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Audet S, Triassi V, Gelinas M, Legault-Cadieux N, Ferraro V, Duquette A, Tetreault M. Integration of multi-omics technologies for molecular diagnosis in ataxia patients. Front Genet 2024; 14:1304711. [PMID: 38239855 PMCID: PMC10794629 DOI: 10.3389/fgene.2023.1304711] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Accepted: 11/27/2023] [Indexed: 01/22/2024] Open
Abstract
Background: Episodic ataxias are rare neurological disorders characterized by recurring episodes of imbalance and coordination difficulties. Obtaining definitive molecular diagnoses poses challenges, as clinical presentation is highly heterogeneous, and literature on the underlying genetics is limited. While the advent of high-throughput sequencing technologies has significantly contributed to Mendelian disorders genetics, interpretation of variants of uncertain significance and other limitations inherent to individual methods still leaves many patients undiagnosed. This study aimed to investigate the utility of multi-omics for the identification and validation of molecular candidates in a cohort of complex cases of ataxia with episodic presentation. Methods: Eight patients lacking molecular diagnosis despite extensive clinical examination were recruited following standard genetic testing. Whole genome and RNA sequencing were performed on samples isolated from peripheral blood mononuclear cells. Integration of expression and splicing data facilitated genomic variants prioritization. Subsequently, long-read sequencing played a crucial role in the validation of those candidate variants. Results: Whole genome sequencing uncovered pathogenic variants in four genes (SPG7, ATXN2, ELOVL4, PMPCB). A missense and a nonsense variant, both previously reported as likely pathogenic, configured in trans in individual #1 (SPG7: c.2228T>C/p.I743T, c.1861C>T/p.Q621*). An ATXN2 microsatellite expansion (CAG32) in another late-onset case. In two separate individuals, intronic variants near splice sites (ELOVL4: c.541 + 5G>A; PMPCB: c.1154 + 5G>C) were predicted to induce loss-of-function splicing, but had never been reported as disease-causing. Long-read sequencing confirmed the compound heterozygous variants configuration, repeat expansion length, as well as splicing landscape for those pathogenic variants. A potential genetic modifier of the ATXN2 expansion was discovered in ZFYVE26 (c.3022C>T/p.R1008*). Conclusion: Despite failure to identify pathogenic variants through clinical genetic testing, the multi-omics approach enabled the molecular diagnosis in 50% of patients, also giving valuable insights for variant prioritization in remaining cases. The findings demonstrate the value of long-read sequencing for the validation of candidate variants in various scenarios. Our study demonstrates the effectiveness of leveraging complementary omics technologies to unravel the underlying genetics in patients with unresolved rare diseases such as ataxia. Molecular diagnoses not only hold significant promise in improving patient care management, but also alleviates the burden of diagnostic odysseys, more broadly enhancing quality of life.
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Affiliation(s)
- Sebastien Audet
- University of Montreal Hospital Research Center (CRCHUM), Montreal, QC, Canada
- Department of Neurosciences, University of Montreal, Montreal, QC, Canada
| | - Valerie Triassi
- University of Montreal Hospital Research Center (CRCHUM), Montreal, QC, Canada
| | - Myriam Gelinas
- Department of Medicine, University of Montreal Hospital Centre (CHUM), Montreal, QC, Canada
| | - Nab Legault-Cadieux
- University of Montreal Hospital Research Center (CRCHUM), Montreal, QC, Canada
- Department of Neurosciences, University of Montreal, Montreal, QC, Canada
| | - Vincent Ferraro
- Department of Medicine, University of Montreal Hospital Centre (CHUM), Montreal, QC, Canada
| | - Antoine Duquette
- University of Montreal Hospital Research Center (CRCHUM), Montreal, QC, Canada
- Department of Neurosciences, University of Montreal, Montreal, QC, Canada
- Neurology Service, Department of Medicine, André-Barbeau Movement Disorders Unit, University of Montreal Hospital (CHUM), Montreal, QC, Canada
- Genetic Service, Department of Medicine, University of Montreal Hospital (CHUM), Montreal, QC, Canada
| | - Martine Tetreault
- University of Montreal Hospital Research Center (CRCHUM), Montreal, QC, Canada
- Department of Neurosciences, University of Montreal, Montreal, QC, Canada
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Bermejo-Guerrero L, Arteche-López A, de Fuenmayor Fernández de la Hoz C, Hernández-Laín A, Martín MA, Domínguez-González C. A novel MLIP truncating variant in an 80-year-old patient with late-onset progressive weakness. Brain 2022; 145:e99-e102. [PMID: 35915960 DOI: 10.1093/brain/awac286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Accepted: 07/24/2022] [Indexed: 11/12/2022] Open
Affiliation(s)
- Laura Bermejo-Guerrero
- Neuromuscular Unit, Department of Neurology, 12 de Octubre University Hospital, 28041, Madrid, Spain
| | - Ana Arteche-López
- Department of Genetics, 12 de Octubre University Hospital, 28041, Madrid, Spain.,UDISGEN (Unidad de Dismorfología y Genética), 12 de Octubre University Hospital, 28041, Madrid, Spain
| | | | - Aurelio Hernández-Laín
- Neuropathology Unit, Department of Pathology, 12 de Octubre University Hospital, 28041, Madrid, Spain.,imas12 Research Institute, 12 de Octubre University Hospital, 28041, Madrid, Spain
| | - Miguel A Martín
- imas12 Research Institute, 12 de Octubre University Hospital, 28041, Madrid, Spain.,Mitochondrial Disorders Laboratory, Clinical Biochemistry Department. 12 de Octubre University Hospital, 28041, Madrid, Spain.,Biomedical Network Research Center on Rare Diseases (CIBERER), 28029, Madrid, Spain
| | - Cristina Domínguez-González
- Neuromuscular Unit, Department of Neurology, 12 de Octubre University Hospital, 28041, Madrid, Spain.,imas12 Research Institute, 12 de Octubre University Hospital, 28041, Madrid, Spain.,Biomedical Network Research Center on Rare Diseases (CIBERER), 28029, Madrid, Spain
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