and proximal limb weakness, and scoliosis since childhood. Another female sibling had milder signs, while other family members were asymptomatic. Facial nerve repetitive stimulation in the proband showed decrement of muscle responses. Single fiber EMG revealed increased jitter and blocking. Muscle biopsy showed type 2-fiber atrophy, without tubular aggregates. Mutational analysis in the three affected siblings revealed two compound heterozygous mutations in DOK7: c.1457delC, that predicts p.Pro486Argfs*13 and truncates the protein C-terminal domain, and c.473G>A, that predicts p.Arg158Gln and disruption of the dok7-MuSK interaction in the phosphotyrosine binding (PTB) domain. Unaffected family members carried only one or neither mutation. Discussion Two of the affected sisters showed marked improvement with salbutamol treatment, which illustrates the benefits of a correct diagnosis and treatment of DOK7-CMS.
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Affiliation(s)
- Jorge A. Bevilacqua
- Full Professor. Unidad Neuromuscular, Departamento de Neurología y Neurocirugía, Hospital Clínico Universidad de Chile (HCUCH), Santos Dumont 999, 2º piso, Sector E. Independencia 8380456; Santiago, Chile. +56 2 27773882; +56 2 27378546 E-mails of co-authors Marian Lara: Jorge Díaz: Mario Campero: Jessica Vázquez: Ricardo A. Maselli:
| | - Marian Lara
- Department of Neurology, University of California Davis, Davis CA, USA
| | - Jorge Díaz
- Department of Radiology, University of Chile Clinical Hospital (HCUCH), Santiago, Chile
| | - Mario Campero
- Neuromuscular Unit, Department of Neurology and Neurosurgery, University of Chile Clinical Hospital (HCUCH), Santiago, Chile
| | - Jessica Vázquez
- Department of Neurology, University of California Davis, Davis CA, USA
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Ng F, Lee DC, Schrumpf LA, Mazurek ME, Lee Lo V, Gill SK, Maselli RA. Effect of 3,4-diaminopyridine at the murine neuromuscular junction. Muscle Nerve 2016; 55:223-231. [PMID: 27251582 DOI: 10.1002/mus.25208] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Revised: 05/19/2016] [Accepted: 05/31/2016] [Indexed: 11/09/2022]
Abstract
INTRODUCTION We investigated the effects of 3,4-diaminopyridine (3,4-DAP) and its acetylated metabolite, N-(4-amino-pyridin-3-yl) acetamide (3-Ac), at the mammalian neuromuscular junction. METHODS Quantal release of acetylcholine was studied in diaphragm muscles of mice, using in vitro intracellular microelectrode recordings. RESULTS Under conditions of low probability of release, 3,4-DAP produced a 1,000% increase in quantal release, but 3-Ac had no effect. Under conditions of normal probability of release, the effect of 3,4-DAP was modest and limited by concurrent depletion of synaptic vesicles, especially with high concentrations of 3,4-DAP and high frequencies of nerve stimulation. CONCLUSIONS These findings predict 3,4-DAP is most effective in conditions with low probability of quantal release, such as Lambert-Eaton myasthenic syndrome. A beneficial effect is also expected in disorders of neuromuscular transmission in which the effect of 3,4-DAP on quantal release is not limited by depletion of synaptic vesicles, such as postsynaptic congenital myasthenic syndromes. Muscle Nerve, 2016 Muscle Nerve 55: 223-231, 2017.
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Affiliation(s)
- Fiona Ng
- University of California, Davis School of Medicine Department of Neurology, University of California Davis, Davis, California, USA
| | - Diana C Lee
- University of California, Davis School of Medicine Department of Neurology, University of California Davis, Davis, California, USA
| | - Leah A Schrumpf
- University of California, Davis School of Medicine Department of Neurology, University of California Davis, Davis, California, USA
| | - Mary E Mazurek
- University of California, Davis School of Medicine Department of Neurology, University of California Davis, Davis, California, USA
| | - Victoria Lee Lo
- University of California, Davis School of Medicine Department of Neurology, University of California Davis, Davis, California, USA
| | - Sharleen K Gill
- University of California, Davis School of Medicine Department of Neurology, University of California Davis, Davis, California, USA
| | - Ricardo A Maselli
- University of California, Davis School of Medicine Department of Neurology, University of California Davis, Davis, California, USA
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15
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Abstract
Stridor is a variably pitched respiratory sound, caused by abnormal air passage during breathing and often is the most prominent sign of upper airway obstruction. It is usually heard on inspiration (typically resulting from supraglottic or glottic obstruction) but also can occur on expiration (originating from obstruction at or below glottic level and/or severe upper airway obstruction). Stridor due to congenital anomalies may exist from birth or may develop within days, weeks or months. Various congenital and acquired disorders prevail in neonates, infants, children, and adolescents, and have to be distinguished. History, age of the child and physical examination together often allow a presumptive diagnosis. Further investigations may be necessary to establish a definite diagnosis, and flexible airway endoscopy is the diagnostic procedure of choice in most circumstances ("stridor is visible").
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Affiliation(s)
- Andreas Pfleger
- Division of Paediatric Pulmonology and Allergology, Department of Paediatrics and Adolescent Medicine, Medical University of Graz, Austria
| | - Ernst Eber
- Division of Paediatric Pulmonology and Allergology, Department of Paediatrics and Adolescent Medicine, Medical University of Graz, Austria.
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16
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Engel AG, Shen XM, Selcen D, Sine SM. Congenital myasthenic syndromes: pathogenesis, diagnosis, and treatment. Lancet Neurol 2015; 14:420-34. [PMID: 25792100 PMCID: PMC4520251 DOI: 10.1016/s1474-4422(14)70201-7] [Citation(s) in RCA: 336] [Impact Index Per Article: 37.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The congenital myasthenic syndromes (CMS) are a diverse group of genetic disorders caused by abnormal signal transmission at the motor endplate, a special synaptic contact between motor axons and each skeletal muscle fibre. Most CMS stem from molecular defects in the muscle nicotinic acetylcholine receptor, but they can also be caused by mutations in presynaptic proteins, mutations in proteins associated with the synaptic basal lamina, defects in endplate development and maintenance, or defects in protein glycosylation. The specific diagnosis of some CMS can sometimes be reached by phenotypic clues pointing to the mutated gene. In the absence of such clues, exome sequencing is a useful technique for finding the disease gene. Greater understanding of the mechanisms of CMS have been obtained from structural and electrophysiological studies of the endplate, and from biochemical studies. Present therapies for the CMS include cholinergic agonists, long-lived open-channel blockers of the acetylcholine receptor ion channel, and adrenergic agonists. Although most CMS are treatable, caution should be exercised as some drugs that are beneficial in one syndrome can be detrimental in another.
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Affiliation(s)
- Andrew G Engel
- Department of Neurology, Mayo Clinic, Rochester, MN, USA.
| | - Xin-Ming Shen
- Department of Neurology, Mayo Clinic, Rochester, MN, USA
| | - Duygu Selcen
- Department of Neurology, Mayo Clinic, Rochester, MN, USA
| | - Steven M Sine
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN, USA
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17
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Vrinten C, van der Zwaag AM, Weinreich SS, Scholten RJPM, Verschuuren JJGM. Ephedrine for myasthenia gravis, neonatal myasthenia and the congenital myasthenic syndromes. Cochrane Database Syst Rev 2014; 2014:CD010028. [PMID: 25515947 PMCID: PMC7387729 DOI: 10.1002/14651858.cd010028.pub2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
BACKGROUND Myasthenia is a condition in which neuromuscular transmission is affected by antibodies against neuromuscular junction components (autoimmune myasthenia gravis, MG; and neonatal myasthenia gravis, NMG) or by defects in genes for neuromuscular junction proteins (congenital myasthenic syndromes, CMSs). Clinically, some individuals seem to benefit from treatment with ephedrine, but its effects and adverse effects have not been systematically evaluated. OBJECTIVES To assess the effects and adverse effects of ephedrine in people with autoimmune MG, transient neonatal MG, and the congenital myasthenic syndromes. SEARCH METHODS On 17 November 2014, we searched the Cochrane Neuromuscular Disease Group Specialized Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE and EMBASE. We also searched reference lists of articles, conference proceedings of relevant conferences, and prospective trial registers. In addition, we contacted manufacturers and researchers in the field. SELECTION CRITERIA We considered randomised controlled trials (RCTs) and quasi-RCTs comparing ephedrine as a single or add-on treatment with any other active treatment, placebo, or no treatment in adults or children with autoimmune MG, NMG, or CMSs. DATA COLLECTION AND ANALYSIS Two review authors independently assessed study design and quality, and extracted data. We contacted study authors for additional information. We collected information on adverse effects from included articles, and contacted authors. MAIN RESULTS We found no RCTs or quasi-RCTs, and therefore could not establish the effect of ephedrine on MG, NMG and CMSs. We describe the results of 53 non-randomised studies narratively in the Discussion section, including observations of endurance, muscle strength and quality of life. Effects may differ depending on the type of myasthenia. Thirty-seven studies were in participants with CMS, five in participants with MG, and in 11 the precise form of myasthenia was unknown. We found no studies for NMG. Reported adverse effects included tachycardia, sleep disturbances, nervousness, and withdrawal symptoms. AUTHORS' CONCLUSIONS There was no evidence available from RCTs or quasi-RCTs, but some observations from non-randomised studies are available. There is a need for more evidence from suitable forms of prospective RCTs, such as series of n-of-one RCTs, that use appropriate and validated outcome measures.
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Affiliation(s)
- Charlotte Vrinten
- VU University Medical CenterCommunity Genetics Section, Clinical GeneticsBS7, D450PO Box 7057AmsterdamNetherlands1007 MB
| | - Angeli M van der Zwaag
- VU University Medical CenterCommunity Genetics Section, Clinical GeneticsBS7, D450PO Box 7057AmsterdamNetherlands1007 MB
| | - Stephanie S Weinreich
- VU University Medical CenterCommunity Genetics Section, Clinical GeneticsBS7, D450PO Box 7057AmsterdamNetherlands1007 MB
| | - Rob JPM Scholten
- Julius Center for Health Sciences and Primary Care / University Medical Center UtrechtDutch Cochrane CentreRoom Str. 6.126P.O. Box 85500UtrechtNetherlands3508 GA
| | - Jan JGM Verschuuren
- Leiden University Medical CenterDepartment of NeurologyPO Box 9600LeidenNetherlands2300 RC
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18
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Abstract
PURPOSE OF REVIEW Congenital myasthenic syndromes (CMSs) form a heterogeneous group of genetic diseases characterized by a dysfunction of neuromuscular transmission because of mutations in numerous genes. This review will focus on the causative genes recently identified and on the therapy of CMSs. RECENT FINDINGS Advances in exome sequencing allowed the discovery of a new group of genes that did not code for the known molecular components of the neuromuscular junction, and the definition of a new group of glycosylation-defective CMS. Rather than the specific drugs used, some of them having been known for decades, it is the rigorous therapeutic strategy that is now offered to the patient in relation to the identified mutated gene that is novel and promising. SUMMARY In addition to the above main points, we also present new data on the genes that were already known with an emphasis on the clinic and on animal models that may be of use to understand the pathophysiology of the disease. We also stress not only the diagnosis difficulties between congenital myopathies and CMSs, but also the continuum that may exist between the two.
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19
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Klein A, Pitt MC, McHugh JC, Niks EH, Sewry CA, Phadke R, Feng L, Manzur AY, Tirupathi S, DeVile C, Jayawant S, Finlayson S, Palace J, Muntoni F, Beeson D, Robb SA. DOK7 congenital myasthenic syndrome in childhood: Early diagnostic clues in 23 children. Neuromuscul Disord 2013; 23:883-91. [DOI: 10.1016/j.nmd.2013.06.002] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Revised: 05/24/2013] [Accepted: 06/05/2013] [Indexed: 10/26/2022]
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20
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Maselli RA, Arredondo J, Nguyen J, Lara M, Ng F, Ngo M, Pham JM, Yi Q, Stajich JM, McDonald K, Hauser MA, Wollmann RL. Exome sequencing detection of two untranslated GFPT1 mutations in a family with limb-girdle myasthenia. Clin Genet 2013; 85:166-71. [PMID: 23488891 DOI: 10.1111/cge.12118] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2012] [Revised: 02/01/2013] [Accepted: 02/01/2013] [Indexed: 11/26/2022]
Abstract
The term 'limb-girdle myasthenia' (LGM) was first used to describe three siblings with proximal limb weakness without oculobulbar involvement, but with EMG decrement and responsiveness to anticholinesterase medication. We report here that exome sequencing in the proband of this family revealed several sequence variations in genes linked to proximal limb weakness. However, the only mutations that cosegregated with disease were an intronic IVS7-8A>G mutation and the previously reported 3'-UTR c.*22C>A mutation in GFPT1, a gene linked to LGM. A minigene assay showed that IVS7-8A>G activates an alternative splice acceptor that results in retention of the last seven nucleotides of intron 7 and a frameshift leading to a termination codon 13 nucleotides downstream from the new splice site. An anconeus muscle biopsy revealed mild reduction of the axon terminal size and postsynaptic fold simplification. The amplitudes of miniature endplate potentials and quantal release were also diminished. The DNA of the mildly affected father of the proband showed only the intronic mutation along with sequence variations in other genes potentially relevant to LGM. Thus, this study performed in the family originally described with LGM showed two GFPT1 untranslated mutations, which may cause disease by reducing GFPT1 expression and ultimately impairing protein glycosylation.
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Affiliation(s)
- R A Maselli
- Department of Neurology, University of California Davis, Davis, CA, USA
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21
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Maselli RA, Arredondo J, Ferns MJ, Wollmann RL. Synaptic basal lamina-associated congenital myasthenic syndromes. Ann N Y Acad Sci 2013; 1275:36-48. [PMID: 23278576 DOI: 10.1111/j.1749-6632.2012.06807.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Proteins associated with the basal lamina (BL) participate in complex signal transduction processes that are essential for the development and maintenance of the neuromuscular junction (NMJ). Most important junctional BL proteins are collagens, such as collagen IV (α3-6), collagen XIII, and ColQ; laminins; nidogens; and heparan sulfate proteoglycans, such as perlecan and agrin. Mice lacking Colq (Colq(-/-)), laminin β2 (Lamb2(-/-)), or collagen XIII (Col13a1(-/-)) show immature nerve terminals enwrapped by Schwann cell projections that invaginate into the synaptic cleft and decrease contact surface for neurotransmission. Human mutations in COLQ, LAMB2, and AGRN cause congenital myasthenic syndromes (CMSs) owing to deficiency of ColQ, laminin-β2, and agrin, respectively. In these syndromes the NMJ ultrastructure shows striking resemblance to that of mice lacking the corresponding protein; furthermore, the extracellular localization of mutant proteins may provide favorable conditions for replacement strategies based on gene therapy and stem cells.
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Affiliation(s)
- Ricardo A Maselli
- Department of Neurology, University of California, Davis, California, USA.
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22
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Abstract
Congenital myasthenic syndromes (CMS) are a heterogeneous group of disorders caused by genetic defects affecting neuromuscular transmission and leading to muscle weakness accentuated by exertion. The characterization of CMS comprises two complementary steps: establishing the diagnosis and identifying the pathophysiological type of CMS. The combination of clinical, electrophysiological, and morphological studies allows the physician to refer a given CMS to mutation(s) in one of the 18 causative genes discovered to date and, in turn, to classify the CMS according to the location of the mutated proteins at the neuromuscular junction into presynaptic compartment, synaptic basal lamina, and postsynaptic compartment CMS. This complete characterization is essential for counseling and therapy of the patient, depending on the molecular background of the respective CMS. Despite comprehensive characterization, the phenotypic expression of one given gene involved is variable, and the etiology of many CMS remains to be discovered.
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Affiliation(s)
- Bruno Eymard
- Reference Center for Neuromuscular Diseases, Institute of Myology, Pitié-Salpêtrière Hospital, Paris, France
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23
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Maselli RA, Fernandez JM, Arredondo J, Navarro C, Ngo M, Beeson D, Cagney Ó, Williams DC, Wollmann RL, Yarov-Yarovoy V, Ferns MJ. LG2 agrin mutation causing severe congenital myasthenic syndrome mimics functional characteristics of non-neural (z-) agrin. Hum Genet 2012; 131:1123-35. [PMID: 22205389 PMCID: PMC4795461 DOI: 10.1007/s00439-011-1132-4] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2011] [Accepted: 12/11/2011] [Indexed: 10/14/2022]
Abstract
We describe a severe form of congenital myasthenic syndrome (CMS) caused by two heteroallelic mutations: a nonsense and a missense mutation in the gene encoding agrin (AGRN). The identified mutations, Q353X and V1727F, are located at the N-terminal and at the second laminin G-like (LG2) domain of agrin, respectively. A motor-point muscle biopsy demonstrated severe disruption of the architecture of the neuromuscular junction (NMJ), including: dispersion and fragmentation of endplate areas with normal expression of acetylcholinesterase; simplification of postsynaptic membranes; pronounced reduction of the axon terminal size; widening of the primary synaptic cleft; and, collection of membranous debris material in the primary synaptic cleft and in the subsynaptic cytoplasm. Expression studies in heterologous cells revealed that the Q353X mutation abolished expression of full-length agrin. Moreover, the V1727F mutation decreased agrin-induced clustering of the acetylcholine receptor (AChR) in cultured C2 muscle cells by >100-fold, and phosphorylation of the MuSK receptor and AChR beta subunit by ~tenfold. Surprisingly, the V1727F mutant also displayed increased binding to α-dystroglycan but decreased binding to a neural (z+) agrin-specific antibody. Our findings demonstrate that agrin mutations can associate with a severe form of CMS and cause profound distortion of the architecture and function of the NMJ. The impaired ability of V1727F agrin to activate MuSK and cluster AChRs, together with its increased affinity to α-dystroglycan, mimics non-neural (z-) agrin and are important determinants of the pathogenesis of the disease.
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MESH Headings
- Acetylcholinesterase/metabolism
- Adult
- Agrin/chemistry
- Agrin/genetics
- Agrin/metabolism
- Base Sequence
- Cell Line
- Codon, Nonsense
- Dystroglycans/metabolism
- Female
- HEK293 Cells
- Humans
- Male
- Models, Molecular
- Muscle Fibers, Skeletal/metabolism
- Muscle Fibers, Skeletal/pathology
- Muscle, Skeletal/metabolism
- Muscle, Skeletal/pathology
- Muscle, Skeletal/physiopathology
- Mutation, Missense
- Myasthenic Syndromes, Congenital/genetics
- Myasthenic Syndromes, Congenital/metabolism
- Neuromuscular Junction/metabolism
- Neuromuscular Junction/pathology
- Pedigree
- Receptors, Cholinergic/genetics
- Receptors, Cholinergic/metabolism
- Sequence Analysis, DNA
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Affiliation(s)
- Ricardo A. Maselli
- Department of Neurology, University of California Davis, Davis, California, 95616 USA
| | - Jose M. Fernandez
- Service of Clinical Neurophysiology. University Hospital of Vigo, Vigo (Pontevedra), Spain
| | - Juan Arredondo
- Department of Neurology, University of California Davis, Davis, California, 95616 USA
| | - Carmen Navarro
- Department of Pathology, University Hospital of Vigo and CIBERER (Centro de Investigacion Biomedica en Red en Enfermedades Raras), Vigo (Pontevedra), Spain
| | - Maian Ngo
- Department of Neurology, University of California Davis, Davis, California, 95616 USA
| | - David Beeson
- Neurosciences Group, Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, UK
| | - Órla Cagney
- Department of Neurology, University of California Davis, Davis, California, 95616 USA
| | - D. Colette Williams
- Veterinary Medical Teaching Hospital, University of California Davis, Davis, California, 95616, USA
| | - Robert L. Wollmann
- Department of Pathology, University of Chicago, Chicago, Illinois, 60637, USA
| | - Vladimir Yarov-Yarovoy
- Department of Physiology and Membrane Biology, University of California Davis, Davis, California 95616, USA
| | - Michael J Ferns
- Department of Physiology and Membrane Biology, University of California Davis, Davis, California 95616, USA
- Department of Anesthesiology, University of California Davis, Davis, California 95616, USA
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24
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Cossins J, Liu WW, Belaya K, Maxwell S, Oldridge M, Lester T, Robb S, Beeson D. The spectrum of mutations that underlie the neuromuscular junction synaptopathy in DOK7 congenital myasthenic syndrome. Hum Mol Genet 2012; 21:3765-75. [PMID: 22661499 DOI: 10.1093/hmg/dds198] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Congenital myasthenic syndromes (CMS) are a group of inherited diseases that affect synaptic transmission at the neuromuscular junction and result in fatiguable muscle weakness. A subgroup of CMS patients have a recessively inherited limb-girdle pattern of weakness caused by mutations in DOK7. DOK7 encodes DOK7, an adaptor protein that is expressed in the skeletal muscle and heart and that is essential for the development and maintenance of the neuromuscular junction. We have screened the DOK7 gene for mutations by polymerase chain reaction amplification and bi-directional sequencing of exonic and promoter regions and performed acetylcholine receptor (AChR) clustering assays and used exon trapping to determine the pathogenicity of detected variants. Approximately 18% of genetically diagnosed CMSs in the UK have mutations in DOK7, with mutations in this gene identified in more than 60 kinships to date. Thirty-four different pathogenic mutations were identified as well as 27 variants likely to be non-pathogenic. An exon 7 frameshift duplication c.1124_1127dupTGCC is commonly found in at least one allele. We analyse the effect of the common frameshift c.1124_1127dupTGCC and show that 10/11 suspected missense mutations have a deleterious effect on AChR clustering. We identify for the first time homozygous or compound heterozygous mutations that are localized 5' to exon 7. In addition, three silent variants in the N-terminal half of DOK7 are predicted to alter the splicing of the DOK7 RNA transcript. The DOK7 gene is highly polymorphic, and within these many variants, we define a spectrum of mutations that can underlie DOK7 CMS that will inform in managing this disorder.
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Affiliation(s)
- Judith Cossins
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, Headington, Oxford OX3 9DS, UK
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25
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Mori S, Yamada S, Kubo S, Chen J, Matsuda S, Shudou M, Maruyama N, Shigemoto K. Divalent and monovalent autoantibodies cause dysfunction of MuSK by distinct mechanisms in a rabbit model of myasthenia gravis. J Neuroimmunol 2012; 244:1-7. [DOI: 10.1016/j.jneuroim.2011.12.005] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2011] [Revised: 11/07/2011] [Accepted: 12/05/2011] [Indexed: 12/21/2022]
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26
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Engel AG. Current status of the congenital myasthenic syndromes. Neuromuscul Disord 2012; 22:99-111. [PMID: 22104196 PMCID: PMC3269564 DOI: 10.1016/j.nmd.2011.10.009] [Citation(s) in RCA: 107] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2011] [Revised: 10/11/2011] [Accepted: 10/13/2011] [Indexed: 01/04/2023]
Abstract
Congenital myasthenic syndromes (CMS) are heterogeneous disorders in which the safety margin of neuromuscular transmission is compromised by one or more specific mechanisms. Clinical, electrophysiologic, and morphologic studies have paved the way for detecting CMS-related mutations in proteins residing in the nerve terminal, the synaptic basal lamina, and in the postsynaptic region of the motor endplate. The disease proteins identified to date include choline acetyltransferase (ChAT), the endplate species of acetylcholinesterase (AChE), β2-laminin, the acetylcholine receptor (AChR), rapsyn, plectin, Na(v)1.4, the muscle specific protein kinase (MuSK), agrin, downstream of tyrosine kinase 7 (Dok-7), and glutamine-fructose-6-phosphate transaminase 1 (GFPT1). Myasthenic syndromes associated with centronuclear myopathies were recently recognized. Analysis of properties of expressed mutant proteins contributed to finding improved therapy for most CMS. Despite these advances, the molecular basis of some phenotypically characterized CMS remains elusive. Moreover, other types of CMS and disease genes likely exist and await discovery.
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Affiliation(s)
- Andrew G Engel
- Department of Neurology, Mayo Clinic, Rochester, MN 55905, United States.
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27
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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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28
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Maselli RA, Arredondo J, Cagney O, Mozaffar T, Skinner S, Yousif S, Davis RR, Gregg JP, Sivak M, Konia TH, Thomas K, Wollmann RL. Congenital myasthenic syndrome associated with epidermolysis bullosa caused by homozygous mutations in PLEC1 and CHRNE. Clin Genet 2010; 80:444-51. [PMID: 21175599 DOI: 10.1111/j.1399-0004.2010.01602.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Mutations in the plectin gene (PLEC1) cause epidermolysis bullosa simplex (EBS), which may associate with muscular dystrophy (EBS-MD) or pyloric atresia (EBS-PA). The association of EBS with congenital myasthenic syndrome (CMS) is also suspected to result from PLEC1 mutations. We report here a consanguineous patient with EBS and CMS for whom mutational analysis of PLEC1 revealed a homozygous 36 nucleotide insertion (1506_1507ins36) that results in a reduced expression of PLEC1 mRNA and plectin in the patient muscle. In addition, mutational analysis of CHRNE revealed a homozygous 1293insG, which is a well-known low-expressor receptor mutation. A skin biopsy revealed signs of EBS, and an anconeus muscle biopsy showed signs of a mild myopathy. Endplate studies showed fragmentation of endplates, postsynaptic simplification, and large collections of thread-like mitochondria. Amplitudes of miniature endplate potentials were diminished, but the endplate quantal content was actually increased. The complex phenotype presented here results from mutations in two separate genes. While the skin manifestations are because of the PLEC1 mutation, footprints of mutations in PLEC1 and CHRNE are present at the neuromuscular junction of the patient indicating that abnormalities in both genes contribute to the CMS phenotype.
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Affiliation(s)
- R A Maselli
- Department of Neurology, University of California Davis, USA.
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29
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Jephson CG, Mills NA, Pitt MC, Beeson D, Aloysius A, Muntoni F, Robb SA, Bailey CM. Congenital stridor with feeding difficulty as a presenting symptom of Dok7 congenital myasthenic syndrome. Int J Pediatr Otorhinolaryngol 2010; 74:991-4. [PMID: 20554332 DOI: 10.1016/j.ijporl.2010.05.022] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2010] [Revised: 05/17/2010] [Accepted: 05/18/2010] [Indexed: 10/19/2022]
Abstract
OBJECTIVE The congenital myasthenic syndromes (CMS) are a group of genetic disorders of neuromuscular transmission causing fatigable weakness. Symptoms may be present from birth, but diagnosis is often delayed for several years, notably in post-synaptic CMS due to mutations in the DOK7 gene. Recently, we noted a subgroup of children with CMS in whom congenital stridor and bilateral vocal cord palsy predated other symptoms. All had mutations in the DOK7 gene. The purpose of this study was to review our population of DOK7 CMS patients with congenital stridor and assess whether there were other phenotypic features which might raise suspicion of a diagnosis of CMS in the neonatal period, in the absence of limb weakness and ptosis and prompt earlier referral for neurophysiological investigation, genetic diagnosis and appropriate treatment. METHODS A retrospective case review of 11 DOK7 CMS patients at a tertiary referral centre. RESULTS Six patients were identified with DOK7 mutations and congenital stridor, four requiring intubation soon after birth. Four patients had a diagnosis of bilateral vocal cord palsy and three required tracheostomy, successfully decannulated in one after 3 years. All six patients had difficulty with feeding, with weak suck and swallow necessitating nasogastric feeding in five, two of whom required gastrostomy. Despite all six children having had neonatal symptoms, the mean age at CMS diagnosis was 5 years and 9 months. CONCLUSION CMS, particularly caused by mutations in the DOK7 gene, is a rare but treatable cause of congenital stridor in the neonate. A combination of congenital stridor, especially with an apparently idiopathic bilateral vocal cord palsy and weak suck and swallow should alert the clinician to the possibility of CMS and prompt early referral for neurophysiology and genetic investigations. Confirmation of a CMS diagnosis enables treatment to be initiated, informed management of the VCP and anticipation of myasthenic symptoms, particularly life-threatening respiratory decompensation. Treatment may allow early decannulation or possible avoidance of tracheostomy. At least 12 genes are known to cause CMS; the presence of congenital stridor may help target genetic diagnosis.
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Affiliation(s)
- Chris G Jephson
- Department of Otolaryngology, Great Ormond Street Hospital for Children and Institute of Child Health, Great Ormond Street, London, WC1N 3JH, UK.
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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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Lashley D, Palace J, Jayawant S, Robb S, Beeson D. Ephedrine treatment in congenital myasthenic syndrome due to mutations in DOK7. Neurology 2010; 74:1517-23. [PMID: 20458068 DOI: 10.1212/wnl.0b013e3181dd43bf] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
BACKGROUND Mutations in the postsynaptic adaptor protein Dok-7 underlie congenital myasthenic syndrome (CMS) with a characteristic limb girdle pattern of muscle weakness. Patients usually do not respond to or worsen with the standard CMS treatments: cholinesterase inhibitors and 3,4-diaminopyridine. However, anecdotal reports suggest they may improve with ephedrine. METHODS This was an open prospective follow-up study to determine muscle strength in response to ephedrine in Dok-7 CMS. Patients were first evaluated as inpatients for suitability for a trial of treatment with ephedrine. The response was assessed at 2 and 6 to 8 months follow-up clinic visits using a quantitative myasthenia gravis (severity) score (QMG) and mobility measures. RESULTS Ten out of 12 of the cohort with DOK7 mutations tolerated ephedrine. We noted a progressive response to treatment over the 6 to 8 months assessment period with a significant improvement at the final QMG score (p = 0.009). Mobility scores also improved (p = 0.0006). Improvements in the subcomponents of the QMG score that measured proximal muscle function (those muscle groups most severely affected) were most marked, and in some cases were dramatic. All patients reported enhanced activities of daily living at 6-8 months. CONCLUSION Ephedrine appears to be an effective treatment for Dok-7 CMS. It is well-tolerated by most patients and improvement in strength can be profound. Determining the long-term response and the most effective dosing regimen will require further research. CLASSIFICATION OF EVIDENCE This study provides Class IV evidence that ephedrine given at doses between 15 and 90 mg/day improves muscle strength in patients with documented mutations in DOK7.
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Affiliation(s)
- D Lashley
- Weatherall Institute of Molecular Medicine, The John Radcliffe, Oxford OX3 9DS, UK
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Maselli RA, Arredondo J, Cagney O, Ng JJ, Anderson JA, Williams C, Gerke BJ, Soliven B, Wollmann RL. Mutations in MUSK causing congenital myasthenic syndrome impair MuSK-Dok-7 interaction. Hum Mol Genet 2010; 19:2370-9. [PMID: 20371544 PMCID: PMC2876883 DOI: 10.1093/hmg/ddq110] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
We describe a severe congenital myasthenic syndrome (CMS) caused by two missense mutations in the gene encoding the muscle specific receptor tyrosine kinase (MUSK). The identified MUSK mutations M605I and A727V are both located in the kinase domain of MuSK. Intracellular microelectrode recordings and microscopy studies of the neuromuscular junction conducted in an anconeus muscle biopsy revealed decreased miniature endplate potential amplitudes, reduced endplate size and simplification of secondary synaptic folds, which were consistent with postsynaptic deficit. The study also showed a striking reduction of the endplate potential quantal content, consistent with additional presynaptic failure. Expression studies in MuSK deficient myotubes revealed that A727V, which is located within the catalytic loop of the enzyme, caused severe impairment of agrin-dependent MuSK phosphorylation, aggregation of acetylcholine receptors (AChRs) and interaction of MuSK with Dok-7, an essential intracellular binding protein of MuSK. In contrast, M605I, resulted in only moderate impairment of agrin-dependent MuSK phosphorylation, aggregation of AChRs and interaction of MuSK with Dok-7. There was no impairment of interaction of mutants with either the low-density lipoprotein receptor-related protein, Lrp4 (a co-receptor of agrin) or with the mammalian homolog of the Drosophila tumorous imaginal discs (Tid1). Our findings demonstrate that missense mutations in MUSK can result in a severe form of CMS and indicate that the inability of MuSK mutants to interact with Dok-7, but not with Lrp4 or Tid1, is a major determinant of the pathogenesis of the CMS caused by MUSK mutations.
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Affiliation(s)
- Ricardo A Maselli
- Department of Neurology, School of Veterinary Medicine, University of California Davis, Davis, CA 95618, USA.
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Müller JS, Jepson CD, Laval SH, Bushby K, Straub V, Lochmüller H. Dok-7 promotes slow muscle integrity as well as neuromuscular junction formation in a zebrafish model of congenital myasthenic syndromes. Hum Mol Genet 2010; 19:1726-40. [PMID: 20147321 DOI: 10.1093/hmg/ddq049] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The small signalling adaptor protein Dok-7 has recently been reported as an essential protein of the neuromuscular junction (NMJ). Mutations resulting in partial loss of Dok-7 activity cause a distinct limb-girdle subtype of the inherited NMJ disorder congenital myasthenic syndromes (CMSs), whereas complete loss of Dok-7 results in a lethal phenotype in both mice and humans. Here we describe the zebrafish orthologue of Dok-7 and study its in vivo function. Dok-7 deficiency leads to motility defects in zebrafish embryos and larvae. The relative importance of Dok-7 at different stages of NMJ development varies; it is crucial for the earliest step, the formation of acetylcholine receptor (AChR) clusters in the middle of the muscle fibre prior to motor neuron contact. At later stages, presence of Dok-7 is not absolutely essential, as focal and non-focal synapses do form when Dok-7 expression is downregulated. These contacts however are smaller than in the wild-type zebrafish, reminiscent of the neuromuscular endplate pathology seen in patients with DOK7 mutations. Intriguingly, we also observed changes in slow muscle fibre arrangement; previously, Dok-7 has not been linked to functions other than postsynaptic AChR clustering. Our results suggest an additional role of Dok-7 in muscle. This role seems to be independent of the muscle-specific tyrosine kinase MuSK, the known binding partner of Dok-7 at the NMJ. Our findings in the zebrafish model contribute to a better understanding of the signalling pathways at the NMJ and the pathomechanisms of DOK7 CMSs.
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Affiliation(s)
- Juliane S Müller
- Institute of Human Genetics, International Centre for Life, Newcastle University, Central Parkway, Newcastle Upon Tyne NE1 3BZ, UK.
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Abstract
CollagenQ (ColQ) plays an important structural role at vertebrate neuromuscular junctions (NMJs) by anchoring and accumulating acetylcholinesterase (AChE) in the extracellular matrix (ECM). Moreover, ColQ interacts with perlecan/dystroglycan and the muscle-specific receptor tyrosine kinase (MuSK), key molecules in the NMJ formation. MuSK promotes acetylcholine receptor (AChR) clustering in a process mediated by rapsyn, a cytoplasmic protein that stimulates AChR packing in clusters and regulates synaptic gene transcription. Here, we investigated a regulatory role for ColQ by comparing the clustering and expression of synaptic proteins in wild type and ColQ-deficient muscle cells in culture and at NMJ. We show first that AChR clusters are smaller and more densely packed in the absence of ColQ both in vitro and in vivo. Second, we find that like AChRs and rapsyn, MuSK mRNA levels are increased in cultured cells but not in muscles lacking ColQ. However, membrane-bound MuSK is decreased both in vitro and in vivo suggesting that ColQ controls MuSK sorting or stabilization in the muscle membrane. In line with this, our data show that activation of the MuSK signaling pathway is altered in the absence of ColQ leading to (1) perturbation of AChR clustering and/or beta-AChR subunit phosphorylation and (2) modifications of AChR mRNA level due to the lack of ColQ-MuSK interaction. Together, our results demonstrate that ColQ, in addition to its structural role, has important regulatory functions at the synapse by controlling AChR clustering and synaptic gene expression through its interaction with MuSK.
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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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Schara U, Barisic N, Deschauer M, Lindberg C, Straub V, Strigl-Pill N, Wendt M, Abicht A, Müller J, Lochmüller H. Ephedrine therapy in eight patients with congenital myasthenic syndrome due to DOK7 mutations. Neuromuscul Disord 2009; 19:828-32. [DOI: 10.1016/j.nmd.2009.09.008] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2009] [Accepted: 09/21/2009] [Indexed: 10/20/2022]
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Maselli RA, Ng JJ, Anderson JA, Cagney O, Arredondo J, Williams C, Wessel HB, Abdel-Hamid H, Wollmann RL. Mutations in LAMB2 causing a severe form of synaptic congenital myasthenic syndrome. J Med Genet 2009; 46:203-8. [PMID: 19251977 PMCID: PMC2643050 DOI: 10.1136/jmg.2008.063693] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Background: We describe a severe form of congenital myasthenic syndrome (CMS) associated with congenital nephrosis and ocular malformations caused by two truncating mutations in the gene encoding the laminin β2 subunit (LAMB2). Methods and results: Mutational analysis in the affected patient, who has a history of a serious untoward reaction to treatment with acetylcholinesterase inhibition, revealed two frame-shifting heteroallelic mutations, a maternally inherited 1478delG and a paternally inherited 4804delC. An anconeus muscle biopsy demonstrated a profound distortion of the architecture and function of the neuromuscular junction, which was strikingly similar to that seen in mice lacking laminin β2 subunit. The findings included: pronounced reduction of the axon terminal size with encasement of the nerve endings by Schwann cells, severe widening of the primary synaptic cleft and invasion of the synaptic space by the processes of Schwann cells, and moderate simplification of postsynaptic folds and intact expression of the endplate acetylcholinesterase. The endplate potential quantal content was notably reduced, while the frequencies and amplitudes of miniature endplate potentials were only moderately diminished and the decay phases of miniature endplate potentials were normal. Western blot analysis of muscle and kidney tissue and immunohistochemistry of kidney tissue showed no laminin β2 expression. Conclusion: This case, which represents a new type of synaptic CMS, exemplifies the wide variability of phenotypes associated with LAMB2 mutations and underscores the fundamental role that laminin β2 plays in the development of the human neuromuscular junction.
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Affiliation(s)
- R A Maselli
- Department of Neurology, University of California Davis, Davis, CA, 95618, USA.
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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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Chevessier F, Girard E, Molgo J, Bartling S, Koenig J, Hantai D, Witzemann V. A mouse model for congenital myasthenic syndrome due to MuSK mutations reveals defects in structure and function of neuromuscular junctions. Hum Mol Genet 2008; 17:3577-95. [DOI: 10.1093/hmg/ddn251] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Heuss D, Klascinski J, Schubert SW, Moriabadi T, Lochmüller H, Hashemolhosseini S. Examination of transcript amounts and activity of protein kinase CK2 in muscle lysates of different types of human muscle pathologies. Mol Cell Biochem 2008; 316:135-40. [PMID: 18553059 DOI: 10.1007/s11010-008-9819-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2008] [Accepted: 05/29/2008] [Indexed: 10/22/2022]
Abstract
Motoneurons release the heparansulfate proteoglycan agrin and thereby activate the muscle-specific receptor tyrosine kinase (MuSK), which is the main organizer of subsynaptic specializations at the neuromuscular junction. Recently, we showed that (1) the protein kinase CK2 interacts with the intracellular region of MuSK; (2) the CK2 protein is enriched and co-localized with MuSK at postsynaptic specializations; (3) CK2-mediated phosphorylation of serine residues within a specific MuSK epitope, named the kinase insert, regulates acetylcholine receptor (AChR) clustering; (4) muscle-specific CK2beta knockout mice develop a myasthenic phenotype due to impaired muscle endplate structure and function (see Genes Dev 20(13):1800-1816, 2006). Here, we investigated for the first time if CK2 is modulated in biopsies from human patients. To this end, we measured transcript amounts of the subunits CK2alpha and CK2beta and determined holoenzyme CK2 activity in 34 muscle biopsies of human patients with different muscle pathologies.
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Affiliation(s)
- Dieter Heuss
- Neurologische Klinik, Universität Erlangen-Nürnberg, Schwabachanlage 6, 91054, Erlangen, Germany
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