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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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