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Seifert BA, Reddi HV, Kang BE, Bean LJH, Shealy A, Rose NC. Myotonic dystrophy type 1 testing, 2024 revision: A technical standard of the American College of Medical Genetics and Genomics (ACMG). Genet Med 2024:101145. [PMID: 38836869 DOI: 10.1016/j.gim.2024.101145] [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: 04/11/2024] [Accepted: 04/11/2024] [Indexed: 06/06/2024] Open
Abstract
Myotonic dystrophy type 1 (DM1) is a form of muscular dystrophy causing progressive muscle loss and weakness. Although clinical features can manifest at any age, it is the most common form of muscular dystrophy with onset in adulthood. DM1 is an autosomal dominant condition, resulting from an unstable CTG expansion in the 3'-untranslated region of the myotonic dystrophy protein kinase (DMPK) gene. The age of onset and the severity of the phenotype are roughly correlated with the size of the CTG expansion. Multiple methodologies can be used to diagnose affected individuals with DM1, including polymerase chain reaction, Southern blot, and triplet repeat-primed polymerase chain reaction. Recently, triplet repeat interruptions have been described, which may affect clinical outcomes of a fully-variable allele in DMPK. This document supersedes the Technical Standards and Guidelines for Myotonic Dystrophy originally published in 2009 and reaffirmed in 2015. It is designed for genetic testing professionals who are already familiar with the disease and the methods of analysis.
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Affiliation(s)
- Bryce A Seifert
- National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD
| | - Honey V Reddi
- Department of Pathology and Laboratory Medicine, Medical College of Wisconsin, Milwaukee, WI
| | - Benjamin E Kang
- Department of Pathology and Pediatrics, University of Michigan Medical School, Ann Arbor, MI; Vanderbilt University Medical Center, Nashville, TN
| | | | - Amy Shealy
- Cleveland Clinic Center for Personalized Genetic Healthcare, Cleveland, OH
| | - Nancy C Rose
- Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, University of Utah, Salt Lake City, UT
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2
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Ostojić S, Kovačević G, Meola G, Pešović J, Savić-Pavićević D, Brkušanin M, Kravljanac R, Perić M, Martić J, Pejić K, Ristić S, Perić S. Main features and disease outcome of congenital myotonic dystrophy - experience from a single tertiary center. Neuromuscul Disord 2024; 40:16-23. [PMID: 38810326 DOI: 10.1016/j.nmd.2024.05.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2024] [Revised: 04/05/2024] [Accepted: 05/08/2024] [Indexed: 05/31/2024]
Abstract
Congenital myotonic dystrophy type 1 (CDM1) is a rare neuromuscular disease. The aim of our study was to evaluate clinical variability of CDM1 and factors that may influence survival in CDM1. Research included 24 pediatric patients with CDM1. Most of our patients had some form of hypoxic ischemic encephalopathy (HIE) (74 %), from mild to severe. Prolonged and complicated deliveries (75 %), high percentage of children resuscitated at birth (57 %) and respiratory insufficiency (46 %) with consequent hypoxia were the main reasons that could explain high percentage of HIE. Therapeutic hypothermia was applied in three children with poor outcome. Median survival of all CDM1 was 14.2 ± 1.5 years. Six patients had a fatal outcome (25 %). Their mean age of death was 3.0 ± 2.8 years. Poor prognostic factors for the survival of our CDM1 patients were: preterm delivery, resuscitation at birth, severe HIE, hypothermia treatment and permanent mechanical ventilation. Respiratory insufficiency was the main life-threatening factor. Our data clearly indicates the need to develop natural history studies in CDM1 in order to enhance the standards of care and to develop clinical trials investigating causative therapies in pediatric patients with CDM1.
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Affiliation(s)
- Slavica Ostojić
- Neurology Department, Institute for Mother and Child Health Care of Serbia "Dr. Vukan Cupic", Faculty of Medicine, University of Belgrade, Serbia.
| | - Gordana Kovačević
- Neurology Department, Institute for Mother and Child Health Care of Serbia "Dr. Vukan Cupic", Faculty of Medicine, University of Belgrade, Serbia
| | - Giovanni Meola
- Department of Neurorehabilitation Sciences, Casa Di Cura Igea, Department of Biomedical Sciences for Health, University of Milan, Fondazione Malattie Miotoniche-FMM, Milan Italy
| | - Jovan Pešović
- University of Belgrade-Faculty of Biology, Center for Human Molecular Genetics, Belgrade, Serbia
| | - Dušanka Savić-Pavićević
- University of Belgrade-Faculty of Biology, Center for Human Molecular Genetics, Belgrade, Serbia
| | - Miloš Brkušanin
- University of Belgrade-Faculty of Biology, Center for Human Molecular Genetics, Belgrade, Serbia
| | - Ružica Kravljanac
- Neurology Department, Institute for Mother and Child Health Care of Serbia "Dr. Vukan Cupic", Faculty of Medicine, University of Belgrade, Serbia
| | - Marina Perić
- Nephrology Department, Institute for Mother and Child Health Care of Serbia "Dr. Vukan Cupic", Faculty of Medicine, University of Belgrade, Serbia
| | - Jelena Martić
- Intensive Care Unit, Institute for Mother and Child Health Care of Serbia "Dr. Vukan Cupic", Faculty of Medicine, University of Belgrade, Serbia
| | - Katarina Pejić
- Intensive Care Unit, Institute for Mother and Child Health Care of Serbia "Dr. Vukan Cupic", Faculty of Medicine, University of Belgrade, Serbia
| | - Snežana Ristić
- Intensive Care Unit, Institute for Mother and Child Health Care of Serbia "Dr. Vukan Cupic", Faculty of Medicine, University of Belgrade, Serbia
| | - Stojan Perić
- Neurology Clinic, University Clinical Center of Serbia, Faculty of Medicine, University of Belgrade, Serbia
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3
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Livshits G, Kalinkovich A. Restoration of epigenetic impairment in the skeletal muscle and chronic inflammation resolution as a therapeutic approach in sarcopenia. Ageing Res Rev 2024; 96:102267. [PMID: 38462046 DOI: 10.1016/j.arr.2024.102267] [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: 11/20/2023] [Revised: 02/17/2024] [Accepted: 03/06/2024] [Indexed: 03/12/2024]
Abstract
Sarcopenia is an age-associated loss of skeletal muscle mass, strength, and function, accompanied by severe adverse health outcomes, such as falls and fractures, functional decline, high health costs, and mortality. Hence, its prevention and treatment have become increasingly urgent. However, despite the wide prevalence and extensive research on sarcopenia, no FDA-approved disease-modifying drugs exist. This is probably due to a poor understanding of the mechanisms underlying its pathophysiology. Recent evidence demonstrate that sarcopenia development is characterized by two key elements: (i) epigenetic dysregulation of multiple molecular pathways associated with sarcopenia pathogenesis, such as protein remodeling, insulin resistance, mitochondria impairments, and (ii) the creation of a systemic, chronic, low-grade inflammation (SCLGI). In this review, we focus on the epigenetic regulators that have been implicated in skeletal muscle deterioration, their individual roles, and possible crosstalk. We also discuss epidrugs, which are the pharmaceuticals with the potential to restore the epigenetic mechanisms deregulated in sarcopenia. In addition, we discuss the mechanisms underlying failed SCLGI resolution in sarcopenia and the potential application of pro-resolving molecules, comprising specialized pro-resolving mediators (SPMs) and their stable mimetics and receptor agonists. These compounds, as well as epidrugs, reveal beneficial effects in preclinical studies related to sarcopenia. Based on these encouraging observations, we propose the combination of epidrugs with SCLI-resolving agents as a new therapeutic approach for sarcopenia that can effectively attenuate of its manifestations.
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Affiliation(s)
- Gregory Livshits
- Department of Morphological Sciences, Adelson School of Medicine, Ariel University, Ariel 4077625, Israel; Department of Anatomy and Anthropology, Faculty of Medical and Health Sciences, School of Medicine, Tel-Aviv University, Tel-Aviv 6905126, Israel.
| | - Alexander Kalinkovich
- Department of Anatomy and Anthropology, Faculty of Medical and Health Sciences, School of Medicine, Tel-Aviv University, Tel-Aviv 6905126, Israel
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Rajan-Babu IS, Dolzhenko E, Eberle MA, Friedman JM. Sequence composition changes in short tandem repeats: heterogeneity, detection, mechanisms and clinical implications. Nat Rev Genet 2024:10.1038/s41576-024-00696-z. [PMID: 38467784 DOI: 10.1038/s41576-024-00696-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/19/2024] [Indexed: 03/13/2024]
Abstract
Short tandem repeats (STRs) are a class of repetitive elements, composed of tandem arrays of 1-6 base pair sequence motifs, that comprise a substantial fraction of the human genome. STR expansions can cause a wide range of neurological and neuromuscular conditions, known as repeat expansion disorders, whose age of onset, severity, penetrance and/or clinical phenotype are influenced by the length of the repeats and their sequence composition. The presence of non-canonical motifs, depending on the type, frequency and position within the repeat tract, can alter clinical outcomes by modifying somatic and intergenerational repeat stability, gene expression and mutant transcript-mediated and/or protein-mediated toxicities. Here, we review the diverse structural conformations of repeat expansions, technological advances for the characterization of changes in sequence composition, their clinical correlations and the impact on disease mechanisms.
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Affiliation(s)
- Indhu-Shree Rajan-Babu
- Department of Medical Genetics, The University of British Columbia, and Children's & Women's Hospital, Vancouver, British Columbia, Canada.
| | | | | | - Jan M Friedman
- Department of Medical Genetics, The University of British Columbia, and Children's & Women's Hospital, Vancouver, British Columbia, Canada
- BC Children's Hospital Research Institute, Vancouver, British Columbia, Canada
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5
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Cascais I, Garrido C, Morais L, Amorim R, Lima R, Mansilha HF, Correia T, Oliveira A, Santos M. Myotonic dystrophy type 1 (Steinert disease): 29 years of experience at a tertiary pediatric hospital. Eur J Paediatr Neurol 2024; 48:85-90. [PMID: 38088012 DOI: 10.1016/j.ejpn.2023.12.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Revised: 11/19/2023] [Accepted: 12/03/2023] [Indexed: 03/23/2024]
Abstract
BACKGROUND Myotonic dystrophy type 1 (DM1) is a multisystemic disorder caused by the expansion of a noncoding triplet repeat. METHODS A cross-sectional study was performed to characterize pediatric patients with DM1 followed in a tertiary hospital over the last 29 years, comparing the congenital and the childhood/juvenile-onset forms. RESULTS Thirty-seven patients (59.5 % male) were included, with a median age at the latest assessment of 16.8 years and a median follow-up of 7.7 years. Eleven patients were lost to follow-up, and two died. Twenty-five had congenital DM1 (CDM1), and this form had significantly higher triplet repeat length, history of polyhydramnios, lower median age at diagnosis, and first and last assessment. Common symptoms included distal skeletal muscle weakness (75.7 %) and facial involvement (94.6 %), along with dysphonia/dysarthria (73.0 %) and myotonia (73.0 %). Delayed independent ambulation frequency was significantly higher for CDM1 cases. Skeletal deformities affected 54.1 %, with talipes equinovarus and scoliosis occurring exclusively in CDM1 patients. Cognitive deficit was present in 75.7 % of cases. Polysomnograms revealed seven cases of obstructive sleep apnea and two of hypoventilation. Noninvasive ventilation was used in nine cases, and three had recurrent respiratory infections. The cardiovascular system was affected in 21.6 % of cases. Gastrointestinal issues included constipation (24.3 %), feeding difficulties (16.2 %), and cholelithiasis (5.4 %). Cataracts, epilepsy, and diabetes mellitus were reported in two cases each. CONCLUSION Our study highlights the diverse spectrum of severity and multiorgan involvement of DM1 in pediatric patients. It underscores the importance of establishing a pediatric-specific standard of care to enhance health outcomes through comprehensive multidisciplinary management.
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Affiliation(s)
- Inês Cascais
- Department of Pediatrics, Centro Materno Infantil Do Norte (CMIN), Centro Hospitalar Universitário de Santo António (CHUdSA), Porto, Portugal.
| | - Cristina Garrido
- Multidisciplinary Pediatric Neuromuscular Diseases Team, CMIN, CHUdSA, European Reference Network for Rare Neuromuscular Diseases (EURO-NMD) Center, Porto, Portugal
| | - Lurdes Morais
- Multidisciplinary Pediatric Neuromuscular Diseases Team, CMIN, CHUdSA, European Reference Network for Rare Neuromuscular Diseases (EURO-NMD) Center, Porto, Portugal
| | - Rosa Amorim
- Multidisciplinary Pediatric Neuromuscular Diseases Team, CMIN, CHUdSA, European Reference Network for Rare Neuromuscular Diseases (EURO-NMD) Center, Porto, Portugal
| | - Rosa Lima
- Multidisciplinary Pediatric Neuromuscular Diseases Team, CMIN, CHUdSA, European Reference Network for Rare Neuromuscular Diseases (EURO-NMD) Center, Porto, Portugal
| | - Helena Ferreira Mansilha
- Multidisciplinary Pediatric Neuromuscular Diseases Team, CMIN, CHUdSA, European Reference Network for Rare Neuromuscular Diseases (EURO-NMD) Center, Porto, Portugal
| | - Teresa Correia
- Multidisciplinary Pediatric Neuromuscular Diseases Team, CMIN, CHUdSA, European Reference Network for Rare Neuromuscular Diseases (EURO-NMD) Center, Porto, Portugal
| | - António Oliveira
- Multidisciplinary Pediatric Neuromuscular Diseases Team, CMIN, CHUdSA, European Reference Network for Rare Neuromuscular Diseases (EURO-NMD) Center, Porto, Portugal
| | - Manuela Santos
- Multidisciplinary Pediatric Neuromuscular Diseases Team, CMIN, CHUdSA, European Reference Network for Rare Neuromuscular Diseases (EURO-NMD) Center, Porto, Portugal
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Visconti VV, Macrì E, D'Apice MR, Centofanti F, Massa R, Novelli G, Botta A. In Cis Effect of DMPK Expanded Alleles in Myotonic Dystrophy Type 1 Patients Carrying Variant Repeats at 5' and 3' Ends of the CTG Array. Int J Mol Sci 2023; 24:10129. [PMID: 37373276 DOI: 10.3390/ijms241210129] [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: 04/17/2023] [Revised: 06/07/2023] [Accepted: 06/12/2023] [Indexed: 06/29/2023] Open
Abstract
Myotonic dystrophy type 1 (DM1) is an autosomal dominant multisystemic disease caused by a CTG repeat expansion in the 3'-untranslated region (UTR) of DMPK gene. DM1 alleles containing non-CTG variant repeats (VRs) have been described, with uncertain molecular and clinical consequences. The expanded trinucleotide array is flanked by two CpG islands, and the presence of VRs could confer an additional level of epigenetic variability. This study aims to investigate the association between VR-containing DMPK alleles, parental inheritance and methylation pattern of the DM1 locus. The DM1 mutation has been characterized in 20 patients using a combination of SR-PCR, TP-PCR, modified TP-PCR and LR-PCR. Non-CTG motifs have been confirmed by Sanger sequencing. The methylation pattern of the DM1 locus was determined by bisulfite pyrosequencing. We characterized 7 patients with VRs within the CTG tract at 5' end and 13 patients carrying non-CTG sequences at 3' end of the DM1 expansion. DMPK alleles with VRs at 5' end or 3' end were invariably unmethylated upstream of the CTG expansion. Interestingly, DM1 patients with VRs at the 3' end showed higher methylation levels in the downstream island of the CTG repeat tract, preferentially when the disease allele was maternally inherited. Our results suggest a potential correlation between VRs, parental origin of the mutation and methylation pattern of the DMPK expanded alleles. A differential CpG methylation status could play a role in the phenotypic variability of DM1 patients, representing a potentially useful diagnostic tool.
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Affiliation(s)
- Virginia Veronica Visconti
- Department of Biomedicine and Prevention, Genetics Unit, University of Rome "Tor Vergata", Via Montpellier 1, 00133 Rome, Italy
| | - Elisa Macrì
- Department of Biomedicine and Prevention, Genetics Unit, University of Rome "Tor Vergata", Via Montpellier 1, 00133 Rome, Italy
| | - Maria Rosaria D'Apice
- Laboratory of Medical Genetics, Tor Vergata Hospital, Viale Oxford 81, 00133 Rome, Italy
| | - Federica Centofanti
- Department of Biomedicine and Prevention, Genetics Unit, University of Rome "Tor Vergata", Via Montpellier 1, 00133 Rome, Italy
| | - Roberto Massa
- Department of Systems Medicine, University of Rome "Tor Vergata", Via Montpellier 1, 00133 Rome, Italy
| | - Giuseppe Novelli
- Department of Biomedicine and Prevention, Genetics Unit, University of Rome "Tor Vergata", Via Montpellier 1, 00133 Rome, Italy
- Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Neuromed, Via Atinense 18, 86077 Pozzilli, Italy
- Department of Pharmacology, School of Medicine, University of Nevada, Reno, NV 89557, USA
| | - Annalisa Botta
- Department of Biomedicine and Prevention, Genetics Unit, University of Rome "Tor Vergata", Via Montpellier 1, 00133 Rome, Italy
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7
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Rapid and comprehensive diagnostic method for repeat expansion diseases using nanopore sequencing. NPJ Genom Med 2022; 7:62. [PMID: 36289212 PMCID: PMC9606279 DOI: 10.1038/s41525-022-00331-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Accepted: 09/30/2022] [Indexed: 11/23/2022] Open
Abstract
We developed a diagnostic method for repeat expansion diseases using a long-read sequencer to improve currently available, low throughput diagnostic methods. We employed the real-time target enrichment system of the nanopore GridION sequencer using the adaptive sampling option, in which software-based target assignment is available without prior sample enrichment, and built an analysis pipeline that prioritized the disease-causing loci. Twenty-two patients with various neurological and neuromuscular diseases, including 12 with genetically diagnosed repeat expansion diseases and 10 manifesting cerebellar ataxia, but without genetic diagnosis, were analyzed. We first sequenced the 12 molecularly diagnosed patients and accurately confirmed expanded repeats in all with uniform depth of coverage across the loci. Next, we applied our method and a conventional method to 10 molecularly undiagnosed patients. Our method corrected inaccurate diagnoses of two patients by the conventional method. Our method is superior to conventional diagnostic methods in terms of speed, accuracy, and comprehensiveness.
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8
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Timchenko L. Myotonic Dystrophy: From Molecular Pathogenesis to Therapeutics. Int J Mol Sci 2022; 23:ijms231911954. [PMID: 36233257 PMCID: PMC9570427 DOI: 10.3390/ijms231911954] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Accepted: 09/06/2022] [Indexed: 11/16/2022] Open
Affiliation(s)
- Lubov Timchenko
- Departments of Neurology and Pediatrics, Cincinnati Children's Hospital Medical Center and the University of Cincinnati, Cincinnati, OH 45229, USA
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9
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Scutifero M, Lanza M, Petillo R, De Bernardo M, Passamano L, Rosa N, Politano L. Gender effect on onset, prevalence and surgical treatment of cataract in patients with Myotonic Dystrophy type 1. ACTA MYOLOGICA : MYOPATHIES AND CARDIOMYOPATHIES : OFFICIAL JOURNAL OF THE MEDITERRANEAN SOCIETY OF MYOLOGY 2022; 41:105-110. [PMID: 36349183 PMCID: PMC9628803 DOI: 10.36185/2532-1900-n75] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Accepted: 09/21/2022] [Indexed: 11/21/2022]
Abstract
Myotonic Dystrophy type 1 (DM1) is the most common muscular dystrophy in adults, affecting 1:8000 individuals. It is a multi-systemic disorder involving muscle, heart, endocrine and respiratory apparatus and eye. The eye symptoms can include ptosis, external ophthalmoplegia, epiphora, and early onset cataracts. Cataracts occur at a much earlier age (usually between 30 and 40) than the general population, where females are usually affected more than men. We studied gender differences in cataract prevalence and treatment age in 243 DM1 patients (134 M; 109 F), aged 18 to 70 years, who were subsequently screened at routine follow-up. For each patient, information was collected on age, sex, CTG expansion, age of cataract onset, and age at cataract surgery, when available. Seventy-three patients, 30 females and 43 males, had cataracts, at a mean age of onset of 41.14 ± 12.64 in females, and 40.36 ± 10.03 in males. Sixty-nine of them underwent cataract surgery, males at an earlier age than females (42.8 ± 9.8 years versus 47.3 ± 12.6 years) and in 52.5% of cases before the age of 40, compared to 17.2% of females. The difference was statistically significant. The assumption that females in general and those with DM1 in particular develop cataracts more frequently and earlier than males is not confirmed, at least in this study. A possible explanation for these results could be related to non-advanced age, the protective role of estrogen and the lower prevalence of smoking in the study population.
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Affiliation(s)
- Marianna Scutifero
- Cardiomyology and Medical Genetics,
University Hospital of Campania “Luigi
Vanvitelli”, Naples, Italy
| | - Michele Lanza
- Eye Department, University of Campania
“Luigi Vanvitelli”, Naples,
Italy
| | - Roberta Petillo
- Cardiomyology and Medical Genetics,
University Hospital of Campania “Luigi
Vanvitelli”, Naples, Italy
| | | | - Luigia Passamano
- Cardiomyology and Medical Genetics,
University Hospital of Campania “Luigi
Vanvitelli”, Naples, Italy
| | - Nicola Rosa
- Department of Medicine and Surgery,
University of Salerno, Salerno,
Italy
| | - Luisa Politano
- Cardiomyology and Medical Genetics,
University Hospital of Campania “Luigi
Vanvitelli”, Naples, Italy,Correspondence Luisa Politano Cardiomyology and
Medical Genetics, University Hospital of Campania “Luigi
Vanvitelli”, piazza Miraglia 2, 80138 Naples, Italy. E-mail:
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10
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Identification of a CCG-Enriched Expanded Allele in Patients with Myotonic Dystrophy Type 1 Using Amplification-Free Long-Read Sequencing. J Mol Diagn 2022; 24:1143-1154. [PMID: 36084803 DOI: 10.1016/j.jmoldx.2022.08.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Revised: 07/27/2022] [Accepted: 08/11/2022] [Indexed: 11/20/2022] Open
Abstract
Myotonic dystrophy type 1 (DM1) exhibits highly heterogeneous clinical manifestations caused by an unstable CTG repeat expansion reaching up to 4000 CTG. The clinical variability depends on CTG repeat number, CNG repeat interruptions, and somatic mosaicism. Currently, none of these factors are simultaneously and accurately determined due to the limitations of gold standard methods used in clinical and research laboratories. An amplicon method for targeting the DMPK locus using single-molecule real-time sequencing was recently developed to accurately analyze expanded alleles. However, amplicon-based sequencing still depends on PCR, and the inherent bias toward preferential amplification of smaller repeats can be problematic in DM1. Thus, an amplification-free long-read sequencing method was developed by using CRISPR/Cas9 technology in DM1. This method was used to sequence the DMPK locus in patients with CTG repeat expansion ranging from 130 to >1000 CTG. We showed that elimination of PCR amplification improves the accuracy of measurement of inherited repeat number and somatic repeat variations, two key factors in DM1 severity and age at onset. For the first time, an expansion composed of >85% CCG repeats was identified by using this innovative method in a DM1 family with an atypical clinical profile. No-amplification targeted sequencing represents a promising method that can overcome research and diagnosis shortcomings, with translational implications for clinical and genetic counseling in DM1.
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11
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Intergenerational Influence of Gender and the DM1 Phenotype of the Transmitting Parent in Korean Myotonic Dystrophy Type 1. Genes (Basel) 2022; 13:genes13081465. [PMID: 36011377 PMCID: PMC9408469 DOI: 10.3390/genes13081465] [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: 07/25/2022] [Revised: 08/11/2022] [Accepted: 08/15/2022] [Indexed: 11/18/2022] Open
Abstract
Myotonic dystrophy type 1 (DM1) is the most common autosomal-dominant disorder caused by the CTG repeat expansion of the DMPK, and it has been categorized into three phenotypes: mild, classic, and congenital DM1. Here, we reviewed the intergenerational influence of gender and phenotype of the transmitting parent on the occurrence of Korean DM1. A total of 44 parent–child pairs matched for the gender of the transmitting parent and the affected child and 29 parent–child pairs matched for the gender and DM1 phenotype of the transmitting parent were reviewed. The CTG repeat size of the DMPK in the affected child was found to be significantly greater when transmitted by a female parent to a female child (DM1-FF) (median, 1309 repeats; range, 400–2083) than when transmitted by a male parent to a male child (650; 160–1030; p = 0.038 and 0.048 using the Tukey HSD and the Bonferroni test) or by a male parent to a female child (480; 94–1140; p = 0.003). The difference in the CTG repeat size of the DMPK between the transmitting parent and the affected child was also lower when transmitted from a male parent with classic DM1 (−235; −280 to 0) compared to when it was transmitted from a female parent with mild DM1 (866; 612–905; p = 0.015 and 0.019) or from a female parent with classic DM1 (DM1-FC) (605; 10–1393; p = 0.005). This study highlights that gender and the DM1 phenotype of the transmitting parent had an impact on the CTG repeat size of the DMPK in the affected child, with greater increases being inherited from the DM1-FF or DM1-FC situations in Korean DM1.
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12
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de Pontual L, Tomé S. Overview of the Complex Relationship between Epigenetics Markers, CTG Repeat Instability and Symptoms in Myotonic Dystrophy Type 1. Int J Mol Sci 2022; 23:ijms23073477. [PMID: 35408837 PMCID: PMC8998570 DOI: 10.3390/ijms23073477] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 03/14/2022] [Accepted: 03/16/2022] [Indexed: 02/05/2023] Open
Abstract
Among the trinucleotide repeat disorders, myotonic dystrophy type 1 (DM1) is one of the most complex neuromuscular diseases caused by an unstable CTG repeat expansion in the DMPK gene. DM1 patients exhibit high variability in the dynamics of CTG repeat instability and in the manifestations and progression of the disease. The largest expanded alleles are generally associated with the earliest and most severe clinical form. However, CTG repeat length alone is not sufficient to predict disease severity and progression, suggesting the involvement of other factors. Several data support the role of epigenetic alterations in clinical and genetic variability. By highlighting epigenetic alterations in DM1, this review provides a new avenue on how these changes can serve as biomarkers to predict clinical features and the mutation behavior.
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Affiliation(s)
| | - Stéphanie Tomé
- Correspondence: ; Tel.: +33-1-42-16-57-16; Fax: +33-1-42-16-57-00
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13
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García-Puga M, Saenz-Antoñanzas A, Matheu A, López de Munain A. Targeting Myotonic Dystrophy Type 1 with Metformin. Int J Mol Sci 2022; 23:ijms23052901. [PMID: 35270043 PMCID: PMC8910924 DOI: 10.3390/ijms23052901] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 02/28/2022] [Accepted: 03/02/2022] [Indexed: 02/01/2023] Open
Abstract
Myotonic dystrophy type 1 (DM1) is a multisystemic disorder of genetic origin. Progressive muscular weakness, atrophy and myotonia are its most prominent neuromuscular features, while additional clinical manifestations in multiple organs are also common. Overall, DM1 features resemble accelerated aging. There is currently no cure or specific treatment for myotonic dystrophy patients. However, in recent years a great effort has been made to identify potential new therapeutic strategies for DM1 patients. Metformin is a biguanide antidiabetic drug, with potential to delay aging at cellular and organismal levels. In DM1, different studies revealed that metformin rescues multiple phenotypes of the disease. This review provides an overview of recent findings describing metformin as a novel therapy to combat DM1 and their link with aging.
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Affiliation(s)
- Mikel García-Puga
- Neuromuscular Diseases Group, Biodonostia Health Research Institute, 20014 San Sebastian, Spain;
- Cellular Oncology Group, Biodonostia Health Research Institute, 20014 San Sebastian, Spain;
- Network Center for Biomedical Research in Neurodegenerative Diseases (CIBERNED-CIBER), Carlos III Institute, 28031 Madrid, Spain
| | - Ander Saenz-Antoñanzas
- Cellular Oncology Group, Biodonostia Health Research Institute, 20014 San Sebastian, Spain;
| | - Ander Matheu
- Cellular Oncology Group, Biodonostia Health Research Institute, 20014 San Sebastian, Spain;
- Basque Foundation for Science (IKERBASQUE), 48009 Bilbao, Spain
- Centro de Investigación Biomédica en Red Fragilidad y Envejecimiento Saludable (CIBERfes), Carlos III Institute, 28029 Madrid, Spain
- Correspondence: (A.M.); (A.L.d.M.); Tel.: +34-943-006-073 (A.M.); +34-943-006-294 (A.L.d.M.)
| | - Adolfo López de Munain
- Neuromuscular Diseases Group, Biodonostia Health Research Institute, 20014 San Sebastian, Spain;
- Network Center for Biomedical Research in Neurodegenerative Diseases (CIBERNED-CIBER), Carlos III Institute, 28031 Madrid, Spain
- Neurology Department, Donostia University Hospital, OSAKIDETZA, 20014 San Sebastian, Spain
- Department of Neurosciences, Faculty of Medicine and Nursery, University of the Basque Country, 20014 San Sebastian, Spain
- Correspondence: (A.M.); (A.L.d.M.); Tel.: +34-943-006-073 (A.M.); +34-943-006-294 (A.L.d.M.)
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Myotonic Dystrophies: A Genetic Overview. Genes (Basel) 2022; 13:genes13020367. [PMID: 35205411 PMCID: PMC8872148 DOI: 10.3390/genes13020367] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Revised: 02/09/2022] [Accepted: 02/16/2022] [Indexed: 02/01/2023] Open
Abstract
Myotonic dystrophies (DM) are the most common muscular dystrophies in adults, which can affect other non-skeletal muscle organs such as the heart, brain and gastrointestinal system. There are two genetically distinct types of myotonic dystrophy: myotonic dystrophy type 1 (DM1) and myotonic dystrophy type 2 (DM2), both dominantly inherited with significant overlap in clinical manifestations. DM1 results from CTG repeat expansions in the 3′-untranslated region (3′UTR) of the DMPK (dystrophia myotonica protein kinase) gene on chromosome 19, while DM2 is caused by CCTG repeat expansions in intron 1 of the CNBP (cellular nucleic acid-binding protein) gene on chromosome 3. Recent advances in genetics and molecular biology, especially in the field of RNA biology, have allowed better understanding of the potential pathomechanisms involved in DM. In this review article, core clinical features and genetics of DM are presented followed by a discussion on the current postulated pathomechanisms and therapeutic approaches used in DM, including the ones currently in human clinical trial phase.
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