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Tenchov R, Sasso JM, Zhou QA. Polyglutamine (PolyQ) Diseases: Navigating the Landscape of Neurodegeneration. ACS Chem Neurosci 2024. [PMID: 38996083 DOI: 10.1021/acschemneuro.4c00184] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/14/2024] Open
Abstract
Polyglutamine (polyQ) diseases are a group of inherited neurodegenerative disorders caused by expanded cytosine-adenine-guanine (CAG) repeats encoding proteins with abnormally expanded polyglutamine tract. A total of nine polyQ disorders have been identified, including Huntington's disease, six spinocerebellar ataxias, dentatorubral pallidoluysian atrophy (DRPLA), and spinal and bulbar muscular atrophy (SBMA). The diseases of this class are each considered rare, yet polyQ diseases constitute the largest group of monogenic neurodegenerative disorders. While each subtype of polyQ diseases has its own causative gene, certain pathologic molecular attributes have been implicated in virtually all of the polyQ diseases, including protein aggregation, proteolytic cleavage, neuronal dysfunction, transcription dysregulation, autophagy impairment, and mitochondrial dysfunction. Although animal models of polyQ disease are available helping to understand their pathogenesis and access disease-modifying therapies, there is neither a cure nor prevention for these diseases, with only symptomatic treatments available. In this paper, we analyze data from the CAS Content Collection to summarize the research progress in the class of polyQ diseases. We examine the publication landscape in the area in effort to provide insights into current knowledge advances and developments. We review the most discussed concepts and assess the strategies to combat these diseases. Finally, we inspect clinical applications of products against polyQ diseases with their development pipelines. The objective of this review is to provide a broad overview of the evolving landscape of current knowledge regarding the class of polyQ diseases, to outline challenges, and evaluate growth opportunities to further efforts in combating the diseases.
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Affiliation(s)
- Rumiana Tenchov
- CAS, a division of the American Chemical Society, Columbus, Ohio 43210, United States
| | - Janet M Sasso
- CAS, a division of the American Chemical Society, Columbus, Ohio 43210, United States
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Suroliya V, Uppili B, Kumar M, Jha V, Srivastava AK, Faruq M. Identifying unstable CNG repeat loci in the human genome: a heuristic approach and implications for neurological disorders. Hum Genome Var 2024; 11:25. [PMID: 38871700 DOI: 10.1038/s41439-024-00281-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Revised: 05/08/2024] [Accepted: 05/14/2024] [Indexed: 06/15/2024] Open
Abstract
Tandem nucleotide repeat (TNR) expansions, particularly the CNG nucleotide configuration, are associated with a variety of neurodegenerative disorders. In this study, we aimed to identify novel unstable CNG repeat loci associated with the neurogenetic disorder spinocerebellar ataxia (SCA). Using a computational approach, 15,069 CNG repeat loci in the coding and noncoding regions of the human genome were identified. Based on the feature selection criteria (repeat length >10 and functional location of repeats), we selected 52 repeats for further analysis and evaluated the repeat length variability in 100 control subjects. A subset of 19 CNG loci observed to be highly variable in control subjects was selected for subsequent analysis in 100 individuals with SCA. The genes with these highly variable repeats also exhibited higher gene expression levels in the brain according to the tissue expression dataset (GTEx). No pathogenic expansion events were identified in patient samples, which is a limitation given the size of the patient group examined; however, these loci contain potential risk alleles for expandability. Recent studies have implicated GLS, RAI1, GIPC1, MED15, EP400, MEF2A, and CNKSR2 in neurological diseases, with GLS, GIPC1, MED15, RAI1, and MEF2A sharing the same repeat loci reported in this study. This finding validates the approach of evaluating repeat loci in different populations and their possible implications for human pathologies.
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Affiliation(s)
- Varun Suroliya
- Department of Neurology, All India Institute of Medical Sciences, Ansari Nagar, Delhi, 110020, India
| | - Bharathram Uppili
- Genomics and Molecular Medicine, CSIR-Institute of Genomics and Integrative Biology, Mall Road, Delhi, 110007, India
- Academy for Scientific and Innovative Research, Ghaziabad, 201002, India
| | - Manish Kumar
- Genomics and Molecular Medicine, CSIR-Institute of Genomics and Integrative Biology, Mall Road, Delhi, 110007, India
- Academy for Scientific and Innovative Research, Ghaziabad, 201002, India
| | - Vineet Jha
- Persistent LABS, Persistent Systems Ltd., Pune, Maharashtra, India
| | - Achal K Srivastava
- Department of Neurology, All India Institute of Medical Sciences, Ansari Nagar, Delhi, 110020, India
| | - Mohammed Faruq
- Genomics and Molecular Medicine, CSIR-Institute of Genomics and Integrative Biology, Mall Road, Delhi, 110007, India.
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Tshilenge KT, Bons J, Aguirre CG, Geronimo-Olvera C, Shah S, Rose J, Gerencser AA, Mak SK, Ehrlich ME, Bragg DC, Schilling B, Ellerby LM. Proteomic analysis of X-linked dystonia parkinsonism disease striatal neurons reveals altered RNA metabolism and splicing. Neurobiol Dis 2024; 190:106367. [PMID: 38042508 PMCID: PMC11103251 DOI: 10.1016/j.nbd.2023.106367] [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: 09/22/2023] [Revised: 11/16/2023] [Accepted: 11/27/2023] [Indexed: 12/04/2023] Open
Abstract
X-linked dystonia-parkinsonism (XDP) is a rare neurodegenerative disease endemic to the Philippines. The genetic cause for XDP is an insertion of a SINE-VNTR-Alu (SVA)-type retrotransposon within intron 32 of TATA-binding protein associated factor 1 (TAF1) that causes an alteration of TAF1 splicing, partial intron retention, and decreased transcription. Although TAF1 is expressed in all organs, medium spiny neurons (MSNs) within the striatum are one of the cell types most affected in XDP. To define how mutations in the TAF1 gene lead to MSN vulnerability, we carried out a proteomic analysis of human XDP patient-derived neural stem cells (NSCs) and MSNs derived from induced pluripotent stem cells. NSCs and MSNs were grown in parallel and subjected to quantitative proteomic analysis in data-independent acquisition mode on the Orbitrap Eclipse Tribrid mass spectrometer. Subsequent functional enrichment analysis demonstrated that neurodegenerative disease-related pathways, such as Huntington's disease, spinocerebellar ataxia, cellular senescence, mitochondrial function and RNA binding metabolism, were highly represented. We used weighted coexpression network analysis (WGCNA) of the NSC and MSN proteomic data set to uncover disease-driving network modules. Three of the modules significantly correlated with XDP genotype when compared to the non-affected control and were enriched for DNA helicase and nuclear chromatin assembly, mitochondrial disassembly, RNA location and mRNA processing. Consistent with aberrant mRNA processing, we found splicing and intron retention of TAF1 intron 32 in XDP MSN. We also identified TAF1 as one of the top enriched transcription factors, along with YY1, ATF2, USF1 and MYC. Notably, YY1 has been implicated in genetic forms of dystonia. Overall, our proteomic data set constitutes a valuable resource to understand mechanisms relevant to TAF1 dysregulation and to identify new therapeutic targets for XDP.
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Affiliation(s)
| | - Joanna Bons
- The Buck Institute for Research on Aging, Novato, California 94945, USA
| | - Carlos Galicia Aguirre
- The Buck Institute for Research on Aging, Novato, California 94945, USA; University of Southern California, Leonard Davis School of Gerontology, 3715 McClintock Ave, Los Angeles, CA 90893, USA
| | | | - Samah Shah
- The Buck Institute for Research on Aging, Novato, California 94945, USA
| | - Jacob Rose
- The Buck Institute for Research on Aging, Novato, California 94945, USA
| | - Akos A Gerencser
- The Buck Institute for Research on Aging, Novato, California 94945, USA
| | - Sally K Mak
- The Buck Institute for Research on Aging, Novato, California 94945, USA
| | - Michelle E Ehrlich
- Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - D Cristopher Bragg
- Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA; Department of Neurology, The Collaborative Center for X-linked Dystonia-Parkinsonism, Massachusetts General Hospital, Charlestown, MA, USA
| | - Birgit Schilling
- The Buck Institute for Research on Aging, Novato, California 94945, USA; University of Southern California, Leonard Davis School of Gerontology, 3715 McClintock Ave, Los Angeles, CA 90893, USA.
| | - Lisa M Ellerby
- The Buck Institute for Research on Aging, Novato, California 94945, USA; University of Southern California, Leonard Davis School of Gerontology, 3715 McClintock Ave, Los Angeles, CA 90893, USA.
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Adam H, Gopinath SCB, Arshad MKM, Adam T, Subramaniam S, Hashim U. An Update on Parkinson's Disease and its Neurodegenerative Counterparts. Curr Med Chem 2024; 31:2770-2787. [PMID: 37016529 DOI: 10.2174/0929867330666230403085733] [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: 11/23/2022] [Revised: 01/26/2023] [Accepted: 02/10/2023] [Indexed: 04/06/2023]
Abstract
INTRODUCTION Neurodegenerative disorders are a group of diseases that cause nerve cell degeneration in the brain, resulting in a variety of symptoms and are not treatable with drugs. Parkinson's disease (PD), prion disease, motor neuron disease (MND), Huntington's disease (HD), spinal cerebral dyskinesia (SCA), spinal muscle atrophy (SMA), multiple system atrophy, Alzheimer's disease (AD), spinocerebellar ataxia (SCA) (ALS), pantothenate kinase-related neurodegeneration, and TDP-43 protein disorder are examples of neurodegenerative diseases. Dementia is caused by the loss of brain and spinal cord nerve cells in neurodegenerative diseases. BACKGROUND Even though environmental and genetic predispositions have also been involved in the process, redox metal abuse plays a crucial role in neurodegeneration since the preponderance of symptoms originates from abnormal metal metabolism. METHOD Hence, this review investigates several neurodegenerative diseases that may occur symptoms similar to Parkinson's disease to understand the differences and similarities between Parkinson's disease and other neurodegenerative disorders based on reviewing previously published papers. RESULTS Based on the findings, the aggregation of alpha-synuclein occurs in Parkinson's disease, multiple system atrophy, and dementia with Lewy bodies. Other neurodegenerative diseases occur with different protein aggregation or mutations. CONCLUSION We can conclude that Parkinson's disease, Multiple system atrophy, and Dementia with Lewy bodies are closely related. Therefore, researchers must distinguish among the three diseases to avoid misdiagnosis of Multiple System Atrophy and Dementia with Lewy bodies with Parkinson's disease symptoms.
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Affiliation(s)
- Hussaini Adam
- Institute of Nano Electronic Engineering, Universiti Malaysia Perlis (UniMAP), 01000, Kangar, Perlis, Malaysia
| | - Subash C B Gopinath
- Faculty of Chemical Engineering & Technology, Universiti Malaysia Perlis (UniMAP), 02600, Arau, Perlis, Malaysia
- Institute of Nano Electronic Engineering, Universiti Malaysia Perlis (UniMAP), 01000, Kangar, Perlis, Malaysia
- Micro System Technology, Centre of Excellence (CoE), Universiti Malaysia Perlis (UniMAP), Pauh Campus, 02600, Arau, Perlis, Malaysia
- Centre for Chemical Biology (CCB), Universiti Sains Malaysia, Bayan Lepas, 11900 Penang, Malaysia
| | - M K Md Arshad
- Institute of Nano Electronic Engineering, Universiti Malaysia Perlis (UniMAP), 01000, Kangar, Perlis, Malaysia
- Faculty of Electronic Engineering & Technology, Universiti Malaysia Perlis (UniMAP), Pauh Campus, 02600 Arau, Perlis, Malaysia
| | - Tijjani Adam
- Institute of Nano Electronic Engineering, Universiti Malaysia Perlis (UniMAP), 01000, Kangar, Perlis, Malaysia
- Faculty of Electronic Engineering & Technology, Universiti Malaysia Perlis (UniMAP), Pauh Campus, 02600 Arau, Perlis, Malaysia
- Micro System Technology, Centre of Excellence (CoE), Universiti Malaysia Perlis (UniMAP), Pauh Campus, 02600, Arau, Perlis, Malaysia
| | - Sreeramanan Subramaniam
- School of Biological Sciences, Universiti Sains Malaysia, Georgetown, 11800 Penang, Malaysia
- Faculty of Chemical Engineering & Technology, Universiti Malaysia Perlis (UniMAP), 02600, Arau, Perlis, Malaysia
- Centre for Chemical Biology (CCB), Universiti Sains Malaysia, Bayan Lepas, 11900 Penang, Malaysia
- National Poison Centre, Universiti Sains Malaysia (USM), Georgetown, 11800, Penang, Malaysia
| | - Uda Hashim
- Institute of Nano Electronic Engineering, Universiti Malaysia Perlis (UniMAP), 01000, Kangar, Perlis, Malaysia
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Lenahan AL, Squire AE, Miller DE. Panels, Exomes, Genomes, and More-Finding the Best Path Through the Diagnostic Odyssey. Pediatr Clin North Am 2023; 70:905-916. [PMID: 37704349 DOI: 10.1016/j.pcl.2023.06.001] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 09/15/2023]
Abstract
Selecting the ideal test to evaluate an individual with a suspected genetic disorder can be challenging. While several clinical testing options are available, no single test yet captures all potentially causative genetic variants. Thus, clinicians may order testing in a stepwise fashion, and what to order after non-diagnostic testing can be challenging to determine. Here, we provide an overview of commonly used clinical genetic tests, guidance on when they are best used, and what they may miss. We conclude with a discussion of how new technologies might be used to identify challenging variants and simplify clinical testing in the future.
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Affiliation(s)
- Arthur L Lenahan
- Division of Genetic Medicine, Department of Pediatrics, University of Washington and Seattle Children's Hospital, 4800 Sand Point Way, Seattle, WA 98105, USA
| | - Audrey E Squire
- Division of Genetic Medicine, Department of Pediatrics, University of Washington and Seattle Children's Hospital, 4800 Sand Point Way, Seattle, WA 98105, USA
| | - Danny E Miller
- Division of Genetic Medicine, Department of Pediatrics, University of Washington and Seattle Children's Hospital, 4800 Sand Point Way, Seattle, WA 98105, USA; Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, USA.
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Burgunder JM. Mechanisms underlying phenotypic variation in neurogenetic disorders. Nat Rev Neurol 2023:10.1038/s41582-023-00811-4. [PMID: 37202496 DOI: 10.1038/s41582-023-00811-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/12/2023] [Indexed: 05/20/2023]
Abstract
Neurological diseases associated with pathogenic variants in a specific gene, or even with a specific pathogenic variant, can show profound phenotypic variation with regard to symptom presentation, age at onset and disease course. Highlighting examples from a range of neurogenetic disorders, this Review explores emerging mechanisms that are involved in this variability, including environmental, genetic and epigenetic factors that influence the expressivity and penetrance of pathogenic variants. Environmental factors, some of which can potentially be modified to prevent disease, include trauma, stress and metabolic changes. Dynamic patterns of pathogenic variants might explain some of the phenotypic variations, for example, in the case of disorders caused by DNA repeat expansions such as Huntington disease (HD). An important role for modifier genes has also been identified in some neurogenetic disorders, including HD, spinocerebellar ataxia and X-linked dystonia-parkinsonism. In other disorders, such as spastic paraplegia, the basis for most of the phenotypic variability remains unclear. Epigenetic factors have been implicated in disorders such as SGCE-related myoclonus-dystonia and HD. Knowledge of the mechanisms underlying phenotypic variation is already starting to influence management strategies and clinical trials for neurogenetic disorders.
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Uncovering the mechanism for aggregation in repeat expanded RNA reveals a reentrant transition. Nat Commun 2023; 14:332. [PMID: 36658112 PMCID: PMC9852226 DOI: 10.1038/s41467-023-35803-x] [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: 05/31/2022] [Accepted: 12/29/2022] [Indexed: 01/21/2023] Open
Abstract
RNA molecules aggregate under certain conditions. The resulting condensates are implicated in human neurological disorders, and can potentially be designed towards specified bulk properties in vitro. However, the mechanism for aggregation-including how aggregation properties change with sequence and environmental conditions-remains poorly understood. To address this challenge, we introduce an analytical framework based on multimer enumeration. Our approach reveals the driving force for aggregation to be the increased configurational entropy associated with the multiplicity of ways to form bonds in the aggregate. Our model uncovers rich phase behavior, including a sequence-dependent reentrant phase transition, and repeat parity-dependent aggregation. We validate our results by comparison to a complete computational enumeration of the landscape, and to previously published molecular dynamics simulations. Our work unifies and extends published results, both explaining the behavior of CAG-repeat RNA aggregates implicated in Huntington's disease, and enabling the rational design of programmable RNA condensates.
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Khan ES, Danckwardt S. Pathophysiological Role and Diagnostic Potential of R-Loops in Cancer and Beyond. Genes (Basel) 2022; 13:genes13122181. [PMID: 36553448 PMCID: PMC9777984 DOI: 10.3390/genes13122181] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Revised: 11/07/2022] [Accepted: 11/14/2022] [Indexed: 11/24/2022] Open
Abstract
R-loops are DNA-RNA hybrids that play multifunctional roles in gene regulation, including replication, transcription, transcription-replication collision, epigenetics, and preserving the integrity of the genome. The aberrant formation and accumulation of unscheduled R-loops can disrupt gene expression and damage DNA, thereby causing genome instability. Recent links between unscheduled R-loop accumulation and the abundance of proteins that modulate R-loop biogenesis have been associated with numerous human diseases, including various cancers. Although R-loops are not necessarily causative for all disease entities described to date, they can perpetuate and even exacerbate the initially disease-eliciting pathophysiology, making them structures of interest for molecular diagnostics. In this review, we discuss the (patho) physiological role of R-loops in health and disease, their surprising diagnostic potential, and state-of-the-art techniques for their detection.
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Affiliation(s)
- Essak S. Khan
- Posttranscriptional Gene Regulation, Cancer Research and Experimental Hemostasis, University Medical Center Mainz, 55131 Mainz, Germany
- Institute for Clinical Chemistry and Laboratory Medicine, University Medical Center of the Johannes Gutenberg University, 55131 Mainz, Germany
- Center for Thrombosis and Hemostasis (CTH), University Medical Center of the Johannes Gutenberg University, 55131 Mainz, Germany
- German Consortium for Translational Cancer Research (DKTK), DKFZ Frankfurt-Mainz, 60590 Frankfurt am Main, Germany
| | - Sven Danckwardt
- Posttranscriptional Gene Regulation, Cancer Research and Experimental Hemostasis, University Medical Center Mainz, 55131 Mainz, Germany
- Institute for Clinical Chemistry and Laboratory Medicine, University Medical Center of the Johannes Gutenberg University, 55131 Mainz, Germany
- Center for Thrombosis and Hemostasis (CTH), University Medical Center of the Johannes Gutenberg University, 55131 Mainz, Germany
- German Center for Cardiovascular Research (DZHK), Rhine-Main, 55131 Mainz, Germany
- Correspondence:
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Rapid and comprehensive diagnostic method for repeat expansion diseases using nanopore sequencing. NPJ Genom Med 2022; 7:62. [PMID: 36289212 PMCID: PMC9606279 DOI: 10.1038/s41525-022-00331-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Accepted: 09/30/2022] [Indexed: 11/23/2022] Open
Abstract
We developed a diagnostic method for repeat expansion diseases using a long-read sequencer to improve currently available, low throughput diagnostic methods. We employed the real-time target enrichment system of the nanopore GridION sequencer using the adaptive sampling option, in which software-based target assignment is available without prior sample enrichment, and built an analysis pipeline that prioritized the disease-causing loci. Twenty-two patients with various neurological and neuromuscular diseases, including 12 with genetically diagnosed repeat expansion diseases and 10 manifesting cerebellar ataxia, but without genetic diagnosis, were analyzed. We first sequenced the 12 molecularly diagnosed patients and accurately confirmed expanded repeats in all with uniform depth of coverage across the loci. Next, we applied our method and a conventional method to 10 molecularly undiagnosed patients. Our method corrected inaccurate diagnoses of two patients by the conventional method. Our method is superior to conventional diagnostic methods in terms of speed, accuracy, and comprehensiveness.
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Davies K, Szmulewicz DJ, Corben LA, Delatycki M, Lockhart PJ. RFC1-Related Disease. Neurol Genet 2022; 8:e200016. [PMID: 36046423 PMCID: PMC9425222 DOI: 10.1212/nxg.0000000000200016] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Accepted: 06/22/2022] [Indexed: 01/03/2023]
Abstract
In 2019, a biallelic pentanucleotide repeat expansion in the gene encoding replication factor C subunit 1 (RFC1) was reported as a cause of cerebellar ataxia with neuropathy and vestibular areflexia syndrome (CANVAS). In addition, biallelic expansions were shown to account for up to 22% of cases with late-onset ataxia. Since this discovery, the phenotypic spectrum reported to be associated with RFC1 expansions has extended beyond the initial conditions to include pure cerebellar ataxia, isolated somatosensory impairment, combinations of the 2, and parkinsonism, leading to a potentially broad differential diagnosis. Genetic studies suggest RFC1 expansions may be the most common genetic cause of ataxia and are likely underdiagnosed. This review summarizes the current molecular and clinical knowledge of RFC1-related disease, with a focus on the evaluation of recent phenotype associations and highlighting the current challenges in clinical pathways to diagnosis and molecular testing.
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Braun M, Shoshani S, Tabach Y. Transcriptome changes in DM1 patients’ tissues are governed by the RNA interference pathway. Front Mol Biosci 2022; 9:955753. [PMID: 36060259 PMCID: PMC9437208 DOI: 10.3389/fmolb.2022.955753] [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: 05/29/2022] [Accepted: 07/27/2022] [Indexed: 11/13/2022] Open
Abstract
Myotonic dystrophy type 1 (DM1) is a multisystemic disease caused by pathogenic expansions of CTG repeats. The expanded repeats are transcribed to long RNA and induce cellular toxicity. Recent studies suggest that the CUG repeats are processed by the RNA interference (RNAi) pathway to generate small interfering repeated RNA (siRNA). However, the effects of the CTG repeat-derived siRNAs remain unclear. We hypothesize that the RNAi machinery in DM1 patients generates distinct gene expression patterns that determine the disease phenotype in the individual patient. The abundance of genes with complementary repeats that are targeted by siRNAs in each tissue determines the way that the tissue is affected in DM1. We integrated and analyzed published transcriptome data from muscle, heart, and brain biopsies of DM1 patients, and revealed shared, characteristic changes that correlated with disease phenotype. These signatures are overrepresented by genes and transcription factors bearing endogenous CTG/CAG repeats and are governed by aberrant activity of the RNAi machinery, miRNAs, and a specific gain-of-function of the CTG repeats. Computational analysis of the DM1 transcriptome enhances our understanding of the complex pathophysiology of the disease and may reveal a path for cure.
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Lunev E, Karan A, Egorova T, Bardina M. Adeno-Associated Viruses for Modeling Neurological Diseases in Animals: Achievements and Prospects. Biomedicines 2022; 10:biomedicines10051140. [PMID: 35625877 PMCID: PMC9139062 DOI: 10.3390/biomedicines10051140] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2022] [Revised: 05/13/2022] [Accepted: 05/13/2022] [Indexed: 02/04/2023] Open
Abstract
Adeno-associated virus (AAV) vectors have become an attractive tool for efficient gene transfer into animal tissues. Extensively studied as the vehicles for therapeutic constructs in gene therapy, AAVs are also applied for creating animal models of human genetic disorders. Neurological disorders are challenging to model in laboratory animals by transgenesis or genome editing, at least partially due to the embryonic lethality and the timing of the disease onset. Therefore, gene transfer with AAV vectors provides a more flexible option for simulating genetic neurological disorders. Indeed, the design of the AAV expression construct allows the reproduction of various disease-causing mutations, and also drives neuron-specific expression. The natural and newly created AAV serotypes combined with various delivery routes enable differentially targeting neuronal cell types and brain areas in vivo. Moreover, the same viral vector can be used to reproduce the main features of the disorder in mice, rats, and large laboratory animals such as non-human primates. The current review demonstrates the general principles for the development and use of AAVs in modeling neurological diseases. The latest achievements in AAV-mediated modeling of the common (e.g., Alzheimer’s disease, Parkinson’s disease, ataxias, etc.) and ultra-rare disorders affecting the central nervous system are described. The use of AAVs to create multiple animal models of neurological disorders opens opportunities for studying their mechanisms, understanding the main pathological features, and testing therapeutic approaches.
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Affiliation(s)
- Evgenii Lunev
- Institute of Gene Biology, Russian Academy of Sciences, 119334 Moscow, Russia
- Marlin Biotech LLC, 354340 Sochi, Russia; (A.K.); (T.E.)
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Institute of Gene Biology, Russian Academy of Sciences, 119334 Moscow, Russia
- Correspondence: (E.L.); (M.B.)
| | - Anna Karan
- Marlin Biotech LLC, 354340 Sochi, Russia; (A.K.); (T.E.)
| | - Tatiana Egorova
- Institute of Gene Biology, Russian Academy of Sciences, 119334 Moscow, Russia
- Marlin Biotech LLC, 354340 Sochi, Russia; (A.K.); (T.E.)
| | - Maryana Bardina
- Institute of Gene Biology, Russian Academy of Sciences, 119334 Moscow, Russia
- Marlin Biotech LLC, 354340 Sochi, Russia; (A.K.); (T.E.)
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Institute of Gene Biology, Russian Academy of Sciences, 119334 Moscow, Russia
- Correspondence: (E.L.); (M.B.)
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Barbé L, Finkbeiner S. Genetic and Epigenetic Interplay Define Disease Onset and Severity in Repeat Diseases. Front Aging Neurosci 2022; 14:750629. [PMID: 35592702 PMCID: PMC9110800 DOI: 10.3389/fnagi.2022.750629] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Accepted: 03/01/2022] [Indexed: 11/13/2022] Open
Abstract
Repeat diseases, such as fragile X syndrome, myotonic dystrophy, Friedreich ataxia, Huntington disease, spinocerebellar ataxias, and some forms of amyotrophic lateral sclerosis, are caused by repetitive DNA sequences that are expanded in affected individuals. The age at which an individual begins to experience symptoms, and the severity of disease, are partially determined by the size of the repeat. However, the epigenetic state of the area in and around the repeat also plays an important role in determining the age of disease onset and the rate of disease progression. Many repeat diseases share a common epigenetic pattern of increased methylation at CpG islands near the repeat region. CpG islands are CG-rich sequences that are tightly regulated by methylation and are often found at gene enhancer or insulator elements in the genome. Methylation of CpG islands can inhibit binding of the transcriptional regulator CTCF, resulting in a closed chromatin state and gene down regulation. The downregulation of these genes leads to some disease-specific symptoms. Additionally, a genetic and epigenetic interplay is suggested by an effect of methylation on repeat instability, a hallmark of large repeat expansions that leads to increasing disease severity in successive generations. In this review, we will discuss the common epigenetic patterns shared across repeat diseases, how the genetics and epigenetics interact, and how this could be involved in disease manifestation. We also discuss the currently available stem cell and mouse models, which frequently do not recapitulate epigenetic patterns observed in human disease, and propose alternative strategies to study the role of epigenetics in repeat diseases.
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Affiliation(s)
- Lise Barbé
- Center for Systems and Therapeutics, Gladstone Institutes, San Francisco, CA, United States
- Department of Neurology, University of California, San Francisco, San Francisco, CA, United States
- Department of Physiology, University of California, San Francisco, San Francisco, CA, United States
| | - Steve Finkbeiner
- Center for Systems and Therapeutics, Gladstone Institutes, San Francisco, CA, United States
- Department of Neurology, University of California, San Francisco, San Francisco, CA, United States
- Department of Physiology, University of California, San Francisco, San Francisco, CA, United States
- *Correspondence: Steve Finkbeiner,
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Asefifeyzabadi N, Durocher G, Tshilenge KT, Alam T, Ellerby LM, Shamsi MH. PNA microprobe for label-free detection of expanded trinucleotide repeats. RSC Adv 2022; 12:7757-7761. [PMID: 35424746 PMCID: PMC8982460 DOI: 10.1039/d2ra00230b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Accepted: 03/03/2022] [Indexed: 11/28/2022] Open
Abstract
We present a PNA microprobe sensing platform to detect trinucleotide repeat mutation by electrochemical impedance spectroscopy. The microprobe platform discriminated Huntington's disease-associated CAG repeats in cell-derived total RNA with S/N 1 : 3. This sensitive, label-free, and PCR-free detection strategy may be employed in the future to develop biosensing platforms for the detection of a plethora of repeat expansion disorders.
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Affiliation(s)
- Narges Asefifeyzabadi
- School of Chemical and Biomolecular Sciences, 1245 Lincoln Dr, Southern Illinois University at Carbondale IL 62901 USA
| | - Grace Durocher
- School of Chemical and Biomolecular Sciences, 1245 Lincoln Dr, Southern Illinois University at Carbondale IL 62901 USA
| | | | - Tanimul Alam
- The Buck Institute for Research on Aging 8001 Redwood Blvd Novato CA 94945 USA
| | - Lisa M Ellerby
- The Buck Institute for Research on Aging 8001 Redwood Blvd Novato CA 94945 USA
| | - Mohtashim H Shamsi
- School of Chemical and Biomolecular Sciences, 1245 Lincoln Dr, Southern Illinois University at Carbondale IL 62901 USA
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15
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Ibañez K, Polke J, Hagelstrom RT, Dolzhenko E, Pasko D, Thomas ERA, Daugherty LC, Kasperaviciute D, Smith KR, Deans ZC, Hill S, Fowler T, Scott RH, Hardy J, Chinnery PF, Houlden H, Rendon A, Caulfield MJ, Eberle MA, Taft RJ, Tucci A. Whole genome sequencing for the diagnosis of neurological repeat expansion disorders in the UK: a retrospective diagnostic accuracy and prospective clinical validation study. Lancet Neurol 2022; 21:234-245. [PMID: 35182509 PMCID: PMC8850201 DOI: 10.1016/s1474-4422(21)00462-2] [Citation(s) in RCA: 71] [Impact Index Per Article: 35.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Revised: 11/09/2021] [Accepted: 12/14/2021] [Indexed: 01/19/2023]
Abstract
BACKGROUND Repeat expansion disorders affect about 1 in 3000 individuals and are clinically heterogeneous diseases caused by expansions of short tandem DNA repeats. Genetic testing is often locus-specific, resulting in underdiagnosis of people who have atypical clinical presentations, especially in paediatric patients without a previous positive family history. Whole genome sequencing is increasingly used as a first-line test for other rare genetic disorders, and we aimed to assess its performance in the diagnosis of patients with neurological repeat expansion disorders. METHODS We retrospectively assessed the diagnostic accuracy of whole genome sequencing to detect the most common repeat expansion loci associated with neurological outcomes (AR, ATN1, ATXN1, ATXN2, ATXN3, ATXN7, C9orf72, CACNA1A, DMPK, FMR1, FXN, HTT, and TBP) using samples obtained within the National Health Service in England from patients who were suspected of having neurological disorders; previous PCR test results were used as the reference standard. The clinical accuracy of whole genome sequencing to detect repeat expansions was prospectively examined in previously genetically tested and undiagnosed patients recruited in 2013-17 to the 100 000 Genomes Project in the UK, who were suspected of having a genetic neurological disorder (familial or early-onset forms of ataxia, neuropathy, spastic paraplegia, dementia, motor neuron disease, parkinsonian movement disorders, intellectual disability, or neuromuscular disorders). If a repeat expansion call was made using whole genome sequencing, PCR was used to confirm the result. FINDINGS The diagnostic accuracy of whole genome sequencing to detect repeat expansions was evaluated against 793 PCR tests previously performed within the NHS from 404 patients. Whole genome sequencing correctly classified 215 of 221 expanded alleles and 1316 of 1321 non-expanded alleles, showing 97·3% sensitivity (95% CI 94·2-99·0) and 99·6% specificity (99·1-99·9) across the 13 disease-associated loci when compared with PCR test results. In samples from 11 631 patients in the 100 000 Genomes Project, whole genome sequencing identified 81 repeat expansions, which were also tested by PCR: 68 were confirmed as repeat expansions in the full pathogenic range, 11 were non-pathogenic intermediate expansions or premutations, and two were non-expanded repeats (16% false discovery rate). INTERPRETATION In our study, whole genome sequencing for the detection of repeat expansions showed high sensitivity and specificity, and it led to identification of neurological repeat expansion disorders in previously undiagnosed patients. These findings support implementation of whole genome sequencing in clinical laboratories for diagnosis of patients who have a neurological presentation consistent with a repeat expansion disorder. FUNDING Medical Research Council, Department of Health and Social Care, National Health Service England, National Institute for Health Research, and Illumina.
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Affiliation(s)
- Kristina Ibañez
- Genomics England, Queen Mary University of London, London, UK; William Harvey Research Institute, Queen Mary University of London, London, UK
| | - James Polke
- Neurogenetics Unit, National Hospital for Neurology and Neurosurgery, London, UK
| | | | | | - Dorota Pasko
- Genomics England, Queen Mary University of London, London, UK
| | | | - Louise C Daugherty
- Genomics England, Queen Mary University of London, London, UK; Healx, Cambridge, UK
| | - Dalia Kasperaviciute
- Genomics England, Queen Mary University of London, London, UK; William Harvey Research Institute, Queen Mary University of London, London, UK
| | - Katherine R Smith
- Genomics England, Queen Mary University of London, London, UK; William Harvey Research Institute, Queen Mary University of London, London, UK
| | - Zandra C Deans
- Genomics Quality Assessment, Department of Laboratory Medicine, Royal Infirmary of Edinburgh, Edinburgh, UK; NHS England and NHS Improvement, London, UK
| | - Sue Hill
- NHS England and NHS Improvement, London, UK
| | - Tom Fowler
- Genomics England, Queen Mary University of London, London, UK
| | - Richard H Scott
- Genomics England, Queen Mary University of London, London, UK; Department of Genetics and Genomic Medicine, UCL Great Ormond Street Institute of Child Health, London, UK
| | - John Hardy
- Department of Neurodegenerative Disorders, Institute of Neurology, University College London, London, UK
| | - Patrick F Chinnery
- MRC Mitochondrial Biology Unit and Department of ClinicalNeurosciences, University of Cambridge, Cambridge, UK
| | - Henry Houlden
- Neurogenetics Unit, National Hospital for Neurology and Neurosurgery, London, UK; Department of Neuromuscular Diseases, Institute of Neurology, University College London, London, UK
| | - Augusto Rendon
- Genomics England, Queen Mary University of London, London, UK
| | - Mark J Caulfield
- Genomics England, Queen Mary University of London, London, UK; William Harvey Research Institute, Queen Mary University of London, London, UK
| | | | | | - Arianna Tucci
- Genomics England, Queen Mary University of London, London, UK; William Harvey Research Institute, Queen Mary University of London, London, UK.
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16
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Ibañez K, Polke J, Hagelstrom RT, Dolzhenko E, Pasko D, Thomas ERA, Daugherty LC, Kasperaviciute D, Smith KR, Deans ZC, Hill S, Fowler T, Scott RH, Hardy J, Chinnery PF, Houlden H, Rendon A, Caulfield MJ, Eberle MA, Taft RJ, Tucci A. Whole genome sequencing for the diagnosis of neurological repeat expansion disorders in the UK: a retrospective diagnostic accuracy and prospective clinical validation study. Lancet Neurol 2022. [PMID: 35182509 DOI: 10.1101/2020.11.06.371716v1.abstract] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
BACKGROUND Repeat expansion disorders affect about 1 in 3000 individuals and are clinically heterogeneous diseases caused by expansions of short tandem DNA repeats. Genetic testing is often locus-specific, resulting in underdiagnosis of people who have atypical clinical presentations, especially in paediatric patients without a previous positive family history. Whole genome sequencing is increasingly used as a first-line test for other rare genetic disorders, and we aimed to assess its performance in the diagnosis of patients with neurological repeat expansion disorders. METHODS We retrospectively assessed the diagnostic accuracy of whole genome sequencing to detect the most common repeat expansion loci associated with neurological outcomes (AR, ATN1, ATXN1, ATXN2, ATXN3, ATXN7, C9orf72, CACNA1A, DMPK, FMR1, FXN, HTT, and TBP) using samples obtained within the National Health Service in England from patients who were suspected of having neurological disorders; previous PCR test results were used as the reference standard. The clinical accuracy of whole genome sequencing to detect repeat expansions was prospectively examined in previously genetically tested and undiagnosed patients recruited in 2013-17 to the 100 000 Genomes Project in the UK, who were suspected of having a genetic neurological disorder (familial or early-onset forms of ataxia, neuropathy, spastic paraplegia, dementia, motor neuron disease, parkinsonian movement disorders, intellectual disability, or neuromuscular disorders). If a repeat expansion call was made using whole genome sequencing, PCR was used to confirm the result. FINDINGS The diagnostic accuracy of whole genome sequencing to detect repeat expansions was evaluated against 793 PCR tests previously performed within the NHS from 404 patients. Whole genome sequencing correctly classified 215 of 221 expanded alleles and 1316 of 1321 non-expanded alleles, showing 97·3% sensitivity (95% CI 94·2-99·0) and 99·6% specificity (99·1-99·9) across the 13 disease-associated loci when compared with PCR test results. In samples from 11 631 patients in the 100 000 Genomes Project, whole genome sequencing identified 81 repeat expansions, which were also tested by PCR: 68 were confirmed as repeat expansions in the full pathogenic range, 11 were non-pathogenic intermediate expansions or premutations, and two were non-expanded repeats (16% false discovery rate). INTERPRETATION In our study, whole genome sequencing for the detection of repeat expansions showed high sensitivity and specificity, and it led to identification of neurological repeat expansion disorders in previously undiagnosed patients. These findings support implementation of whole genome sequencing in clinical laboratories for diagnosis of patients who have a neurological presentation consistent with a repeat expansion disorder. FUNDING Medical Research Council, Department of Health and Social Care, National Health Service England, National Institute for Health Research, and Illumina.
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Affiliation(s)
- Kristina Ibañez
- Genomics England, Queen Mary University of London, London, UK; William Harvey Research Institute, Queen Mary University of London, London, UK
| | - James Polke
- Neurogenetics Unit, National Hospital for Neurology and Neurosurgery, London, UK
| | | | | | - Dorota Pasko
- Genomics England, Queen Mary University of London, London, UK
| | | | - Louise C Daugherty
- Genomics England, Queen Mary University of London, London, UK; Healx, Cambridge, UK
| | - Dalia Kasperaviciute
- Genomics England, Queen Mary University of London, London, UK; William Harvey Research Institute, Queen Mary University of London, London, UK
| | - Katherine R Smith
- Genomics England, Queen Mary University of London, London, UK; William Harvey Research Institute, Queen Mary University of London, London, UK
| | | | - Zandra C Deans
- Genomics Quality Assessment, Department of Laboratory Medicine, Royal Infirmary of Edinburgh, Edinburgh, UK; NHS England and NHS Improvement, London, UK
| | - Sue Hill
- NHS England and NHS Improvement, London, UK
| | - Tom Fowler
- Genomics England, Queen Mary University of London, London, UK
| | - Richard H Scott
- Genomics England, Queen Mary University of London, London, UK; Department of Genetics and Genomic Medicine, UCL Great Ormond Street Institute of Child Health, London, UK
| | - John Hardy
- Department of Neurodegenerative Disorders, Institute of Neurology, University College London, London, UK
| | - Patrick F Chinnery
- MRC Mitochondrial Biology Unit and Department of ClinicalNeurosciences, University of Cambridge, Cambridge, UK
| | - Henry Houlden
- Neurogenetics Unit, National Hospital for Neurology and Neurosurgery, London, UK; Department of Neuromuscular Diseases, Institute of Neurology, University College London, London, UK
| | - Augusto Rendon
- Genomics England, Queen Mary University of London, London, UK
| | - Mark J Caulfield
- Genomics England, Queen Mary University of London, London, UK; William Harvey Research Institute, Queen Mary University of London, London, UK
| | | | | | - Arianna Tucci
- Genomics England, Queen Mary University of London, London, UK; William Harvey Research Institute, Queen Mary University of London, London, UK.
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17
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Lockhart PJ. Advancing the diagnosis of repeat expansion disorders. Lancet Neurol 2022; 21:205-207. [DOI: 10.1016/s1474-4422(22)00033-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Accepted: 01/21/2022] [Indexed: 10/19/2022]
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18
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Pagni S, Mills JD, Frankish A, Mudge JM, Sisodiya SM. Non-coding regulatory elements: Potential roles in disease and the case of epilepsy. Neuropathol Appl Neurobiol 2021; 48:e12775. [PMID: 34820881 DOI: 10.1111/nan.12775] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Revised: 10/04/2021] [Accepted: 11/16/2021] [Indexed: 12/27/2022]
Abstract
Non-coding DNA (ncDNA) refers to the portion of the genome that does not code for proteins and accounts for the greatest physical proportion of the human genome. ncDNA includes sequences that are transcribed into RNA molecules, such as ribosomal RNAs (rRNAs), microRNAs (miRNAs), long non-coding RNAs (lncRNAs) and un-transcribed sequences that have regulatory functions, including gene promoters and enhancers. Variation in non-coding regions of the genome have an established role in human disease, with growing evidence from many areas, including several cancers, Parkinson's disease and autism. Here, we review the features and functions of the regulatory elements that are present in the non-coding genome and the role that these regions have in human disease. We then review the existing research in epilepsy and emphasise the potential value of further exploring non-coding regulatory elements in epilepsy. In addition, we outline the most widely used techniques for recognising regulatory elements throughout the genome, current methodologies for investigating variation and the main challenges associated with research in the field of non-coding DNA.
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Affiliation(s)
- Susanna Pagni
- Department of Clinical and Experimental Epilepsy, UCL Queen Square Institute of Neurology, London, UK.,Chalfont Centre for Epilepsy, Chalfont St Peter, UK
| | - James D Mills
- Department of Clinical and Experimental Epilepsy, UCL Queen Square Institute of Neurology, London, UK.,Chalfont Centre for Epilepsy, Chalfont St Peter, UK.,Amsterdam UMC, Department of (Neuro)Pathology, Amsterdam Neuroscience, University of Amsterdam, Amsterdam, Netherlands
| | - Adam Frankish
- European Molecular Biology Laboratory, European Bioinformatics Institute, Cambridge, UK
| | - Jonathan M Mudge
- European Molecular Biology Laboratory, European Bioinformatics Institute, Cambridge, UK
| | - Sanjay M Sisodiya
- Department of Clinical and Experimental Epilepsy, UCL Queen Square Institute of Neurology, London, UK.,Chalfont Centre for Epilepsy, Chalfont St Peter, UK
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19
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Macken WL, Vandrovcova J, Hanna MG, Pitceathly RDS. Applying genomic and transcriptomic advances to mitochondrial medicine. Nat Rev Neurol 2021; 17:215-230. [PMID: 33623159 DOI: 10.1038/s41582-021-00455-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/06/2021] [Indexed: 02/07/2023]
Abstract
Next-generation sequencing (NGS) has increased our understanding of the molecular basis of many primary mitochondrial diseases (PMDs). Despite this progress, many patients with suspected PMD remain without a genetic diagnosis, which restricts their access to in-depth genetic counselling, reproductive options and clinical trials, in addition to hampering efforts to understand the underlying disease mechanisms. Although they represent a considerable improvement over their predecessors, current methods for sequencing the mitochondrial and nuclear genomes have important limitations, and molecular diagnostic techniques are often manual and time consuming. However, recent advances in genomics and transcriptomics offer realistic solutions to these challenges. In this Review, we discuss the current genetic testing approach for PMDs and the opportunities that exist for increased use of whole-genome NGS of nuclear and mitochondrial DNA (mtDNA) in the clinical environment. We consider the possible role for long-read approaches in sequencing of mtDNA and in the identification of novel nuclear genomic causes of PMDs. We examine the expanding applications of RNA sequencing, including the detection of cryptic variants that affect splicing and gene expression and the interpretation of rare and novel mitochondrial transfer RNA variants.
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Affiliation(s)
- William L Macken
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery, London, UK
| | - Jana Vandrovcova
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery, London, UK
| | - Michael G Hanna
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery, London, UK
| | - Robert D S Pitceathly
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery, London, UK.
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20
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I D, Proskokova T, Sikora N, Abramycheva N, Illarioshkin S. Spinocerebellar ataxia 17: full phenotype in a 42 CAG/CAA-repeats carrier. Zh Nevrol Psikhiatr Im S S Korsakova 2021; 121:100-105. [DOI: 10.17116/jnevro2021121121100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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21
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DRPLA: understanding the natural history and developing biomarkers to accelerate therapeutic trials in a globally rare repeat expansion disorder. J Neurol 2020; 268:3031-3041. [PMID: 33106889 PMCID: PMC8289787 DOI: 10.1007/s00415-020-10218-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Revised: 09/02/2020] [Accepted: 09/03/2020] [Indexed: 02/07/2023]
Abstract
Dentatorubral–pallidoluysian atrophy (DRPLA) is a rare neurodegenerative disorder caused by CAG repeat expansions in the atrophin-1 gene and is inherited in an autosomal dominant fashion. There are currently no disease-modifying treatments available. The broad development of therapies for DRPLA, as well as other similar rare diseases, has hit a roadblock due to the rarity of the condition and the wide global distribution of patients and families, consequently inhibiting biomarker development and therapeutic research. Considering the shifting focus towards diverse populations, widespread genetic testing, rapid advancements in the development of clinical and wet biomarkers for Huntington’s disease (HD), and the ongoing clinical trials for antisense oligonucleotide (ASO) therapies, the prospect of developing effective treatments in rare disorders has completely changed. The awareness of the HD ASO program has prompted global collaboration for rare disorders in natural history studies and the development of biomarkers, with the eventual goal of undergoing treatment trials. Here, we discuss DRPLA, which shares similarities with HD, and how in this and other repeat expansion disorders, neurogenetics groups like ours at UCL are gearing up for forthcoming natural history studies to accelerate future ASO treatment trials to hopefully emulate the progress seen in HD.
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