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Talarico M, Fortunato F, Labalme A, Januel L, Chatron N, Sanlaville D, Sammarra I, Gagliardi M, Procopio R, Valentino P, Annesi G, Lesca G, Gambardella A. Idiopathic generalized epilepsy in a family with SCN4A-related myotonia. Epilepsia Open 2024; 9:951-959. [PMID: 38544349 PMCID: PMC11145607 DOI: 10.1002/epi4.12920] [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: 09/11/2023] [Revised: 02/01/2024] [Accepted: 02/04/2024] [Indexed: 06/04/2024] Open
Abstract
OBJECTIVES Myotonia is a clinical sign typical of a group of skeletal muscle channelopathies, the non-dystrophic myotonias. These disorders are electrophysiologically characterized by altered membrane excitability, due to specific genetic variants in known causative genes (CLCN1 and SCN4A). Juvenile Myoclonic Epilepsy (JME) is an epileptic syndrome identified as idiopathic generalized epilepsy, its genetics is complex and still unclarified. The co-occurrence of these two phenotypes is rare and the causes likely have a genetic background. In this study, we have genetically investigated an Italian family in which co-segregates myotonia, JME, or abnormal EEG without seizures was observed. METHODS All six individuals of the family, 4 affected and 2 unaffected, were clinically evaluated; EMG and EEG examinations were performed. For genetic testing, Exome Sequencing was performed for the six family members and Sanger sequencing was used to confirm the candidate variant. RESULTS Four family members, the mother and three siblings, were affected by myotonia. Moreover, EEG recordings revealed interictal generalized sharp-wave discharges in all affected individuals, and two siblings were affected by JME. All four affected members share the same identified variant, c.644 T > C, p.Ile215Thr, in SCN4A gene. Variants that could account for the epileptic phenotype alone, separately from the myotonic one, were not identified. SIGNIFICANCE These results provide supporting evidence that both myotonic and epileptic phenotypes could share a common genetic background, due to variants in SCN4A gene. SCN4A pathogenic variants, already known to be causative of myotonia, likely increase the susceptibility to epilepsy in our family. PLAIN LANGUAGE SUMMARY This study analyzed all members of an Italian family, in which the mother and three siblings had myotonia and epilepsy. Genetic analysis allowed to identify a variant in the SCN4A gene, which appears to be the cause of both clinical signs in this family.
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Affiliation(s)
- Mariagrazia Talarico
- Department of Medical and Surgical Sciences, Institute of NeurologyUniversity Magna GraeciaCatanzaroItaly
| | - Francesco Fortunato
- Department of Medical and Surgical Sciences, Institute of NeurologyUniversity Magna GraeciaCatanzaroItaly
| | | | - Louis Januel
- Genetics DepartmentHospices Civils de LyonLyonFrance
| | - Nicolas Chatron
- Genetics DepartmentHospices Civils de LyonLyonFrance
- GENDEV Team, CRNL, INSERM U1028, CNRS UMR 5292UCBL1LyonFrance
| | - Damien Sanlaville
- Genetics DepartmentHospices Civils de LyonLyonFrance
- GENDEV Team, CRNL, INSERM U1028, CNRS UMR 5292UCBL1LyonFrance
| | - Ilaria Sammarra
- Department of Medical and Surgical Sciences, Institute of NeurologyUniversity Magna GraeciaCatanzaroItaly
| | - Monica Gagliardi
- Department of Medical and Surgical Sciences, Neuroscience Research CenterMagna Graecia UniversityCatanzaroItaly
| | - Radha Procopio
- Department of Medical and Surgical Sciences, Institute of NeurologyUniversity Magna GraeciaCatanzaroItaly
| | - Paola Valentino
- Department of Medical and Surgical Sciences, Institute of NeurologyUniversity Magna GraeciaCatanzaroItaly
| | - Grazia Annesi
- Institute for Biomedical Research and InnovationNational Research CouncilCosenzaItaly
| | - Gaetan Lesca
- Genetics DepartmentHospices Civils de LyonLyonFrance
- GENDEV Team, CRNL, INSERM U1028, CNRS UMR 5292UCBL1LyonFrance
| | - Antonio Gambardella
- Department of Medical and Surgical Sciences, Institute of NeurologyUniversity Magna GraeciaCatanzaroItaly
- Department of Medical and Surgical Sciences, Neuroscience Research CenterMagna Graecia UniversityCatanzaroItaly
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Vicart S, Péréon Y, Ghorab K, Pegat A, Dufresne R, Zozulya-Weidenfeller A, Noury JB, Nadaj-Pakleza A, Tard C, Sacconi S. Self-reported outcomes and quality of life of patients with non-dystrophic myotonia: The French IMPACT 2022 survey. Rev Neurol (Paris) 2024:S0035-3787(24)00530-7. [PMID: 38811249 DOI: 10.1016/j.neurol.2024.04.007] [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: 11/21/2023] [Revised: 04/08/2024] [Accepted: 04/21/2024] [Indexed: 05/31/2024]
Abstract
Non-dystrophic myotonias (NDM) are disabling genetic diseases that impact quality of life. To reduce the impact of NDM, patients develop coping strategies such as lifestyle adaptation and avoiding key triggers. To understand how myotonia affects patients' lives, the IMPACT survey, an online questionnaire on patient-reported outcomes, was developed based on international IMPACT questionnaire. The French IMPACT 2022 survey was completed by 47 NDM French patients. Besides muscle stiffness (98%), patients reported muscle pain (83%), falls (70%) and anxiety (77%). These issues negatively impacted abilities to work/study (49%), daily life at home (49%) and overall mobility outside (49%). Most patients (96%) reported ongoing pharmacological treatment (mexiletine, 91%) associated with improvement in muscle stiffness (100%) and reduction in falls (94%), muscle pain (87%) and anxiety (80%). Patients were moderately satisfied (19.1%), satisfied (42.6%) and very satisfied (29.8%) with the current management; 32% rated their quality of life positively (≥ 8 on 10-point scale). In conclusion, this French survey confirms the impact of myotonia on daily life and quality of life. The improvement in patient-reported outcomes in treated participants highlights the importance of managing myotonia with effective treatments. More work should be initiated to assess the importance of NDM symptom management and patients' adherence and compliance to treatment.
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Affiliation(s)
- S Vicart
- National Centre for Muscle Channelopathies, Service of Neuro-Myology, University Hospital Pitié-Salpêtrière, Assistance Publique-Hôpitaux de Paris, Sorbonne University, INSERM UMR 974, Institute of Myology, 47-83 Boulevard de l'Hôpital 75013 Paris, France.
| | - Y Péréon
- Reference Centre for Neuromuscular Disorders AOC, Euro-NMD, Filnemus, CHU de Nantes, Hôtel-Dieu, 1, place Alexis-Ricordeau, 44000 Nantes, France
| | - K Ghorab
- Reference Centre for Rare Peripheral Neuropathies, CHU de Limoges, 2, avenue Martin-Luther-King, 87000 Limoges, France
| | - A Pegat
- Hospices civils de Lyon, Department of ENMG and Neuromuscular Disorders, Reference Centre of Neuromuscular Disorders, Rhône Alpes, Neurological Hospital P.-Wertheimer, 59, boulevard Pinel, 69500 Bron, France
| | - R Dufresne
- Lupin Neurosciences, Landis+Gyr Strasse 1, 6300 Zug, Switzerland
| | | | - J-B Noury
- Reference Centre for Neuromuscular Disorders AOC, Inserm, LBAI, UMR1227, CHRU de Brest, boulevard Tanguy-Prigent, 29200 Brest, France
| | - A Nadaj-Pakleza
- Reference Centre for Neuromuscular Disorders NEIdF, Euro-NMD, Department of Neurology, Filnemus, hôpitaux universitaires de Strasbourg, 1, avenue Molière, 67200 Strasbourg, France
| | - C Tard
- U1172, Reference Centre for Neuromuscular Disorders Nord/Est/Île-de-France, Department of Neurology, Cognitive-Motor Expertise Unit, CHU de Lille, rue Michel-Polonowski, 59000 Lille, France
| | - S Sacconi
- Reference Centre for Neuromuscular Disorders, CHU de Nice, 30, voie Romaine, 06000 Nice, France
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Jacobsen LN, Stemmerik MG, Skriver SV, Pedersen JJ, Løkken N, Vissing J. Contractile properties and magnetic resonance imaging-assessed fat replacement of muscles in myotonia congenita. Eur J Neurol 2024; 31:e16207. [PMID: 38270354 DOI: 10.1111/ene.16207] [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: 08/14/2023] [Revised: 12/18/2023] [Accepted: 12/28/2023] [Indexed: 01/26/2024]
Abstract
BACKGROUND AND PURPOSE Myotonia congenita (MC) is a muscle channelopathy in which pathogenic variants in a key sarcolemmal chloride channel Gene (CLCN1) cause myotonia. This study used muscle magnetic resonance imaging (MRI) to quantify contractile properties and fat replacement of muscles in a Danish cohort of MC patients. METHODS Individuals with the Thomsen (dominant) and Becker (recessive) variants of MC were studied. Isometric muscle strength, whole-body MRI, and clinical data were collected. The degree of muscle fat replacement of thigh, calf, and forearm muscles was quantitively calculated on Dixon MRI as fat fractions (FFs). Contractility was evaluated as the muscle strength per contractile muscle cross-sectional area (PT/CCSA). Muscle contractility was compared with clinical data. RESULTS Intramuscular FF was increased and contractility reduced in calf and in forearm muscles compared with controls (FF = 7.0-14.3% vs. 5.3-9.6%, PT/CCSA = 1.1-4.9 Nm/cm2 vs. 1.9-5.8 Nm/cm2 [p < 0.05]). Becker individuals also showed increased intramuscular FF and reduced contractility of thigh muscles (FF = 11.9% vs. 9.2%, PT/CCSA = 1.9 Nm/cm2 vs. 3.2 Nm/cm2 [p < 0.05]). Individual muscle analysis showed that increased FF was limited to seven of 18 examined muscles (p < 0.05). There was a weak correlation between reduced contractility and severity of symptoms. CONCLUSIONS Individuals with MC have increased fat replacement and reduced contractile properties of muscles. Nonetheless, changes were small and likely did not impact clinically on their myotonic symptoms.
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Affiliation(s)
- Laura Nørager Jacobsen
- Copenhagen Neuromuscular Center, Department of Neurology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Mads Godtfeldt Stemmerik
- Copenhagen Neuromuscular Center, Department of Neurology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Sofie Vinther Skriver
- Copenhagen Neuromuscular Center, Department of Neurology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Jonas Jalili Pedersen
- Copenhagen Neuromuscular Center, Department of Neurology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Nicoline Løkken
- Copenhagen Neuromuscular Center, Department of Neurology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - John Vissing
- Copenhagen Neuromuscular Center, Department of Neurology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
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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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Elettreby AM, Elnaga AAA, Alsaied MA, Ewis DK, Sharkawy AM, Fareed R, Alderbi GM. Effectiveness and safety of mexiletine versus placebo in patients with myotonia: a systematic review and meta-analysis. Neurol Sci 2024:10.1007/s10072-024-07412-z. [PMID: 38403671 DOI: 10.1007/s10072-024-07412-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Accepted: 02/16/2024] [Indexed: 02/27/2024]
Abstract
BACKGROUND The rare nature of dystrophic and non-dystrophic myotonia has limited the available evidence on the efficacy of mexiletine as a potential treatment. To address this gap, we conducted a systematic review and meta-analysis to evaluate the effectiveness and safety of mexiletine for both dystrophic and non-dystrophic myotonic patients. METHODS The search was conducted on various electronic databases up to March 2023, for randomized clinical trials (RCTs) comparing mexiletine versus placebo in myotonic patients. A risk of bias assessment was carried out, and relevant data was extracted manually into an online sheet. RevMan software (version 5.4) was employed for analysis. RESULTS A total of five studies, comprising 186 patients, were included in the meta-analysis. Our findings showed that mexiletine was significantly more effective than placebo in improving stiffness score (SMD = - 1.19, 95% CI [- 1.53, - 0.85]), as well as in reducing hand grip myotonia (MD = - 1.36 s, 95% CI [- 1.83, - 0.89]). Mexiletine also significantly improved SF-36 Physical and Mental Component Score in patients with non-dystrophic myotonia only. Regarding safety, mexiletine did not significantly alter ECG parameters but was associated with greater gastrointestinal symptoms (GIT) compared to placebo (RR 3.7, 95% CI [1.79, 7.64]). Other adverse events showed no significant differences. CONCLUSION The results support that mexiletine is effective and safe in myotonic patients; however, it is associated with a higher risk of GIT symptoms. Due to the scarcity of published RCTs and the prevalence of GIT symptoms, we recommend further well-designed RCTs testing various drug combinations to reduce GIT symptoms.
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Affiliation(s)
- Abdelrahman Mohammed Elettreby
- Faculty of Medicine, Mansoura University, El Gomhouria St, Mansoura, 35511, Egypt.
- Medical Research Group of Egypt, Negida Academy LLC, Arlington, MA, 02474, USA.
| | - Ahmed Abdullah Abo Elnaga
- Faculty of Medicine, Mansoura University, El Gomhouria St, Mansoura, 35511, Egypt
- Medical Research Group of Egypt, Negida Academy LLC, Arlington, MA, 02474, USA
| | - Mohamed Ahmed Alsaied
- Faculty of Medicine, Mansoura University, El Gomhouria St, Mansoura, 35511, Egypt
- Medical Research Group of Egypt, Negida Academy LLC, Arlington, MA, 02474, USA
| | - Dalia Kamal Ewis
- Medical Research Group of Egypt, Negida Academy LLC, Arlington, MA, 02474, USA
- Faculty of Medicine, Beni Suef University, Beni Suef, Egypt
| | - Aya Mohammed Sharkawy
- Medical Research Group of Egypt, Negida Academy LLC, Arlington, MA, 02474, USA
- Faculty of Medicine, South Valley University, Qena, Egypt
| | - Rahma Fareed
- Medical Research Group of Egypt, Negida Academy LLC, Arlington, MA, 02474, USA
- Faculty of Pharmacy, Beni Suef University, Beni Suef, Egypt
| | - Gehad Magdy Alderbi
- Medical Research Group of Egypt, Negida Academy LLC, Arlington, MA, 02474, USA
- Faculty of Pharmacy, Beni Suef University, Beni Suef, Egypt
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Yadav J, Barnwal R, Kumar Mandal S, Prajapati B. Acetazolamide-responsive myotonia with a novel Ile239Thr mutation in SCN4A gene: a case report. Ann Med Surg (Lond) 2024; 86:1191-1195. [PMID: 38333241 PMCID: PMC10849450 DOI: 10.1097/ms9.0000000000001673] [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: 08/16/2023] [Accepted: 12/20/2023] [Indexed: 02/10/2024] Open
Abstract
Introduction and importance Sodium channel myotonia (SCM) belongs to the group of sodium channelopathies with mutations involving SCN4A gene. The main feature of sodium channel myotonia is pure myotonia without episodes of weakness or paralysis. One of the sodium channel myotonia has been classified as acetazolamide-responsive myotonia because of the effectiveness of acetazolamide as an antimyotonic drug. Case presentation The child presented with generalized muscle hypertrophy and stiffness involving arms, thighs, calves, chest, and back muscles with unusually prominent trapezius muscle. The parents described the warm-up phenomenon as an improvement in stiffness as the day passes and with repetitive action. Percussion myotonia was illustrated in the thenar eminence and trapezius muscle. Characteristic 'dive-bomber' sound was present in electromyography, and whole-exome sequencing revealed a novel Ile239Thr mutation in the SCN4A gene. Acetazolamide was prescribed for the condition, and regular follow-up shows an excellent clinical response. Clinical discussion This case presents a pure myotonic phenotype without episodes of weakness or paralysis. Generalized myotonia with muscle hypertrophy and demonstrating warm-up phenomenon resembles myotonia congenita (a chloride channelopathy). However, genetic analysis revealed a novel Ile239Thr mutation involving SCN4A gene indicating this case to be a sodium channelopathy. Conclusion This case limelight sodium channel myotonia with a novel Ile239Thr mutation in SCN4A gene that phenotypically resembles myotonia congenita but genetically belongs to sodium channelopathy highlighting the poor correlation between genotypes and phenotypes in non-dystrophic myotonia. Acetazolamide can be a safe and cost-effective antimyotonic drug in sodium channel myotonia.
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Lidonnici D, Brambilla P, Ravasio R, Zozulya-Weidenfeller A, Beiderbeck A, van Aswegen M, Oliveira R, Sansone VA. Expert Insights from a Delphi-driven Neurologists' Panel: Real-world Mexiletine use in Patients with Myotonic Disorders in Italy. J Neuromuscul Dis 2024; 11:411-423. [PMID: 38306059 DOI: 10.3233/jnd-230115] [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
Background Myotonic disorders, such as non-dystrophic myotonias (NDMs) and myotonic dystrophies (DMs) are characterized by a delay in muscle relaxation after a contraction stimulus. There is general consensus that protocols to treat myotonia need to be implemented. Objective Mexiletine is the only pharmacological agent approved for the symptomatic treatment of myotonia in adult patients with NDM and is considered to be the first-line treatment for DMs; however, its production in Italy was halted in 2022 making its availability to patients problematic. Methods A panel of 8 Italian neurologists took part in a two-round Delphi panel between June and October 2022, analyzing the current use of mexiletine in Italian clinical practice. Results The panelists assist 1126 patients (69% DM type1, 18% NDM and 13% DM type2). Adult NDM patients receive, on average, 400-600 mg of mexiletine hydrochloride (HCl) while adult DM patients receive 100-600 mg, per day in the long-term. The severity of symptoms is considered the main reason to start mexiletine treatment for both NDM and DM patients. Mexiletine is reckoned to have a clinical impact for both NDM and DM patients, but currently drug access is problematic. Conclusions Mexiletine treatment is recognized to have a role in the reduction of the symptomatic burden for NDM and DM patients. Patient management could be improved by facilitating access to therapy and developing new drug formulations.
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Affiliation(s)
| | | | | | | | | | | | | | - Valeria A Sansone
- The NEMO Center, Neurorehabilitation Unit, University of Milan, ASST Niguarda Hospital, Milan, Italy
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Qaisar R. Targeting neuromuscular junction to treat neuromuscular disorders. Life Sci 2023; 333:122186. [PMID: 37858716 DOI: 10.1016/j.lfs.2023.122186] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2023] [Revised: 10/07/2023] [Accepted: 10/16/2023] [Indexed: 10/21/2023]
Abstract
The integrity and preservation of the neuromuscular junction (NMJ), the interface between the motor neuron and skeletal muscle, is critical for maintaining a healthy skeletal muscle. The structural and/or functional defects in the three cellular components of NMJ, namely the pre-synaptic terminal, synaptic cleft, and post-synaptic region, negatively affect skeletal muscle mass and/or strength. Therefore, NMJ repair appears to be an appropriate therapy for muscle disorders. Mouse models provide a detailed molecular characterization of various cellular components of NMJ with relevance to human diseases. This review discusses different molecular targets on the three cellular components of NMJ for treating muscle diseases. The potential effects of these therapies on NMJ morphology and motor performance, their therapeutic efficacy, and clinical relevance are discussed. Collectively, the available data supports targeting NMJ alone or as an adjunct therapy in treating muscle disorders. However, the potential impact of such interventions on human patients with muscle disorders requires further investigation.
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Affiliation(s)
- Rizwan Qaisar
- Basic Medical Sciences, College of Medicine, University of Sharjah, Sharjah, United Arab Emirates; Space Medicine Research Group, Sharjah Institute for Medical and Health Sciences, University of Sharjah, Sharjah 27272, United Arab Emirates; Cardiovascular Research Group, Sharjah Institute for Medical and Health Sciences, University of Sharjah, Sharjah 27272, United Arab Emirates.
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Brenes O, Pusch M, Morales F. ClC-1 Chloride Channel: Inputs on the Structure-Function Relationship of Myotonia Congenita-Causing Mutations. Biomedicines 2023; 11:2622. [PMID: 37892996 PMCID: PMC10604815 DOI: 10.3390/biomedicines11102622] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Revised: 08/11/2023] [Accepted: 08/24/2023] [Indexed: 10/29/2023] Open
Abstract
Myotonia congenita is a hereditary muscle disease mainly characterized by muscle hyperexcitability, which leads to a sustained burst of discharges that correlates with the magnitude and duration of involuntary aftercontractions, muscle stiffness, and hypertrophy. Mutations in the chloride voltage-gated channel 1 (CLCN1) gene that encodes the skeletal muscle chloride channel (ClC-1) are responsible for this disease, which is commonly known as myotonic chloride channelopathy. The biophysical properties of the mutated channel have been explored and analyzed through in vitro approaches, providing important clues to the general function/dysfunction of the wild-type and mutated channels. After an exhaustive search for CLCN1 mutations, we report in this review more than 350 different mutations identified in the literature. We start discussing the physiological role of the ClC-1 channel in skeletal muscle functioning. Then, using the reported functional effects of the naturally occurring mutations, we describe the biophysical and structural characteristics of the ClC-1 channel to update the knowledge of the function of each of the ClC-1 helices, and finally, we attempt to point out some patterns regarding the effects of mutations in the different helices and loops of the protein.
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Affiliation(s)
- Oscar Brenes
- Departamento de Fisiología, Escuela de Medicina, Universidad de Costa Rica, San José 11501-2060, Costa Rica;
- Centro de Investigación en Neurociencias (CIN), Universidad de Costa Rica, San José 11501-2060, Costa Rica
| | - Michael Pusch
- Istituto di Biofisica, Consiglio Nazionale delle Ricerche (CNR), Via De Marini 6, 16149 Genova, Italy
| | - Fernando Morales
- Instituto de Investigaciones en Salud (INISA), Universidad de Costa Rica, San José 11501-2060, Costa Rica
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Velardo D, Antognozzi S, Rimoldi M, Pagliarani S, Cogiamanian F, Barbieri S, Corti S, Comi GP, Ronchi D. Case report: Clinical and molecular characterization of two siblings affected by Brody myopathy. Front Neurol 2023; 14:1170071. [PMID: 37332993 PMCID: PMC10272758 DOI: 10.3389/fneur.2023.1170071] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Accepted: 05/16/2023] [Indexed: 06/20/2023] Open
Abstract
Exercise-induced muscle stiffness is the hallmark of Brody disease, an autosomal recessive myopathy due to biallelic pathogenic variants in ATP2A1, encoding the sarcoplasmic/endoplasmic reticulum Ca2+ ATPase SERCA1. About 40 patients have been reported so far. Our knowledge about the natural history of this disorder, genotype-phenotype correlations and the effect of symptomatic treatment is partial. This results in incomplete recognition and underdiagnosis of the disease. Here, we report the clinical, instrumental, and molecular features of two siblings presenting childhood-onset exercise-induced muscle stiffness without pain. Both the probands display difficulty in climbing stairs and running, frequent falls, delayed muscle relaxation after exertion. Cold temperatures worsen these symptoms. No myotonic discharges were observed at electromyography. Whole Exome Sequencing analysis in the probands revealed the presence of two ATP2A1 variants: the previously reported frameshift microdeletion c.2464delC and the likely pathogenic novel splice-site variant c.324 + 1G > A, whose detrimental effect was demonstrated in ATP2A1 transcript analysis. The bi-allelic inheritance was verified by Sanger sequencing in the unaffected parents. This study expands the molecular defects associated with Brody myopathy.
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Affiliation(s)
- Daniele Velardo
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Neuromuscular and Rare Disease Unit, Milan, Italy
| | - Sara Antognozzi
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Neurology Unit, Milan, Italy
| | - Martina Rimoldi
- Dino Ferrari Center, Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy
| | - Serena Pagliarani
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Neurology Unit, Milan, Italy
| | - Filippo Cogiamanian
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Neurophysiology Unit, Milan, Italy
| | - Sergio Barbieri
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Neurophysiology Unit, Milan, Italy
| | - Stefania Corti
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Neurology Unit, Milan, Italy
- Dino Ferrari Center, Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy
| | - Giacomo Pietro Comi
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Neuromuscular and Rare Disease Unit, Milan, Italy
- Dino Ferrari Center, Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy
| | - Dario Ronchi
- Dino Ferrari Center, Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy
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Vacchiano V, Brugnoni R, Campanale C, Imbrici P, Dinoi G, Canioni E, Laghetti P, Saltarella I, Altamura C, Maggi L, Liguori R, Donadio V, Desaphy JF. Coexistence of SCN4A and CLCN1 mutations in a family with atypical myotonic features: A clinical and functional study. Exp Neurol 2023; 362:114342. [PMID: 36720299 DOI: 10.1016/j.expneurol.2023.114342] [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: 11/06/2022] [Revised: 01/12/2023] [Accepted: 01/26/2023] [Indexed: 01/30/2023]
Abstract
Non-dystrophic myotonias include several entities with possible clinical overlap, i.e. myotonia congenita caused by CLCN1 gene mutations, as well as paramyotonia congenita and sodium channel myotonia caused by SCN4A gene mutations. Herein, we describe the clinical features of five relatives affected by clinical and neurophysiological myotonia, with an aspecific and mixed phenotype. Next-generation sequencing identified the novel p.K1302R variant in SCN4A and the p.H838P variant in CLCN1. Segregation of the two mutations with the disease was confirmed by genotyping affected and non-affected family members. Patch-clamp experiments showed that sodium currents generated by p.K1302R and WT hNav1.4 were very similar. Mutant channel showed a small negative shift (5 mV) in the voltage-dependence of activation, which increased the likelihood of the channel to open at more negative voltages. The p.H838P mutation caused a reduction in chloride current density and a small voltage-dependence shift towards less negative potentials, in agreement with its position into the CBS2 domain of the C-terminus. Our results demonstrated that the mild functional alterations induced by p.K1302R and p.H838P in combination may be responsible for the mixed myotonic phenotypes. The K1302R mutant was sensitive to mexiletine and lamotrigine, suggesting that both drugs might be useful for the K1302R carriers.
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Affiliation(s)
- Veria Vacchiano
- IRCSS Istituto delle Scienze Neurologiche di Bologna, Bologna, Italy.
| | - Raffaella Brugnoni
- Neuroimmunology and Neuromuscular Diseases Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Italy
| | - Carmen Campanale
- Dept. of Precision and Regenerative Medicine, School of Medicine, University of Bari Aldo Moro, Bari, Italy
| | - Paola Imbrici
- Dept. of Pharmacy - Drug Sciences, University of Bari Aldo Moro, Bari, Italy
| | - Giorgia Dinoi
- Dept. of Pharmacy - Drug Sciences, University of Bari Aldo Moro, Bari, Italy
| | - Eleonora Canioni
- Neuroimmunology and Neuromuscular Diseases Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Italy
| | - Paola Laghetti
- Dept. of Precision and Regenerative Medicine, School of Medicine, University of Bari Aldo Moro, Bari, Italy
| | - Ilaria Saltarella
- Dept. of Precision and Regenerative Medicine, School of Medicine, University of Bari Aldo Moro, Bari, Italy
| | - Concetta Altamura
- Dept. of Precision and Regenerative Medicine, School of Medicine, University of Bari Aldo Moro, Bari, Italy
| | - Lorenzo Maggi
- Neuroimmunology and Neuromuscular Diseases Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Italy
| | - Rocco Liguori
- IRCSS Istituto delle Scienze Neurologiche di Bologna, Bologna, Italy
| | - Vincenzo Donadio
- IRCSS Istituto delle Scienze Neurologiche di Bologna, Bologna, Italy
| | - Jean-François Desaphy
- Dept. of Precision and Regenerative Medicine, School of Medicine, University of Bari Aldo Moro, Bari, Italy
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12
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Detecting impaired muscle relaxation in myopathies with the use of motor cortical stimulation. Neuromuscul Disord 2023; 33:396-404. [PMID: 37030055 DOI: 10.1016/j.nmd.2023.03.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Revised: 03/01/2023] [Accepted: 03/02/2023] [Indexed: 03/06/2023]
Abstract
Impaired muscle relaxation is a notable feature in specific myopathies. Transcranial magnetic stimulation (TMS) of the motor cortex can induce muscle relaxation by abruptly halting corticospinal drive. Our aim was to quantify muscle relaxation using TMS in different myopathies with symptoms of muscle stiffness, contractures/cramps, and myalgia and explore the technique's diagnostic potential. In men, normalized peak relaxation rate was lower in Brody disease (n = 4) (-3.5 ± 1.3 s-1), nemaline myopathy type 6 (NEM6; n = 5) (-7.5 ± 1.0 s-1), and myotonic dystrophy type 2 (DM2; n = 5) (-10.2 ± 2.0 s-1) compared to healthy (n = 14) (-13.7 ± 2.1 s-1; all P ≤ 0.01) and symptomatic controls (n = 9) (-13.7 ± 1.6 s-1; all P ≤ 0.02). In women, NEM6 (n = 5) (-5.7 ± 2.1 s-1) and McArdle patients (n = 4) (-6.6 ± 1.4 s-1) had lower relaxation rate compared to healthy (n = 10) (-11.7 ± 1.6 s-1; both P ≤ 0.002) and symptomatic controls (n = 8) (-11.3 ± 1.8 s-1; both P ≤ 0.008). TMS-induced muscle relaxation achieved a high level of diagnostic accuracy (area under the curve = 0.94 (M) and 0.92 (F)) to differentiate symptomatic controls from myopathy patients. Muscle relaxation assessed using TMS has the potential to serve as a diagnostic tool, an in-vivo functional test to confirm the pathogenicity of unknown variants, an outcome measure in clinical trials, and monitor disease progression.
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13
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Pedersen JJ, Stemmerik MG, Jacobsen LN, Skriver SV, Wilms GR, Duno M, Vissing J. Muscle fat replacement and contractility in patients with skeletal muscle sodium channel disorders. Sci Rep 2023; 13:2538. [PMID: 36782059 PMCID: PMC9925746 DOI: 10.1038/s41598-023-29759-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Accepted: 02/09/2023] [Indexed: 02/15/2023] Open
Abstract
Skeletal muscle sodium channel disorders give rise to episodic symptoms such as myotonia and/or periodic paralysis. Chronic symptoms with permanent weakness are not considered characteristic of the phenotypes. Muscle fat replacement represents irreversible damage that inevitably will impact on muscle strength. This study investigates muscle fat replacement and contractility in patients with pathogenic SCN4A variants compared to healthy controls. T1-weighted and 2-point Dixon MRI of the legs were conducted to assess fat replacement. Stationary dynamometry was used to assess muscle strength. Contractility was determined by maximal muscle contraction divided by cross-sectional muscle area. The average cross-sectional intramuscular fat fraction was greater in patients compared with controls by 2.5% in the calves (95% CI 0.74-4.29%, p = 0.007) and by 2.0% in the thighs (95% CI 0.75-3.2%, p = 0.003). Muscle contractility was less in patients vs. controls by 14-27% (p < 0.05). Despite greater fat fraction and less contractility, absolute strength was not significantly less. This study quantitatively documents greater fat fraction and additionally describes difference in muscle contractility in a large cohort of patients with skeletal muscle sodium channel disorders. The clinical impact of these abnormal findings is likely limited as muscle hypertrophy in the patients served to preserve absolute muscle strength. Subgroup analysis indicated significant difference in phenotype by genotype, however these findings lack statistical significance and serve as inspiration for future researchers to probe into the geno- phenotype relationship in these disorders.Trial registration: The study was registered at http://clinicaltrials.gov (identifier: NCT04808388).
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Affiliation(s)
- Jonas Jalili Pedersen
- Copenhagen Neuromuscular Center, Department of Neurology, Rigshospitalet, University of Copenhagen, Inge Lehmanns Vej 7-9, 2100, Copenhagen, Denmark.
| | - Mads Godtfeldt Stemmerik
- Copenhagen Neuromuscular Center, Department of Neurology, Rigshospitalet, University of Copenhagen, Inge Lehmanns Vej 7-9, 2100, Copenhagen, Denmark
| | - Laura Nørager Jacobsen
- Copenhagen Neuromuscular Center, Department of Neurology, Rigshospitalet, University of Copenhagen, Inge Lehmanns Vej 7-9, 2100, Copenhagen, Denmark
| | - Sofie Vinther Skriver
- Copenhagen Neuromuscular Center, Department of Neurology, Rigshospitalet, University of Copenhagen, Inge Lehmanns Vej 7-9, 2100, Copenhagen, Denmark
| | - Gustav Rhode Wilms
- Copenhagen Neuromuscular Center, Department of Neurology, Rigshospitalet, University of Copenhagen, Inge Lehmanns Vej 7-9, 2100, Copenhagen, Denmark
| | - Morten Duno
- Clinical Genetic Laboratory, Department of Biochemical Genetics, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - John Vissing
- Copenhagen Neuromuscular Center, Department of Neurology, Rigshospitalet, University of Copenhagen, Inge Lehmanns Vej 7-9, 2100, Copenhagen, Denmark
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14
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Musa NH, Thilakavathy K, Mohamad NA, Kennerson ML, Inche Mat LN, Loh WC, Abdul Rashid AM, Baharin J, Ibrahim A, Wan Sulaiman WA, Hoo FK, Basri H, Yusof Khan AHK. Case report: Incomplete penetrance of autosomal dominant myotonia congenita caused by a rare CLCN1 variant c.1667T>A (p.I556N) in a Malaysian family. Front Genet 2023; 13:972007. [PMID: 36659963 PMCID: PMC9842662 DOI: 10.3389/fgene.2022.972007] [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: 06/17/2022] [Accepted: 09/23/2022] [Indexed: 01/04/2023] Open
Abstract
Myotonia congenita (MC) is a rare neuromuscular disease caused by mutations within the CLCN1 gene encoding skeletal muscle chloride channels. MC is characterized by delayed muscle relaxation during contraction, resulting in muscle stiffness. There is a lack of MC case reports and data on the prevalence among Malaysians. We report a clinical case of a 50-year-old woman presents with muscle stiffness and cramp episodes that started in early childhood. She had difficulty initiating muscle movement and presented with transient muscle weakness after rest, which usually improved after repeated contraction (warm-up phenomenon). She was diagnosed with MC after myotonic discharge on electromyography (EMG). Her brother had similar symptoms; however, no additional family members showed MC symptoms. Serum creatine kinase levels were elevated in both the proband and her brother with 447 U/L and 228 U/L recorded, respectively. Genetic analysis by whole-exome sequencing (WES) revealed a previously reported pathogenic CLCN1 gene variant c.1667T>A (p.I556N). Genetic screening of all family members revealed that the same variant was observed in the children of both the proband and her brother; however, the children did not present with either clinical or electrophysiological MC symptoms. The multiplex ligation-dependent probe amplification (MLPA) analysis conducted identified neither exon deletion nor duplication in CLCN1. In conclusion, this report describes the first case of MC in Malaysia in which incomplete penetrance observed in this family is caused by a known pathogenic CLCN1 variant.
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Affiliation(s)
- Nurul Huda Musa
- Department of Biomedical Science, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Serdang, Malaysia,Centre of Foundation Studies, Universiti Teknologi MARA, Cawangan Selangor, Kampus Dengkil, Dengkil, Selangor, Malaysia
| | - Karuppiah Thilakavathy
- Department of Biomedical Science, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Serdang, Malaysia,Genetics and Regenerative Research Group, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Serdang, Malaysia,*Correspondence: Abdul Hanif Khan Yusof Khan, ; Karuppiah Thilakavathy,
| | - Nur Afiqah Mohamad
- Department of Neurology, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Serdang, Malaysia,Center for Foundation Studies, Foundation in Science, Lincoln University College, Petaling Jaya, Malaysia
| | - Marina L. Kennerson
- Northcott Neuroscience Laboratory, ANZAC Research Institute, Sydney Local Health District, Faculty of Medicine and Health, University of Sydney, Sydney, NSW, Australia,Molecular Medicine Laboratory, Concord Hospital, Concord, NSW, Australia
| | - Liyana Najwa Inche Mat
- Department of Neurology, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Serdang, Malaysia
| | - Wei Chao Loh
- Department of Neurology, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Serdang, Malaysia
| | - Anna Misyail Abdul Rashid
- Department of Neurology, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Serdang, Malaysia
| | - Janudin Baharin
- Department of Neurology, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Serdang, Malaysia
| | - Azliza Ibrahim
- Department of Neurology, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Serdang, Malaysia
| | - Wan Aliaa Wan Sulaiman
- Department of Neurology, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Serdang, Malaysia
| | - Fan Kee Hoo
- Department of Neurology, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Serdang, Malaysia
| | - Hamidon Basri
- Department of Neurology, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Serdang, Malaysia
| | - Abdul Hanif Khan Yusof Khan
- Department of Neurology, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Serdang, Malaysia,*Correspondence: Abdul Hanif Khan Yusof Khan, ; Karuppiah Thilakavathy,
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15
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Molenaar JP, van Zandvoort E, van Engelen BG, Voermans NC, Doorduin J. Reproducibility and robustness of motor cortical stimulation to assess muscle relaxation kinetics. Physiol Rep 2022; 10:e15491. [PMID: 36267028 PMCID: PMC9585355 DOI: 10.14814/phy2.15491] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Accepted: 09/26/2022] [Indexed: 11/06/2022] Open
Abstract
Transcranial magnetic stimulation (TMS) of the motor cortex can be used during a voluntary contraction to inhibit corticospinal drive to the muscle and consequently induce involuntary muscle relaxation. Our aim was to evaluate the reproducibility and the effect of varying experimental conditions (robustness) of TMS‐induced muscle relaxation. Relaxation of deep finger flexors was assessed in 10 healthy subjects (5 M, 5 F) using handgrip dynamometry with normalized peak relaxation rate as main outcome measure, that is, peak relaxation rate divided by (voluntary plus TMS‐evoked)force prior to relaxation. Both interday and interrater reliability of relaxation rate were high with intraclass correlation coefficient of 0.88 and 0.92 and coefficient of variation of 3.8 and 3.7%, respectively. Target forces of 37.5% of maximal voluntary force or higher resulted in similar relaxation rate. From 50% of maximal stimulator output and higher relaxation rate remained the same. Only the most lateral position (>2 cm from the vertex) rendered lower relaxation rate (mean ± SD: 11.1 ± 3.0 s−1, 95% CI: 9.0–13.3 s−1) compared to stimulation at the vertex (12.8 ± 1.89 s−1, 95% CI: 11.6–14.1 s−1). Within the range of baseline skin temperatures, an average change of 0.5 ± 0.2 s−1 in normalized peak relaxation rate was measured per 1°C change in skin temperature. In conclusion, interday and interrater reproducibility and reliability of TMS‐induced muscle relaxation of the finger flexors were high. Furthermore, this technique is robust with limited effect of target force, stimulation intensity, and coil position. Muscle relaxation is strongly affected by skin temperature; however, this effect is marginal within the normal skin temperature range. We deem this technique well suited for clinical and scientific assessment of muscle relaxation.
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Affiliation(s)
- Joery P. Molenaar
- Department of Neurology, Donders Institute for Brain, Cognition and BehaviourRadboud University Medical CenterNijmegenThe Netherlands,Department of NeurologyRijnstateArnhemThe Netherlands
| | - Elianne van Zandvoort
- Department of Neurology, Donders Institute for Brain, Cognition and BehaviourRadboud University Medical CenterNijmegenThe Netherlands
| | - Baziel G. van Engelen
- Department of Neurology, Donders Institute for Brain, Cognition and BehaviourRadboud University Medical CenterNijmegenThe Netherlands
| | - Nicol C. Voermans
- Department of Neurology, Donders Institute for Brain, Cognition and BehaviourRadboud University Medical CenterNijmegenThe Netherlands
| | - Jonne Doorduin
- Department of Neurology, Donders Institute for Brain, Cognition and BehaviourRadboud University Medical CenterNijmegenThe Netherlands
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16
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Cordenier A, Flamez A, de Ravel T, Gheldof A, Pannone L, De Asmundis C, Pappaert G, Bissay V. Case report: Coexistence of myotonia congenita and Brugada syndrome in one family. Front Neurol 2022; 13:1011956. [PMID: 36212636 PMCID: PMC9537820 DOI: 10.3389/fneur.2022.1011956] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Accepted: 09/05/2022] [Indexed: 11/21/2022] Open
Abstract
Myotonia congenita is a rare neuromuscular disorder caused by CLCN1 mutations resulting in delayed muscle relaxation. Extramuscular manifestations are not considered to be present in chloride skeletal channelopathies, although recently some cardiac manifestations have been described. We report a family with autosomal dominant myotonia congenita and Brugada syndrome. Bearing in mind the previously reported cases of cardiac arrhythmias in myotonia congenita patients, we discuss the possible involvement of the CLCN1-gene mutations in primary cardiac arrhythmia.
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Affiliation(s)
- Ann Cordenier
- Department of Neurology, Center for Neurosciences, Vrije Universiteit Brussel (VUB), UZ-Brussel, Brussels, Belgium
- *Correspondence: Ann Cordenier
| | - Anja Flamez
- Department of Neurology, Center for Neurosciences, Vrije Universiteit Brussel (VUB), UZ-Brussel, Brussels, Belgium
| | - Thomy de Ravel
- Center for Medical Genetics, Vrije Universiteit Brussel (VUB), UZ-Brussel, Brussels, Belgium
| | - Alexander Gheldof
- Center for Medical Genetics, Vrije Universiteit Brussel (VUB), UZ-Brussel, Brussels, Belgium
| | - Luigi Pannone
- Heart Rhythm Management Centre, Vrije Universiteit Brussel (VUB), UZ-Brussel, Brussels, Belgium
| | - Carlo De Asmundis
- Heart Rhythm Management Centre, Vrije Universiteit Brussel (VUB), UZ-Brussel, Brussels, Belgium
| | - Gudrun Pappaert
- Heart Rhythm Management Centre, Vrije Universiteit Brussel (VUB), UZ-Brussel, Brussels, Belgium
| | - Véronique Bissay
- Department of Neurology, Center for Neurosciences, Vrije Universiteit Brussel (VUB), UZ-Brussel, Brussels, Belgium
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17
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Woelfel C, Meurs K, Friedenberg S, DeBruyne N, Olby NJ. A novel mutation of the CLCN1 gene in a cat with myotonia congenita: Diagnosis and treatment. Vet Med (Auckl) 2022; 36:1454-1459. [PMID: 35815860 PMCID: PMC9308434 DOI: 10.1111/jvim.16471] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Accepted: 05/27/2022] [Indexed: 11/29/2022]
Abstract
Case Description A 10‐month‐old castrated male domestic longhair cat was evaluated for increasing frequency of episodic limb rigidity. Clinical Findings The cat presented for falling over and lying recumbent with its limbs in extension for several seconds when startled or excited. Upon examination, the cat had hypertrophied musculature, episodes of facial spasm, and a short‐strided, stiff gait. Diagnostics Electromyography (EMG) identified spontaneous discharges that waxed and waned in amplitude and frequency, consistent with myotonic discharges. A high impact 8‐base pair (bp) deletion across the end of exon 3 and intron 3 of the chloride voltage‐gated channel 1 (CLCN1) gene was identified using whole genome sequencing. Treatment and Outcome Phenytoin treatment was initiated at 3 mg/kg po q24 h and resulted in long‐term improvement. Clinical Relevance This novel mutation within the CLCN1 gene is a cause of myotonia congenita in cats and we report for the first time its successful treatment.
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Affiliation(s)
- Christian Woelfel
- College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina, USA
| | - Kathryn Meurs
- College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina, USA
| | - Steven Friedenberg
- Veterinary Medical Center, University of Minnesota, Saint Paul, Minnesota, USA
| | - Nicole DeBruyne
- College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina, USA
| | - Natasha J Olby
- College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina, USA
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18
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Fullam TR, Chandrashekhar S, Farmakidis C, Jawdat O, Pasnoor M, Dimachkie MM, Statland JM. Non-dystrophic myotonia: 2-year clinical and patient reported outcomes. Muscle Nerve 2022; 66:148-158. [PMID: 35644941 PMCID: PMC9308727 DOI: 10.1002/mus.27649] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 05/24/2022] [Accepted: 05/25/2022] [Indexed: 11/06/2022]
Abstract
INTRODUCTION/AIMS Consistency of differences between non-dystrophic myotonias over time measured by standardized clinical/patient-reported outcomes is lacking. Evaluation of longitudinal data could establish clinically relevant endpoints for future research. METHODS Data from prospective observational study of 95 definite/clinically suspected non-dystrophic myotonia participants (six sites in the United States, United Kingdom, and Canada) between March 2006 and March 2009 were analyzed. Outcomes included: standardized symptom interview/exam, Short Form-36, Individualized Neuromuscular Quality of Life (INQoL), electrophysiological short/prolonged exercise tests, manual muscle testing, quantitative grip strength, modified get-up-and-go test. Patterns were assigned as described by Fournier et al. Comparisons were restricted to confirmed sodium channelopathies (SCN4A, baseline, year 1, year 2: n = 34, 19, 13), chloride channelopathies (CLCN1, n = 32, 26, 18), and myotonic dystrophy type 2 (DM2, n = 9, 6, 2). RESULTS Muscle stiffness was the most frequent symptom over time (54.7%-64.7%). Eyelid myotonia and paradoxical handgrip/eyelid myotonia were more frequent in SCN4A. Grip strength and combined manual muscle testing remained stable. Modified get-up-and-go showed less warm up in SCN4A but remained stable. Median post short exercise decrement was stable, except for SCN4A (baseline to year 2 decrement difference 16.6% [Q1, Q3: 9.5, 39.2]). Fournier patterns type 2 (CLCN1) and 1 (SCN4A) were most specific; 40.4% of participants had a change in pattern over time. INQoL showed higher impact for SCN4A and DM2 with scores stable over time. DISCUSSION Symptom frequency and clinical outcome assessments were stable with defined variability in myotonia measures supporting trial designs like cross over or combined n-of-1 as important for rare disorders.
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Affiliation(s)
- Timothy R Fullam
- Department of Neurology, University of Kansas Medical Center, Kansas City, Kansas, USA.,Department of Neurology, Brooke Army Medical Center, JBSA-Fort Sam, Houston, Texas, USA
| | - Swathy Chandrashekhar
- Department of Neurology, University of Kansas Medical Center, Kansas City, Kansas, USA
| | | | - Omar Jawdat
- Department of Neurology, University of Kansas Medical Center, Kansas City, Kansas, USA
| | - Mamatha Pasnoor
- Department of Neurology, University of Kansas Medical Center, Kansas City, Kansas, USA
| | - Mazen M Dimachkie
- Department of Neurology, University of Kansas Medical Center, Kansas City, Kansas, USA
| | - Jeffrey M Statland
- Department of Neurology, University of Kansas Medical Center, Kansas City, Kansas, USA
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19
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Wang Q, Zhao Z, Shen H, Bing Q, Li N, Hu J. The Clinical, Myopathological, and Genetic Analysis of 20 Patients With Non-dystrophic Myotonia. Front Neurol 2022; 13:830707. [PMID: 35350395 PMCID: PMC8957821 DOI: 10.3389/fneur.2022.830707] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Accepted: 01/25/2022] [Indexed: 11/29/2022] Open
Abstract
Introduction Non-dystrophic myotonias (NDMs) are skeletal muscle ion channelopathies caused by CLCN1 or SCN4A mutations. This study aimed to describe the clinical, myopathological, and genetic analysis of NDM in a large Chinese cohort. Methods We reviewed the clinical manifestations, laboratory results, electrocardiogram, electromyography, muscle biopsy, genetic analysis, treatment, and follow-up of 20 patients (from 18 families) with NDM. Results Cases included myotonia congenita (MC, 17/20) and paramyotonia congenita (PMC, 3/20). Muscle stiffness and hypertrophy, grip and percussion myotonia, and the warm-up phenomenon were frequently observed in MC and PMC patients. Facial stiffness, eye closure myotonia, and cold sensitivity were more common in PMC patients and could be accompanied by permanent weakness. Nine MC patients and two PMC patients had cardiac abnormalities, mainly manifested as cardiac arrhythmia, and the father of one patient died of sudden cardiac arrest. Myotonic runs in electromyography were found in all patients, and seven MC patients had mild myopathic changes. There was no difference in muscle pathology between MC and PMC patients, most of whom had abnormal muscle fiber type distribution or selective muscle fiber atrophy. Nineteen CLCN1 variants were found in 17 MC patients, among which c.795T>G (p.D265E) was a new variant, and two SCN4A variants were found in three PMC patients. The patients were treated with mexiletine and/or carbamazepine, and the symptoms of myotonia were partially improved. Conclusions MC and PMC have considerable phenotypic overlap. Genetic investigation contributes to identifying the subtype of NDM. The muscle pathology of NDM lacks specific changes.
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Affiliation(s)
- Quanquan Wang
- Department of Neuromuscular Disorders, The Third Hospital of Hebei Medical University, Shijiazhuang, China.,Department of Neurology, Qilu Hospital of Shandong University, Qingdao, China
| | - Zhe Zhao
- Department of Neuromuscular Disorders, The Third Hospital of Hebei Medical University, Shijiazhuang, China
| | - Hongrui Shen
- Department of Neuromuscular Disorders, The Third Hospital of Hebei Medical University, Shijiazhuang, China
| | - Qi Bing
- Department of Neuromuscular Disorders, The Third Hospital of Hebei Medical University, Shijiazhuang, China
| | - Nan Li
- Department of Neuromuscular Disorders, The Third Hospital of Hebei Medical University, Shijiazhuang, China
| | - Jing Hu
- Department of Neuromuscular Disorders, The Third Hospital of Hebei Medical University, Shijiazhuang, China
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20
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Nan H, Wu Y, Cui S, Sun H, Wang J, Li Y, Meng L, Nagasaka T, Wu L. Coexistence of Charcot-Marie-Tooth 1A and nondystrophic myotonia due to PMP22 duplication and SCN4A pathogenic variants: a case report. BMC Neurol 2022; 22:17. [PMID: 34996390 PMCID: PMC8740465 DOI: 10.1186/s12883-021-02538-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Accepted: 12/27/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Charcot-Marie-Tooth disease (CMT) is a genetically heterogeneous hereditary neuropathy, and CMT1A is the most common form; it is caused by a duplication of the peripheral myelin protein 22 (PMP22) gene. Mutations in the transient sodium channel Nav1.4 alpha subunit (SCN4A) gene underlie a diverse group of dominantly inherited nondystrophic myotonias that run the spectrum from subclinical myopathy to severe muscle stiffness, disabling weakness, or frank episodes of paralysis. CASE PRESENTATION We describe a Chinese family affected by both CMT1A and myotonia with concomitant alterations in both the PMP22 and SCN4A genes. In this family, the affected proband inherited the disease from his father in an autosomal dominant manner. Genetic analysis confirmed duplication of the PMP22 gene and a missense c.3917G > C (p. Gly1306Ala) mutation in SCN4A in both the proband and his father. The clinical phenotype in the proband showed the combined involvement of skeletal muscle and peripheral nerves. Electromyography showed myopathic changes, including myotonic discharges. MRI revealed the concurrence of neurogenic and myogenic changes in the lower leg muscles. Sural nerve biopsies revealed a chronic demyelinating and remyelinating process with onion bulb formations in the proband. The proband's father presented with confirmed subclinical myopathy, very mild distal atrophy and proximal hypertrophy of the lower leg muscles, pes cavus, and areflexia. CONCLUSION This study reports the coexistence of PMP22 duplication and SCN4A mutation. The presenting features in this family suggested that both neuropathy and myopathy were inherited in an autosomal dominant manner. The proband had a typical phenotype of sodium channel myotonia (SCM) and CMT1A. However, his father with the same mutations presented a much milder clinical phenotype. Our study might expand the genetic and phenotypic spectra of neuromuscular disorders with concomitant mutations.
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Affiliation(s)
- Haitian Nan
- Department of Neurology, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Yunqing Wu
- Department of Neurology, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | - Shilei Cui
- Department of Neurology, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | - Houliang Sun
- Department of Neurology, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | - Jiawei Wang
- Department of Neurology, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | - Ying Li
- Department of Neurology, Peking University First Hospital, Beijing, China
| | - Lingchao Meng
- Department of Neurology, Peking University First Hospital, Beijing, China
| | - Takamura Nagasaka
- Department of Neurology, University of Yamanashi, 1110 Shimokato, Chuo-city, Yamanashi, 409-3898, Japan
| | - Liyong Wu
- Department of Neurology, Xuanwu Hospital, Capital Medical University, Beijing, China.
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21
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Treatment and Management of Disorders of Neuromuscular Hyperexcitability and Periodic Paralysis. Neuromuscul Disord 2022. [DOI: 10.1016/b978-0-323-71317-7.00018-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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22
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Chapman AM, Schurer M, Weijers L, Omar A, Lee H, Weidenfeller AZ, Ellis C, Sonecha S, Schneider-Gold C. Improving the understanding of how patients with non-dystrophic myotonia are selected for myotonia treatment with mexiletine (NaMuscla): outcomes of treatment impact using a European Delphi panel. BMC Neurol 2021; 21:467. [PMID: 34852780 PMCID: PMC8633892 DOI: 10.1186/s12883-021-02491-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Accepted: 11/10/2021] [Indexed: 11/17/2022] Open
Abstract
Background Non-dystrophic myotonias (NDMs) comprise muscle chloride and sodium channelopathies due to genetic defects of the CLCN1- and SCN4A-channels. No licensed antimyotonic treatment has been available until approval of mexiletine (NaMuscla®) for adult patients by the EMA in December 2018. This Delphi panel aimed to understand how outcomes of the pivotal phase III Mexiletine study (MYOMEX) translate to real world practice and investigate health resource use, quality of life and the natural history of NDM to support economic modelling and facilitate patient access. Methods Nine clinical experts in treating NDM took part in a two-round Delphi panel. Their knowledge of NDM and previous use of mexiletine as an off-label treatment prior to NaMuscla’s approval ensured they could provide both qualitative context and quantitative estimates to support economic modelling comparing mexiletine (NaMuscla) to best supportive care. Consensus in four key areas was sought: healthcare resource utilization (HRU), treatment with mexiletine (NaMuscla), patient quality of life (QoL), and the natural history of disease. Concept questions were also asked, considering perceptions on the feasibility of mapping the validated Individualized Neuromuscular Quality of Life (INQoL) instrument to the generic EQ-5D™, and the potential impact on caregiver QoL. Results Consensus was achieved for key questions including the average long-term dosage of mexiletine (NaMuscla) in practice, the criteria for eligibility of myotonia treatment, the clinical importance of QoL outcomes in MYOMEX, the higher proportion of patients with increased QoL, and the reduction in the need for mental health resources for patients receiving mexiletine (NaMuscla). While consensus was not achieved for other questions, the results demonstrated that most experts felt mexiletine (NaMuscla) reduced the need for HRU and was expected to improve QoL. The QoL mapping exercise suggested that it is feasible to map domains of INQoL to EQ-5D. Points of interest for future research were identified, including that mexiletine (NaMuscla) may slow the annual decrease in QoL of patients over their lifetime, and a significant negative impact on QoL for some caregivers. Conclusions This project successfully provided data from an informed group of clinical experts, complementing the currently available clinical trial data for mexiletine (NaMuscla) to support patient access decisions. Supplementary Information The online version contains supplementary material available at 10.1186/s12883-021-02491-3.
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Affiliation(s)
| | | | | | - Amer Omar
- Lupin Atlantis Holdings SA, Zug, Switzerland
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23
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Mousele C, Matthews E, Pitceathly RDS, Hanna MG, MacDonald S, Savvatis K, Carr A, Turner C. Long-term Safety and Efficacy of Mexiletine in Myotonic Dystrophy Types 1 and 2. Neurol Clin Pract 2021; 11:e682-e685. [PMID: 34840883 PMCID: PMC8610501 DOI: 10.1212/cpj.0000000000001073] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Accepted: 02/10/2021] [Indexed: 11/15/2022]
Abstract
BACKGROUND AND OBJECTIVE Myotonic dystrophy types 1 and 2 are progressive multisystem genetic disorders whose core clinical feature is myotonia. Mexiletine, an antagonist of voltage-gated sodium channels, is a recommended antimyotonic agent in the nondystrophic myotonias, but its use in myotonic dystrophy is limited because of lack of data regarding its long-term efficacy and safety profile. METHODS To address this issue, this study retrospectively evaluated patients with myotonic dystrophy receiving mexiletine over a mean time period of 32.9 months (range 0.1-216 months). RESULTS This study demonstrated that 96% of patients reported some improvement in myotonia symptoms with mexiletine treatment. No clinically relevant cardiac adverse events were associated with the long-term use of mexiletine. CONCLUSIONS These findings support that mexiletine is both safe and effective when used long-term in myotonic dystrophy. CLASSIFICATION OF EVIDENCE This study provides Class IV evidence that mexiletine is a well-tolerated and effective treatment for myotonic dystrophy types 1 and 2.
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Affiliation(s)
- Christina Mousele
- UCL Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery (CM); Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery (EM, RDSP, MGH, AC, CT); The National Hospital for Neurology and Neurosurgery (SM), Atkinson-Morley Neuromuscular Centre (EM); and Inherited Cardiovascular Diseases Unit, Barts Health Centre, Barts Healthcare NHS Trust (KS), London, United Kingdom
| | - Emma Matthews
- UCL Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery (CM); Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery (EM, RDSP, MGH, AC, CT); The National Hospital for Neurology and Neurosurgery (SM), Atkinson-Morley Neuromuscular Centre (EM); and Inherited Cardiovascular Diseases Unit, Barts Health Centre, Barts Healthcare NHS Trust (KS), London, United Kingdom
| | - Robert D S Pitceathly
- UCL Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery (CM); Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery (EM, RDSP, MGH, AC, CT); The National Hospital for Neurology and Neurosurgery (SM), Atkinson-Morley Neuromuscular Centre (EM); and Inherited Cardiovascular Diseases Unit, Barts Health Centre, Barts Healthcare NHS Trust (KS), London, United Kingdom
| | - Michael G Hanna
- UCL Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery (CM); Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery (EM, RDSP, MGH, AC, CT); The National Hospital for Neurology and Neurosurgery (SM), Atkinson-Morley Neuromuscular Centre (EM); and Inherited Cardiovascular Diseases Unit, Barts Health Centre, Barts Healthcare NHS Trust (KS), London, United Kingdom
| | - Susan MacDonald
- UCL Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery (CM); Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery (EM, RDSP, MGH, AC, CT); The National Hospital for Neurology and Neurosurgery (SM), Atkinson-Morley Neuromuscular Centre (EM); and Inherited Cardiovascular Diseases Unit, Barts Health Centre, Barts Healthcare NHS Trust (KS), London, United Kingdom
| | - Konstantinos Savvatis
- UCL Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery (CM); Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery (EM, RDSP, MGH, AC, CT); The National Hospital for Neurology and Neurosurgery (SM), Atkinson-Morley Neuromuscular Centre (EM); and Inherited Cardiovascular Diseases Unit, Barts Health Centre, Barts Healthcare NHS Trust (KS), London, United Kingdom
| | - Aisling Carr
- UCL Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery (CM); Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery (EM, RDSP, MGH, AC, CT); The National Hospital for Neurology and Neurosurgery (SM), Atkinson-Morley Neuromuscular Centre (EM); and Inherited Cardiovascular Diseases Unit, Barts Health Centre, Barts Healthcare NHS Trust (KS), London, United Kingdom
| | - Christopher Turner
- UCL Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery (CM); Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery (EM, RDSP, MGH, AC, CT); The National Hospital for Neurology and Neurosurgery (SM), Atkinson-Morley Neuromuscular Centre (EM); and Inherited Cardiovascular Diseases Unit, Barts Health Centre, Barts Healthcare NHS Trust (KS), London, United Kingdom
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Rigamonti A, Mantero V, Peverelli L, Pagliarani S, Lucchiari S, Comi G, Gibertini S, Salmaggi A. p.Asn1180Ile mutation of SCN4A gene in an Italian family with myopathy and myotonic syndrome. Neurol Sci 2021; 42:5359-5363. [PMID: 34378097 DOI: 10.1007/s10072-021-05537-z] [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: 04/29/2021] [Accepted: 08/01/2021] [Indexed: 11/28/2022]
Abstract
INTRODUCTION Mutations of the skeletal muscle sodium channel gene SCN4A are associated with several neuromuscular disorders including hyper/hypokaliemic periodic paralysis, paramyotonia congenita and sodium channel myotonia. These disorders are distinguished from dystrophic myotonias by the absence of progressive weakness and extramuscular systemic involvement. METHODS We present an Italian family with 2 subjects carrying a p.Asn1180Ile mutation in SCN4A gene showing a peculiar clinical picture characterized by the association of myopathic features and myotonia. RESULTS The clinical, electromyographic and histological findings of these patients are reported. The possible pathogenicity of the mutation was tested by three different software, all giving positive results. DISCUSSION This is the first report of a dominant, heterozygous mutation in SCN4A causing a complex phenotype of non-congenital myopathy and myotonic syndrome. We suggest that, in patients with myotonia and myopathy not related to dystrophic myotonias, the sequence analysis of SCN4A gene should be performed.
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Affiliation(s)
- Andrea Rigamonti
- Neurology Unit, Ospedale A. Manzoni, ASST Lecco, Via Dell'Eremo 9-11, 23900, Lecco, Italy.
| | - Vittorio Mantero
- Neurology Unit, Ospedale A. Manzoni, ASST Lecco, Via Dell'Eremo 9-11, 23900, Lecco, Italy
| | - Lorenzo Peverelli
- Neurology Unit, Ospedale Maggiore di Lodi, ASST Lodi, Largo Donatori del Sangue 1, 26900, Lodi, Italy
| | - Serena Pagliarani
- Dino Ferrari Centre, Neuroscience Section, Department of Pathophysiology and Transplantation (DEPT), University of Milan, Via F. Sforza 35, 20122, Milano, Italy
| | - Sabrina Lucchiari
- Dino Ferrari Centre, Neuroscience Section, Department of Pathophysiology and Transplantation (DEPT), University of Milan, Via F. Sforza 35, 20122, Milano, Italy
| | - Giacomo Comi
- Neuromuscular and Rare Diseases Unit, Foundation IRCSS Ca' Granda Ospedale Maggiore Policlinico, Via F. Sforza 35, 20122, Milano, Italy
| | - Sara Gibertini
- Muscle Cell Biology Laboratory, Neuromuscular Diseases and Neuroimmunology Unit, Fondazione IRCCS Istituto Neurologico "C. Besta", Via Celoria 11, 20133, Milano, Italy
| | - Andrea Salmaggi
- Neurology Unit, Ospedale A. Manzoni, ASST Lecco, Via Dell'Eremo 9-11, 23900, Lecco, Italy
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25
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Vicart S, Franques J, Bouhour F, Magot A, Péréon Y, Sacconi S, Nadaj-Pakleza A, Behin A, Zahr N, Hézode M, Fournier E, Payan C, Lacomblez L, Fontaine B. Efficacy and safety of mexiletine in non-dystrophic myotonias: A randomised, double-blind, placebo-controlled, cross-over study. Neuromuscul Disord 2021; 31:1124-1135. [PMID: 34702654 DOI: 10.1016/j.nmd.2021.06.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 06/11/2021] [Accepted: 06/22/2021] [Indexed: 11/30/2022]
Abstract
The MYOMEX study was a multicentre, randomised, double-blind, placebo-controlled, cross-over study aimed to compare the effects of mexiletine vs. placebo in patients with myotonia congenita (MC) and paramyotonia congenita (PC). The primary endpoint was the self-reported score of stiffness severity on a 100 mm visual analogic scale (VAS). Mexiletine treatment started at 200 mg/day and was up-titrated by 200 mg increment each three days to reach a maximum dose of 600 mg/day for total treatment duration of 18 days for each cross-over period. The modified intent-to-treat population included 25 patients (13 with MC and 12 with PC; mean age, 43.0 years; male, 68.0%). The median VAS score for mexiletine was 71.0 at baseline and decreased to 16.0 at the end of the treatment while the score did not change for placebo (81.0 at baseline vs. 78.0 at end of treatment). A mixed effects linear model analysis on ranked absolute changes showed a significant effect of treatment (p < 0.001). The overall score of the Individualized Neuromuscular Quality of Life questionnaire (INQoL) was significantly improved (p < 0.001). No clinically significant adverse events were reported. In conclusion, mexiletine improved stiffness and quality of life in patients with nondystrophic myotonia and was well tolerated.
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Affiliation(s)
- Savine Vicart
- Assistance Publique-Hôpitaux de Paris, Sorbonne Université, INSERM, Service of Neuro-Myology, Muscle Channelopathies Reference Center and UMR 974, Institute of Myology, University Hospital Pitié-Salpêtrière, Paris, France.
| | - Jérôme Franques
- Assistance Publique-Hôpitaux de Marseille, Department of Neurology and Neuromuscular Diseases, La Timone Hospital, Marseille, France
| | - Françoise Bouhour
- Electroneuromyography and Neuromuscular Disorders Department, Hospices Civils de Lyon, University Hospital of Lyon, France
| | - Armelle Magot
- Reference Centre for Neuromuscular disorders AOC, University Hospital, Hôtel-Dieu, Nantes, France
| | - Yann Péréon
- Reference Centre for Neuromuscular disorders AOC, University Hospital, Hôtel-Dieu, Nantes, France
| | - Sabrina Sacconi
- Université Côte d'Azur, Peripheral Nervous System & Muscle Department, Pasteur 2 Hospital, Centre Hospitalier Universitaire de Nice, Nice, France
| | - Aleksandra Nadaj-Pakleza
- Reference Centre for Neuromuscular disorders AOC, Neurology Department, University Hospital of Angers, Angers, France
| | - Anthony Behin
- Assistance Publique-Hôpitaux de Paris, Service of Neuro-Myology, Reference Centre for Neuromuscular disorders NEIdF, University Hospital Pitié-Salpêtrière, Paris, France
| | - Noël Zahr
- Assistance Publique-Hôpitaux de Paris, Sorbonne Université, Pharmacology Department, University Hospital Pitié-Salpêtrière, Paris, France
| | - Marianne Hézode
- Assistance Publique-Hôpitaux de Paris, Sorbonne Université, Department of Clinical Neurophysiology, University Hospital Pitié-Salpêtrière, Paris, France
| | - Emmanuel Fournier
- Assistance Publique-Hôpitaux de Paris, Sorbonne Université, Department of Clinical Neurophysiology, University Hospital Pitié-Salpêtrière, Paris, France
| | - Christine Payan
- Assistance Publique-Hôpitaux de Paris, Sorbonne Université, Pharmacology Department, University Hospital Pitié-Salpêtrière, Paris, France
| | - Lucette Lacomblez
- Assistance Publique-Hôpitaux de Paris, Sorbonne Université, Pharmacology Department, University Hospital Pitié-Salpêtrière, Paris, France; Assistance Publique-Hôpitaux de Paris, Sorbonne Université, INSERM U 1422, Neurology Department, University Hospital Pitié-Salpêtrière, Paris, France
| | - Bertrand Fontaine
- Assistance Publique-Hôpitaux de Paris, Sorbonne Université, INSERM, Service of Neuro-Myology, Muscle Channelopathies Reference Center and UMR 974, Institute of Myology, University Hospital Pitié-Salpêtrière, Paris, France
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26
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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: 9] [Impact Index Per Article: 3.0] [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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27
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Lo YL. Effect of Focal Traumatic Injury in Nondystrophic Myotonic Disorders. J Clin Neuromuscul Dis 2021; 22:234-236. [PMID: 34019012 DOI: 10.1097/cnd.0000000000000323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Affiliation(s)
- Y L Lo
- National Neuroscience Institute, Singapore Duke-NUS Medical School, Singapore
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28
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Sun J, Luo S, Suetterlin KJ, Song J, Huang J, Zhu W, Xi J, Zhou L, Lu J, Lu J, Zhao C, Hanna MG, Männikkö R, Matthews E, Qiao K. Clinical and genetic spectrum of a Chinese cohort with SCN4A gene mutations. Neuromuscul Disord 2021; 31:829-838. [PMID: 33965302 DOI: 10.1016/j.nmd.2021.03.014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 03/02/2021] [Accepted: 03/31/2021] [Indexed: 10/21/2022]
Abstract
Skeletal muscle sodium channelopathies due to SCN4A gene mutations have a broad clinical spectrum. However, each phenotype has been reported in few cases of Chinese origin. We present detailed phenotype and genotype data from a cohort of 40 cases with SCN4A gene mutations seen in neuromuscular diagnostic service in Huashan hospital, Fudan University. Cases were referred from 6 independent provinces from 2010 to 2018. A questionnaire covering demographics, precipitating factors, episodes of paralysis and myotonia was designed to collect the clinical information. Electrodiagnostic studies and muscle MRI were retrospectively analyzed. The clinical spectrum of patients included: 6 Hyperkalemic periodic paralysis (15%), 18 Hypokalemic periodic paralysis (45%), 7 sodium channel myotonia (17.5%), 4 paramyotonia congenita (10%) and 5 heterozygous asymptomatic mutation carriers (12.5%). Review of clinical information highlights a significant delay to diagnosis (median 15 years), reports of pain and myalgia in the majority of patients, male predominance, circadian rhythm and common precipitating factors. Electrodiagnostic studies revealed subclinical myotonic discharges and a positive long exercise test in asymptomatic carriers. Muscle MRI identified edema and fatty infiltration in gastrocnemius and soleus. A total of 13 reported and 2 novel SCN4A mutations were identified with most variants distributed in the transmembrane helix S4 to S6, with a hotspot mutation p.Arg675Gln accounting for 32.5% (13/40) of the cohort. Our study revealed a higher proportion of periodic paralysis in SCN4A-mutated patients compared with cohorts from England and the Netherlands. It also highlights the importance of electrodiagnostic studies in diagnosis and segregation studies.
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Affiliation(s)
- J Sun
- Department of Neurology, Huashan Hospital, Fudan University, Shanghai, 200040, China
| | - S Luo
- Department of Neurology, Huashan Hospital, Fudan University, Shanghai, 200040, China; Department of Neurology, North Huashan Hospital, Fudan University, Shanghai, 200003, China
| | - K J Suetterlin
- Department of Neuromuscular Diseases, Queen Square Institute of Neurology, UCL, London, WC1N 3BG, United Kingdom
| | - J Song
- Department of Neurology, Huashan Hospital, Fudan University, Shanghai, 200040, China
| | - J Huang
- Department of Clinical Electrophysiology, Institute of Neurology, Huashan Hospital, Fudan University, Shanghai, 200040, China
| | - W Zhu
- Department of Neurology, Huashan Hospital, Fudan University, Shanghai, 200040, China
| | - J Xi
- Department of Neurology, Huashan Hospital, Fudan University, Shanghai, 200040, China
| | - L Zhou
- Department of Neurology, Huashan Hospital, Fudan University, Shanghai, 200040, China
| | - J Lu
- Department of Neurology, Huashan Hospital, Fudan University, Shanghai, 200040, China
| | - J Lu
- Department of Neurology, Huashan Hospital, Fudan University, Shanghai, 200040, China
| | - C Zhao
- Department of Neurology, Huashan Hospital, Fudan University, Shanghai, 200040, China
| | - M G Hanna
- Department of Neuromuscular Diseases, Queen Square Institute of Neurology, UCL, London, WC1N 3BG, United Kingdom
| | - R Männikkö
- Department of Neuromuscular Diseases, Queen Square Institute of Neurology, UCL, London, WC1N 3BG, United Kingdom
| | - E Matthews
- Department of Neuromuscular Diseases, Queen Square Institute of Neurology, UCL, London, WC1N 3BG, United Kingdom; Atkinson Morley Neuromuscular Centre, Regional Neurosciences Centre, Department of Neurology, St George's University Hospitals NHS Foundation Trust, London, United Kingdom
| | - K Qiao
- Department of Clinical Electrophysiology, Institute of Neurology, Huashan Hospital, Fudan University, Shanghai, 200040, China.
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29
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Brenes O, Barbieri R, Vásquez M, Vindas-Smith R, Roig J, Romero A, del Valle G, Bermúdez-Guzmán L, Bertelli S, Pusch M, Morales F. Functional and Structural Characterization of ClC-1 and Na v1.4 Channels Resulting from CLCN1 and SCN4A Mutations Identified Alone and Coexisting in Myotonic Patients. Cells 2021; 10:cells10020374. [PMID: 33670307 PMCID: PMC7918176 DOI: 10.3390/cells10020374] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 01/13/2021] [Accepted: 01/13/2021] [Indexed: 11/25/2022] Open
Abstract
Non-dystrophic myotonias have been linked to loss-of-function mutations in the ClC-1 chloride channel or gain-of-function mutations in the Nav1.4 sodium channel. Here, we describe a family with members diagnosed with Thomsen’s disease. One novel mutation (p.W322*) in CLCN1 and one undescribed mutation (p.R1463H) in SCN4A are segregating in this family. The CLCN1-p.W322* was also found in an unrelated family, in compound heterozygosity with the known CLCN1-p.G355R mutation. One reported mutation, SCN4A-p.T1313M, was found in a third family. Both CLCN1 mutations exhibited loss-of-function: CLCN1-p.W322* probably leads to a non-viable truncated protein; for CLCN1-p.G355R, we predict structural damage, triggering important steric clashes. The SCN4A-p.R1463H produced a positive shift in the steady-state inactivation increasing window currents and a faster recovery from inactivation. These gain-of-function effects are probably due to a disruption of interaction R1463-D1356, which destabilizes the voltage sensor domain (VSD) IV and increases the flexibility of the S4-S5 linker. Finally, modelling suggested that the p.T1313M induces a strong decrease in protein flexibility on the III-IV linker. This study demonstrates that CLCN1-p.W322* and SCN4A-p.R1463H mutations can act alone or in combination as inducers of myotonia. Their co-segregation highlights the necessity for carrying out deep genetic analysis to provide accurate genetic counseling and management of patients.
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Affiliation(s)
- Oscar Brenes
- Departamento de Fisiología, Escuela de Medicina, Universidad de Costa Rica, 11501 San José, Costa Rica;
- Centro de Investigación en Neurociencias (CIN), Universidad de Costa Rica, 11501 San José, Costa Rica
| | | | - Melissa Vásquez
- Instituto de Investigaciones en Salud (INISA), Universidad de Costa Rica, 11501 San José, Costa Rica; (M.V.); (R.V.-S.); (J.R.)
| | - Rebeca Vindas-Smith
- Instituto de Investigaciones en Salud (INISA), Universidad de Costa Rica, 11501 San José, Costa Rica; (M.V.); (R.V.-S.); (J.R.)
| | - Jeffrey Roig
- Instituto de Investigaciones en Salud (INISA), Universidad de Costa Rica, 11501 San José, Costa Rica; (M.V.); (R.V.-S.); (J.R.)
| | - Adarli Romero
- Escuela de Biología, Universidad de Costa Rica, 11501 San José, Costa Rica;
| | - Gerardo del Valle
- Laboratorio de Neurofisiología (Neurolab), 11801 San José, Costa Rica;
| | - Luis Bermúdez-Guzmán
- Sección de Genética y Biotecnología, Escuela de Biología, Universidad de Costa Rica, 11501 San José, Costa Rica;
| | - Sara Bertelli
- Istituto di Biofisica, CNR, 16149 Genova, Italy; (R.B.); (S.B.)
- Scuola Internazionale Superiore di Studi Avanzati (SISSA), 34136 Trieste, Italy
| | - Michael Pusch
- Istituto di Biofisica, CNR, 16149 Genova, Italy; (R.B.); (S.B.)
- Correspondence: (M.P.); (F.M.); Tel.: +39-0106475-553/522 (M.P.); +506-2511-2124 (F.M.)
| | - Fernando Morales
- Instituto de Investigaciones en Salud (INISA), Universidad de Costa Rica, 11501 San José, Costa Rica; (M.V.); (R.V.-S.); (J.R.)
- Correspondence: (M.P.); (F.M.); Tel.: +39-0106475-553/522 (M.P.); +506-2511-2124 (F.M.)
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Non-dystrophic myotonias: clinical and mutation spectrum of 70 German patients. J Neurol 2020; 268:1708-1720. [PMID: 33263785 PMCID: PMC8068660 DOI: 10.1007/s00415-020-10328-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Revised: 11/09/2020] [Accepted: 11/19/2020] [Indexed: 12/17/2022]
Abstract
Introduction Non-dystrophic myotonias (NDM) are heterogeneous diseases caused by mutations in CLCN1 and SCN4A. The study aimed to describe the clinical and genetic spectrum of NDM in a large German cohort. Methods We retrospectively identified all patients with genetically confirmed NDM diagnosed in our center. The following data were analyzed: demographics, family history, muscular features, cardiac involvement, CK, EMG, genotype, other tested genes, treatment perceived efficacy. Results 70 patients (age 40.2 years ± 14.9; 52.8% males) were included in our study (48 NDM-CLCN1, 22 NDM-SCN4A). The most frequent presenting symptoms were myotonia (NDM-CLCN1 83.3%, NDM-SCN4A 72.2%) and myalgia (NDM-CLCN1 57.4%, NDM-SCN4A 52.6%). Besides a more prominent facial involvement in NDM-SCN4A and cold-sensitivity in NDM-CLCN1, no other significant differences were observed between groups. Cardiac arrhythmia or conduction defects were documented in sixNDM-CLCN1 patients (three of them requiring a pacemaker) and one patient with NDM-SCN4A. CK was normal in 40% of patients. Myotonic runs in EMG were detected in 89.1% of CLCN1 and 78.9% of SCN4A. 50% of NDM-CLCN1 patients had the classic c.2680C>T (p.Arg894*) mutation. 12 new genetic variants are reported. About 50% of patients were not taking any anti-myotonic drug at the last follow-up. The anti-myotonic drugs with the best patient’s perceived efficacy were mexiletine and lamotrigine. Conclusion This study highlights the relevant clinical overlap between NDM-CLCN1 and NDM-SCN4A patients and warrants the use of early and broad genetic investigation for the precise identification of the NDM subtype. Besides the clinical and genetic heterogeneity, the limited response to current anti-myotonic drugs constitutes a continuing challenge. Supplementary Information The online version contains supplementary material available at 10.1007/s00415-020-10328-1.
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Zaganas I, Mastorodemos V, Spilioti M, Mathioudakis L, Latsoudis H, Michaelidou K, Kotzamani D, Notas K, Dimitrakopoulos K, Skoula I, Ioannidis S, Klothaki E, Erimaki S, Stavropoulos G, Vassilikos V, Amoiridis G, Efthimiadis G, Evangeliou A, Mitsias P. Genetic cause of heterogeneous inherited myopathies in a cohort of Greek patients. Mol Genet Metab Rep 2020; 25:100682. [PMID: 33304817 PMCID: PMC7711282 DOI: 10.1016/j.ymgmr.2020.100682] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2020] [Revised: 11/13/2020] [Accepted: 11/13/2020] [Indexed: 02/07/2023] Open
Abstract
Inherited muscle disorders are caused by pathogenic changes in numerous genes. Herein, we aimed to investigate the etiology of muscle disease in 24 consecutive Greek patients with myopathy suspected to be genetic in origin, based on clinical presentation and laboratory and electrophysiological findings and absence of known acquired causes of myopathy. Of these, 16 patients (8 females, median 24 years-old, range 7 to 67 years-old) were diagnosed by Whole Exome Sequencing as suffering from a specific type of inherited muscle disorder. Specifically, we have identified causative variants in 6 limb-girdle muscular dystrophy genes (6 patients; ANO5, CAPN3, DYSF, ISPD, LAMA2, SGCA), 3 metabolic myopathy genes (4 patients; CPT2, ETFDH, GAA), 1 congenital myotonia gene (1 patient; CLCN1), 1 mitochondrial myopathy gene (1 patient; MT-TE) and 3 other myopathy-associated genes (4 patients; CAV3, LMNA, MYOT). In 6 additional family members affected by myopathy, we reached genetic diagnosis following identification of a causative variant in an index patient. In our patients, genetic diagnosis ended a lengthy diagnostic process and, in the case of Multiple acyl-CoA dehydrogenase deficiency and Pompe's disease, it enabled specific treatment to be initiated. These results further expand the genotypic and phenotypic spectrum of inherited myopathies.
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Affiliation(s)
- Ioannis Zaganas
- Neurogenetics Laboratory, Medical School, University of Crete, Heraklion, Crete, Greece.,Neurology Department, University Hospital of Crete, Heraklion, Crete, Greece
| | | | - Martha Spilioti
- AHEPA General Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Lambros Mathioudakis
- Neurogenetics Laboratory, Medical School, University of Crete, Heraklion, Crete, Greece
| | - Helen Latsoudis
- Neurogenetics Laboratory, Medical School, University of Crete, Heraklion, Crete, Greece
| | - Kleita Michaelidou
- Neurogenetics Laboratory, Medical School, University of Crete, Heraklion, Crete, Greece
| | - Dimitra Kotzamani
- Neurogenetics Laboratory, Medical School, University of Crete, Heraklion, Crete, Greece
| | - Konstantinos Notas
- AHEPA General Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | | | - Irene Skoula
- Neurogenetics Laboratory, Medical School, University of Crete, Heraklion, Crete, Greece
| | - Stefanos Ioannidis
- Neurology Department, University Hospital of Crete, Heraklion, Crete, Greece
| | - Eirini Klothaki
- Neurology Department, University Hospital of Crete, Heraklion, Crete, Greece
| | - Sophia Erimaki
- Neurophysiology Unit, University Hospital of Crete, Heraklion, Crete, Greece
| | - Georgios Stavropoulos
- Hippokratio General Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Vassilios Vassilikos
- Hippokratio General Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Georgios Amoiridis
- Neurophysiology Unit, University Hospital of Crete, Heraklion, Crete, Greece
| | - Georgios Efthimiadis
- AHEPA General Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Athanasios Evangeliou
- Papageorgiou General Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Panayiotis Mitsias
- Neurology Department, University Hospital of Crete, Heraklion, Crete, Greece.,Neurophysiology Unit, University Hospital of Crete, Heraklion, Crete, Greece.,Department of Neurology, Henry Ford Hospital/Wayne State University, Detroit, Michigan, USA
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32
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Taminato T, Mori-Yoshimura M, Miki J, Sasaki R, Sato N, Oya Y, Nishino I, Takahashi Y. Paramyotonia Congenita with Persistent Distal and Facial Muscle Weakness: A Case Report with Literature Review. J Neuromuscul Dis 2020; 7:193-201. [PMID: 32083589 DOI: 10.3233/jnd-190440] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND Paramyotonia congenita (PC; OMIM 168300) is a non-dystrophic myotonia caused by mutations in the SCN4A gene. Transient muscle stiffness, usually induced by exposure to cold and aggravated by exercise, is the predominant clinical symptom, and interictal persistent weakness is uncommon. CASE REPORT We report a family with a history of PC accompanied by persistent hand muscle weakness with masticatory muscle involvement. Persistent weakness was exacerbated with age, and MR analysis showed marked atrophy of temporal, masseter, and finger flexor muscles with fatty replacement. The PC causative mutation T1313M in the SCN4A gene was prevalent in the family. Administration of acetazolamide chloride improved clinical symptoms and the results of cold and short exercise tests. Phenotypic variation within the family was remarkable, as the two younger affected patients did not present with persistent weakness or muscle atrophy. CONCLUSIONS PC associated with the T1313M mutation is a possible cause of persistent distal hand weakness.
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Affiliation(s)
- Tomoya Taminato
- Department of Neurology, National Center Hospital, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Madoka Mori-Yoshimura
- Department of Neurology, National Center Hospital, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Jun Miki
- Department of Neurology, Saku Central Hospital, Nagano Prefectural Federation of Agricultural Cooperatives for Health and Welfare, Nagano, Japan
| | - Ryogen Sasaki
- Department of Neurology, Kuwana City Medical Center, Mie, Japan
| | - Noriko Sato
- Department of Radiology, National Center Hospital, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Yasushi Oya
- Department of Neurology, National Center Hospital, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Ichizo Nishino
- Department of Genome Medicine Development, Medical Genome Center, National Center of Neurology and Psychiatry, Tokyo, Japan.,Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Yuji Takahashi
- Department of Neurology, National Center Hospital, National Center of Neurology and Psychiatry, Tokyo, Japan
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33
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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: 46] [Impact Index Per Article: 11.5] [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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Abstract
Skeletal muscle channelopathies are rare genetic neuromuscular conditions that include the nondystrophic myotonias and periodic paralyses. They cause disabling muscle symptoms and can limit educational potential, work opportunities, socialization, and quality of life. Effective therapy is available, making it essential to recognize and treat this group of disorders. Here, the authors highlight important aspects regarding diagnosis and management using illustrative case reports.
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Affiliation(s)
- Vinojini Vivekanandam
- Department of Neuromuscular Diseases, Queen Square Centre for Neuromuscular Diseases, UCL Queen Square Institute of Neurology and National Hospital for Neurology and Neurosurgery, London WC1N 3BG, UK
| | - Pinki Munot
- Dubowitz Neuromuscular Centre, Great Ormond Street Hospital for Children, London, UK
| | - Michael G Hanna
- Department of Neuromuscular Diseases, Queen Square Centre for Neuromuscular Diseases, UCL Queen Square Institute of Neurology and National Hospital for Neurology and Neurosurgery, London WC1N 3BG, UK
| | - Emma Matthews
- Department of Neuromuscular Diseases, Queen Square Centre for Neuromuscular Diseases, UCL Queen Square Institute of Neurology and National Hospital for Neurology and Neurosurgery, London WC1N 3BG, UK.
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Maggi L, Brugnoni R, Canioni E, Tonin P, Saletti V, Sola P, Piccinelli SC, Colleoni L, Ferrigno P, Pini A, Masson R, Manganelli F, Lietti D, Vercelli L, Ricci G, Bruno C, Tasca G, Pizzuti A, Padovani A, Fusco C, Pegoraro E, Ruggiero L, Ravaglia S, Siciliano G, Morandi L, Dubbioso R, Mongini T, Filosto M, Tramacere I, Mantegazza R, Bernasconi P. Clinical and Molecular Spectrum of Myotonia and Periodic Paralyses Associated With Mutations in SCN4A in a Large Cohort of Italian Patients. Front Neurol 2020; 11:646. [PMID: 32849172 PMCID: PMC7403394 DOI: 10.3389/fneur.2020.00646] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Accepted: 05/29/2020] [Indexed: 11/25/2022] Open
Abstract
Background: Four main clinical phenotypes have been traditionally described in patients mutated in SCN4A, including sodium-channel myotonia (SCM), paramyotonia congenita (PMC), Hypokaliemic type II (HypoPP2), and Hyperkaliemic/Normokaliemic periodic paralysis (HyperPP/NormoPP); in addition, rare phenotypes associated with mutations in SCN4A are congenital myasthenic syndrome and congenital myopathy. However, only scarce data have been reported in literature on large patient cohorts including phenotypes characterized by myotonia and episodes of paralysis. Methods: We retrospectively investigated clinical and molecular features of 80 patients fulfilling the following criteria: (1) clinical and neurophysiological diagnosis of myotonia, or clinical diagnosis of PP, and (2) presence of a pathogenic SCN4A gene variant. Patients presenting at birth with episodic laryngospasm or congenital myopathy-like phenotype with later onset of myotonia were considered as neonatal SCN4A. Results: PMC was observed in 36 (45%) patients, SCM in 30 (37.5%), Hyper/NormoPP in 7 (8.7%), HypoPP2 in 3 (3.7%), and neonatal SCN4A in 4 (5%). The median age at onset was significantly earlier in PMC than in SCM (p < 0.01) and in Hyper/NormoPP than in HypoPP2 (p = 0.02). Cold-induced myotonia was more frequently observed in PMC (n = 34) than in SCM (n = 23) (p = 0.04). No significant difference was found in age at onset of episodes of paralysis among PMC and PP or in frequency of permanent weakness between PP (n = 4), SCM (n = 5), and PMC (n = 10). PP was more frequently associated with mutations in the S4 region of the NaV1.4 channel protein compared to SCM and PMC (p < 0.01); mutations causing PMC were concentrated in the C-terminal region of the protein, while SCM-associated mutations were detected in all the protein domains. Conclusions: Our data suggest that skeletal muscle channelopathies associated with mutations in SCN4A represent a continuum in the clinical spectrum.
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Affiliation(s)
- Lorenzo Maggi
- Neuroimmunology and Neuromuscular Diseases, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Raffaella Brugnoni
- Neuroimmunology and Neuromuscular Diseases, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Eleonora Canioni
- Neuroimmunology and Neuromuscular Diseases, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Paola Tonin
- Section of Clinical Neurology, Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Veronica Saletti
- Developmental Neurology Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Patrizia Sola
- Clinica Neurologica, Azienda Ospedaliero Universitaria di Modena, Modena, Italy
| | - Stefano Cotti Piccinelli
- Unit of Neurology, Center for Neuromuscular Diseases, ASST Spedali Civili and University of Brescia, Brescia, Italy
| | - Lara Colleoni
- Neuroimmunology and Neuromuscular Diseases, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Paola Ferrigno
- SC Neurologia e Stroke Unit, Azienda Ospedaliera Brotzu, Cagliari, Italy
| | - Antonella Pini
- Child Neurology and Psychiatry Unit, IRCCS Istituto delle Scienze Neurologiche di Bologna, Bologna, Italy
| | - Riccardo Masson
- Developmental Neurology Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Fiore Manganelli
- Department of Neurosciences, Reproductive Sciences and Odontostomatology, University of Naples "Federico II", Naples, Italy
| | | | - Liliana Vercelli
- Department of Neurosciences Rita Levi Montalcini, University of Turin, Turin, Italy
| | - Giulia Ricci
- Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Claudio Bruno
- Center of Translational and Experimental Myology, Istituto Giannina Gaslini, Genova, Italy
| | - Giorgio Tasca
- Unità Operativa Complessa di Neurologia, Dipartimento di Scienze Dell'Invecchiamento, Neurologiche, Ortopediche e della Testa-Collo, Fondazione Policlinico Universitario A. Gemelli IRCCS, Rome, Italy
| | - Antonio Pizzuti
- Fondazione IRCCS Casa Sollievo della Sofferenza, Laboratory of Medical Genetics, San Giovanni Rotondo, Italy.,Department of Experimental Medicine, Sapienza University of Rome, Rome, Italy
| | - Alessandro Padovani
- Unit of Neurology, Center for Neuromuscular Diseases, ASST Spedali Civili and University of Brescia, Brescia, Italy
| | - Carlo Fusco
- Dipartimento Materno-Infantile, S.C. Neuropsichiatria Infantile, Presidio Ospedaliero Provinciale Santa Maria Nuova, IRCCS di Reggio Emilia, Reggio Emilia, Italy
| | - Elena Pegoraro
- Department of Neurosciences, University of Padova, Padova, Italy
| | - Lucia Ruggiero
- Department of Neurosciences, Reproductive Sciences and Odontostomatology, University of Naples "Federico II", Naples, Italy
| | | | - Gabriele Siciliano
- Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Lucia Morandi
- Neuroimmunology and Neuromuscular Diseases, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Raffaele Dubbioso
- Department of Neurosciences, Reproductive Sciences and Odontostomatology, University of Naples "Federico II", Naples, Italy
| | - Tiziana Mongini
- Department of Neurosciences Rita Levi Montalcini, University of Turin, Turin, Italy
| | - Massimiliano Filosto
- Unit of Neurology, Center for Neuromuscular Diseases, ASST Spedali Civili and University of Brescia, Brescia, Italy
| | - Irene Tramacere
- Research and Clinical Development Department, Scientific Directorate, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Renato Mantegazza
- Neuroimmunology and Neuromuscular Diseases, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Pia Bernasconi
- Neuroimmunology and Neuromuscular Diseases, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
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36
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Meyer AP, Roggenbuck J, LoRusso S, Kissel J, Smith RM, Kline D, Arnold WD. Genotype-Phenotype Correlations and Characterization of Medication Use in Inherited Myotonic Disorders. Front Neurol 2020; 11:593. [PMID: 32670189 PMCID: PMC7332828 DOI: 10.3389/fneur.2020.00593] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Accepted: 05/22/2020] [Indexed: 11/13/2022] Open
Abstract
Introduction: Inherited myotonic disorders are genetically heterogeneous and associated with overlapping clinical features of muscle stiffness, weakness, and pain. Data on genotype-phenotype correlations are limited. In this study, clinical features and treatment patterns in genetically characterized myotonic disorders were compared. Methods: A retrospective chart review was completed in patients with genetic variants in CLCN1, SCN4A, DMPK, and CNBP to document clinical signs and symptoms, clinical testing, and antimyotonia medication use. Results: A total of 142 patients (27 CLCN1, 15 SCN4A, 89 DMPK, and 11 CNBP) were reviewed. The frequency of reported symptoms (stiffness, weakness, and pain) and electromyographic spontaneous activity were remarkably similar across genotypes. Most patients were not treated with antimyotonia agents, but those with non-dystrophic disorders were more likely to be on a treatment. Discussion: Among the features reviewed, we did not identify clinical or electrophysiological differences to distinguish CLCN1- and SCN4A-related myotonia. Weakness and pain were more prevalent in non-dystrophic disorders than previously identified. In addition, our results suggest that medical treatments in myotonic disorders may be under-utilized.
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Affiliation(s)
- Alayne P Meyer
- Division of Human Genetics, The Ohio State University, Columbus, OH, United States
| | - Jennifer Roggenbuck
- Division of Human Genetics, The Ohio State University, Columbus, OH, United States
| | - Samantha LoRusso
- Department of Neurology, The Ohio State University, Columbus, OH, United States
| | - John Kissel
- Department of Neurology, The Ohio State University, Columbus, OH, United States
| | - Rachel M Smith
- Department of Biomedical Informatics, Center for Biostatistics, The Ohio State University, Columbus, OH, United States
| | - David Kline
- Department of Biomedical Informatics, Center for Biostatistics, The Ohio State University, Columbus, OH, United States
| | - W David Arnold
- Department of Neurology, The Ohio State University, Columbus, OH, United States
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37
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Molenaar JP, Verhoeven JI, Rodenburg RJ, Kamsteeg EJ, Erasmus CE, Vicart S, Behin A, Bassez G, Magot A, Péréon Y, Brandom BW, Guglielmi V, Vattemi G, Chevessier F, Mathieu J, Franques J, Suetterlin K, Hanna MG, Guyant-Marechal L, Snoeck MM, Roberts ME, Kuntzer T, Fernandez-Torron R, Martínez-Arroyo A, Seeger J, Kusters B, Treves S, van Engelen BG, Eymard B, Voermans NC, Sternberg D. Clinical, morphological and genetic characterization of Brody disease: an international study of 40 patients. Brain 2020; 143:452-466. [PMID: 32040565 PMCID: PMC7009512 DOI: 10.1093/brain/awz410] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 10/30/2019] [Accepted: 11/16/2019] [Indexed: 11/17/2022] Open
Abstract
Brody disease is an autosomal recessive myopathy characterized by exercise-induced muscle stiffness due to mutations in the ATP2A1 gene. Almost 50 years after the initial case presentation, only 18 patients have been reported and many questions regarding the clinical phenotype and results of ancillary investigations remain unanswered, likely leading to incomplete recognition and consequently under-diagnosis. Additionally, little is known about the natural history of the disorder, genotype-phenotype correlations, and the effects of symptomatic treatment. We studied the largest cohort of Brody disease patients to date (n = 40), consisting of 22 new patients (19 novel mutations) and all 18 previously published patients. This observational study shows that the main feature of Brody disease is an exercise-induced muscle stiffness of the limbs, and often of the eyelids. Onset begins in childhood and there was no or only mild progression of symptoms over time. Four patients had episodes resembling malignant hyperthermia. The key finding at physical examination was delayed relaxation after repetitive contractions. Additionally, no atrophy was seen, muscle strength was generally preserved, and some patients had a remarkable athletic build. Symptomatic treatment was mostly ineffective or produced unacceptable side effects. EMG showed silent contractures in approximately half of the patients and no myotonia. Creatine kinase was normal or mildly elevated, and muscle biopsy showed mild myopathic changes with selective type II atrophy. Sarcoplasmic/endoplasmic reticulum Ca2+ ATPase (SERCA) activity was reduced and western blot analysis showed decreased or absent SERCA1 protein. Based on this cohort, we conclude that Brody disease should be considered in cases of exercise-induced muscle stiffness. When physical examination shows delayed relaxation, and there are no myotonic discharges at electromyography, we recommend direct sequencing of the ATP2A1 gene or next generation sequencing with a myopathy panel. Aside from clinical features, SERCA activity measurement and SERCA1 western blot can assist in proving the pathogenicity of novel ATP2A1 mutations. Finally, patients with Brody disease may be at risk for malignant hyperthermia-like episodes, and therefore appropriate perioperative measures are recommended. This study will help improve understanding and recognition of Brody disease as a distinct myopathy in the broader field of calcium-related myopathies.
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Affiliation(s)
- Joery P Molenaar
- Department of Neurology, Donders Centre for Medical Neuroscience, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Jamie I Verhoeven
- Department of Neurology, Donders Centre for Medical Neuroscience, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Richard J Rodenburg
- Department of Pediatrics, Translational Metabolic Laboratory, Radboud Center for Mitochondrial Medicine, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Erik J Kamsteeg
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Corrie E Erasmus
- Department of Neurology, Donders Centre for Medical Neuroscience, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Savine Vicart
- Assistance Publique-Hôpitaux de Paris, Centre de Référence des Canalopathies Musculaires, Centre de Référence des Maladies Neuromusculaires-Paris Est et Service de Génétique, Groupe Hospitalier Pitié-Salpêtrière, Paris, France
| | - Anthony Behin
- Assistance Publique-Hôpitaux de Paris, Centre de Référence des Canalopathies Musculaires, Centre de Référence des Maladies Neuromusculaires-Paris Est et Service de Génétique, Groupe Hospitalier Pitié-Salpêtrière, Paris, France
| | - Guillaume Bassez
- Assistance Publique-Hôpitaux de Paris, Centre de Référence des Canalopathies Musculaires, Centre de Référence des Maladies Neuromusculaires-Paris Est et Service de Génétique, Groupe Hospitalier Pitié-Salpêtrière, Paris, France
| | - Armelle Magot
- CHU Nantes, Centre de Référence Maladies Neuromusculaires AOC, Nantes, France
| | - Yann Péréon
- CHU Nantes, Centre de Référence Maladies Neuromusculaires AOC, Nantes, France
| | - Barbara W Brandom
- Department of Anesthesiology, Children's Hospital, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Valeria Guglielmi
- Department of Neurosciences, Biomedicine and Movement Sciences, Section of Clinical Neurology, University of Verona, Verona, Italy
| | - Gaetano Vattemi
- Department of Neurosciences, Biomedicine and Movement Sciences, Section of Clinical Neurology, University of Verona, Verona, Italy
| | | | - Jean Mathieu
- Neuromuscular Clinic, Centre de Réadaptation en Déficience Physique de Jonquière, Jonquière, Québec, Canada
| | - Jérôme Franques
- Centre de référence des maladies neuromusculaires et de la SLA, hôpital La Timone, AP-HM, Aix-Marseille université, avenue Jean-Moulin, Marseille, France
| | - Karen Suetterlin
- MRC Centre for Neuromuscular Diseases, National Hospital for Neurology and Neurosurgery, Queen Square, London, UK
| | - Michael G Hanna
- MRC Centre for Neuromuscular Diseases, National Hospital for Neurology and Neurosurgery, Queen Square, London, UK
| | | | - Marc M Snoeck
- Department of Anaesthesiology, Canisius-Wilhelmina Ziekenhuis, Nijmegen, The Netherlands
| | - Mark E Roberts
- Department of Neurology, Salford Royal NHS Foundation Trust, Greater Manchester, UK
| | - Thierry Kuntzer
- Nerve-Muscle Unit, Service of Neurology, Department of Clinical Neurosciences, Lausanne University Hospital (CHUV), Lausanne, Switzerland
| | - Roberto Fernandez-Torron
- Neuromuscular Area, Biodonostia Health Research Institute, Department of Neurology, University Hospital Donostia, CIBERNED, San Sebastián, Spain
| | | | - Juergen Seeger
- Sozialpädiatrisches Zentrum Frankfurt Mitte, Neuromuskulares Zentrum, Frankfurt, Germany
| | - Benno Kusters
- Department of Pathology, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Susan Treves
- Departments of Anesthesia and Biomedicine, Basel University and Basel University Hospital, Basel, Switzerland.,Department of Life Sciences, University of Ferrara, Ferrara, Italy
| | - Baziel G van Engelen
- Department of Neurology, Donders Centre for Medical Neuroscience, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Bruno Eymard
- Assistance Publique-Hôpitaux de Paris, Centre de Référence des Canalopathies Musculaires, Centre de Référence des Maladies Neuromusculaires-Paris Est et Service de Génétique, Groupe Hospitalier Pitié-Salpêtrière, Paris, France
| | - Nicol C Voermans
- Department of Neurology, Donders Centre for Medical Neuroscience, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Damien Sternberg
- Assistance Publique-Hôpitaux de Paris, Centre de Référence des Canalopathies Musculaires, Centre de Référence des Maladies Neuromusculaires-Paris Est et Service de Génétique, Groupe Hospitalier Pitié-Salpêtrière, Paris, France
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Mutation spectrum and health status in skeletal muscle channelopathies in Japan. Neuromuscul Disord 2020; 30:546-553. [PMID: 32660787 DOI: 10.1016/j.nmd.2020.06.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Revised: 05/30/2020] [Accepted: 06/02/2020] [Indexed: 11/21/2022]
Abstract
Skeletal muscle channelopathies, including non-dystrophic myotonia and periodic paralysis, are rare hereditary disorders caused by mutations of various ion channel genes. To define the frequency of associated mutations of skeletal muscle channelopathies in Japan, clinical and genetic data of two academic institutions, which provides genetic analysis service, were reviewed. Of 105 unrelated pedigrees genetically confirmed, 66 pedigrees were non-dystrophic myotonias [CLCN1 (n = 30) and SCN4A (n = 36)], 11 were hyperkalemic periodic paralysis (SCN4A), and 28 were hypokalemic periodic paralysis [CACNA1S (n = 16) and SCN4A (n = 12)]. Of the 30 families with myotonia congenita, dominant form (Thomsen type) consisted 67%, and unique mutations, A298T, P480T, T539A, and M560T, not found in Western countries, were commonly identified in CLCN1. Hypokalemic periodic paralysis caused by SCN4A mutations consisted 43% in Japan, which was much higher than previous reports. Furthermore, the quality of life of the patients was assessed using the patient-reported outcome measures, SF-36 and INQoL, for 41 patients. This study indicated that the etiology of skeletal muscle channelopathies in Japan was not identical to previous reports from Western countries, and provided crucial information for genetics as well as future therapeutic interventions.
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Giuliani L, Di Toro A, Urtis M, Smirnova A, Concardi M, Favalli V, Serio A, Grasso M, Arbustini E. Hereditary muscle diseases and the heart: the cardiologist’s perspective. Eur Heart J Suppl 2020; 22:E13-E19. [PMID: 32523431 PMCID: PMC7270924 DOI: 10.1093/eurheartj/suaa051] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- Lorenzo Giuliani
- Centre for Inherited Cardiovascular Diseases, IRCCS Foundation University Hospital Policlinico San Matteo, Pavia, Italy
| | - Alessandro Di Toro
- Centre for Inherited Cardiovascular Diseases, IRCCS Foundation University Hospital Policlinico San Matteo, Pavia, Italy
| | - Mario Urtis
- Centre for Inherited Cardiovascular Diseases, IRCCS Foundation University Hospital Policlinico San Matteo, Pavia, Italy
| | - Alexandra Smirnova
- Centre for Inherited Cardiovascular Diseases, IRCCS Foundation University Hospital Policlinico San Matteo, Pavia, Italy
| | - Monica Concardi
- Centre for Inherited Cardiovascular Diseases, IRCCS Foundation University Hospital Policlinico San Matteo, Pavia, Italy
| | | | - Alessandra Serio
- Centre for Inherited Cardiovascular Diseases, IRCCS Foundation University Hospital Policlinico San Matteo, Pavia, Italy
| | - Maurizia Grasso
- Centre for Inherited Cardiovascular Diseases, IRCCS Foundation University Hospital Policlinico San Matteo, Pavia, Italy
| | - Eloisa Arbustini
- Centre for Inherited Cardiovascular Diseases, IRCCS Foundation University Hospital Policlinico San Matteo, Pavia, Italy
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Comprehensive Exonic Sequencing of Known Ataxia Genes in Episodic Ataxia. Biomedicines 2020; 8:biomedicines8050134. [PMID: 32466254 PMCID: PMC7277596 DOI: 10.3390/biomedicines8050134] [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: 05/04/2020] [Revised: 05/21/2020] [Accepted: 05/21/2020] [Indexed: 01/09/2023] Open
Abstract
Episodic Ataxias (EAs) are a small group (EA1–EA8) of complex neurological conditions that manifest as incidents of poor balance and coordination. Diagnostic testing cannot always find causative variants for the phenotype, however, and this along with the recently proposed EA type 9 (EA9), suggest that more EA genes are yet to be discovered. We previously identified disease-causing mutations in the CACNA1A gene in 48% (n = 15) of 31 patients with a suspected clinical diagnosis of EA2, and referred to our laboratory for CACNA1A gene testing, leaving 52% of these cases (n = 16) with no molecular diagnosis. In this study, whole exome sequencing (WES) was performed on 16 patients who tested negative for CACNA1A mutations. Tiered analysis of WES data was performed to first explore (Tier-1) the ataxia and ataxia-associated genes (n = 170) available in the literature and databases for comprehensive EA molecular genetic testing; we then investigated 353 ion channel genes (Tier-2). Known and potential causal variants were identified in n = 8/16 (50%) patients in 8 genes (SCN2A, p.Val1325Phe; ATP1A3, p.Arg756His; PEX7, p.Tyr40Ter; and KCNA1, p.Arg167Met; CLCN1, p.Gly945ArgfsX39; CACNA1E, p.Ile614Val; SCN1B, p.Cys121Trp; and SCN9A, p.Tyr1217Ter). These results suggest that mutations in these genes might cause an ataxia phenotype or that combinations of more than one mutation contribute to ataxia disorders.
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Modoni A, D'Amico A, Primiano G, Capozzoli F, Desaphy JF, Lo Monaco M. Long-Term Safety and Usefulness of Mexiletine in a Large Cohort of Patients Affected by Non-dystrophic Myotonias. Front Neurol 2020; 11:300. [PMID: 32655465 PMCID: PMC7326038 DOI: 10.3389/fneur.2020.00300] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Accepted: 03/30/2020] [Indexed: 02/01/2023] Open
Abstract
Objective: The aim of our study was to evaluate the long-term efficacy and safety of mexiletine in 112 patients affected by genetically confirmed non-dystrophic myotonias. The study was performed at the Neurophysiologic Division of Fondazione Policlinico Universitario A. Gemelli Istituto di Ricerca e Cura a Carattere Scientifico (IRCCS), Rome and the Children's Hospital Bambino Gesù, Rome. Methods: The treatment was accepted by 59 patients according to clinical severity, individual needs, and concerns about a chronic medication. Forty-three patients were affected by recessive congenita myotonia, 11 by sodium channel myotonia, and five by dominant congenital myotonia. They underwent clinical examination before and after starting therapy, and Electromyography (EMG). A number of recessive myotonia patients underwent a protocol of repetitive nerve stimulations, for detecting and quantifying the transitory weakness, and a modified version of the Timed Up and Go test, to document and quantify the gait impairment. Results: Treatment duration ranged from 1 month to 20 years and the daily dosages in adults ranged between 200 and 600 mg. No patient developed cardiac arrhythmias causing drug discontinuation. Mexiletine was suspended in 13 cases (22%); in three patients, affected by Sodium Channel myotonia, because flecainide showed better efficacy; in one patient because of a gastric cancer antecedent treatment; in four patients because of untreatable dyspepsia; and five patients considered the treatment not necessary. Conclusions: In our experience, mexiletine is very useful and not expensive. We did not observe any hazarding cardiac arrhythmias. Dyspepsia was the most frequent dose-limiting side effect.
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Affiliation(s)
- Anna Modoni
- Department of Geriatric, Neurologic, Orthopedics and Head-Neck Science, Area of Neuroscience, Institute of Neurology, Fondazione Policlinico Universitario A. Gemelli, IRCCS, Rome, Italy
| | - Adele D'Amico
- Unit of Neuromuscular and Neurodegenerative Diseases, Laboratory of Molecular Medicine, Department of Neurosciences, Bambino Gesú Children's Hospital, Rome, Italy
| | - Guido Primiano
- Department of Geriatric, Neurologic, Orthopedics and Head-Neck Science, Area of Neuroscience, Institute of Neurology, Fondazione Policlinico Universitario A. Gemelli, IRCCS, Rome, Italy
| | | | - Jean-François Desaphy
- Department of Biomedical Sciences and Human Oncology, University of Bari Aldo Moro, Polyclinic, Bari, Italy
| | - Mauro Lo Monaco
- Department of Geriatric, Neurologic, Orthopedics and Head-Neck Science, Area of Neuroscience, Institute of Neurology, Fondazione Policlinico Universitario A. Gemelli, IRCCS, Rome, Italy.,MiA Onlus ("Miotonici in Associazione"), Portici, Italy
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Altamura C, Desaphy JF, Conte D, De Luca A, Imbrici P. Skeletal muscle ClC-1 chloride channels in health and diseases. Pflugers Arch 2020; 472:961-975. [PMID: 32361781 DOI: 10.1007/s00424-020-02376-3] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Revised: 03/18/2020] [Accepted: 03/31/2020] [Indexed: 12/14/2022]
Abstract
In 1970, the study of the pathomechanisms underlying myotonia in muscle fibers isolated from myotonic goats highlighted the importance of chloride conductance for skeletal muscle function; 20 years later, the human ClC-1 chloride channel has been cloned; last year, the crystal structure of human protein has been solved. Over the years, the efforts of many researchers led to significant advances in acknowledging the role of ClC-1 in skeletal muscle physiology and the mechanisms through which ClC-1 dysfunctions lead to impaired muscle function. The wide spectrum of pathophysiological conditions associated with modification of ClC-1 activity, either as the primary cause, such as in myotonia congenita, or as a secondary adaptive mechanism in other neuromuscular diseases, supports the idea that ClC-1 is relevant to preserve not only for skeletal muscle excitability, but also for skeletal muscle adaptation to physiological or harmful events. Improving this understanding could open promising avenues toward the development of selective and safe drugs targeting ClC-1, with the aim to restore normal muscle function. This review summarizes the most relevant research on ClC-1 channel physiology, associated diseases, and pharmacology.
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Affiliation(s)
- Concetta Altamura
- Department of Biomedical Sciences and Human Oncology, School of Medicine, University of Bari "Aldo Moro", Bari, Italy
| | - Jean-Francois Desaphy
- Department of Biomedical Sciences and Human Oncology, School of Medicine, University of Bari "Aldo Moro", Bari, Italy
| | - Diana Conte
- Department of Pharmacy-Drug Sciences, University of Bari "Aldo Moro", Bari, Italy
| | - Annamaria De Luca
- Department of Pharmacy-Drug Sciences, University of Bari "Aldo Moro", Bari, Italy
| | - Paola Imbrici
- Department of Pharmacy-Drug Sciences, University of Bari "Aldo Moro", Bari, Italy.
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Sun J, Luo S, Song J, Huang J, Cai S, Zhu W, Zhou L, Xi J, Lin J, Lu J, Xu M, Dou T, Zhao C, Qiao K. Electromyographic Features in a Chinese Cohort With Hereditary Skeletal Muscle Channelopathies. J Clin Neurophysiol 2020; 37:231-238. [DOI: 10.1097/wnp.0000000000000635] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
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Pagliarani S, Lucchiari S, Scarlato M, Redaelli E, Modoni A, Magri F, Fossati B, Previtali SC, Sansone VA, Lecchi M, Lo Monaco M, Meola G, Comi GP. Sodium Channel Myotonia Due to Novel Mutations in Domain I of Na v1.4. Front Neurol 2020; 11:255. [PMID: 32411069 PMCID: PMC7201054 DOI: 10.3389/fneur.2020.00255] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Accepted: 03/17/2020] [Indexed: 11/30/2022] Open
Abstract
Sodium channel myotonia is a form of muscle channelopathy due to mutations that affect the Nav1.4 channel. We describe seven families with a series of symptoms ranging from asymptomatic to clearly myotonic signs that have in common two novel mutations, p.Ile215Thr and p.Gly241Val, in the first domain of the Nav1.4 channel. The families described have been clinically and genetically evaluated. p.Ile215Thr and p.Gly241Val lie, respectively, on extracellular and intracellular loops of the first domain of the Nav1.4 channel. We assessed that the p.Ile215Thr mutation can be related to a founder effect in people from Southern Italy. Electrophysiological evaluation of the channel function showed that the voltage dependence of the activation for both the mutant channels was significantly shifted toward hyperpolarized potentials (Ile215Thr: -28.6 ± 1.5 mV and Gly241Val: -30.2 ± 1.3 mV vs. WT: -18.5 ± 1.3 mV). The slow inactivation was also significantly affected, whereas fast inactivation showed a different behavior in the two mutants. We characterized two novel mutations of the SCN4A gene expanding the knowledge about genetics of mild forms of myotonia, and we present, to our knowledge, the first homozygous patient with sodium channel myotonia.
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Affiliation(s)
- Serena Pagliarani
- Dino Ferrari Center, Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy
| | - Sabrina Lucchiari
- Dino Ferrari Center, Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy
| | - Marina Scarlato
- Department of Neurology and INSPE, IRCCS Ospedale San Raffaele, Milan, Italy
| | - Elisa Redaelli
- Department of Biotechnology and Biosciences, University of Milano - Bicocca, Milan, Italy
| | - Anna Modoni
- Institute of Neurology, Area of Neuroscience, Fondazione Policlinico Universitario A. Gemelli, IRCCS, Rome, Italy
| | - Francesca Magri
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Neurology Unit, Milan, Italy
| | - Barbara Fossati
- Department of Neurorehabilitation Sciences, casa di Cura del Policlinico, Milan, Italy
| | | | - Valeria A. Sansone
- Neurorehabilitation Unit, University of Milan; The NEMO (NEuroMuscular Omniservice) Clinical Center, Milan, Italy
| | - Marzia Lecchi
- Department of Biotechnology and Biosciences and Milan Center for Neuroscience, University of Milano - Bicocca, Milan, Italy
| | - Mauro Lo Monaco
- Institute of Neurology, Area of Neuroscience, Fondazione Policlinico Universitario A. Gemelli, IRCCS, Rome, Italy
- MIA (Myotonics in Association), Portici, Italy
| | - Giovanni Meola
- Department of Neurorehabilitation Sciences, casa di Cura del Policlinico, Milan, Italy
| | - Giacomo P. Comi
- Dino Ferrari Center, Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Neuromuscular and Rare Diseases Unit, Milan, Italy
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Suetterlin KJ, Raja Rayan D, Matthews E, Hanna MG. Mexiletine (NaMuscla) for the treatment of myotonia in non-dystrophic myotonic disorders. Expert Opin Orphan Drugs 2020. [DOI: 10.1080/21678707.2020.1739519] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Affiliation(s)
- Karen J. Suetterlin
- MRC Centre for Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, UK
| | - Dipa Raja Rayan
- MRC Centre for Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, UK
| | - Emma Matthews
- MRC Centre for Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, UK
| | - Michael G Hanna
- MRC Centre for Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, UK
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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: 6] [Impact Index Per Article: 1.5] [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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Morales F, Pusch M. An Up-to-Date Overview of the Complexity of Genotype-Phenotype Relationships in Myotonic Channelopathies. Front Neurol 2020; 10:1404. [PMID: 32010054 PMCID: PMC6978732 DOI: 10.3389/fneur.2019.01404] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Accepted: 12/23/2019] [Indexed: 12/11/2022] Open
Abstract
Myotonic disorders are inherited neuromuscular diseases divided into dystrophic myotonias and non-dystrophic myotonias (NDM). The latter is a group of dominant or recessive diseases caused by mutations in genes encoding ion channels that participate in the generation and control of the skeletal muscle action potential. Their altered function causes hyperexcitability of the muscle membrane, thereby triggering myotonia, the main sign in NDM. Mutations in the genes encoding voltage-gated Cl− and Na+ channels (respectively, CLCN1 and SCN4A) produce a wide spectrum of phenotypes, which differ in age of onset, affected muscles, severity of myotonia, degree of hypertrophy, and muscle weakness, disease progression, among others. More than 200 CLCN1 and 65 SCN4A mutations have been identified and described, but just about half of them have been functionally characterized, an approach that is likely extremely helpful to contribute to improving the so-far rather poor clinical correlations present in NDM. The observed poor correlations may be due to: (1) the wide spectrum of symptoms and overlapping phenotypes present in both groups (Cl− and Na+ myotonic channelopathies) and (2) both genes present high genotypic variability. On the one hand, several mutations cause a unique and reproducible phenotype in most patients. On the other hand, some mutations can have different inheritance pattern and clinical phenotypes in different families. Conversely, different mutations can be translated into very similar phenotypes. For these reasons, the genotype-phenotype relationships in myotonic channelopathies are considered complex. Although the molecular bases for the clinical variability present in myotonic channelopathies remain obscure, several hypotheses have been put forward to explain the variability, which include: (a) differential allelic expression; (b) trans-acting genetic modifiers; (c) epigenetic, hormonal, or environmental factors; and (d) dominance with low penetrance. Improvements in clinical tests, the recognition of the different phenotypes that result from particular mutations and the understanding of how a mutation affects the structure and function of the ion channel, together with genetic screening, is expected to improve clinical correlation in NDMs.
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Affiliation(s)
- Fernando Morales
- Instituto de Investigaciones en Salud, Universidad de Costa, San José, Costa Rica
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Cibulcik F, Spalek P, Martinka I, Zidkova J, Grofik M, Sivak S, Kurca E. Paramyotonia congenita in a Slovak population: Genetic and pedigree analysis of 3 families. Biomed Pap Med Fac Univ Palacky Olomouc Czech Repub 2019; 163:362-365. [DOI: 10.5507/bp.2018.078] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Accepted: 12/09/2018] [Indexed: 11/23/2022] Open
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Barbieri R, Bertelli S, Pusch M, Gavazzo P. Late sodium current blocker GS967 inhibits persistent currents induced by familial hemiplegic migraine type 3 mutations of the SCN1A gene. J Headache Pain 2019; 20:107. [PMID: 31730442 PMCID: PMC6858687 DOI: 10.1186/s10194-019-1056-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Accepted: 10/29/2019] [Indexed: 01/31/2023] Open
Abstract
Background Familial hemiplegic migraine (FHM) is a group of genetic migraine, associated with hemiparesis and aura. Three causative different genes have been identified, all of which are involved in membrane ion transport. Among these, SCN1A encodes the voltage-gated Na+ channel Nav1.1, and FHM caused by mutations of SCN1A is named FHM3. For 7 of the 12 known FHM3-causing SCNA1 mutations functional consequences have been investigated, and even if gain of function effect seems to be a predominant phenotype, for several mutations conflicting results have been obtained and the available data do not reveal a univocal FHM3 pathomechanism. Methods To obtain a more complete picture, here, we characterized by patch clamp approach the remaining 5 mutations (Q1489H, I1498M, F1499 L, M1500 V, F1661 L) in heterologous expression systems. Results With the exception of I1498M, all mutants exhibited the same current density as WT and exhibited a shift of the steady state inactivation to more positive voltages, an accelerated recovery from inactivation, and an increase of the persistent current, revealing that most FHM3 mutations induce a gain of function. We also determined the effect of GS967, a late Na+ current blocker, on the above mentioned mutants as well as on previously characterized ones (L1649Q, L1670 W, F1774S). GS967 inhibited persistent currents of all SCNA1 FMH3-related mutants and dramatically slowed the recovery from fast inactivation of WT and mutants, consistent with the hypothesis that GS967 specifically binds to and thereby stabilizes the fast inactivated state. Simulation of neuronal firing showed that enhanced persistent currents cause an increase of ionic fluxes during action potential repolarization and consequent accumulation of K+ and/or exhaustion of neuronal energy resources. In silico application of GS967 largely reduced net ionic currents in neurons without impairing excitability. Conclusion In conclusion, late Na+ current blockers appear a promising specific pharmacological treatment of FHM3.
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Affiliation(s)
- R Barbieri
- Biophysics Institute, National Research Council, Via De Marini 6, Genoa, Italy
| | - S Bertelli
- Biophysics Institute, National Research Council, Via De Marini 6, Genoa, Italy.,International School of Advanced Studies (SISSA), Via Bonomea, 265, Trieste, Italy
| | - M Pusch
- Biophysics Institute, National Research Council, Via De Marini 6, Genoa, Italy
| | - P Gavazzo
- Biophysics Institute, National Research Council, Via De Marini 6, Genoa, Italy.
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Stee K, Van Poucke M, Peelman L, Lowrie M. Paradoxical pseudomyotonia in English Springer and Cocker Spaniels. J Vet Intern Med 2019; 34:253-257. [PMID: 31729100 PMCID: PMC6979413 DOI: 10.1111/jvim.15660] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Accepted: 10/28/2019] [Indexed: 12/30/2022] Open
Abstract
Background Paramyotonia congenita and Brody disease are well‐described conditions in humans, characterized by exercise‐induced myotonic‐like muscle stiffness. A syndrome similar to Brody disease has been reported in cattle. Reports of a similar syndrome in dogs are scarce. Objectives To define and describe the clinical, diagnostic, and genetic features and disease course of paradoxical pseudomyotonia in Spaniel dogs. Animals Seven client‐owned dogs (4 English Springer Spaniels and 3 English Cocker Spaniels) with clinically confirmed episodes of exercise‐induced generalized myotonic‐like muscle stiffness. Methods Sequential case study. Results All dogs were <24 months of age at onset. The episodes of myotonic‐like generalized muscle stiffness always occurred with exercise, and spontaneously resolved with rest in <45 seconds in all but 1 dog. Extreme outside temperatures seemed to considerably worsen episode frequency and severity in most dogs. Complete blood count, serum biochemistry including electrolytes, urinalysis, brain magnetic resonance imaging, cerebrospinal fluid analysis, electromyography, motor nerve conduction velocity, ECG, and echocardiography were unremarkable. Muscle biopsy samples showed moderate but nonspecific muscle atrophy. The episodes seemed to remain stable or decrease in severity and frequency in 6/7 dogs, and often could be decreased or prevented by avoiding the episode triggers. The underlying genetic cause is not identified yet, because no disease‐causing variants could be found in the coding sequence or splice sites of the 2 major candidate genes, SCN4A and ATP2A1. Conclusions and Clinical Importance Paradoxical pseudomyotonia is a disease affecting Spaniels. It is of variable severity but benign in most cases.
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Affiliation(s)
| | - Mario Van Poucke
- Department of Nutrition, Genetics and Ethology, Ghent University, Merelbeke, Belgium
| | - Luc Peelman
- Department of Nutrition, Genetics and Ethology, Ghent University, Merelbeke, Belgium
| | - Mark Lowrie
- Dovecote Veterinary Hospital, Derby, United Kingdom
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