| Title: |
TTN:c.12478del in proximal I-band of titin represents a common molecular cause of dilated cardiomyopathy in Slovenian patients |
| Authors: |
Nina Vodnjov, Andraž Cerar, Aleš Maver, Borut Peterlin, Karin Writzl |
| Source: |
Orphanet Journal of Rare Diseases, Vol 20, Iss 1, Pp 1-9 (2025) |
| Publisher Information: |
BMC, 2025. |
| Publication Year: |
2025 |
| Collection: |
LCC:Medicine |
| Subject Terms: |
Titin, TTNtv, I-band, TTN:c.12478del, Dilated cardiomyopathy, DCM, Medicine |
| More Details: |
Abstract Background Titin truncating variants (TTNtv-s) are the most common genetic cause of dilated cardiomyopathy (DCM). Only rare TTNtv-s in the constitutively expressed exons of the A-band of the protein titin are associated with DCM according to the guidelines, however, studies in large cohorts of patients with DCM suggest that the region where TTNtv-s are associated with DCM is wider, extending at least into the I-band. The aim of this study was to describe the molecular pathology of TTNtv-s in Slovenian patients with cardiomyopathy and to clinically characterise the most recurrent TTNtv. Results We collected all TTNtv-s identified in patients with cardiomyopathy using next-generation sequencing genetic testing between 2010 and July 2024, resulting in 42 unique variants identified in 54 patients. The TTN:c.12478del variant, affecting not the A-band but the proximal I-band, specifically the cardiac-specific N2Bus region, was found to be the most recurrent variant, present in seven (11.6%) probands with DCM. Genetic characterisation revealed a probable founder origin of the variant. Clinical characterisation of these probands revealed a phenotype consistent with DCM and severely reduced left ventricular ejection fraction in all probands. Three (43%) of the probands had atrial fibrillation and/or non-sustained ventricular tachycardia. Based on literature reports and evidence supporting the pathogenicity of the TTN:c.12478del variant affecting the proximal I-band, we classified all rare TTNtv-s in constitutively expressed exons of the I-band as (likely) pathogenic. Therefore, 33 (78.6%) TTNtv-s were classified as (likely) pathogenic (13 in the I-band, affecting 19 probands and 20 in the A-band affecting 25 probands), meaning that TTNtv-s were identified in 44 genotype-positive Slovenian probands with DCM, explaining 73.3% of the molecular pathology of DCM. Conclusion We report an almost threefold higher diagnostic yield of TTNtv-s in probands with DCM compared to previously reported findings in cohorts of patients with DCM from other populations. We also highlight the need for screening for rare TTNtv-s in the constitutively expressed exons of the I-band and for TTN:c.12478del in patients with DCM in this geographical region. |
| Document Type: |
article |
| File Description: |
electronic resource |
| Language: |
English |
| ISSN: |
1750-1172 |
| Relation: |
https://doaj.org/toc/1750-1172 |
| DOI: |
10.1186/s13023-025-03613-7 |
| Access URL: |
https://doaj.org/article/12ad3d5bb09541daa65205fccb4869a6 |
| Accession Number: |
edsdoj.12ad3d5bb09541daa65205fccb4869a6 |
| Database: |
Directory of Open Access Journals |
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