1
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An Z, Jiang A, Chen J. Toward understanding the role of genomic repeat elements in neurodegenerative diseases. Neural Regen Res 2025; 20:646-659. [PMID: 38886931 DOI: 10.4103/nrr.nrr-d-23-01568] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Accepted: 03/02/2024] [Indexed: 06/20/2024] Open
Abstract
Neurodegenerative diseases cause great medical and economic burdens for both patients and society; however, the complex molecular mechanisms thereof are not yet well understood. With the development of high-coverage sequencing technology, researchers have started to notice that genomic repeat regions, previously neglected in search of disease culprits, are active contributors to multiple neurodegenerative diseases. In this review, we describe the association between repeat element variants and multiple degenerative diseases through genome-wide association studies and targeted sequencing. We discuss the identification of disease-relevant repeat element variants, further powered by the advancement of long-read sequencing technologies and their related tools, and summarize recent findings in the molecular mechanisms of repeat element variants in brain degeneration, such as those causing transcriptional silencing or RNA-mediated gain of toxic function. Furthermore, we describe how in silico predictions using innovative computational models, such as deep learning language models, could enhance and accelerate our understanding of the functional impact of repeat element variants. Finally, we discuss future directions to advance current findings for a better understanding of neurodegenerative diseases and the clinical applications of genomic repeat elements.
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Affiliation(s)
- Zhengyu An
- Institute of Science and Technology for Brain-Inspired Intelligence, Fudan University, Shanghai, China
| | - Aidi Jiang
- Institute of Science and Technology for Brain-Inspired Intelligence, Fudan University, Shanghai, China
| | - Jingqi Chen
- Institute of Science and Technology for Brain-Inspired Intelligence, Fudan University, Shanghai, China
- MOE Frontiers Center for Brain Science, Fudan University, Shanghai, China
- MOE Key Laboratory of Computational Neuroscience and Brain-Inspired Intelligence, Fudan University, Shanghai, China
- Zhangjiang Fudan International Innovation Center, Shanghai, China
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2
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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; 25:476-499. [PMID: 38467784 DOI: 10.1038/s41576-024-00696-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [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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3
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Shelton WJ, Zandpazandi S, Nix JS, Gokden M, Bauer M, Ryan KR, Wardell CP, Vaske OM, Rodriguez A. Long-read sequencing for brain tumors. Front Oncol 2024; 14:1395985. [PMID: 38915364 PMCID: PMC11194609 DOI: 10.3389/fonc.2024.1395985] [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: 03/05/2024] [Accepted: 05/27/2024] [Indexed: 06/26/2024] Open
Abstract
Brain tumors and genomics have a long-standing history given that glioblastoma was the first cancer studied by the cancer genome atlas. The numerous and continuous advances through the decades in sequencing technologies have aided in the advanced molecular characterization of brain tumors for diagnosis, prognosis, and treatment. Since the implementation of molecular biomarkers by the WHO CNS in 2016, the genomics of brain tumors has been integrated into diagnostic criteria. Long-read sequencing, also known as third generation sequencing, is an emerging technique that allows for the sequencing of longer DNA segments leading to improved detection of structural variants and epigenetics. These capabilities are opening a way for better characterization of brain tumors. Here, we present a comprehensive summary of the state of the art of third-generation sequencing in the application for brain tumor diagnosis, prognosis, and treatment. We discuss the advantages and potential new implementations of long-read sequencing into clinical paradigms for neuro-oncology patients.
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Affiliation(s)
- William J. Shelton
- Department of Neurosurgery, College of Medicine, University of Arkansas for Medical Sciences, Little Rock, AR, United States
| | - Sara Zandpazandi
- Department of Neurosurgery, Medical University of South Carolina, Charleston, SC, United States
| | - J Stephen Nix
- Department of Pathology, University of Arkansas for Medical Sciences, Little Rock, AR, United States
| | - Murat Gokden
- Department of Pathology, University of Arkansas for Medical Sciences, Little Rock, AR, United States
| | - Michael Bauer
- Department of Biomedical Informatics, University of Arkansas for Medical Sciences, Little Rock, AR, United States
| | - Katie Rose Ryan
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, AR, United States
| | - Christopher P. Wardell
- Department of Biomedical Informatics, University of Arkansas for Medical Sciences, Little Rock, AR, United States
| | - Olena Morozova Vaske
- Department of Molecular, Cell and Developmental Biology, University of California Santa Cruz, Santa Cruz, CA, United States
| | - Analiz Rodriguez
- Department of Neurosurgery, College of Medicine, University of Arkansas for Medical Sciences, Little Rock, AR, United States
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Scarano C, Veneruso I, De Simone RR, Di Bonito G, Secondino A, D’Argenio V. The Third-Generation Sequencing Challenge: Novel Insights for the Omic Sciences. Biomolecules 2024; 14:568. [PMID: 38785975 PMCID: PMC11117673 DOI: 10.3390/biom14050568] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2024] [Revised: 05/05/2024] [Accepted: 05/08/2024] [Indexed: 05/25/2024] Open
Abstract
The understanding of the human genome has been greatly improved by the advent of next-generation sequencing technologies (NGS). Despite the undeniable advantages responsible for their widespread diffusion, these methods have some constraints, mainly related to short read length and the need for PCR amplification. As a consequence, long-read sequencers, called third-generation sequencing (TGS), have been developed, promising to overcome NGS. Starting from the first prototype, TGS has progressively ameliorated its chemistries by improving both read length and base-calling accuracy, as well as simultaneously reducing the costs/base. Based on these premises, TGS is showing its potential in many fields, including the analysis of difficult-to-sequence genomic regions, structural variations detection, RNA expression profiling, DNA methylation study, and metagenomic analyses. Protocol standardization and the development of easy-to-use pipelines for data analysis will enhance TGS use, also opening the way for their routine applications in diagnostic contexts.
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Affiliation(s)
- Carmela Scarano
- Department of Molecular Medicine and Medical Biotechnologies, Federico II University, Via Sergio Pansini 5, 80131 Napoli, Italy
- CEINGE-Biotecnologie Avanzate Franco Salvatore, Via G. Salvatore 486, 80145 Napoli, Italy
| | - Iolanda Veneruso
- Department of Molecular Medicine and Medical Biotechnologies, Federico II University, Via Sergio Pansini 5, 80131 Napoli, Italy
- CEINGE-Biotecnologie Avanzate Franco Salvatore, Via G. Salvatore 486, 80145 Napoli, Italy
| | - Rosa Redenta De Simone
- Department of Molecular Medicine and Medical Biotechnologies, Federico II University, Via Sergio Pansini 5, 80131 Napoli, Italy
- CEINGE-Biotecnologie Avanzate Franco Salvatore, Via G. Salvatore 486, 80145 Napoli, Italy
| | - Gennaro Di Bonito
- Department of Molecular Medicine and Medical Biotechnologies, Federico II University, Via Sergio Pansini 5, 80131 Napoli, Italy
- CEINGE-Biotecnologie Avanzate Franco Salvatore, Via G. Salvatore 486, 80145 Napoli, Italy
| | - Angela Secondino
- Department of Molecular Medicine and Medical Biotechnologies, Federico II University, Via Sergio Pansini 5, 80131 Napoli, Italy
- CEINGE-Biotecnologie Avanzate Franco Salvatore, Via G. Salvatore 486, 80145 Napoli, Italy
| | - Valeria D’Argenio
- CEINGE-Biotecnologie Avanzate Franco Salvatore, Via G. Salvatore 486, 80145 Napoli, Italy
- Department of Human Sciences and Quality of Life Promotion, San Raffaele Open University, Via di Val Cannuta 247, 00166 Roma, Italy
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Uppuluri L, Shi CH, Varapula D, Young E, Ehrlich RL, Wang Y, Piazza D, Mell JC, Yip KY, Xiao M. A long-read sequencing strategy with overlapping linkers on adjacent fragments (OLAF-Seq) for targeted resequencing and enrichment. Sci Rep 2024; 14:5583. [PMID: 38448490 PMCID: PMC10917763 DOI: 10.1038/s41598-024-56402-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Accepted: 03/06/2024] [Indexed: 03/08/2024] Open
Abstract
In this report, we present OLAF-Seq, a novel strategy to construct a long-read sequencing library such that adjacent fragments are linked with end-terminal duplications. We use the CRISPR-Cas9 nickase enzyme and a pool of multiple sgRNAs to perform non-random fragmentation of targeted long DNA molecules (> 300kb) into smaller library-sized fragments (about 20 kbp) in a manner so as to retain physical linkage information (up to 1000 bp) between adjacent fragments. DNA molecules targeted for fragmentation are preferentially ligated with adaptors for sequencing, so this method can enrich targeted regions while taking advantage of the long-read sequencing platforms. This enables the sequencing of target regions with significantly lower total coverage, and the genome sequence within linker regions provides information for assembly and phasing. We demonstrated the validity and efficacy of the method first using phage and then by sequencing a panel of 100 full-length cancer-related genes (including both exons and introns) in the human genome. When the designed linkers contained heterozygous genetic variants, long haplotypes could be established. This sequencing strategy can be readily applied in both PacBio and Oxford Nanopore platforms for both long and short genes with an easy protocol. This economically viable approach is useful for targeted enrichment of hundreds of target genomic regions and where long no-gap contigs need deep sequencing.
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Affiliation(s)
- Lahari Uppuluri
- School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, PA, 19104, USA
| | - Christina Huan Shi
- Cancer Genome and Epigenetics Program, NCI-Designated Cancer Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, 92037, USA
| | - Dharma Varapula
- School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, PA, 19104, USA
| | - Eleanor Young
- School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, PA, 19104, USA
| | - Rachel L Ehrlich
- Department of Microbiology and Immunology, College of Medicine, Drexel University, Philadelphia, PA, 19104, USA
- Center for Genomic Sciences, Institute of Molecular Medicine and Infectious Disease, Drexel University, Philadelphia, PA, 19104, USA
| | - Yilin Wang
- School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, PA, 19104, USA
| | - Danielle Piazza
- Department of Microbiology and Immunology, College of Medicine, Drexel University, Philadelphia, PA, 19104, USA
- Center for Genomic Sciences, Institute of Molecular Medicine and Infectious Disease, Drexel University, Philadelphia, PA, 19104, USA
| | - Joshua Chang Mell
- Department of Microbiology and Immunology, College of Medicine, Drexel University, Philadelphia, PA, 19104, USA
- Center for Genomic Sciences, Institute of Molecular Medicine and Infectious Disease, Drexel University, Philadelphia, PA, 19104, USA
| | - Kevin Y Yip
- Cancer Genome and Epigenetics Program, NCI-Designated Cancer Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, 92037, USA
| | - Ming Xiao
- School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, PA, 19104, USA.
- Center for Genomic Sciences, Institute of Molecular Medicine and Infectious Disease, Drexel University, Philadelphia, PA, 19104, USA.
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Olivucci G, Iovino E, Innella G, Turchetti D, Pippucci T, Magini P. Long read sequencing on its way to the routine diagnostics of genetic diseases. Front Genet 2024; 15:1374860. [PMID: 38510277 PMCID: PMC10951082 DOI: 10.3389/fgene.2024.1374860] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Accepted: 02/26/2024] [Indexed: 03/22/2024] Open
Abstract
The clinical application of technological progress in the identification of DNA alterations has always led to improvements of diagnostic yields in genetic medicine. At chromosome side, from cytogenetic techniques evaluating number and gross structural defects to genomic microarrays detecting cryptic copy number variants, and at molecular level, from Sanger method studying the nucleotide sequence of single genes to the high-throughput next-generation sequencing (NGS) technologies, resolution and sensitivity progressively increased expanding considerably the range of detectable DNA anomalies and alongside of Mendelian disorders with known genetic causes. However, particular genomic regions (i.e., repetitive and GC-rich sequences) are inefficiently analyzed by standard genetic tests, still relying on laborious, time-consuming and low-sensitive approaches (i.e., southern-blot for repeat expansion or long-PCR for genes with highly homologous pseudogenes), accounting for at least part of the patients with undiagnosed genetic disorders. Third generation sequencing, generating long reads with improved mappability, is more suitable for the detection of structural alterations and defects in hardly accessible genomic regions. Although recently implemented and not yet clinically available, long read sequencing (LRS) technologies have already shown their potential in genetic medicine research that might greatly impact on diagnostic yield and reporting times, through their translation to clinical settings. The main investigated LRS application concerns the identification of structural variants and repeat expansions, probably because techniques for their detection have not evolved as rapidly as those dedicated to single nucleotide variants (SNV) identification: gold standard analyses are karyotyping and microarrays for balanced and unbalanced chromosome rearrangements, respectively, and southern blot and repeat-primed PCR for the amplification and sizing of expanded alleles, impaired by limited resolution and sensitivity that have not been significantly improved by the advent of NGS. Nevertheless, more recently, with the increased accuracy provided by the latest product releases, LRS has been tested also for SNV detection, especially in genes with highly homologous pseudogenes and for haplotype reconstruction to assess the parental origin of alleles with de novo pathogenic variants. We provide a review of relevant recent scientific papers exploring LRS potential in the diagnosis of genetic diseases and its potential future applications in routine genetic testing.
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Affiliation(s)
- Giulia Olivucci
- IRCCS Azienda Ospedaliero-Universitaria di Bologna, Bologna, Italy
- Department of Surgical and Oncological Sciences, University of Palermo, Palermo, Italy
| | - Emanuela Iovino
- IRCCS Azienda Ospedaliero-Universitaria di Bologna, Bologna, Italy
| | - Giovanni Innella
- Department of Medical and Surgical Sciences (DIMEC), University of Bologna, Bologna, Italy
- Medical Genetics Unit, IRCCS Azienda Ospedaliero-Universitaria di Bologna, Bologna, Italy
| | - Daniela Turchetti
- Department of Medical and Surgical Sciences (DIMEC), University of Bologna, Bologna, Italy
- Medical Genetics Unit, IRCCS Azienda Ospedaliero-Universitaria di Bologna, Bologna, Italy
| | - Tommaso Pippucci
- IRCCS Azienda Ospedaliero-Universitaria di Bologna, Bologna, Italy
| | - Pamela Magini
- Medical Genetics Unit, IRCCS Azienda Ospedaliero-Universitaria di Bologna, Bologna, Italy
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7
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Sahın Vural G, Bolat H. Nanopore sequencing method for CTG18.1 expansion in TCF4 in late-onset Fuchs endothelial corneal dystrophy and a comparison of the structural features of cornea with first-degree relatives. Graefes Arch Clin Exp Ophthalmol 2024; 262:903-911. [PMID: 37747538 DOI: 10.1007/s00417-023-06243-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Revised: 09/12/2023] [Accepted: 09/15/2023] [Indexed: 09/26/2023] Open
Abstract
BACKGROUND To evaluate the relationship between the number of trinucleotide repeats (TNR) in late-onset Fuchs corneal endothelial dystrophy (FCED) and to compare the endothelial properties of FCED, first-degree relatives, and controls. METHODS Blood samples were collected from FCEDs to determine TNR number. The FCED patients, first-degree relatives, and controls were examined with specular microscopy for central corneal thickness (CCT), endothelial cell density (ECD), pleomorphism and polymegatism, and with corneal topography for specific indicators such as (i) displacement of thinnest point of cornea, (ii) loss of isopachs, (iii) focal posterior surface depression towards anterior chamber. RESULTS This study included 92 patients with FCED, 92 first-degree relatives, and 96 controls. CCT was thickest in FCEDs (558.0 μm) (p < 0.05) while there was no difference between relatives (533.0 μm) and controls (530.4 μm) (p = 0.845). ECD was decreased in both FCED (2069.2 mm2) and relatives (2171.4 mm2) than controls (2822.9 mm2) (p < 0.05 in both). The presence of pleomorphism and polymegatism was significant in patients with FCED (93.4% and 93.4%, respectively), relatives (86.9% and 86.04%, respectively), and controls (8.33% and 1.04%, respectively) (p < 0.05). Specific topographic indicators differed among the groups (p < 0.05). The mean repeat number of the FCED patients was 17.48 ± 4.54 (12-25) times. The TNR number of FCED cases correlated with the relative CCT (p < 0.05, R = 0.615) and cell density (p = 0.009, R = -0.499). CONCLUSIONS A strong association between the corneal endothelium in relatives and TNR number of FCEDs was defined. Relatives tended to have fewer corneal endothelial cells, even though they did not have clinical findings.
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Affiliation(s)
- Gozde Sahın Vural
- Department of Ophthalmology, Balıkesir University Medicine Faculty, Balıkesir, Turkey.
- Department of Ophthalmology, Balıkesir University Medicine Faculty Hospital, Balıkesir, Turkey.
| | - Hilmi Bolat
- Department of Genetics, Balıkesir University Medicine Faculty, Balıkesir, Turkey
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Yu SY, Xi YL, Xu FQ, Zhang J, Liu YS. Application of long read sequencing in rare diseases: The longer, the better? Eur J Med Genet 2023; 66:104871. [PMID: 38832911 DOI: 10.1016/j.ejmg.2023.104871] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2023] [Revised: 10/11/2023] [Accepted: 10/22/2023] [Indexed: 06/06/2024]
Abstract
Rare diseases encompass a diverse group of genetic disorders that affect a small proportion of the population. Identifying the underlying genetic causes of these conditions presents significant challenges due to their genetic heterogeneity and complexity. Conventional short-read sequencing (SRS) techniques have been widely used in diagnosing and investigating of rare diseases, with limitations due to the nature of short-read lengths. In recent years, long read sequencing (LRS) technologies have emerged as a valuable tool in overcoming these limitations. This minireview provides a concise overview of the applications of LRS in rare disease research and diagnosis, including the identification of disease-causing tandem repeat expansions, structural variations, and comprehensive analysis of pathogenic variants with LRS.
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Affiliation(s)
- Si-Yan Yu
- Department of Pediatric Laboratory, Affiliated Children's Hospital of Jiangnan University (Wuxi Children's Hospital), Wuxi, Jiangsu, China; The First School of Clinical Medicine, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Yu-Lin Xi
- Wuxi School of Medicine, Jiangnan University, Wuxi, Jiangsu, China
| | - Fu-Qiang Xu
- Department of Gynecology, Beijing Youan Hospital, Capital Medical University, Beijing, China
| | - Jian Zhang
- Department of Medical Laboratory, Affiliated Children's Hospital of Jiangnan University (Wuxi Children's Hospital), Wuxi, Jiangsu, China.
| | - Yan-Shan Liu
- Department of Pediatric Laboratory, Affiliated Children's Hospital of Jiangnan University (Wuxi Children's Hospital), Wuxi, Jiangsu, China; Wuxi School of Medicine, Jiangnan University, Wuxi, Jiangsu, China.
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9
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Goldman JS, Uhlmann WR, Naini AB, Klitzman RL, Marder KS. Genetic Testing of HTT Modifiers for Huntington's Disease: Considerations for Clinical Guidelines. Mov Disord 2023; 38:2151-2154. [PMID: 37975739 DOI: 10.1002/mds.29650] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Revised: 09/24/2023] [Accepted: 10/16/2023] [Indexed: 11/19/2023] Open
Affiliation(s)
- Jill S Goldman
- Department of Neurology, Columbia University Irving Medical Center, New York, New York, USA
| | - Wendy R Uhlmann
- Departments of Internal Medicine and Human Genetics, University of Michigan, Ann Arbor, Michigan, USA
| | - Ali B Naini
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, New York, USA
| | - Robert L Klitzman
- Department of Psychiatry, Columbia University Irving Medical Center, Mailman School of Public Health, Columbia University, New York, New York, USA
| | - Karen S Marder
- Department of Neurology, Columbia University Irving Medical Center, New York, New York, USA
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Johansson J, Lidéus S, Höijer I, Ameur A, Gudmundsson S, Annerén G, Bondeson ML, Wilbe M. A novel quantitative targeted analysis of X-chromosome inactivation (XCI) using nanopore sequencing. Sci Rep 2023; 13:12856. [PMID: 37553382 PMCID: PMC10409790 DOI: 10.1038/s41598-023-34413-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Accepted: 04/29/2023] [Indexed: 08/10/2023] Open
Abstract
X-chromosome inactivation (XCI) analyses often assist in diagnostics of X-linked traits, however accurate assessment remains challenging with current methods. We developed a novel strategy using amplification-free Cas9 enrichment and Oxford nanopore technologies sequencing called XCI-ONT, to investigate and rigorously quantify XCI in human androgen receptor gene (AR) and human X-linked retinitis pigmentosa 2 gene (RP2). XCI-ONT measures methylation over 116 CpGs in AR and 58 CpGs in RP2, and separate parental X-chromosomes without PCR bias. We show the usefulness of the XCI-ONT strategy over the PCR-based golden standard XCI technique that only investigates one or two CpGs per gene. The results highlight the limitations of using the golden standard technique when the XCI pattern is partially skewed and the advantages of XCI-ONT to rigorously quantify XCI. This study provides a universal XCI-method on DNA, which is highly valuable in clinical and research framework of X-linked traits.
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Affiliation(s)
- Josefin Johansson
- Department of Immunology, Genetics and Pathology, Science for Life Laboratory, Uppsala University, Husargatan 3, Box 815, SE-751 08, Uppsala, Sweden
| | - Sarah Lidéus
- Department of Immunology, Genetics and Pathology, Science for Life Laboratory, Uppsala University, Husargatan 3, Box 815, SE-751 08, Uppsala, Sweden
| | - Ida Höijer
- Department of Immunology, Genetics and Pathology, Science for Life Laboratory, Uppsala University, Husargatan 3, Box 815, SE-751 08, Uppsala, Sweden
| | - Adam Ameur
- Department of Immunology, Genetics and Pathology, Science for Life Laboratory, Uppsala University, Husargatan 3, Box 815, SE-751 08, Uppsala, Sweden
| | - Sanna Gudmundsson
- Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Division of Genetics and Genomics, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Göran Annerén
- Department of Immunology, Genetics and Pathology, Science for Life Laboratory, Uppsala University, Husargatan 3, Box 815, SE-751 08, Uppsala, Sweden
| | - Marie-Louise Bondeson
- Department of Immunology, Genetics and Pathology, Science for Life Laboratory, Uppsala University, Husargatan 3, Box 815, SE-751 08, Uppsala, Sweden
| | - Maria Wilbe
- Department of Immunology, Genetics and Pathology, Science for Life Laboratory, Uppsala University, Husargatan 3, Box 815, SE-751 08, Uppsala, Sweden.
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11
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Mastrorosa FK, Miller DE, Eichler EE. Applications of long-read sequencing to Mendelian genetics. Genome Med 2023; 15:42. [PMID: 37316925 DOI: 10.1186/s13073-023-01194-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Accepted: 05/18/2023] [Indexed: 06/16/2023] Open
Abstract
Advances in clinical genetic testing, including the introduction of exome sequencing, have uncovered the molecular etiology for many rare and previously unsolved genetic disorders, yet more than half of individuals with a suspected genetic disorder remain unsolved after complete clinical evaluation. A precise genetic diagnosis may guide clinical treatment plans, allow families to make informed care decisions, and permit individuals to participate in N-of-1 trials; thus, there is high interest in developing new tools and techniques to increase the solve rate. Long-read sequencing (LRS) is a promising technology for both increasing the solve rate and decreasing the amount of time required to make a precise genetic diagnosis. Here, we summarize current LRS technologies, give examples of how they have been used to evaluate complex genetic variation and identify missing variants, and discuss future clinical applications of LRS. As costs continue to decrease, LRS will find additional utility in the clinical space fundamentally changing how pathological variants are discovered and eventually acting as a single-data source that can be interrogated multiple times for clinical service.
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Affiliation(s)
| | - Danny E Miller
- Division of Genetic Medicine, Department of Pediatrics, University of Washington and Seattle Children's Hospital, Seattle, WA, 98195, USA
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, 98195, USA
- Brotman Baty Institute for Precision Medicine, University of Washington, Seattle, WA, 98195, USA
| | - Evan E Eichler
- Department of Genome Sciences, University of Washington School of Medicine, Seattle, WA, 98195, USA.
- Howard Hughes Medical Institute, University of Washington, Seattle, WA, 98195, USA.
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12
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Santiago JC, Westfall DH, Adams SV, Okuku F, Phipps W, Mullins JI. Variation within major internal repeats of KSHV in vivo. Virus Evol 2023; 9:vead034. [PMID: 37325087 PMCID: PMC10266750 DOI: 10.1093/ve/vead034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Revised: 05/09/2023] [Accepted: 05/18/2023] [Indexed: 06/17/2023] Open
Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV) is the etiologic agent of Kaposi's sarcoma (KS), yet the viral genetic factors that lead to the development of KS in KSHV-infected individuals have not been fully elucidated. Nearly, all previous analyses of KSHV genomic evolution and diversity have excluded the three major internal repeat regions: the two origins of lytic replication, internal repeats 1 and 2 (IR1 and IR2), and the latency-associated nuclear antigen (LANA) repeat domain (LANAr). These regions encode protein domains that are essential to the KSHV infection cycle but have been rarely sequenced due to their extended repetitive nature and high guanine and cytosine (GC) content. The limited data available suggest that their sequences and repeat lengths are more heterogeneous across individuals than in the remainder of the KSHV genome. To assess their diversity, the full-length IR1, IR2, and LANAr sequences, tagged with unique molecular identifiers (UMIs), were obtained by Pacific Biosciences' single-molecule real-time sequencing (SMRT-UMI) from twenty-four tumors and six matching oral swabs from sixteen adults in Uganda with advanced KS. Intra-host single-nucleotide variation involved an average of 0.16 per cent of base positions in the repeat regions compared to a nearly identical average of 0.17 per cent of base positions in the remainder of the genome. Tandem repeat unit (TRU) counts varied by only one from the intra-host consensus in a majority of individuals. Including the TRU indels, the average intra-host pairwise identity was 98.3 per cent for IR1, 99.6 per cent for IR2 and 98.9 per cent for LANAr. More individuals had mismatches and variable TRU counts in IR1 (twelve/sixteen) than in IR2 (two/sixteen). There were no open reading frames in the Kaposin coding sequence inside IR2 in at least fifty-five of ninety-six sequences. In summary, the KSHV major internal repeats, like the rest of the genome in individuals with KS, have low diversity. IR1 was the most variable among the repeats, and no intact Kaposin reading frames were present in IR2 of the majority of genomes sampled.
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Affiliation(s)
| | - Dylan H Westfall
- Department of Microbiology, University of Washington, 960 Republican St, Seattle, WA 98109-4325, USA
| | - Scott V Adams
- Global Oncology and Vaccine and Infectious Diseases Division,Fred Hutchinson Cancer Center, 1100 Eastlake Ave, Seattle, 98109-4487 WA, USA
| | - Fred Okuku
- Uganda Cancer Institute, Upper Mulago Hill Road, Kampala, Uganda
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13
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Simpson BP, Yrigollen CM, Izda A, Davidson BL. Targeted long-read sequencing captures CRISPR editing and AAV integration outcomes in brain. Mol Ther 2023; 31:760-773. [PMID: 36617193 PMCID: PMC10014281 DOI: 10.1016/j.ymthe.2023.01.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 12/07/2022] [Accepted: 01/04/2023] [Indexed: 01/09/2023] Open
Abstract
Clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 gene editing is an emerging therapeutic modality that shows promise in Huntington's disease and spinocerebellar ataxia (SCA) mouse models. However, advancing CRISPR-based therapies requires methods to fully define in vivo editing outcomes. Here, we use polymerase-free, targeted long-read nanopore sequencing and evaluate single- and dual-gRNA AAV-CRISPR editing of human ATXN2 in transgenic mouse models of SCA type 2 (SCA2). Unbiased high sequencing coverage showed 10%-25% editing. Along with intended edits there was AAV integration, 1%-2% of which contained the entire AAV genome and were largely unmethylated. More than 150 kb deletions at target loci and rearrangements of the transgenic allele (1%) were also found. In contrast, PCR-based nanopore sequencing showed bias for partial AAV fragments and inverted terminal repeats (ITRs) and failed to detect full-length AAV. Cumulatively this work defines the spectrum of outcomes of CRISPR editing in mouse brain after AAV gene transfer using an unbiased long-read sequencing approach.
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Affiliation(s)
- Bryan P Simpson
- Raymond G. Perelman Center for Cellular and Molecular Therapeutics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA; Cell and Molecular Biology Graduate Group, Biomedical Graduate Studies, University of Pennsylvania, Philadelphia, PA, USA
| | - Carolyn M Yrigollen
- Raymond G. Perelman Center for Cellular and Molecular Therapeutics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Aleksandar Izda
- Raymond G. Perelman Center for Cellular and Molecular Therapeutics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Beverly L Davidson
- Raymond G. Perelman Center for Cellular and Molecular Therapeutics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA; Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA, USA.
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14
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Malekshoar M, Azimi SA, Kaki A, Mousazadeh L, Motaei J, Vatankhah M. CRISPR-Cas9 Targeted Enrichment and Next-Generation Sequencing for Mutation Detection. J Mol Diagn 2023; 25:249-262. [PMID: 36841425 DOI: 10.1016/j.jmoldx.2023.01.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 01/08/2023] [Accepted: 01/27/2023] [Indexed: 02/27/2023] Open
Abstract
Despite the rapid application of next-generation sequencing (NGS) technologies, target sequencing in regions of the genome is often required to diagnose many genetic diseases. Target enrichment can be an effective factor in reducing the cost of sequencing and the duration of sequencing. Recently, several clustered system regularly interspaced short palindromic repeats (CRISPR)-based methods (amplification-free sequencing) have been developed to target enrichment in combination with one of the NGS platforms. CRISPR-based target enrichment strategies act as an auxiliary tool to improve NGS analytical performance, thereby indirectly facilitating nucleic acid detection. The direct DNA cleavage approach by CRISPR-Cas at genome-specific sites enhances the possibility of separating native large fragments from disease-related genomic regions. The CRISPR-Cas can isolate the target region without any amplification; subsequently, long-read sequencing technologies were also implemented. These methods, as promising tools, have the ability to assess genetic and epigenetic composition for clinical application and treatment responses in cancer precision medicine. By modifying CRISPR-based enrichment protocols, it was possible to identify different types of mutations, including structural variants, short tandem repeats, fusion genes, and mobile elements. The Cas9 can specifically eliminate wild-type sequences, and it also enables the enrichment and detection of small amounts of tumor DNA fragments among the highly heterogeneous fragments of wild-type DNA.
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Affiliation(s)
- Mehrdad Malekshoar
- Anesthesiology, Critical Care and Pain Management Research Center, Hormozgan University of Medical Sciences, Bandar Abbas, Iran
| | - Sajad Ataei Azimi
- Department of Hematology-Oncology, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Arastoo Kaki
- Department of Medical Genetics, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
| | - Leila Mousazadeh
- Department of Medical Biotechnology, School of Advanced Medical Sciences, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Jamshid Motaei
- Department of Medical Genetics, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran.
| | - Majid Vatankhah
- Anesthesiology, Critical Care and Pain Management Research Center, Hormozgan University of Medical Sciences, Bandar Abbas, Iran.
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15
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Udine E, Jain A, van Blitterswijk M. Advances in sequencing technologies for amyotrophic lateral sclerosis research. Mol Neurodegener 2023; 18:4. [PMID: 36635726 PMCID: PMC9838075 DOI: 10.1186/s13024-022-00593-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Accepted: 12/23/2022] [Indexed: 01/14/2023] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is caused by upper and lower motor neuron loss and has a fairly rapid disease progression, leading to fatality in an average of 2-5 years after symptom onset. Numerous genes have been implicated in this disease; however, many cases remain unexplained. Several technologies are being used to identify regions of interest and investigate candidate genes. Initial approaches to detect ALS genes include, among others, linkage analysis, Sanger sequencing, and genome-wide association studies. More recently, next-generation sequencing methods, such as whole-exome and whole-genome sequencing, have been introduced. While those methods have been particularly useful in discovering new ALS-linked genes, methodological advances are becoming increasingly important, especially given the complex genetics of ALS. Novel sequencing technologies, like long-read sequencing, are beginning to be used to uncover the contribution of repeat expansions and other types of structural variation, which may help explain missing heritability in ALS. In this review, we discuss how popular and/or upcoming methods are being used to discover ALS genes, highlighting emerging long-read sequencing platforms and their role in aiding our understanding of this challenging disease.
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Affiliation(s)
- Evan Udine
- grid.417467.70000 0004 0443 9942Department of Neuroscience, Mayo Clinic, 4500 San Pablo Road S, Jacksonville, FL 32224 USA ,grid.417467.70000 0004 0443 9942Mayo Clinic Graduate School of Biomedical Sciences, 4500 San Pablo Road S, Jacksonville, FL 32224 USA
| | - Angita Jain
- grid.417467.70000 0004 0443 9942Department of Neuroscience, Mayo Clinic, 4500 San Pablo Road S, Jacksonville, FL 32224 USA ,grid.417467.70000 0004 0443 9942Mayo Clinic Graduate School of Biomedical Sciences, 4500 San Pablo Road S, Jacksonville, FL 32224 USA ,grid.417467.70000 0004 0443 9942Center for Clinical and Translational Sciences, Mayo Clinic, 4500 San Pablo Road S, Jacksonville, FL 32224 USA
| | - Marka van Blitterswijk
- Department of Neuroscience, Mayo Clinic, 4500 San Pablo Road S, Jacksonville, FL, 32224, USA.
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16
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Mani S, Jindal D, Singh M. Gene Therapy, A Potential Therapeutic Tool for Neurological and Neuropsychiatric Disorders: Applications, Challenges and Future Perspective. Curr Gene Ther 2023; 23:20-40. [PMID: 35345999 DOI: 10.2174/1566523222666220328142427] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 01/18/2022] [Accepted: 02/02/2022] [Indexed: 02/08/2023]
Abstract
Neurological and neuropsychiatric disorders are the main risks for the health care system, exhibiting a huge socioeconomic load. The available range of pharmacotherapeutics mostly provides palliative consequences and fails to treat such conditions. The molecular etiology of various neurological and neuropsychiatric disorders is mostly associated with a change in genetic background, which can be inherited/triggered by other environmental factors. To address such conditions, gene therapy is considered a potential approach claiming a permanent cure of the disease primarily by deletion, silencing, or edition of faulty genes and by insertion of healthier genes. In gene therapy, vectors (viral/nonvial) play an important role in delivering the desired gene to a specific region of the brain. Targeted gene therapy has unraveled opportunities for the treatment of many neurological and neuropsychiatric disorders. For improved gene delivery, the current techniques mainly focus on designing a precise viral vector, plasmid transfection, nanotechnology, microRNA, and in vivo clustered regulatory interspaced short palindromic repeats (CRISPR)-based therapy. These latest techniques have great benefits in treating predominant neurological and neurodevelopmental disorders, including Parkinson's disease, Alzheimer's disease, and autism spectrum disorder, as well as rarer diseases. Nevertheless, all these delivery methods have their limitations, including immunogenic reactions, off-target effects, and a deficiency of effective biomarkers to appreciate the effectiveness of therapy. In this review, we present a summary of the current methods in targeted gene delivery, followed by the limitations and future direction of gene therapy for the cure of neurological and neuropsychiatric disorders.
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Affiliation(s)
- Shalini Mani
- Department of Biotechnology, Centre for Emerging Diseases, Jaypee Institute of Information Technology, Noida, U.P., India
| | - Divya Jindal
- Department of Biotechnology, Centre for Emerging Diseases, Jaypee Institute of Information Technology, Noida, U.P., India
| | - Manisha Singh
- Department of Biotechnology, Centre for Emerging Diseases, Jaypee Institute of Information Technology, Noida, U.P., India
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17
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Taylor A, Barros D, Gobet N, Schuepbach T, McAllister B, Aeschbach L, Randall E, Trofimenko E, Heuchan E, Barszcz P, Ciosi M, Morgan J, Hafford-Tear N, Davidson A, Massey T, Monckton D, Jones L, network REGISTRYH, Xenarios I, Dion V. Repeat Detector: versatile sizing of expanded tandem repeats and identification of interrupted alleles from targeted DNA sequencing. NAR Genom Bioinform 2022; 4:lqac089. [PMID: 36478959 PMCID: PMC9719798 DOI: 10.1093/nargab/lqac089] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 10/25/2022] [Accepted: 11/08/2022] [Indexed: 12/07/2022] Open
Abstract
Targeted DNA sequencing approaches will improve how the size of short tandem repeats is measured for diagnostic tests and preclinical studies. The expansion of these sequences causes dozens of disorders, with longer tracts generally leading to a more severe disease. Interrupted alleles are sometimes present within repeats and can alter disease manifestation. Determining repeat size mosaicism and identifying interruptions in targeted sequencing datasets remains a major challenge. This is in part because standard alignment tools are ill-suited for repetitive and unstable sequences. To address this, we have developed Repeat Detector (RD), a deterministic profile weighting algorithm for counting repeats in targeted sequencing data. We tested RD using blood-derived DNA samples from Huntington's disease and Fuchs endothelial corneal dystrophy patients sequenced using either Illumina MiSeq or Pacific Biosciences single-molecule, real-time sequencing platforms. RD was highly accurate in determining repeat sizes of 609 blood-derived samples from Huntington's disease individuals and did not require prior knowledge of the flanking sequences. Furthermore, RD can be used to identify alleles with interruptions and provide a measure of repeat instability within an individual. RD is therefore highly versatile and may find applications in the diagnosis of expanded repeat disorders and in the development of novel therapies.
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Affiliation(s)
- Alysha S Taylor
- UK Dementia Research Institute, Cardiff University, Hadyn Ellis Building, Maindy Road, Cardiff, CF24 4HQ, UK
| | - Dinis Barros
- Centre for Integrative Genomics, University of Lausanne, Bâtiment Génopode, 1015 Lausanne, Switzerland
| | - Nastassia Gobet
- Centre for Integrative Genomics, University of Lausanne, Bâtiment Génopode, 1015 Lausanne, Switzerland
| | - Thierry Schuepbach
- Vital-IT Group, Swiss Institute of Bioinformatics, 1015 Lausanne, Switzerland
- Newbiologix, Ch. De la corniche 6-8, 1066 Epalinges, Switzerland
| | - Branduff McAllister
- MRC Centre for Neuropsychiatric Genetics and Genomics, Cardiff University, Hadyn Ellis Building, Maindy Road, Cardiff CF24 4HQ, UK
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Lorene Aeschbach
- Centre for Integrative Genomics, University of Lausanne, Bâtiment Génopode, 1015 Lausanne, Switzerland
| | - Emma L Randall
- UK Dementia Research Institute, Cardiff University, Hadyn Ellis Building, Maindy Road, Cardiff, CF24 4HQ, UK
| | - Evgeniya Trofimenko
- Centre for Integrative Genomics, University of Lausanne, Bâtiment Génopode, 1015 Lausanne, Switzerland
- Sorbonne Université, École normale supérieure, PSL University, CNRS, Laboratoire des biomolécules, LBM, 75005 Paris, France
| | - Eleanor R Heuchan
- UK Dementia Research Institute, Cardiff University, Hadyn Ellis Building, Maindy Road, Cardiff, CF24 4HQ, UK
| | - Paula Barszcz
- Centre for Integrative Genomics, University of Lausanne, Bâtiment Génopode, 1015 Lausanne, Switzerland
| | - Marc Ciosi
- School of Molecular Biosciences, College of Medical, Veterinary and Life Sciences, Davidson Building, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Joanne Morgan
- MRC Centre for Neuropsychiatric Genetics and Genomics, Cardiff University, Hadyn Ellis Building, Maindy Road, Cardiff CF24 4HQ, UK
| | | | - Alice E Davidson
- UCL Institute of Ophthalmology, 11-43 Bath Street, London, EC1V 9EL UK
| | - Thomas H Massey
- MRC Centre for Neuropsychiatric Genetics and Genomics, Cardiff University, Hadyn Ellis Building, Maindy Road, Cardiff CF24 4HQ, UK
| | - Darren G Monckton
- School of Molecular Biosciences, College of Medical, Veterinary and Life Sciences, Davidson Building, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Lesley Jones
- MRC Centre for Neuropsychiatric Genetics and Genomics, Cardiff University, Hadyn Ellis Building, Maindy Road, Cardiff CF24 4HQ, UK
| | | | - Ioannis Xenarios
- Centre for Integrative Genomics, University of Lausanne, Bâtiment Génopode, 1015 Lausanne, Switzerland
- Health2030 Genome Center, Ch des Mines 14, 1202 Genève, Switzerland
| | - Vincent Dion
- UK Dementia Research Institute, Cardiff University, Hadyn Ellis Building, Maindy Road, Cardiff, CF24 4HQ, UK
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18
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Conlin LK, Aref-Eshghi E, McEldrew DA, Luo M, Rajagopalan R. Long-read sequencing for molecular diagnostics in constitutional genetic disorders. Hum Mutat 2022; 43:1531-1544. [PMID: 36086952 PMCID: PMC9561063 DOI: 10.1002/humu.24465] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 09/03/2022] [Accepted: 09/06/2022] [Indexed: 11/11/2022]
Abstract
Long-read sequencing (LRS) has been around for more than a decade, but widespread adoption of the technology has been slow due to the perceived high error rates and high sequencing cost. This is changing due to the recent advancements to produce highly accurate sequences and the reducing costs. LRS promises significant improvement over short read sequencing in four major areas: (1) better detection of structural variation (2) better resolution of highly repetitive or nonunique regions (3) accurate long-range haplotype phasing and (4) the detection of base modifications natively from the sequencing data. Several successful applications of LRS have demonstrated its ability to resolve molecular diagnoses where short-read sequencing fails to identify a cause. However, the argument for increased diagnostic yield from LRS remains to be validated. Larger cohort studies may be required to establish the realistic boundaries of LRS's clinical utility and analytical validity, as well as the development of standards for clinical applications. We discuss the limitations of the current standard of care, and contrast with the applications and advantages of two major LRS platforms, PacBio and Oxford Nanopore, for molecular diagnostics of constitutional disorders, and present a critical argument about the potential of LRS in diagnostic settings.
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Affiliation(s)
- Laura K. Conlin
- Division of Genomic Diagnostics, Department of Pathology and Laboratory Medicine, Children’s Hospital of Philadelphia, Philadelphia, PA 19104
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - Erfan Aref-Eshghi
- Division of Genomic Diagnostics, Department of Pathology and Laboratory Medicine, Children’s Hospital of Philadelphia, Philadelphia, PA 19104
| | - Deborah A. McEldrew
- Division of Genomic Diagnostics, Department of Pathology and Laboratory Medicine, Children’s Hospital of Philadelphia, Philadelphia, PA 19104
| | - Minjie Luo
- Division of Genomic Diagnostics, Department of Pathology and Laboratory Medicine, Children’s Hospital of Philadelphia, Philadelphia, PA 19104
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - Ramakrishnan Rajagopalan
- Division of Genomic Diagnostics, Department of Pathology and Laboratory Medicine, Children’s Hospital of Philadelphia, Philadelphia, PA 19104
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104
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19
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Liang Q, Liu Y, Liu Y, Duan R, Meng W, Zhan J, Xia J, Mao A, Liang D, Wu L. Comprehensive Analysis of Fragile X Syndrome: Full Characterization of the FMR1 Locus by Long-Read Sequencing. Clin Chem 2022; 68:1529-1540. [PMID: 36171182 DOI: 10.1093/clinchem/hvac154] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Accepted: 07/21/2022] [Indexed: 11/14/2022]
Abstract
BACKGROUND Fragile X syndrome (FXS) is the most frequent cause of inherited X-linked intellectual disability. Conventional FXS genetic testing methods mainly focus on FMR1 CGG expansions and fail to identify AGG interruptions, rare intragenic variants, and large gene deletions. METHODS A long-range PCR and long-read sequencing-based assay termed comprehensive analysis of FXS (CAFXS) was developed and evaluated in Coriell and clinical samples by comparing to Southern blot analysis and triplet repeat-primed PCR (TP-PCR). RESULTS CAFXS accurately detected the number of CGG repeats in the range of 93 to at least 940 with mass fraction of 0.5% to 1% in the background of normal alleles, which was 2-4-fold analytically more sensitive than TP-PCR. All categories of mutations detected by control methods, including full mutations in 30 samples, were identified by CAFXS for all 62 clinical samples. CAFXS accurately determined AGG interruptions in all 133 alleles identified, even in mosaic alleles. CAFXS successfully identified 2 rare intragenic variants including the c.879A > C variant in exon 9 and a 697-bp microdeletion flanking upstream of CGG repeats, which disrupted primer annealing in TP-PCR assay. In addition, CAFXS directly determined the breakpoints of a 237.1-kb deletion and a 774.0-kb deletion encompassing the entire FMR1 gene in 2 samples. CONCLUSIONS Long-read sequencing-based CAFXS represents a comprehensive assay for identifying FMR1 CGG expansions, AGG interruptions, rare intragenic variants, and large gene deletions, which greatly improves the genetic screening and diagnosis for FXS.
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Affiliation(s)
- Qiaowei Liang
- Department of Medical Genetics, Hunan Jiahui Genetics Hospital, Changsha, Hunan, China
| | - Yingdi Liu
- Center for Medical Genetics and Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, Changsha, Hunan, China
| | - Yaning Liu
- Department of Medical Genetics, Hunan Jiahui Genetics Hospital, Changsha, Hunan, China
| | - Ranhui Duan
- Center for Medical Genetics and Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, Changsha, Hunan, China
| | - Wanli Meng
- Berry Genomics Corporation, Beijing, China
| | | | - Jiahui Xia
- Department of Medical Genetics, Hunan Jiahui Genetics Hospital, Changsha, Hunan, China
| | - Aiping Mao
- Berry Genomics Corporation, Beijing, China
| | - Desheng Liang
- Department of Medical Genetics, Hunan Jiahui Genetics Hospital, Changsha, Hunan, China.,Center for Medical Genetics and Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, Changsha, Hunan, China
| | - Lingqian Wu
- Department of Medical Genetics, Hunan Jiahui Genetics Hospital, Changsha, Hunan, China.,Center for Medical Genetics and Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, Changsha, Hunan, China
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20
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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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21
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Third-Generation Cytogenetic Analysis: Diagnostic Application of Long-Read Sequencing. J Mol Diagn 2022; 24:711-718. [PMID: 35526834 DOI: 10.1016/j.jmoldx.2022.03.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Revised: 02/23/2022] [Accepted: 03/25/2022] [Indexed: 11/21/2022] Open
Abstract
Copy number variants (CNVs) play important roles in the pathogenesis of several genetic syndromes. Traditional and molecular karyotyping are considered the first-tier diagnostic tests to detect macroscopic and cryptic deletions/duplications. However, their time-consuming and laborious experimental protocols protract diagnostic times from 3 to 15 days. Nanopore sequencing has the ability to reduce time to results for the detection of CNVs with the same resolution of current state-of-the-art diagnostic tests. Nanopore sequencing was compared to molecular karyotyping for the detection of pathogenic CNVs of seven patients with previously diagnosed causative CNVs of different sizes and cellular fractions. Larger chromosomal anomalies included trisomy 21 and mosaic tetrasomy 12p. Among smaller CNVs, two genomic imbalances of 1.3 Mb, a small deletion of 170 kb, and two mosaic deletions (1.2 Mb and 408 kb) were tested. DNA was sequenced and data generated during runs were analyzed in online mode. All pathogenic CNVs were identified with detection time inversely proportional to size and cellular fraction. Aneuploidies were called after only 30 minutes of sequencing, whereas 30 hours were needed to call small CNVs. These results demonstrate the clinical utility of our approach that allows the molecular diagnosis of genomic disorders within a 30-minute to 30-hour time frame and its easy implementation as a routinary diagnostic tool.
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22
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Marsili L, Duque KR, Bode RL, Kauffman MA, Espay AJ. Uncovering Essential Tremor Genetics: The Promise of Long-Read Sequencing. Front Neurol 2022; 13:821189. [PMID: 35401394 PMCID: PMC8983820 DOI: 10.3389/fneur.2022.821189] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Accepted: 02/25/2022] [Indexed: 12/23/2022] Open
Abstract
Long-read sequencing (LRS) technologies have been recently introduced to overcome intrinsic limitations of widely-used next-generation sequencing (NGS) technologies, namely the sequencing limited to short-read fragments (150–300 base pairs). Since its introduction, LRS has permitted many successes in unraveling hidden mutational mechanisms. One area in clinical neurology in need of rethinking as it applies to genetic mechanisms is essential tremor (ET). This disorder, among the most common in neurology, is a syndrome often exhibiting an autosomal dominant pattern of inheritance whose large phenotypic spectrum suggest a multitude of genetic etiologies. Exome sequencing has revealed the genetic etiology only in rare ET families (FUS, SORT1, SCN4A, NOS3, KCNS2, HAPLN4/BRAL2, and USP46). We hypothesize that a reason for this shortcoming may be non-classical genetic mechanism(s) underpinning ET, among them trinucleotide, tetranucleotide, or pentanucleotide repeat disorders. In support of this hypothesis, trinucleotide (e.g., GGC repeats in NOTCH2NLC) and pentanucleotide repeat disorders (e.g., ATTTC repeats in STARD7) have been revealed as pathogenic in patients with a past history of what has come to be referred to as “ET plus,” bilateral hand tremor associated with epilepsy and/or leukoencephalopathy. A systematic review of LRS in neurodegenerative disorders showed that 10 of the 22 (45%) genetic etiologies ascertained by LRS include tremor in their phenotypic spectrum, suggesting that future clinical applications of LRS for tremor disorders may uncover genetic subtypes of familial ET that have eluded NGS, particularly those with associated leukoencephalopathy or family history of epilepsy. LRS provides a pathway for potentially uncovering novel genes and genetic mechanisms, helping narrow the large proportion of “idiopathic” ET.
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Affiliation(s)
- Luca Marsili
- James J. and Joan A. Gardner Center for Parkinson's Disease and Movement Disorders, Department of Neurology, University of Cincinnati, Cincinnati, OH, United States
| | - Kevin R. Duque
- James J. and Joan A. Gardner Center for Parkinson's Disease and Movement Disorders, Department of Neurology, University of Cincinnati, Cincinnati, OH, United States
| | - Rachel L. Bode
- James J. and Joan A. Gardner Center for Parkinson's Disease and Movement Disorders, Department of Neurology, University of Cincinnati, Cincinnati, OH, United States
| | - Marcelo A. Kauffman
- Consultorio y Laboratorio de Neurogenética, Centro Universitario de Neurología José María Ramos Mejía, Buenos Aires, Argentina
| | - Alberto J. Espay
- James J. and Joan A. Gardner Center for Parkinson's Disease and Movement Disorders, Department of Neurology, University of Cincinnati, Cincinnati, OH, United States
- *Correspondence: Alberto J. Espay
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23
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Höijer I, Emmanouilidou A, Östlund R, van Schendel R, Bozorgpana S, Tijsterman M, Feuk L, Gyllensten U, den Hoed M, Ameur A. CRISPR-Cas9 induces large structural variants at on-target and off-target sites in vivo that segregate across generations. Nat Commun 2022; 13:627. [PMID: 35110541 PMCID: PMC8810904 DOI: 10.1038/s41467-022-28244-5] [Citation(s) in RCA: 54] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Accepted: 01/04/2022] [Indexed: 02/07/2023] Open
Abstract
CRISPR-Cas9 genome editing has potential to cure diseases without current treatments, but therapies must be safe. Here we show that CRISPR-Cas9 editing can introduce unintended mutations in vivo, which are passed on to the next generation. By editing fertilized zebrafish eggs using four guide RNAs selected for off-target activity in vitro, followed by long-read sequencing of DNA from >1100 larvae, juvenile and adult fish across two generations, we find that structural variants (SVs), i.e., insertions and deletions ≥50 bp, represent 6% of editing outcomes in founder larvae. These SVs occur both at on-target and off-target sites. Our results also illustrate that adult founder zebrafish are mosaic in their germ cells, and that 26% of their offspring carries an off-target mutation and 9% an SV. Hence, pre-testing for off-target activity and SVs using patient material is advisable in clinical applications, to reduce the risk of unanticipated effects with potentially large implications.
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Affiliation(s)
- Ida Höijer
- Science for Life Laboratory, Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden.
| | - Anastasia Emmanouilidou
- Science for Life Laboratory, Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
- The Beijer laboratory and Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
| | - Rebecka Östlund
- Science for Life Laboratory, Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
| | - Robin van Schendel
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Selma Bozorgpana
- Science for Life Laboratory, Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
| | - Marcel Tijsterman
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Lars Feuk
- Science for Life Laboratory, Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
| | - Ulf Gyllensten
- Science for Life Laboratory, Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
| | - Marcel den Hoed
- Science for Life Laboratory, Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
- The Beijer laboratory and Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
| | - Adam Ameur
- Science for Life Laboratory, Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden.
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24
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Detecting MUC1 Variants in Patients Clinicopathologically Diagnosed With Having Autosomal Dominant Tubulointerstitial Kidney Disease. Kidney Int Rep 2022; 7:857-866. [PMID: 35497811 PMCID: PMC9039432 DOI: 10.1016/j.ekir.2021.12.037] [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: 10/19/2021] [Revised: 12/15/2021] [Accepted: 12/28/2021] [Indexed: 11/24/2022] Open
Abstract
Introduction Autosomal dominant tubulointerstitial kidney disease (ADTKD)-MUC1 is predominantly caused by frameshift mutations owing to a single-base insertion into the variable number tandem repeat (VNTR) region in MUC1. Because of the complexity of the variant hotspot, identification using short-read sequencers (SRSs) is challenging. Although recent studies have revealed the usefulness of long-read sequencers (LRSs), the prevalence of MUC1 variants in patients with clinically suspected ADTKD remains unknown. We aimed to clarify this prevalence and the genetic characteristics and clinical manifestations of ADTKD-MUC1 in a Japanese population using an SRS and an LRS. Methods From January 2015 to December 2019, genetic analysis was performed using an SRS in 48 patients with clinically suspected ADTKD. Additional analyses were conducted using an LRS in patients with negative SRS results. Results Short-read sequencing results revealed MUC1 variants in 1 patient harboring a cytosine insertion in the second repeat unit of the VNTR region; however, deeper VNTR regions could not be read by the SRS. Therefore, we conducted long-read sequencing analysis of 39 cases and detected MUC1 VNTR variants in 8 patients (in total, 9 patients from unrelated families). With the inclusion of family-affected patients (n = 31), the median age at the development of end-stage kidney disease (ESKD) was 45 years (95% CI: 40–40 years). Conclusion In Japan, the detection rate of MUC1 variants in patients with clinically suspected ADTKD was 18.8%. More than 20% of patients with negative SRS results had MUC1 variants detected by an LRS.
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25
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Gene Therapy Approach with an Emphasis on Growth Factors: Theoretical and Clinical Outcomes in Neurodegenerative Diseases. Mol Neurobiol 2021; 59:191-233. [PMID: 34655056 PMCID: PMC8518903 DOI: 10.1007/s12035-021-02555-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Accepted: 09/05/2021] [Indexed: 12/11/2022]
Abstract
The etiology of many neurological diseases affecting the central nervous system (CNS) is unknown and still needs more effective and specific therapeutic approaches. Gene therapy has a promising future in treating neurodegenerative disorders by correcting the genetic defects or by therapeutic protein delivery and is now an attraction for neurologists to treat brain disorders, like Alzheimer’s disease, Parkinson’s disease, amyotrophic lateral sclerosis, spinal muscular atrophy, spinocerebellar ataxia, epilepsy, Huntington’s disease, stroke, and spinal cord injury. Gene therapy allows the transgene induction, with a unique expression in cells’ substrate. This article mainly focuses on the delivering modes of genetic materials in the CNS, which includes viral and non-viral vectors and their application in gene therapy. Despite the many clinical trials conducted so far, data have shown disappointing outcomes. The efforts done to improve outcomes, efficacy, and safety in the identification of targets in various neurological disorders are also discussed here. Adapting gene therapy as a new therapeutic approach for treating neurological disorders seems to be promising, with early detection and delivery of therapy before the neuron is lost, helping a lot the development of new therapeutic options to translate to the clinic.
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26
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Mouro Pinto R, Arning L, Giordano JV, Razghandi P, Andrew MA, Gillis T, Correia K, Mysore JS, Grote Urtubey DM, Parwez CR, von Hein SM, Clark HB, Nguyen HP, Förster E, Beller A, Jayadaev S, Keene CD, Bird TD, Lucente D, Vonsattel JP, Orr H, Saft C, Petrasch-Parwez E, Wheeler VC. Patterns of CAG repeat instability in the central nervous system and periphery in Huntington's disease and in spinocerebellar ataxia type 1. Hum Mol Genet 2021; 29:2551-2567. [PMID: 32761094 PMCID: PMC7471505 DOI: 10.1093/hmg/ddaa139] [Citation(s) in RCA: 66] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Revised: 06/24/2020] [Accepted: 07/01/2020] [Indexed: 12/23/2022] Open
Abstract
The expanded HTT CAG repeat causing Huntington’s disease (HD) exhibits somatic expansion proposed to drive the rate of disease onset by eliciting a pathological process that ultimately claims vulnerable cells. To gain insight into somatic expansion in humans, we performed comprehensive quantitative analyses of CAG expansion in ~50 central nervous system (CNS) and peripheral postmortem tissues from seven adult-onset and one juvenile-onset HD individual. We also assessed ATXN1 CAG repeat expansion in brain regions of an individual with a neurologically and pathologically distinct repeat expansion disorder, spinocerebellar ataxia type 1 (SCA1). Our findings reveal similar profiles of tissue instability in all HD individuals, which, notably, were also apparent in the SCA1 individual. CAG expansion was observed in all tissues, but to different degrees, with multiple cortical regions and neostriatum tending to have the greatest instability in the CNS, and liver in the periphery. These patterns indicate different propensities for CAG expansion contributed by disease locus-independent trans-factors and demonstrate that expansion per se is not sufficient to cause cell type or disease-specific pathology. Rather, pathology may reflect distinct toxic processes triggered by different repeat lengths across cell types and diseases. We also find that the HTT CAG length-dependent expansion propensity of an individual is reflected in all tissues and in cerebrospinal fluid. Our data indicate that peripheral cells may be a useful source to measure CAG expansion in biomarker assays for therapeutic efforts, prompting efforts to dissect underlying mechanisms of expansion that may differ between the brain and periphery.
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Affiliation(s)
- Ricardo Mouro Pinto
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA.,Department of Neurology, Harvard Medical School, Boston, MA 02115, USA
| | - Larissa Arning
- Department of Human Genetics, Ruhr-University Bochum, Bochum 44780, Germany
| | - James V Giordano
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Pedram Razghandi
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Marissa A Andrew
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Tammy Gillis
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Kevin Correia
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Jayalakshmi S Mysore
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
| | | | - Constanze R Parwez
- Department of Neuroanatomy and Molecular Brain Research, Institute of Anatomy, Ruhr-University Bochum, Bochum 44780, Germany
| | - Sarah M von Hein
- Department of Neurology, Huntington Centre NRW, St. Josef-Hospital, Ruhr-University Bochum, Bochum 44791, Germany
| | - H Brent Clark
- Department of Laboratory Medicine and Pathology, Institute of Translational Neuroscience, University of Minnesota Medical School, Minneapolis, MN 55455, USA
| | - Huu Phuc Nguyen
- Department of Human Genetics, Ruhr-University Bochum, Bochum 44780, Germany
| | - Eckart Förster
- Department of Neuroanatomy and Molecular Brain Research, Institute of Anatomy, Ruhr-University Bochum, Bochum 44780, Germany
| | - Allison Beller
- Department of Pathology, University of Washington, Seattle, Washington 98195, USA
| | - Suman Jayadaev
- Department of Neurology, University of Washington, Seattle, Washington 98195, USA
| | - C Dirk Keene
- Department of Pathology, University of Washington, Seattle, Washington 98195, USA
| | - Thomas D Bird
- Department of Neurology, University of Washington, Seattle, Washington 98195, USA.,Department of Medicine, University of Washington, Seattle, Washington 98195, USA.,Geriatrics Research Education and Clinical Center, VA Puget Sound Medical Center, Seattle, WA 98108, USA
| | - Diane Lucente
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Jean-Paul Vonsattel
- Department of Pathology and Cell Biology, Columbia University Medical Center and the New York Presbyterian Hospital, New York, NY 10032, USA
| | - Harry Orr
- Department of Laboratory Medicine and Pathology, Institute of Translational Neuroscience, University of Minnesota Medical School, Minneapolis, MN 55455, USA
| | - Carsten Saft
- Department of Neurology, Huntington Centre NRW, St. Josef-Hospital, Ruhr-University Bochum, Bochum 44791, Germany
| | - Elisabeth Petrasch-Parwez
- Department of Neuroanatomy and Molecular Brain Research, Institute of Anatomy, Ruhr-University Bochum, Bochum 44780, Germany
| | - Vanessa C Wheeler
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA.,Department of Neurology, Harvard Medical School, Boston, MA 02115, USA
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27
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Arango D, Bittar A, Esmeral NP, Ocasión C, Muñoz-Camargo C, Cruz JC, Reyes LH, Bloch NI. Understanding the Potential of Genome Editing in Parkinson's Disease. Int J Mol Sci 2021; 22:9241. [PMID: 34502143 PMCID: PMC8430539 DOI: 10.3390/ijms22179241] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Revised: 07/07/2021] [Accepted: 07/08/2021] [Indexed: 01/05/2023] Open
Abstract
CRISPR is a simple and cost-efficient gene-editing technique that has become increasingly popular over the last decades. Various CRISPR/Cas-based applications have been developed to introduce changes in the genome and alter gene expression in diverse systems and tissues. These novel gene-editing techniques are particularly promising for investigating and treating neurodegenerative diseases, including Parkinson's disease, for which we currently lack efficient disease-modifying treatment options. Gene therapy could thus provide treatment alternatives, revolutionizing our ability to treat this disease. Here, we review our current knowledge on the genetic basis of Parkinson's disease to highlight the main biological pathways that become disrupted in Parkinson's disease and their potential as gene therapy targets. Next, we perform a comprehensive review of novel delivery vehicles available for gene-editing applications, critical for their successful application in both innovative research and potential therapies. Finally, we review the latest developments in CRISPR-based applications and gene therapies to understand and treat Parkinson's disease. We carefully examine their advantages and shortcomings for diverse gene-editing applications in the brain, highlighting promising avenues for future research.
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Affiliation(s)
- David Arango
- Department of Biomedical Engineering, Universidad de los Andes, Bogotá 111711, Colombia; (D.A.); (A.B.); (N.P.E.); (C.M.-C.); (J.C.C.)
| | - Amaury Bittar
- Department of Biomedical Engineering, Universidad de los Andes, Bogotá 111711, Colombia; (D.A.); (A.B.); (N.P.E.); (C.M.-C.); (J.C.C.)
| | - Natalia P. Esmeral
- Department of Biomedical Engineering, Universidad de los Andes, Bogotá 111711, Colombia; (D.A.); (A.B.); (N.P.E.); (C.M.-C.); (J.C.C.)
| | - Camila Ocasión
- Grupo de Diseño de Productos y Procesos, Department of Chemical and Food Engineering, Universidad de los Andes, Bogotá 111711, Colombia; (C.O.); (L.H.R.)
| | - Carolina Muñoz-Camargo
- Department of Biomedical Engineering, Universidad de los Andes, Bogotá 111711, Colombia; (D.A.); (A.B.); (N.P.E.); (C.M.-C.); (J.C.C.)
| | - Juan C. Cruz
- Department of Biomedical Engineering, Universidad de los Andes, Bogotá 111711, Colombia; (D.A.); (A.B.); (N.P.E.); (C.M.-C.); (J.C.C.)
| | - Luis H. Reyes
- Grupo de Diseño de Productos y Procesos, Department of Chemical and Food Engineering, Universidad de los Andes, Bogotá 111711, Colombia; (C.O.); (L.H.R.)
| | - Natasha I. Bloch
- Department of Biomedical Engineering, Universidad de los Andes, Bogotá 111711, Colombia; (D.A.); (A.B.); (N.P.E.); (C.M.-C.); (J.C.C.)
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28
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Chiu R, Rajan-Babu IS, Friedman JM, Birol I. Straglr: discovering and genotyping tandem repeat expansions using whole genome long-read sequences. Genome Biol 2021; 22:224. [PMID: 34389037 PMCID: PMC8361843 DOI: 10.1186/s13059-021-02447-3] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Accepted: 07/26/2021] [Indexed: 12/11/2022] Open
Abstract
Tandem repeat (TR) expansion is the underlying cause of over 40 neurological disorders. Long-read sequencing offers an exciting avenue over conventional technologies for detecting TR expansions. Here, we present Straglr, a robust software tool for both targeted genotyping and novel expansion detection from long-read alignments. We benchmark Straglr using various simulations, targeted genotyping data of cell lines carrying expansions of known diseases, and whole genome sequencing data with chromosome-scale assembly. Our results suggest that Straglr may be useful for investigating disease-associated TR expansions using long-read sequencing.
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Affiliation(s)
- Readman Chiu
- Canada's Michael Smith Genome Sciences Centre, BC Cancer, Vancouver, BC, V5Z 4S6, Canada
| | - Indhu-Shree Rajan-Babu
- Department of Medical Genetics, University of British Columbia, Vancouver, BC, V6T 1Z3, Canada
- BC Children's Hospital Research Institute, Vancouver, BC, V5Z 4H4, Canada
- Department of Medical and Molecular Genetics, King's College London, Strand, London, WC2R 2LS, UK
| | - Jan M Friedman
- Department of Medical Genetics, University of British Columbia, Vancouver, BC, V6T 1Z3, Canada
- BC Children's Hospital Research Institute, Vancouver, BC, V5Z 4H4, Canada
| | - Inanc Birol
- Canada's Michael Smith Genome Sciences Centre, BC Cancer, Vancouver, BC, V5Z 4S6, Canada.
- Department of Medical Genetics, University of British Columbia, Vancouver, BC, V6T 1Z3, Canada.
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29
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Su Y, Fan L, Shi C, Wang T, Zheng H, Luo H, Zhang S, Hu Z, Fan Y, Dong Y, Yang J, Mao C, Xu Y. Deciphering Neurodegenerative Diseases Using Long-Read Sequencing. Neurology 2021; 97:423-433. [PMID: 34389649 PMCID: PMC8408508 DOI: 10.1212/wnl.0000000000012466] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Accepted: 06/23/2021] [Indexed: 11/15/2022] Open
Abstract
Neurodegenerative diseases exhibit chronic progressive lesions in the central and peripheral nervous systems with unclear causes. The search for pathogenic mutations in human neurodegenerative diseases has benefited from massively parallel short-read sequencers. However, genomic regions, including repetitive elements, especially with high/low GC content, are far beyond the capability of conventional approaches. Recently, long-read single-molecule DNA sequencing technologies have emerged and enabled researchers to study genomes, transcriptomes, and metagenomes at unprecedented resolutions. The identification of novel mutations in unresolved neurodegenerative disorders, the characterization of causative repeat expansions, and the direct detection of epigenetic modifications on naive DNA by virtue of long-read sequencers will further expand our understanding of neurodegenerative diseases. In this article, we review and compare 2 prevailing long-read sequencing technologies, Pacific Biosciences and Oxford Nanopore Technologies, and discuss their applications in neurodegenerative diseases.
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Affiliation(s)
- Yun Su
- Department of Neurology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, Henan, P. R. China.,The Academy of Medical Sciences of Zhengzhou University, Zhengzhou University, Zhengzhou, Henan, P. R. China.,Henan Key Laboratory of Cerebrovascular Diseases, The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, Henan, P. R. China
| | - Liyuan Fan
- Department of Neurology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, Henan, P. R. China.,The Academy of Medical Sciences of Zhengzhou University, Zhengzhou University, Zhengzhou, Henan, P. R. China.,Henan Key Laboratory of Cerebrovascular Diseases, The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, Henan, P. R. China
| | - Changhe Shi
- Department of Neurology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, Henan, P. R. China.,The Academy of Medical Sciences of Zhengzhou University, Zhengzhou University, Zhengzhou, Henan, P. R. China.,Henan Key Laboratory of Cerebrovascular Diseases, The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, Henan, P. R. China.,Sino-British Research Centre for Molecular Oncology, National Centre for International Research in Cell and Gene Therapy, School of Basic Medical Sciences, Academy of Medical Sciences, Zhengzhou University, Zhengzhou, Henan, P. R. China
| | - Tai Wang
- Department of Neurology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, Henan, P. R. China.,The Academy of Medical Sciences of Zhengzhou University, Zhengzhou University, Zhengzhou, Henan, P. R. China
| | - Huimin Zheng
- Department of Neurology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, Henan, P. R. China.,The Academy of Medical Sciences of Zhengzhou University, Zhengzhou University, Zhengzhou, Henan, P. R. China.,Henan Key Laboratory of Cerebrovascular Diseases, The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, Henan, P. R. China
| | - Haiyang Luo
- Department of Neurology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, Henan, P. R. China.,The Academy of Medical Sciences of Zhengzhou University, Zhengzhou University, Zhengzhou, Henan, P. R. China.,Henan Key Laboratory of Cerebrovascular Diseases, The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, Henan, P. R. China
| | - Shuo Zhang
- Department of Neurology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, Henan, P. R. China.,The Academy of Medical Sciences of Zhengzhou University, Zhengzhou University, Zhengzhou, Henan, P. R. China.,Henan Key Laboratory of Cerebrovascular Diseases, The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, Henan, P. R. China
| | - Zhengwei Hu
- Department of Neurology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, Henan, P. R. China.,The Academy of Medical Sciences of Zhengzhou University, Zhengzhou University, Zhengzhou, Henan, P. R. China.,Henan Key Laboratory of Cerebrovascular Diseases, The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, Henan, P. R. China
| | - Yu Fan
- Department of Neurology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, Henan, P. R. China.,The Academy of Medical Sciences of Zhengzhou University, Zhengzhou University, Zhengzhou, Henan, P. R. China.,Henan Key Laboratory of Cerebrovascular Diseases, The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, Henan, P. R. China
| | - Yali Dong
- Department of Neurology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, Henan, P. R. China.,The Academy of Medical Sciences of Zhengzhou University, Zhengzhou University, Zhengzhou, Henan, P. R. China.,Henan Key Laboratory of Cerebrovascular Diseases, The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, Henan, P. R. China
| | - Jing Yang
- Department of Neurology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, Henan, P. R. China.,Henan Key Laboratory of Cerebrovascular Diseases, The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, Henan, P. R. China.,Institute of Neuroscience, Zhengzhou University, Zhengzhou, Henan, P. R. China
| | - Chengyuan Mao
- Department of Neurology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, Henan, P. R. China.,The Academy of Medical Sciences of Zhengzhou University, Zhengzhou University, Zhengzhou, Henan, P. R. China.,Henan Key Laboratory of Cerebrovascular Diseases, The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, Henan, P. R. China.,Sino-British Research Centre for Molecular Oncology, National Centre for International Research in Cell and Gene Therapy, School of Basic Medical Sciences, Academy of Medical Sciences, Zhengzhou University, Zhengzhou, Henan, P. R. China
| | - Yuming Xu
- Department of Neurology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, Henan, P. R. China .,Henan Key Laboratory of Cerebrovascular Diseases, The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, Henan, P. R. China.,Institute of Neuroscience, Zhengzhou University, Zhengzhou, Henan, P. R. China
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30
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Chintalaphani SR, Pineda SS, Deveson IW, Kumar KR. An update on the neurological short tandem repeat expansion disorders and the emergence of long-read sequencing diagnostics. Acta Neuropathol Commun 2021; 9:98. [PMID: 34034831 PMCID: PMC8145836 DOI: 10.1186/s40478-021-01201-x] [Citation(s) in RCA: 80] [Impact Index Per Article: 26.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Accepted: 05/17/2021] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Short tandem repeat (STR) expansion disorders are an important cause of human neurological disease. They have an established role in more than 40 different phenotypes including the myotonic dystrophies, Fragile X syndrome, Huntington's disease, the hereditary cerebellar ataxias, amyotrophic lateral sclerosis and frontotemporal dementia. MAIN BODY STR expansions are difficult to detect and may explain unsolved diseases, as highlighted by recent findings including: the discovery of a biallelic intronic 'AAGGG' repeat in RFC1 as the cause of cerebellar ataxia, neuropathy, and vestibular areflexia syndrome (CANVAS); and the finding of 'CGG' repeat expansions in NOTCH2NLC as the cause of neuronal intranuclear inclusion disease and a range of clinical phenotypes. However, established laboratory techniques for diagnosis of repeat expansions (repeat-primed PCR and Southern blot) are cumbersome, low-throughput and poorly suited to parallel analysis of multiple gene regions. While next generation sequencing (NGS) has been increasingly used, established short-read NGS platforms (e.g., Illumina) are unable to genotype large and/or complex repeat expansions. Long-read sequencing platforms recently developed by Oxford Nanopore Technology and Pacific Biosciences promise to overcome these limitations to deliver enhanced diagnosis of repeat expansion disorders in a rapid and cost-effective fashion. CONCLUSION We anticipate that long-read sequencing will rapidly transform the detection of short tandem repeat expansion disorders for both clinical diagnosis and gene discovery.
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Affiliation(s)
- Sanjog R. Chintalaphani
- School of Medicine, University of New South Wales, Sydney, 2052 Australia
- Kinghorn Centre for Clinical Genomics, Garvan Institute of Medical Research, Darlinghurst, NSW 2010 Australia
| | - Sandy S. Pineda
- Garvan-Weizmann Centre for Cellular Genomics, Garvan Institute of Medical Research, Darlinghurst, NSW 2010 Australia
- Brain and Mind Centre, University of Sydney, Camperdown, NSW 2050 Australia
| | - Ira W. Deveson
- Kinghorn Centre for Clinical Genomics, Garvan Institute of Medical Research, Darlinghurst, NSW 2010 Australia
- Faculty of Medicine, St Vincent’s Clinical School, University of New South Wales, Sydney, NSW 2010 Australia
| | - Kishore R. Kumar
- Kinghorn Centre for Clinical Genomics, Garvan Institute of Medical Research, Darlinghurst, NSW 2010 Australia
- Molecular Medicine Laboratory and Neurology Department, Central Clinical School, Concord Repatriation General Hospital, University of Sydney, Concord, NSW 2137 Australia
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DeJesus-Hernandez M, Aleff RA, Jackson JL, Finch NA, Baker MC, Gendron TF, Murray ME, McLaughlin IJ, Harting JR, Graff-Radford NR, Oskarsson B, Knopman DS, Josephs KA, Boeve BF, Petersen RC, Fryer JD, Petrucelli L, Dickson DW, Rademakers R, Ebbert MTW, Wieben ED, van Blitterswijk M. Long-read targeted sequencing uncovers clinicopathological associations for C9orf72-linked diseases. Brain 2021; 144:1082-1088. [PMID: 33889947 PMCID: PMC8105038 DOI: 10.1093/brain/awab006] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 10/13/2020] [Accepted: 10/30/2020] [Indexed: 11/14/2022] Open
Abstract
To examine the length of a hexanucleotide expansion in C9orf72, which represents the most frequent genetic cause of frontotemporal lobar degeneration and motor neuron disease, we employed a targeted amplification-free long-read sequencing technology: No-Amp sequencing. In our cross-sectional study, we assessed cerebellar tissue from 28 well-characterized C9orf72 expansion carriers. We obtained 3507 on-target circular consensus sequencing reads, of which 814 bridged the C9orf72 repeat expansion (23%). Importantly, we observed a significant correlation between expansion sizes obtained using No-Amp sequencing and Southern blotting (P = 5.0 × 10-4). Interestingly, we also detected a significant survival advantage for individuals with smaller expansions (P = 0.004). Additionally, we uncovered that smaller expansions were significantly associated with higher levels of C9orf72 transcripts containing intron 1b (P = 0.003), poly(GP) proteins (P = 1.3 × 10- 5), and poly(GA) proteins (P = 0.005). Thorough examination of the composition of the expansion revealed that its GC content was extremely high (median: 100%) and that it was mainly composed of GGGGCC repeats (median: 96%), suggesting that expanded C9orf72 repeats are quite pure. Taken together, our findings demonstrate that No-Amp sequencing is a powerful tool that enables the discovery of relevant clinicopathological associations, highlighting the important role played by the cerebellar size of the expanded repeat in C9orf72-linked diseases.
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Affiliation(s)
| | - Ross A Aleff
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN 55905, USA
| | - Jazmyne L Jackson
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224, USA
| | - NiCole A Finch
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224, USA
| | - Matthew C Baker
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224, USA
| | - Tania F Gendron
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224, USA
| | - Melissa E Murray
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224, USA
| | - Ian J McLaughlin
- Pacific Biosciences of California, Inc., Menlo Park, CA 94025, USA
| | - John R Harting
- Pacific Biosciences of California, Inc., Menlo Park, CA 94025, USA
| | | | - Björn Oskarsson
- Department of Neurology, Mayo Clinic, Jacksonville, FL 32224, USA
| | - David S Knopman
- Department of Neurology, Mayo Clinic, Rochester, MN 55905, USA
| | - Keith A Josephs
- Department of Neurology, Mayo Clinic, Rochester, MN 55905, USA
| | - Bradley F Boeve
- Department of Neurology, Mayo Clinic, Rochester, MN 55905, USA
| | | | - John D Fryer
- Department of Neuroscience, Mayo Clinic, Scottsdale, AZ 85259, USA
| | | | - Dennis W Dickson
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224, USA
| | - Rosa Rademakers
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224, USA
| | - Mark T W Ebbert
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224, USA
| | - Eric D Wieben
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN 55905, USA
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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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Donaldson J, Powell S, Rickards N, Holmans P, Jones L. What is the Pathogenic CAG Expansion Length in Huntington's Disease? J Huntingtons Dis 2021; 10:175-202. [PMID: 33579866 PMCID: PMC7990448 DOI: 10.3233/jhd-200445] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Huntington's disease (HD) (OMIM 143100) is caused by an expanded CAG repeat tract in the HTT gene. The inherited CAG length is known to expand further in somatic and germline cells in HD subjects. Age at onset of the disease is inversely correlated with the inherited CAG length, but is further modulated by a series of genetic modifiers which are most likely to act on the CAG repeat in HTT that permit it to further expand. Longer repeats are more prone to expansions, and this expansion is age dependent and tissue-specific. Given that the inherited tract expands through life and most subjects develop disease in mid-life, this implies that in cells that degenerate, the CAG length is likely to be longer than the inherited length. These findings suggest two thresholds- the inherited CAG length which permits further expansion, and the intracellular pathogenic threshold, above which cells become dysfunctional and die. This two-step mechanism has been previously proposed and modelled mathematically to give an intracellular pathogenic threshold at a tract length of 115 CAG (95% confidence intervals 70- 165 CAG). Empirically, the intracellular pathogenic threshold is difficult to determine. Clues from studies of people and models of HD, and from other diseases caused by expanded repeat tracts, place this threshold between 60- 100 CAG, most likely towards the upper part of that range. We assess this evidence and discuss how the intracellular pathogenic threshold in manifest disease might be better determined. Knowing the cellular pathogenic threshold would be informative for both understanding the mechanism in HD and deploying treatments.
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Affiliation(s)
- Jasmine Donaldson
- MRC Centre for Neuropsychiatric Genetics and Genomics, School of Medicine, Cardiff University, Cardiff, UK
| | - Sophie Powell
- MRC Centre for Neuropsychiatric Genetics and Genomics, School of Medicine, Cardiff University, Cardiff, UK
| | - Nadia Rickards
- MRC Centre for Neuropsychiatric Genetics and Genomics, School of Medicine, Cardiff University, Cardiff, UK
| | - Peter Holmans
- MRC Centre for Neuropsychiatric Genetics and Genomics, School of Medicine, Cardiff University, Cardiff, UK
| | - Lesley Jones
- MRC Centre for Neuropsychiatric Genetics and Genomics, School of Medicine, Cardiff University, Cardiff, UK
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Ciosi M, Cumming SA, Chatzi A, Larson E, Tottey W, Lomeikaite V, Hamilton G, Wheeler VC, Pinto RM, Kwak S, Morton AJ, Monckton DG. Approaches to Sequence the HTT CAG Repeat Expansion and Quantify Repeat Length Variation. J Huntingtons Dis 2021; 10:53-74. [PMID: 33579864 PMCID: PMC7990409 DOI: 10.3233/jhd-200433] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
BACKGROUND Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder caused by the expansion of the HTT CAG repeat. Affected individuals inherit ≥36 repeats and longer alleles cause earlier onset, greater disease severity and faster disease progression. The HTT CAG repeat is genetically unstable in the soma in a process that preferentially generates somatic expansions, the proportion of which is associated with disease onset, severity and progression. Somatic mosaicism of the HTT CAG repeat has traditionally been assessed by semi-quantitative PCR-electrophoresis approaches that have limitations (e.g., no information about sequence variants). Genotyping-by-sequencing could allow for some of these limitations to be overcome. OBJECTIVE To investigate the utility of PCR sequencing to genotype large (>50 CAGs) HD alleles and to quantify the associated somatic mosaicism. METHODS We have applied MiSeq and PacBio sequencing to PCR products of the HTT CAG repeat in transgenic R6/2 mice carrying ∼55, ∼110, ∼255 and ∼470 CAGs. For each of these alleles, we compared the repeat length distributions generated for different tissues at two ages. RESULTS We were able to sequence the CAG repeat full length in all samples. However, the repeat length distributions for samples with ∼470 CAGs were biased towards shorter repeat lengths. CONCLUSION PCR sequencing can be used to sequence all the HD alleles considered, but this approach cannot be used to estimate modal allele size or quantify somatic expansions for alleles ⪢250 CAGs. We review the limitations of PCR sequencing and alternative approaches that may allow the quantification of somatic contractions and very large somatic expansions.
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Affiliation(s)
- Marc Ciosi
- 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
| | - Afroditi Chatzi
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Eloise Larson
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - William Tottey
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Vilija Lomeikaite
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Graham Hamilton
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
- Glasgow Polyomics, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Vanessa C. Wheeler
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA
- Department of Neurology, Harvard Medical School, Boston, MA, USA
| | - Ricardo Mouro Pinto
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA
- Department of Neurology, Harvard Medical School, Boston, MA, USA
| | - Seung Kwak
- CHDI Management/CHDI Foundation, Princeton, NJ, USA
| | - A. Jennifer Morton
- Department of Physiology, Development and Neuroscience, University of Cambridge, Tennis Court Road, Cambridge, UK
| | - Darren G. Monckton
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
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35
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Affiliation(s)
- Jan M Friedman
- Department of Medical Genetics, University of British Columbia, Vancouver, Canada
| | | | - John C Carey
- Department of Pediatrics, University of Utah Health, Salt Lake City
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Höijer I, Johansson J, Gudmundsson S, Chin CS, Bunikis I, Häggqvist S, Emmanouilidou A, Wilbe M, den Hoed M, Bondeson ML, Feuk L, Gyllensten U, Ameur A. Amplification-free long-read sequencing reveals unforeseen CRISPR-Cas9 off-target activity. Genome Biol 2020; 21:290. [PMID: 33261648 PMCID: PMC7706270 DOI: 10.1186/s13059-020-02206-w] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Accepted: 11/17/2020] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND One ongoing concern about CRISPR-Cas9 genome editing is that unspecific guide RNA (gRNA) binding may induce off-target mutations. However, accurate prediction of CRISPR-Cas9 off-target activity is challenging. Here, we present SMRT-OTS and Nano-OTS, two novel, amplification-free, long-read sequencing protocols for detection of gRNA-driven digestion of genomic DNA by Cas9 in vitro. RESULTS The methods are assessed using the human cell line HEK293, re-sequenced at 18x coverage using highly accurate HiFi SMRT reads. SMRT-OTS and Nano-OTS are first applied to three different gRNAs targeting HEK293 genomic DNA, resulting in a set of 55 high-confidence gRNA cleavage sites identified by both methods. Twenty-five of these sites are not reported by off-target prediction software, either because they contain four or more single nucleotide mismatches or insertion/deletion mismatches, as compared with the human reference. Additional experiments reveal that 85% of Cas9 cleavage sites are also found by other in vitro-based methods and that on- and off-target sites are detectable in gene bodies where short-reads fail to uniquely align. Even though SMRT-OTS and Nano-OTS identify several sites with previously validated off-target editing activity in cells, our own CRISPR-Cas9 editing experiments in human fibroblasts do not give rise to detectable off-target mutations at the in vitro-predicted sites. However, indel and structural variation events are enriched at the on-target sites. CONCLUSIONS Amplification-free long-read sequencing reveals Cas9 cleavage sites in vitro that would have been difficult to predict using computational tools, including in dark genomic regions inaccessible by short-read sequencing.
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Affiliation(s)
- Ida Höijer
- Science for Life Laboratory, Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
| | - Josefin Johansson
- Science for Life Laboratory, Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
| | - Sanna Gudmundsson
- Science for Life Laboratory, Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
- Program in Medical and Population Genetics, Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, MA USA
- Division of Genetics and Genomics, Boston Children’s Hospital, Boston, MA USA
| | | | - Ignas Bunikis
- Science for Life Laboratory, Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
| | - Susana Häggqvist
- Science for Life Laboratory, Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
| | - Anastasia Emmanouilidou
- Science for Life Laboratory, Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
- The Beijer laboratory and Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
| | - Maria Wilbe
- Science for Life Laboratory, Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
| | - Marcel den Hoed
- Science for Life Laboratory, Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
- The Beijer laboratory and Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
| | - Marie-Louise Bondeson
- Science for Life Laboratory, Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
| | - Lars Feuk
- Science for Life Laboratory, Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
| | - Ulf Gyllensten
- Science for Life Laboratory, Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
| | - Adam Ameur
- Science for Life Laboratory, Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
- Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, Australia
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37
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Affiliation(s)
- Adam Ameur
- Science for Life Laboratory, Department of Immunology, Genetics and Pathology, Uppsala University, Sweden; and Monash University, Melbourne, Australia.,Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, Australia
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Madsen EB, Höijer I, Kvist T, Ameur A, Mikkelsen MJ. Xdrop: Targeted sequencing of long DNA molecules from low input samples using droplet sorting. Hum Mutat 2020; 41:1671-1679. [PMID: 32516842 PMCID: PMC7496172 DOI: 10.1002/humu.24063] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Revised: 04/29/2020] [Accepted: 06/05/2020] [Indexed: 11/07/2022]
Abstract
Long-read sequencing can resolve regions of the genome that are inaccessible to short reads, and therefore are ideal for genome-gap closure, solving structural rearrangements and sequencing through repetitive elements. Here we introduce the Xdrop technology: a novel microfluidic-based system that allows for targeted enrichment of long DNA molecules starting from only a few nanograms of DNA. Xdrop is based on the isolation of long DNA fragments in millions of droplets, where the droplets containing a target sequence of interest are fluorescently labeled and sorted using flow cytometry. The final product from the Xdrop procedure is an enriched population of long DNA molecules that can be investigated by sequencing. To demonstrate the capability of Xdrop, we performed enrichment of the human papilloma virus 18 integrated into the genome of human HeLa cells. Analysis of the sequencing reads resolved three HPV18-chr8 integrations at base-pair resolution, and the captured fragments extended up to 30 kb into the human genome at the integration sites. Further, we enriched the complete TP53 locus in a leukemia cell line and could successfully phase coexisting mutations using PacBio sequencing. In summary, our results show that Xdrop is an efficient enrichment technology for studying complex genomic regions.
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Affiliation(s)
| | - Ida Höijer
- Science for Life Laboratory, Department of Immunology, Genetics and PathologyUppsala UniversityUppsalaSweden
| | | | - Adam Ameur
- Science for Life Laboratory, Department of Immunology, Genetics and PathologyUppsala UniversityUppsalaSweden
- Department of Epidemiology and Preventive MedicineMonash UniversityMelbourneAustralia
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CRISPR/Cas9 novel therapeutic road for the treatment of neurodegenerative diseases. Life Sci 2020; 259:118165. [PMID: 32735884 DOI: 10.1016/j.lfs.2020.118165] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 07/19/2020] [Accepted: 07/26/2020] [Indexed: 02/06/2023]
Abstract
CRISPR (clustered regularly interspaced short palindromic Repeats)/Cas9 is a new genetic editing technology that can be a beneficial method to advance gene therapy. CRISPR technology is a defense system of some bacteria against invading viruses. Genome editing based on the CRISPR/Cas9 system is an efficient and potential technology that can be a viable alternative to traditional methods. This system is a compound of a short guide RNAs (gRNAs) for identifying the target DNA sequence and Cas9 protein as nuclease for breaking and cutting of DNA. In this review, recent advances in the CRISPR/Cas9-mediated genome editing tools are presented as well as their use in gene therapy strategies for the treatment of neurological disorders including Parkinson's disease, Alzheimer's disease, and Huntington's disease.
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Fautsch MP, Wieben ED, Baratz KH, Bhattacharyya N, Sadan AN, Hafford-Tear NJ, Tuft SJ, Davidson AE. TCF4-mediated Fuchs endothelial corneal dystrophy: Insights into a common trinucleotide repeat-associated disease. Prog Retin Eye Res 2020; 81:100883. [PMID: 32735996 PMCID: PMC7988464 DOI: 10.1016/j.preteyeres.2020.100883] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 06/24/2020] [Accepted: 07/04/2020] [Indexed: 12/13/2022]
Abstract
Fuchs endothelial corneal dystrophy (FECD) is a common cause for heritable visual loss in the elderly. Since the first description of an association between FECD and common polymorphisms situated within the transcription factor 4 (TCF4) gene, genetic and molecular studies have implicated an intronic CTG trinucleotide repeat (CTG18.1) expansion as a causal variant in the majority of FECD patients. To date, several non-mutually exclusive mechanisms have been proposed that drive and/or exacerbate the onset of disease. These mechanisms include (i) TCF4 dysregulation; (ii) toxic gain-of-function from TCF4 repeat-containing RNA; (iii) toxic gain-of-function from repeat-associated non-AUG dependent (RAN) translation; and (iv) somatic instability of CTG18.1. However, the relative contribution of these proposed mechanisms in disease pathogenesis is currently unknown. In this review, we summarise research implicating the repeat expansion in disease pathogenesis, define the phenotype-genotype correlations between FECD and CTG18.1 expansion, and provide an update on research tools that are available to study FECD as a trinucleotide repeat expansion disease. Furthermore, ongoing international research efforts to develop novel CTG18.1 expansion-mediated FECD therapeutics are highlighted and we provide a forward-thinking perspective on key unanswered questions that remain in the field. FECD is a common, age-related corneal dystrophy. The majority of cases are associated with expansion of a CTG repeat (CTG18.1). FECD is the most common trinucleotide repeat expansion disease in humans. Evidence supports multiple molecular mechanisms underlying the pathophysiology. Novel CTG18.1-targeted therapeutics are in development.
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Affiliation(s)
- Michael P Fautsch
- Department of Ophthalmology, 200 1st St SW, Mayo Clinic, Rochester, MN, 55905, USA.
| | - Eric D Wieben
- Department of Biochemistry and Molecular Biology, 200 1st St SW, Mayo Clinic, Rochester, MN, USA.
| | - Keith H Baratz
- Department of Ophthalmology, 200 1st St SW, Mayo Clinic, Rochester, MN, 55905, USA.
| | | | - Amanda N Sadan
- University College London Institute of Ophthalmology, London, ECIV 9EL, UK.
| | | | - Stephen J Tuft
- University College London Institute of Ophthalmology, London, ECIV 9EL, UK; Moorfields Eye Hospital, London, EC1V 2PD, UK.
| | - Alice E Davidson
- University College London Institute of Ophthalmology, London, ECIV 9EL, UK.
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Lalonde E, Rentas S, Lin F, Dulik MC, Skraban CM, Spinner NB. Genomic Diagnosis for Pediatric Disorders: Revolution and Evolution. Front Pediatr 2020; 8:373. [PMID: 32733828 PMCID: PMC7360789 DOI: 10.3389/fped.2020.00373] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Accepted: 06/02/2020] [Indexed: 12/14/2022] Open
Abstract
Powerful, recent advances in technologies to analyze the genome have had a profound impact on the practice of medical genetics, both in the laboratory and in the clinic. Increasing utilization of genome-wide testing such as chromosomal microarray analysis and exome sequencing have lead a shift toward a "genotype-first" approach. Numerous techniques are now available to diagnose a particular syndrome or phenotype, and while traditional techniques remain efficient tools in certain situations, higher-throughput technologies have become the de facto laboratory tool for diagnosis of most conditions. However, selecting the right assay or technology is challenging, and the wrong choice may lead to prolonged time to diagnosis, or even a missed diagnosis. In this review, we will discuss current core technologies for the diagnosis of classic genetic disorders to shed light on the benefits and disadvantages of these strategies, including diagnostic efficiency, variant interpretation, and secondary findings. Finally, we review upcoming technologies posed to impart further changes in the field of genetic diagnostics as we move toward "genome-first" practice.
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Affiliation(s)
- Emilie Lalonde
- Division of Genomic Diagnostics, Department of Pathology and Laboratory Medicine, School of Medicine, Children's Hospital of Philadelphia, University of Pennsylvania, Philadelphia, PA, United States
| | - Stefan Rentas
- Division of Genomic Diagnostics, Department of Pathology and Laboratory Medicine, School of Medicine, Children's Hospital of Philadelphia, University of Pennsylvania, Philadelphia, PA, United States
| | - Fumin Lin
- Division of Genomic Diagnostics, Department of Pathology and Laboratory Medicine, School of Medicine, Children's Hospital of Philadelphia, University of Pennsylvania, Philadelphia, PA, United States
| | - Matthew C. Dulik
- Division of Genomic Diagnostics, Department of Pathology and Laboratory Medicine, School of Medicine, Children's Hospital of Philadelphia, University of Pennsylvania, Philadelphia, PA, United States
| | - Cara M. Skraban
- Division of Human Genetics, Department of Pediatrics, School of Medicine, Children's Hospital of Philadelphia, University of Pennsylvania, Philadelphia, PA, United States
| | - Nancy B. Spinner
- Division of Genomic Diagnostics, Department of Pathology and Laboratory Medicine, School of Medicine, Children's Hospital of Philadelphia, University of Pennsylvania, Philadelphia, PA, United States
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Abstract
Genomic sequencing technologies have revolutionized mutation detection of the genetic diseases in the past few years. In recent years, the third generation sequencing (TGS) has been gaining insight into more genetic diseases owing to the single molecular and real time sequencing technology. This paper reviews the genomic sequencing revolutionary history first and then focuses on the genetic diseases discovered through the TGS and the clinical effects of the TGS, which is followed by the discussion of the improvement in the bioinformatic analysis for the TGS and its limitations. In summary, the TGS has been enhancing the diagnostic accuracy of genetic diseases in molecular level as well as paving a new way for basic researches and therapies.
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Affiliation(s)
- Tiantian Xiao
- Clinic of Neonatology, Children's Hospital of Fudan University, Shanghai 201102, China.,Department of Neonatology, Chengdu Women's and Children's Central Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu 611731, China
| | - Wenhao Zhou
- Clinic of Neonatology, Children's Hospital of Fudan University, Shanghai 201102, China.,Key Laboratory of Birth Defects, Children's Hospital of Fudan University, Shanghai 201102, China.,Key Laboratory of Neonatal Diseases, Children's Hospital of Fudan University, Shanghai 201102, China
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43
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Balachandran P, Beck CR. Structural variant identification and characterization. Chromosome Res 2020; 28:31-47. [PMID: 31907725 PMCID: PMC7131885 DOI: 10.1007/s10577-019-09623-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 10/15/2019] [Accepted: 11/24/2019] [Indexed: 01/06/2023]
Abstract
Structural variant (SV) differences between human genomes can cause germline and mosaic disease as well as inter-individual variation. De-regulation of accurate DNA repair and genomic surveillance mechanisms results in a large number of SVs in cancer. Analysis of the DNA sequences at SV breakpoints can help identify pathways of mutagenesis and regions of the genome that are more susceptible to rearrangement. Large-scale SV analyses have been enabled by high-throughput genome-level sequencing on humans in the past decade. These studies have shed light on the mechanisms and prevalence of complex genomic rearrangements. Recent advancements in both sequencing and other mapping technologies as well as calling algorithms for detection of genomic rearrangements have helped propel SV detection into population-scale studies, and have begun to elucidate previously inaccessible regions of the genome. Here, we discuss the genomic organization of simple and complex SVs, the molecular mechanisms of their formation, and various ways to detect them. We also introduce methods for characterizing SVs and their consequences on human genomes.
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Affiliation(s)
| | - Christine R Beck
- The Jackson Laboratory for Genomic Medicine, Farmington, CT, 06032, USA.
- Department of Genetics and Genome Sciences, Institute for Systems Genomics, University of Connecticut Health Center, Farmington, CT, 06030, USA.
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44
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Chiara M, Zambelli F, Picardi E, Horner DS, Pesole G. Critical assessment of bioinformatics methods for the characterization of pathological repeat expansions with single-molecule sequencing data. Brief Bioinform 2019; 21:1971-1986. [DOI: 10.1093/bib/bbz099] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Revised: 06/22/2019] [Accepted: 07/09/2019] [Indexed: 01/19/2023] Open
Abstract
Abstract
A number of studies have reported the successful application of single-molecule sequencing technologies to the determination of the size and sequence of pathological expanded microsatellite repeats over the last 5 years. However, different custom bioinformatics pipelines were employed in each study, preventing meaningful comparisons and somewhat limiting the reproducibility of the results. In this review, we provide a brief summary of state-of-the-art methods for the characterization of expanded repeats alleles, along with a detailed comparison of bioinformatics tools for the determination of repeat length and sequence, using both real and simulated data. Our reanalysis of publicly available human genome sequencing data suggests a modest, but statistically significant, increase of the error rate of single-molecule sequencing technologies at genomic regions containing short tandem repeats. However, we observe that all the methods herein tested, irrespective of the strategy used for the analysis of the data (either based on the alignment or assembly of the reads), show high levels of sensitivity in both the detection of expanded tandem repeats and the estimation of the expansion size, suggesting that approaches based on single-molecule sequencing technologies are highly effective for the detection and quantification of tandem repeat expansions and contractions.
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Affiliation(s)
- Matteo Chiara
- Department of Biosciences, University of Milan, via Celoria 26, 20133 Milan, Italy
- Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies, National Research Council, Via Amendola e, 70126 Bari, Italy
| | - Federico Zambelli
- Department of Biosciences, University of Milan, via Celoria 26, 20133 Milan, Italy
- Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies, National Research Council, Via Amendola e, 70126 Bari, Italy
| | - Ernesto Picardi
- Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies, National Research Council, Via Amendola e, 70126 Bari, Italy
- Department of Biosciences, Biotechnology and Biopharmaceutics, University of Bari “A. Moro”, Via Orabona 4, 70126 Bari, Italy
| | - David S Horner
- Department of Biosciences, University of Milan, via Celoria 26, 20133 Milan, Italy
- Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies, National Research Council, Via Amendola e, 70126 Bari, Italy
| | - Graziano Pesole
- Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies, National Research Council, Via Amendola e, 70126 Bari, Italy
- Department of Biosciences, Biotechnology and Biopharmaceutics, University of Bari “A. Moro”, Via Orabona 4, 70126 Bari, Italy
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45
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Long-read sequencing for rare human genetic diseases. J Hum Genet 2019; 65:11-19. [PMID: 31558760 DOI: 10.1038/s10038-019-0671-8] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Revised: 08/28/2019] [Accepted: 09/03/2019] [Indexed: 12/19/2022]
Abstract
During the past decade, the search for pathogenic mutations in rare human genetic diseases has involved huge efforts to sequence coding regions, or the entire genome, using massively parallel short-read sequencers. However, the approximate current diagnostic rate is <50% using these approaches, and there remain many rare genetic diseases with unknown cause. There may be many reasons for this, but one plausible explanation is that the responsible mutations are in regions of the genome that are difficult to sequence using conventional technologies (e.g., tandem-repeat expansion or complex chromosomal structural aberrations). Despite the drawbacks of high cost and a shortage of standard analytical methods, several studies have analyzed pathogenic changes in the genome using long-read sequencers. The results of these studies provide hope that further application of long-read sequencers to identify the causative mutations in unsolved genetic diseases may expand our understanding of the human genome and diseases. Such approaches may also be applied to molecular diagnosis and therapeutic strategies for patients with genetic diseases in the future.
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46
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De Coster W, Van Broeckhoven C. Newest Methods for Detecting Structural Variations. Trends Biotechnol 2019; 37:973-982. [DOI: 10.1016/j.tibtech.2019.02.003] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2018] [Revised: 02/08/2019] [Accepted: 02/11/2019] [Indexed: 01/28/2023]
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47
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Hafford-Tear NJ, Tsai YC, Sadan AN, Sanchez-Pintado B, Zarouchlioti C, Maher GJ, Liskova P, Tuft SJ, Hardcastle AJ, Clark TA, Davidson AE. CRISPR/Cas9-targeted enrichment and long-read sequencing of the Fuchs endothelial corneal dystrophy-associated TCF4 triplet repeat. Genet Med 2019; 21:2092-2102. [PMID: 30733599 PMCID: PMC6752322 DOI: 10.1038/s41436-019-0453-x] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Accepted: 01/24/2019] [Indexed: 12/15/2022] Open
Abstract
PURPOSE To demonstrate the utility of an amplification-free long-read sequencing method to characterize the Fuchs endothelial corneal dystrophy (FECD)-associated intronic TCF4 triplet repeat (CTG18.1). METHODS We applied an amplification-free method, utilizing the CRISPR/Cas9 system, in combination with PacBio single-molecule real-time (SMRT) long-read sequencing, to study CTG18.1. FECD patient samples displaying a diverse range of CTG18.1 allele lengths and zygosity status (n = 11) were analyzed. A robust data analysis pipeline was developed to effectively filter, align, and interrogate CTG18.1-specific reads. All results were compared with conventional polymerase chain reaction (PCR)-based fragment analysis. RESULTS CRISPR-guided SMRT sequencing of CTG18.1 provided accurate genotyping information for all samples and phasing was possible for 18/22 alleles sequenced. Repeat length instability was observed for all expanded (≥50 repeats) phased CTG18.1 alleles analyzed. Furthermore, higher levels of repeat instability were associated with increased CTG18.1 allele length (mode length ≥91 repeats) indicating that expanded alleles behave dynamically. CONCLUSION CRISPR-guided SMRT sequencing of CTG18.1 has revealed novel insights into CTG18.1 length instability. Furthermore, this study provides a framework to improve the molecular diagnostic accuracy for CTG18.1-mediated FECD, which we anticipate will become increasingly important as gene-directed therapies are developed for this common age-related and sight threatening disease.
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Affiliation(s)
| | | | | | | | | | - Geoffrey J Maher
- Clinical Genetics Group, MRC Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, UK
| | - Petra Liskova
- UCL Institute of Ophthalmology, London, UK
- Department of Ophthalmology, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague, Czech Republic
| | - Stephen J Tuft
- UCL Institute of Ophthalmology, London, UK
- Moorfields Eye Hospital, London, UK
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48
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Wieben ED, Aleff RA, Basu S, Sarangi V, Bowman B, McLaughlin IJ, Mills JR, Butz ML, Highsmith EW, Ida CM, Ekholm JM, Baratz KH, Fautsch MP. Amplification-free long-read sequencing of TCF4 expanded trinucleotide repeats in Fuchs Endothelial Corneal Dystrophy. PLoS One 2019; 14:e0219446. [PMID: 31276570 PMCID: PMC6611681 DOI: 10.1371/journal.pone.0219446] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2019] [Accepted: 06/24/2019] [Indexed: 11/18/2022] Open
Abstract
Amplification of a CAG trinucleotide motif (CTG18.1) within the TCF4 gene has been strongly associated with Fuchs Endothelial Corneal Dystrophy (FECD). Nevertheless, a small minority of clinically unaffected elderly patients who have expanded CTG18.1 sequences have been identified. To test the hypothesis that the CAG expansions in these patients are protected from FECD because they have interruptions within the CAG repeats, we utilized a combination of an amplification-free, long-read sequencing method and a new target-enrichment sequence analysis tool developed by Pacific Biosciences to interrogate the sequence structure of expanded repeats. The sequencing was successful in identifying a previously described interruption within an unexpanded allele and provided sequence data on expanded alleles greater than 2000 bases in length. The data revealed considerable heterogeneity in the size distribution of expanded repeats within each patient. Detailed analysis of the long sequence reads did not reveal any instances of interruptions to the expanded CAG repeats, but did reveal novel variants within the AGG repeats that flank the CAG repeats in two of the five samples from clinically unaffected patients with expansions. This first examination of the sequence structure of CAG repeats in CTG18.1 suggests that factors other than interruptions to the repeat structure account for the absence of disease in some elderly patients with repeat expansions in the TCF4 gene.
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Affiliation(s)
- Eric D. Wieben
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota, United States of America
| | - Ross A. Aleff
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota, United States of America
| | - Shubham Basu
- Division of Biostatistics and Bioinformatics and Department of Health Sciences Research, Mayo Clinic, Rochester, Minnesota, United States of America
| | - Vivekananda Sarangi
- Division of Biostatistics and Bioinformatics and Department of Health Sciences Research, Mayo Clinic, Rochester, Minnesota, United States of America
| | - Brett Bowman
- Pacific Biosciences of California, Inc., Menlo Park, CA, United States of America
| | - Ian J. McLaughlin
- Pacific Biosciences of California, Inc., Menlo Park, CA, United States of America
| | - John R. Mills
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, United States of America
| | - Malinda L. Butz
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, United States of America
| | - Edward W. Highsmith
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, United States of America
| | - Cristiane M. Ida
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, United States of America
| | - Jenny M. Ekholm
- Pacific Biosciences of California, Inc., Menlo Park, CA, United States of America
| | - Keith H. Baratz
- Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota, United States of America
| | - Michael P. Fautsch
- Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota, United States of America
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49
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Mantere T, Kersten S, Hoischen A. Long-Read Sequencing Emerging in Medical Genetics. Front Genet 2019; 10:426. [PMID: 31134132 PMCID: PMC6514244 DOI: 10.3389/fgene.2019.00426] [Citation(s) in RCA: 226] [Impact Index Per Article: 45.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Accepted: 04/18/2019] [Indexed: 12/12/2022] Open
Abstract
The wide implementation of next-generation sequencing (NGS) technologies has revolutionized the field of medical genetics. However, the short read lengths of currently used sequencing approaches pose a limitation for the identification of structural variants, sequencing repetitive regions, phasing of alleles and distinguishing highly homologous genomic regions. These limitations may significantly contribute to the diagnostic gap in patients with genetic disorders who have undergone standard NGS, like whole exome or even genome sequencing. Now, the emerging long-read sequencing (LRS) technologies may offer improvements in the characterization of genetic variation and regions that are difficult to assess with the prevailing NGS approaches. LRS has so far mainly been used to investigate genetic disorders with previously known or strongly suspected disease loci. While these targeted approaches already show the potential of LRS, it remains to be seen whether LRS technologies can soon enable true whole genome sequencing routinely. Ultimately, this could allow the de novo assembly of individual whole genomes used as a generic test for genetic disorders. In this article, we summarize the current LRS-based research on human genetic disorders and discuss the potential of these technologies to facilitate the next major advancements in medical genetics.
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Affiliation(s)
- Tuomo Mantere
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, Netherlands
- Laboratory of Cancer Genetics and Tumor Biology, Cancer and Translational Medicine Research Unit and Biocenter Oulu, University of Oulu, Oulu, Finland
| | - Simone Kersten
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, Netherlands
- Department of Internal Medicine, Center for Infectious Diseases (RCI), Radboud University Medical Center, Nijmegen, Netherlands
- Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, Netherlands
| | - Alexander Hoischen
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, Netherlands
- Department of Internal Medicine, Center for Infectious Diseases (RCI), Radboud University Medical Center, Nijmegen, Netherlands
- Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, Netherlands
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50
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Mitsuhashi S, Frith MC, Mizuguchi T, Miyatake S, Toyota T, Adachi H, Oma Y, Kino Y, Mitsuhashi H, Matsumoto N. Tandem-genotypes: robust detection of tandem repeat expansions from long DNA reads. Genome Biol 2019; 20:58. [PMID: 30890163 PMCID: PMC6425644 DOI: 10.1186/s13059-019-1667-6] [Citation(s) in RCA: 81] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Accepted: 03/01/2019] [Indexed: 01/03/2023] Open
Abstract
Tandemly repeated DNA is highly mutable and causes at least 31 diseases, but it is hard to detect pathogenic repeat expansions genome-wide. Here, we report robust detection of human repeat expansions from careful alignments of long but error-prone (PacBio and nanopore) reads to a reference genome. Our method is robust to systematic sequencing errors, inexact repeats with fuzzy boundaries, and low sequencing coverage. By comparing to healthy controls, we prioritize pathogenic expansions within the top 10 out of 700,000 tandem repeats in whole genome sequencing data. This may help to elucidate the many genetic diseases whose causes remain unknown.
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Affiliation(s)
- Satomi Mitsuhashi
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Fukuura 3-9, Kanazawa-ku, Yokohama, 236-0004, Japan.
| | - Martin C Frith
- Artificial Intelligence Research Center, National Institute of Advanced Industrial Science and Technology (AIST), 2-3-26 Aomi, Koto-ku, Tokyo, 135-0064, Japan.
- Graduate School of Frontier Sciences, University of Tokyo, Kashiwa, Chiba, Japan.
- Computational Bio Big-Data Open Innovation Laboratory (CBBD-OIL), AIST, Shinjuku-ku, Tokyo, Japan.
| | - Takeshi Mizuguchi
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Fukuura 3-9, Kanazawa-ku, Yokohama, 236-0004, Japan
| | - Satoko Miyatake
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Fukuura 3-9, Kanazawa-ku, Yokohama, 236-0004, Japan
| | - Tomoko Toyota
- Department of Neurology, University of Occupational and Environmental Health School of Medicine, Kitakyushu, Fukuoka, Japan
| | - Hiroaki Adachi
- Department of Neurology, University of Occupational and Environmental Health School of Medicine, Kitakyushu, Fukuoka, Japan
| | - Yoko Oma
- Department of Liberal Arts, Faculty of Medicine, Saitama Medical University, Iruma, Saitama, Japan
| | - Yoshihiro Kino
- Department of Bioinformatics and Molecular Neuropathology, Meiji Pharmaceutical University, Kiyose, Tokyo, Japan
| | - Hiroaki Mitsuhashi
- Department of Applied Biochemistry, School of Engineering, Tokai University, Hiratsuka, Kanagawa, Japan
| | - Naomichi Matsumoto
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Fukuura 3-9, Kanazawa-ku, Yokohama, 236-0004, Japan
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