1
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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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2
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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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Alfano M, De Antoni L, Centofanti F, Visconti VV, Maestri S, Degli Esposti C, Massa R, D'Apice MR, Novelli G, Delledonne M, Botta A, Rossato M. Characterization of full-length CNBP expanded alleles in myotonic dystrophy type 2 patients by Cas9-mediated enrichment and nanopore sequencing. eLife 2022; 11:80229. [PMID: 36018009 PMCID: PMC9462847 DOI: 10.7554/elife.80229] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Accepted: 08/25/2022] [Indexed: 11/30/2022] Open
Abstract
Myotonic dystrophy type 2 (DM2) is caused by CCTG repeat expansions in the CNBP gene, comprising 75 to >11,000 units and featuring extensive mosaicism, making it challenging to sequence fully expanded alleles. To overcome these limitations, we used PCR-free Cas9-mediated nanopore sequencing to characterize CNBP repeat expansions at the single-nucleotide level in nine DM2 patients. The length of normal and expanded alleles can be assessed precisely using this strategy, agreeing with traditional methods, and revealing the degree of mosaicism. We also sequenced an entire ~50 kbp expansion, which has not been achieved previously for DM2 or any other repeat-expansion disorders. Our approach precisely counted the repeats and identified the repeat pattern for both short interrupted and uninterrupted alleles. Interestingly, in the expanded alleles, only two DM2 samples featured the expected pure CCTG repeat pattern, while the other seven presented also TCTG blocks at the 3′ end, which have not been reported before in DM2 patients, but confirmed hereby with orthogonal methods. The demonstrated approach simultaneously determines repeat length, structure/motif, and the extent of somatic mosaicism, promising to improve the molecular diagnosis of DM2 and achieve more accurate genotype–phenotype correlations for the better stratification of DM2 patients in clinical trials.
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Affiliation(s)
| | - Luca De Antoni
- Department of Biotechnology, University of Verona, Verona, Italy
| | - Federica Centofanti
- Department of Biomedicine and Prevention, University of Rome Tor Vergata, Rome, Italy
| | | | - Simone Maestri
- Department of Biotechnology, University of Verona, Verona, Italy
| | | | - Roberto Massa
- Department of Systems Medicine (Neurology), University of Rome Tor Vergata, Rome, Italy
| | | | - Giuseppe Novelli
- Laboratory of Medical Genetics, University of Rome Tor Vergata, Rome, Italy
| | | | - Annalisa Botta
- Department of Biomedicine and Prevention, University of Rome Tor Vergata, Rome, Italy
| | - Marzia Rossato
- Department of Biotechnology, University of Verona, Verona, Italy
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4
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Koehorst E, Odria R, Capó J, Núñez-Manchón J, Arbex A, Almendrote M, Linares-Pardo I, Natera-de Benito D, Saez V, Nascimento A, Ortez C, Rubio MÁ, Díaz-Manera J, Alonso-Pérez J, Lucente G, Rodriguez-Palmero A, Ramos-Fransi A, Martínez-Piñeiro A, Nogales-Gadea G, Suelves M. An Integrative Analysis of DNA Methylation Pattern in Myotonic Dystrophy Type 1 Samples Reveals a Distinct DNA Methylation Profile between Tissues and a Novel Muscle-Associated Epigenetic Dysregulation. Biomedicines 2022; 10:biomedicines10061372. [PMID: 35740394 PMCID: PMC9220235 DOI: 10.3390/biomedicines10061372] [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: 04/22/2022] [Revised: 05/31/2022] [Accepted: 06/07/2022] [Indexed: 11/16/2022] Open
Abstract
Myotonic dystrophy type 1 (DM1) is a progressive, non-treatable, multi-systemic disorder. To investigate the contribution of epigenetics to the complexity of DM1, we compared DNA methylation profiles of four annotated CpG islands (CpGis) in the DMPK locus and neighbouring genes, in distinct DM1 tissues and derived cells, representing six DM1 subtypes, by bisulphite sequencing. In blood, we found no differences in CpGi 74, 43 and 36 in DNA methylation profile. In contrast, a CTCF1 DNA methylation gradient was found with 100% methylation in congenital cases, 50% in childhood cases and 13% in juvenile cases. CTCF1 methylation correlated to disease severity and CTG expansion size. Notably, 50% of CTCF1 methylated cases showed methylation in the CTCF2 regions. Additionally, methylation was associated with maternal transmission. Interestingly, the evaluation of seven families showed that unmethylated mothers passed on an expansion of the CTG repeat, whereas the methylated mothers transmitted a contraction. The analysis of patient-derived cells showed that DNA methylation profiles were highly preserved, validating their use as faithful DM1 cellular models. Importantly, the comparison of DNA methylation levels of distinct DM1 tissues revealed a novel muscle-specific epigenetic signature with methylation of the CTCF1 region accompanied by demethylation of CpGi 43, a region containing an alternative DMPK promoter, which may decrease the canonical promoter activity. Altogether, our results showed a distinct DNA methylation profile across DM1 tissues and uncovered a novel and dual epigenetic signature in DM1 muscle samples, providing novel insights into the epigenetic changes associated with DM1.
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Affiliation(s)
- Emma Koehorst
- Neuromuscular and Neuropediatric Research Group, Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol (IGTP), Campus Can Ruti, Universitat Autònoma de Barcelona, 08916 Badalona, Spain
| | - Renato Odria
- Neuromuscular and Neuropediatric Research Group, Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol (IGTP), Campus Can Ruti, Universitat Autònoma de Barcelona, 08916 Badalona, Spain
| | - Júlia Capó
- Neuromuscular and Neuropediatric Research Group, Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol (IGTP), Campus Can Ruti, Universitat Autònoma de Barcelona, 08916 Badalona, Spain
| | - Judit Núñez-Manchón
- Neuromuscular and Neuropediatric Research Group, Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol (IGTP), Campus Can Ruti, Universitat Autònoma de Barcelona, 08916 Badalona, Spain
| | - Andrea Arbex
- Neuromuscular and Neuropediatric Research Group, Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol (IGTP), Campus Can Ruti, Universitat Autònoma de Barcelona, 08916 Badalona, Spain
- Neuromuscular Pathology Unit, Neurology Service, Neuroscience Department, Hospital Universitari Germans Trias i Pujol, 08916 Badalona, Spain
| | - Miriam Almendrote
- Neuromuscular and Neuropediatric Research Group, Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol (IGTP), Campus Can Ruti, Universitat Autònoma de Barcelona, 08916 Badalona, Spain
- Neuromuscular Pathology Unit, Neurology Service, Neuroscience Department, Hospital Universitari Germans Trias i Pujol, 08916 Badalona, Spain
| | - Ian Linares-Pardo
- Neuromuscular and Neuropediatric Research Group, Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol (IGTP), Campus Can Ruti, Universitat Autònoma de Barcelona, 08916 Badalona, Spain
| | - Daniel Natera-de Benito
- Neuromuscular Unit, Neuropediatric Department, Institut de Recerca Pediàtrica Hospital Sant Joan de Déu, L'Hospitalet de Llobregat, 08950 Barcelona, Spain
| | - Verónica Saez
- Neuromuscular Unit, Neuropediatric Department, Institut de Recerca Pediàtrica Hospital Sant Joan de Déu, L'Hospitalet de Llobregat, 08950 Barcelona, Spain
| | - Andrés Nascimento
- Neuromuscular Unit, Neuropediatric Department, Institut de Recerca Pediàtrica Hospital Sant Joan de Déu, L'Hospitalet de Llobregat, 08950 Barcelona, Spain
| | - Carlos Ortez
- Neuromuscular Unit, Neuropediatric Department, Institut de Recerca Pediàtrica Hospital Sant Joan de Déu, L'Hospitalet de Llobregat, 08950 Barcelona, Spain
| | - Miguel Ángel Rubio
- Neuromuscular Unit, Department of Neurology, Hospital del Mar, 08003 Barcelona, Spain
| | - Jordi Díaz-Manera
- Neuromuscular Diseases Unit, Department of Neurology, Hospital de la Santa Creu i Sant Pau, 08025 Barcelona, Spain
- John Walton Muscular Dystrophy Research Centre, Newcastle University and Newcastle Hospitals NHS Foundation Trust, Newcastle upon Tyne NE1 3BZ, UK
| | - Jorge Alonso-Pérez
- Neuromuscular Diseases Unit, Department of Neurology, Hospital de la Santa Creu i Sant Pau, 08025 Barcelona, Spain
| | - Giuseppe Lucente
- Neuromuscular and Neuropediatric Research Group, Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol (IGTP), Campus Can Ruti, Universitat Autònoma de Barcelona, 08916 Badalona, Spain
- Neuromuscular Pathology Unit, Neurology Service, Neuroscience Department, Hospital Universitari Germans Trias i Pujol, 08916 Badalona, Spain
| | - Agustín Rodriguez-Palmero
- Neuromuscular and Neuropediatric Research Group, Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol (IGTP), Campus Can Ruti, Universitat Autònoma de Barcelona, 08916 Badalona, Spain
- Pediatric Neurology Unit, Department of Pediatrics, Hospital Universitari Germans Trias i Pujol, Universitat Autònoma de Barcelona, 08916 Badalona, Spain
| | - Alba Ramos-Fransi
- Neuromuscular and Neuropediatric Research Group, Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol (IGTP), Campus Can Ruti, Universitat Autònoma de Barcelona, 08916 Badalona, Spain
- Neuromuscular Pathology Unit, Neurology Service, Neuroscience Department, Hospital Universitari Germans Trias i Pujol, 08916 Badalona, Spain
| | - Alicia Martínez-Piñeiro
- Neuromuscular and Neuropediatric Research Group, Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol (IGTP), Campus Can Ruti, Universitat Autònoma de Barcelona, 08916 Badalona, Spain
- Neuromuscular Pathology Unit, Neurology Service, Neuroscience Department, Hospital Universitari Germans Trias i Pujol, 08916 Badalona, Spain
| | - Gisela Nogales-Gadea
- Neuromuscular and Neuropediatric Research Group, Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol (IGTP), Campus Can Ruti, Universitat Autònoma de Barcelona, 08916 Badalona, Spain
| | - Mònica Suelves
- Neuromuscular and Neuropediatric Research Group, Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol (IGTP), Campus Can Ruti, Universitat Autònoma de Barcelona, 08916 Badalona, Spain
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5
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Rasmussen A, Hildonen M, Vissing J, Duno M, Tümer Z, Birkedal U. High Resolution Analysis of DMPK Hypermethylation and Repeat Interruptions in Myotonic Dystrophy Type 1. Genes (Basel) 2022; 13:genes13060970. [PMID: 35741732 PMCID: PMC9222588 DOI: 10.3390/genes13060970] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Revised: 05/19/2022] [Accepted: 05/26/2022] [Indexed: 02/05/2023] Open
Abstract
Myotonic dystrophy type 1 (DM1) is a multisystemic neuromuscular disorder caused by the expansion of a CTG repeat in the 3′-UTR of DMPK, which is transcribed to a toxic gain-of-function RNA that affects splicing of a range of genes. The expanded repeat is unstable in both germline and somatic cells. The variable age at disease onset and severity of symptoms have been linked to the inherited CTG repeat length, non-CTG interruptions, and methylation levels flanking the repeat. In general, the genetic biomarkers are investigated separately with specific methods, making it tedious to obtain an overall characterisation of the repeat for a given individual. In the present study, we employed Oxford nanopore sequencing in a pilot study to simultaneously determine the repeat lengths, investigate the presence and nature of repeat interruptions, and quantify methylation levels in the regions flanking the CTG-repeats in four patients with DM1. We determined the repeat lengths, and in three patients, we observed interruptions which were not detected using repeat-primed PCR. Interruptions may thus be more common than previously anticipated and should be investigated in larger cohorts. Allele-specific analyses enabled characterisation of aberrant methylation levels specific to the expanded allele, which greatly increased the sensitivity and resolved cases where the methylation levels were ambiguous.
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Affiliation(s)
- Astrid Rasmussen
- Kennedy Center, Department of Clinical Genetics, Copenhagen University Hospital, Rigshospitalet, 2600 Glostrup, Denmark; (A.R.); (M.H.); (U.B.)
| | - Mathis Hildonen
- Kennedy Center, Department of Clinical Genetics, Copenhagen University Hospital, Rigshospitalet, 2600 Glostrup, Denmark; (A.R.); (M.H.); (U.B.)
| | - John Vissing
- Copenhagen Neuromuscular Center, Department of Neurology, Copenhagen University Hospital, Rigshospitalet, 2100 Copenhagen, Denmark;
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Morten Duno
- Department of Clinical Genetics, Copenhagen University Hospital, Rigshospitalet, 2100 Copenhagen, Denmark;
| | - Zeynep Tümer
- Kennedy Center, Department of Clinical Genetics, Copenhagen University Hospital, Rigshospitalet, 2600 Glostrup, Denmark; (A.R.); (M.H.); (U.B.)
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
- Correspondence:
| | - Ulf Birkedal
- Kennedy Center, Department of Clinical Genetics, Copenhagen University Hospital, Rigshospitalet, 2600 Glostrup, Denmark; (A.R.); (M.H.); (U.B.)
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6
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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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7
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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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8
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Molecular and Clinical Implications of Variant Repeats in Myotonic Dystrophy Type 1. Int J Mol Sci 2021; 23:ijms23010354. [PMID: 35008780 PMCID: PMC8745394 DOI: 10.3390/ijms23010354] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Revised: 12/14/2021] [Accepted: 12/18/2021] [Indexed: 12/13/2022] Open
Abstract
Myotonic dystrophy type 1 (DM1) is one of the most variable monogenic diseases at phenotypic, genetic, and epigenetic level. The disease is multi-systemic with the age at onset ranging from birth to late age. The underlying mutation is an unstable expansion of CTG repeats in the DMPK gene, varying in size from 50 to >1000 repeats. Generally, large expansions are associated with an earlier age at onset. Additionally, the most severe, congenital DM1 form is typically associated with local DNA methylation. Genetic variability of DM1 mutation is further increased by its structural variations due to presence of other repeats (e.g., CCG, CTC, CAG). These variant repeats or repeat interruptions seem to confer an additional level of epigenetic variability since local DNA methylation is frequently associated with variant CCG repeats independently of the expansion size. The effect of repeat interruptions on DM1 molecular pathogenesis is not investigated enough. Studies on patients indicate their stabilizing effect on DMPK expansions because no congenital cases were described in patients with repeat interruptions, and the age at onset is frequently later than expected. Here, we review the clinical relevance of repeat interruptions in DM1 and genetic and epigenetic characteristics of interrupted DMPK expansions based on patient studies.
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Visconti VV, Centofanti F, Fittipaldi S, Macrì E, Novelli G, Botta A. Epigenetics of Myotonic Dystrophies: A Minireview. Int J Mol Sci 2021; 22:ijms222212594. [PMID: 34830473 PMCID: PMC8623789 DOI: 10.3390/ijms222212594] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Revised: 11/19/2021] [Accepted: 11/20/2021] [Indexed: 12/14/2022] Open
Abstract
Myotonic dystrophy type 1 and 2 (DM1 and DM2) are two multisystemic autosomal dominant disorders with clinical and genetic similarities. The prevailing paradigm for DMs is that they are mediated by an in trans toxic RNA mechanism, triggered by untranslated CTG and CCTG repeat expansions in the DMPK and CNBP genes for DM1 and DM2, respectively. Nevertheless, increasing evidences suggest that epigenetics can also play a role in the pathogenesis of both diseases. In this review, we discuss the available information on epigenetic mechanisms that could contribute to the DMs outcome and progression. Changes in DNA cytosine methylation, chromatin remodeling and expression of regulatory noncoding RNAs are described, with the intent of depicting an epigenetic signature of DMs. Epigenetic biomarkers have a strong potential for clinical application since they could be used as targets for therapeutic interventions avoiding changes in DNA sequences. Moreover, understanding their clinical significance may serve as a diagnostic indicator in genetic counselling in order to improve genotype–phenotype correlations in DM patients.
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Affiliation(s)
- Virginia Veronica Visconti
- Department of Biomedicine and Prevention, Medical Genetics Section, University of Rome “Tor Vergata”, Via Montpellier 1, 00133 Rome, Italy; (V.V.V.); (F.C.); (S.F.); (E.M.); (G.N.)
| | - Federica Centofanti
- Department of Biomedicine and Prevention, Medical Genetics Section, University of Rome “Tor Vergata”, Via Montpellier 1, 00133 Rome, Italy; (V.V.V.); (F.C.); (S.F.); (E.M.); (G.N.)
| | - Simona Fittipaldi
- Department of Biomedicine and Prevention, Medical Genetics Section, University of Rome “Tor Vergata”, Via Montpellier 1, 00133 Rome, Italy; (V.V.V.); (F.C.); (S.F.); (E.M.); (G.N.)
| | - Elisa Macrì
- Department of Biomedicine and Prevention, Medical Genetics Section, University of Rome “Tor Vergata”, Via Montpellier 1, 00133 Rome, Italy; (V.V.V.); (F.C.); (S.F.); (E.M.); (G.N.)
| | - Giuseppe Novelli
- Department of Biomedicine and Prevention, Medical Genetics Section, University of Rome “Tor Vergata”, Via Montpellier 1, 00133 Rome, Italy; (V.V.V.); (F.C.); (S.F.); (E.M.); (G.N.)
- IRCCS (Institute for Treatment and Research) Neuromed, 86077 Pozzilli, Italy
- Department of Pharmacology, School of Medicine, University of Nevada, Reno, NV 89557, USA
| | - Annalisa Botta
- Department of Biomedicine and Prevention, Medical Genetics Section, University of Rome “Tor Vergata”, Via Montpellier 1, 00133 Rome, Italy; (V.V.V.); (F.C.); (S.F.); (E.M.); (G.N.)
- Correspondence: ; Tel.: +39-6-7259-6078
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10
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Mangin A, de Pontual L, Tsai YC, Monteil L, Nizon M, Boisseau P, Mercier S, Ziegle J, Harting J, Heiner C, Gourdon G, Tomé S. Robust Detection of Somatic Mosaicism and Repeat Interruptions by Long-Read Targeted Sequencing in Myotonic Dystrophy Type 1. Int J Mol Sci 2021; 22:2616. [PMID: 33807660 PMCID: PMC7962047 DOI: 10.3390/ijms22052616] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 02/26/2021] [Accepted: 02/27/2021] [Indexed: 02/07/2023] Open
Abstract
Myotonic dystrophy type 1 (DM1) is the most complex and variable trinucleotide repeat disorder caused by an unstable CTG repeat expansion, reaching up to 4000 CTG in the most severe cases. The genetic and clinical variability of DM1 depend on the sex and age of the transmitting parent, but also on the CTG repeat number, presence of repeat interruptions and/or on the degree of somatic instability. Currently, it is difficult to simultaneously and accurately determine these contributing factors in DM1 patients due to the limitations of gold standard methods used in molecular diagnostics and research laboratories. Our study showed the efficiency of the latest PacBio long-read sequencing technology to sequence large CTG trinucleotides, detect multiple and single repeat interruptions and estimate the levels of somatic mosaicism in DM1 patients carrying complex CTG repeat expansions inaccessible to most methods. Using this innovative approach, we revealed the existence of de novo CCG interruptions associated with CTG stabilization/contraction across generations in a new DM1 family. We also demonstrated that our method is suitable to sequence the DM1 locus and measure somatic mosaicism in DM1 families carrying more than 1000 pure CTG repeats. Better characterization of expanded alleles in DM1 patients can significantly improve prognosis and genetic counseling, not only in DM1 but also for other tandem DNA repeat disorders.
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Affiliation(s)
- Antoine Mangin
- Centre de Recherche en Myologie, Inserm, Institut de Myologie, Sorbonne Université, F-75013 Paris, France; (A.M.); (L.d.P.); (G.G.)
- Dementia Research Institute, Cardiff University, Cardiff CF10 3AT, UK
| | - Laure de Pontual
- Centre de Recherche en Myologie, Inserm, Institut de Myologie, Sorbonne Université, F-75013 Paris, France; (A.M.); (L.d.P.); (G.G.)
| | - Yu-Chih Tsai
- Pacific Biosciences, Menlo Park, CA 94025, USA; (Y.-C.T.); (J.Z.); (J.H.); (C.H.)
| | - Laetitia Monteil
- Genetics Department of the Hospital of Toulouse, F-31059 Toulouse, France;
| | - Mathilde Nizon
- CHU de Nantes, Service de Génétique Médicale, Laboratoire de Génétique Moléculaire, F-44000 Nantes, France; (M.N.); (P.B.)
| | - Pierre Boisseau
- CHU de Nantes, Service de Génétique Médicale, Laboratoire de Génétique Moléculaire, F-44000 Nantes, France; (M.N.); (P.B.)
| | - Sandra Mercier
- CHU Nantes, Service de Génétique Médicale, Centre de Référence des Maladies Neuromusculaires AOC, F-44000 Nantes, France;
| | - Janet Ziegle
- Pacific Biosciences, Menlo Park, CA 94025, USA; (Y.-C.T.); (J.Z.); (J.H.); (C.H.)
| | - John Harting
- Pacific Biosciences, Menlo Park, CA 94025, USA; (Y.-C.T.); (J.Z.); (J.H.); (C.H.)
| | - Cheryl Heiner
- Pacific Biosciences, Menlo Park, CA 94025, USA; (Y.-C.T.); (J.Z.); (J.H.); (C.H.)
| | - Geneviève Gourdon
- Centre de Recherche en Myologie, Inserm, Institut de Myologie, Sorbonne Université, F-75013 Paris, France; (A.M.); (L.d.P.); (G.G.)
| | - Stéphanie Tomé
- Centre de Recherche en Myologie, Inserm, Institut de Myologie, Sorbonne Université, F-75013 Paris, France; (A.M.); (L.d.P.); (G.G.)
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11
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Johnson SJ, Cooper TA. Overlapping mechanisms of lncRNA and expanded microsatellite RNA. WILEY INTERDISCIPLINARY REVIEWS. RNA 2021; 12:e1634. [PMID: 33191580 PMCID: PMC7880542 DOI: 10.1002/wrna.1634] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 10/14/2020] [Accepted: 10/20/2020] [Indexed: 12/15/2022]
Abstract
RNA has major regulatory roles in a wide range of biological processes and a surge of RNA research has led to the classification of numerous functional RNA species. One example is long noncoding RNAs (lncRNAs) that are structurally complex transcripts >200 nucleotides (nt) in length and lacking a canonical open reading frame (ORF). Despite a general lack of sequence conservation and low expression levels, many lncRNAs have been shown to have functionality in diverse biological processes as well as in mechanisms of disease. In parallel with the growing understanding of lncRNA functions, there is a growing subset of microsatellite expansion disorders in which the primary mechanism of pathogenesis is an RNA gain of function arising from RNA transcripts from the mutant allele. Microsatellite expansion disorders are caused by an expansion of short (3-10 nt) repeats located within coding genes. Expanded repeat-containing RNA mediates toxicity through multiple mechanisms, the details of which remain only partially understood. The purpose of this review is to highlight the links between functional mechanisms of lncRNAs and the potential pathogenic mechanisms of expanded microsatellite RNA. These shared mechanisms include protein sequestration, peptide translation, micro-RNA (miRNA) processing, and miRNA sequestration. Recognizing the parallels between the normal functions of lncRNAs and the negative impact of expanded microsatellite RNA on biological processes can provide reciprocal understanding to the roles of both RNA species. This article is categorized under: RNA Interactions with Proteins and Other Molecules > Protein-RNA Interactions: Functional Implications RNA in Disease and Development > RNA in Disease.
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Affiliation(s)
- Sara J Johnson
- Department of Molecular & Cellular Biology, Baylor College of Medicine, Houston, Texas, USA
| | - Thomas A Cooper
- Department of Molecular & Cellular Biology, Baylor College of Medicine, Houston, Texas, USA
- Department of Pathology & Immunology, Baylor College of Medicine, Houston, Texas, USA
- Department of Physiology and Biophysics, Baylor College of Medicine, Houston, Texas, USA
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12
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Breton É, Légaré C, Overend G, Guay SP, Monckton D, Mathieu J, Gagnon C, Richer L, Gallais B, Bouchard L. DNA methylation at the DMPK gene locus is associated with cognitive functions in myotonic dystrophy type 1. Epigenomics 2020; 12:2051-2064. [PMID: 33301350 DOI: 10.2217/epi-2020-0328] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Aim: Myotonic dystrophy type 1 (DM1) is caused by an unstable trinucleotide (CTG) expansion at the DMPK gene locus. Cognitive dysfunctions are often observed in the condition. We investigated the association between DMPK blood DNA methylation (DNAm) and cognitive functions in DM1, considering expansion length and variant repeats (VRs). Method: Data were obtained from 115 adult-onset DM1 patients. Molecular analyses consisted of pyrosequencing, small pool PCR and Southern blot hybridization. Cognitive functions were assessed by validated neuropsychological tests. Results: For patients without VRs (n = 103), blood DNAm at baseline independently contributed to predict cognitive functions 9 years later. Patients with VRs (n = 12) had different DNAm and cognitive profiles. Conclusion: DNAm allows to better understand DM1-related cognitive dysfunction etiology.
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Affiliation(s)
- Édith Breton
- Department of Biochemistry & Functional Genomics, Université de Sherbrooke, Sherbrooke, Québec J1E 4K8, Canada.,Groupe de recherche interdisciplinaire sur les maladies neuromusculaires (GRIMN), Centre intégré universitaire de santé et de services sociaux (CIUSSS) du Saguenay-Lac-St-Jean - Hôpital de Jonquière, Saguenay, Québec G7X 7X2, Canada
| | - Cécilia Légaré
- Department of Biochemistry & Functional Genomics, Université de Sherbrooke, Sherbrooke, Québec J1E 4K8, Canada.,Groupe de recherche interdisciplinaire sur les maladies neuromusculaires (GRIMN), Centre intégré universitaire de santé et de services sociaux (CIUSSS) du Saguenay-Lac-St-Jean - Hôpital de Jonquière, Saguenay, Québec G7X 7X2, Canada
| | - Gayle Overend
- Institute of Molecular, Cell & Systems Biology, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Simon-Pierre Guay
- Department of Biochemistry & Functional Genomics, Université de Sherbrooke, Sherbrooke, Québec J1E 4K8, Canada.,Department of Specialized Medicine, Division of Medical Genetics, McGill University Health Centre, Montreal, QC H4A 3J1, Canada
| | - Darren Monckton
- Institute of Molecular, Cell & Systems Biology, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Jean Mathieu
- Groupe de recherche interdisciplinaire sur les maladies neuromusculaires (GRIMN), Centre intégré universitaire de santé et de services sociaux (CIUSSS) du Saguenay-Lac-St-Jean - Hôpital de Jonquière, Saguenay, Québec G7X 7X2, Canada.,Centre de recherche Charles-Le-Moyne-Saguenay-Lac-Saint-Jean sur les innovations en santé (CR-CSIS), Université de Sherbrooke, Saguenay, Québec G7H 5H6, Canada
| | - Cynthia Gagnon
- Groupe de recherche interdisciplinaire sur les maladies neuromusculaires (GRIMN), Centre intégré universitaire de santé et de services sociaux (CIUSSS) du Saguenay-Lac-St-Jean - Hôpital de Jonquière, Saguenay, Québec G7X 7X2, Canada.,Centre de recherche Charles-Le-Moyne-Saguenay-Lac-Saint-Jean sur les innovations en santé (CR-CSIS), Université de Sherbrooke, Saguenay, Québec G7H 5H6, Canada
| | - Louis Richer
- Groupe de recherche interdisciplinaire sur les maladies neuromusculaires (GRIMN), Centre intégré universitaire de santé et de services sociaux (CIUSSS) du Saguenay-Lac-St-Jean - Hôpital de Jonquière, Saguenay, Québec G7X 7X2, Canada.,Department of Health Sciences, Université du Québec à Chicoutimi (UQAC), Saguenay, Québec G7H 2B1, Canada
| | - Benjamin Gallais
- Groupe de recherche interdisciplinaire sur les maladies neuromusculaires (GRIMN), Centre intégré universitaire de santé et de services sociaux (CIUSSS) du Saguenay-Lac-St-Jean - Hôpital de Jonquière, Saguenay, Québec G7X 7X2, Canada.,Centre de recherche Charles-Le-Moyne-Saguenay-Lac-Saint-Jean sur les innovations en santé (CR-CSIS), Université de Sherbrooke, Saguenay, Québec G7H 5H6, Canada.,ÉCOBES - Recherche et transfert, Cégep de Jonquière, Saguenay, Québec G7X 7W2, Canada
| | - Luigi Bouchard
- Department of Biochemistry & Functional Genomics, Université de Sherbrooke, Sherbrooke, Québec J1E 4K8, Canada.,Groupe de recherche interdisciplinaire sur les maladies neuromusculaires (GRIMN), Centre intégré universitaire de santé et de services sociaux (CIUSSS) du Saguenay-Lac-St-Jean - Hôpital de Jonquière, Saguenay, Québec G7X 7X2, Canada.,Department of Medical Biology, Centre intégré universitaire de santé et de services sociaux (CIUSSS) du Saguenay-Lac-St-Jean - Hôpital de Chicoutimi, Saguenay, Québec G7H 5H6, Canada
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13
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Abstract
Neuromuscular disorders are a heterogeneous group of conditions affecting the neuromuscular system. The aim of this article is to review the major epigenetic findings in motor neuron diseases and major hereditary muscular dystrophies. DNA methylation changes are observed in both hereditary and sporadic forms, and combining DNA methylation analysis with mutational screening holds the potential for better diagnostic and prognostic accuracy. Novel, less toxic and more selective epigenetic drugs are designed and tested in animal and cell culture models of neuromuscular disorders, and non-coding RNAs are being investigated as either disease biomarkers or targets of therapeutic approaches to restore gene expression levels. Overall, neuromuscular disorder epigenetic biomarkers have a strong potential for clinical applications in the near future.
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Affiliation(s)
- Fabio Coppedè
- Department of Translational Research & of New Surgical & Medical Technologies, University of Pisa, Via Roma 55, 56126 Pisa, Italy
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14
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Santoro M, Perna A, La Rosa P, Petrillo S, Piemonte F, Rossi S, Riso V, Nicoletti TF, Modoni A, Pomponi MG, Chiurazzi P, Silvestri G. Compound heterozygosity for an expanded (GAA) and a (GAAGGA) repeat at FXN locus: from a diagnostic pitfall to potential clues to the pathogenesis of Friedreich ataxia. Neurogenetics 2020; 21:279-287. [PMID: 32638185 DOI: 10.1007/s10048-020-00620-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Accepted: 06/14/2020] [Indexed: 12/23/2022]
Abstract
Friedreich's ataxia (FRDA) is usually due to a homozygous GAA expansion in intron 1 of the frataxin (FXN) gene. Rarely, uncommon molecular rearrangements at the FXN locus can cause pitfalls in the molecular diagnosis of FRDA. Here we describe a family whose proband was affected by late-onset Friedreich's ataxia (LOFA); long-range PCR (LR-PCR) documented two small expanded GAA alleles both in the proband and in her unaffected younger sister, who therefore received a diagnosis of pre-symptomatic LOFA. Later studies, however, revealed that the proband's unaffected sister, as well as their healthy mother, were both carriers of an expanded GAA allele and an uncommon (GAAGGA)66-67 repeat mimicking a GAA expansion at the LR-PCR that was the cause of the wrong initial diagnosis of pre-symptomatic LOFA. Extensive studies in tissues from all the family members, including LR-PCR, assessment of methylation status of FXN locus, MboII restriction analysis and direct sequencing of LR-PCR products, analysis of FXN mRNA, and frataxin protein expression, support the virtual lack of pathogenicity of the rare (GAAGGA)66-67 repeat, also providing significant data about the modulation of epigenetic modifications at the FXN locus. Overall, this report highlights a rare but possible pitfall in FRDA molecular diagnosis, emphasizing the need of further analysis in case of discrepancy between clinical and molecular data.
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Affiliation(s)
- Massimo Santoro
- IRCCS Fondazione Don Carlo Gnocchi, Piazzale Morandi, 6, 20121, Milan, Italy
| | - Alessia Perna
- Dept of Neuroscience, Faculty of Medicine and Surgery, Università Cattolica del Scaro Cuore, L.go F. Vito 1, 000168, Rome, Italy
| | - Piergiorgio La Rosa
- Unit of Muscular and Neurodegenerative Diseases, Ospedale Pediatrico Bambino Gesù, IRCCS, Viale San Paolo, 15, 00146, Rome, Italy
| | - Sara Petrillo
- Unit of Muscular and Neurodegenerative Diseases, Ospedale Pediatrico Bambino Gesù, IRCCS, Viale San Paolo, 15, 00146, Rome, Italy
| | - Fiorella Piemonte
- Unit of Muscular and Neurodegenerative Diseases, Ospedale Pediatrico Bambino Gesù, IRCCS, Viale San Paolo, 15, 00146, Rome, Italy
| | - Salvatore Rossi
- Dept of Neuroscience, Faculty of Medicine and Surgery, Università Cattolica del Scaro Cuore, L.go F. Vito 1, 000168, Rome, Italy
| | - Vittorio Riso
- Dept of Neuroscience, Faculty of Medicine and Surgery, Università Cattolica del Scaro Cuore, L.go F. Vito 1, 000168, Rome, Italy
- Institute of Neurology, Neuroscience Area, Neurology Unit, Fondazione Policlinico Universitario A. Gemelli IRCCS, Largo Agostino Gemelli, 8, 00168, Rome, Italy
| | - Tommaso Filippo Nicoletti
- Dept of Neuroscience, Faculty of Medicine and Surgery, Università Cattolica del Scaro Cuore, L.go F. Vito 1, 000168, Rome, Italy
- Institute of Neurology, Neuroscience Area, Neurology Unit, Fondazione Policlinico Universitario A. Gemelli IRCCS, Largo Agostino Gemelli, 8, 00168, Rome, Italy
| | - Anna Modoni
- Institute of Neurology, Neuroscience Area, Neurology Unit, Fondazione Policlinico Universitario A. Gemelli IRCCS, Largo Agostino Gemelli, 8, 00168, Rome, Italy
| | - Maria Grazia Pomponi
- Institute of Genomic Medicine, Università Cattolica del Sacro Cuore, Fondazione Policlinico Universitario A. Gemelli IRCCS, Largo Agostino Gemelli, 8, 00168, Rome, Italy
| | - Pietro Chiurazzi
- Institute of Genomic Medicine, Università Cattolica del Sacro Cuore, Fondazione Policlinico Universitario A. Gemelli IRCCS, Largo Agostino Gemelli, 8, 00168, Rome, Italy
| | - Gabriella Silvestri
- Dept of Neuroscience, Faculty of Medicine and Surgery, Università Cattolica del Scaro Cuore, L.go F. Vito 1, 000168, Rome, Italy.
- Institute of Neurology, Neuroscience Area, Neurology Unit, Fondazione Policlinico Universitario A. Gemelli IRCCS, Largo Agostino Gemelli, 8, 00168, Rome, Italy.
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15
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Hildonen M, Knak KL, Dunø M, Vissing J, Tümer Z. Stable Longitudinal Methylation Levels at the CpG Sites Flanking the CTG Repeat of DMPK in Patients with Myotonic Dystrophy Type 1. Genes (Basel) 2020; 11:genes11080936. [PMID: 32823742 PMCID: PMC7465187 DOI: 10.3390/genes11080936] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Revised: 08/10/2020] [Accepted: 08/10/2020] [Indexed: 12/11/2022] Open
Abstract
Myotonic dystrophy type 1 (DM1) is an autosomal dominant multisystem disorder mainly characterized by gradual muscle loss, weakness, and delayed relaxation after muscle contraction. It is caused by an expanded CTG repeat in the 3′ UTR of DMPK, which is transcribed into a toxic gain-of-function mRNA that affects the splicing of a range of other genes. The repeat is unstable, with a bias towards expansions both in somatic cells and in the germline, which results in a tendency for earlier onset with each generation, as longer repeat lengths generally correlate with earlier onset. Previous studies have found hypermethylation in the regions flanking the repeat in congenital onset DM1 and in some patients with non-congenital DM1. We used pyrosequencing to investigate blood methylation levels in 68 patients with non-congenital DM1, compare the methylation levels between the blood and muscle, and assess whether methylation levels change over time in the blood. We found higher methylation levels in the blood of DM1 patients than in healthy controls and especially in the patients who had inherited the disease allele maternally. The methylation levels remained relatively stable over time and are a strong biomarker of the disease, as well as of the maternal inheritance of the disease.
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Affiliation(s)
- Mathis Hildonen
- Kennedy Center, Department of Clinical Genetics, Copenhagen University Hospital, Rigshospitalet, 2600 Glostrup, Denmark;
| | - Kirsten Lykke Knak
- Department of Neurology, Copenhagen University Hospital, Rigshospitalet, 2100 Copenhagen, Denmark; (K.L.K.); (J.V.)
| | - Morten Dunø
- Department of Clinical Genetics, Copenhagen University Hospital, Rigshospitalet, 2100 Copenhagen, Denmark;
| | - John Vissing
- Department of Neurology, Copenhagen University Hospital, Rigshospitalet, 2100 Copenhagen, Denmark; (K.L.K.); (J.V.)
| | - Zeynep Tümer
- Kennedy Center, Department of Clinical Genetics, Copenhagen University Hospital, Rigshospitalet, 2600 Glostrup, Denmark;
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
- Correspondence: ; Tel.: +45-2920-4855
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16
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DNA Methylation in the Diagnosis of Monogenic Diseases. Genes (Basel) 2020; 11:genes11040355. [PMID: 32224912 PMCID: PMC7231024 DOI: 10.3390/genes11040355] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Revised: 03/13/2020] [Accepted: 03/24/2020] [Indexed: 02/08/2023] Open
Abstract
DNA methylation in the human genome is largely programmed and shaped by transcription factor binding and interaction between DNA methyltransferases and histone marks during gamete and embryo development. Normal methylation profiles can be modified at single or multiple loci, more frequently as consequences of genetic variants acting in cis or in trans, or in some cases stochastically or through interaction with environmental factors. For many developmental disorders, specific methylation patterns or signatures can be detected in blood DNA. The recent use of high-throughput assays investigating the whole genome has largely increased the number of diseases for which DNA methylation analysis provides information for their diagnosis. Here, we review the methylation abnormalities that have been associated with mono/oligogenic diseases, their relationship with genotype and phenotype and relevance for diagnosis, as well as the limitations in their use and interpretation of results.
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17
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Fontana L, Santoro M, D'Apice MR, Peluso F, Gori G, Morrone A, Novelli G, Dosa L, Botta A. Identification, molecular characterization and segregation analysis of a variant DMPK pre-mutation allele in a three-generation Italian family. ACTA MYOLOGICA : MYOPATHIES AND CARDIOMYOPATHIES : OFFICIAL JOURNAL OF THE MEDITERRANEAN SOCIETY OF MYOLOGY 2020; 39:13-18. [PMID: 32607474 PMCID: PMC7315898 DOI: 10.36185/2532-1900-002] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Accepted: 03/05/2020] [Indexed: 12/19/2022]
Abstract
DM1 is an autosomal dominant multisystemic disease caused by an unstable CTG repeat expansion in the 3'-untranslated region (UTR) of the DMPK gene. The complex variant DMPK expanded the alleles containing CAG, CCG, CTC and/or GGC interruptions repetition sequences have been reported in 3-8% of DM1 patients. To date, very few information is available about the frequency and clinical consequences of pre-mutated DMPK variant allele. In this study, we describe a three-generation Italian family showing the segregation of an interrupted DMPK allele within the premutation range. TP-PCR with primers complementary to CCG repetitions and direct sequencing allow us to identify a hetero-triplet (CTG)6(CCGCTG)15(CTG)5 repeat structure. The haplotype analysis demonstrated that this variant allele is associated with the European founder DM1 haplotype. The pyrosequencing analysis of the CpG islands contained in the flanking regions of the CTG array, did not show the presence of a cis effect of the CCG interruptions on the methylation profile of the DM1 locus. The analysis of both meiotic transmissions, one maternal and one paternal, revealed the intrafamilial stability of the DM1 premutation among relatives. Our findings further support the hypothesis of a stabilizing effect of CCG interruptions on the mutational dynamics of the DM1 locus, also in intermediate DMPK alleles.
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Affiliation(s)
- Luana Fontana
- Department of Biomedicine and Prevention, University of Rome Tor Vergata, Rome, Italy
| | | | | | - Francesca Peluso
- Medical Genetics Unit, Department of Biomedical Experimental and Clinical Sciences "Mario Serio", University of Florence, Florence, Italy
| | - Giulia Gori
- Medical Genetics Section, Tor Vergata Hospital, Rome, Italy
| | - Amelia Morrone
- Neuroscience Department, Meyer Children's Hospital, Florence, Italy
| | - Giuseppe Novelli
- Department of Biomedicine and Prevention, University of Rome Tor Vergata, Rome, Italy.,Medical Genetics Section, Tor Vergata Hospital, Rome, Italy.,Neuromed IRCCS Institute, Pozzilli, Isernia, Italy
| | - Laura Dosa
- Medical Genetics Unit, Anna Meyer Children's University Hospital, Florence, Italy
| | - Annalisa Botta
- Department of Biomedicine and Prevention, University of Rome Tor Vergata, Rome, Italy
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18
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Ballester-Lopez A, Koehorst E, Almendrote M, Martínez-Piñeiro A, Lucente G, Linares-Pardo I, Núñez-Manchón J, Guanyabens N, Cano A, Lucia A, Overend G, Cumming SA, Monckton DG, Casadevall T, Isern I, Sánchez-Ojanguren J, Planas A, Rodríguez-Palmero A, Monlleó-Neila L, Pintos-Morell G, Ramos-Fransi A, Coll-Cantí J, Nogales-Gadea G. A DM1 family with interruptions associated with atypical symptoms and late onset but not with a milder phenotype. Hum Mutat 2019; 41:420-431. [PMID: 31608518 DOI: 10.1002/humu.23932] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Revised: 09/18/2019] [Accepted: 10/06/2019] [Indexed: 12/16/2022]
Abstract
Carriage of interruptions in CTG repeats of the myotonic dystrophy protein kinase gene has been associated with a broad spectrum of myotonic dystrophy type 1 (DM1) phenotypes, mostly mild. However, the data available on interrupted DM1 patients and their phenotype are scarce. We studied 49 Spanish DM1 patients, whose clinical phenotype was evaluated in depth. Blood DNA was obtained and analyzed through triplet-primed polymerase chain reaction (PCR), long PCR-Southern blot, small pool PCR, AciI digestion, and sequencing. Five patients of our registry (10%), belonging to the same family, carried CCG interruptions at the 3'-end of the CTG expansion. Some of them presented atypical traits such as very late onset of symptoms ( > 50 years) and a severe axial and proximal weakness requiring walking assistance. They also showed classic DM1 symptoms including cardiac and respiratory dysfunction, which were severe in some of them. Sizes and interrupted allele patterns were determined, and we found a contraction and an expansion in two intergenerational transmissions. Our study contributes to the observation that DM1 patients carrying interruptions present with atypical clinical features that can make DM1 diagnosis difficult, with a later than expected age of onset and a previously unreported aging-related severe disease manifestation.
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Affiliation(s)
- Alfonsina Ballester-Lopez
- Neuromuscular and Neuropediatric Research Group, Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol, Campus Can Ruti, Universitat Autònoma de Barcelona, Badalona, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III, Madrid, Spain
| | - Emma Koehorst
- Neuromuscular and Neuropediatric Research Group, Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol, Campus Can Ruti, Universitat Autònoma de Barcelona, Badalona, Spain
| | - Miriam Almendrote
- Neuromuscular and Neuropediatric Research Group, Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol, Campus Can Ruti, Universitat Autònoma de Barcelona, Badalona, Spain.,Neuromuscular Pathology Unit, Neurology Service, Neuroscience Department, Hospital Universitari Germans Trias i Pujol, Barcelona, Spain
| | - Alicia Martínez-Piñeiro
- Neuromuscular and Neuropediatric Research Group, Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol, Campus Can Ruti, Universitat Autònoma de Barcelona, Badalona, Spain.,Neuromuscular Pathology Unit, Neurology Service, Neuroscience Department, Hospital Universitari Germans Trias i Pujol, Barcelona, Spain
| | - Giuseppe Lucente
- Neuromuscular and Neuropediatric Research Group, Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol, Campus Can Ruti, Universitat Autònoma de Barcelona, Badalona, Spain.,Neuromuscular Pathology Unit, Neurology Service, Neuroscience Department, Hospital Universitari Germans Trias i Pujol, Barcelona, Spain
| | - Ian Linares-Pardo
- Neuromuscular and Neuropediatric Research Group, Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol, Campus Can Ruti, Universitat Autònoma de Barcelona, Badalona, Spain
| | - Judit Núñez-Manchón
- Neuromuscular and Neuropediatric Research Group, Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol, Campus Can Ruti, Universitat Autònoma de Barcelona, Badalona, Spain
| | - Nicolau Guanyabens
- Neuromuscular Pathology Unit, Neurology Service, Neuroscience Department, Hospital Universitari Germans Trias i Pujol, Barcelona, Spain
| | - Antoni Cano
- Neurology Unit, Neuroscience Department, Hospital de Mataró, Barcelona, Spain
| | - Alejandro Lucia
- Universidad Europea (Faculty of Sport Sciences), Madrid, Spain.,Instituto de Investigación Hospital 12 de Octubre (i+12), Madrid, Spain
| | - Gayle Overend
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Sarah A Cumming
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Darren G Monckton
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Teresa Casadevall
- Neurology Service, Hospital Comarcal Sant Jaume de Calella, Barcelona, Spain
| | - Irina Isern
- Unitat de Neurologia, Hospital de l'Esperit Sant, Barcelona, Spain
| | | | - Albert Planas
- Servei de medicina interna, Secció de neurologia, Hospital Municipal de Badalona, Barcelona, Spain
| | - Agustí Rodríguez-Palmero
- Neuromuscular and Neuropediatric Research Group, Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol, Campus Can Ruti, Universitat Autònoma de Barcelona, Badalona, Spain.,Neuropediatric Unit, Pediatric Service, Hospital Universitari Germans Trias i Pujol, Barcelona, Spain
| | - Laura Monlleó-Neila
- Neuromuscular and Neuropediatric Research Group, Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol, Campus Can Ruti, Universitat Autònoma de Barcelona, Badalona, Spain.,Neuropediatric Unit, Pediatric Service, Hospital Universitari Germans Trias i Pujol, Barcelona, Spain
| | - Guillem Pintos-Morell
- Neuromuscular and Neuropediatric Research Group, Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol, Campus Can Ruti, Universitat Autònoma de Barcelona, Badalona, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III, Madrid, Spain.,Division of Rare Diseases, University Hospital Vall d'Hebron, Barcelona, Spain
| | - Alba Ramos-Fransi
- Neuromuscular and Neuropediatric Research Group, Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol, Campus Can Ruti, Universitat Autònoma de Barcelona, Badalona, Spain.,Neuromuscular Pathology Unit, Neurology Service, Neuroscience Department, Hospital Universitari Germans Trias i Pujol, Barcelona, Spain
| | - Jaume Coll-Cantí
- Neuromuscular and Neuropediatric Research Group, Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol, Campus Can Ruti, Universitat Autònoma de Barcelona, Badalona, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III, Madrid, Spain.,Neuromuscular Pathology Unit, Neurology Service, Neuroscience Department, Hospital Universitari Germans Trias i Pujol, Barcelona, Spain
| | - Gisela Nogales-Gadea
- Neuromuscular and Neuropediatric Research Group, Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol, Campus Can Ruti, Universitat Autònoma de Barcelona, Badalona, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III, Madrid, Spain
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19
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Cumming SA, Jimenez-Moreno C, Okkersen K, Wenninger S, Daidj F, Hogarth F, Littleford R, Gorman G, Bassez G, Schoser B, Lochmüller H, van Engelen BGM, Monckton DG. Genetic determinants of disease severity in the myotonic dystrophy type 1 OPTIMISTIC cohort. Neurology 2019; 93:e995-e1009. [PMID: 31395669 PMCID: PMC6745735 DOI: 10.1212/wnl.0000000000008056] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Accepted: 04/10/2019] [Indexed: 01/11/2023] Open
Abstract
Objective To evaluate the role of genetic variation at the DMPK locus on symptomatic diversity in 250 adult, ambulant patients with myotonic dystrophy type 1 (DM1) recruited to the Observational Prolonged Trial in Myotonic Dystrophy Type 1 to Improve Quality of Life—Standards, a Target Identification Collaboration (OPTIMISTIC) clinical trial. Methods We used small pool PCR to correct age at sampling biases and estimate the progenitor allele CTG repeat length and somatic mutational dynamics, and AciI digests and repeat primed PCR to test for the presence of variant repeats. Results We confirmed disease severity is driven by progenitor allele length, is further modified by age, and, in some cases, sex, and that patients in whom the CTG repeat expands more rapidly in the soma develop symptoms earlier than predicted. We revealed a key role for variant repeats in reducing disease severity and quantified their role in delaying age at onset by approximately 13.2 years (95% confidence interval 5.7–20.7, 2-tailed t test t = −3.7, p = 0.0019). Conclusions Careful characterization of the DMPK CTG repeat to define progenitor allele length and presence of variant repeats has increased utility in understanding clinical variability in a trial cohort and provides a genetic route for defining disease-specific outcome measures, and the basis of treatment response and stratification in DM1 trials.
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Affiliation(s)
- Sarah A Cumming
- From the Institute of Molecular, Cell and Systems Biology (S.A.C., D.G.M.), University of Glasgow; Institute of Genetic Medicine (C.J.-M., H.L.) and Institute of Neurosciences (G.G.), Newcastle University, Newcastle upon Tyne, UK; Department of Neurology (K.O., B.G.M.v.E.), Donders Institute for Brain Cognition and Behaviour, Radboud University Medical Centre, Nijmegen, the Netherlands; Department of Neurology (S.W., B.S.), Friedrich-Baur-Institute, Ludwig-Maximilians-Universität München, Munich, Germany; Neuromuscular Reference Centre (F.D., G.B.), Assistance Publique-Hôpitaux de Paris, France; and Tayside Clinical Trials Unit (F.H., R.L.), The University of Dundee, UK
| | - Cecilia Jimenez-Moreno
- From the Institute of Molecular, Cell and Systems Biology (S.A.C., D.G.M.), University of Glasgow; Institute of Genetic Medicine (C.J.-M., H.L.) and Institute of Neurosciences (G.G.), Newcastle University, Newcastle upon Tyne, UK; Department of Neurology (K.O., B.G.M.v.E.), Donders Institute for Brain Cognition and Behaviour, Radboud University Medical Centre, Nijmegen, the Netherlands; Department of Neurology (S.W., B.S.), Friedrich-Baur-Institute, Ludwig-Maximilians-Universität München, Munich, Germany; Neuromuscular Reference Centre (F.D., G.B.), Assistance Publique-Hôpitaux de Paris, France; and Tayside Clinical Trials Unit (F.H., R.L.), The University of Dundee, UK
| | - Kees Okkersen
- From the Institute of Molecular, Cell and Systems Biology (S.A.C., D.G.M.), University of Glasgow; Institute of Genetic Medicine (C.J.-M., H.L.) and Institute of Neurosciences (G.G.), Newcastle University, Newcastle upon Tyne, UK; Department of Neurology (K.O., B.G.M.v.E.), Donders Institute for Brain Cognition and Behaviour, Radboud University Medical Centre, Nijmegen, the Netherlands; Department of Neurology (S.W., B.S.), Friedrich-Baur-Institute, Ludwig-Maximilians-Universität München, Munich, Germany; Neuromuscular Reference Centre (F.D., G.B.), Assistance Publique-Hôpitaux de Paris, France; and Tayside Clinical Trials Unit (F.H., R.L.), The University of Dundee, UK
| | - Stephan Wenninger
- From the Institute of Molecular, Cell and Systems Biology (S.A.C., D.G.M.), University of Glasgow; Institute of Genetic Medicine (C.J.-M., H.L.) and Institute of Neurosciences (G.G.), Newcastle University, Newcastle upon Tyne, UK; Department of Neurology (K.O., B.G.M.v.E.), Donders Institute for Brain Cognition and Behaviour, Radboud University Medical Centre, Nijmegen, the Netherlands; Department of Neurology (S.W., B.S.), Friedrich-Baur-Institute, Ludwig-Maximilians-Universität München, Munich, Germany; Neuromuscular Reference Centre (F.D., G.B.), Assistance Publique-Hôpitaux de Paris, France; and Tayside Clinical Trials Unit (F.H., R.L.), The University of Dundee, UK
| | - Ferroudja Daidj
- From the Institute of Molecular, Cell and Systems Biology (S.A.C., D.G.M.), University of Glasgow; Institute of Genetic Medicine (C.J.-M., H.L.) and Institute of Neurosciences (G.G.), Newcastle University, Newcastle upon Tyne, UK; Department of Neurology (K.O., B.G.M.v.E.), Donders Institute for Brain Cognition and Behaviour, Radboud University Medical Centre, Nijmegen, the Netherlands; Department of Neurology (S.W., B.S.), Friedrich-Baur-Institute, Ludwig-Maximilians-Universität München, Munich, Germany; Neuromuscular Reference Centre (F.D., G.B.), Assistance Publique-Hôpitaux de Paris, France; and Tayside Clinical Trials Unit (F.H., R.L.), The University of Dundee, UK
| | - Fiona Hogarth
- From the Institute of Molecular, Cell and Systems Biology (S.A.C., D.G.M.), University of Glasgow; Institute of Genetic Medicine (C.J.-M., H.L.) and Institute of Neurosciences (G.G.), Newcastle University, Newcastle upon Tyne, UK; Department of Neurology (K.O., B.G.M.v.E.), Donders Institute for Brain Cognition and Behaviour, Radboud University Medical Centre, Nijmegen, the Netherlands; Department of Neurology (S.W., B.S.), Friedrich-Baur-Institute, Ludwig-Maximilians-Universität München, Munich, Germany; Neuromuscular Reference Centre (F.D., G.B.), Assistance Publique-Hôpitaux de Paris, France; and Tayside Clinical Trials Unit (F.H., R.L.), The University of Dundee, UK
| | - Roberta Littleford
- From the Institute of Molecular, Cell and Systems Biology (S.A.C., D.G.M.), University of Glasgow; Institute of Genetic Medicine (C.J.-M., H.L.) and Institute of Neurosciences (G.G.), Newcastle University, Newcastle upon Tyne, UK; Department of Neurology (K.O., B.G.M.v.E.), Donders Institute for Brain Cognition and Behaviour, Radboud University Medical Centre, Nijmegen, the Netherlands; Department of Neurology (S.W., B.S.), Friedrich-Baur-Institute, Ludwig-Maximilians-Universität München, Munich, Germany; Neuromuscular Reference Centre (F.D., G.B.), Assistance Publique-Hôpitaux de Paris, France; and Tayside Clinical Trials Unit (F.H., R.L.), The University of Dundee, UK
| | - Gráinne Gorman
- From the Institute of Molecular, Cell and Systems Biology (S.A.C., D.G.M.), University of Glasgow; Institute of Genetic Medicine (C.J.-M., H.L.) and Institute of Neurosciences (G.G.), Newcastle University, Newcastle upon Tyne, UK; Department of Neurology (K.O., B.G.M.v.E.), Donders Institute for Brain Cognition and Behaviour, Radboud University Medical Centre, Nijmegen, the Netherlands; Department of Neurology (S.W., B.S.), Friedrich-Baur-Institute, Ludwig-Maximilians-Universität München, Munich, Germany; Neuromuscular Reference Centre (F.D., G.B.), Assistance Publique-Hôpitaux de Paris, France; and Tayside Clinical Trials Unit (F.H., R.L.), The University of Dundee, UK
| | - Guillaume Bassez
- From the Institute of Molecular, Cell and Systems Biology (S.A.C., D.G.M.), University of Glasgow; Institute of Genetic Medicine (C.J.-M., H.L.) and Institute of Neurosciences (G.G.), Newcastle University, Newcastle upon Tyne, UK; Department of Neurology (K.O., B.G.M.v.E.), Donders Institute for Brain Cognition and Behaviour, Radboud University Medical Centre, Nijmegen, the Netherlands; Department of Neurology (S.W., B.S.), Friedrich-Baur-Institute, Ludwig-Maximilians-Universität München, Munich, Germany; Neuromuscular Reference Centre (F.D., G.B.), Assistance Publique-Hôpitaux de Paris, France; and Tayside Clinical Trials Unit (F.H., R.L.), The University of Dundee, UK
| | - Benedikt Schoser
- From the Institute of Molecular, Cell and Systems Biology (S.A.C., D.G.M.), University of Glasgow; Institute of Genetic Medicine (C.J.-M., H.L.) and Institute of Neurosciences (G.G.), Newcastle University, Newcastle upon Tyne, UK; Department of Neurology (K.O., B.G.M.v.E.), Donders Institute for Brain Cognition and Behaviour, Radboud University Medical Centre, Nijmegen, the Netherlands; Department of Neurology (S.W., B.S.), Friedrich-Baur-Institute, Ludwig-Maximilians-Universität München, Munich, Germany; Neuromuscular Reference Centre (F.D., G.B.), Assistance Publique-Hôpitaux de Paris, France; and Tayside Clinical Trials Unit (F.H., R.L.), The University of Dundee, UK
| | - Hanns Lochmüller
- From the Institute of Molecular, Cell and Systems Biology (S.A.C., D.G.M.), University of Glasgow; Institute of Genetic Medicine (C.J.-M., H.L.) and Institute of Neurosciences (G.G.), Newcastle University, Newcastle upon Tyne, UK; Department of Neurology (K.O., B.G.M.v.E.), Donders Institute for Brain Cognition and Behaviour, Radboud University Medical Centre, Nijmegen, the Netherlands; Department of Neurology (S.W., B.S.), Friedrich-Baur-Institute, Ludwig-Maximilians-Universität München, Munich, Germany; Neuromuscular Reference Centre (F.D., G.B.), Assistance Publique-Hôpitaux de Paris, France; and Tayside Clinical Trials Unit (F.H., R.L.), The University of Dundee, UK
| | - Baziel G M van Engelen
- From the Institute of Molecular, Cell and Systems Biology (S.A.C., D.G.M.), University of Glasgow; Institute of Genetic Medicine (C.J.-M., H.L.) and Institute of Neurosciences (G.G.), Newcastle University, Newcastle upon Tyne, UK; Department of Neurology (K.O., B.G.M.v.E.), Donders Institute for Brain Cognition and Behaviour, Radboud University Medical Centre, Nijmegen, the Netherlands; Department of Neurology (S.W., B.S.), Friedrich-Baur-Institute, Ludwig-Maximilians-Universität München, Munich, Germany; Neuromuscular Reference Centre (F.D., G.B.), Assistance Publique-Hôpitaux de Paris, France; and Tayside Clinical Trials Unit (F.H., R.L.), The University of Dundee, UK
| | - Darren G Monckton
- From the Institute of Molecular, Cell and Systems Biology (S.A.C., D.G.M.), University of Glasgow; Institute of Genetic Medicine (C.J.-M., H.L.) and Institute of Neurosciences (G.G.), Newcastle University, Newcastle upon Tyne, UK; Department of Neurology (K.O., B.G.M.v.E.), Donders Institute for Brain Cognition and Behaviour, Radboud University Medical Centre, Nijmegen, the Netherlands; Department of Neurology (S.W., B.S.), Friedrich-Baur-Institute, Ludwig-Maximilians-Universität München, Munich, Germany; Neuromuscular Reference Centre (F.D., G.B.), Assistance Publique-Hôpitaux de Paris, France; and Tayside Clinical Trials Unit (F.H., R.L.), The University of Dundee, UK.
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20
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Légaré C, Overend G, Guay SP, Monckton DG, Mathieu J, Gagnon C, Bouchard L. DMPK gene DNA methylation levels are associated with muscular and respiratory profiles in DM1. NEUROLOGY-GENETICS 2019; 5:e338. [PMID: 31334355 PMCID: PMC6568328 DOI: 10.1212/nxg.0000000000000338] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 04/03/2019] [Accepted: 04/04/2019] [Indexed: 12/03/2022]
Abstract
Objective To assess the effects of dystrophia myotonica protein kinase (DMPK) DNA methylation (DNAme) epivariation on muscular and respiratory profiles in patients with myotonic dystrophy type 1 (DM1). Methods Phenotypes were assessed with standardized measures. Pyrosequencing of bisulfite-treated DNA was used to quantify DNAme levels in blood from 90 patients with DM1 (adult form). Modal CTG repeat length was assessed using small-pool PCR. The presence of Acil-sensitive variant repeats was also tested. Results DNAme levels upstream of the CTG expansion (exon and intron 11) were correlated with modal CTG repeat length (rs = −0.224, p = 0.040; rs = −0.317, p = 0.003; and rs = −0.241, p = 0.027), whereas correlations were observed with epivariations downstream of the CTG repeats (rs = 0.227; p = 0.037). The presence of a variant repeat was associated with higher DNAme levels at multiple CpG sites (up to 10% higher; p = 0.001). Stepwise multiple linear regression modeling showed that DNAme contributed significantly and independently to explain phenotypic variability in ankle dorsiflexor (3 CpGs: p = 0.001, 0.013, and 0.001), grip (p = 0.089), and pinch (p = 0.028) strengths and in forced vital capacity (2 CpGs: p = 0.002 and 0.021) and maximal inspiratory pressure (p = 0.012). Conclusions In addition to the CTG repeat length, DMPK epivariations independently explain phenotypic variability in DM1 and could thus improve prognostic accuracy for patients.
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Affiliation(s)
- Cécilia Légaré
- Department of Biochemistry (C.L., S.-P.G., L.B.), Université de Sherbrooke, Sherbrooke; ECOGENE-21 Biocluster (C.L., S.-P.G., L.B.), Chicoutimi, Québec, Canada; Groupe de Recherche interdisciplinaire sur les maladies neuromusculaires (C.L., J.M., C.G., L.B.), Saguenay, Canada; Institute of Molecular (G.O., D.G.M.), Cell and Systems Biology, University of Glasgow, United Kingdom; and Centre de Recherche Charles-Le-Moyne-Saguenay-Lac-StJean sur les innovations en santé (J.M., C.G.), Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Canada
| | - Gayle Overend
- Department of Biochemistry (C.L., S.-P.G., L.B.), Université de Sherbrooke, Sherbrooke; ECOGENE-21 Biocluster (C.L., S.-P.G., L.B.), Chicoutimi, Québec, Canada; Groupe de Recherche interdisciplinaire sur les maladies neuromusculaires (C.L., J.M., C.G., L.B.), Saguenay, Canada; Institute of Molecular (G.O., D.G.M.), Cell and Systems Biology, University of Glasgow, United Kingdom; and Centre de Recherche Charles-Le-Moyne-Saguenay-Lac-StJean sur les innovations en santé (J.M., C.G.), Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Canada
| | - Simon-Pierre Guay
- Department of Biochemistry (C.L., S.-P.G., L.B.), Université de Sherbrooke, Sherbrooke; ECOGENE-21 Biocluster (C.L., S.-P.G., L.B.), Chicoutimi, Québec, Canada; Groupe de Recherche interdisciplinaire sur les maladies neuromusculaires (C.L., J.M., C.G., L.B.), Saguenay, Canada; Institute of Molecular (G.O., D.G.M.), Cell and Systems Biology, University of Glasgow, United Kingdom; and Centre de Recherche Charles-Le-Moyne-Saguenay-Lac-StJean sur les innovations en santé (J.M., C.G.), Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Canada
| | - Darren G Monckton
- Department of Biochemistry (C.L., S.-P.G., L.B.), Université de Sherbrooke, Sherbrooke; ECOGENE-21 Biocluster (C.L., S.-P.G., L.B.), Chicoutimi, Québec, Canada; Groupe de Recherche interdisciplinaire sur les maladies neuromusculaires (C.L., J.M., C.G., L.B.), Saguenay, Canada; Institute of Molecular (G.O., D.G.M.), Cell and Systems Biology, University of Glasgow, United Kingdom; and Centre de Recherche Charles-Le-Moyne-Saguenay-Lac-StJean sur les innovations en santé (J.M., C.G.), Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Canada
| | - Jean Mathieu
- Department of Biochemistry (C.L., S.-P.G., L.B.), Université de Sherbrooke, Sherbrooke; ECOGENE-21 Biocluster (C.L., S.-P.G., L.B.), Chicoutimi, Québec, Canada; Groupe de Recherche interdisciplinaire sur les maladies neuromusculaires (C.L., J.M., C.G., L.B.), Saguenay, Canada; Institute of Molecular (G.O., D.G.M.), Cell and Systems Biology, University of Glasgow, United Kingdom; and Centre de Recherche Charles-Le-Moyne-Saguenay-Lac-StJean sur les innovations en santé (J.M., C.G.), Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Canada
| | - Cynthia Gagnon
- Department of Biochemistry (C.L., S.-P.G., L.B.), Université de Sherbrooke, Sherbrooke; ECOGENE-21 Biocluster (C.L., S.-P.G., L.B.), Chicoutimi, Québec, Canada; Groupe de Recherche interdisciplinaire sur les maladies neuromusculaires (C.L., J.M., C.G., L.B.), Saguenay, Canada; Institute of Molecular (G.O., D.G.M.), Cell and Systems Biology, University of Glasgow, United Kingdom; and Centre de Recherche Charles-Le-Moyne-Saguenay-Lac-StJean sur les innovations en santé (J.M., C.G.), Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Canada
| | - Luigi Bouchard
- Department of Biochemistry (C.L., S.-P.G., L.B.), Université de Sherbrooke, Sherbrooke; ECOGENE-21 Biocluster (C.L., S.-P.G., L.B.), Chicoutimi, Québec, Canada; Groupe de Recherche interdisciplinaire sur les maladies neuromusculaires (C.L., J.M., C.G., L.B.), Saguenay, Canada; Institute of Molecular (G.O., D.G.M.), Cell and Systems Biology, University of Glasgow, United Kingdom; and Centre de Recherche Charles-Le-Moyne-Saguenay-Lac-StJean sur les innovations en santé (J.M., C.G.), Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Canada
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21
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Pešović J, Perić S, Brkušanin M, Brajušković G, Rakočević-Stojanović V, Savić-Pavićević D. Repeat Interruptions Modify Age at Onset in Myotonic Dystrophy Type 1 by Stabilizing DMPK Expansions in Somatic Cells. Front Genet 2018; 9:601. [PMID: 30546383 PMCID: PMC6278776 DOI: 10.3389/fgene.2018.00601] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Accepted: 11/15/2018] [Indexed: 12/19/2022] Open
Abstract
CTG expansions in DMPK gene, causing myotonic dystrophy type 1 (DM1), are characterized by pronounced somatic instability. A large proportion of variability of somatic instability is explained by expansion size and patient's age at sampling, while individual-specific differences are attributed to additional factors. The age at onset is extremely variable in DM1, and inversely correlates with the expansion size and individual-specific differences in somatic instability. Three to five percent of DM1 patients carry repeat interruptions and some appear with later age at onset than expected for corresponding expansion size. Herein, we characterized somatic instability of interrupted DMPK expansions and the effect on age at onset in our previously described patients. Repeat-primed PCR showed stable structures of different types and patterns of repeat interruptions in blood cells over time and buccal cells. Single-molecule small-pool PCR quantification of somatic instability and mathematical modeling showed that interrupted expansions were characterized by lower level of somatic instability accompanied by slower progression over time. Mathematical modeling demonstrated that individual-specific differences in somatic instability had greater influence on age at onset in patients with interrupted expansions. Therefore, repeat interruptions have clinical importance for disease course in DM1 patients due to stabilizing effect on DMPK expansions in somatic cells.
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Affiliation(s)
- Jovan Pešović
- Center for Human Molecular Genetics, Faculty of Biology, University of Belgrade, Belgrade, Serbia
| | - Stojan Perić
- School of Medicine, University of Belgrade, Belgrade, Serbia.,Neurology Clinic, Clinical Center of Serbia, Belgrade, Serbia
| | - Miloš Brkušanin
- Center for Human Molecular Genetics, Faculty of Biology, University of Belgrade, Belgrade, Serbia
| | - Goran Brajušković
- Center for Human Molecular Genetics, Faculty of Biology, University of Belgrade, Belgrade, Serbia
| | - Vidosava Rakočević-Stojanović
- School of Medicine, University of Belgrade, Belgrade, Serbia.,Neurology Clinic, Clinical Center of Serbia, Belgrade, Serbia
| | - Dušanka Savić-Pavićević
- Center for Human Molecular Genetics, Faculty of Biology, University of Belgrade, Belgrade, Serbia
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22
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Cumming SA, Hamilton MJ, Robb Y, Gregory H, McWilliam C, Cooper A, Adam B, McGhie J, Hamilton G, Herzyk P, Tschannen MR, Worthey E, Petty R, Ballantyne B, Warner J, Farrugia ME, Longman C, Monckton DG. De novo repeat interruptions are associated with reduced somatic instability and mild or absent clinical features in myotonic dystrophy type 1. Eur J Hum Genet 2018; 26:1635-1647. [PMID: 29967337 PMCID: PMC6189127 DOI: 10.1038/s41431-018-0156-9] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Revised: 03/23/2018] [Accepted: 03/30/2018] [Indexed: 01/10/2023] Open
Abstract
Myotonic dystrophy type 1 (DM1) is a multisystem disorder, caused by expansion of a CTG trinucleotide repeat in the 3'-untranslated region of the DMPK gene. The repeat expansion is somatically unstable and tends to increase in length with time, contributing to disease progression. In some individuals, the repeat array is interrupted by variant repeats such as CCG and CGG, stabilising the expansion and often leading to milder symptoms. We have characterised three families, each including one person with variant repeats that had arisen de novo on paternal transmission of the repeat expansion. Two individuals were identified for screening due to an unusual result in the laboratory diagnostic test, and the third due to exceptionally mild symptoms. The presence of variant repeats in all three expanded alleles was confirmed by restriction digestion of small pool PCR products, and allele structures were determined by PacBio sequencing. Each was different, but all contained CCG repeats close to the 3'-end of the repeat expansion. All other family members had inherited pure CTG repeats. The variant repeat-containing alleles were more stable in the blood than pure alleles of similar length, which may in part account for the mild symptoms observed in all three individuals. This emphasises the importance of somatic instability as a disease mechanism in DM1. Further, since patients with variant repeats may have unusually mild symptoms, identification of these individuals has important implications for genetic counselling and for patient stratification in DM1 clinical trials.
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Affiliation(s)
- Sarah A Cumming
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Mark J Hamilton
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK.
- West of Scotland Clinical Genetics Service, Queen Elizabeth University Hospital, Glasgow, G51 4TF, UK.
| | - Yvonne Robb
- Clinical Genetics Service, Western General Hospital, Edinburgh, EH4 2XU, UK
| | - Helen Gregory
- Department of Clinical Genetics, Aberdeen Royal Hospital, Aberdeen, AB25 2ZA, UK
| | | | - Anneli Cooper
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Berit Adam
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Josephine McGhie
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Graham Hamilton
- Glasgow Polyomics, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G61 1QH, UK
| | - Pawel Herzyk
- Glasgow Polyomics, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G61 1QH, UK
| | - Michael R Tschannen
- Human and Molecular Genetics Center, Medical College Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI, 53226, USA
| | - Elizabeth Worthey
- Human and Molecular Genetics Center, Medical College Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI, 53226, USA
- Hudson Alpha Institute for Biotechnology, 601 Genome Way, NW, Huntsville, AL, 35806, USA
| | - Richard Petty
- Department of Neurology, Institute of Neurological Sciences, Queen Elizabeth University Hospital, Glasgow, G51 4TF, UK
| | - Bob Ballantyne
- West of Scotland Clinical Genetics Service, Queen Elizabeth University Hospital, Glasgow, G51 4TF, UK
| | - Jon Warner
- Molecular Genetics Service, Molecular Medicine Centre, Western General Hospital, Crewe Road, Edinburgh, EH4 2XU, UK
| | - Maria Elena Farrugia
- Department of Neurology, Institute of Neurological Sciences, Queen Elizabeth University Hospital, Glasgow, G51 4TF, UK
| | - Cheryl Longman
- West of Scotland Clinical Genetics Service, Queen Elizabeth University Hospital, Glasgow, G51 4TF, UK
| | - Darren G Monckton
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
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23
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Activation of the interferon type I response rather than autophagy contributes to myogenesis inhibition in congenital DM1 myoblasts. Cell Death Dis 2018; 9:1071. [PMID: 30341284 PMCID: PMC6195593 DOI: 10.1038/s41419-018-1080-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Revised: 08/21/2018] [Accepted: 08/22/2018] [Indexed: 12/16/2022]
Abstract
Congenital myotonic dystrophy type 1 (CDM1) is characterized by severe symptoms that affect patients from birth, with 40% mortality in the neonatal period and impaired skeletal muscle development. In this paper, we examined the relationship between autophagy and abnormal myogenic differentiation of CDM1 myoblasts. We investigated these pathological features at both ultrastructural and molecular levels, utilizing two CDM1 foetal myoblasts, CDM13 and CDM15, with 1800 and 3200 repeats, respectively. The congenital nature of these CDM1 myoblasts was confirmed by the high methylation level at the DMPK locus. Our results indicated that abnormal autophagy was independent of myogenic differentiation, as CDM13 myoblasts differentiated as well as control myoblasts but underwent autophagy like CDM15, displaying impaired differentiation. miRNA expression profiles revealed that CDM15 myoblasts failed to upregulate the complex network of myo-miRNAs under MYOD and MEF2A control, while this network was upregulated in CDM13 myoblasts. Interestingly, the abnormal differentiation of CDM15 myoblasts was associated with cellular stress accompanied by the induction of the interferon type 1 pathway (innate immune response). Indeed, inhibition of the interferon (IFN) type I pathway restores myogenic differentiation of CDM15 myoblasts, suggesting that the inappropriate activation of the innate immune response might contribute to impaired myogenic differentiation and severe muscle symptoms observed in some CDM1 patients. These findings open up the possibility of new therapeutic approaches to treat CDM1.
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Tomé S, Dandelot E, Dogan C, Bertrand A, Geneviève D, Péréon Y, Simon M, Bonnefont JP, Bassez G, Gourdon G. Unusual association of a unique CAG interruption in 5' of DM1 CTG repeats with intergenerational contractions and low somatic mosaicism. Hum Mutat 2018; 39:970-982. [PMID: 29664219 DOI: 10.1002/humu.23531] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 03/23/2018] [Accepted: 04/10/2018] [Indexed: 11/11/2022]
Abstract
Myotonic dystrophy type 1 (DM1) is a dominant multisystemic disorder associated with high variability of symptoms and anticipation. DM1 is caused by an unstable CTG repeat expansion that usually increases in successive generations and tissues. DM1 family pedigrees have shown that ∼90% and 10% of transmissions result in expansions and contractions of the CTG repeat, respectively. To date, the mechanisms of CTG repeat contraction remain poorly documented in DM1. In this report, we identified two new DM1 families with apparent contractions and no worsening of DM1 symptoms in two and three successive maternal transmissions. A new and unique CAG interruption was found in 5' of the CTG expansion in one family, whereas multiple 5' CCG interruptions were detected in the second family. We showed that these interruptions are associated with maternal intergenerational contractions and low somatic mosaicism in blood. By specific triplet-prime PCR, we observed that CTG repeat changes (contractions/expansions) occur preferentially in 3' of the interruptions for both families.
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Affiliation(s)
- Stéphanie Tomé
- Laboratory CTGDM, Inserm UMR1163, Paris, France; Institut Imagine, Université Paris-Descartes-Sorbonne Paris-Cité, Paris, France
| | - Elodie Dandelot
- Laboratory CTGDM, Inserm UMR1163, Paris, France; Institut Imagine, Université Paris-Descartes-Sorbonne Paris-Cité, Paris, France
| | - Céline Dogan
- Neuromuscular Reference Center, AP-HP, Hôpital Pitié-Salpêtrière, F-75013, Paris, France
| | - Alexis Bertrand
- Laboratory CTGDM, Inserm UMR1163, Paris, France; Institut Imagine, Université Paris-Descartes-Sorbonne Paris-Cité, Paris, France
| | - David Geneviève
- Molecular Genetic Laboratory, Necker Hospital, Paris, France.,Département de Génétique Médicale, Maladies Rares et Médecine Personnalisée, CHU Montpellier, Université Montpellier, Montpellier, France
| | - Yann Péréon
- Centre for Neuromuscular Diseases, Hôtel-Dieu Hospital, Nantes, France
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- Pauline Arnaud: Department of genetic, Bichat Hospital, Paris, France, Raphaële Chasserieau: Centre for Neuromuscular Diseases, Hôtel-Dieu Hospital, Nantes, France, Pascal Cintas: Neuromuscular Reference Center, Purpan Hospital, Toulouse, France, Ana-maria Cobo Esteban: Neuromuscular Reference Center, Marin Hospital, Hendaye, France, Marie-Carmen Cruz: Neuromuscular Reference Center, Purpan Hospital, Toulouse, France, Dalil Hamroun: Centre Hospitalo-Universitaire de Montpellier, Montpellier, France, Armelle Magot: Neuromuscular Reference Center, Hôtel-Dieu Hospital, Nantes, France, Alexandra Nadaj-Pakleza Neuromuscular Reference Center, Larrey Hospital, Angers, France, Anne-catherine Aube-Gauthier Neuromuscular Reference Center, Larrey Hospital, Angers, France, Andoni Urtizberea: Neuromuscular Reference Center, Marin Hospital, Hendaye, France
| | - Marie Simon
- Molecular Genetic Laboratory, Necker Hospital, Paris, France
| | | | - Guillaume Bassez
- Sorbonne Université, Inserm, UMRS974, Neuromuscular Reference center, AP-HP, Hôpital Pitié-Salpêtrière, F-75013, Paris, France
| | - Geneviève Gourdon
- Laboratory CTGDM, Inserm UMR1163, Paris, France; Institut Imagine, Université Paris-Descartes-Sorbonne Paris-Cité, Paris, France
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Santoro M, Fontana L, Maiorca F, Centofanti F, Massa R, Silvestri G, Novelli G, Botta A. Expanded [CCTG]n repetitions are not associated with abnormal methylation at the CNBP locus in myotonic dystrophy type 2 (DM2) patients. Biochim Biophys Acta Mol Basis Dis 2018; 1864:917-924. [DOI: 10.1016/j.bbadis.2017.12.037] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Revised: 12/21/2017] [Accepted: 12/28/2017] [Indexed: 01/10/2023]
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Nakamori M, Hamanaka K, Thomas JD, Wang ET, Hayashi YK, Takahashi MP, Swanson MS, Nishino I, Mochizuki H. Aberrant Myokine Signaling in Congenital Myotonic Dystrophy. Cell Rep 2017; 21:1240-1252. [PMID: 29091763 PMCID: PMC5689469 DOI: 10.1016/j.celrep.2017.10.018] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Revised: 09/02/2017] [Accepted: 10/04/2017] [Indexed: 02/07/2023] Open
Abstract
Myotonic dystrophy types 1 (DM1) and 2 (DM2) are dominantly inherited neuromuscular disorders caused by a toxic gain of function of expanded CUG and CCUG repeats, respectively. Although both disorders are clinically similar, congenital myotonic dystrophy (CDM), a severe DM form, is found only in DM1. CDM is also characterized by muscle fiber immaturity not observed in adult DM, suggesting specific pathological mechanisms. Here, we revealed upregulation of the interleukin-6 (IL-6) myokine signaling pathway in CDM muscles. We also found a correlation between muscle immaturity and not only IL-6 expression but also expanded CTG repeat length and CpG methylation status upstream of the repeats. Aberrant CpG methylation was associated with transcriptional dysregulation at the repeat locus, increasing the toxic RNA burden that upregulates IL-6. Because the IL-6 pathway is involved in myocyte maturation and muscle atrophy, our results indicate that enhanced RNA toxicity contributes to severe CDM phenotypes through aberrant IL-6 signaling.
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Affiliation(s)
- Masayuki Nakamori
- Department of Neurology, Osaka University Graduate School of Medicine, Suita, Osaka 565-0871, Japan.
| | - Kohei Hamanaka
- Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Kodaira, Tokyo 187-8502, Japan
| | - James D Thomas
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, College of Medicine, Gainesville, FL 32610, USA
| | - Eric T Wang
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, College of Medicine, Gainesville, FL 32610, USA
| | - Yukiko K Hayashi
- Department of Pathophysiology, Tokyo Medical University, Shinjuku, Tokyo 160-0022, Japan
| | - Masanori P Takahashi
- Department of Neurology, Osaka University Graduate School of Medicine, Suita, Osaka 565-0871, Japan; Department of Functional Diagnostic Science, Osaka University Graduate School of Medicine, Suita, Osaka 565-0871, Japan
| | - Maurice S Swanson
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, College of Medicine, Gainesville, FL 32610, USA
| | - Ichizo Nishino
- Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Kodaira, Tokyo 187-8502, Japan
| | - Hideki Mochizuki
- Department of Neurology, Osaka University Graduate School of Medicine, Suita, Osaka 565-0871, Japan
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Identification and characterization of 5' CCG interruptions in complex DMPK expanded alleles. Eur J Hum Genet 2016; 25:257-261. [PMID: 27876818 DOI: 10.1038/ejhg.2016.148] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Revised: 09/05/2016] [Accepted: 10/07/2016] [Indexed: 12/16/2022] Open
Abstract
Myotonic dystrophy type 1 is a multisystemic autosomal dominant disorder caused by the expansion of (CTG) n triplets in the 3'UTR of the DMPK gene, on chromosome 19q13.3. In the last years, few DM1 patients with different patterns of CCG/CTC interruptions at the 3' end of the DMPK expanded tract have been described. However, the role of these interruptions in DM1 pathogenesis is still unclear. To study the frequency, stability and the structure of DMPK variant expanded alleles in the Italian population, we have re-evaluated 254 Italian DM1 patients using triplet-primed PCR (TP-PCR), at both the 3' and 5' ends of the CTG expansion. In addition, three DM1 families were also investigated in order to analyze the intergenerational stability of the interrupted DMPK alleles. Fourteen DM1 patients showed a TP-PCR electrophoretic profile indicating CCG/CTC interruptions within the CTG expansion. Interestingly, interruptions have been detected and, for the first time, sequenced at the 5' end of the CTG array. Analysis of five intergenerational transmissions revealed a substantial intrafamilial stability of the DM1 mutation among relatives. Our results support the hypothesis that CCG/CTC interruptions within the DMPK expanded alleles have a stabilizing effect on the mutational dynamics and can modulate the severity of symptoms in DM1 patients.
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