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Murtazina A, Borovikov A, Marakhonov A, Sharkov A, Sharkova I, Mirzoyan A, Kulikova S, Ganieva R, Zabnenkova V, Ryzhkova O, Nikitin S, Dadali E, Kutsev S. Mild phenotype of CHAT-associated congenital myasthenic syndrome: case series. Front Pediatr 2024; 12:1280394. [PMID: 38304750 PMCID: PMC10830679 DOI: 10.3389/fped.2024.1280394] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/20/2023] [Accepted: 01/02/2024] [Indexed: 02/03/2024] Open
Abstract
Congenital myasthenic syndrome with episodic apnea is associated with pathogenic variants in the CHAT gene. While respiratory disorders and oculomotor findings are commonly reported in affected individuals, a subset of patients only present with muscle weakness and/or ptosis but not apneic crises. In this case series, we describe five individuals with exercise intolerance caused by single nucleotide variants in the CHAT gene. The age of onset ranged from 1 to 2.5 years, and all patients exhibited a fluctuating course of congenital myasthenic syndrome without disease progression over several years. Notably, these patients maintained a normal neurological status, except for the presence of abnormal fatigability in their leg muscles following prolonged physical activity. We conducted a modified protocol of repetitive nerve stimulation on the peroneal nerve, revealing an increased decrement in amplitude and area of compound muscle action potentials of the tibialis anterior muscle after 15-20 min of exercise. Treatment with 3,4-diaminopyridine showed clear improvement in two children, while one patient experienced severe adverse effects and is currently receiving a combination of Salbutamol Syrup and pyridostigmine with slight positive effects. Based on our findings and previous cases of early childhood onset with muscle fatigability as the sole manifestation, we propose the existence of a mild phenotype characterized by the absence of apneic episodes.
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Affiliation(s)
| | | | | | - Artem Sharkov
- Veltischev Research and Clinical Institute for Pediatrics of the Pirogov Russian National Research Medical University, Moscow, Russia
- Genomed Ltd., Moscow, Russia
| | - Inna Sharkova
- Research Centre for Medical Genetics, Moscow, Russia
| | - Alena Mirzoyan
- Republican Research and Clinical Center of Neurology and Neurosurgery, Minsk, Belarus
| | - Sviatlana Kulikova
- Republican Research and Clinical Center of Neurology and Neurosurgery, Minsk, Belarus
| | | | | | | | | | - Elena Dadali
- Research Centre for Medical Genetics, Moscow, Russia
| | - Sergey Kutsev
- Research Centre for Medical Genetics, Moscow, Russia
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Ohno K, Ohkawara B, Shen XM, Selcen D, Engel AG. Clinical and Pathologic Features of Congenital Myasthenic Syndromes Caused by 35 Genes-A Comprehensive Review. Int J Mol Sci 2023; 24:ijms24043730. [PMID: 36835142 PMCID: PMC9961056 DOI: 10.3390/ijms24043730] [Citation(s) in RCA: 26] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2023] [Revised: 02/09/2023] [Accepted: 02/09/2023] [Indexed: 02/16/2023] Open
Abstract
Congenital myasthenic syndromes (CMS) are a heterogeneous group of disorders characterized by impaired neuromuscular signal transmission due to germline pathogenic variants in genes expressed at the neuromuscular junction (NMJ). A total of 35 genes have been reported in CMS (AGRN, ALG14, ALG2, CHAT, CHD8, CHRNA1, CHRNB1, CHRND, CHRNE, CHRNG, COL13A1, COLQ, DOK7, DPAGT1, GFPT1, GMPPB, LAMA5, LAMB2, LRP4, MUSK, MYO9A, PLEC, PREPL, PURA, RAPSN, RPH3A, SCN4A, SLC18A3, SLC25A1, SLC5A7, SNAP25, SYT2, TOR1AIP1, UNC13A, VAMP1). The 35 genes can be classified into 14 groups according to the pathomechanical, clinical, and therapeutic features of CMS patients. Measurement of compound muscle action potentials elicited by repetitive nerve stimulation is required to diagnose CMS. Clinical and electrophysiological features are not sufficient to identify a defective molecule, and genetic studies are always required for accurate diagnosis. From a pharmacological point of view, cholinesterase inhibitors are effective in most groups of CMS, but are contraindicated in some groups of CMS. Similarly, ephedrine, salbutamol (albuterol), amifampridine are effective in most but not all groups of CMS. This review extensively covers pathomechanical and clinical features of CMS by citing 442 relevant articles.
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Affiliation(s)
- Kinji Ohno
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
- Correspondence: (K.O.); (A.G.E.)
| | - Bisei Ohkawara
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Xin-Ming Shen
- Department of Neurology and Neuromuscular Research Laboratory, Mayo Clinic, Rochester, MN 55905, USA
| | - Duygu Selcen
- Department of Neurology and Neuromuscular Research Laboratory, Mayo Clinic, Rochester, MN 55905, USA
| | - Andrew G. Engel
- Department of Neurology and Neuromuscular Research Laboratory, Mayo Clinic, Rochester, MN 55905, USA
- Correspondence: (K.O.); (A.G.E.)
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Pugliese A, Holland SH, Rodolico C, Lochmüller H, Spendiff S. Presynaptic Congenital Myasthenic Syndromes: Understanding Clinical Phenotypes through In vivo Models. J Neuromuscul Dis 2023; 10:731-759. [PMID: 37212067 PMCID: PMC10578258 DOI: 10.3233/jnd-221646] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/30/2023] [Indexed: 05/23/2023]
Abstract
Presynaptic congenital myasthenic syndromes (CMS) are a group of genetic disorders affecting the presynaptic side of the neuromuscular junctions (NMJ). They can result from a dysfunction in acetylcholine (ACh) synthesis or recycling, in its packaging into synaptic vesicles, or its subsequent release into the synaptic cleft. Other proteins involved in presynaptic endplate development and maintenance can also be impaired.Presynaptic CMS usually presents during the prenatal or neonatal period, with a severe phenotype including congenital arthrogryposis, developmental delay, and apnoeic crisis. However, milder phenotypes with proximal muscle weakness and good response to treatment have been described. Finally, many presynaptic genes are expressed in the brain, justifying the presence of additional central nervous system symptoms.Several animal models have been developed to study CMS, providing the opportunity to identify disease mechanisms and test treatment options. In this review, we describe presynaptic CMS phenotypes with a focus on in vivo models, to better understand CMS pathophysiology and define new causative genes.
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Affiliation(s)
- Alessia Pugliese
- Children’s Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada
- Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Stephen H. Holland
- Children’s Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada
- Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada
| | - Carmelo Rodolico
- Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Hanns Lochmüller
- Children’s Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada
- Department of Medicine, Division of Neurology, The Ottawa Hospital, Ottawa, ON, Canada
- Brain and Mind Research Institute, University of Ottawa, Ottawa, ON, Canada
- Department of Neuropediatrics and Muscle Disorders, Medical Center – University of Freiburg, Faculty of Medicine, Freiburg, Germany
- Centro Nacional de Análisis Genómico (CNAG-CRG), Center for Genomic Regulation, Barcelona Institute of Science and Technology (BIST), Barcelona, Catalonia, Spain
| | - Sally Spendiff
- Children’s Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada
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Tan KA, Chew HB, Yacob Y, Khoo TB. A Common CHAT Gene Mutation of Congenital Myasthenic Syndrome Found in Kadazandusun Children. J Pediatr Genet 2022. [DOI: 10.1055/s-0042-1750747] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
Abstract
AbstractCongenital myasthenic syndrome (CMS) is an uncommon inherited neuromuscular junction disease. The clinical presentation of this disorder is diverse. Typically patients with this disorder present with early-onset swallowing difficulty and apnea in infancy, fluctuating ocular palsies and fatigable proximal muscle weakness during childhood, and late-onset form involving progressive weakness in adulthood. Difficulty in performing neurophysiology studies in children and the absence of a pathognomonic investigation marker increase the challenges in diagnosis of this disorder. The emergence of next-generation sequencing technology has circumvented these challenges somewhat, and has contributed to the discovery of novel mutations. We present here diagnostic odyssey of three CMS patients from two unrelated Kadazandusun kinships and their follow-up treatment. A rare homozygous mutation c.916G > C (p.Val306Leu) in CHAT gene was found in two siblings born of a consanguineous marriage. Third patient had compound heterozygous mutations c.406G > A (p.Val136Met) and c.916G > C (p.Val306Leu) in CHAT gene. We postulate that p.Val306Leu may be a founder mutation in the Kadazandusuns, an indigenous ethnic minority of Borneo Island.
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Affiliation(s)
- Khian Aun Tan
- Pediatric Neurology Unit, Hospital Tunku Azizah, Kuala Lumpur, Malaysia
| | - Hui Bein Chew
- Genetic Department, Hospital Kuala Lumpur, Kuala Lumpur, Malaysia
| | - Yusnita Yacob
- Molecular Diagnostics Unit, Institute for Medical Research, National Institutes of Health, Selangor, Malaysia
| | - Teik Beng Khoo
- Pediatric Neurology Unit, Hospital Tunku Azizah, Kuala Lumpur, Malaysia
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5
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Ramdas S, Beeson D. Congenital myasthenic syndromes: where do we go from here? Neuromuscul Disord 2021; 31:943-954. [PMID: 34736634 DOI: 10.1016/j.nmd.2021.07.400] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 07/22/2021] [Accepted: 07/27/2021] [Indexed: 11/27/2022]
Abstract
Congenital myasthenia syndromes are rare but often treatable conditions affecting neuromuscular transmission. They result from loss or impaired function of one of a number of proteins secondary to a genetic defect. An estimate of the prevalence in the UK gave 9.2 cases per million, however, this is likely an underestimate since the adoption of next generation sequencing for diagnosis away from specialist centres is enhancing the 'pick up' rate. Next generation sequencing has helped identify a series of novel genes that harbour mutations causative for congenital myasthenic syndrome that include not only genes that encode proteins specifically expressed at the neuromuscular junction but also those that are ubiquitously expressed. The list of genes harbouring disease-causing mutations for congenital myasthenic syndrome continues to expand and is now over 30, but with many of the newly identified genes it is increasingly being recognised that abnormal neuromuscular transmission is only one component of a multifaceted phenotype in which muscle, the central nervous system, and other organs may also be affected. Treatment can be tailored to the underlying molecular mechanism for impaired neuromuscular transmission but treating the more complex multifaceted disorders and will require development of new therapies.
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Affiliation(s)
- Sithara Ramdas
- MDUK Neuromuscular centre, Children's Hospital, John Radcliffe Hospital, Oxford, OX3 9DU, UK
| | - David Beeson
- Neurosciences Group, Weatherall Institute of Molecular Medicine, The John Radcliffe, Oxford OX3 9DS, UK.
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Duerr JS, McManus JR, Crowell JA, Rand JB. Analysis of C. elegans acetylcholine synthesis mutants reveals a temperature-sensitive requirement for cholinergic neuromuscular function. Genetics 2021; 218:6283614. [PMID: 34028515 DOI: 10.1093/genetics/iyab078] [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: 02/01/2021] [Accepted: 05/04/2021] [Indexed: 11/13/2022] Open
Abstract
In Caenorhabditis elegans, the cha-1 gene encodes choline acetyltransferase (ChAT), the enzyme that synthesizes the neurotransmitter acetylcholine. We have analyzed a large number of cha-1 hypomorphic mutants, most of which are missense alleles. Some homozygous cha-1 mutants have approximately normal ChAT immunoreactivity; many other alleles lead to consistent reductions in synaptic immunostaining, although the residual protein appears to be stable. Regardless of protein levels, neuromuscular function of almost all mutants is temperature sensitive, i.e., neuromuscular function is worse at 25° than at 14°. We show that the temperature effects are not related to acetylcholine release, but specifically to alterations in acetylcholine synthesis. This is not a temperature-dependent developmental phenotype, because animals raised at 20° to young adulthood and then shifted for 2 hours to either 14° or 25° had swimming and pharyngeal pumping rates similar to animals grown and assayed at either 14° or 25°, respectively. We also show that the temperature-sensitive phenotypes are not limited to missense alleles; rather, they are a property of most or all severe cha-1 hypomorphs. We suggest that our data are consistent with a model of ChAT protein physically, but not covalently, associated with synaptic vesicles; and there is a temperature-dependent equilibrium between vesicle-associated and cytoplasmic (i.e., soluble) ChAT. Presumably, in severe cha-1 hypomorphs, increasing the temperature would promote dissociation of some of the mutant ChAT protein from synaptic vesicles, thus removing the site of acetylcholine synthesis (ChAT) from the site of vesicular acetylcholine transport. This, in turn, would decrease the rate and extent of vesicle-filling, thus increasing the severity of the behavioral deficits.
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Affiliation(s)
- Janet S Duerr
- Genetic Models of Disease Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA.,Department of Biological Sciences, Ohio University, Athens, Ohio 45701, USA
| | - John R McManus
- Genetic Models of Disease Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA
| | - John A Crowell
- Genetic Models of Disease Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA
| | - James B Rand
- Genetic Models of Disease Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA.,Oklahoma Center for Neuroscience, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
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Janežič M, Dileep KV, Zhang KYJ. A multidimensional computational exploration of congenital myasthenic syndrome causing mutations in human choline acetyltransferase. J Cell Biochem 2021; 122:787-800. [PMID: 33650116 DOI: 10.1002/jcb.29913] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Revised: 02/08/2021] [Accepted: 02/09/2021] [Indexed: 11/09/2022]
Abstract
Missense mutations of human choline acetyltransferase (CHAT) are mainly associated with congenital myasthenic syndrome (CMS). To date, several pathogenic mutations have been reported, but due to the rarity and genetic complexity of CMS and difficult genotype-phenotype correlations, the CHAT mutations, and their consequences are underexplored. In this study, we systematically sift through the available genetic data in search of previously unreported pathogenic mutations and use a dynamic in silico model to provide structural explanations for the pathogenicity of the reported deleterious and undetermined variants. Through rigorous multiparameter analyses, we conclude that mutations can affect CHAT through a variety of different mechanisms: by disrupting the secondary structure, by perturbing the P-loop through long-range allosteric interactions, by disrupting the domain connecting loop, and by affecting the phosphorylation process. This study provides the first dynamic look at how mutations affect the structure and catalytic activity in CHAT and highlights the need for further genomic research to better understand the pathology of CHAT.
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Affiliation(s)
- Matej Janežič
- Laboratory for Structural Bioinformatics, Center for Biosystems Dynamics Research, RIKEN, Yokohama, Kanagawa, Japan.,Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Chiba, Japan
| | - Kalarickal V Dileep
- Laboratory for Structural Bioinformatics, Center for Biosystems Dynamics Research, RIKEN, Yokohama, Kanagawa, Japan
| | - Kam Y J Zhang
- Laboratory for Structural Bioinformatics, Center for Biosystems Dynamics Research, RIKEN, Yokohama, Kanagawa, Japan.,Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Chiba, Japan
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Zhang Y, Cheng X, Luo C, Lei M, Mao F, Shi Z, Cao W, Zhang J, Zhang Q. Congenital Myasthenic Syndrome Caused by a Novel Hemizygous CHAT Mutation. Front Pediatr 2020; 8:185. [PMID: 32411636 PMCID: PMC7198756 DOI: 10.3389/fped.2020.00185] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Accepted: 03/30/2020] [Indexed: 02/02/2023] Open
Abstract
Congenital myasthenic syndrome (CMS) is a neuromuscular transmission disorder caused by mutations in genes encoding neuromuscular junction proteins. CMS due to choline acetyltransferase (CHAT) gene mutation is characterized by episodic apnoea. To date, 52 cases of CMS caused by CHAT gene mutations have been reported. Here, we report a neonate with the third hemizygous mutation [a 4.9 Mb deletion [10q11.22-10q11.23 (chr10: 46123781-51028772)] containing the whole CHAT gene and c.1976A>T (p.Gln659Leu in the CHAT gene)]. The c.1976A>T (p.Gln659Leu) variant had not been reported in the ExAC or gnomAD databases and was predicted to be pathogenic. The alignment of amino acid sequences revealed that glutamine at codon 659 is highly conserved in different species and causes structural changes in the substrate-binding site. Our female patient with neonate-onset CMS presented with apnoea, dyspnoea, feeding difficulties, weak crying, and seizure-like episodes, and her respiration was ventilator dependent. The prostigmine test was positive. This case may help to further elucidate clinical features and treatment methods in neonate-onset CMS caused by CHAT gene mutations.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Qian Zhang
- Neonatal Intensive Care Unit, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
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Nicole S, Azuma Y, Bauché S, Eymard B, Lochmüller H, Slater C. Congenital Myasthenic Syndromes or Inherited Disorders of Neuromuscular Transmission: Recent Discoveries and Open Questions. J Neuromuscul Dis 2019; 4:269-284. [PMID: 29125502 PMCID: PMC5701762 DOI: 10.3233/jnd-170257] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Congenital myasthenic syndromes (CMS) form a heterogeneous group of rare diseases characterized by fatigable muscle weakness. They are genetically-inherited and caused by defective synaptic transmission at the cholinergic neuromuscular junction (NMJ). The number of genes known to cause CMS when mutated is currently 30, and the relationship between fatigable muscle weakness and defective functions is quite well-understood for many of them. However, some of the most recent discoveries in individuals with CMS challenge our knowledge of the NMJ, where the basis of the pathology has mostly been investigated in animal models. Frontier forms between CMS and congenital myopathy, which have been genetically and clinically identified, underline the poorly understood interplay between the synaptic and extrasynaptic molecules in the neuromuscular system. In addition, precise electrophysiological and histopathological investigations of individuals with CMS suggest an important role of NMJ plasticity in the response to CMS pathogenesis. While efficient drug-based treatments are already available to improve neuromuscular transmission for most forms of CMS, others, as well as neurological and muscular comorbidities, remain resistant. Taken together, the available pathological data point to physiological issues which remain to be understood in order to achieve precision medicine with efficient therapeutics for all individuals suffering from CMS.
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Affiliation(s)
- Sophie Nicole
- Inserm U 1127, CNRS UMR 7225, Sorbonne Universités, UPMC Université Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle épinière, ICM, 75013 Paris, France
| | - Yoshiteru Azuma
- John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine, Newcastle University, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK
| | - Stéphanie Bauché
- Inserm U 1127, CNRS UMR 7225, Sorbonne Universités, UPMC Université Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle épinière, ICM, 75013 Paris, France
| | - Bruno Eymard
- Inserm U 1127, CNRS UMR 7225, Sorbonne Universités, UPMC Université Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle épinière, ICM, 75013 Paris, France.,AP-HP, Hôpital Pitié-Salpétrière, 75013 Paris, France
| | - Hanns Lochmüller
- John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine, Newcastle University, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK
| | - Clarke Slater
- Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK
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Nicolau S, Milone M. The Electrophysiology of Presynaptic Congenital Myasthenic Syndromes With and Without Facilitation: From Electrodiagnostic Findings to Molecular Mechanisms. Front Neurol 2019; 10:257. [PMID: 30941097 PMCID: PMC6433874 DOI: 10.3389/fneur.2019.00257] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Accepted: 02/26/2019] [Indexed: 11/13/2022] Open
Abstract
Congenital myasthenic syndromes (CMS) are a group of inherited disorders of neuromuscular transmission most commonly presenting with early onset fatigable weakness, ptosis, and ophthalmoparesis. CMS are classified according to the localization of the causative molecular defect. CMS with presynaptic dysfunction can be caused by mutations in several different genes, including those involved in acetylcholine synthesis, its packaging into synaptic vesicles, vesicle docking, and release from the presynaptic nerve terminal and neuromuscular junction development and maintenance. Electrodiagnostic testing is key in distinguishing CMS from other neuromuscular disorders with similar clinical features as well as for revealing features pointing to a specific molecular diagnosis. A decremental response on low-frequency repetitive nerve stimulation (RNS) is present in most presynaptic CMS. In CMS with deficits in acetylcholine resynthesis however, a decrement may only appear after conditioning with exercise or high-frequency RNS and characteristically displays a slow recovery. Facilitation occurs in CMS caused by mutations in VAMP1, UNC13A, SYT2, AGRN, LAMA5. By contrast, facilitation is absent in the other presynaptic CMS described to date. An understanding of the underlying molecular mechanisms therefore assists the interpretation of electrodiagnostic findings in patients with suspected CMS.
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Affiliation(s)
- Stefan Nicolau
- Department of Neurology, Mayo Clinic, Rochester, MN, United States
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Mutation of a serine near the catalytic site of the choline acetyltransferase a gene almost completely abolishes motility of the zebrafish embryo. PLoS One 2018; 13:e0207747. [PMID: 30458023 PMCID: PMC6245786 DOI: 10.1371/journal.pone.0207747] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Accepted: 11/06/2018] [Indexed: 12/29/2022] Open
Abstract
In zebrafish, the gene choline acetyltransferase a (chata) encodes one of the two ChAT orthologs responsible for the synthesis of acetylcholine. Acetylcholine (ACh) is essential for neuromuscular transmission and its impaired synthesis by ChAT can lead to neuromuscular junction disorders such as congenital myasthenic syndromes in humans. We have identified a novel mutation in the chata gene of zebrafish, chatatk64, in a collection of uncharacterised ENU-induced mutants. This mutant carries a missense mutation in the codon of a highly conserved serine changing it to an arginine (S102R). This serine is conserved among ChATs from zebrafish, rat, mice and chicken to humans. It resides within the catalytic domain and in the vicinity of the active site of the enzyme. However, it has not been reported so far to be required for enzymatic activity. Modelling of the S102R variant change in the ChAT protein crystal structure suggests that the change affects protein structure and has a direct impact on the catalytic domain of the protein which abolishes embryo motility almost completely.
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12
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CHAT gene polymorphism rs3810950 is associated with the risk of Alzheimer's disease in the Czech population. J Biomed Sci 2018; 25:41. [PMID: 29759072 PMCID: PMC5950140 DOI: 10.1186/s12929-018-0444-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Accepted: 05/07/2018] [Indexed: 12/24/2022] Open
Abstract
Background Cholinergic hypothesis of Alzheimer’s disease (AD) is based on the findings that a reduced and/or perturbed cholinergic activity in the central nervous system correlates with cognitive decline in patients with Alzheimer’s disease. The hypothesis resulted in the development of centrally-acting agents potentiating cholinergic neurotransmission; these drugs, however, only slowed down the cognitive decline and could not prevent it. Consequently, the perturbation of the central cholinergic signalling has been accepted as a part of the Alzheimer’s aetiology but not necessarily the primary cause of the disease. In the present study we have focused on the rs3810950 polymorphism of ChAT (choline acetyltransferase) gene that has not been studied in Czech population before. Methods We carried out an association study to test for a relationship between the rs3810950 polymorphism and Alzheimer’s disease in a group of 1186 persons; 759 patients with Alzheimer’s disease and 427 control subjects. Furthermore, we performed molecular modelling of the terminal domain (1st-126th amino acid residue) of one of the ChAT isoforms (M) to visualise in silico whether the rs3810950 polymorphism (A120T) can change any features of the tertiary structure of the protein which would have a potential to alter its function. Results The AA genotype of CHAT was associated with a 1.25 times higher risk of AD (p < 0.002) thus demonstrating that the rs3810950 polymorphism can have a modest but statistically significant effect on the risk of AD in the Czech population. Furthermore, the molecular modelling indicated that the polymorphism is likely to be associated with significant variations in the tertiary structure of the protein molecule which may impact its enzyme activity. Conclusions Our findings are consistent with the results of the meta-analytical studies of the relationship between rs3810950 polymorphism and AD and provide further material evidence for a direct (primary) involvement of cholinergic mechanisms in the etiopathogenesis of AD, particularly as a factor in cognitive decline and perturbed conscious awareness commonly observed in patients with AD.
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Abstract
PURPOSE OF REVIEW Congenital myasthenic syndromes (CMS) are a group of heterogeneous inherited disorders caused by mutations in genes encoding proteins essential for the integrity of neuromuscular transmission. This review updates the reader on recent findings that have expanded the phenotypic spectrum and suggested improved treatment strategies. RECENT FINDINGS The use of next-generation sequencing is continuing to unearth new genes in which mutations can give rise to defective neuromuscular transmission. The defective transmission may be part of an overall more complex phenotype in which there may be muscle, central nervous system or other involvement. Notably, mutations in series of genes encoding presynaptic proteins are being identified. Further work on mutations found in the AGRN-MUSK acetylcholine receptor clustering pathway has helped characterize the role of LRP4 and broadened the phenotypic spectrum for AGRN mutations. Mutations in another extracellular matrix protein, collagen 13A1 and in GMPPB have also been found to cause a CMS. Finally, there are an increasing number of reports for the beneficial effects of treatment with β2-adrenergic receptor agonists. SUMMARY Recent studies of the CMS illustrate the increasing complexity of the genetics, pathophysiological mechanisms and the need to tailor therapy for the genetic disorders of the neuromuscular junction.
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McMacken G, Whittaker RG, Evangelista T, Abicht A, Dusl M, Lochmüller H. Congenital myasthenic syndrome with episodic apnoea: clinical, neurophysiological and genetic features in the long-term follow-up of 19 patients. J Neurol 2018; 265:194-203. [PMID: 29189923 PMCID: PMC5760613 DOI: 10.1007/s00415-017-8689-3] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Revised: 11/19/2017] [Accepted: 11/20/2017] [Indexed: 12/14/2022]
Abstract
BACKGROUND Congenital myasthenic syndrome with episodic apnoea (CMS-EA) is a rare but potentially treatable cause of apparent life-threatening events in infancy. The underlying mechanisms for sudden and recurrent episodes of respiratory arrest in these patients are unclear. Whilst CMS-EA is most commonly caused by mutations in CHAT, the list of associated genotypes is expanding. METHODS We reviewed clinical information from 19 patients with CMS-EA, including patients with mutations in CHAT, SLC5A7 and RAPSN, and patients lacking a genetic diagnosis. RESULTS Lack of genetic diagnosis was more common in CMS-EA than in CMS without EA (56% n = 18, compared to 7% n = 97). Most patients manifested intermittent apnoea in the first 4 months of life (74%, n = 14). A degree of clinical improvement with medication was observed in most patients (74%, n = 14), but the majority of cases also showed a tendency towards complete remission of apnoeic events with age (mean age of resolution 2 years 5 months). Signs of impaired neuromuscular transmission were detected on neurophysiology studies in 79% (n = 15) of cases, but in six cases, this was only apparent following specific neurophysiological testing protocols (prolonged high-frequency stimulation). CONCLUSIONS A relatively large proportion of CMS-EA remains genetically undiagnosed, which suggests the existence of novel causative CMS genes which remain uncharacterised. In light of the potential for recurrent life-threatening apnoeas in early life and the positive response to therapy, early diagnostic consideration of CMS-EA is critical, but without specific neurophysiology tests, it may go overlooked.
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Affiliation(s)
- Grace McMacken
- John Walton Muscular Dystrophy Research Centre, MRC Centre for Neuromuscular Diseases, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK.
| | - Roger G Whittaker
- Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - Teresinha Evangelista
- John Walton Muscular Dystrophy Research Centre, MRC Centre for Neuromuscular Diseases, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
| | - Angela Abicht
- Friedrich-Baur-Institute, Ludwig Maximilians University, Munich, Germany
| | - Marina Dusl
- Friedrich-Baur-Institute, Ludwig Maximilians University, Munich, Germany
| | - Hanns Lochmüller
- John Walton Muscular Dystrophy Research Centre, MRC Centre for Neuromuscular Diseases, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
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15
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Morey TM, Winick-Ng W, Seah C, Rylett RJ. Chaperone-Mediated Regulation of Choline Acetyltransferase Protein Stability and Activity by HSC/HSP70, HSP90, and p97/VCP. Front Mol Neurosci 2017; 10:415. [PMID: 29311808 PMCID: PMC5733026 DOI: 10.3389/fnmol.2017.00415] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Accepted: 11/30/2017] [Indexed: 11/13/2022] Open
Abstract
Choline acetyltransferase (ChAT) synthesizes the neurotransmitter acetylcholine in cholinergic neurons, and mutations of this enzyme are linked to the neuromuscular disorder congenital myasthenic syndrome (CMS). One CMS-related mutation, V18M, reduces ChAT enzyme activity and cellular protein levels, and is located within a highly-conserved N-terminal proline-rich motif at residues 14PKLPVPP20. We showed previously that disruption of this proline-rich motif by either proline-to-alanine mutation (P17A/P19A) or mutation of residue Val18 (V18M) enhances ubiquitination and degradation of these mutant ChAT proteins expressed in cholinergic SN56 cells by an unknown mechanism. In this study, using proximity-dependent biotin identification (BioID), co-immunoprecipitation and in situ proximity-ligation assay (PLA), we identified the heat shock proteins (HSPs) HSC/HSP70 and HSP90 as novel ChAT protein-interactors. These molecular chaperones are well-known for promoting the folding and stabilization of cellular proteins. Thus, we found that inhibition of HSPs by treatment of cells with either the HSC/HSP70 inhibitors 2-phenylethynesulfonamide (PES) or VER-155008, or the HSP90 inhibitor 17-AAG reduced cellular ChAT activity and solubility, and enhanced the ubiquitination and proteasome-dependent loss of ChAT protein. Importantly, the effects of HSP inhibition were greater for mutant ChAT proteins (P17A/P19A-ChAT and CMS-related V18M- and A513T-ChAT) compared to wild-type ChAT. HSPs can promote ubiquitination and degradation of terminally misfolded proteins through cooperative interaction with the E3 ubiquitin ligase CHIP/Stub1, and while we show that ChAT interacts with CHIP in situ, siRNA-mediated knock-down of CHIP had no effect on either wild-type or mutant ChAT protein levels. However, inhibition of the endoplasmic reticulum (ER)- and HSP-associated co-chaperone p97/VCP prevented degradation of ubiquitinated ChAT. Together, these results identify novel mechanisms for the functional regulation of wild-type and CMS-related mutant ChAT by pro-stabilizing HSPs and the pro-degradative co-chaperone p97/VCP that may have broader implications for ChAT function during cellular stress and disease.
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Affiliation(s)
- Trevor M Morey
- Molecular Medicine Research Laboratories, Robarts Research Institute, University of Western Ontario, London, ON, Canada.,Department of Physiology and Pharmacology, Schulich School of Medicine & Dentistry, University of Western Ontario, London, ON, Canada
| | - Warren Winick-Ng
- Molecular Medicine Research Laboratories, Robarts Research Institute, University of Western Ontario, London, ON, Canada.,Department of Physiology and Pharmacology, Schulich School of Medicine & Dentistry, University of Western Ontario, London, ON, Canada.,Epigenetic Regulation and Chromatin Architecture Group, Berlin Institute for Medical Systems Biology, Max-Delbrück Centre for Molecular Medicine, Berlin, Germany
| | - Claudia Seah
- Molecular Medicine Research Laboratories, Robarts Research Institute, University of Western Ontario, London, ON, Canada
| | - R Jane Rylett
- Molecular Medicine Research Laboratories, Robarts Research Institute, University of Western Ontario, London, ON, Canada.,Department of Physiology and Pharmacology, Schulich School of Medicine & Dentistry, University of Western Ontario, London, ON, Canada
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16
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Schwartz M, Sternberg D, Whalen S, Afenjar A, Isapof A, Chabrol B, Portnoï MF, Heide S, Keren B, Chantot-Bastaraud S, Siffroi JP. How chromosomal deletions can unmask recessive mutations? Deletions in 10q11.2 associated with CHAT or SLC18A3 mutations lead to congenital myasthenic syndrome. Am J Med Genet A 2017; 176:151-155. [PMID: 29130637 DOI: 10.1002/ajmg.a.38515] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2017] [Revised: 09/24/2017] [Accepted: 09/26/2017] [Indexed: 11/06/2022]
Abstract
A congenital myasthenia was suspected in two unrelated children with very similar phenotypes including several episodes of severe dyspnea. Both children had a 10q11.2 deletion revealed by Single Nucleotide Polymorphisms array or by Next Generation Sequencing analysis. The deletion was inherited from the healthy mother in the first case. These deletions unmasked a recessive mutation at the same locus in both cases, but in two different genes: CHAT and SLC18A3.
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Affiliation(s)
- Mathias Schwartz
- AP-HP, Département de Génétique Médicale, Hôpital Armand Trousseau, UPMC, Paris, France
| | - Damien Sternberg
- AP-HP, Hôpital Pitié-Salpêtrière, Biochimie et Génétique, Inserm U 1127, CNRS UMR 7225, Sorbonne Universités, UPMC Univ Paris 06 UMR S 1127, ICM, Paris, France
| | - Sandra Whalen
- AP-HP, Hôpital Armand Trousseau, UF de Génétique Clinique, UPMC, Paris, France
| | - Alexandra Afenjar
- AP-HP, Hôpital Armand Trousseau, UF de Génétique Clinique, UPMC, Paris, France
| | - Arnaud Isapof
- AP-HP, Hôpital Armand Trousseau, Unité de Neuropédiatrie et Pathologie du Développement, UPMC, Paris, France
| | - Brigitte Chabrol
- CHU de Marseille, Hôpital de la Timone, Service de Neurologie Pédiatrique, Inserm U1127, CNRS UMR 7225, UPMC, Centre de Recherche de l'Institut du Cerveau et de la Moëlle épinière, Paris, France
| | - Marie-France Portnoï
- AP-HP, Département de Génétique Médicale, Hôpital Armand Trousseau, UPMC, Paris, France
| | - Solveig Heide
- AP-HP, Département de Génétique Médicale, Hôpital Armand Trousseau, UPMC, Paris, France
| | - Boris Keren
- AP-HP, Département de Génétique, Hôpital de la Pitié Salpêtrière, Paris, France
| | | | - Jean-Pierre Siffroi
- AP-HP, Département de Génétique Médicale, Hôpital Armand Trousseau, UPMC, Paris, France
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17
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Wang H, Salter CG, Refai O, Hardy H, Barwick KES, Akpulat U, Kvarnung M, Chioza BA, Harlalka G, Taylan F, Sejersen T, Wright J, Zimmerman HH, Karakaya M, Stüve B, Weis J, Schara U, Russell MA, Abdul-Rahman OA, Chilton J, Blakely RD, Baple EL, Cirak S, Crosby AH. Choline transporter mutations in severe congenital myasthenic syndrome disrupt transporter localization. Brain 2017; 140:2838-2850. [PMID: 29088354 DOI: 10.1093/brain/awx249] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Accepted: 08/05/2017] [Indexed: 11/12/2022] Open
Abstract
The presynaptic, high-affinity choline transporter is a critical determinant of signalling by the neurotransmitter acetylcholine at both central and peripheral cholinergic synapses, including the neuromuscular junction. Here we describe an autosomal recessive presynaptic congenital myasthenic syndrome presenting with a broad clinical phenotype due to homozygous choline transporter missense mutations. The clinical phenotype ranges from the classical presentation of a congenital myasthenic syndrome in one patient (p.Pro210Leu), to severe neurodevelopmental delay with brain atrophy (p.Ser94Arg) and extend the clinical outcomes to a more severe spectrum with infantile lethality (p.Val112Glu). Cells transfected with mutant transporter construct revealed a virtually complete loss of transport activity that was paralleled by a reduction in transporter cell surface expression. Consistent with these findings, studies to determine the impact of gene mutations on the trafficking of the Caenorhabditis elegans choline transporter orthologue revealed deficits in transporter export to axons and nerve terminals. These findings contrast with our previous findings in autosomal dominant distal hereditary motor neuropathy of a dominant-negative frameshift mutation at the C-terminus of choline transporter that was associated with significantly reduced, but not completely abrogated choline transporter function. Together our findings define divergent neuropathological outcomes arising from different classes of choline transporter mutation with distinct disease processes and modes of inheritance. These findings underscore the essential role played by the choline transporter in sustaining acetylcholine neurotransmission at both central and neuromuscular synapses, with important implications for treatment and drug selection.
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Affiliation(s)
- Haicui Wang
- University Hospital Cologne, Department of Pediatrics, Kerpener Str. 62, 50937 Cologne, Germany.,Center for Molecular Medicine Cologne (CMMC), University of Cologne, Robert-Koch-Str. 21, 50931 Cologne, Germany
| | - Claire G Salter
- RILD Wellcome Wolfson Centre, Royal Devon and Exeter NHS Foundation Trust, Barrack Road, Exeter, EX2 5DW, UK.,Human Genetics and Genomic Medicine, Faculty of Medicine, University of Southampton, Southampton, SO16 6YD, UK
| | - Osama Refai
- Department of Biomedical Science, Charles E. Schmidt College of Medicine and Brain Institute, Florida Atlantic University, Jupiter, FL, USA
| | - Holly Hardy
- RILD Wellcome Wolfson Centre, Royal Devon and Exeter NHS Foundation Trust, Barrack Road, Exeter, EX2 5DW, UK
| | - Katy E S Barwick
- RILD Wellcome Wolfson Centre, Royal Devon and Exeter NHS Foundation Trust, Barrack Road, Exeter, EX2 5DW, UK
| | - Ugur Akpulat
- University Hospital Cologne, Department of Pediatrics, Kerpener Str. 62, 50937 Cologne, Germany.,Center for Molecular Medicine Cologne (CMMC), University of Cologne, Robert-Koch-Str. 21, 50931 Cologne, Germany.,Kastamonu University, 37150 Kastamonu, Turkey
| | - Malin Kvarnung
- Department of Molecular Medicine and Surgery, Center for Molecular Medicine, Karolinska Institutet, 17176 Stockholm, Sweden.,Department of Clinical Genetics, Karolinska University Hospital, 17176 Stockholm, Sweden
| | - Barry A Chioza
- RILD Wellcome Wolfson Centre, Royal Devon and Exeter NHS Foundation Trust, Barrack Road, Exeter, EX2 5DW, UK
| | - Gaurav Harlalka
- RILD Wellcome Wolfson Centre, Royal Devon and Exeter NHS Foundation Trust, Barrack Road, Exeter, EX2 5DW, UK
| | - Fulya Taylan
- Department of Molecular Medicine and Surgery, Center for Molecular Medicine, Karolinska Institutet, 17176 Stockholm, Sweden.,Science for Life Laboratory, Karolinska Institutet Science Park, 17121 Stockholm, Sweden
| | - Thomas Sejersen
- Science for Life Laboratory, Karolinska Institutet Science Park, 17121 Stockholm, Sweden.,Department of Women's and Children's Health, Division of Pediatric Neurology, Karolinska Institutet, 17176 Stockholm, Sweden
| | - Jane Wright
- Department of Pharmacology, Vanderbilt University, Nashville, TN, USA
| | - Holly H Zimmerman
- Division of Medical Genetics, University of Mississippi Medical Center, Jackson, Mississippi 39216, USA
| | - Mert Karakaya
- Center for Molecular Medicine Cologne (CMMC), University of Cologne, Robert-Koch-Str. 21, 50931 Cologne, Germany
| | - Burkhardt Stüve
- Children's Hospital Social Pediatric Center, 50735 Cologne, Germany
| | - Joachim Weis
- Institute of Neuropathology and Jülich Aachen Research Alliance (JARA) Brain Translational Medicine, RWTH Aachen University, 52074 Aachen, Germany
| | - Ulrike Schara
- University Children's Hospital Essen, Essen, Germany
| | - Mark A Russell
- RILD Wellcome Wolfson Centre, Royal Devon and Exeter NHS Foundation Trust, Barrack Road, Exeter, EX2 5DW, UK
| | - Omar A Abdul-Rahman
- Department of Pediatrics, University of Mississippi Medical Center, Jackson, Mississippi 39216, USA
| | - John Chilton
- RILD Wellcome Wolfson Centre, Royal Devon and Exeter NHS Foundation Trust, Barrack Road, Exeter, EX2 5DW, UK
| | - Randy D Blakely
- Department of Biomedical Science, Charles E. Schmidt College of Medicine and Brain Institute, Florida Atlantic University, Jupiter, FL, USA
| | - Emma L Baple
- RILD Wellcome Wolfson Centre, Royal Devon and Exeter NHS Foundation Trust, Barrack Road, Exeter, EX2 5DW, UK
| | - Sebahattin Cirak
- University Hospital Cologne, Department of Pediatrics, Kerpener Str. 62, 50937 Cologne, Germany.,Center for Molecular Medicine Cologne (CMMC), University of Cologne, Robert-Koch-Str. 21, 50931 Cologne, Germany
| | - Andrew H Crosby
- RILD Wellcome Wolfson Centre, Royal Devon and Exeter NHS Foundation Trust, Barrack Road, Exeter, EX2 5DW, UK
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