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Hesami O, Ramezani M, Ghasemi A, Fatehi F, Okhovat AA, Ziaadini B, Kariminejad A, Nafissi S. COLQ-Congenital myasthenic syndrome in an Iranian cohort: the clinical and genetics spectrum. Orphanet J Rare Dis 2024; 19:113. [PMID: 38475910 DOI: 10.1186/s13023-024-03116-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Accepted: 03/03/2024] [Indexed: 03/14/2024] Open
Abstract
BACKGROUND Congenital myasthenic syndrome (CMS) is a group of neuromuscular disorders caused by abnormal signal transmission at the motor endplate. Mutations in the collagen-like tail subunit gene (COLQ) of acetylcholinesterase are responsible for recessive forms of synaptic congenital myasthenic syndromes with end plate acetylcholinesterase deficiency. Clinical presentation includes ptosis, ophthalmoparesis, and progressive weakness with onset at birth or early infancy. METHODS We followed 26 patients with COLQ-CMS over a mean period of 9 years (ranging from 3 to 213 months) and reported their clinical features, electrophysiologic findings, genetic characteristics, and therapeutic management. RESULTS In our population, the onset of symptoms ranged from birth to 15 years. Delayed developmental motor milestones were detected in 13 patients (∼ 52%), and the most common presenting signs were ptosis, ophthalmoparesis, and limb weakness. Sluggish pupils were seen in 8 (∼ 30%) patients. All patients who underwent electrophysiologic study showed a significant decremental response (> 10%) following low-frequency repetitive nerve stimulation. Moreover, double compound muscle action potential was evident in 18 patients (∼ 75%). We detected 14 variants (eight novel variants), including six missense, three frameshift, three nonsense, one synonymous and one copy number variation (CNV), in the COLQ gene. There was no benefit from esterase inhibitor treatment, while treatment with ephedrine and salbutamol was objectively efficient in all cases. CONCLUSION Despite the rarity of the disease, our findings provide valuable information for understanding the clinical and electrophysiological features as well as the genetic characterization and response to the treatment of COLQ-CMS.
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Affiliation(s)
- Omid Hesami
- Neuromuscular Research Center, Tehran University of Medical Sciences, Tehran, Iran
- Neurology Department, Imam Hossein Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Mahtab Ramezani
- Neuromuscular Research Center, Tehran University of Medical Sciences, Tehran, Iran
- Neurology Department, Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran
| | - Aida Ghasemi
- Neuromuscular Research Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Farzad Fatehi
- Neuromuscular Research Center, Tehran University of Medical Sciences, Tehran, Iran
- Neurology Department, Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran
| | - Ali Asghar Okhovat
- Neuromuscular Research Center, Tehran University of Medical Sciences, Tehran, Iran
- Neurology Department, Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran
| | - Bentolhoda Ziaadini
- Neurology Research Center, Kerman University of Medical Sciences, Kerman, Iran
| | | | - Shahriar Nafissi
- Neuromuscular Research Center, Tehran University of Medical Sciences, Tehran, Iran.
- Neurology Department, Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran.
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Kediha MI, Tazir M, Magnouche C, Sternberg D, Belarbi S, Eymard B, Ali Pacha L. Congenital myasthenic syndrome by mutation of the ColQ gene: Phenotypic and evolutionary profile of three Algerian families. Rev Neurol (Paris) 2023:S0035-3787(23)00754-3. [PMID: 36764859 DOI: 10.1016/j.neurol.2022.09.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 09/24/2022] [Accepted: 09/29/2022] [Indexed: 02/10/2023]
Abstract
BACKGROUND Congenital myasthenic syndromes (CMS) are rare genetic neuromuscular disorders. The COLQ gene encoding the collagenous subunit of the acetyl cholinesterase enzyme tail is implicated in a synaptic form of CMS (also called type 5, according to the new gene table 2020 classification). OBJECTIVE To study the clinical phenotype of three families with COLQ gene mutations. METHODS We report a series of three consanguineous families, with seven affected patients, carrying three different mutations of the COLQ gene, one of which has never been reported in the literature before. RESULTS We studied their clinical and paraclinical phenotypes, and try to compare the three families as well as compare them with other series carrying COLQ gene mutations reported in the literature. CONCLUSION COLQ gene mutations have phenotypic particularities that must be recognized to propose appropriate genetic study.
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Affiliation(s)
- M I Kediha
- Neurology department, Mustapha Bacha university Hospital, Algiers, Algeria.
| | - M Tazir
- Neurology department, Mustapha Bacha university Hospital, Algiers, Algeria
| | - C Magnouche
- Neurology department, Ali Ait Idir university Hospital, Algiers, Algeria
| | - D Sternberg
- Myogenetics laboratory, Pitié Salpetriere university hospital, Paris, France
| | - S Belarbi
- Neurology department, Ali Ait Idir university Hospital, Algiers, Algeria
| | - B Eymard
- Neurology department, Pitié Saleptriere university hospital, Paris, France
| | - L Ali Pacha
- Neurology department, Mustapha Bacha university Hospital, Algiers, Algeria
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3
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Treatment and Management of Disorders of the Neuromuscular Junction. Neuromuscul Disord 2022. [DOI: 10.1016/b978-0-323-71317-7.00019-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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4
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Mayse ML, Norman HS, Peterson AD, Rouw KT, Johnson PJ. Targeted lung denervation in sheep: durability of denervation and long-term histologic effects on bronchial wall and peribronchial structures. Respir Res 2020; 21:117. [PMID: 32423414 PMCID: PMC7236341 DOI: 10.1186/s12931-020-01383-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2019] [Accepted: 05/04/2020] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Targeted lung denervation (TLD), a novel bronchoscopic procedure which attenuates pulmonary nerve input to the lung to reduce the clinical consequences of neural hyperactivity, may be an important emerging treatment for COPD. While procedural safety and impact on clinical outcomes have recently been reported, the mechanism of action has not been reported. We explored the long-term pathologic and histopathologic effects in a sheep model of ablation of bronchial branches of the vagus nerve using a novel dual-cooled radiofrequency ablation catheter. METHODS Nineteen sheep underwent circumferential ablation of both main bronchi with simultaneous balloon surface cooling using a targeted lung denervation system (Nuvaira, Inc., USA). Animals were followed over an extended time course (30, 365, and 640 days post procedure). At each time point, lung denervation (axonal staining in bronchial nerves), and effect on peribronchial structures near the treatment site (histopathology of bronchial epithelium, bronchial cartilage, smooth muscle, alveolar parenchyma, and esophagus) were quantified. One way analysis of variance (ANOVA) was performed to reveal differences between group means on normal data. Non-parametric analysis using Kruskal-Wallis Test was employed on non-normal data sets. RESULTS No adverse clinical effects were observed in any sheep. Nerve axon staining distal to the ablation site was decreased by 60% at 30 days after TLD and efferent axon staining was decreased by >70% at 365 and 640 days. All treated airways exhibited 100% epithelial integrity. Effect on peribronchial structures was strictly limited to lung tissue immediately adjacent to the ablation site. Tissue structure 1 cm proximal and distal to the treatment area remained normal, and the pulmonary veins, pulmonary arteries, and esophagus were unaffected. CONCLUSIONS The denervation of efferent axons induced by TLD therapy is durable and likely a contributing mechanism through which targeted lung denervation impacts clinical outcomes. Further, long term lung denervation did not alter the anatomy of the bronchioles or lung, as evaluated from both a gross and histologic perspective.
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Affiliation(s)
- Martin L Mayse
- Nuvaira, Inc, Suite 105 3750 Annapolis Lane North, Minneapolis, MN, 55447, USA
| | - Holly S Norman
- Nuvaira, Inc, Suite 105 3750 Annapolis Lane North, Minneapolis, MN, 55447, USA
| | | | - Kristina T Rouw
- Nuvaira, Inc, Suite 105 3750 Annapolis Lane North, Minneapolis, MN, 55447, USA
| | - Philip J Johnson
- Nuvaira, Inc, Suite 105 3750 Annapolis Lane North, Minneapolis, MN, 55447, USA.
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5
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Xing G, Jing H, Zhang L, Cao Y, Li L, Zhao K, Dong Z, Chen W, Wang H, Cao R, Xiong WC, Mei L. A mechanism in agrin signaling revealed by a prevalent Rapsyn mutation in congenital myasthenic syndrome. eLife 2019; 8:e49180. [PMID: 31549961 PMCID: PMC6779466 DOI: 10.7554/elife.49180] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2019] [Accepted: 09/23/2019] [Indexed: 12/15/2022] Open
Abstract
Neuromuscular junction is a synapse between motoneurons and skeletal muscles, where acetylcholine receptors (AChRs) are concentrated to control muscle contraction. Studies of this synapse have contributed to our understanding of synapse assembly and pathological mechanisms of neuromuscular disorders. Nevertheless, underlying mechanisms of NMJ formation was not well understood. To this end, we took a novel approach - studying mutant genes implicated in congenital myasthenic syndrome (CMS). We showed that knock-in mice carrying N88K, a prevalent CMS mutation of Rapsyn (Rapsn), died soon after birth with profound NMJ deficits. Rapsn is an adapter protein that bridges AChRs to the cytoskeleton and possesses E3 ligase activity. In investigating how N88K impairs the NMJ, we uncovered a novel signaling pathway by which Agrin-LRP4-MuSK induces tyrosine phosphorylation of Rapsn, which is required for its self-association and E3 ligase activity. Our results also provide insight into pathological mechanisms of CMS.
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Affiliation(s)
- Guanglin Xing
- Department of Neurosciences, School of MedicineCase Western Reserve UniversityClevelandUnited States
| | - Hongyang Jing
- Department of Neurosciences, School of MedicineCase Western Reserve UniversityClevelandUnited States
| | - Lei Zhang
- Department of Neurosciences, School of MedicineCase Western Reserve UniversityClevelandUnited States
| | - Yu Cao
- Department of Neuroscience and Regenerative MedicineAugusta UniversityAugustaUnited States
| | - Lei Li
- Department of Neurosciences, School of MedicineCase Western Reserve UniversityClevelandUnited States
| | - Kai Zhao
- Department of Neurosciences, School of MedicineCase Western Reserve UniversityClevelandUnited States
- Department of Neuroscience and Regenerative MedicineAugusta UniversityAugustaUnited States
| | - Zhaoqi Dong
- Department of Neurosciences, School of MedicineCase Western Reserve UniversityClevelandUnited States
| | - Wenbing Chen
- Department of Neurosciences, School of MedicineCase Western Reserve UniversityClevelandUnited States
| | - Hongsheng Wang
- Department of Neurosciences, School of MedicineCase Western Reserve UniversityClevelandUnited States
| | - Rangjuan Cao
- Department of Neurosciences, School of MedicineCase Western Reserve UniversityClevelandUnited States
| | - Wen-Cheng Xiong
- Department of Neurosciences, School of MedicineCase Western Reserve UniversityClevelandUnited States
- Louis Stokes Cleveland Veterans Affairs Medical CenterClevelandUnited States
| | - Lin Mei
- Department of Neurosciences, School of MedicineCase Western Reserve UniversityClevelandUnited States
- Louis Stokes Cleveland Veterans Affairs Medical CenterClevelandUnited States
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6
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Clausen L, Cossins J, Beeson D. Beta-2 Adrenergic Receptor Agonists Enhance AChR Clustering in C2C12 Myotubes: Implications for Therapy of Myasthenic Disorders. J Neuromuscul Dis 2018; 5:231-240. [PMID: 29865088 PMCID: PMC6004912 DOI: 10.3233/jnd-170293] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Background: Congenital myasthenic syndromes (CMS) are a group of inherited neuromuscular transmission disorders causing fatiguable muscle weakness. ADRB2 agonists have been observed to provide therapeutic benefit where destabilisation of NMJ structures is part of the underlying pathology, such as in DOK7, COLQ and MuSK CMS as well as in slow channel syndrome. However, very little is known about the molecular mechanisms underlying the effects of ADRB2 agonists in CMS. Objective: In vitro investigation into whether an ADRB2 agonist affects the AChR clustering pathway and has the potential to increase the number and stability of AChR clusters. Methods: Cultured C2C12 mouse myotubes overexpressing the common DOK7 frameshift mutation c.1124_1127dupTGCC were incubated with salbutamol sulphate and the effect on AChR cluster numbers were investigated. Moreover, agrin-induced AChR clusters in C2C12 WT cells were left to disperse after agrin-wash-off, and the effects of incubation with salbutamol sulphate on AChR cluster numbers were explored. Results: Salbutamol sulphate induced a significant increase in the number of AChR clusters formed on C2C12 cells overexpressing c.1124_1127dupTGCC. Furthermore, significantly more clusters remained in C2C12 WT myotubes incubated with salbutamol sulphate following agrin wash-off. Conclusions: The results suggest that ADRB2 agonists directly affect proteins located at the neuromuscular junction and exert a stabilising effect on AChR clusters.
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Affiliation(s)
- Lisa Clausen
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Headley Way, Oxford, UK
| | - Judith Cossins
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Headley Way, Oxford, UK
| | - David Beeson
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Headley Way, Oxford, UK
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Wan Y, Yuan G, He B, Xu B, Xie W, Wang S, Zhang Y, Wu Q, Zhou X. Foccα6, a truncated nAChR subunit, positively correlates with spinosad resistance in the western flower thrips, Frankliniella occidentalis (Pergande). INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2018; 99:1-10. [PMID: 29753712 DOI: 10.1016/j.ibmb.2018.05.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Revised: 02/07/2018] [Accepted: 05/07/2018] [Indexed: 06/08/2023]
Abstract
Nicotinic acetylcholine receptors (nAChRs), a molecular target for spinosyns and neonicotinoids, mediate rapid cholinergic transmission in insect central nervous system by binding acetylcholine. Previous studies have shown that mutations in nAChRs contribute to the high level of resistance to these two classes of insecticides. In this study, we identified nine nAChR subunits from a transcriptome of the western flower thrips, Frankliniella occidentalis, including α1-7, β1, and β2. Exon 4 of α4 and exons 3 and 8 of α6 each have two splicing variants, respectively. In addition, altered or incorrect splicing leads to truncated forms of α3, α5, and α6 subunits. The abundance of every nAChRs in both spinosad susceptible and resistant strains was highest in the 1st instar nymph. Significantly more truncated forms of α6 subunit were detected in spinosad resistant strains, whereas, hardly any full-length form was found in the two highly resistant F. occidentalis strains (resistance ratio >104-fold). Under laboratory conditions, spinosad resistance was positively correlated with truncated α6 transcripts. The correlation was later confirmed under the field conditions using five field strains. As the molecular target of spinosad, the percentage of truncated nAChR α6 subunits can be used as a diagnostic tool to detect and quantify spinosad resistance in the field.
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Affiliation(s)
- Yanran Wan
- Department of Plant Protection, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.
| | - Guangdi Yuan
- Department of Plant Protection, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.
| | - Bingqing He
- Department of Plant Protection, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.
| | - Baoyun Xu
- Department of Plant Protection, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.
| | - Wen Xie
- Department of Plant Protection, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.
| | - Shaoli Wang
- Department of Plant Protection, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.
| | - Youjun Zhang
- Department of Plant Protection, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.
| | - Qingjun Wu
- Department of Plant Protection, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.
| | - Xuguo Zhou
- Department of Entomology, University of Kentucky, Lexington, KY, USA.
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8
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Lorenzoni PJ, Scola RH, Kay CSK, Werneck LC, Horvath R, Lochmüller H. How to Spot Congenital Myasthenic Syndromes Resembling the Lambert–Eaton Myasthenic Syndrome? A Brief Review of Clinical, Electrophysiological, and Genetics Features. Neuromolecular Med 2018; 20:205-214. [DOI: 10.1007/s12017-018-8490-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Accepted: 04/16/2018] [Indexed: 01/26/2023]
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9
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Ding Q, Shen D, Dai Y, Hu Y, Guan Y, Liu M, Cui L. Mechanism hypotheses for the electrophysiological manifestations of two cases of endplate acetylcholinesterase deficiency related congenital myasthenic syndrome. J Clin Neurosci 2017; 48:229-232. [PMID: 29150079 DOI: 10.1016/j.jocn.2017.10.084] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Accepted: 10/23/2017] [Indexed: 11/16/2022]
Abstract
OBJECTIVE To summarize the electrophysiological characteristics of two cases of endplate acetylcholinesterase deficiency (EAD) related congenital myasthenic syndrome (CMS) caused by COLQ mutation and to discuss the possible mechanism of these electrophysiological phenomena. METHODS Electrophysiological examinations were conducted including nerve conduction studies, routine electromyography (EMG), repetitive nerve stimulation (RNS) and single fiber EMG (SFEMG). The ulnar nerve was also stimulated at 50 Hz followed by 0.5 Hz to record the recovery process of compound muscle action potential (CMAP). RESULTS Repetitive CMAP (R-CMAP) was found in motor nerve conduction in both cases. Needle EMG showed myogenic damages and SFEMG showed remarkably increased jitter values. Of note, the amplitude of CMAP and R-CMAP showed regular changing trends, and so did their time intervals in RNS studies. CONCLUSIONS The change patterns of CMAP and R-CMAP, in combination with other electrophysiological features are very useful for the diagnosis of EAD related CMS, especially in predicting the presence of correct gene mutations.
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Affiliation(s)
- Qingyun Ding
- Department of Neurology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing 100730, China.
| | - Dongchao Shen
- Department of Neurology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing 100730, China.
| | - Yi Dai
- Department of Neurology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing 100730, China.
| | - Youfang Hu
- Department of Neurology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing 100730, China.
| | - Yuzhou Guan
- Department of Neurology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing 100730, China.
| | - Mingsheng Liu
- Department of Neurology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing 100730, China; Neuroscience Center, Chinese Academy of Medical Sciences, Beijing 100730, China.
| | - Liying Cui
- Department of Neurology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing 100730, China; Neuroscience Center, Chinese Academy of Medical Sciences, Beijing 100730, China.
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10
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Al-Muhaizea MA, Al-Mobarak SB. COLQ-mutant Congenital Myasthenic Syndrome with Microcephaly: A Unique Case with Literature Review. Transl Neurosci 2017; 8:65-69. [PMID: 28744372 PMCID: PMC5518714 DOI: 10.1515/tnsci-2017-0011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Accepted: 05/15/2017] [Indexed: 11/15/2022] Open
Abstract
Congenital Myasthenic Syndrome (CMS) is a group of inherited neuromuscular junction disorders caused by defects in several genes. Clinical features include delayed motor milestones, recurrent respiratory illnesses and variable fatigable weakness. The central nervous system involvement is typically not part of the CMS. We report here a Saudi girl with genetically proven Collagen Like Tail Subunit Of Asymmetric Acetylcholinesterase (COLQ) mutation type CMS who has global developmental delay, microcephaly and respiratory failure. We have reviewed the literature regarding COLQ-type CMS and to the best of our knowledge this is the first ever reported association of congenital myasthenia syndrome with microcephaly.
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11
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Yiş U, Becker K, Kurul SH, Uyanik G, Bayram E, Haliloğlu G, Polat Aİ, Ayanoğlu M, Okur D, Tosun AF, Serdaroğlu G, Yilmaz S, Topaloğlu H, Anlar B, Cirak S, Engel AG. Genetic Landscape of Congenital Myasthenic Syndromes From Turkey: Novel Mutations and Clinical Insights. J Child Neurol 2017; 32:759-765. [PMID: 28464723 PMCID: PMC5655993 DOI: 10.1177/0883073817705252] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Congenital myasthenic syndromes are clinically and genetically heterogeneous disorders of neuromuscular transmission. Most are treatable, but certain subtypes worsen with cholinesterase inhibitors. This underlines the importance of genetic diagnosis. Here, the authors report on cases with genetically proven congenital myasthenic syndromes from Turkey. The authors retrospectively reviewed their experience of all patients with congenital myasthenic syndromes, referred over a 5-year period (2011-2016) to the Child Neurology Department of Dokuz Eylül University, Izmir, Turkey. In addition, PubMed was searched for published cases of genetically proven congenital myasthenic syndromes originating from Turkey. In total, the authors identified 43 (8 new patients, 35 recently published patients) cases. Defects in the acetylcholine receptor (n = 15; 35%) were the most common type, followed by synaptic basal-lamina associated (n = 14; 33%) and presynaptic syndromes (n = 10; 23%). The authors had only 3 cases (7%) who had defects in endplate development. One patient had mutation GFPT1 gene (n = 1; 2%). Knowledge on congenital myasthenic syndromes and related genes in Turkey will lead to prompt diagnosis and treatment of these rare neuromuscular disorders.
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Affiliation(s)
- Uluç Yiş
- Dokuz Eylül University, School of Medicine, Department of Pediatrics, Division of Child Neurology, İzmir, TURKEY
| | - Kerstin Becker
- Cologne University, Department of Pediatrics, Center for Molecular Medicine Cologne, Cologne, GERMANY
| | - Semra Hız Kurul
- Dokuz Eylül University, School of Medicine, Department of Pediatrics, Division of Child Neurology, İzmir, TURKEY
| | - Gökhan Uyanik
- Center for Medical Genetics, Hanusch Hospital, Vienna, AUSTRIA
- Medical Faculty, Sigmund Freud University, Vienna, AUSTRIA
| | - Erhan Bayram
- Dokuz Eylül University, School of Medicine, Department of Pediatrics, Division of Child Neurology, İzmir, TURKEY
| | - Göknur Haliloğlu
- Hacettepe University, School of Medicine, Department of Pediatrics, Division of Child Neurology, Ankara, TURKEY
| | - Ayşe İpek Polat
- Dokuz Eylül University, School of Medicine, Department of Pediatrics, Division of Child Neurology, İzmir, TURKEY
| | - Müge Ayanoğlu
- Dokuz Eylül University, School of Medicine, Department of Pediatrics, Division of Child Neurology, İzmir, TURKEY
| | - Derya Okur
- Dokuz Eylül University, School of Medicine, Department of Pediatrics, Division of Child Neurology, İzmir, TURKEY
| | - Ayşe Fahriye Tosun
- Adnan Menderes University, School of Medicine, Department of Pediatrics, Division of Child Neurology, Aydın, TURKEY
| | - Gül Serdaroğlu
- Ege University, School of Medicine, Department of Pediatrics, Division of Child Neurology, İzmir, TURKEY
| | - Sanem Yilmaz
- Ege University, School of Medicine, Department of Pediatrics, Division of Child Neurology, İzmir, TURKEY
| | - Haluk Topaloğlu
- Hacettepe University, School of Medicine, Department of Pediatrics, Division of Child Neurology, Ankara, TURKEY
| | - Banu Anlar
- Hacettepe University, School of Medicine, Department of Pediatrics, Division of Child Neurology, Ankara, TURKEY
| | - Sebahattin Cirak
- Cologne University, Department of Pediatrics, Center for Molecular Medicine Cologne, Cologne, GERMANY
| | - Andrew G. Engel
- Mayo Clinic, Rochester, Department of Neurology, MN 55905, USA
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12
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Alam MS, Devi Nivean P. Early onset bilateral juvenile myasthenia gravis masquerading as simple congenital ptosis. GMS OPHTHALMOLOGY CASES 2017; 7:Doc07. [PMID: 28293536 PMCID: PMC5343208 DOI: 10.3205/oc000058] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Myasthenia gravis is an autoimmune disorder affecting the neuromuscular junction. Ocular myasthenia gravis presents as ptosis with extraocular motility restriction and is prone to be misdiagnosed as third nerve palsy or congenital or aponeurotic ptosis. Juvenile ocular myasthenia gravis in very young children is difficult to diagnose and can be easily labeled as a case of congenital ptosis, the more so when the condition is bilateral. We present a case of a two-year-old child who presented with bilateral ptosis and was diagnosed as a case of simple congenital ptosis elsewhere with the advice to undergo tarsofrontalis sling surgery. The child was diagnosed with juvenile myasthenia gravis on thorough history, examination, and systemic evaluation and was started on anti-myasthenic treatment.
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Affiliation(s)
- Md Shahid Alam
- Department of Orbit, Oculoplasty, Reconstructive and Aesthetic services, Sankara Nethralaya, Medical Research Foundation, Chennai, Tamil Nadu, India
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13
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van den Engel-Hoek L, de Groot IJM, de Swart BJM, Erasmus CE. Feeding and Swallowing Disorders in Pediatric Neuromuscular Diseases: An Overview. J Neuromuscul Dis 2015; 2:357-369. [PMID: 27858755 PMCID: PMC5240596 DOI: 10.3233/jnd-150122] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Feeding and swallowing problems in infants and children have a great impact on health and wellbeing. The aim of this study was to provide an overview of recognized feeding and swallowing problems in different groups of children with neuromuscular diseases, based on relevant literature and expert opinion, and to propose recommendations for the assessment and treatment of these problems. Almost all pediatric neuromuscular diseases are accompanied by feeding and swallowing problems during the different phases of deglutition, problems that give rise to a wide variety of signs and symptoms, which emphasizes the importance of a comprehensive feeding and swallowing assessment by a speech and language therapist.
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Affiliation(s)
- Lenie van den Engel-Hoek
- Donders Centre for Neuroscience, Department of Rehabilitation, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Imelda J M de Groot
- Donders Centre for Neuroscience, Department of Rehabilitation, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Bert J M de Swart
- Donders Centre for Neuroscience, Department of Rehabilitation, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Corrie E Erasmus
- Donders Centre for Neuroscience, Department of Neurology, Radboud University Medical Center, Nijmegen, The Netherlands
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Gandolfi B, Grahn RA, Creighton EK, Williams DC, Dickinson PJ, Sturges BK, Guo LT, Shelton GD, Leegwater PAJ, Longeri M, Malik R, Lyons LA. COLQ variant associated with Devon Rex and Sphynx feline hereditary myopathy. Anim Genet 2015; 46:711-5. [PMID: 26374066 PMCID: PMC4637250 DOI: 10.1111/age.12350] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/30/2015] [Indexed: 01/26/2023]
Abstract
Some Devon Rex and Sphynx cats have a variably progressive myopathy characterized by appendicular and axial muscle weakness, megaesophagus, pharyngeal weakness and fatigability with exercise. Muscle biopsies from affected cats demonstrated variable pathological changes ranging from dystrophic features to minimal abnormalities. Affected cats have exacerbation of weakness following anticholinesterase dosing, a clue that there is an underlying congenital myasthenic syndrome (CMS). A genome-wide association study and whole-genome sequencing suggested a causal variant for this entity was a c.1190G>A variant causing a cysteine to tyrosine substitution (p.Cys397Tyr) within the C-terminal domain of collagen-like tail subunit (single strand of homotrimer) of asymmetric acetylcholinesterase (COLQ). Alpha-dystroglycan expression, which is associated with COLQ anchorage at the motor end-plate, has been shown to be deficient in affected cats. Eighteen affected cats were identified by genotyping, including cats from the original clinical descriptions in 1993 and subsequent publications. Eight Devon Rex and one Sphynx not associated with the study were identified as carriers, suggesting an allele frequency of ~2.0% in Devon Rex. Over 350 tested cats from other breeds did not have the variant. Characteristic clinical features and variant presence in all affected cats suggest a model for COLQ CMS. The association between the COLQ variant and this CMS affords clinicians the opportunity to confirm diagnosis via genetic testing and permits owners and breeders to identify carriers in the population. Moreover, accurate diagnosis increases available therapeutic options for affected cats based on an understanding of the pathophysiology and experience from human CMS associated with COLQ variants.
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Affiliation(s)
- Barbara Gandolfi
- Department of Veterinary Medicine and Surgery, College of Veterinary Medicine, University of Missouri - Columbia, Columbia, MO, 65211, USA
| | - Robert A Grahn
- Veterinary Genetics Laboratory, School of Veterinary Medicine, University of California - Davis, Davis, CA, 95616, USA
| | - Erica K Creighton
- Department of Veterinary Medicine and Surgery, College of Veterinary Medicine, University of Missouri - Columbia, Columbia, MO, 65211, USA
| | - D Colette Williams
- The William R. Pritchard Veterinary Medical Teaching Hospital, School of Veterinary Medicine, University of California - Davis, Davis, CA, 95616, USA
| | - Peter J Dickinson
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California - Davis, Davis, CA, 95616, USA
| | - Beverly K Sturges
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California - Davis, Davis, CA, 95616, USA
| | - Ling T Guo
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California - Davis, Davis, CA, 95616, USA
| | - G Diane Shelton
- Department of Pathology, University of California - San Diego, La Jolla, CA, 92093, USA
| | - Peter A J Leegwater
- Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, Utrecht University, 3508 TD, Utrecht, The Netherlands
| | - Maria Longeri
- Dipartimento di Scienze Veterinarie e Sanità Pubblica, University of Milan, Milan, Italy
| | - Richard Malik
- Centre for Veterinary Education, University of Sydney, Sydney, NSW, 2006, Australia
| | - Leslie A Lyons
- Department of Veterinary Medicine and Surgery, College of Veterinary Medicine, University of Missouri - Columbia, Columbia, MO, 65211, USA
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Laparoscopic Sleeve Gastrectomy in a Morbidly Obese Patient with Myasthenia Gravis: A Review of the Management. Case Rep Med 2015; 2015:593586. [PMID: 26294914 PMCID: PMC4532903 DOI: 10.1155/2015/593586] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Accepted: 07/16/2015] [Indexed: 11/29/2022] Open
Abstract
Myasthenia gravis, a disorder of neuromuscular transmission, presents a unique challenge to the perioperative anesthetic management of morbidly obese patients. This report describes the case of a 27-year-old morbidly obese woman with a past medical history significant for myasthenia gravis and fatty liver disease undergoing bariatric surgery. Anesthesia was induced with intravenous agents and maintained with an inhalational and balanced intravenous technique. The nondepolarizing neuromuscular blocker Cisatracurium was chosen so that no reversal agents were given. Neostigmine was not used to antagonize the effects of Cisatracurium. The goal of this approach was to reduce the risk of complications such as postoperative mechanical ventilation. The anesthetic and surgical techniques used resulted in an uneventful hospital course. Therefore, we can minimize perioperative risks and complications by adjusting the anesthetic plan based on the patient's physiology and comorbidities as well as the pharmacology of the drugs.
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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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Das AS, Agamanolis DP, Cohen BH. Use of next-generation sequencing as a diagnostic tool for congenital myasthenic syndrome. Pediatr Neurol 2014; 51:717-20. [PMID: 25194721 DOI: 10.1016/j.pediatrneurol.2014.07.032] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Revised: 07/29/2014] [Accepted: 07/31/2014] [Indexed: 11/30/2022]
Abstract
BACKGROUND The clinical presentation of congenital myasthenic syndromes is similar to many other neuromuscular disorders of infancy, and with 12 known discrete genetic forms of congenital myasthenic syndromes, both the diagnosis and treatment decisions present clinical challenges. PATIENT DESCRIPTION We report a 20-month-old boy with rapsyn deficiency. At birth, he presented with a weak cry, hypotonia, joint contractures, and facial deformity. Because of respiratory difficulty associated with muscle fatigue, he spent a total of 71 days in the neonatal intensive care unit and 47 days in the pediatric intensive care unit. Imaging study results were normal, along with a battery of metabolic tests and electrodiagnostic studies. A limited genetic evaluation for reversible cytochrome c oxidase deficiency was negative, as was the oligonucleotide microarray. A muscle biopsy demonstrated myofiber atrophy in a pattern consistent with early denervation. Based on nonspecific and nondiagnostic results, whole-exome (next generation) sequencing was performed. This study identified two confirmed pathogenic mutations in the RAPSN gene that are associated with congenital myasthenic syndrome (OMIM 608931). The patient was treated with pyridostigmine at 16 months of age, which resulted in a dramatic improvement in muscle tone and strength and a steady resolution of joint contractures. Four months after treatment was initiated, he was beginning to bear weight and was able to sit unsupported and vocalize full words. CONCLUSIONS This patient serves to highlight next-generation sequencing as an important diagnostic tool that can result in life-saving treatment.
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Affiliation(s)
- Alvin S Das
- Northeast Ohio Medical University, Rootstown, Ohio
| | - Dimitri P Agamanolis
- Department of Pathology and Laboratory Medicine, Akron Children's Hospital, Akron, Ohio; Department of Pathology, Northeast Ohio Medical University, Rootstown, Ohio
| | - Bruce H Cohen
- Division of Neurology, NeuroDevelopmental Science Center, Akron Children's Hospital, Akron, Ohio; Department of Pediatrics, Northeast Ohio Medical University, Rootstown, Ohio.
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18
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Clinical and molecular analysis of a novel COLQ missense mutation causing congenital myasthenic syndrome in a Syrian family. Pediatr Neurol 2014; 51:165-9. [PMID: 24938146 DOI: 10.1016/j.pediatrneurol.2014.03.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/01/2014] [Revised: 03/12/2014] [Accepted: 03/15/2014] [Indexed: 02/08/2023]
Abstract
BACKGROUND Congenital myasthenic syndromes with end-plate acetylcholinesterase deficiency are rare autosomal recessive disorders characterized by onset of the disease in early childhood, general weakness exacerbated by exertion, ophthalmoplegia, and refractoriness to anticholinesterase drugs. To date, all reported cases have been attributed to mutations in 18 genes including the COLQ gene that encodes a specific collagen that anchors acetylcholinesterase at the basal lamina of the neuromuscular junction. We identified a Syrian family with two children of consanguineous parents from two branches affected with congenital myasthenic syndrome with end-plate acetylcholinesterase deficiency. METHOD The absence of acetylcholinesterase antibodies was demonstrated biochemically. Consequently, all the coding regions, exon-intron boundaries, and the 5' and 3' untranslated regions of the COLQ gene were amplified and sequenced using the Sanger sequencing method. RESULTS We observed that the severity of the phenotype in the two affected children differed. One child had mild symptoms that included difficulties in gait and feeding with mild respiratory insufficiency. Her sibling died in the first months of life because of severe respiratory failure. The second patient had severe symptoms from birth and has been mechanically ventilated. DNA sequencing revealed a novel homozygous single nucleotide substitution mutation (c.1010T>C) in the COLQ gene in both patients. This substitution leads to a missense amino acid substitution at position 337 of the protein (p.Ile337Thr). This mutation is likely to impair ColQ's trimeric organization and therefore its anchoring within the synaptic basal lamina. CONCLUSION We identified the molecular cause underlying congenital myasthenic syndrome in two patients. The marked phenotypic variation suggests that other factors including modifier genes may affect the severity of this disease.
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19
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Rudell JC, Borges LS, Rudell JB, Beck KA, Ferns MJ. Determinants in the β and δ subunit cytoplasmic loop regulate Golgi trafficking and surface expression of the muscle acetylcholine receptor. J Biol Chem 2013; 289:203-14. [PMID: 24240098 DOI: 10.1074/jbc.m113.502328] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
The molecular determinants that govern nicotinic acetylcholine receptor (AChR) assembly and trafficking are poorly defined, and those identified operate largely during initial receptor biogenesis in the endoplasmic reticulum. To identify determinants that regulate later trafficking steps, we performed an unbiased screen using chimeric proteins consisting of CD4 fused to the muscle AChR subunit cytoplasmic loops. In C2 mouse muscle cells, we found that CD4-β and δ subunit loops were expressed at very low levels on the cell surface, whereas the other subunit loops were robustly expressed on the plasma membrane. The low surface expression of CD4-β and δ loops was due to their pronounced retention in the Golgi apparatus and also to their rapid internalization from the plasma membrane. Both retention and recovery were mediated by the proximal 25-28 amino acids in each loop and were dependent on an ordered sequence of charged and hydrophobic residues. Indeed, βK353L and δK351L mutations increased surface trafficking of the CD4-subunit loops by >6-fold and also decreased their internalization from the plasma membrane. Similarly, combined βK353L and δK351L mutations increased the surface levels of assembled AChR expressed in HEK cells to 138% of wild-type levels. This was due to increased trafficking to the plasma membrane and not decreased AChR turnover. These findings identify novel Golgi retention signals in the β and δ subunit loops that regulate surface trafficking of assembled AChR and may help prevent surface expression of unassembled subunits. Together, these results define molecular determinants that govern a Golgi-based regulatory step in nicotinic AChR trafficking.
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20
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Functional down-regulation of axotomized rat facial motoneurons. Brain Res 2013; 1507:35-44. [DOI: 10.1016/j.brainres.2013.02.044] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2012] [Revised: 01/22/2013] [Accepted: 02/23/2013] [Indexed: 11/19/2022]
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21
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Channelopathies. Neurogenetics 2012. [DOI: 10.1017/cbo9781139087711.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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22
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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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23
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A retrospective review of 15 patients with familial myasthenia gravis over a period of 25 years. Neurol Sci 2011; 33:771-7. [DOI: 10.1007/s10072-011-0818-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2011] [Accepted: 10/06/2011] [Indexed: 10/15/2022]
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24
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Sadeh M, Shen XM, Engel AG. Beneficial effect of albuterol in congenital myasthenic syndrome with epsilon-subunit mutations. Muscle Nerve 2011; 44:289-91. [PMID: 21721016 DOI: 10.1002/mus.22153] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/25/2011] [Indexed: 11/06/2022]
Abstract
Mutations in the epsilon subunit of the acetylcholine receptor (AChR) are a common cause of congenital myasthenic syndrome (CMS). Patients are usually treated with acetylcholinesterase inhibitors and 3,4-diaminopyridine with modest clinical benefit. We report 2 patients with CMS due to mutations in the AChR epsilon subunit. The first patient carries two heterozygous frameshift mutations, ε127ins5 and ε1293insG. The second patient is homozygous for the εC142Y mutation that curtails AChR expression to 22% of wild-type in HEK cells. Treatment with pyridostigmine and 3,4-diaminopyridine had a limited beneficial effect in the first patient, and the second patient became wheelchair-bound during therapy. The additional use of albuterol produced dramatic improvement in strength and in activities of daily living in both patients. The efficacy and safety of albuterol in patients who harbor identified low-expressor or null mutations in the epsilon or other subunits of AChR merits a well-designed clinical trial.
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Affiliation(s)
- Menachem Sadeh
- Department of Neurology, Wolfson Medical Center, Holon and Tel Aviv University, Halochamin Street, Holon 58100, Israel.
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25
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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 PMCID: PMC3327811 DOI: 10.1016/j.nmd.2010.12.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [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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26
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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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27
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Miastenie e sindromi miasteniche. Neurologia 2011. [DOI: 10.1016/s1634-7072(11)70655-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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28
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Schara U, Christen HJ, Durmus H, Hietala M, Krabetz K, Rodolico C, Schreiber G, Topaloglu H, Talim B, Voss W, Pihko H, Abicht A, Müller JS, Lochmüller H. Long-term follow-up in patients with congenital myasthenic syndrome due to CHAT mutations. Eur J Paediatr Neurol 2010; 14:326-33. [PMID: 19900826 DOI: 10.1016/j.ejpn.2009.09.009] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2008] [Revised: 09/19/2009] [Accepted: 09/28/2009] [Indexed: 10/20/2022]
Abstract
BACKGROUND Congenital myasthenic syndromes (CMSs) are a group of clinically and genetically heterogeneous inherited disorders of the neuromuscular junction. Mutations in the acetylcholine transferase (CHAT) gene cause a pre-synaptic CMS, typically associated with episodic apnoea and worsening of myasthenic symptoms during crises caused by infections, fever or stress. Between crises symptoms may be mild and variable. Acetylcholinesterase - inhibitor therapy is reported to improve clinical symptoms and reduce crises. PATIENTS AND METHODS We present data on the long-term follow-up of 11 patients with a congenital myasthenic syndrome due to nine different CHAT mutations; ten of the patients have not been previously reported. RESULTS AND CONCLUSIONS Manifestation varied from the neonatal period to the age of two years, follow-up time from nine months to 12 years. This cohort of CHAT patients studied here enabled us to describe two distinct phenotypes: The neonatal-onset group suffers from apnoeic crises, respirator dependency and bulbar weakness. Apnoea should be carefully distinguished from seizures; a CMS should be taken into account early to start appropriate therapy. Infantile-onset patients show mild permanent weakness, but experience apnoeic crises and worsening which resolve with Acetylcholinesterase - inhibitor treatment. However, after several years of treatment proximal muscle strength may decrease and lead to wheelchair dependency despite the continuation of Acetylcholinesterase - inhibitor therapy.
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Affiliation(s)
- Ulrike Schara
- Dept. of Paediatric Neurology, University of Essen, Hufelandstr. 55, D-45122 Essen, Germany.
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29
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Yang ML, Finkel RS. Overview of paediatric neuromuscular disorders and related pulmonary issues: diagnostic and therapeutic considerations. Paediatr Respir Rev 2010; 11:9-17. [PMID: 20113986 DOI: 10.1016/j.prrv.2009.10.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Pulmonary compromise is common in neuromuscular disease. Respiratory failure may be a presenting feature of neuromuscular disease and remains a major cause of morbidity and mortality. This article will review the current understanding of the more commonly encountered neuromuscular disorders in childhood and emphasize related pulmonary issues.
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Affiliation(s)
- M L Yang
- Children's Hospital Denver, Aurora, CO 80045-7106, USA
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30
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Faber CG, Molenaar PC, Vles JSH, Bonifati DM, Verschuuren JJGM, van Doorn PA, Kuks JBM, Wokke JHJ, Beeson D, De Baets M. AChR deficiency due to epsilon-subunit mutations: two common mutations in the Netherlands. J Neurol 2009; 256:1719-23. [PMID: 19544078 PMCID: PMC2758211 DOI: 10.1007/s00415-009-5190-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2009] [Revised: 04/23/2009] [Accepted: 05/18/2009] [Indexed: 11/30/2022]
Abstract
Congenital myasthenic syndromes are a clinically and genetically heterogeneous group of hereditary disorders affecting neuromuscular transmission. We have identified mutations within the acetylcholine receptor (AChR) ε-subunit gene underlying congenital myasthenic syndromes in nine patients (seven kinships) of Dutch origin. Previously reported mutations ε1369delG and εR311Q were found to be common; ε1369delG was present on at least one allele in seven of the nine patients, and εR311Q in six. Phenotypes ranged from relatively mild ptosis and external ophthalmoplegia to generalized myasthenia. The common occurrence of εR311Q and ε1369delG suggests a possible founder for each of these mutations originating in North Western Europe, possibly in Holland. Knowledge of the ethnic or geographic origin within Europe of AChR deficiency patients can help in targeting genetic screening and it may be possible to provide a rapid genetic diagnosis for patients of Dutch origin by screening first for εR311Q and ε1369delG.
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Affiliation(s)
- Catharina G Faber
- Department of Neurology, Maastricht University Medical Centre, PO Box 5800, 6202 AZ, Maastricht, The Netherlands.
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31
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Lorenzoni PJ, Scola RH, Gervini BL, Kay CSK, Werneck LC. Electrophysiological study in synaptic congenital myasthenic syndrome: end-plate acetylcholinesterase deficiency. ARQUIVOS DE NEURO-PSIQUIATRIA 2009; 67:502-4. [DOI: 10.1590/s0004-282x2009000300024] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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32
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Nam S, Min K, Hwang H, Lee HO, Lee JH, Yoon J, Lee H, Park S, Lee J. Control of rapsyn stability by the CUL-3-containing E3 ligase complex. J Biol Chem 2009; 284:8195-206. [PMID: 19158078 PMCID: PMC3282941 DOI: 10.1074/jbc.m808230200] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2008] [Revised: 01/13/2009] [Indexed: 11/06/2022] Open
Abstract
Rapsyn is a postsynaptic protein required for clustering of nicotinic acetylcholine receptors (nAChRs) at the neuromuscular junction. Here we report the mechanism for posttranslational control of rapsyn protein stability. We confirmed that C18H9.7-encoded RPY-1 is a rapsyn homolog in Caenorhabditis elegans by showing that human rapsyn rescued rpy-1 mutant phenotypes in nematodes, as determined by levamisole assays and micropost array behavioral assays. We found that RPY-1 was degraded in the absence of functional UNC-29, a non-alpha subunit of the receptor, in an allele-specific manner, but not in the absence of other receptor subunits. The cytoplasmic loop of UNC-29 was found to be critical for RPY-1 stability. Through RNA interference screening, we found that UBC-1, UBC-12, NEDD-8, and RBX-1 were required for degradation of RPY-1. We identified cullin (CUL)-3 as a component of E3 ligase and KEL-8 as the substrate adaptor of RPY-1. Mammalian rapsyn was ubiquitinated by the CUL3/KLHL8-containing E3 ligase in vitro, and the knockdown of KLHL-8, a mammalian KEL-8 homolog, inhibited rapsyn ubiquitination in vivo, implying evolutionary conservation of the rapsyn stability control machinery. kel-8 suppression and rpy-1 overexpression in C. elegans produced a phenotype similar to that of a loss-of-function mutation of rpy-1, suggesting that control of rapsyn abundance is important for proper function of the receptor. Our results suggest a link between the control of rapsyn abundance and congenital myasthenic syndromes.
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Affiliation(s)
- Seunghee Nam
- Research Center for
Cellulomics, Institute of Molecular Biology and Genetics, School of Biological
Sciences, Seoul National University, 151-742 Seoul, Korea, the
Division of Nano Sciences (BK21),
Ewha Womans University, 120-750 Seoul, Korea,
Protein Network Research Center,
Department of Biochemistry, Yonsei University, 134 Shinchon, 120-749 Seoul,
Korea
| | - Kyoengwoo Min
- Research Center for
Cellulomics, Institute of Molecular Biology and Genetics, School of Biological
Sciences, Seoul National University, 151-742 Seoul, Korea, the
Division of Nano Sciences (BK21),
Ewha Womans University, 120-750 Seoul, Korea,
Protein Network Research Center,
Department of Biochemistry, Yonsei University, 134 Shinchon, 120-749 Seoul,
Korea
| | - Hyejin Hwang
- Research Center for
Cellulomics, Institute of Molecular Biology and Genetics, School of Biological
Sciences, Seoul National University, 151-742 Seoul, Korea, the
Division of Nano Sciences (BK21),
Ewha Womans University, 120-750 Seoul, Korea,
Protein Network Research Center,
Department of Biochemistry, Yonsei University, 134 Shinchon, 120-749 Seoul,
Korea
| | - Hae-ock Lee
- Research Center for
Cellulomics, Institute of Molecular Biology and Genetics, School of Biological
Sciences, Seoul National University, 151-742 Seoul, Korea, the
Division of Nano Sciences (BK21),
Ewha Womans University, 120-750 Seoul, Korea,
Protein Network Research Center,
Department of Biochemistry, Yonsei University, 134 Shinchon, 120-749 Seoul,
Korea
| | - Jung Hwa Lee
- Research Center for
Cellulomics, Institute of Molecular Biology and Genetics, School of Biological
Sciences, Seoul National University, 151-742 Seoul, Korea, the
Division of Nano Sciences (BK21),
Ewha Womans University, 120-750 Seoul, Korea,
Protein Network Research Center,
Department of Biochemistry, Yonsei University, 134 Shinchon, 120-749 Seoul,
Korea
| | - Jongbok Yoon
- Research Center for
Cellulomics, Institute of Molecular Biology and Genetics, School of Biological
Sciences, Seoul National University, 151-742 Seoul, Korea, the
Division of Nano Sciences (BK21),
Ewha Womans University, 120-750 Seoul, Korea,
Protein Network Research Center,
Department of Biochemistry, Yonsei University, 134 Shinchon, 120-749 Seoul,
Korea
| | - Hyunsook Lee
- Research Center for
Cellulomics, Institute of Molecular Biology and Genetics, School of Biological
Sciences, Seoul National University, 151-742 Seoul, Korea, the
Division of Nano Sciences (BK21),
Ewha Womans University, 120-750 Seoul, Korea,
Protein Network Research Center,
Department of Biochemistry, Yonsei University, 134 Shinchon, 120-749 Seoul,
Korea
| | - Sungsu Park
- Research Center for
Cellulomics, Institute of Molecular Biology and Genetics, School of Biological
Sciences, Seoul National University, 151-742 Seoul, Korea, the
Division of Nano Sciences (BK21),
Ewha Womans University, 120-750 Seoul, Korea,
Protein Network Research Center,
Department of Biochemistry, Yonsei University, 134 Shinchon, 120-749 Seoul,
Korea
| | - Junho Lee
- Research Center for
Cellulomics, Institute of Molecular Biology and Genetics, School of Biological
Sciences, Seoul National University, 151-742 Seoul, Korea, the
Division of Nano Sciences (BK21),
Ewha Womans University, 120-750 Seoul, Korea,
Protein Network Research Center,
Department of Biochemistry, Yonsei University, 134 Shinchon, 120-749 Seoul,
Korea
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Nogajski JH, Kiernan MC, Ouvrier RA, Andrews PI. Congenital myasthenic syndromes. J Clin Neurosci 2008; 16:1-11. [PMID: 19017561 DOI: 10.1016/j.jocn.2008.05.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2006] [Revised: 04/10/2008] [Accepted: 05/04/2008] [Indexed: 10/21/2022]
Abstract
Congenital myasthenic syndromes (CMS) are a heterogeneous group of uncommon, inherited disorders affecting the neuromuscular junction. The defects interfere with presynaptic, synaptic, or postsynaptic function and compromise neuromuscular transmission. Most patients with CMS have similar clinical features regardless of the underlying defect, but attention to clinical and electrodiagnostic parameters can narrow the diagnostic spectrum. Recent advances in our understanding of the cellular mechanisms underlying specific syndromes allow DNA testing for some forms of CMS. Diagnosis of CMS enables a rationale for management to be developed. Two cases of genetically determined CMS as well as an undiagnosed infant are presented to highlight the clinical and electrophysiological difficulties associated with the diagnosis and management of such syndromes.
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Affiliation(s)
- Joseph H Nogajski
- Institute of Neurological Sciences, Prince of Wales Hospital, Randwick, New South Wales, Australia
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Terblanche N, Maxwell C, Keunen J, Carvalho JCA. Obstetric and Anesthetic Management of Severe Congenital Myasthenia Syndrome. Anesth Analg 2008; 107:1313-5. [DOI: 10.1213/ane.0b013e3181823d11] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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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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37
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Anderson JA, Ng JJ, Bowe C, Mcdonald C, Richman DP, Wollmann RL, Maselli RA. Variable phenotypes associated with mutations inDOK7. Muscle Nerve 2008; 37:448-56. [DOI: 10.1002/mus.20944] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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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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Denning L, Anderson JA, Davis R, Gregg JP, Kuzdenyi J, Maselli RA. High throughput genetic analysis of congenital myasthenic syndromes using resequencing microarrays. PLoS One 2007; 2:e918. [PMID: 17878953 PMCID: PMC1975473 DOI: 10.1371/journal.pone.0000918] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2007] [Accepted: 08/22/2007] [Indexed: 11/19/2022] Open
Abstract
Background The use of resequencing microarrays for screening multiple, candidate disease loci is a promising alternative to conventional capillary sequencing. We describe the performance of a custom resequencing microarray for mutational analysis of Congenital Myasthenic Syndromes (CMSs), a group of disorders in which the normal process of neuromuscular transmission is impaired. Methodology/Principal Findings Our microarray was designed to assay the exons and flanking intronic regions of 8 genes linked to CMSs. A total of 31 microarrays were hybridized with genomic DNA from either individuals with known CMS mutations or from healthy controls. We estimated an overall microarray call rate of 93.61%, and we found the percentage agreement between the microarray and capillary sequencing techniques to be 99.95%. In addition, our microarray exhibited 100% specificity and 99.99% reproducibility. Finally, the microarray detected 22 out of the 23 known missense mutations, but it failed to detect all 7 known insertion and deletion (indels) mutations, indicating an overall sensitivity of 73.33% and a sensitivity with respect to missense mutations of 95.65%. Conclusions/Significance Overall, our microarray prototype exhibited strong performance and proved highly efficient for screening genes associated with CMSs. Until indels can be efficiently assayed with this technology, however, we recommend using resequencing microarrays for screening CMS mutations after common indels have been first assayed by capillary sequencing.
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Affiliation(s)
- Lisa Denning
- Department of Neurology, University of California at Davis, Davis, California, United States of America
| | - Jennifer A. Anderson
- Department of Neurology, University of California at Davis, Davis, California, United States of America
| | - Ryan Davis
- Department of Pathology, Medical Investigation of Neurodevelopmental Disorders Institute, University of California at Davis, Davis, California, United States of America
| | - Jeffrey P. Gregg
- Department of Pathology, Medical Investigation of Neurodevelopmental Disorders Institute, University of California at Davis, Davis, California, United States of America
| | - Jennifer Kuzdenyi
- Department of Neurology, University of California at Davis, Davis, California, United States of America
| | - Ricardo A. Maselli
- Department of Neurology, University of California at Davis, Davis, California, United States of America
- * To whom correspondence should be addressed. E-mail:
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Müller JS, Mihaylova V, Abicht A, Lochmüller H. Congenital myasthenic syndromes: spotlight on genetic defects of neuromuscular transmission. Expert Rev Mol Med 2007; 9:1-20. [PMID: 17686188 DOI: 10.1017/s1462399407000427] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The neuromuscular junction (NMJ) is a complex structure that efficiently communicates the electrical impulse from the motor neuron to the skeletal muscle to induce muscle contraction. Genetic and autoimmune disorders known to compromise neuromuscular transmission are providing further insights into the complexities of NMJ function. Congenital myasthenic syndromes (CMSs) are a genetically and phenotypically heterogeneous group of rare hereditary disorders affecting neuromuscular transmission. The understanding of the molecular basis of the different types of CMSs has evolved rapidly in recent years. Mutations were first identified in the subunits of the nicotinic acetylcholine receptor (AChR), but now mutations in ten different genes - encoding post-, pre- or synaptic proteins - are known to cause CMSs. Pathogenic mechanisms leading to an impaired neuromuscular transmission modify AChRs or endplate structure or lead to decreased acetylcholine synthesis and release. However, the genetic background of many CMS forms is still unresolved. A precise molecular classification of CMS type is of paramount importance for the diagnosis, counselling and therapy of a patient, as different drugs may be beneficial or deleterious depending on the molecular background of the particular CMS.
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Affiliation(s)
- Juliane S Müller
- Friedrich-Baur-Institute, Department of Neurology, Ludwig-Maximilians-University, Munich, Germany
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Abstract
In recent years, understanding of the pathogenesis and clinical presentation of distinct myasthenia subtypes has increased significantly. This article reviews the clinical manifestations of autoimmune myasthenia gravis (including myasthenia associated with anti-muscle-specific kinase antibodies), ocular myasthenia, and antibody negative myasthenia. The following treatments are examined: cholinesterase inhibitors, immunosuppressants, and thymectomy. Inherited congenital myasthenic syndromes (CMS) are now increasingly recognized, and most commonly present during childhood. This article outlines the presynaptic, synaptic basal lamina-associated, and postsynaptic classification of CMS and the clinical presentation and aetiology of individual syndromes. Relevant investigations and treatment options (including the role of pyridostigmine, 3,4-diaminopyridine, fluoxetine, and ephedrine) are discussed.
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Affiliation(s)
- J R Parr
- University of Oxford Department of Paediatrics, Children's Hospital, Oxford, UK.
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Richard P, Gaudon K, Fournier E, Jackson C, Bauché S, Haddad H, Koenig J, Echenne B, Hantaï D, Eymard B. A synonymous CHRNE mutation responsible for an aberrant splicing leading to congenital myasthenic syndrome. Neuromuscul Disord 2007; 17:409-14. [PMID: 17363247 DOI: 10.1016/j.nmd.2007.01.018] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2006] [Revised: 12/29/2006] [Accepted: 01/22/2007] [Indexed: 11/16/2022]
Abstract
Congenital myasthenic syndromes (CMSs) are rare hereditary disorders transmitted in a recessive or dominant pattern, and are caused by mutations in the genes encoding proteins of the neuromuscular junction. They are classified in three groups depending on the origin of the molecular defect. Postsynaptic defects are the most frequent and have been reported to be partly due to abnormalities of the acetylcholine receptor, and particularly to mutations in CHRNE, the gene encoding the acetylcholine receptor epsilon-subunit. In a Portuguese patient with a mild form of recessive CMS, CHRNE sequencing identified an unknown homozygous transition. This variation affects the third nucleotide of the glycine 285 condon, and leads to a synonymous variant. Analysis of transcripts demonstrated that this single change creates a new splice donor site located 4 nucleotides upstream of the normal site, leading to a deletion and generating a frameshift in exon 9 followed by a premature termination codon. This paper relates the identification of a synonymous mutation in CHRNE that creates a new splice donor site leading to an aberrant splicing of pre-mRNAs and so to their instability. This is the first synonymous mutation in CHRNE known to generate a cryptic splice site, and mRNA quantification strongly suggests that it is the disease-causing mutation.
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Affiliation(s)
- Pascale Richard
- AP-HP, Groupe Hospitalier Pitié-Salpêtrière, Unité Fonctionnelle de Cardiogénétique et Myogénétique, Service de Biochimie B, Paris, France.
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Ifergane G, Al-Sayed I, Birk O, Harel T, Wirguin I. Co-morbidity of Emery-Dreifuss muscular dystrophy and a congenital myasthenic syndrome possibly affecting the phenotype in a large Bedouin kindred. Eur J Neurol 2007; 14:305-8. [PMID: 17355552 DOI: 10.1111/j.1468-1331.2006.01657.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Emery-Dreifuss muscular dystrophy (EDMD) is an X-linked humero-peroneal muscular dystrophy associated with contractures and cardiomyopathy. In a 90 member family, we found 11 affected male individuals, three of whom displayed areflexia and neurogenic electromyographic changes. Muscle biopsy performed in one case demonstrated type grouping suggestive of a neurogenic disorder. These three individuals and another family member, who suffers from mild, static limb weakness but is clinically and genetically unaffected by EDMD showed an abnormal incremental response of over 100% to tetanic stimulation. In contrast, one affected family member showed myopathic features on needle electromyography and no definite pathology in repetitive stimulation studies. The diagnosis of EDMD was established by demonstrating a 1712_1713insTGGGC mutation in the emerin gene. This family apparently expresses co-morbidity of EDMD with an exceptionally mild form of pre-synaptic congenital myasthenic syndrome resembling the Lambert-Eaton myasthenic syndrome (LEMS). The superimposed pre-synaptic disorder may have contributed to the development of the neurogenic features demonstrated in these patients.
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MESH Headings
- Adolescent
- Adult
- Arabs/genetics
- Child
- Child, Preschool
- Comorbidity
- DNA Mutational Analysis
- Disease Progression
- Female
- Genetic Diseases, X-Linked/ethnology
- Genetic Diseases, X-Linked/genetics
- Genetic Diseases, X-Linked/physiopathology
- Genetic Linkage/genetics
- Genetic Predisposition to Disease/genetics
- Genetic Testing
- Genotype
- Humans
- Male
- Membrane Proteins/genetics
- Middle Aged
- Muscle, Skeletal/innervation
- Muscle, Skeletal/pathology
- Muscle, Skeletal/physiopathology
- Muscular Dystrophy, Emery-Dreifuss/ethnology
- Muscular Dystrophy, Emery-Dreifuss/genetics
- Muscular Dystrophy, Emery-Dreifuss/physiopathology
- Myasthenic Syndromes, Congenital/ethnology
- Myasthenic Syndromes, Congenital/genetics
- Myasthenic Syndromes, Congenital/physiopathology
- Nuclear Proteins/genetics
- Pedigree
- Phenotype
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Affiliation(s)
- G Ifergane
- Department of Neurology, Soroka Medical Center, Beer-Sheva, Israel
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Elenes S, Ni Y, Cymes GD, Grosman C. Desensitization contributes to the synaptic response of gain-of-function mutants of the muscle nicotinic receptor. ACTA ACUST UNITED AC 2006; 128:615-27. [PMID: 17074980 PMCID: PMC2151585 DOI: 10.1085/jgp.200609570] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Although the muscle nicotinic receptor (AChR) desensitizes almost completely in the steady presence of high concentrations of acetylcholine (ACh), it is well established that AChRs do not accumulate in desensitized states under normal physiological conditions of neurotransmitter release and clearance. Quantitative considerations in the framework of plausible kinetic schemes, however, lead us to predict that mutations that speed up channel opening, slow down channel closure, and/or slow down the dissociation of neurotransmitter (i.e., gain-of-function mutations) increase the extent to which AChRs desensitize upon ACh removal. In this paper, we confirm this prediction by applying high-frequency trains of brief (∼1 ms) ACh pulses to outside-out membrane patches expressing either lab-engineered or naturally occurring (disease-causing) gain-of-function mutants. Entry into desensitization was evident in our experiments as a frequency-dependent depression in the peak value of succesive macroscopic current responses, in a manner that is remarkably consistent with the theoretical expectation. We conclude that the comparatively small depression of the macroscopic currents observed upon repetitive stimulation of the wild-type AChR is due, not to desensitization being exceedingly slow but, rather, to the particular balance between gating, entry into desensitization, and ACh dissociation rate constants. Disruption of this fine balance by, for example, mutations can lead to enhanced desensitization even if the kinetics of entry into, and recovery from, desensitization themselves are not affected. It follows that accounting for the (usually overlooked) desensitization phenomenon is essential for the correct interpretation of mutagenesis-driven structure–function relationships and for the understanding of pathological synaptic transmission at the vertebrate neuromuscular junction.
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Affiliation(s)
- Sergio Elenes
- Department of Molecular and Integrative Physiology, Center for Biophysics and Computational Biology, and Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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Abstract
With increased life expectancy associated with improved respiratory care and research advances in pediatric neuromuscular diseases leading to clinical trials involving potential curative treatments, the goal in the care of the child with weakness is to optimize survival and quality of life. The care of the child with weakness includes management of motor dysfunction because of weakness, orthopedic complications of contractures and scoliosis, and comorbid complications specific to each neuromuscular disease. Optimal holistic integrative care of the multisystemic problems of such patients is best provided by the collaborative efforts of health care providers of an interdisciplinary team.
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Affiliation(s)
- Brenda L Wong
- Department of Pediatrics, Division of Pediatric Neurology, Cincinnati Children's Hospital Medical Center, University of Cincinnati, Cincinnati, OH 45229, USA.
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Lorenzoni PJ, Kay CSK, Arruda WO, Scola RH, Werneck LC. Estudo neurofisiológico na síndrome miastênica congênita do canal lento: relato de caso. ARQUIVOS DE NEURO-PSIQUIATRIA 2006; 64:318-21. [PMID: 16791378 DOI: 10.1590/s0004-282x2006000200028] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A síndrome do canal lento é uma das síndromes miastênicas congênitas atribuída a desordem dinâmica do canal iônico do receptor de acetilcolina da junção neuromuscular. Descrevemos o caso de um homem de 25 anos com progressiva ptose palpebral e limitação da movimentação ocular desde infância, que evoluiu há 6 anos com piora da oftalmoparesia externa e diminuição da força muscular em ombros e mãos. O estudo da condução nervosa motora após estímulo único demonstrou duplo potencial de ação muscular composto (PAMC) com desaparecimento do segundo após esforço de 30 segundos. Ao estímulo repetitivo dos nervos facial e acessório observou-se um decremento da amplitude do PAMC maior que 10% com desaparecimento do segundo potencial. O paciente fez uso de fluoxetina mostrando discreta melhora da força muscular, porém persiste com: ptose palpebral, limitação dos movimentos oculares e PAMC repetitivo ao estudo da condução nervosa motora. As características da doença são discutidas.
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Affiliation(s)
- Paulo José Lorenzoni
- Serviço de Doenças Neuromusculares, Hospital de Clínicas, Universidade Federal do Paraná, Curitiba, PR, Brazil
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Mourot A, Grutter T, Goeldner M, Kotzyba-Hibert F. Dynamic Structural Investigations on the Torpedo Nicotinic Acetylcholine Receptor by Time-Resolved Photoaffinity Labeling. Chembiochem 2006; 7:570-83. [PMID: 16538695 DOI: 10.1002/cbic.200500526] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
An increasing number of high-resolution structures of membrane-embedded ion channels (or soluble homologues) have emerged during the last couple of years. The most pressing need now is to understand the complex mechanism underlying ion-channel function. Time-resolved photoaffinity labeling is a suitable tool for investigating the molecular function of membrane proteins, especially when high-resolution structures of related proteins are available. However until now this methodology has only been used on the Torpedo nicotinic acetylcholine receptor (nAChR). nAChRs are allosteric cation-selective receptor channels that are activated by the neurotransmitter acetylcholine (ACh) and implicated in numerous physiological and pathological processes. Time-resolved photoaffinity labeling has already enabled local motions of nAChR subdomains (i.e. agonist binding sites, ion channel, subunit interface) to be understood at the molecular level, and has helped to explain how small molecules can exert their physiological effect, an important step toward the development of drug design. Recent analytical and technical improvements should allow the application of this powerful methodology to other membrane proteins in the near future.
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Affiliation(s)
- Alexandre Mourot
- Biophysical Chemistry Department, Max Planck Institut für Biophysik, Max-von-Laue Strasse 3, 60438 Frankfurt am Main, Germany.
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Fucile S, Sucapane A, Grassi F, Eusebi F, Engel AG. The human adult subtype ACh receptor channel has high Ca2+ permeability and predisposes to endplate Ca2+ overloading. J Physiol 2006; 573:35-43. [PMID: 16527851 PMCID: PMC1779694 DOI: 10.1113/jphysiol.2006.108092] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Slow-channel congenital myasthenic syndrome, caused by mutations in subunits of the endplate ACh receptor (AChR), results in prolonged synaptic currents and excitotoxic injury of the postsynaptic region by Ca2+ overloading. The Ca2+ overloading could be due entirely to the prolonged openings of the AChR channel or could be abetted by enhanced Ca2+ permeability of the mutant channels. We therefore measured the fractional Ca2+ current, defined as the percentage of the total ACh-evoked current carried by Ca2+ ions (Pf), for AChRs harbouring the alphaG153S or the alphaV249F slow-channel mutation, and for wild-type human AChRs in which Pf has not yet been determined. Experiments were performed in transiently transfected GH4C1 cells and human myotubes with simultaneous recording of ACh-evoked whole-cell currents and fura-2 fluorescence signals. We found that the Pf of the wild-type human endplate AChR was unexpectedly high (Pf approximately 7%), but neither the alphaV249F nor the alphaG153S mutation altered Pf. Fetal human AChRs containing either the wild-type or the mutated alpha subunit had a much lower Pf (2-3%). We conclude that the Ca2+ permeability of human endplate AChRs is higher than that reported for any other human nicotinic AChR, with the exception of alpha7-containing AChRs (Pf > 10%); and that neither the alphaG153S nor the alphaV249F mutations affect the Pf of fetal or adult endplate AChRs. However, the intrinsically high Ca2+ permeability of human AChRs probably predisposes to development of the endplate myopathy when opening events of the AChR channel are prolonged by altered AChR-channel kinetics.
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Affiliation(s)
- Sergio Fucile
- Pasteur Institute -Cenci Bolognetti Foundation & Department of Human Physiology and Pharmacology & Centre of Excellence for Biology and Molecular Medicine, University of Rome La Sapienza, Piazzale Aldo Moro 5; I-00185 Rome, Italy
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50
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Tidswell T, Pitt MC. A new analytical method to diagnose congenital myasthenia with stimulated single-fiber electromyography. Muscle Nerve 2006; 35:107-10. [PMID: 16941657 DOI: 10.1002/mus.20637] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Stimulated single-fiber electromyography (SSF-EMG) is useful to assess neuromuscular junction (NMJ) abnormalities in children. Conventionally mean consecutive difference (MCD) analysis measures the jitter for each muscle-fiber potential. We present a new algorithm that analyzes the entire SSF-EMG waveform. Cross-correlational coefficients (between 0-1.0) are calculated for consecutive pairs of 100 SSF-EMG waveforms obtained at each needle position in orbicularis oculi, and averaged. A lower normal limit (0.722, mean -3 SD) was established from 123 SSF-EMG samples in 10 adult control subjects, and applied to SSF-EMG data from 23 children referred for a suspected myasthenic syndrome. Results were compared with MCD analysis and related to the final clinical diagnosis. Our results showed that compared with conventional MCD measurement, the new algorithm had better specificity (87% vs. 53%) but similar sensitivity (88% for both). These findings indicate that the cross-correlational method is a useful predictor of NMJ dysfunction in children.
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Affiliation(s)
- Thomas Tidswell
- Department of Clinical Neurophysiology, Great Ormond Street Hospital for Children NHS Trust, Great Ormond Street, London WC1N 3JH, United Kingdom
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