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Periviita V, Männikkö R, Jokela M, Sud R, Hanna MG, Udd B, Palmio J. Novel SCN4A Variants Associated With Myalgic Myotonic Disorder or Paramyotonia. Eur J Neurol 2025; 32:e70157. [PMID: 40344301 PMCID: PMC12062868 DOI: 10.1111/ene.70157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2025] [Revised: 03/12/2025] [Accepted: 04/03/2025] [Indexed: 05/11/2025]
Abstract
BACKGROUND This study aimed to determine the role of five new rare SCN4A variants suspected to cause paramyotonia or myotonic disorder. METHODS Ten patients from seven families underwent clinical, neurophysiological, imaging, and muscle biopsy examinations. Genetic studies were performed with targeted sequencing of all known myopathy genes. Functional changes resulting from these variants were studied with HEK293T cells, by using a whole-cell patch clamp. RESULTS Five SCN4A variants were identified: c.662 T > C p.(F221S), c.2143G > A p.(A715T), c.4352G > A p.(R1451H), c.3610 A > G p.(N1204D), and c.4255 T > C, p.(F1419L). Patients had exercise- and/or cold-induced myalgia, muscle stiffness or cramping, and varying degrees of muscle weakness. On examination, some but not all patients had percussion myotonia or findings compatible with paramyotonia. One patient with the A715T variant also had eyelid myotonia. The patient with the F221S variant had ptosis, weakness in hip flexion, and mild muscle hypertrophy in the calves. EMG showed myotonic discharges in all the patients examined except for the patient with N1204D. Electrophysiological exercise tests demonstrated results compatible with the Fournier pattern in six patients. All but the N1204D variant showed gain-of-function features upon functional expression. CONCLUSIONS The clinical and genetic findings suggested that all five variants were pathogenic, whereas functional data did not confirm association with myotonia for N1204D. Our results expand the mutational spectrum of the SCN4A gene. The reported variants should be considered in patients with paramyotonia, or in patients with exercise-induced myalgia or muscle cramping and who demonstrate myotonia in EMG.
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Affiliation(s)
- Vesa Periviita
- Department of NeurologyTampere University HospitalTampereFinland
| | - Roope Männikkö
- UCL Queen Square Institute of NeurologyDepartment of Neuromuscular DiseaseLondonUK
| | - Manu Jokela
- NeurocenterTurku University HospitalTurkuFinland
- Clinical NeurosciencesUniversity of TurkuTurkuFinland
| | - Richa Sud
- UCL Queen Square Institute of NeurologyDepartment of Neuromuscular DiseaseLondonUK
| | - Michael G. Hanna
- UCL Queen Square Institute of NeurologyDepartment of Neuromuscular DiseaseLondonUK
| | - Bjarne Udd
- Neuromuscular Research CenterTampere University and University HospitalTampereFinland
- Folkhälsan Research CenterHelsinkiFinland
| | - Johanna Palmio
- Neuromuscular Research CenterTampere University and University HospitalTampereFinland
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Deng H, Zhang Q, Yi J, Yuan L. Unraveling ptosis: A comprehensive review of clinical manifestations, genetics, and treatment. Prog Retin Eye Res 2025; 105:101327. [PMID: 39725023 DOI: 10.1016/j.preteyeres.2024.101327] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2024] [Revised: 12/21/2024] [Accepted: 12/23/2024] [Indexed: 12/28/2024]
Abstract
Ptosis is defined as an abnormally low-lying upper eyelid margin on the primary gaze, generally resulting from a congenital or acquired abnormality of the nerves or muscles that control the eyelid. Ptosis can occur alone or concurrently as an ocular or systemic syndrome, and the prevalence of ptosis varies among different countries and populations. Isolated ptosis typically causes aesthetic problems in patients and can lead to functional ophthalmic problems in severe cases. In individuals with syndromic ptosis, ptosis can be a warning of serious medical problems. There are different approaches to classification, depending on the onset time or the etiology of ptosis, and the clinical characteristics of congenital and acquired ptosis also differ. Pedigree and genetic analysis have demonstrated that hereditary ptosis is clinically heterogeneous, with incomplete concordance and variable expressivity. A number of genetic loci and genes responsible for hereditary isolated and syndromic ptosis have been reported. Optimal surgical timing and proper method are truly critical for avoiding the risk of potentially severe outcomes from ptosis and minimizing surgical complications, which are challenging as the pathogenesis is still indistinct and the anatomy is complex. This review provides a comprehensive review of ptosis, by summarizing the clinical manifestations, classification, diagnosis, genetics, treatment, and prognosis, as well as the bound anatomy of upper eyelid.
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Affiliation(s)
- Hao Deng
- Health Management Center, The Third Xiangya Hospital, Central South University, Changsha, 410013, China; Research Center of Medical Experimental Technology, The Third Xiangya Hospital, Central South University, Changsha, 410013, China; Center for Experimental Medicine, The Third Xiangya Hospital, Central South University, Changsha, 410013, China; Disease Genome Research Center, Central South University, Changsha, 410013, China; Department of Laboratory Medicine, The Third Xiangya Hospital, Central South University, Changsha, 410013, China.
| | - Qianling Zhang
- Health Management Center, The Third Xiangya Hospital, Central South University, Changsha, 410013, China; Department of Laboratory Medicine, The Third Xiangya Hospital, Central South University, Changsha, 410013, China.
| | - Junhui Yi
- Department of Ophthalmology, The Third Xiangya Hospital, Central South University, Changsha, 410013, China.
| | - Lamei Yuan
- Health Management Center, The Third Xiangya Hospital, Central South University, Changsha, 410013, China; Research Center of Medical Experimental Technology, The Third Xiangya Hospital, Central South University, Changsha, 410013, China; Center for Experimental Medicine, The Third Xiangya Hospital, Central South University, Changsha, 410013, China; Disease Genome Research Center, Central South University, Changsha, 410013, China.
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3
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Liu K, Wang L, Wen S, Qiu X, Cao P, Liang P, Wu S. Role of mutation G255A in modulating pyrethroid sensitivity in insect sodium channels. Int J Biol Macromol 2025; 295:139455. [PMID: 39778843 DOI: 10.1016/j.ijbiomac.2025.139455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2024] [Revised: 12/19/2024] [Accepted: 01/01/2025] [Indexed: 01/11/2025]
Abstract
A voltage-gated sodium channel (VGSC) plays a crucial role in insect electrical signals, and it is a target for various naturally occurring and synthesized neurotoxins, including pyrethroids and dichlorodiphenyltrichloroethane. The type of agent is typically widely used to prevent and control sanitary and agricultural pests. The perennial use of insecticides has caused mutations in VGSCs that have given rise to resistance in most insects. These mutations are located among the two pyrethroid receptors, i.e., PyR1 and PyR2, as predicted by previous studies. The two binding regions are relatively symmetrical, and here we focus on the linkers between S4 and S5 of Domains I and II. The S4-S5 linker can promote a rapid increase in sodium current and the onset of action potential. By predicting mutations in 19 other amino acids at all the amino acids on S4-S5 linkers, their harmfulness is analyzed, and whether they affect protein stability and drug binding is determined. Through molecular docking and based on docking scores, four mutations were predicted to affect the binding of sodium channels to pyrethroids. Mutations G255V, G255A, A906V, and A906T were introduced into the VGSC of Blattella germanica (BgNav1-1), and their effects on channel gating and pyrethroid sensitivity in Xenopus oocytes were studied. The treatment of VGSCs with two types of pyrethroids (1 nM), Types I (permethrin, bifenthrin) and II (deltamethrin, λ-cyhalothrin), produced tail currents. Among the four, mutant G255A exhibited a certain degree of increased sensitivity to the two types of pyrethroids. This finding was in contrast with the three other mutations, which demonstrated a certain degree of sensitization to one or two pyrethroids. We predicted and validated the critical mutation G255A on the insect VGSC Domain I S4-S5 linker using by electrophysiological technology. In generally, under the pressure of many insecticides, gene modifications, such as transcriptional changes and point mutations in the coding region make insects resistant to insecticides. This phenomenon leads to a higher detoxification rate of insecticides and makes the target site insensitive. However, we found that G255A mutation could promote the combination of pyrethroid and VGSCs by changing the binding force with insecticides. This finding has potential application value in reversing insect resistance. The discovery of mutation G255A exhibits considerable significance for the current use of gene editing and gene drive technology to control pests and delay their resistance development.
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Affiliation(s)
- Kaiyang Liu
- School of Breeding and Multiplication (Sanya Institute of Breeding and Multiplication), Hainan University, Sanya 572024, China; School of Tropical Agriculture and Forestry (School of Agricultural and Rural Affairs, School of Rural Revitalization), Hainan University, Danzhou 571700, China
| | - Likui Wang
- Department of Entomology, College of Plant Protection, and Sanya Institute of China Agricultural University, Beijing 100193, China
| | - Shuxuan Wen
- School of Breeding and Multiplication (Sanya Institute of Breeding and Multiplication), Hainan University, Sanya 572024, China; School of Tropical Agriculture and Forestry (School of Agricultural and Rural Affairs, School of Rural Revitalization), Hainan University, Danzhou 571700, China
| | - Xinyao Qiu
- School of Breeding and Multiplication (Sanya Institute of Breeding and Multiplication), Hainan University, Sanya 572024, China; School of Tropical Agriculture and Forestry (School of Agricultural and Rural Affairs, School of Rural Revitalization), Hainan University, Danzhou 571700, China
| | - Peng Cao
- Key Laboratory of Drug Targets and Drug Leads for Degenerative Diseases, Affiliated Hospital of Integrated Traditional Chinese and Western Medicine, Nanjing University of Chinese Medicine, Nanjing 210023, China
| | - Pei Liang
- Department of Entomology, College of Plant Protection, and Sanya Institute of China Agricultural University, Beijing 100193, China
| | - Shaoying Wu
- School of Breeding and Multiplication (Sanya Institute of Breeding and Multiplication), Hainan University, Sanya 572024, China; School of Tropical Agriculture and Forestry (School of Agricultural and Rural Affairs, School of Rural Revitalization), Hainan University, Danzhou 571700, China.
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4
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Kubota T, Nagata M, Takagi K, Ishihara Y, Kojima K, Uchikura Y, Yamamoto R, Yonei A, Ozaki E, Kira N, Takahashi S, Homma K, Miyashita Y, Eguchi-Ishimae M, Sakai N, Asano Y, Sakata Y, Ozono K, Eguchi M, Takahashi MP. Hydrops fetalis due to loss of function of hNav1.4 channel via compound heterozygous variants. J Hum Genet 2025; 70:3-8. [PMID: 39164360 PMCID: PMC11700836 DOI: 10.1038/s10038-024-01284-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2024] [Revised: 07/08/2024] [Accepted: 07/30/2024] [Indexed: 08/22/2024]
Abstract
Hydrops fetalis, characterized by abnormal fluid accumulation in fetuses, presents a significant risk of stillbirth and neonatal mortality. Although the etiology of nonimmune hydrops fetalis (NIHF) is multifaceted, recent studies have highlighted genetic factors as crucial determinants. This study focused on a family with three consecutive stillbirths, each with pronounced hydrops fetalis. Using whole-exome sequencing (WES), we identified compound heterozygous variants of the SCN4A gene encoding the voltage-gated sodium channel of the skeletal muscle (hNav1.4), c.2429T>A p.L810Q and c.4556T>C p.F1519S, in all three deceased infants. A functional analysis conducted using the whole-cell patch-clamp technique revealed loss-of-function defects in both variant channels, with F1519S exhibiting a complete loss of ionic current and L810Q showing a reduced channel opening. These findings support the pathogenicity of SCN4A variants in NIHF and underscore the significance of functional studies in elucidating genotype-phenotype correlations. Furthermore, our study emphasizes the diagnostic value of WES in cases of NIHF in where standard genetic testing fails to identify causative variants.
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Affiliation(s)
- Tomoya Kubota
- Clinical Neurophysiology, Department of Clinical Laboratory and Biomedical Sciences, Osaka University Graduate School of Medicine, Suita, Osaka, 5650871, Japan
| | - Miho Nagata
- Department of Cardiovascular Medicine (IRUD Analysis Center), Osaka University Graduate School of Medicine, Suita, Osaka, 5650871, Japan
| | - Kazuko Takagi
- Department of Obstetrics and Gynecology, Ehime University Graduate School of Medicine, Touon, Ehime, 7910295, Japan
| | - Yasuki Ishihara
- Department of Cardiovascular Medicine (IRUD Analysis Center), Osaka University Graduate School of Medicine, Suita, Osaka, 5650871, Japan
| | - Kurumi Kojima
- Clinical Neurophysiology, Department of Clinical Laboratory and Biomedical Sciences, Osaka University Graduate School of Medicine, Suita, Osaka, 5650871, Japan
| | - Yuka Uchikura
- Department of Obstetrics and Gynecology, Ehime University Graduate School of Medicine, Touon, Ehime, 7910295, Japan
| | - Reina Yamamoto
- Clinical Neurophysiology, Department of Clinical Laboratory and Biomedical Sciences, Osaka University Graduate School of Medicine, Suita, Osaka, 5650871, Japan
| | - Ayumi Yonei
- Division of Genetic Counselling, Osaka University Hospital, Suita, Osaka, 5650871, Japan
| | - Erina Ozaki
- Division of Medical Genetics, Ehime University Hospital, Touon, Ehime, 7910295, Japan
| | - Natsuki Kira
- Clinical Neurophysiology, Department of Clinical Laboratory and Biomedical Sciences, Osaka University Graduate School of Medicine, Suita, Osaka, 5650871, Japan
| | - Satoe Takahashi
- Department of Otolaryngology-Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
| | - Kazuaki Homma
- Department of Otolaryngology-Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
- The Hugh Knowles Center for Clinical and Basic Science in Hearing and Its Disorders, Northwestern University, Evanston, IL, 60208, USA
| | - Yohei Miyashita
- Department of Cardiovascular Medicine (IRUD Analysis Center), Osaka University Graduate School of Medicine, Suita, Osaka, 5650871, Japan
| | - Minenori Eguchi-Ishimae
- Division of Medical Genetics, Ehime University Hospital, Touon, Ehime, 7910295, Japan
- Department of Pediatrics, Ehime University Graduate School of Medicine, Touon, Ehime, 7910295, Japan
| | - Norio Sakai
- Division of Genetic Counselling, Osaka University Hospital, Suita, Osaka, 5650871, Japan
- Department of Pediatrics, Osaka University Graduate School of Medicine, Suita, Osaka, 5650871, Japan
| | - Yohihiro Asano
- Department of Cardiovascular Medicine (IRUD Analysis Center), Osaka University Graduate School of Medicine, Suita, Osaka, 5650871, Japan.
| | - Yasushi Sakata
- Department of Cardiovascular Medicine (IRUD Analysis Center), Osaka University Graduate School of Medicine, Suita, Osaka, 5650871, Japan
| | - Keiichi Ozono
- Department of Pediatrics, Osaka University Graduate School of Medicine, Suita, Osaka, 5650871, Japan
| | - Mariko Eguchi
- Division of Medical Genetics, Ehime University Hospital, Touon, Ehime, 7910295, Japan.
- Department of Pediatrics, Ehime University Graduate School of Medicine, Touon, Ehime, 7910295, Japan.
| | - Masanori P Takahashi
- Clinical Neurophysiology, Department of Clinical Laboratory and Biomedical Sciences, Osaka University Graduate School of Medicine, Suita, Osaka, 5650871, Japan.
- Division of Genetic Counselling, Osaka University Hospital, Suita, Osaka, 5650871, Japan.
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5
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Kaplan MM, Zeidler M, Knapp A, Hölzl M, Kress M, Fritsch H, Krogsdam A, Flucher BE. Spatial transcriptomics in embryonic mouse diaphragm muscle reveals regional gradients and subdomains of developmental gene expression. iScience 2024; 27:110018. [PMID: 38883818 PMCID: PMC11177202 DOI: 10.1016/j.isci.2024.110018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Revised: 03/22/2024] [Accepted: 05/14/2024] [Indexed: 06/18/2024] Open
Abstract
The murine embryonic diaphragm is a primary model for studying myogenesis and neuro-muscular synaptogenesis, both representing processes regulated by spatially organized genetic programs of myonuclei located in distinct myodomains. However, a spatial gene expression pattern of embryonic mouse diaphragm has not been reported. Here, we provide spatially resolved gene expression data for horizontally sectioned embryonic mouse diaphragms at embryonic days E14.5 and E18.5. These data reveal gene signatures for specific muscle regions with distinct maturity and fiber type composition, as well as for a central neuromuscular junction (NMJ) and a peripheral myotendinous junction (MTJ) compartment. Comparing spatial expression patterns of wild-type mice with those of transgenic mice lacking either the skeletal muscle calcium channel CaV1.1 or β-catenin, reveals curtailed muscle development and dysregulated expression of genes potentially involved in NMJ formation. Altogether, these datasets provide a powerful resource for further studies of muscle development and NMJ formation in the mouse.
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Affiliation(s)
| | - Maximilian Zeidler
- Institute of Physiology, Medical University Innsbruck, 6020 Innsbruck, Austria
| | - Annabella Knapp
- Institute of Clinical and Functional Anatomy, Medical University Innsbruck, 6020 Innsbruck, Austria
| | - Martina Hölzl
- Deep Sequencing Core and Institute for Bioinformatics Medical University Innsbruck, 6020 Innsbruck, Austria
| | - Michaela Kress
- Institute of Physiology, Medical University Innsbruck, 6020 Innsbruck, Austria
| | - Helga Fritsch
- Institute of Clinical and Functional Anatomy, Medical University Innsbruck, 6020 Innsbruck, Austria
| | - Anne Krogsdam
- Deep Sequencing Core and Institute for Bioinformatics Medical University Innsbruck, 6020 Innsbruck, Austria
| | - Bernhard E Flucher
- Institute of Physiology, Medical University Innsbruck, 6020 Innsbruck, Austria
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Periviita V, Jokela M, Palmio J, Udd B. A retrospective study of accuracy and usefulness of electrophysiological exercise tests. J Neurol 2024; 271:1802-1812. [PMID: 38055022 PMCID: PMC10972914 DOI: 10.1007/s00415-023-12110-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Revised: 10/26/2023] [Accepted: 11/09/2023] [Indexed: 12/07/2023]
Abstract
OBJECTIVES This study aimed to determine the usefulness of electrophysiological exercise tests. The significance of slightly abnormal exercise tests was also examined. METHODS We identified all the patients who had undergone exercise testing between February 2007 to June 2022 in Tampere University Hospital, Finland. Their medical records after diagnostic workup and exercise test reports were reviewed. A binary logistic regression was performed to evaluate the association between positive test result in short exercise test, long exercise test, or short exercise test with cooling and genetically confirmed skeletal muscle channelopathy or myotonic disorder. RESULTS We identified 256 patients. 27 patients were diagnosed with nondystrophic myotonia, periodic paralysis, myotonic dystrophy type 1, myotonic dystrophy type 2, or other specified myopathy. 14 patients were suspected to have a skeletal muscle channelopathy, but pathogenic variants could not be identified. The remaining 215 patients were diagnosed with other conditions than skeletal muscle channelopathy or myotonic disorder. The combined sensitivity of exercise tests was 59.3% and specificity 99.1%. Abnormal exercise test result was associated with increased risk of skeletal muscle channelopathy or myotonic disorder (OR 164.3, 95% CI 28.3-954.6, p < 0.001). CONCLUSIONS Electrophysiological exercise test is not optimal to exclude skeletal muscle channelopathy. It may be useful if a skeletal muscle channelopathy is suspected and genetic testing is negative or indeterminate and further evidence is required. Slightly abnormal exercise test results are possible in various conditions and result from different aetiologies. There is a demand for neurophysiological studies with higher sensitivity to detect skeletal muscle channelopathies.
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Affiliation(s)
- Vesa Periviita
- Department of Clinical Neurophysiology, Tampere University Hospital, Tampere, Finland.
| | - Manu Jokela
- Neuromuscular Research Center, Tampere University and University Hospital, Tampere, Finland
- Neurocenter, Turku University Hospital, Turku, Finland
- Neurology, Clinical Medicine, University of Turku, Turku, Finland
| | - Johanna Palmio
- Neuromuscular Research Center, Tampere University and University Hospital, Tampere, Finland
| | - Bjarne Udd
- Neuromuscular Research Center, Tampere University and University Hospital, Tampere, Finland
- Folkhälsan Research Center, Helsinki, Finland
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Hadjipanteli A, Theodosiou A, Papaevripidou I, Evangelidou P, Alexandrou A, Salameh N, Kallikas I, Kakoullis K, Frakala S, Oxinou C, Marnerides A, Kousoulidou L, Anastasiadou VC, Sismani C. Sodium Channel Gene Variants in Fetuses with Abnormal Sonographic Findings: Expanding the Prenatal Phenotypic Spectrum of Sodium Channelopathies. Genes (Basel) 2024; 15:119. [PMID: 38255008 PMCID: PMC10815715 DOI: 10.3390/genes15010119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Revised: 01/08/2024] [Accepted: 01/17/2024] [Indexed: 01/24/2024] Open
Abstract
Voltage-gated sodium channels (VGSCs) are responsible for the initiation and propagation of action potentials in the brain and muscle. Pathogenic variants in genes encoding VGSCs have been associated with severe disorders including epileptic encephalopathies and congenital myopathies. In this study, we identified pathogenic variants in genes encoding the α subunit of VGSCs in the fetuses of two unrelated families with the use of trio-based whole exome sequencing, as part of a larger cohort study. Sanger sequencing was performed for variant confirmation as well as parental phasing. The fetus of the first family carried a known de novo heterozygous missense variant in the SCN2A gene (NM_001040143.2:c.751G>A p.(Val251Ile)) and presented intrauterine growth retardation, hand clenching and ventriculomegaly. Neonatally, the proband also exhibited refractory epilepsy, spasms and MRI abnormalities. The fetus of the second family was a compound heterozygote for two parentally inherited novel missense variants in the SCN4A gene (NM_000334.4:c.4340T>C, p.(Phe1447Ser), NM_000334.4:c.3798G>C, p.(Glu1266Asp)) and presented a severe prenatal phenotype including talipes, fetal hypokinesia, hypoplastic lungs, polyhydramnios, ear abnormalities and others. Both probands died soon after birth. In a subsequent pregnancy of the latter family, the fetus was also a compound heterozygote for the same parentally inherited variants. This pregnancy was terminated due to multiple ultrasound abnormalities similar to the first pregnancy. Our results suggest a potentially crucial role of the VGSC gene family in fetal development and early lethality.
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Affiliation(s)
- Andrea Hadjipanteli
- The Cyprus Institute of Neurology and Genetics, Cytogenetics and Genomics, 2371 Nicosia, Cyprus; (A.H.)
| | - Athina Theodosiou
- The Cyprus Institute of Neurology and Genetics, Cytogenetics and Genomics, 2371 Nicosia, Cyprus; (A.H.)
| | - Ioannis Papaevripidou
- The Cyprus Institute of Neurology and Genetics, Cytogenetics and Genomics, 2371 Nicosia, Cyprus; (A.H.)
| | - Paola Evangelidou
- The Cyprus Institute of Neurology and Genetics, Cytogenetics and Genomics, 2371 Nicosia, Cyprus; (A.H.)
| | - Angelos Alexandrou
- The Cyprus Institute of Neurology and Genetics, Cytogenetics and Genomics, 2371 Nicosia, Cyprus; (A.H.)
| | - Nicole Salameh
- The Cyprus Institute of Neurology and Genetics, Cytogenetics and Genomics, 2371 Nicosia, Cyprus; (A.H.)
| | | | | | | | - Christina Oxinou
- Christina Oxinou Histopathology/Cytology Laboratory, 1065 Nicosia, Cyprus
| | | | - Ludmila Kousoulidou
- The Cyprus Institute of Neurology and Genetics, Cytogenetics and Genomics, 2371 Nicosia, Cyprus; (A.H.)
| | | | - Carolina Sismani
- The Cyprus Institute of Neurology and Genetics, Cytogenetics and Genomics, 2371 Nicosia, Cyprus; (A.H.)
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8
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Chan TYC, Hung LY, Lam TYL, Sheng B, Leung FYK, Lee HHC. SCN4A-related congenital myopathy in a Han Chinese patient: A case report and literature review. Heliyon 2024; 10:e23663. [PMID: 38187266 PMCID: PMC10770507 DOI: 10.1016/j.heliyon.2023.e23663] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Revised: 11/23/2023] [Accepted: 12/09/2023] [Indexed: 01/09/2024] Open
Abstract
SCN4A mutations have been shown to be associated with myotonia, paramyotonia congenita, and periodic paralyses. More recently, loss-of-function variants in the SCN4A gene were also noted to be associated with rarer, autosomal recessive forms of congenital myasthenic syndrome and congenital myopathy. Diagnosis is challenging as the initial clinical presentation and histological features on muscle biopsies are non-specific. We report a Han Chinese patient presented with congenital myopathy with two missense SCN4A variants. The patient had an antenatal history of reduced fetal movements, polyhydramnios and a very preterm birth. At birth, she was noted to have low Apgar score, respiratory distress syndrome and hypotonia. Delayed motor development was noted in early childhood. Dysmorphic features such as an elongated face, dolichocephaly and high arched palate were present. At 16 years of age, the patient developed progressive muscle weakness and was wheelchair-bound by age 20. Muscle biopsy revealed non-specific changes only. Targeted hereditary myopathy panel testing by next generation sequencing revealed two previously unreported missense variants c.1841A > T p.(Asn614Ile) and c.4420G > A p.(Ala1474Thr) in the SCN4A gene. The clinical features of SCN4A-related congenital myopathy and myasthenic syndrome were reviewed. This case exemplifies the utility of next generation sequencing in the diagnosis of undifferentiated muscle disease.
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Affiliation(s)
- Tina Yee-Ching Chan
- Kowloon West Cluster Laboratory Genetic Service, Chemical Pathology Laboratory, Department of Pathology, Princess Margaret Hospital, Hong Kong Special Administrative Region
| | - Ling-Yin Hung
- Kowloon West Cluster Laboratory Genetic Service, Chemical Pathology Laboratory, Department of Pathology, Princess Margaret Hospital, Hong Kong Special Administrative Region
| | - Tiffany Yan-Lok Lam
- Department of Medicine and Geriatrics, Princess Margaret Hospital, Hong Kong Special Administrative Region
| | - Bun Sheng
- Department of Medicine and Geriatrics, Princess Margaret Hospital, Hong Kong Special Administrative Region
| | - Frank Ying-Kit Leung
- Kowloon West Cluster Laboratory Genetic Service, Chemical Pathology Laboratory, Department of Pathology, Princess Margaret Hospital, Hong Kong Special Administrative Region
- Department of Pathology, Yan Chai Hospital, Hong Kong Special Administrative Region
| | - Hencher Han-Chih Lee
- Kowloon West Cluster Laboratory Genetic Service, Chemical Pathology Laboratory, Department of Pathology, Princess Margaret Hospital, Hong Kong Special Administrative Region
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9
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Cannon SC. Periodic paralysis. HANDBOOK OF CLINICAL NEUROLOGY 2024; 203:39-58. [PMID: 39174253 PMCID: PMC11556526 DOI: 10.1016/b978-0-323-90820-7.00002-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/24/2024]
Abstract
Periodic paralysis is a rare, dominantly inherited disorder of skeletal muscle in which episodic attacks of weakness are caused by a transient impairment of fiber excitability. Attacks of weakness are often elicited by characteristic environmental triggers, which were the basis for clinically delineating subtypes of periodic paralysis and are an important distinction for optimal disease management. All forms of familial periodic paralysis are caused by mutations of ion channels, often selectively expressed in skeletal muscle, that destabilize the resting potential. The missense mutations usually alter channel function through gain-of-function changes rather than producing a complete loss-of-function null. The knowledge of which channel gene harbors a variant, whether that variant is expected to (or known to) alter function, and how altered function impairs fiber excitability aides in the interpretation of patient signs and symptoms, the interpretation of gene test results, and how to optimize therapeutic intervention for symptom management and improve quality of life.
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Affiliation(s)
- Stephen C Cannon
- Departments of Physiology and of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States.
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10
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Mackels L, Servais L. The Importance of Early Treatment of Inherited Neuromuscular Conditions. J Neuromuscul Dis 2024; 11:253-274. [PMID: 38306060 DOI: 10.3233/jnd-230189] [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] [Indexed: 02/03/2024]
Abstract
There has been tremendous progress in treatment of neuromuscular diseases over the last 20 years, which has transformed the natural history of these severely debilitating conditions. Although the factors that determine the response to therapy are many and in some instance remain to be fully elucidated, early treatment clearly has a major impact on patient outcomes across a number of inherited neuromuscular conditions. To improve patient care and outcomes, clinicians should be aware of neuromuscular conditions that require prompt treatment initiation. This review describes data that underscore the importance of early treatment of children with inherited neuromuscular conditions with an emphasis on data resulting from newborn screening efforts.
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Affiliation(s)
- Laurane Mackels
- MDUK Oxford Neuromuscular Centre, Department of Paediatrics, University of Oxford, Oxford, United Kingdom
- Adult Neurology Department, Citadelle Hospital, Liège, Belgium
| | - Laurent Servais
- Neuromuscular Centre, Division of Paediatrics, University and University Hospital of Liège, Liège, Belgium
- MDUK Oxford Neuromuscular Centre, Department of Paediatrics, University of Oxford & NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
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11
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Matthews E, Palace J, Ramdas S, Sansone V, Tristani-Firouzi M, Vicart S, Willis T. Care Recommendations for the Investigation and Management of Children With Skeletal Muscle Channelopathies. Pediatr Neurol 2023; 145:102-111. [PMID: 37315339 DOI: 10.1016/j.pediatrneurol.2023.05.012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 05/12/2023] [Accepted: 05/14/2023] [Indexed: 06/16/2023]
Abstract
The field of pediatric skeletal muscle channelopathies has seen major new advances in terms of a wider understanding of clinical presentations and new phenotypes. Skeletal muscle channelopathies cause significant disability and even death in some of the newly described phenotypes. Despite this, there are virtually no data on the epidemiology and longitudinal natural history of these conditions or randomized controlled trial evidence of efficacy or tolerability of any treatment in children, and thus best practice care recommendations do not exist. Clinical history, and to a lesser extent examination, is key to eliciting symptoms and signs that indicate a differential diagnosis of muscle channelopathy. Normal routine investigations should not deter one from the diagnosis. Specialist neurophysiologic investigations have an additional role, but their availability should not delay genetic testing. New phenotypes are increasingly likely to be identified by next-generation sequencing panels. Many treatments or interventions for symptomatic patients are available, with anecdotal data to support their benefit, but we lack trial data on efficacy, safety, or superiority. This lack of trial data in turn can lead to hesitancy in prescribing among doctors or in accepting medication by parents. Holistic management addressing work, education, activity, and additional symptoms of pain and fatigue provides significant benefit. Preventable morbidity and sometimes mortality occurs if the diagnosis and therefore treatment is delayed. Advances in genetic sequencing technology and greater access to testing may help to refine recently identified phenotypes, including histology, as more cases are described. Randomized controlled treatment trials are required to inform best practice care recommendations. A holistic approach to management is essential and should not be overlooked. Good quality data on prevalence, health burden, and optimal treatment are urgently needed.
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Affiliation(s)
- Emma Matthews
- Department of Neurology, Atkinson-Morley Neuromuscular Centre, St George's University Hospitals NHS Foundation Trust, and Molecular and Clinical Sciences Research Institute, St George's University of London, London, UK.
| | - Jacqueline Palace
- Clinical Neurology, John Radcliffe Hospital, Oxford University Foundation Trust, Oxford, UK; Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Sithara Ramdas
- Department of Paediatrics, MDUK Neuromuscular Centre, University of Oxford, Oxford, UK; Department of Paediatric Neurology, John Radcliffe Hospital, Oxford, UK
| | - Valeria Sansone
- Neurorehabilitation Unit, Neuromuscular Omnicentre Clinical Center, Niguarda Hospital, University of Milan, Milan, Italy
| | - Martin Tristani-Firouzi
- Nora Eccles Harrison Cardiovascular Research and Training Institute and the Division of Paediatric Cardiology, University of Utah, Salt Lake City, Utah
| | - Savine Vicart
- Reference Centre for Neuromuscular Disorders, APHP, Institute of Myology, Pitié-Salpêtrière Hospital, Paris, France
| | - Tracey Willis
- Robert Jones and Agnes Hunt Orthopaedic Hospital, NHS Foundation Trust, Oswestry, England
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Vicino A, Brugnoni R, Maggi L. Diagnostics in skeletal muscle channelopathies. Expert Rev Mol Diagn 2023; 23:1175-1193. [PMID: 38009256 DOI: 10.1080/14737159.2023.2288258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Accepted: 11/22/2023] [Indexed: 11/28/2023]
Abstract
INTRODUCTION Skeletal muscle channelopathies (SMCs) are a heterogenous group of disorders, caused by mutations in skeletal ion channels leading to abnormal muscle excitability, resulting in either delayed muscle relaxation (myotonia) which characterizes non-dystrophic myotonias (NDMs), or membrane transient inactivation, causing episodic weakness, typical of periodic paralyses (PPs). AREAS COVERED SMCs include myotonia congenita, paramyotonia congenita, and sodium-channel myotonia among NDMs, and hyper-normokalemic, hypokalemic, or late-onset periodic paralyses among PPs. When suspecting an SMC, a structured diagnostic approach is required. Detailed personal and family history and clinical examination are essential, while neurophysiological tests should confirm myotonia and rule out alternative diagnosis. Moreover, specific electrodiagnostic studies are important to further define the phenotype of de novo cases and drive molecular analyses together with clinical data. Definite diagnosis is achieved through genetic testing, either with Sanger sequencing or multigene next-generation sequencing panel. In still unsolved patients, more advanced techniques, as exome-variant sequencing or whole-genome sequencing, may be considered in expert centers. EXPERT OPINION The diagnostic approach to SMC is still mainly based on clinical data; moreover, definite diagnosis is sometimes complicated by the difficulty to establish a proper genotype-phenotype correlation. Lastly, further studies are needed to allow the genetic characterization of unsolved patients.
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Affiliation(s)
- Alex Vicino
- Neurology IV Unit, Neuroimmunology and Neuromuscular Diseases, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
- Nerve-Muscle Unit, Neurology Service, Department of Clinical Neurosciences, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
| | - Raffaella Brugnoni
- Neurology IV Unit, Neuroimmunology and Neuromuscular Diseases, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Lorenzo Maggi
- Neurology IV Unit, Neuroimmunology and Neuromuscular Diseases, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
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13
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Mendpara V, Bethanabotla S, Yadav M, Kanisetti V, Singh G, Das A, Sahu S, Patel H. When Breathing Becomes a Challenge: A Case of Congenital Myasthenia Gravis in an Indian Neonate With a DOK-7 Gene Mutation. Cureus 2023; 15:e38842. [PMID: 37303354 PMCID: PMC10256249 DOI: 10.7759/cureus.38842] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/10/2023] [Indexed: 06/13/2023] Open
Abstract
A rare neuromuscular condition known as congenital myasthenia gravis (CMG) affects some people from birth or very soon after. It results in fatigue and muscle weakness because of genetic abnormalities that interfere with the neuromuscular junction's ability to function, where the nerves and muscles connect. Even among those who have the same genetic mutation, the severity of CMG symptoms might differ considerably. The most typical signs of CMG include eyelid drooping, breathing issues, muscle weakness and weariness, and difficulties swallowing. Clinical examinations, neurophysiologic tests, and genetic analyses are frequently combined to make the diagnosis of CMG. Although there is no known treatment for CMG, many patients may control their symptoms and lead relatively normal lives with the right care. A newborn with CMG due to a DOK-7 gene mutation is described in this article, along with its very early onset. The DOK-7 mutation is a rare variant in the Indian population that causes CMG and usually manifests as 'limb girdle' weakness. However, due to muscle weakness, the neonate in this case developed severe respiratory distress and later died despite rigorous life-saving measures.
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Affiliation(s)
- Vaidehi Mendpara
- Medicine and Surgery, Pediatrics, Government Medical College Surat, Surat, IND
| | | | - Megha Yadav
- Medicine and Surgery, Maharani Laxmi Bai Medical College, Jhansi, IND
| | | | - Gurpreet Singh
- Medicine, Government Medical College and Hospital, Amritsar, IND
| | - Abhirami Das
- Internal Medicine, Rajiv Gandhi Medical College, Thane, IND
| | - Sweta Sahu
- Surgery, Jagadguru Jayadeva Murugarajendra (JJM) Medical College, Davanagere, IND
| | - Hitesh Patel
- Pediatrics and Child Health, Government Medical College and Hospital, Surat, IND
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Corbett RJ, Ford LM, Raney NE, Grabowski JM, Ernst CW. Pig fetal skeletal muscle development is associated with genome-wide DNA hypomethylation and corresponding alterations in transcript and microRNA expression. Genome 2023; 66:68-79. [PMID: 36876850 DOI: 10.1139/gen-2022-0008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/07/2023]
Abstract
Fetal myogenesis represents a critical period of porcine skeletal muscle development and requires coordinated expression of thousands of genes. Epigenetic mechanisms, including DNA methylation, drive transcriptional regulation during development; however, these processes are understudied in developing porcine tissues. We performed bisulfite sequencing to assess DNA methylation in pig longissimus dorsi muscle at 41- and 70-days gestation (dg), as well as RNA- and small RNA-sequencing to identify coordinated changes in methylation and expression between myogenic stages. We identified 45 739 differentially methylated regions (DMRs) between stages, and the majority (N = 34 232) were hypomethylated at 70 versus 41 dg. Integration of methylation and transcriptomic data revealed strong associations between differential gene methylation and expression. Differential miRNA methylation was significantly negatively correlated with abundance, and dynamic expression of assayed miRNAs persisted postnatally. Motif analysis revealed significant enrichment of myogenic regulatory factor motifs among hypomethylated regions, suggesting that DNA hypomethylation may function to increase accessibility of muscle-specific transcription factors. We show that developmental DMRs are enriched for GWAS SNPs for muscle- and meat-related traits, demonstrating the potential for epigenetic processes to influence phenotypic diversity. Our results enhance understanding of DNA methylation dynamics of porcine myogenesis and reveal putative cis-regulatory elements governed by epigenetic processes.
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Affiliation(s)
- R J Corbett
- Genetics & Genome Sciences Graduate Program, Michigan State University, East Lansing, MI 48824, USA
| | - L M Ford
- Genetics & Genome Sciences Graduate Program, Michigan State University, East Lansing, MI 48824, USA
| | - N E Raney
- Department of Animal Science, Michigan State University, East Lansing, MI 48824, USA
| | - J M Grabowski
- Department of Animal Science, Michigan State University, East Lansing, MI 48824, USA
| | - C W Ernst
- Department of Animal Science, Michigan State University, East Lansing, MI 48824, USA
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15
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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: 54] [Impact Index Per Article: 27.0] [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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16
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Shibano M, Kubota T, Kokubun N, Miyaji Y, Kuriki H, Ito Y, Hamanoue H, Takahashi MP. Periodic paralysis due to cumulative effects of rare variants in SCN4A with small functional alterations. Muscle Nerve 2022; 66:757-761. [PMID: 36116128 DOI: 10.1002/mus.27725] [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: 01/23/2022] [Revised: 09/07/2022] [Accepted: 09/11/2022] [Indexed: 12/14/2022]
Abstract
INTRODUCTION/AIMS Mutations in the SCN4A gene encoding a voltage-gated sodium channel (Nav1.4) cause hyperkalemic periodic paralysis (HyperPP) and hypokalemic periodic paralysis (HypoPP). Typically, both HyperPP and HypoPP are considered as monogenic disorders caused by a missense mutation with a large functional effect. However, a few cases with atypical periodic paralysis phenotype have been caused by multiple mutations in ion-channel genes expressed in skeletal muscles. In this study we investigated the underlying pathogenic mechanisms in such cases. METHODS We clinically assessed two families: proband 1 with HyperPP and proband 2 with atypical periodic paralysis with hypokalemia. Genetic analyses were performed by next-generation sequencing and conventional Sanger sequencing, followed by electrophysiological analyses of the mutant Nav1.4 channels expressed in human embryonic kidney 293T (HEK293T) cells using the whole-cell patch-clamp technique. RESULTS In proband 1, K880del was identified in the SCN4A gene. In proband 2, K880del and a novel mutation, R1639H, were identified in the same allele of the SCN4A gene. Functional analyses revealed that the K880del in SCN4A has a weak functional effect on hNav1.4, increasing the excitability of the sarcolemma, which could represent a potential pathogenic factor. Although R1639H alone did not reveal functional changes strong enough to be pathogenic, Nav1.4 with both K880del and R1639H showed enhanced activation compared with K880del alone, indicating that R1639H may modify the hNav1.4 channel function. DISCUSSION A cumulative effect of variants with small functional alterations may be considered as the underpinning oligogenic pathogenic mechanisms for the unusual phenotype of periodic paralysis.
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Affiliation(s)
- Maki Shibano
- Clinical Neurophysiology, Department of Clinical Laboratory and Biomedical Sciences, Division of Health Sciences, Osaka University Graduate School of Medicine, Suita, Japan
| | - Tomoya Kubota
- Clinical Neurophysiology, Department of Clinical Laboratory and Biomedical Sciences, Division of Health Sciences, Osaka University Graduate School of Medicine, Suita, Japan
| | - Norito Kokubun
- Department of Neurology, Dokkyo Medical University, Shimotsuga, Japan
| | - Yosuke Miyaji
- Department of Neurology and Stroke Medicine, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Hiroko Kuriki
- Department of Clinical Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Yuzuru Ito
- Department of Endocrinology and Metabolism, Yokohama City University Medical Center, Yokohama, Japan
| | - Haruka Hamanoue
- Department of Clinical Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Masanori P Takahashi
- Clinical Neurophysiology, Department of Clinical Laboratory and Biomedical Sciences, Division of Health Sciences, Osaka University Graduate School of Medicine, Suita, Japan
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17
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Pepke ML, Kvalnes T, Lundregan S, Boner W, Monaghan P, Saether BE, Jensen H, Ringsby TH. Genetic architecture and heritability of early-life telomere length in a wild passerine. Mol Ecol 2022; 31:6360-6381. [PMID: 34825754 DOI: 10.1111/mec.16288] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 10/01/2021] [Accepted: 11/09/2021] [Indexed: 01/31/2023]
Abstract
Early-life telomere length (TL) is associated with fitness in a range of organisms. Little is known about the genetic basis of variation in TL in wild animal populations, but to understand the evolutionary and ecological significance of TL it is important to quantify the relative importance of genetic and environmental variation in TL. In this study, we measured TL in 2746 house sparrow nestlings sampled across 20 years and used an animal model to show that there is a small heritable component of early-life TL (h2 = 0.04). Variation in TL among individuals was mainly driven by environmental (annual) variance, but also brood and parental effects. Parent-offspring regressions showed a large maternal inheritance component in TL ( h maternal 2 = 0.44), but no paternal inheritance. We did not find evidence for a negative genetic correlation underlying the observed negative phenotypic correlation between TL and structural body size. Thus, TL may evolve independently of body size and the negative phenotypic correlation is likely to be caused by nongenetic environmental effects. We further used genome-wide association analysis to identify genomic regions associated with TL variation. We identified several putative genes underlying TL variation; these have been inferred to be involved in oxidative stress, cellular growth, skeletal development, cell differentiation and tumorigenesis in other species. Together, our results show that TL has a low heritability and is a polygenic trait strongly affected by environmental conditions in a free-living bird.
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Affiliation(s)
- Michael Le Pepke
- Department of Biology, Centre for Biodiversity Dynamics (CBD), Norwegian University of Science and Technology (NTNU), Trondheim, Norway
| | - Thomas Kvalnes
- Department of Biology, Centre for Biodiversity Dynamics (CBD), Norwegian University of Science and Technology (NTNU), Trondheim, Norway
| | - Sarah Lundregan
- Department of Biology, Centre for Biodiversity Dynamics (CBD), Norwegian University of Science and Technology (NTNU), Trondheim, Norway
| | - Winnie Boner
- Institute of Biodiversity, Animal Health and Comparative Medicine (IBAHCM), University of Glasgow, Glasgow, UK
| | - Pat Monaghan
- Institute of Biodiversity, Animal Health and Comparative Medicine (IBAHCM), University of Glasgow, Glasgow, UK
| | - Bernt-Erik Saether
- Department of Biology, Centre for Biodiversity Dynamics (CBD), Norwegian University of Science and Technology (NTNU), Trondheim, Norway
| | - Henrik Jensen
- Department of Biology, Centre for Biodiversity Dynamics (CBD), Norwegian University of Science and Technology (NTNU), Trondheim, Norway
| | - Thor Harald Ringsby
- Department of Biology, Centre for Biodiversity Dynamics (CBD), Norwegian University of Science and Technology (NTNU), Trondheim, Norway
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18
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Suetterlin KJ, Männikkö R, Matthews E, Greensmith L, Hanna MG, Bostock H, Tan SV. Excitability properties of mouse and human skeletal muscle fibres compared by muscle velocity recovery cycles. Neuromuscul Disord 2022; 32:347-357. [PMID: 35339342 PMCID: PMC7614892 DOI: 10.1016/j.nmd.2022.02.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2021] [Revised: 01/27/2022] [Accepted: 02/22/2022] [Indexed: 11/21/2022]
Abstract
Mouse models of skeletal muscle channelopathies are not phenocopies of human disease. In some cases (e.g. Myotonia Congenita) the phenotype is much more severe, whilst in others (e.g. Hypokalaemic periodic paralysis) rodent physiology is protective. This suggests a species' difference in muscle excitability properties. In humans these can be measured indirectly by the post-impulse changes in conduction velocity, using Muscle Velocity Recovery Cycles (MVRCs). We performed MVRCs in mice and compared their muscle excitability properties with humans. Mouse Tibialis Anterior MVRCs (n = 70) have only one phase of supernormality (increased conduction velocity), which is smaller in magnitude (p = 9 × 10-21), and shorter in duration (p = 3 × 10-24) than human (n = 26). This abbreviated supernormality is followed by a period of late subnormality (reduced velocity) in mice, which overlaps in time with the late supernormality seen in human MVRCs. The period of late subnormality suggests increased t-tubule Na+/K+-pump activity. The subnormal phase in mice was converted to supernormality by blocking ClC-1 chloride channels, suggesting relatively higher chloride conductance in skeletal muscle. Our findings help explain discrepancies in phenotype between mice and humans with skeletal muscle channelopathies and potentially other neuromuscular disorders. MVRCs are a valuable new tool to compare in vivo muscle membrane properties between species and will allow further dissection of the molecular mechanisms regulating muscle excitability.
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Affiliation(s)
- K J Suetterlin
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, United Kingdom; AGE Research Group, NIHR Newcastle Biomedical Research Centre, Newcastle upon Tyne Hospitals NHS Foundation Trust and Newcastle University, Newcastle upon Tyne, United Kingdom.
| | - R Männikkö
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, United Kingdom
| | - E Matthews
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, United Kingdom; Atkinson Morley Neuromuscular Centre, Department of Neurology, St Georges University Hospitals NHS Foundation Trust, London, United Kingdom
| | - L Greensmith
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, United Kingdom
| | - M G Hanna
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, United Kingdom
| | - H Bostock
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, United Kingdom
| | - S V Tan
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, United Kingdom; Department of Neurology and Clinical Neurophysiology, Guy's & St Thomas' NHS Foundation Trust and Institute of Psychiatry, Psychology & Neuroscience, Division of Neuroscience, King's College London, United Kingdom
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19
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Berghold VM, Koko M, Berutti R, Plecko B. Case report: Novel SCN4A variant associated with a severe congenital myasthenic syndrome/myopathy phenotype. Front Pediatr 2022; 10:944784. [PMID: 36090556 PMCID: PMC9462513 DOI: 10.3389/fped.2022.944784] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/15/2022] [Accepted: 08/01/2022] [Indexed: 11/13/2022] Open
Abstract
We present a now 18-year-old female patient with a severe congenital myopathy phenotype, originally diagnosed as mitochondrial myopathy, however later revealed to constitute a SCN4A-related myopathy based on genetic testing. After birth, floppiness, bradycardia and respiratory insufficiency ensued, and moderately reduced mitochondrial complex I activity was found in muscle tissue (tested at 3 weeks and 3 years of age, respectively). She was treated with riboflavin, carnitine, creatine and a ketogenic diet. At the age of 13 years, whole exome sequencing challenged the initial diagnosis by identifying two (compound heterozygous) SCN4A variants affecting the highly conserved voltage sensor and pore regions of the voltage-gated sodium channel NaV1.4: a known pathogenic loss of function (LOF) variant [c.4360C>T; p.(Arg1454Trp)] and a novel variant of uncertain significance [c.3615C>G; p.(Asn1205Lys)]. For this novel variant, a LOF effect was predicted by in silico, clinical and functional evidence from paralog human sodium channels, and the variant was accordingly classified as likely pathogenic. The patient's phenotype is in line with the few published cases of autosomal recessive SCN4A-related myopathy. There was limited benefit from treatment with salbutamol and acetazolamide, while pyridostigmine caused side effects at a minor dose. This report highlights the importance of genetic testing in severe myopathies particularly in regard to treatment options and the value of paralog information in evaluating ion channel variations.
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Affiliation(s)
- Veronika M Berghold
- Department of Pediatrics and Adolescent Medicine, Division of General Pediatrics, Medical University of Graz, Graz, Austria
| | - Mahmoud Koko
- Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Riccardo Berutti
- Institute of Human Genetics, University Hospital Rechts der Isar, Technical University of Munich, Munich, Germany.,Institute of Neurogenomics, Helmholtz Center Munich, German Research Center for Environmental Health, Neuherberg, Germany
| | - Barbara Plecko
- Department of Pediatrics and Adolescent Medicine, Division of General Pediatrics, Medical University of Graz, Graz, Austria
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20
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Nicole S, Lory P. New Challenges Resulting From the Loss of Function of Na v1.4 in Neuromuscular Diseases. Front Pharmacol 2021; 12:751095. [PMID: 34671263 PMCID: PMC8521073 DOI: 10.3389/fphar.2021.751095] [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] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Accepted: 09/16/2021] [Indexed: 11/13/2022] Open
Abstract
The voltage-gated sodium channel Nav1.4 is a major actor in the excitability of skeletal myofibers, driving the muscle force in response to nerve stimulation. Supporting further this key role, mutations in SCN4A, the gene encoding the pore-forming α subunit of Nav1.4, are responsible for a clinical spectrum of human diseases ranging from muscle stiffness (sodium channel myotonia, SCM) to muscle weakness. For years, only dominantly-inherited diseases resulting from Nav1.4 gain of function (GoF) were known, i.e., non-dystrophic myotonia (delayed muscle relaxation due to myofiber hyperexcitability), paramyotonia congenita and hyperkalemic or hypokalemic periodic paralyses (episodic flaccid muscle weakness due to transient myofiber hypoexcitability). These last 5 years, SCN4A mutations inducing Nav1.4 loss of function (LoF) were identified as the cause of dominantly and recessively-inherited disorders with muscle weakness: periodic paralyses with hypokalemic attacks, congenital myasthenic syndromes and congenital myopathies. We propose to name this clinical spectrum sodium channel weakness (SCW) as the mirror of SCM. Nav1.4 LoF as a cause of permanent muscle weakness was quite unexpected as the Na+ current density in the sarcolemma is large, securing the ability to generate and propagate muscle action potentials. The properties of SCN4A LoF mutations are well documented at the channel level in cellular electrophysiological studies However, much less is known about the functional consequences of Nav1.4 LoF in skeletal myofibers with no available pertinent cell or animal models. Regarding the therapeutic issues for Nav1.4 channelopathies, former efforts were aimed at developing subtype-selective Nav channel antagonists to block myofiber hyperexcitability. Non-selective, Nav channel blockers are clinically efficient in SCM and paramyotonia congenita, whereas patient education and carbonic anhydrase inhibitors are helpful to prevent attacks in periodic paralyses. Developing therapeutic tools able to counteract Nav1.4 LoF in skeletal muscles is then a new challenge in the field of Nav channelopathies. Here, we review the current knowledge regarding Nav1.4 LoF and discuss the possible therapeutic strategies to be developed in order to improve muscle force in SCW.
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Affiliation(s)
- Sophie Nicole
- Institut de Génomique Fonctionnelle (IGF), Université de Montpellier, CNRS, INSERM, Montpellier, France.,LabEx 'Ion Channel Science and Therapeutics (ICST), Montpellier, France
| | - Philippe Lory
- Institut de Génomique Fonctionnelle (IGF), Université de Montpellier, CNRS, INSERM, Montpellier, France.,LabEx 'Ion Channel Science and Therapeutics (ICST), Montpellier, France
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21
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Maggi L, Bonanno S, Altamura C, Desaphy JF. Ion Channel Gene Mutations Causing Skeletal Muscle Disorders: Pathomechanisms and Opportunities for Therapy. Cells 2021; 10:cells10061521. [PMID: 34208776 PMCID: PMC8234207 DOI: 10.3390/cells10061521] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 06/03/2021] [Accepted: 06/10/2021] [Indexed: 02/06/2023] Open
Abstract
Skeletal muscle ion channelopathies (SMICs) are a large heterogeneous group of rare genetic disorders caused by mutations in genes encoding ion channel subunits in the skeletal muscle mainly characterized by myotonia or periodic paralysis, potentially resulting in long-term disabilities. However, with the development of new molecular technologies, new genes and new phenotypes, including progressive myopathies, have been recently discovered, markedly increasing the complexity in the field. In this regard, new advances in SMICs show a less conventional role of ion channels in muscle cell division, proliferation, differentiation, and survival. Hence, SMICs represent an expanding and exciting field. Here, we review current knowledge of SMICs, with a description of their clinical phenotypes, cellular and molecular pathomechanisms, and available treatments.
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Affiliation(s)
- Lorenzo Maggi
- Neuroimmunology and Neuromuscular Disorders Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, 20133 Milan, Italy;
- Correspondence:
| | - Silvia Bonanno
- Neuroimmunology and Neuromuscular Disorders Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, 20133 Milan, Italy;
| | - Concetta Altamura
- Department of Biomedical Sciences and Human Oncology, School of Medicine, University of Bari Aldo Moro, 70124 Bari, Italy; (C.A.); (J.-F.D.)
| | - Jean-François Desaphy
- Department of Biomedical Sciences and Human Oncology, School of Medicine, University of Bari Aldo Moro, 70124 Bari, Italy; (C.A.); (J.-F.D.)
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22
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Alsallum MS, Alshareef A, Abuzinadah AR, Bamaga AK, Dallol A. A novel DOK7 mutation causing congenital myasthenic syndrome with limb-girdle weakness: case series of three family members. Heliyon 2021; 7:e06869. [PMID: 34027146 PMCID: PMC8120944 DOI: 10.1016/j.heliyon.2021.e06869] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 11/05/2020] [Accepted: 04/16/2021] [Indexed: 11/12/2022] Open
Abstract
Congenital myasthenia syndrome (CMS) is a group of heterogeneous diseases affecting the neuromuscular endplate. CMS has a considerably different phenotypic presentations, with the onset time ranging from early infancy to late adulthood. Here, we report a case of a CMS due to a new DOK7 mutation in a 28-year-old man and two of his sisters, who have a pure limb-girdle weakness. DOK7 CMS has a varying presentation. Typically, the onset occurs in childhood with ptosis, bulbar symptoms, difficulty walking, weakness, and gait abnormality. This case sheds light on a novel DOK7 gene mutation with a unique presentation of CMS and provides insight into its unique phenotypic presentation.
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Affiliation(s)
- Mohammed S Alsallum
- Neurology Resident, King Abdulaziz University Hospital, P.O. Box: 80200, 21589, Jeddah, Saudi Arabia
| | - Aysha Alshareef
- King Abdulaziz University, Faculty of Medicine, King Abdulaziz University Hospital, Internal Medicine Department, Neurology Division, P.O. Box: 80200, 21589, Jeddah, Saudi Arabia.,Neuromuscular Unit, King Fahad Medical Research Center, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Ahmad R Abuzinadah
- King Abdulaziz University, Faculty of Medicine, King Abdulaziz University Hospital, Internal Medicine Department, Neurology Division, P.O. Box: 80200, 21589, Jeddah, Saudi Arabia.,Neuromuscular Unit, King Fahad Medical Research Center, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Ahmed K Bamaga
- Neuromuscular Unit, King Fahad Medical Research Center, King Abdulaziz University, Jeddah, Saudi Arabia.,King Abdulaziz University, Faculty of Medicine, King Abdulaziz University Hospital, Pediatric Department, Neurology Division, P.O. Box: 80200, 21589, Jeddah, Saudi Arabia
| | - Ashraf Dallol
- Center of Excellence in Genomic Medicine Research and Faculty of Applied Medical Sciences, King Abdulaziz University, P.O. Box: 80200, 21589, Saudi Arabia
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23
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Mantegazza M, Cestèle S, Catterall WA. Sodium channelopathies of skeletal muscle and brain. Physiol Rev 2021; 101:1633-1689. [PMID: 33769100 DOI: 10.1152/physrev.00025.2020] [Citation(s) in RCA: 59] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Voltage-gated sodium channels initiate action potentials in nerve, skeletal muscle, and other electrically excitable cells. Mutations in them cause a wide range of diseases. These channelopathy mutations affect every aspect of sodium channel function, including voltage sensing, voltage-dependent activation, ion conductance, fast and slow inactivation, and both biosynthesis and assembly. Mutations that cause different forms of periodic paralysis in skeletal muscle were discovered first and have provided a template for understanding structure, function, and pathophysiology at the molecular level. More recent work has revealed multiple sodium channelopathies in the brain. Here we review the well-characterized genetics and pathophysiology of the periodic paralyses of skeletal muscle and then use this information as a foundation for advancing our understanding of mutations in the structurally homologous α-subunits of brain sodium channels that cause epilepsy, migraine, autism, and related comorbidities. We include studies based on molecular and structural biology, cell biology and physiology, pharmacology, and mouse genetics. Our review reveals unexpected connections among these different types of sodium channelopathies.
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Affiliation(s)
- Massimo Mantegazza
- Université Cote d'Azur, Valbonne-Sophia Antipolis, France.,CNRS UMR7275, Institut de Pharmacologie Moléculaire et Cellulaire, Valbonne-Sophia Antipolis, France.,INSERM, Valbonne-Sophia Antipolis, France
| | - Sandrine Cestèle
- Université Cote d'Azur, Valbonne-Sophia Antipolis, France.,CNRS UMR7275, Institut de Pharmacologie Moléculaire et Cellulaire, Valbonne-Sophia Antipolis, France
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24
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Ademuwagun IA, Rotimi SO, Syrbe S, Ajamma YU, Adebiyi E. Voltage Gated Sodium Channel Genes in Epilepsy: Mutations, Functional Studies, and Treatment Dimensions. Front Neurol 2021; 12:600050. [PMID: 33841294 PMCID: PMC8024648 DOI: 10.3389/fneur.2021.600050] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Accepted: 03/01/2021] [Indexed: 12/19/2022] Open
Abstract
Genetic epilepsy occurs as a result of mutations in either a single gene or an interplay of different genes. These mutations have been detected in ion channel and non-ion channel genes. A noteworthy class of ion channel genes are the voltage gated sodium channels (VGSCs) that play key roles in the depolarization phase of action potentials in neurons. Of huge significance are SCN1A, SCN1B, SCN2A, SCN3A, and SCN8A genes that are highly expressed in the brain. Genomic studies have revealed inherited and de novo mutations in sodium channels that are linked to different forms of epilepsies. Due to the high frequency of sodium channel mutations in epilepsy, this review discusses the pathogenic mutations in the sodium channel genes that lead to epilepsy. In addition, it explores the functional studies on some known mutations and the clinical significance of VGSC mutations in the medical management of epilepsy. The understanding of these channel mutations may serve as a strong guide in making effective treatment decisions in patient management.
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Affiliation(s)
- Ibitayo Abigail Ademuwagun
- Covenant University Bioinformatics Research, Covenant University, Ota, Nigeria
- Department of Biochemistry, Covenant University, Ota, Nigeria
| | - Solomon Oladapo Rotimi
- Covenant University Bioinformatics Research, Covenant University, Ota, Nigeria
- Department of Biochemistry, Covenant University, Ota, Nigeria
| | - Steffen Syrbe
- Clinic for Pediatric and Adolescent Medicine, Heidelberg University, Heidelberg, Germany
| | | | - Ezekiel Adebiyi
- Covenant University Bioinformatics Research, Covenant University, Ota, Nigeria
- Department of Computer and Information Sciences, Covenant University, Ota, Nigeria
- Division of Applied Bioinformatics, German Cancer Research Center (DKFZ), Heidelberg, Germany
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25
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Desaphy JF, Altamura C, Vicart S, Fontaine B. Targeted Therapies for Skeletal Muscle Ion Channelopathies: Systematic Review and Steps Towards Precision Medicine. J Neuromuscul Dis 2021; 8:357-381. [PMID: 33325393 PMCID: PMC8203248 DOI: 10.3233/jnd-200582] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
BACKGROUND Skeletal muscle ion channelopathies include non-dystrophic myotonias (NDM), periodic paralyses (PP), congenital myasthenic syndrome, and recently identified congenital myopathies. The treatment of these diseases is mainly symptomatic, aimed at reducing muscle excitability in NDM or modifying triggers of attacks in PP. OBJECTIVE This systematic review collected the evidences regarding effects of pharmacological treatment on muscle ion channelopathies, focusing on the possible link between treatments and genetic background. METHODS We searched databases for randomized clinical trials (RCT) and other human studies reporting pharmacological treatments. Preclinical studies were considered to gain further information regarding mutation-dependent drug effects. All steps were performed by two independent investigators, while two others critically reviewed the entire process. RESULTS For NMD, RCT showed therapeutic benefits of mexiletine and lamotrigine, while other human studies suggest some efficacy of various sodium channel blockers and of the carbonic anhydrase inhibitor (CAI) acetazolamide. Preclinical studies suggest that mutations may alter sensitivity of the channel to sodium channel blockers in vitro, which has been translated to humans in some cases. For hyperkalemic and hypokalemic PP, RCT showed efficacy of the CAI dichlorphenamide in preventing paralysis. However, hypokalemic PP patients carrying sodium channel mutations may have fewer benefits from CAI compared to those carrying calcium channel mutations. Few data are available for treatment of congenital myopathies. CONCLUSIONS These studies provided limited information about the response to treatments of individual mutations or groups of mutations. A major effort is needed to perform human studies for designing a mutation-driven precision medicine in muscle ion channelopathies.
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Affiliation(s)
- Jean-François Desaphy
- Department of Biomedical Sciences and Human Oncology, School of Medicine, University of Bari Aldo Moro, Bari, Italy
| | - Concetta Altamura
- Department of Biomedical Sciences and Human Oncology, School of Medicine, University of Bari Aldo Moro, Bari, Italy
| | - Savine Vicart
- Sorbonne Université, INSERM, Assistance Publique Hôpitaux de Paris, Centre de Recherche en Myologie-UMR 974, Reference center in neuro-muscular channelopathies, Institute of Myology, Hôpital Universitaire Pitié-Salpêtrière, Paris, France
| | - Bertrand Fontaine
- Sorbonne Université, INSERM, Assistance Publique Hôpitaux de Paris, Centre de Recherche en Myologie-UMR 974, Reference center in neuro-muscular channelopathies, Institute of Myology, Hôpital Universitaire Pitié-Salpêtrière, Paris, France
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26
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Stunnenberg BC, LoRusso S, Arnold WD, Barohn RJ, Cannon SC, Fontaine B, Griggs RC, Hanna MG, Matthews E, Meola G, Sansone VA, Trivedi JR, van Engelen BG, Vicart S, Statland JM. Guidelines on clinical presentation and management of nondystrophic myotonias. Muscle Nerve 2020; 62:430-444. [PMID: 32270509 PMCID: PMC8117169 DOI: 10.1002/mus.26887] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 04/01/2020] [Accepted: 04/04/2020] [Indexed: 12/26/2022]
Abstract
The nondystrophic myotonias are rare muscle hyperexcitability disorders caused by gain-of-function mutations in the SCN4A gene or loss-of-function mutations in the CLCN1 gene. Clinically, they are characterized by myotonia, defined as delayed muscle relaxation after voluntary contraction, which leads to symptoms of muscle stiffness, pain, fatigue, and weakness. Diagnosis is based on history and examination findings, the presence of electrical myotonia on electromyography, and genetic confirmation. In the absence of genetic confirmation, the diagnosis is supported by detailed electrophysiological testing, exclusion of other related disorders, and analysis of a variant of uncertain significance if present. Symptomatic treatment with a sodium channel blocker, such as mexiletine, is usually the first step in management, as well as educating patients about potential anesthetic complications.
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Affiliation(s)
- Bas C. Stunnenberg
- Department of Neurology, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Samantha LoRusso
- Department of Neurology, Ohio State University Wexner Medical Center, Columbus, Ohio
| | - W. David Arnold
- Department of Neurology, Ohio State University Wexner Medical Center, Columbus, Ohio
| | - Richard J. Barohn
- Department of Neurology, University of Kansas Medical Center, Kansas City, Kansas
| | - Stephen C. Cannon
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California
| | - Bertrand Fontaine
- Assistance Publique-Hôpitaix de Paris, Sorbonne Université, INSERM, Service of Neuro-Myology and UMR 974, Institute of Myology, University Hospital Pitié-Salpêtrière, Paris, France
| | - Robert C. Griggs
- Department of Neurology, University of Rochester, Rochester, New York
| | - Michael G. Hanna
- MRC Centre for Neuromuscular Diseases, Department of Neuromuscular diseases, UCL Queen Square Institute of Neurology, United Kingdom
| | - Emma Matthews
- MRC Centre for Neuromuscular Diseases, Department of Neuromuscular diseases, UCL Queen Square Institute of Neurology, United Kingdom
| | - Giovanni Meola
- Department of Neurorehabilitation Sciences, Casa Cura Policlinico, Milan, Italy
- Department of Biomedical Sciences for Health, University of Milan, Milan, Italy
| | - Valeria A. Sansone
- Department of Biomedical Sciences for Health, University of Milan, Milan, Italy
- Neurorehabilitation Unit, University of Milan, NEuroMuscular Omnicentre (NEMO), Fondazione Serena Onlus, Milan, Italy
| | - Jaya R. Trivedi
- Department of Neurology and Neurotherapeutics, UT Southwestern Medical Center, Dallas, Texas
| | | | - Savine Vicart
- Assistance Publique-Hôpitaix de Paris, Sorbonne Université, INSERM, Service of Neuro-Myology and UMR 974, Institute of Myology, University Hospital Pitié-Salpêtrière, Paris, France
| | - Jeffrey M. Statland
- Department of Neurology, University of Kansas Medical Center, Kansas City, Kansas
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27
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Witty DR, Alvaro G, Derjean D, Giblin GMP, Gunn K, Large C, Macpherson DT, Morisset V, Owen D, Palmer J, Rugiero F, Tate S, Hinckley CA, Naik H. Discovery of Vixotrigine: A Novel Use-Dependent Sodium Channel Blocker for the Treatment of Trigeminal Neuralgia. ACS Med Chem Lett 2020; 11:1678-1687. [PMID: 32945812 PMCID: PMC7488392 DOI: 10.1021/acsmedchemlett.0c00263] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2020] [Accepted: 07/16/2020] [Indexed: 12/19/2022] Open
Abstract
Drugs that block voltage-gated sodium channels (NaVs) have utility in treating conditions including pain, epilepsy, and cardiac arrhythmias and as anesthetics (Lancet Neurol.20109413424; Expert Opin. Ther. Pat.201020755779). The identification of compounds with improved efficacy and safety is a key aim for the discovery of improved NaV blocking drugs (Comprehensive Medicinal Chemistry III; (Elsevier, 2017; pp 131-175). We report the identification of a novel class of brain penetrant and voltage-gated sodium channel blockers, leading to the discovery of vixotrigine, a use-dependent sodium channel blocker with activity in in vivo models of pain. Vixotrigine has excellent physiocochemical properties for drug development, and both preclinical and clinical data support a safety profile suitable for potential use in neuropathic pain and other conditions. It has shown efficacy in a Phase II study for pain associated with trigeminal neuralgia.
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Affiliation(s)
- David R. Witty
- Convergence
Pharmaceuticals Ltd., a Biogen Company, Babraham Research
Campus, Cambridge CB22 3AT,
U.K.
| | - Giuseppe Alvaro
- Convergence
Pharmaceuticals Ltd., a Biogen Company, Babraham Research
Campus, Cambridge CB22 3AT,
U.K.
| | - Dominique Derjean
- Convergence
Pharmaceuticals Ltd., a Biogen Company, Babraham Research
Campus, Cambridge CB22 3AT,
U.K.
| | - Gerard M. P. Giblin
- Convergence
Pharmaceuticals Ltd., a Biogen Company, Babraham Research
Campus, Cambridge CB22 3AT,
U.K.
| | - Kevin Gunn
- Convergence
Pharmaceuticals Ltd., a Biogen Company, Babraham Research
Campus, Cambridge CB22 3AT,
U.K.
| | - Charles Large
- Convergence
Pharmaceuticals Ltd., a Biogen Company, Babraham Research
Campus, Cambridge CB22 3AT,
U.K.
| | - David T. Macpherson
- Convergence
Pharmaceuticals Ltd., a Biogen Company, Babraham Research
Campus, Cambridge CB22 3AT,
U.K.
| | - Valerie Morisset
- Convergence
Pharmaceuticals Ltd., a Biogen Company, Babraham Research
Campus, Cambridge CB22 3AT,
U.K.
| | - Davina Owen
- Convergence
Pharmaceuticals Ltd., a Biogen Company, Babraham Research
Campus, Cambridge CB22 3AT,
U.K.
| | - Joanne Palmer
- Convergence
Pharmaceuticals Ltd., a Biogen Company, Babraham Research
Campus, Cambridge CB22 3AT,
U.K.
| | - Francois Rugiero
- Convergence
Pharmaceuticals Ltd., a Biogen Company, Babraham Research
Campus, Cambridge CB22 3AT,
U.K.
| | - Simon Tate
- Convergence
Pharmaceuticals Ltd., a Biogen Company, Babraham Research
Campus, Cambridge CB22 3AT,
U.K.
| | | | - Himanshu Naik
- Biogen
Inc., 225 Binney Street, Cambridge, Massachusetts 02142,
United States
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28
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Di L, Chen H, Lu Y, Selcen D, Engel AG, Da Y, Shen XM. Determinants of the repetitive-CMAP occurrence and therapy efficacy in slow-channel myasthenia. Neurology 2020; 95:e2781-e2793. [PMID: 32907971 DOI: 10.1212/wnl.0000000000010734] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2019] [Accepted: 06/22/2020] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVE To find determinants of the occurrence of repetitive compound muscle action potential (R-CMAP) and to assess the efficacy of channel blocker therapy in slow-channel congenital myasthenic syndrome (SCCMS). METHODS Neurologic examination, EMG study, laboratory test, muscle biopsy, and next-generation and Sanger sequencing; literature review of reported patients with SCCMS, including EMG, kinetics of mutant acetylcholine receptors (AChRs), and response to therapy; and simulation of the decay phase of endplate potential (EPP) were performed. RESULTS Three newly characterized and 57 reported patients with SCCMS with mutations of AChR subunits were included. In patients with R-CMAP, the length of channel opening bursts of mutant AChR was increased 8.68 ± 2.82 (mean ± SD)-fold compared to wild-type; in patients without R-CMAP, the length was increased 3.84 ± 0.65-fold (95% confidence interval 3.18-6.50, p = 0.000014). The EPP amplitude after refractory period of action potential in muscle fiber is above the threshold in patients with R-CMAP but below the threshold in patients without R-CMAP. In patients with good results from channel blocker therapy, treatment was initiated 11.60 ± 5.17 years after onset of symptoms; in patients with no to moderate benefit from channel blocker therapy, treatment was initiated 30.70 ± 12.72 years after onset (95% confidence interval -28.57 to -9.63, p = 0.00089). CONCLUSIONS In SCCMS, the R-CMAP occurrence is related to the extent of prolongation of the opening episodes of mutant AChR channel. Channel blocker treatment is more effective the sooner it is started after the onset of symptoms. CLASSIFICATION OF EVIDENCE This study provides Class IV evidence that channel blocker therapy in patients with SCCMS improves symptoms.
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Affiliation(s)
- Li Di
- From the Department of Neurology (L.D., H.C., Y.L., Y.D.), Xuanwu Hospital, Capital Medical University, Beijing, China; and Department of Neurology and Neuromuscular Research Laboratory (L.D., D.S., A.G.E., X.-M.S.), Mayo Clinic, Rochester, MN
| | - Hai Chen
- From the Department of Neurology (L.D., H.C., Y.L., Y.D.), Xuanwu Hospital, Capital Medical University, Beijing, China; and Department of Neurology and Neuromuscular Research Laboratory (L.D., D.S., A.G.E., X.-M.S.), Mayo Clinic, Rochester, MN
| | - Yan Lu
- From the Department of Neurology (L.D., H.C., Y.L., Y.D.), Xuanwu Hospital, Capital Medical University, Beijing, China; and Department of Neurology and Neuromuscular Research Laboratory (L.D., D.S., A.G.E., X.-M.S.), Mayo Clinic, Rochester, MN
| | - Duygu Selcen
- From the Department of Neurology (L.D., H.C., Y.L., Y.D.), Xuanwu Hospital, Capital Medical University, Beijing, China; and Department of Neurology and Neuromuscular Research Laboratory (L.D., D.S., A.G.E., X.-M.S.), Mayo Clinic, Rochester, MN
| | - Andrew G Engel
- From the Department of Neurology (L.D., H.C., Y.L., Y.D.), Xuanwu Hospital, Capital Medical University, Beijing, China; and Department of Neurology and Neuromuscular Research Laboratory (L.D., D.S., A.G.E., X.-M.S.), Mayo Clinic, Rochester, MN
| | - Yuwei Da
- From the Department of Neurology (L.D., H.C., Y.L., Y.D.), Xuanwu Hospital, Capital Medical University, Beijing, China; and Department of Neurology and Neuromuscular Research Laboratory (L.D., D.S., A.G.E., X.-M.S.), Mayo Clinic, Rochester, MN.
| | - Xin-Ming Shen
- From the Department of Neurology (L.D., H.C., Y.L., Y.D.), Xuanwu Hospital, Capital Medical University, Beijing, China; and Department of Neurology and Neuromuscular Research Laboratory (L.D., D.S., A.G.E., X.-M.S.), Mayo Clinic, Rochester, MN.
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29
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Mu Y, Li W, Wei Z, He L, Zhang W, Chen X. Transcriptome analysis reveals molecular strategies in gills and heart of large yellow croaker (Larimichthys crocea) under hypoxia stress. FISH & SHELLFISH IMMUNOLOGY 2020; 104:304-313. [PMID: 32544557 DOI: 10.1016/j.fsi.2020.06.028] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Revised: 06/07/2020] [Accepted: 06/12/2020] [Indexed: 06/11/2023]
Abstract
The gills and heart are two major targets of hypoxia in fish. However, the molecular responses in fish gills and heart to hypoxia challenge remain unclear. Here, RNA-Seq technology was used to study the gene expression profiles in gills and heart of large yellow croaker (Larimichthys crocea) at 6, 24, and 48 h after hypoxia stress. A total of 1,546 and 2,746 differentially expressed genes (DEGs) were identified in gills and heart, respectively. Expression changes of nine genes in each tissue were further validated by the qPCR. Based on KEGG and Gene ontology enrichments, we found that various innate immunity-related genes, such as complement components (C1qs, C2, C3, C6, and C7), chemokines (CCL3, CCL17, CCL19, CCL25, and CXCL8_L3), chemokine receptors (CCR9, CXCR1, and CXCR3), and nitric oxide synthase (NOS), were significantly down-regulated in gills and/or heart, suggesting that innate immune processes mediated by these genes may be inhibited by hypoxia. The genes involved in both glycolysis pathway (LDHA) and tricarboxylic acid cycle (IDH2 and OGDH) were up-regulated in gills and heart of hypoxic large yellow croakers, possibly because gill and heart tissues need enough energy to accelerate gas exchange and blood circulation. Hypoxia also affected the ion transport in gills of large yellow croaker, through down-regulating the expression levels of numerous classical ion transporters, including HVCN1, SLC20A2, SLC4A4, RHBG, RHCG, and SCN4A, suggesting an energy conservation strategy to hypoxia stress. All these results indicate that the immune processes, glycolytic pathways, and ion transport were significantly altered in gills and/or heart of large yellow croaker under hypoxia, possibly contributing to maintain cellular energy balance during hypoxia. Our data, therefore, afford new information to understand the tissue-specific molecular responses of bony fish to hypoxia stress.
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Affiliation(s)
- Yinnan Mu
- Key Laboratory of Marine Biotechnology of Fujian Province, Institute of Oceanology, Fujian Agriculture and Forestry University, Fuzhou, 350002, PR China
| | - Wanru Li
- Key Laboratory of Marine Biotechnology of Fujian Province, Institute of Oceanology, Fujian Agriculture and Forestry University, Fuzhou, 350002, PR China
| | - Zuyun Wei
- Key Laboratory of Marine Biotechnology of Fujian Province, Institute of Oceanology, Fujian Agriculture and Forestry University, Fuzhou, 350002, PR China
| | - Lianghua He
- Key Laboratory of Marine Biotechnology of Fujian Province, Institute of Oceanology, Fujian Agriculture and Forestry University, Fuzhou, 350002, PR China
| | - Weini Zhang
- Key Laboratory of Marine Biotechnology of Fujian Province, Institute of Oceanology, Fujian Agriculture and Forestry University, Fuzhou, 350002, PR China
| | - Xinhua Chen
- Key Laboratory of Marine Biotechnology of Fujian Province, Institute of Oceanology, Fujian Agriculture and Forestry University, Fuzhou, 350002, PR China; Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, 519000, PR China.
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30
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Farooque U, Cheema AY, Kumar R, Saini G, Kataria S. Primary Periodic Paralyses: A Review of Etiologies and Their Pathogeneses. Cureus 2020; 12:e10112. [PMID: 33005530 PMCID: PMC7523540 DOI: 10.7759/cureus.10112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Periodic paralyses are a group of disorders characterized by episodes of muscle paralyses. They are mainly divided as primary (hereditary) and secondary (acquired) periodic paralyses. Primary periodic paralyses occur as a result of mutations in genes encoding subunits of muscle membrane channel proteins such as sodium, calcium, and potassium channels, resulting in impairment of their properties. Primary periodic paralyses are further classified on the basis of affected ion channels and other associated complications. Some of these periodic paralyses are hyperkalemic periodic paralysis (Na-channel mutation), hypokalemic periodic paralysis (Na- or Ca-channel mutation), Andersen’s syndrome (K-channel mutation), etc.
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31
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Abstract
PURPOSE OF REVIEW This article aims to review the current and upcoming treatment options of primary muscle channelopathies including the non-dystrophic myotonias and periodic paralyses. RECENT FINDINGS The efficacy of mexiletine in the treatment of myotonia is now supported by two randomised placebo-controlled trials, one of which utilised a novel aggregated n-of-1 design. This has resulted in licencing of the drug via orphan drug status. There is also good evidence that mexiletine is well tolerated and safe in this patient group without the need for intensive monitoring. A range of alternative antimyotonic treatment options include lamotrigine, carbamazepine and ranolazine exist with variable evidence base. In vitro studies have shown insight into reasons for treatment failure of some medications with certain genotypes opening the era of mutation-specific therapy such as use of flecainide. In the periodic paralyses, the ability of MRI to distinguish between reversible oedema and irreversible fatty replacement makes it an increasingly useful tool to guide and assess pharmacological treatment. Unfortunately, the striking efficacy of bumetanide in hypokalaemic periodic paralysis animal models was not replicated in a recent pilot study in humans. SUMMARY The treatment of skeletal muscle channelopathies combines dietary and lifestyle advice together with pharmacological interventions. The rarity of these conditions remains a barrier for clinical studies but the example of the aggregated n-of-1 trial of mexiletine shows that innovative trial design can overcome these hurdles. Further research is required to test efficacy of drugs shown to have promising characteristics in preclinical experiments such as safinamide, riluzule and magnesium for myotonia or bumetanide for hypokalaemic periodic paralysis.
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Affiliation(s)
- Nantaporn Jitpimolmard
- Queen Square Centre for Neuromuscular Diseases, UCL Queen Square Institute of Neurology, UCL, London, UK
- Rehabilitation Medicine Department, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand
| | - Emma Matthews
- Queen Square Centre for Neuromuscular Diseases, UCL Queen Square Institute of Neurology, UCL, London, UK
- Atkinson-Morley Neuromuscular Centre, St George’s University Hospitals Foundation Trust, London, UK
| | - Doreen Fialho
- Queen Square Centre for Neuromuscular Diseases, UCL Queen Square Institute of Neurology, UCL, London, UK
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Echaniz-Laguna A, Biancalana V, Nadaj-Pakleza A, Fournier E, Matthews E, Hanna MG, Männikkö R. Homozygous C-terminal loss-of-function Na V1.4 variant in a patient with congenital myasthenic syndrome. J Neurol Neurosurg Psychiatry 2020; 91:898-900. [PMID: 32487525 PMCID: PMC7115925 DOI: 10.1136/jnnp-2020-323173] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 04/24/2020] [Accepted: 05/02/2020] [Indexed: 11/04/2022]
Affiliation(s)
- Andoni Echaniz-Laguna
- Department of Neurology, APHP, CHU de Bicêtre, Le Kremlin Bicêtre, 94276, France
- French National Reference Center for Rare Neuropathies (NNERF), Le Kremlin Bicêtre, 94276, France
- INSERM U1195 & Paris-Sud University, Le Kremlin Bicêtre, 94276, France
- Corresponding author: Roope MÄNNIKKÖ, PhD, MRC Centre for Neuromuscular Diseases, Department of Molecular Neuroscience, UCL Institute of Neurology, London, WC1N 3BG, UK. , T: +44 2034484208
| | - Valérie Biancalana
- Laboratoire Diagnostic Génétique, CHR, Strasbourg, France
- Institut de Génétique et de Biologie Moleculaire et Cellulaire (IGBMC), INSERM U964, CNRS UMR 7104, Federation de Medecine Translationnelle de Strasbourg, Universite de Strasbourg, Illkirch, France
| | | | - Emmanuel Fournier
- Department of Neurophysiology, APHP, CHU Pitié-Salpetriêrè, 75013 Paris, France
| | - Emma Matthews
- Department of Neuromuscular diseases, UCL Institute of Neurology, London, WC1N 3BG, UK
| | - Michael G. Hanna
- Department of Neuromuscular diseases, UCL Institute of Neurology, London, WC1N 3BG, UK
| | - Roope Männikkö
- Department of Neuromuscular diseases, UCL Institute of Neurology, London, WC1N 3BG, UK
- Corresponding author: Roope MÄNNIKKÖ, PhD, MRC Centre for Neuromuscular Diseases, Department of Molecular Neuroscience, UCL Institute of Neurology, London, WC1N 3BG, UK. , T: +44 2034484208
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Vivekanandam V, Männikkö R, Matthews E, Hanna MG. Improving genetic diagnostics of skeletal muscle channelopathies. Expert Rev Mol Diagn 2020; 20:725-736. [PMID: 32657178 DOI: 10.1080/14737159.2020.1782195] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
INTRODUCTION Skeletal muscle channelopathies are rare inherited conditions that cause significant morbidity and impact on quality of life. Some subsets have a mortality risk. Improved genetic methodology and understanding of phenotypes have improved diagnostic accuracy and yield. AREAS COVERED We discuss diagnostic advances since the advent of next-generation sequencing and the role of whole exome and genome sequencing. Advances in genotype-phenotype-functional correlations have improved understanding of inheritance and phenotypes. We outline new phenotypes, particularly in the pediatric setting and consider co-existing mutations that may act as genetic modifiers. We also discuss four newly identified genes associated with skeletal muscle channelopathies. EXPERT OPINION Next-generation sequencing using gene panels has improved diagnostic rates, identified new mutations, and discovered patients with co-existing pathogenic mutations ('double trouble'). This field has previously focussed on single genes, but we are now beginning to understand interactions between co-existing mutations, genetic modifiers, and their role in pathomechanisms. New genetic observations in pediatric presentations of channelopathies broadens our understanding of the conditions. Genetic and mechanistic advances have increased the potential to develop treatments.
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Affiliation(s)
- Vinojini Vivekanandam
- Queen Square Centre for Neuromuscular Diseases and Department of Neuromuscular Diseases, Queen Square Institute of Neurology, UCL and National Hospital for Neurology and Neurosurgery , London, UK
| | - Roope Männikkö
- Queen Square Centre for Neuromuscular Diseases and Department of Neuromuscular Diseases, Queen Square Institute of Neurology, UCL and National Hospital for Neurology and Neurosurgery , London, UK
| | - Emma Matthews
- Queen Square Centre for Neuromuscular Diseases and Department of Neuromuscular Diseases, Queen Square Institute of Neurology, UCL and National Hospital for Neurology and Neurosurgery , London, UK
| | - Michael G Hanna
- Queen Square Centre for Neuromuscular Diseases and Department of Neuromuscular Diseases, Queen Square Institute of Neurology, UCL and National Hospital for Neurology and Neurosurgery , London, UK
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Troha Gergeli A, Neubauer D, Golli T, Butenko T, Loboda T, Maver A, Osredkar D. Prevalence and genetic subtypes of congenital myasthenic syndromes in the pediatric population of Slovenia. Eur J Paediatr Neurol 2020; 26:34-38. [PMID: 32070632 DOI: 10.1016/j.ejpn.2020.02.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/03/2019] [Revised: 01/08/2020] [Accepted: 02/07/2020] [Indexed: 12/15/2022]
Abstract
AIM Congenital myasthenic syndromes (CMS) are rare, genetically and phenotypically diverse disorders of neuromuscular transmission. Data on prevalence among children are scarce. Whole exome sequencing facilitated discovery of novel CMS mutations and enabled targeted treatment. Our aim was to identify the prevalence, genetic subtypes and clinical characteristics of CMS in pediatric population of Slovenia. METHODS In this observational, national, cross-sectional study, medical records were retrospectively reviewed. Children with genetically confirmed CMS, referred over a 19 - year period (2000-2018) to the University Medical Centre, Ljubljana, Slovenia, were included in the study. Genetic and phenotypic characteristics were collected and prevalence of CMS in children was calculated. RESULTS Eight children with a confirmed genetic mutation in 5 different genes (CHRNE, CHRND, RAPSN, CHAT, MUSK) causative of the CMS were identified. Calculated prevalence of genetically confirmed CMS was 22.2 cases per 1.000.000 children at the end of 2018. INTERPRETATION The prevalence of genetically confirmed CMS in Slovenian children at the end of 2018 exceeds previously reported prevalence by more than two-fold, which suggests that prevalence in the literature is likely to be underestimated. Two extremely rarely detected mutations in MUSK and CHRND gene were detected and patient's clinical descriptions add important information on genotype-phenotype correlation.
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Affiliation(s)
- Anja Troha Gergeli
- Department of Child, Adolescent and Developmental Neurology, University Children's Hospital, University Medical Centre Ljubljana, Slovenia
| | - David Neubauer
- Department of Child, Adolescent and Developmental Neurology, University Children's Hospital, University Medical Centre Ljubljana, Slovenia; Faculty of Medicine, University of Ljubljana, Slovenia
| | - Tanja Golli
- Department of Child, Adolescent and Developmental Neurology, University Children's Hospital, University Medical Centre Ljubljana, Slovenia; Faculty of Medicine, University of Ljubljana, Slovenia
| | - Tita Butenko
- Department of Child, Adolescent and Developmental Neurology, University Children's Hospital, University Medical Centre Ljubljana, Slovenia
| | - Tanja Loboda
- Department of Child, Adolescent and Developmental Neurology, University Children's Hospital, University Medical Centre Ljubljana, Slovenia
| | - Aleš Maver
- Clinical Institute of Medical Genetics, University Medical Centre Ljubljana, Slovenia
| | - Damjan Osredkar
- Department of Child, Adolescent and Developmental Neurology, University Children's Hospital, University Medical Centre Ljubljana, Slovenia; Faculty of Medicine, University of Ljubljana, Slovenia.
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Malak OA, Abderemane-Ali F, Wei Y, Coyan FC, Pontus G, Shaya D, Marionneau C, Loussouarn G. Up-regulation of voltage-gated sodium channels by peptides mimicking S4-S5 linkers reveals a variation of the ligand-receptor mechanism. Sci Rep 2020; 10:5852. [PMID: 32246066 PMCID: PMC7125111 DOI: 10.1038/s41598-020-62615-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Accepted: 03/12/2020] [Indexed: 11/09/2022] Open
Abstract
Prokaryotic NaV channels are tetramers and eukaryotic NaV channels consist of a single subunit containing four domains. Each monomer/domain contains six transmembrane segments (S1-S6), S1-S4 being the voltage-sensor domain and S5-S6 the pore domain. A crystal structure of NaVMs, a prokaryotic NaV channel, suggests that the S4-S5 linker (S4-S5L) interacts with the C-terminus of S6 (S6T) to stabilize the gate in the open state. However, in several voltage-gated potassium channels, using specific S4-S5L-mimicking peptides, we previously demonstrated that S4-S5L/S6T interaction stabilizes the gate in the closed state. Here, we used the same strategy on another prokaryotic NaV channel, NaVSp1, to test whether equivalent peptides stabilize the channel in the open or closed state. A NaVSp1-specific S4-S5L peptide, containing the residues supposed to interact with S6T according to the NaVMs structure, induced both an increase in NaVSp1 current density and a negative shift in the activation curve, consistent with S4-S5L stabilizing the open state. Using this approach on a human NaV channel, hNaV1.4, and testing 12 hNaV1.4 S4-S5L peptides, we identified four activating S4-S5L peptides. These results suggest that, in eukaryotic NaV channels, the S4-S5L of DI, DII and DIII domains allosterically modulate the activation gate and stabilize its open state.
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Affiliation(s)
- Olfat A Malak
- Université de Nantes, CNRS, INSERM, l'institut du thorax, F-44000, Nantes, France.,Buck Institute for Research on Aging, 8001 Redwood Blvd, Novato, California, 94945, USA
| | - Fayal Abderemane-Ali
- Université de Nantes, CNRS, INSERM, l'institut du thorax, F-44000, Nantes, France.,Cardiovascular Research Institute, University of California, San Francisco, California, 941158-9001, USA
| | - Yue Wei
- Université de Nantes, CNRS, INSERM, l'institut du thorax, F-44000, Nantes, France.,Department of Cardiology, Shanghai Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Fabien C Coyan
- Université de Nantes, CNRS, INSERM, l'institut du thorax, F-44000, Nantes, France
| | - Gilyane Pontus
- Université de Nantes, CNRS, INSERM, l'institut du thorax, F-44000, Nantes, France
| | - David Shaya
- Cardiovascular Research Institute, University of California, San Francisco, California, 941158-9001, USA
| | - Céline Marionneau
- Université de Nantes, CNRS, INSERM, l'institut du thorax, F-44000, Nantes, France
| | - Gildas Loussouarn
- Université de Nantes, CNRS, INSERM, l'institut du thorax, F-44000, Nantes, France.
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Matthews E, Balestrini S, Sisodiya SM, Hanna MG. Muscle and brain sodium channelopathies: genetic causes, clinical phenotypes, and management approaches. THE LANCET CHILD & ADOLESCENT HEALTH 2020; 4:536-547. [PMID: 32142633 DOI: 10.1016/s2352-4642(19)30425-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Revised: 10/29/2019] [Accepted: 12/12/2019] [Indexed: 01/26/2023]
Abstract
Voltage-gated sodium channels are essential for excitability of skeletal muscle fibres and neurons. An increasing number of disabling or fatal paediatric neurological disorders linked to mutations of voltage-gated sodium channel genes are recognised. Muscle phenotypes include episodic paralysis, myotonia, neonatal hypotonia, respiratory compromise, laryngospasm or stridor, congenital myasthenia, and myopathy. Evidence suggests a possible link between sodium channel dysfunction and sudden infant death. Increasingly recognised phenotypes of brain sodium channelopathies include several epilepsy disorders and complex encephalopathies. Together, these early-onset muscle and brain phenotypes have a substantial morbidity and a considerable mortality. Important advances in understanding the pathophysiological mechanisms underlying these channelopathies have helped to identify effective targeted therapies. The availability of effective treatments underlines the importance of increasing clinical awareness and the need to achieve a precise genetic diagnosis. In this Review, we describe the expanded range of phenotypes of muscle and brain sodium channelopathies and the underlying knowledge regarding mechanisms of sodium channel dysfunction. We also outline a diagnostic approach and review the available treatment options.
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Affiliation(s)
- Emma Matthews
- Department of Neuromuscular Diseases, Medical Research Council Centre for Neuromuscular Diseases, University College London Queen Square Institute of Neurology, London, UK; National Hospital for Neurology and Neurosurgery, University College London Hospitals National Health Service Foundation Trust, London, UK.
| | - Simona Balestrini
- Department of Clinical and Experimental Epilepsy, University College London Queen Square Institute of Neurology, London, UK; Chalfont Centre for Epilepsy, Buckinghamshire, UK; National Hospital for Neurology and Neurosurgery, University College London Hospitals National Health Service Foundation Trust, London, UK
| | - Sanjay M Sisodiya
- Department of Clinical and Experimental Epilepsy, University College London Queen Square Institute of Neurology, London, UK; Chalfont Centre for Epilepsy, Buckinghamshire, UK; National Hospital for Neurology and Neurosurgery, University College London Hospitals National Health Service Foundation Trust, London, UK
| | - Michael G Hanna
- Department of Neuromuscular Diseases, Medical Research Council Centre for Neuromuscular Diseases, University College London Queen Square Institute of Neurology, London, UK; National Hospital for Neurology and Neurosurgery, University College London Hospitals National Health Service Foundation Trust, London, UK
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Elia N, Nault T, McMillan HJ, Graham GE, Huang L, Cannon SC. Myotonic Myopathy With Secondary Joint and Skeletal Anomalies From the c.2386C>G, p.L769V Mutation in SCN4A. Front Neurol 2020; 11:77. [PMID: 32117035 PMCID: PMC7031655 DOI: 10.3389/fneur.2020.00077] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Accepted: 01/22/2020] [Indexed: 11/22/2022] Open
Abstract
The phenotypic spectrum associated with the skeletal muscle voltage-gated sodium channel gene (SCN4A) has expanded with advancements in genetic testing. Autosomal dominant SCN4A mutations were first linked to hyperkalemic periodic paralysis, then subsequently included paramyotonia congenita, several variants of myotonia, and finally hypokalemic periodic paralysis. Biallelic recessive mutations were later identified in myasthenic myopathy and in infants showing a severe congenital myopathy with hypotonia. We report a patient with a pathogenic de novo SCN4A variant, c.2386C>G p.L769V at a highly conserved leucine. The phenotype was manifest at birth with arthrogryposis multiplex congenita, severe episodes of bronchospasm that responded immediately to carbamazepine therapy, and electromyographic evidence of widespread myotonia. Another de novo case of p.L769V has been reported with hip dysplasia, scoliosis, myopathy, and later paramyotonia. Expression studies of L796V mutant channels showed predominantly gain-of-function changes, that included defects of slow inactivation. Computer simulations of muscle excitability reveal a strong predisposition to myotonia with exceptionally prolonged bursts of discharges, when the L796V defects are included. We propose L769V is a pathogenic variant, that along with other cases in the literature, defines a new dominant SCN4A disorder of myotonic myopathy with secondary congenital joint and skeletal involvement.
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Affiliation(s)
- Nathaniel Elia
- Department of Physiology, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States
- Molecular, Cellular, and Integrative Physiology Program, UCLA, Los Angeles, CA, United States
| | - Trystan Nault
- Division of Neurology, Children's Hospital of Eastern Ontario, University of Ottawa, Ottawa, ON, Canada
| | - Hugh J. McMillan
- Division of Neurology, Children's Hospital of Eastern Ontario, University of Ottawa, Ottawa, ON, Canada
| | - Gail E. Graham
- Department of Genetics, Children's Hospital of Eastern Ontario, University of Ottawa, Ottawa, ON, Canada
| | - Lijia Huang
- Department of Genetics, Children's Hospital of Eastern Ontario, University of Ottawa, Ottawa, ON, Canada
| | - Stephen C. Cannon
- Department of Physiology, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States
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Mukund K, Subramaniam S. Skeletal muscle: A review of molecular structure and function, in health and disease. WILEY INTERDISCIPLINARY REVIEWS. SYSTEMS BIOLOGY AND MEDICINE 2020; 12:e1462. [PMID: 31407867 PMCID: PMC6916202 DOI: 10.1002/wsbm.1462] [Citation(s) in RCA: 283] [Impact Index Per Article: 56.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Revised: 07/03/2019] [Accepted: 07/03/2019] [Indexed: 12/11/2022]
Abstract
Decades of research in skeletal muscle physiology have provided multiscale insights into the structural and functional complexity of this important anatomical tissue, designed to accomplish the task of generating contraction, force and movement. Skeletal muscle can be viewed as a biomechanical device with various interacting components including the autonomic nerves for impulse transmission, vasculature for efficient oxygenation, and embedded regulatory and metabolic machinery for maintaining cellular homeostasis. The "omics" revolution has propelled a new era in muscle research, allowing us to discern minute details of molecular cross-talk required for effective coordination between the myriad interacting components for efficient muscle function. The objective of this review is to provide a systems-level, comprehensive mapping the molecular mechanisms underlying skeletal muscle structure and function, in health and disease. We begin this review with a focus on molecular mechanisms underlying muscle tissue development (myogenesis), with an emphasis on satellite cells and muscle regeneration. We next review the molecular structure and mechanisms underlying the many structural components of the muscle: neuromuscular junction, sarcomere, cytoskeleton, extracellular matrix, and vasculature surrounding muscle. We highlight aberrant molecular mechanisms and their possible clinical or pathophysiological relevance. We particularly emphasize the impact of environmental stressors (inflammation and oxidative stress) in contributing to muscle pathophysiology including atrophy, hypertrophy, and fibrosis. This article is categorized under: Physiology > Mammalian Physiology in Health and Disease Developmental Biology > Developmental Processes in Health and Disease Models of Systems Properties and Processes > Cellular Models.
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Affiliation(s)
- Kavitha Mukund
- Department of BioengineeringUniversity of CaliforniaSan DiegoCalifornia
| | - Shankar Subramaniam
- Department of Bioengineering, Bioinformatics & Systems BiologyUniversity of CaliforniaSan DiegoCalifornia
- Department of Computer Science and EngineeringUniversity of CaliforniaSan DiegoCalifornia
- Department of Cellular and Molecular Medicine and NanoengineeringUniversity of CaliforniaSan DiegoCalifornia
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Metzger S, Dupont C, Voss AA, Rich MM. Central Role of Subthreshold Currents in Myotonia. Ann Neurol 2019; 87:175-183. [PMID: 31725924 DOI: 10.1002/ana.25646] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Revised: 11/12/2019] [Accepted: 11/12/2019] [Indexed: 01/11/2023]
Abstract
It is generally thought that muscle excitability is almost exclusively controlled by currents responsible for generation of action potentials. We propose that smaller ion channel currents that contribute to setting the resting potential and to subthreshold fluctuations in membrane potential can also modulate excitability in important ways. These channels open at voltages more negative than the action potential threshold and are thus termed subthreshold currents. As subthreshold currents are orders of magnitude smaller than the currents responsible for the action potential, they are hard to identify and easily overlooked. Discovery of their importance in regulation of excitability opens new avenues for improved therapy for muscle channelopathies and diseases of the neuromuscular junction. ANN NEUROL 2020;87:175-183.
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Affiliation(s)
- Sabrina Metzger
- Department of Neuroscience, Cell Biology, and Physiology, Wright State University, Dayton, OH
| | - Chris Dupont
- Department of Neuroscience, Cell Biology, and Physiology, Wright State University, Dayton, OH
| | - Andrew A Voss
- Department of Biology, Wright State University, Dayton, OH
| | - Mark M Rich
- Department of Neuroscience, Cell Biology, and Physiology, Wright State University, Dayton, OH
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40
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Pechmann A, Eckenweiler M, Schorling D, Stavropoulou D, Lochmüller H, Kirschner J. De novo variant in SCN4A causes neonatal sodium channel myotonia with general muscle stiffness and respiratory failure. Neuromuscul Disord 2019; 29:907-909. [PMID: 31732390 DOI: 10.1016/j.nmd.2019.09.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Revised: 06/16/2019] [Accepted: 09/02/2019] [Indexed: 11/24/2022]
Abstract
Variants of the skeletal muscle sodium channel gene SCN4A are associated with different neuromuscular disorders including sodium channel myotonia. Here, we report an infant with a de novo variant in SCN4A presenting with neonatal onset of severe muscle stiffness with involvement of facial and eyelid muscles, and life-threatening events with respiratory failure due to severe apnoea and thorax rigidity. The boy dramatically improved in both respiratory and motor function under carbamazepine therapy.
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Affiliation(s)
- Astrid Pechmann
- Department of Neuropediatrics and Muscle Disorders, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Germany
| | - Matthias Eckenweiler
- Department of Neuropediatrics and Muscle Disorders, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Germany
| | - David Schorling
- Department of Neuropediatrics and Muscle Disorders, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Germany
| | - Dimitra Stavropoulou
- Department of General Pediatrics, Divisions of Neonatology/Intensive Care Medicine, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Germany
| | - Hanns Lochmüller
- Department of Neuropediatrics and Muscle Disorders, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Germany; Children's Hospital of Eastern Ontario Research Institute; Division of Neurology, Department of Medicine, The Ottawa Hospital; and Brain and Mind Research Institute, University of Ottawa, Ottawa, Canada
| | - Janbernd Kirschner
- Department of Neuropediatrics and Muscle Disorders, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Germany; Department of Neuropediatrics, University Hospital Bonn, University of Bonn, Bonn, Germany.
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41
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Waldrop M, Amornvit J, Pierson CR, Boue DR, Sahenk Z. A Novel De Novo Heterozygous SCN4a Mutation Causing Congenital Myopathy, Myotonia and Multiple Congenital Anomalies. J Neuromuscul Dis 2019; 6:467-473. [DOI: 10.3233/jnd-190425] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
- Megan Waldrop
- Center for Gene Therapy, The Research Institute at Nationwide Children’s Hospital, Columbus, OH, USA
- Departments of Pediatrics and Neurology, Nationwide Children’s Hospital/The Ohio State University, Columbus, OH, USA
| | - Jakkrit Amornvit
- Center for Gene Therapy, The Research Institute at Nationwide Children’s Hospital, Columbus, OH, USA
- King Chulalongkorn Memorial Hospital and Department of Medicine, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
| | - Christopher R. Pierson
- Department of Pathology and Laboratory Medicine, Nationwide Children’s Hospital, Columbus, OH, USA
- Division of Anatomy, The Ohio State University, Columbus, OH, USA
- The Department of Pathology, The Ohio State University, Columbus, OH, USA
| | - Daniel R. Boue
- Department of Pathology and Laboratory Medicine, Nationwide Children’s Hospital, Columbus, OH, USA
- The Department of Pathology, The Ohio State University, Columbus, OH, USA
| | - Zarife Sahenk
- Center for Gene Therapy, The Research Institute at Nationwide Children’s Hospital, Columbus, OH, USA
- Departments of Pediatrics and Neurology, Nationwide Children’s Hospital/The Ohio State University, Columbus, OH, USA
- Department of Pathology and Laboratory Medicine, Nationwide Children’s Hospital, Columbus, OH, USA
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Nicolau S, Kao JC, Liewluck T. Trouble at the junction: When myopathy and myasthenia overlap. Muscle Nerve 2019; 60:648-657. [PMID: 31449669 DOI: 10.1002/mus.26676] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Revised: 08/18/2019] [Accepted: 08/20/2019] [Indexed: 12/22/2022]
Abstract
Although myopathies and neuromuscular junction disorders are typically distinct, their coexistence has been reported in several inherited and acquired conditions. Affected individuals have variable clinical phenotypes but typically display both a decrement on repetitive nerve stimulation and myopathic findings on muscle biopsy. Inherited causes include myopathies related to mutations in BIN1, DES, DNM2, GMPPB, MTM1, or PLEC and congenital myasthenic syndromes due to mutations in ALG2, ALG14, COL13A1, DOK7, DPAGT1, or GFPT1. Additionally, a decrement due to muscle fiber inexcitability is observed in certain myotonic disorders. The identification of a defect of neuromuscular transmission in an inherited myopathy may assist in establishing a molecular diagnosis and in selecting patients who would benefit from pharmacological correction of this defect. Acquired cases meanwhile stem from the co-occurrence of myasthenia gravis or Lambert-Eaton myasthenic syndrome with an immune-mediated myopathy, which may be due to paraneoplastic disorders or exposure to immune checkpoint inhibitors.
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Affiliation(s)
- Stefan Nicolau
- Department of Neurology, Mayo Clinic, Rochester, Minnesota
| | - Justin C Kao
- Department of Neurology, Auckland City Hospital, Auckland, New Zealand
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43
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Türkdoğan D, Matthews E, Usluer S, Gündoğdu A, Uluç K, Mannikko R, Hanna MG, Sisodiya SM, Çağlayan HS. Possible role of SCN4A skeletal muscle mutation in apnea during seizure. Epilepsia Open 2019; 4:498-503. [PMID: 31440732 PMCID: PMC6698682 DOI: 10.1002/epi4.12347] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Revised: 05/20/2019] [Accepted: 06/08/2019] [Indexed: 01/05/2023] Open
Abstract
SCN4A gene mutations cause a number of neuromuscular phenotypes including myotonia. A subset of infants with myotonia-causing mutations experience severe life-threatening episodic laryngospasm with apnea. We have recently identified similar SCN4A mutations in association with sudden infant death syndrome. Laryngospasm has also been proposed as a contributory mechanism to some cases of sudden unexpected death in epilepsy (SUDEP). We report an infant with EEG-confirmed seizures and recurrent apneas. Whole-exome sequencing identified a known pathogenic mutation in the SCN4A gene that has been reported in several unrelated families with myotonic disorder. We propose that the SCN4A mutation contributed to the apneas in our case, irrespective of the underlying cause of the epilepsy. We suggest this supports the notion that laryngospasm may contribute to some cases of SUDEP, and implicates a possible shared mechanism between a proportion of sudden infant deaths and sudden unexpected deaths in epilepsy.
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Affiliation(s)
- Dilşad Türkdoğan
- Medical Faculty, Department of Child NeurologyMarmara UniversityIstanbulTurkey
| | - Emma Matthews
- Queen Square Centre for Neuromuscular Diseases, UCL Queen Square Institute of NeurologyUCL and National Hospital for Neurology and NeurosurgeryLondonUK
| | - Sunay Usluer
- Formerly Affiliated with Department of Molecular Biology and GeneticsBoğaziçi UniversityIstanbulTurkey
| | - Aslı Gündoğdu
- Department of Molecular Biology and GeneticsBoğaziçi UniversityIstanbulTurkey
| | - Kayıhan Uluç
- Medical Faculty, Department of Clinical Neurophysiology and NeurologyMarmara UniversityIstanbulTurkey
| | - Roope Mannikko
- Queen Square Centre for Neuromuscular Diseases, UCL Queen Square Institute of NeurologyUCL and National Hospital for Neurology and NeurosurgeryLondonUK
| | - Michael G. Hanna
- Queen Square Centre for Neuromuscular Diseases, UCL Queen Square Institute of NeurologyUCL and National Hospital for Neurology and NeurosurgeryLondonUK
| | - Sanjay M. Sisodiya
- Department of Clinical and Experimental EpilepsyUCL Queen Square Institute of NeurologyLondonUK
- Chalfont Centre for EpilepsyBucksUK
| | - Hande S. Çağlayan
- Department of Molecular Biology and GeneticsBoğaziçi UniversityIstanbulTurkey
- İzmir Biomedicine and Genome CenterİzmirTurkey
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Elia N, Palmio J, Castañeda MS, Shieh PB, Quinonez M, Suominen T, Hanna MG, Männikkö R, Udd B, Cannon SC. Myasthenic congenital myopathy from recessive mutations at a single residue in Na V1.4. Neurology 2019; 92:e1405-e1415. [PMID: 30824560 PMCID: PMC6453767 DOI: 10.1212/wnl.0000000000007185] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Accepted: 11/04/2018] [Indexed: 01/12/2023] Open
Abstract
OBJECTIVE To identify the genetic and physiologic basis for recessive myasthenic congenital myopathy in 2 families, suggestive of a channelopathy involving the sodium channel gene, SCN4A. METHODS A combination of whole exome sequencing and targeted mutation analysis, followed by voltage-clamp studies of mutant sodium channels expressed in fibroblasts (HEK cells) and Xenopus oocytes. RESULTS Missense mutations of the same residue in the skeletal muscle sodium channel, R1460 of NaV1.4, were identified in a family and a single patient of Finnish origin (p.R1460Q) and a proband in the United States (p.R1460W). Congenital hypotonia, breathing difficulties, bulbar weakness, and fatigability had recessive inheritance (homozygous p.R1460W or compound heterozygous p.R1460Q and p.R1059X), whereas carriers were either asymptomatic (p.R1460W) or had myotonia (p.R1460Q). Sodium currents conducted by mutant channels showed unusual mixed defects with both loss-of-function (reduced amplitude, hyperpolarized shift of inactivation) and gain-of-function (slower entry and faster recovery from inactivation) changes. CONCLUSIONS Novel mutations in families with myasthenic congenital myopathy have been identified at p.R1460 of the sodium channel. Recessive inheritance, with experimentally established loss-of-function, is a consistent feature of sodium channel based myasthenia, whereas the mixed gain of function for p.R1460 may also cause susceptibility to myotonia.
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Affiliation(s)
- Nathaniel Elia
- From the Departments of Physiology (N.E., M.Q., S.C.C.) and Neurology (P.B.S.), David Geffen School of Medicine at UCLA; Molecular and Cellular Integrative Physiology Program at UCLA (N.E., S.C.C.), Los Angeles, CA; Tampere Neuromuscular Center (J.P., T.S., B.U.), Tampere University and University Hospital, Finland; MRC Centre for Neuromuscular Diseases (M.S.C., M.G.H., R.M.), Department of Neuromuscular Disease, UCL Institute of Neurology, London, UK; Folkhälsan Genetic Institute (B.U.), Helsinki; and Neurology Department (B.U.), Vasa Central Hospital, Finland
| | - Johanna Palmio
- From the Departments of Physiology (N.E., M.Q., S.C.C.) and Neurology (P.B.S.), David Geffen School of Medicine at UCLA; Molecular and Cellular Integrative Physiology Program at UCLA (N.E., S.C.C.), Los Angeles, CA; Tampere Neuromuscular Center (J.P., T.S., B.U.), Tampere University and University Hospital, Finland; MRC Centre for Neuromuscular Diseases (M.S.C., M.G.H., R.M.), Department of Neuromuscular Disease, UCL Institute of Neurology, London, UK; Folkhälsan Genetic Institute (B.U.), Helsinki; and Neurology Department (B.U.), Vasa Central Hospital, Finland
| | - Marisol Sampedro Castañeda
- From the Departments of Physiology (N.E., M.Q., S.C.C.) and Neurology (P.B.S.), David Geffen School of Medicine at UCLA; Molecular and Cellular Integrative Physiology Program at UCLA (N.E., S.C.C.), Los Angeles, CA; Tampere Neuromuscular Center (J.P., T.S., B.U.), Tampere University and University Hospital, Finland; MRC Centre for Neuromuscular Diseases (M.S.C., M.G.H., R.M.), Department of Neuromuscular Disease, UCL Institute of Neurology, London, UK; Folkhälsan Genetic Institute (B.U.), Helsinki; and Neurology Department (B.U.), Vasa Central Hospital, Finland
| | - Perry B Shieh
- From the Departments of Physiology (N.E., M.Q., S.C.C.) and Neurology (P.B.S.), David Geffen School of Medicine at UCLA; Molecular and Cellular Integrative Physiology Program at UCLA (N.E., S.C.C.), Los Angeles, CA; Tampere Neuromuscular Center (J.P., T.S., B.U.), Tampere University and University Hospital, Finland; MRC Centre for Neuromuscular Diseases (M.S.C., M.G.H., R.M.), Department of Neuromuscular Disease, UCL Institute of Neurology, London, UK; Folkhälsan Genetic Institute (B.U.), Helsinki; and Neurology Department (B.U.), Vasa Central Hospital, Finland
| | - Marbella Quinonez
- From the Departments of Physiology (N.E., M.Q., S.C.C.) and Neurology (P.B.S.), David Geffen School of Medicine at UCLA; Molecular and Cellular Integrative Physiology Program at UCLA (N.E., S.C.C.), Los Angeles, CA; Tampere Neuromuscular Center (J.P., T.S., B.U.), Tampere University and University Hospital, Finland; MRC Centre for Neuromuscular Diseases (M.S.C., M.G.H., R.M.), Department of Neuromuscular Disease, UCL Institute of Neurology, London, UK; Folkhälsan Genetic Institute (B.U.), Helsinki; and Neurology Department (B.U.), Vasa Central Hospital, Finland
| | - Tiina Suominen
- From the Departments of Physiology (N.E., M.Q., S.C.C.) and Neurology (P.B.S.), David Geffen School of Medicine at UCLA; Molecular and Cellular Integrative Physiology Program at UCLA (N.E., S.C.C.), Los Angeles, CA; Tampere Neuromuscular Center (J.P., T.S., B.U.), Tampere University and University Hospital, Finland; MRC Centre for Neuromuscular Diseases (M.S.C., M.G.H., R.M.), Department of Neuromuscular Disease, UCL Institute of Neurology, London, UK; Folkhälsan Genetic Institute (B.U.), Helsinki; and Neurology Department (B.U.), Vasa Central Hospital, Finland
| | - Michael G Hanna
- From the Departments of Physiology (N.E., M.Q., S.C.C.) and Neurology (P.B.S.), David Geffen School of Medicine at UCLA; Molecular and Cellular Integrative Physiology Program at UCLA (N.E., S.C.C.), Los Angeles, CA; Tampere Neuromuscular Center (J.P., T.S., B.U.), Tampere University and University Hospital, Finland; MRC Centre for Neuromuscular Diseases (M.S.C., M.G.H., R.M.), Department of Neuromuscular Disease, UCL Institute of Neurology, London, UK; Folkhälsan Genetic Institute (B.U.), Helsinki; and Neurology Department (B.U.), Vasa Central Hospital, Finland
| | - Roope Männikkö
- From the Departments of Physiology (N.E., M.Q., S.C.C.) and Neurology (P.B.S.), David Geffen School of Medicine at UCLA; Molecular and Cellular Integrative Physiology Program at UCLA (N.E., S.C.C.), Los Angeles, CA; Tampere Neuromuscular Center (J.P., T.S., B.U.), Tampere University and University Hospital, Finland; MRC Centre for Neuromuscular Diseases (M.S.C., M.G.H., R.M.), Department of Neuromuscular Disease, UCL Institute of Neurology, London, UK; Folkhälsan Genetic Institute (B.U.), Helsinki; and Neurology Department (B.U.), Vasa Central Hospital, Finland
| | - Bjarne Udd
- From the Departments of Physiology (N.E., M.Q., S.C.C.) and Neurology (P.B.S.), David Geffen School of Medicine at UCLA; Molecular and Cellular Integrative Physiology Program at UCLA (N.E., S.C.C.), Los Angeles, CA; Tampere Neuromuscular Center (J.P., T.S., B.U.), Tampere University and University Hospital, Finland; MRC Centre for Neuromuscular Diseases (M.S.C., M.G.H., R.M.), Department of Neuromuscular Disease, UCL Institute of Neurology, London, UK; Folkhälsan Genetic Institute (B.U.), Helsinki; and Neurology Department (B.U.), Vasa Central Hospital, Finland
| | - Stephen C Cannon
- From the Departments of Physiology (N.E., M.Q., S.C.C.) and Neurology (P.B.S.), David Geffen School of Medicine at UCLA; Molecular and Cellular Integrative Physiology Program at UCLA (N.E., S.C.C.), Los Angeles, CA; Tampere Neuromuscular Center (J.P., T.S., B.U.), Tampere University and University Hospital, Finland; MRC Centre for Neuromuscular Diseases (M.S.C., M.G.H., R.M.), Department of Neuromuscular Disease, UCL Institute of Neurology, London, UK; Folkhälsan Genetic Institute (B.U.), Helsinki; and Neurology Department (B.U.), Vasa Central Hospital, Finland.
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Abstract
OBJECTIVES Congenital myasthenic syndromes (CMSs) are a genotypically and phenotypically heterogeneous group of neuromuscular disorders, which have in common an impaired neuromuscular transmission. Since the field of CMSs is steadily expanding, the present review aimed at summarizing and discussing current knowledge and recent advances concerning the etiology, clinical presentation, diagnosis, and treatment of CMSs. METHODS Systematic literature review. RESULTS Currently, mutations in 32 genes are made responsible for autosomal dominant or autosomal recessive CMSs. These mutations concern 8 presynaptic, 4 synaptic, 15 post-synaptic, and 5 glycosilation proteins. These proteins function as ion-channels, enzymes, or structural, signalling, sensor, or transporter proteins. The most common causative genes are CHAT, COLQ, RAPSN, CHRNE, DOK7, and GFPT1. Phenotypically, these mutations manifest as abnormal fatigability or permanent or fluctuating weakness of extra-ocular, facial, bulbar, axial, respiratory, or limb muscles, hypotonia, or developmental delay. Cognitive disability, dysmorphism, neuropathy, or epilepsy are rare. Low- or high-frequency repetitive nerve stimulation may show an abnormal increment or decrement, and SF-EMG an increased jitter or blockings. Most CMSs respond favourably to acetylcholine-esterase inhibitors, 3,4-diamino-pyridine, salbutamol, albuterol, ephedrine, fluoxetine, or atracurium. CONCLUSIONS CMSs are an increasingly recognised group of genetically transmitted defects, which usually respond favorably to drugs enhancing the neuromuscular transmission. CMSs need to be differentiated from neuromuscular disorders due to muscle or nerve dysfunction.
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Affiliation(s)
- Josef Finsterer
- Krankenanstalt Rudolfstiftung, Messerli Institute, Veterinary University of Vienna, Postfach 20, 1180, Vienna, Austria.
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46
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Targeted therapies for congenital myasthenic syndromes: systematic review and steps towards a treatabolome. Emerg Top Life Sci 2019; 3:19-37. [PMID: 30931400 PMCID: PMC6436731 DOI: 10.1042/etls20180100] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Despite recent scientific advances, most rare genetic diseases — including most neuromuscular diseases — do not currently have curative gene-based therapies available. However, in some cases, such as vitamin, cofactor or enzyme deficiencies, channelopathies and disorders of the neuromuscular junction, a confirmed genetic diagnosis provides guidance on treatment, with drugs available that may significantly alter the disease course, improve functional ability and extend life expectancy. Nevertheless, many treatable patients remain undiagnosed or do not receive treatment even after genetic diagnosis. The growth of computer-aided genetic analysis systems that enable clinicians to diagnose their undiagnosed patients has not yet been matched by genetics-based decision-support systems for treatment guidance. Generating a ‘treatabolome’ of treatable variants and the evidence for the treatment has the potential to increase treatment rates for treatable conditions. Here, we use the congenital myasthenic syndromes (CMS), a group of clinically and genetically heterogeneous but frequently treatable neuromuscular conditions, to illustrate the steps in the creation of a treatabolome for rare inherited diseases. We perform a systematic review of the evidence for pharmacological treatment of each CMS type, gathering evidence from 207 studies of over 1000 patients and stratifying by genetic defect, as treatment varies depending on the underlying cause. We assess the strength and quality of the evidence and create a dataset that provides the foundation for a computer-aided system to enable clinicians to gain easier access to information about treatable variants and the evidence they need to consider.
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47
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Italian recommendations for diagnosis and management of congenital myasthenic syndromes. Neurol Sci 2018; 40:457-468. [PMID: 30554356 DOI: 10.1007/s10072-018-3682-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Accepted: 12/10/2018] [Indexed: 12/11/2022]
Abstract
Congenital myasthenic syndromes (CMS) are genetic disorders due to mutations in genes encoding proteins involved in the neuromuscular junction structure and function. CMS usually present in young children, but perinatal and adult onset has been reported. Clinical presentation is highly heterogeneous, ranging from mild symptoms to severe manifestations, sometimes with life-threatening respiratory episodes, especially in the first decade of life. Although considered rare, CMS are probably underestimated due to diagnostic difficulties. Because of the several therapeutic opportunities, CMS should be always considered in the differential diagnosis of neuromuscular disorders. The Italian Network on CMS proposes here recommendations for proper CMS diagnosis and management, aiming to guide clinicians in their practical approach to CMS patients.
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48
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Sloth CK, Denti F, Schmitt N, Bentzen BH, Fagerberg C, Vissing J, Gaist D. Homozygosity for SCN4A Arg1142Gln causes congenital myopathy with variable disease expression. NEUROLOGY-GENETICS 2018; 4:e267. [PMID: 30283817 PMCID: PMC6167177 DOI: 10.1212/nxg.0000000000000267] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Accepted: 07/26/2018] [Indexed: 11/20/2022]
Affiliation(s)
- Christine K Sloth
- Department of Neurology (C.K.S., D.G.), Odense University Hospital; and Department of Clinical Research (C.K.S., D.G.), Faculty of Health Sciences, University of Southern Denmark, Odense; Department of Biomedical Sciences (F.D., N.S., B.H.B.), Faculty of Health and Medical Sciences, University of Copenhagen; Department of Clinical Genetics (C.F.), Odense University Hospital; and Copenhagen Neuromuscular Center, Department of Neurology (J.V.), Rigshospitalet, University of Copenhagen, Denmark
| | - Federico Denti
- Department of Neurology (C.K.S., D.G.), Odense University Hospital; and Department of Clinical Research (C.K.S., D.G.), Faculty of Health Sciences, University of Southern Denmark, Odense; Department of Biomedical Sciences (F.D., N.S., B.H.B.), Faculty of Health and Medical Sciences, University of Copenhagen; Department of Clinical Genetics (C.F.), Odense University Hospital; and Copenhagen Neuromuscular Center, Department of Neurology (J.V.), Rigshospitalet, University of Copenhagen, Denmark
| | - Nicole Schmitt
- Department of Neurology (C.K.S., D.G.), Odense University Hospital; and Department of Clinical Research (C.K.S., D.G.), Faculty of Health Sciences, University of Southern Denmark, Odense; Department of Biomedical Sciences (F.D., N.S., B.H.B.), Faculty of Health and Medical Sciences, University of Copenhagen; Department of Clinical Genetics (C.F.), Odense University Hospital; and Copenhagen Neuromuscular Center, Department of Neurology (J.V.), Rigshospitalet, University of Copenhagen, Denmark
| | - Bo Hjorth Bentzen
- Department of Neurology (C.K.S., D.G.), Odense University Hospital; and Department of Clinical Research (C.K.S., D.G.), Faculty of Health Sciences, University of Southern Denmark, Odense; Department of Biomedical Sciences (F.D., N.S., B.H.B.), Faculty of Health and Medical Sciences, University of Copenhagen; Department of Clinical Genetics (C.F.), Odense University Hospital; and Copenhagen Neuromuscular Center, Department of Neurology (J.V.), Rigshospitalet, University of Copenhagen, Denmark
| | - Christina Fagerberg
- Department of Neurology (C.K.S., D.G.), Odense University Hospital; and Department of Clinical Research (C.K.S., D.G.), Faculty of Health Sciences, University of Southern Denmark, Odense; Department of Biomedical Sciences (F.D., N.S., B.H.B.), Faculty of Health and Medical Sciences, University of Copenhagen; Department of Clinical Genetics (C.F.), Odense University Hospital; and Copenhagen Neuromuscular Center, Department of Neurology (J.V.), Rigshospitalet, University of Copenhagen, Denmark
| | - John Vissing
- Department of Neurology (C.K.S., D.G.), Odense University Hospital; and Department of Clinical Research (C.K.S., D.G.), Faculty of Health Sciences, University of Southern Denmark, Odense; Department of Biomedical Sciences (F.D., N.S., B.H.B.), Faculty of Health and Medical Sciences, University of Copenhagen; Department of Clinical Genetics (C.F.), Odense University Hospital; and Copenhagen Neuromuscular Center, Department of Neurology (J.V.), Rigshospitalet, University of Copenhagen, Denmark
| | - David Gaist
- Department of Neurology (C.K.S., D.G.), Odense University Hospital; and Department of Clinical Research (C.K.S., D.G.), Faculty of Health Sciences, University of Southern Denmark, Odense; Department of Biomedical Sciences (F.D., N.S., B.H.B.), Faculty of Health and Medical Sciences, University of Copenhagen; Department of Clinical Genetics (C.F.), Odense University Hospital; and Copenhagen Neuromuscular Center, Department of Neurology (J.V.), Rigshospitalet, University of Copenhagen, Denmark
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49
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Abstract
In 1993, Jabs et al. were the first to describe a genetic origin of craniosynostosis. Since this discovery, the genetic causes of the most common syndromes have been described. In 2015, a total of 57 human genes were reported for which there had been evidence that mutations were causally related to craniosynostosis. Facilitated by rapid technological developments, many others have been identified since then. Reviewing the literature, we characterize the most common craniosynostosis syndromes followed by a description of the novel causes that were identified between January 2015 and December 2017.
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Affiliation(s)
- Jacqueline A C Goos
- Department of Plastic and Reconstructive Surgery and Hand Surgery, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Irene M J Mathijssen
- Department of Plastic and Reconstructive Surgery and Hand Surgery, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
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50
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Farmakidis C, Pasnoor M, Barohn RJ, Dimachkie MM. Congenital Myasthenic Syndromes: a Clinical and Treatment Approach. Curr Treat Options Neurol 2018; 20:36. [DOI: 10.1007/s11940-018-0520-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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