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Elaraby NM, Ahmed HA, Dawoud H, Ashaat NA, Azmy A, Galal ER, Elhusseny Y, Awady HE, Metwally AM, Ashaat EA. Clinical and molecular characterization of myotonia congenita using whole-exome sequencing in Egyptian patients. Mol Biol Rep 2024; 51:766. [PMID: 38877370 DOI: 10.1007/s11033-024-09646-8] [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: 03/28/2024] [Accepted: 05/16/2024] [Indexed: 06/16/2024]
Abstract
BACKGROUND Myotonia Congenita (MC) is a rare disease classified into two major forms; Thomsen and Becker disease caused by mutations in the CLCN1 gene, which affects muscle excitability and encodes voltage-gated chloride channels (CLC-1). While, there are no data regarding the clinical and molecular characterization of myotonia in Egyptian patients. METHODS Herein, we report seven Egyptian MC patients from six unrelated families. Following the clinical diagnosis, whole-exome sequencing (WES) was performed for genetic diagnosis. Various in silico prediction tools were utilized to interpret variant pathogenicity. The candidate variants were then validated using Sanger sequencing technique. RESULTS In total, seven cases were recruited. The ages at the examination were ranged from eight months to nineteen years. Clinical manifestations included warm-up phenomenon, hand grip, and percussion myotonia. Electromyography was performed in all patients and revealed myotonic discharges. Molecular genetic analysis revealed five different variants. Of them, we identified two novel variants in the CLCN1 gene ( c.1583G > C; p.Gly528Ala and c.2203_2216del;p.Thr735ValfsTer57) and three known variants in the CLCN1 and SCN4A gene. According to in silico tools, the identified novel variants were predicted to have deleterious effects. CONCLUSIONS As the first study to apply WES among Egyptian MC patients, our findings reported two novel heterozygous variants that expand the CLCN1 mutational spectrum for MC diagnosis. These results further confirm that genetic testing is essential for early diagnosis of MC, which affects follow-up treatment and prognostic assessment in clinical practice.
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Affiliation(s)
- Nesma M Elaraby
- Medical Molecular Genetics Department, Human Genetics and Genome Research Institute, National Research Centre, Dokki, Cairo, Egypt.
| | - Hoda A Ahmed
- Medical Molecular Genetics Department, Human Genetics and Genome Research Institute, National Research Centre, Dokki, Cairo, Egypt
| | - Heba Dawoud
- Pediatric Department, Tanta University, Gharbia, Egypt
| | - Neveen A Ashaat
- Professor of Human Genetics, Ain Shams University, Cairo, Egypt
| | - Ashraf Azmy
- Child Health Department, Medical Research and Clinical Studies Institute, National Research Centre, Dokki, Cairo, Egypt
| | - Eman Reda Galal
- Biochemistry and Molecular Biology Department, Faculty of Pharmacy (Girls), Al-Azhar University, Cairo, Egypt
| | - Yasmine Elhusseny
- Lecturer of Medical Biochemistry and Molecular Biology, School of Medicine, Newgiza University, Giza, Egypt
| | - Heba El Awady
- Pediatric Department, Fayoum University Hospitals, Fayoum, Egypt
| | - Ammal M Metwally
- Community Medicine Research Department/Medical Research, Clinical Studies Institute/National Research Centre (Affiliation ID: 60014618), Dokki, Cairo, Egypt
| | - Engy A Ashaat
- Clinical Genetics Department, Human Genetics and Genome Research Institute, National Research Centre, Cairo, Egypt
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Olave-Rodriguez JA, Bonilla-Escobar FJ, Candelo E, Rodriguez-Rojas LX. First Two Case Reports of Becker's Type Myotonia Congenita in Colombia: Clinical and Genetic Features. Appl Clin Genet 2021; 14:473-479. [PMID: 34938096 PMCID: PMC8687676 DOI: 10.2147/tacg.s323559] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2021] [Accepted: 10/26/2021] [Indexed: 11/23/2022] Open
Abstract
Background Becker's type myotonia congenita is an autosomal recessive nondystrophic skeletal muscle disorder characterized by muscle stiffness and the inability of muscle relaxation after voluntary contraction. It is caused by mutations in the CLCN1 gene, which encodes for a chloride channel mainly expressed in the striated muscle. Most cases have been reported in the European population, and only mexiletine has demonstrated a randomized placebo-controlled, double-blinded effectiveness. Case Presentation We present two male siblings from Colombia with Latino ancestry, without parental consanguinity, with myotonia during voluntary movements, muscle hypertrophy of lower extremities, transient weakness, and severe muscle fatigue after exercise from three years of age. A genetic panel for dystrophic muscle disorders and a muscle biopsy were both negative. Genetic testing was performed in their second decade of life. Both patients' exomic sequencing test reported the mutation c.1129C >T (p.Arg377*) affecting exon 10 of the CLCN1, generating a premature stop codon. This mutation was described as pathogenic and observed in only one other patient in the United Kingdom. Conclusion To our knowledge, these are the first cases of Becker's type myotonia congenita reported in Colombia. Increasing awareness of healthcare providers for this type of disease in the region could lead to the identification of undiagnosed patients. Limited availability of medical geneticists as well as genetic testing may be the cause of the lack of previous description of cases, in addition to the delay in the diagnosis of the patients. Further epidemiological studies can reveal underdiagnosed myotonias in the country and in the Latin-American region.
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Affiliation(s)
| | - Francisco Javier Bonilla-Escobar
- Somos Ciencia al Servicio de la Comunidad, Fundación SCISCO/Science to Serve the Community, SCISCO Foundation, Cali, Colombia.,Universidad del Valle, Cali, Colombia.,Institute for Clinical Research Education, University of Pittsburgh, Pittsburgh, PA, USA
| | - Estephania Candelo
- Centro de Investigaciones Clínicas, Fundación Valle del Lili, Cali, Colombia.,Centro enfermedades raras y malformaciones congenitas (CIACER), Universidad Icesi, Cali, Colombia
| | - Lisa Ximena Rodriguez-Rojas
- Universidad Icesi, Faculty of Health Sciences, Cali, Colombia.,Human Genetics Department, Fundación Valle del Lili, Cali, Colombia
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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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Sparber P, Sharova M, Filatova A, Shchagina O, Ivanova E, Dadali E, Skoblov M. Recessive myotonia congenita caused by a homozygous splice site variant in CLCN1 gene: a case report. BMC MEDICAL GENETICS 2020; 21:197. [PMID: 33092578 PMCID: PMC7579786 DOI: 10.1186/s12881-020-01128-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Accepted: 09/22/2020] [Indexed: 02/01/2023]
Abstract
Background Myotonia congenita is a rare neuromuscular disease, which is characterized by a delay in muscle relaxation after evoked or voluntary contraction. Myotonia congenita can be inherited in a dominant (Thomsen disease) and recessive form (Becker disease) and both are caused by pathogenic variants in the CLCN1 gene. Noncanonical splice site variants are often classified as variants of uncertain significance, due to insufficient accuracy of splice-predicting tools. Functional analysis using minigene plasmids is widely used in such cases. Moreover, functional analysis is very useful in investigation of the disease pathogenesis, which is necessary for development of future therapeutic approaches. To our knowledge only one noncanonical splice site variant in the CLCN1 gene was functionally characterized to date. We further contribute to this field by evaluation the molecular mechanism of splicing alteration caused by the c.1582 + 5G > A in a homozygous state. Case presentation We report a clinical case of an affected 6-y.o boy with athletic appearance due to muscle hypertrophy, calf muscle stiffness, cramping and various myotonic signs in a consanguineous family with no history of neuromuscular disorders. The neurological examination showed percussion-activated myotonia in the hands and legs. Plasma creatine kinase enzyme and transaminases levels were normal. Electromyography at the time of examination shows myotonic runs in the upper and lower extremities. Conclusions Functional analysis of the variant in a minigene system showed alteration of splicing leading to loss of function, thereby confirming that the variant is pathogenic.
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Affiliation(s)
- Peter Sparber
- Research Centre for Medical Genetics Moskvorechie 1, Moscow, 115522, Russia.
| | - Margarita Sharova
- Research Centre for Medical Genetics Moskvorechie 1, Moscow, 115522, Russia
| | - Alexandra Filatova
- Research Centre for Medical Genetics Moskvorechie 1, Moscow, 115522, Russia
| | - Olga Shchagina
- Research Centre for Medical Genetics Moskvorechie 1, Moscow, 115522, Russia
| | - Evgeniya Ivanova
- Research Centre for Medical Genetics Moskvorechie 1, Moscow, 115522, Russia
| | - Elena Dadali
- Research Centre for Medical Genetics Moskvorechie 1, Moscow, 115522, Russia
| | - Mikhail Skoblov
- Research Centre for Medical Genetics Moskvorechie 1, Moscow, 115522, Russia
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