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Jaklič H, Božović IB, Peterlin B, Kovanda A. Streamlined two-step fragment analysis PCR and exome sequencing of RFC1 for diagnostic testing of suspected CANVAS patients. Clin Genet 2024; 106:632-637. [PMID: 38984515 DOI: 10.1111/cge.14586] [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: 03/25/2024] [Revised: 05/08/2024] [Accepted: 06/27/2024] [Indexed: 07/11/2024]
Abstract
Cerebellar ataxia, neuropathy, and vestibular areflexia syndrome (CANVAS) is caused by biallelic pathogenic expansions, or compound heterozygosity with other pathogenic variants in the RFC1 gene. CANVAS is estimated to be underdiagnosed, both because of the lack of formal diagnostic criteria and molecular challenges that translate to lesser access and high cost of routine testing. Our aim was to address the need for making CANVAS genetic testing routine, by designing a streamlined two-step PCR consisting of a short-allele screening PCR and a confirmatory PCR with fragment capillary electrophoresis detection. Exome sequencing of RFC1 was additionally foreseen to resolve potential compound heterozygosity cases. Specificity of our approach was evaluated using ataxia patients with known non-CANVAS diagnoses, and optimized using Southern blot confirmed CANVAS patients. We evaluated our approach by testing patients consecutively referred for clinically suspected CANVAS using first the two-step PCR, followed by exome sequencing. Our approach was able to accurately identify negative and confirm positive cases in prospectively collected suspected CANVAS patients presenting with at least three typical clinical signs. The proposed testing approach provides an alternative method able to clearly distinguish between CANVAS negative and positive cases and can be easily incorporated into the genetic diagnostic laboratory workflow.
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Affiliation(s)
- Helena Jaklič
- Clinical Institute of Genomic Medicine, University Medical Center Ljubljana, Ljubljana, Slovenia
- Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Ivana Babič Božović
- Clinical Institute of Genomic Medicine, University Medical Center Ljubljana, Ljubljana, Slovenia
- Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Borut Peterlin
- Clinical Institute of Genomic Medicine, University Medical Center Ljubljana, Ljubljana, Slovenia
- Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Anja Kovanda
- Clinical Institute of Genomic Medicine, University Medical Center Ljubljana, Ljubljana, Slovenia
- Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
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2
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Schaub A, Erdmann H, Scholz V, Timmer M, Cordts I, Günther R, Reilich P, Abicht A, Schöberl F. Analysis and occurrence of biallelic pathogenic repeat expansions in RFC1 in a German cohort of patients with a main clinical phenotype of motor neuron disease. J Neurol 2024; 271:5804-5812. [PMID: 38916676 PMCID: PMC11377604 DOI: 10.1007/s00415-024-12519-6] [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: 05/01/2024] [Revised: 06/09/2024] [Accepted: 06/11/2024] [Indexed: 06/26/2024]
Abstract
Biallelic pathogenic repeat expansions in RFC1 were recently identified as molecular origin of cerebellar ataxia, neuropathy, vestibular areflexia syndrome (CANVAS) as well as of one of the most common causes of adult-onset ataxia. In the meantime, the phenotypic spectrum has expanded massively and now includes mimics of multiple system atrophy or parkinsonism. After identifying a patient with a clinical diagnosis of amyotrophic lateral sclerosis (ALS) as a carrier of biallelic pathogenic repeat expansions in RFC1, we studied a cohort of 106 additional patients with a clinical main phenotype of motor neuron disease (MND) to analyze whether such repeat expansions are more common in MND patients. Indeed, two additional MND patients (one also with ALS and one with primary lateral sclerosis/PLS) have been identified as carrier of biallelic pathogenic repeat expansions in RFC1 in the absence of another genetic alteration explaining the phenotype, suggesting motor neuron disease as another extreme phenotype of RFC1 spectrum disorder. Therefore, MND might belong to the expanding phenotypic spectrum of pathogenic RFC1 repeat expansions, particularly in those MND patients with additional features such as sensory and/or autonomic neuropathy, vestibular deficits, or cerebellar signs. By systematically analyzing the RFC1 repeat array using Oxford nanopore technology long-read sequencing, our study highlights the high intra- and interallelic heterogeneity of this locus and allows the identification of the novel repeat motif 'ACAAG'.
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Affiliation(s)
- Annalisa Schaub
- Medical Genetics Center, Munich, Germany
- Department of Neurology With Friedrich-Baur-Institute, Klinikum Der Universität, Ludwig-Maximilians-University, Marchioninistr. 15, 81377, Munich, Germany
| | - Hannes Erdmann
- Medical Genetics Center, Munich, Germany
- Department of Neurology With Friedrich-Baur-Institute, Klinikum Der Universität, Ludwig-Maximilians-University, Marchioninistr. 15, 81377, Munich, Germany
| | | | - Manuela Timmer
- Gemeinschaftspraxis Für Humangenetik Dresden, Medizinische Genetik, Dresden, Germany
| | - Isabell Cordts
- Department of Neurology, Klinikum Rechts Der Isar, Technical University of Munich, Munich, Germany
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL, USA
| | - Rene Günther
- Department of Neurology, Universitätsklinikum Carl Gustav Carus Dresden, Dresden, Germany
| | - Peter Reilich
- Department of Neurology With Friedrich-Baur-Institute, Klinikum Der Universität, Ludwig-Maximilians-University, Marchioninistr. 15, 81377, Munich, Germany
| | - Angela Abicht
- Medical Genetics Center, Munich, Germany
- Department of Neurology With Friedrich-Baur-Institute, Klinikum Der Universität, Ludwig-Maximilians-University, Marchioninistr. 15, 81377, Munich, Germany
| | - Florian Schöberl
- Department of Neurology With Friedrich-Baur-Institute, Klinikum Der Universität, Ludwig-Maximilians-University, Marchioninistr. 15, 81377, Munich, Germany.
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3
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Horowitz T, Guedj E, Eusebio A, Fluchère F, Azulay JP, Delmont E, Grimaldi S. Molecular Imaging in CANVAS: A Contribution for Differential Diagnosis? Mov Disord Clin Pract 2024; 11:879-885. [PMID: 38576115 PMCID: PMC11233850 DOI: 10.1002/mdc3.14041] [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: 11/21/2023] [Revised: 02/02/2024] [Accepted: 03/17/2024] [Indexed: 04/06/2024] Open
Abstract
BACKGROUND Phenotypes of CANVAS are increasingly diversified, including bradykinesia and dysautonomia, so that its primary differential diagnoses are multiple system atrophy-cerebellar type (MSA-c), and spinocerebellar ataxia type 3 (SCA3). This case series aims to highlight key molecular imaging findings in CANVAS. CASES We report a case series of six patients with CANVAS who underwent nuclear medicine examinations in our center and 13 patients from the literature. These include 18F-FDG brain positron emission tomography (PET), single photon emission computed tomography (SPECT) of dopamine transporter (DaT) activity, and 123I-MIBG cardiac scintigraphy of noradrenergic transmission. CONCLUSIONS In CANVAS, 18F-FDG brain PET mainly shows cerebellar hypometabolism, with preserved brainstem and striatum metabolism, contrasting with SCA3 and MSA-c. Dopaminergic denervation on scintigraphy seems to be associated with clinical parkinsonism, ranging from normal to severely impaired DaT SPECT. Additionally, 123I-MIBG cardiac scintigraphy might show denervation in CANVAS, similar to SCA3, but not in most MSA-c patients.
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Affiliation(s)
- Tatiana Horowitz
- Nuclear Medicine Department, Aix Marseille Univ, APHM, CNRS, Centrale Marseille, Institut Fresnel, Timone Hospital, CERIMED, Marseille, France
| | - Eric Guedj
- Nuclear Medicine Department, Aix Marseille Univ, APHM, CNRS, Centrale Marseille, Institut Fresnel, Timone Hospital, CERIMED, Marseille, France
| | - Alexandre Eusebio
- Neurology and Movement Disorders Department, APHM, Timone University Hospital, Marseille, France
| | - Frédérique Fluchère
- Neurology and Movement Disorders Department, APHM, Timone University Hospital, Marseille, France
| | - Jean-Philippe Azulay
- Neurology and Movement Disorders Department, APHM, Timone University Hospital, Marseille, France
| | - Emilien Delmont
- Neurology Department, Reference Center for Neuromuscular Diseases and ALS, Public Assistance Hospitals of Marseille, Timone University Hospital, Marseille, France
| | - Stephan Grimaldi
- Neurology and Movement Disorders Department, APHM, Timone University Hospital, Marseille, France
- CRMBM, CEMEREM, CNRS, Aix Marseille Univ, Marseille, France
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4
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Alvarez Jerez P, Daida K, Miano-Burkhardt A, Iwaki H, Malik L, Cogan G, Makarious MB, Sullivan R, Vandrovcova J, Ding J, Gibbs JR, Markham A, Nalls MA, Kesharwani RK, Sedlazeck FJ, Casey B, Hardy J, Houlden H, Blauwendraat C, Singleton AB, Billingsley KJ. Profiling complex repeat expansions in RFC1 in Parkinson's disease. NPJ Parkinsons Dis 2024; 10:108. [PMID: 38789445 PMCID: PMC11126591 DOI: 10.1038/s41531-024-00723-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Accepted: 05/10/2024] [Indexed: 05/26/2024] Open
Abstract
A biallelic (AAGGG) expansion in the poly(A) tail of an AluSx3 transposable element within the gene RFC1 is a frequent cause of cerebellar ataxia, neuropathy, vestibular areflexia syndrome (CANVAS), and more recently, has been reported as a rare cause of Parkinson's disease (PD) in the Finnish population. Here, we investigate the prevalence of RFC1 (AAGGG) expansions in PD patients of non-Finnish European ancestry in 1609 individuals from the Parkinson's Progression Markers Initiative study. We identified four PD patients carrying the biallelic RFC1 (AAGGG) expansion and did not identify any carriers in controls.
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Affiliation(s)
- Pilar Alvarez Jerez
- Laboratory of Neurogenetics, National Institute on Aging, Bethesda, MD, USA
- Center for Alzheimer's and Related Dementias, National Institute on Aging, Bethesda, MD, USA
- Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, University College London, London, UK
| | - Kensuke Daida
- Laboratory of Neurogenetics, National Institute on Aging, Bethesda, MD, USA
- Center for Alzheimer's and Related Dementias, National Institute on Aging, Bethesda, MD, USA
| | - Abigail Miano-Burkhardt
- Laboratory of Neurogenetics, National Institute on Aging, Bethesda, MD, USA
- Center for Alzheimer's and Related Dementias, National Institute on Aging, Bethesda, MD, USA
| | - Hirotaka Iwaki
- Laboratory of Neurogenetics, National Institute on Aging, Bethesda, MD, USA
- Center for Alzheimer's and Related Dementias, National Institute on Aging, Bethesda, MD, USA
- DataTecnica LLC, Washington, DC, USA
| | - Laksh Malik
- Center for Alzheimer's and Related Dementias, National Institute on Aging, Bethesda, MD, USA
| | - Guillaume Cogan
- Laboratory of Neurogenetics, National Institute on Aging, Bethesda, MD, USA
- Sorbonne Université, Institut du Cerveau-Paris Brain Institute-ICM, Institut National de la Recherche Médicale-U1127, Centre National de la Recherche Scientifique, Paris, France
| | - Mary B Makarious
- Laboratory of Neurogenetics, National Institute on Aging, Bethesda, MD, USA
- UCL Movement Disorders Centre, University College London, London, UK
| | - Roisin Sullivan
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, UK
| | - Jana Vandrovcova
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, UK
| | - Jinhui Ding
- Laboratory of Neurogenetics, National Institute on Aging, Bethesda, MD, USA
| | - J Raphael Gibbs
- Laboratory of Neurogenetics, National Institute on Aging, Bethesda, MD, USA
| | | | - Mike A Nalls
- Laboratory of Neurogenetics, National Institute on Aging, Bethesda, MD, USA
- Center for Alzheimer's and Related Dementias, National Institute on Aging, Bethesda, MD, USA
- DataTecnica LLC, Washington, DC, USA
| | - Rupesh K Kesharwani
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX, USA
| | - Fritz J Sedlazeck
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Department of Computer Science, Rice University, Houston, TX, USA
| | - Bradford Casey
- The Michael J. Fox Foundation for Parkinson's Research, New York, NY, USA
| | - John Hardy
- Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, University College London, London, UK
| | - Henry Houlden
- UCL Movement Disorders Centre, University College London, London, UK
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, UK
| | - Cornelis Blauwendraat
- Laboratory of Neurogenetics, National Institute on Aging, Bethesda, MD, USA
- Center for Alzheimer's and Related Dementias, National Institute on Aging, Bethesda, MD, USA
| | - Andrew B Singleton
- Laboratory of Neurogenetics, National Institute on Aging, Bethesda, MD, USA
- Center for Alzheimer's and Related Dementias, National Institute on Aging, Bethesda, MD, USA
| | - Kimberley J Billingsley
- Laboratory of Neurogenetics, National Institute on Aging, Bethesda, MD, USA.
- Center for Alzheimer's and Related Dementias, National Institute on Aging, Bethesda, MD, USA.
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5
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Delforge V, Tard C, Davion JB, Dujardin K, Wissocq A, Dhaenens CM, Mutez E, Huin V. RFC1: Motifs and phenotypes. Rev Neurol (Paris) 2024; 180:393-409. [PMID: 38627134 DOI: 10.1016/j.neurol.2024.03.006] [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: 01/30/2024] [Revised: 03/22/2024] [Accepted: 03/25/2024] [Indexed: 05/28/2024]
Abstract
Biallelic intronic expansions (AAGGG)exp in intron 2 of the RFC1 gene have been shown to be a common cause of late-onset ataxia. Since their first description, the phenotypes, neurological damage, and pathogenic variants associated with the RFC1 gene have been frequently updated. Here, we review the various motifs, genetic variants, and phenotypes associated with the RFC1 gene. We searched PubMed for scientific articles published between March 1st, 2019, and January 15th, 2024. The motifs and phenotypes associated with the RFC1 gene are highly heterogeneous, making molecular diagnosis and clinical screening and investigation challenging. In this review we will provide clues to give a better understanding of RFC1 disease. We briefly discuss new methods for molecular diagnosis, the origin of cough in RFC1 disease, and research perspectives.
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Affiliation(s)
- V Delforge
- Inserm, U1172 - LilNCog - Lille Neuroscience & Cognition, CHU de Lille, University Lille, 59000 Lille, France
| | - C Tard
- Inserm, U1172 - LilNCog - Lille Neuroscience & Cognition, CHU de Lille, University Lille, 59000 Lille, France; Department of Neurology and Movement disorders, CHU de Lille, 59000 Lille, France
| | - J-B Davion
- Inserm, U1172 - LilNCog - Lille Neuroscience & Cognition, CHU de Lille, University Lille, 59000 Lille, France; Department of Neurology and Movement disorders, CHU de Lille, 59000 Lille, France
| | - K Dujardin
- Inserm, U1172 - LilNCog - Lille Neuroscience & Cognition, CHU de Lille, University Lille, 59000 Lille, France; Department of Neurology and Movement disorders, CHU de Lille, 59000 Lille, France
| | - A Wissocq
- Department of Toxicology and Genopathies, UF Neurobiology, CHU de Lille, 59000 Lille, France
| | - C-M Dhaenens
- Inserm, U1172 - LilNCog - Lille Neuroscience & Cognition, CHU de Lille, University Lille, 59000 Lille, France; Department of Toxicology and Genopathies, UF Neurobiology, CHU de Lille, 59000 Lille, France
| | - E Mutez
- Inserm, U1172 - LilNCog - Lille Neuroscience & Cognition, CHU de Lille, University Lille, 59000 Lille, France; Department of Neurology and Movement disorders, CHU de Lille, 59000 Lille, France
| | - V Huin
- Inserm, U1172 - LilNCog - Lille Neuroscience & Cognition, CHU de Lille, University Lille, 59000 Lille, France; Department of Toxicology and Genopathies, UF Neurobiology, CHU de Lille, 59000 Lille, France.
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6
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Wang Y, Wang J, Yan Z, Hou J, Wan L, Yang Y, Liu Y, Yi J, Guo P, Han D. Structural investigation of pathogenic RFC1 AAGGG pentanucleotide repeats reveals a role of G-quadruplex in dysregulated gene expression in CANVAS. Nucleic Acids Res 2024; 52:2698-2710. [PMID: 38266156 PMCID: PMC10954463 DOI: 10.1093/nar/gkae032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2023] [Revised: 01/04/2024] [Accepted: 01/08/2024] [Indexed: 01/26/2024] Open
Abstract
An expansion of AAGGG pentanucleotide repeats in the replication factor C subunit 1 (RFC1) gene is the genetic cause of cerebellar ataxia, neuropathy, and vestibular areflexia syndrome (CANVAS), and it also links to several other neurodegenerative diseases including the Parkinson's disease. However, the pathogenic mechanism of RFC1 AAGGG repeat expansion remains enigmatic. Here, we report that the pathogenic RFC1 AAGGG repeats form DNA and RNA parallel G-quadruplex (G4) structures that play a role in impairing biological processes. We determine the first high-resolution nuclear magnetic resonance (NMR) structure of a bimolecular parallel G4 formed by d(AAGGG)2AA and reveal how AAGGG repeats fold into a higher-order structure composed of three G-tetrad layers, and further demonstrate the formation of intramolecular G4s in longer DNA and RNA repeats. The pathogenic AAGGG repeats, but not the nonpathogenic AAAAG repeats, form G4 structures to stall DNA replication and reduce gene expression via impairing the translation process in a repeat-length-dependent manner. Our results provide an unprecedented structural basis for understanding the pathogenic mechanism of AAGGG repeat expansion associated with CANVAS. In addition, the high-resolution structures resolved in this study will facilitate rational design of small-molecule ligands and helicases targeting G4s formed by AAGGG repeats for therapeutic interventions.
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Affiliation(s)
- Yang Wang
- School of Materials Science and Engineering, Tianjin University, Tianjin 300350, China
- Zhejiang Cancer Hospital, Hangzhou Institute of Medicine (HIM), Chinese Academy of Sciences, Hangzhou, Zhejiang 310022, China
| | - Junyan Wang
- Zhejiang Cancer Hospital, Hangzhou Institute of Medicine (HIM), Chinese Academy of Sciences, Hangzhou, Zhejiang 310022, China
| | - Zhenzhen Yan
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou, Guangdong 510006, China
| | - Jianing Hou
- Institute of Molecular Medicine (IMM) Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China
| | - Liqi Wan
- Zhejiang Cancer Hospital, Hangzhou Institute of Medicine (HIM), Chinese Academy of Sciences, Hangzhou, Zhejiang 310022, China
| | - Yingquan Yang
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou, Guangdong 510006, China
| | - Yu Liu
- Zhejiang Cancer Hospital, Hangzhou Institute of Medicine (HIM), Chinese Academy of Sciences, Hangzhou, Zhejiang 310022, China
| | - Jie Yi
- Zhejiang Cancer Hospital, Hangzhou Institute of Medicine (HIM), Chinese Academy of Sciences, Hangzhou, Zhejiang 310022, China
| | - Pei Guo
- Zhejiang Cancer Hospital, Hangzhou Institute of Medicine (HIM), Chinese Academy of Sciences, Hangzhou, Zhejiang 310022, China
| | - Da Han
- Zhejiang Cancer Hospital, Hangzhou Institute of Medicine (HIM), Chinese Academy of Sciences, Hangzhou, Zhejiang 310022, China
- Institute of Molecular Medicine (IMM) Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China
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7
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Tyagi N, Uppili B, Sharma P, Parveen S, Saifi S, Jain A, Sonakar A, Ahmed I, Sahni S, Shamim U, Anand A, Suroliya V, Asokachandran V, Srivastava A, Sivasubbu S, Scaria V, Faruq M. Investigation of RFC1 tandem nucleotide repeat locus in diverse neurodegenerative outcomes in an Indian cohort. Neurogenetics 2024; 25:13-25. [PMID: 37917284 DOI: 10.1007/s10048-023-00736-6] [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: 06/02/2023] [Accepted: 10/10/2023] [Indexed: 11/04/2023]
Abstract
An intronic bi-allelic pentanucleotide repeat expansion mutation, (AAGGG)400-2000, at AAAAG repeat locus in RFC1 gene, is known as underlying genetic cause in cases with cerebellar ataxia, neuropathy, and vestibular areflexia syndrome (CANVAS) and late-onset sporadic ataxia. Biallelic positive cases carry a common recessive risk haplotype, "AAGA," spanning RFC1 gene. In this study, our aim is to find prevalence of bi-allelic (AAGGG)exp in Indian ataxia and other neurological disorders and investigate the complexity of RFC1 repeat locus and its potential association with neurodegenerative diseases in Indian population-based cohorts. We carried out repeat number and repeat type estimation using flanking PCR and repeat primed PCR (AAAAG/AAAGG/AAGGG) in four Indian disease cohorts and healthy controls. Haplotype assessment of suspected cases was done by genotyping and confirmed by Sanger sequencing. Blood samples and consent of all the cases and detailed clinical details of positive cases were collected in collaboration with A.I.I.M.S. Furthermore, comprehension of RFC1 repeat locus and risk haplotype analysis in Indian background was performed on the NGS data of Indian healthy controls by ExpansionHunter, ExpansionHunter Denovo, and PHASE analysis, respectively. Genetic screening of RFC1-TNR locus in 1998 uncharacterized cases (SCA12: 87; uncharacterized ataxia: 1818, CMT: 93) and 564 heterogenous controls showed that the frequency of subjects with bi-allelic (AAGGG)exp are 1.15%, < 0.05%, 2.15%, and 0% respectively. Two RFC1 positive sporadic late-onset ataxia cases, one bi-allelic (AAGGG)exp and another, (AAAGG)~700/(AAGGG)exp, had recessive risk haplotype and CANVAS symptoms. Long normal alleles, 15-27, are significantly rare in ataxia cohort. In IndiGen control population (IndiGen; N = 1029), long normal repeat range, 15-27, is significantly associated with A3G3 and some rare repeat motifs, AGAGG, AACGG, AAGAG, and AAGGC. Risk-associated "AAGA" haplotype of the original pathogenic expansion of A2G3 was found associated with the A3G3 representing alleles in background population. Apart from bi-allelic (AAGGG)exp, we report cases with a new pathogenic expansion of (AAAGG)exp/(AAGGG)exp in RFC1 and recessive risk haplotype. We found different repeat motifs at RFC1 TNR locus, like AAAAG, AAAGG, AAAGGG, AAAAGG, AAGAG, AACGG, AAGGC, AGAGG, and AAGGG, in Indian background population except ACAGG and (AAAGG)n/(AAGGG)n. Our findings will help in further understanding the role of long normal repeat size and different repeat motifs, specifically AAAGG, AAAGGG, and other rare repeat motifs, at the RFC1 locus.
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Affiliation(s)
- Nishu Tyagi
- Genomics and Molecular Medicine Division, CSIR - Institute of Genomics and Integrative Biology, New Delhi, 110007, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
| | - Bharathram Uppili
- Genomics and Molecular Medicine Division, CSIR - Institute of Genomics and Integrative Biology, New Delhi, 110007, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
| | - Pooja Sharma
- Genomics and Molecular Medicine Division, CSIR - Institute of Genomics and Integrative Biology, New Delhi, 110007, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
| | - Shaista Parveen
- Genomics and Molecular Medicine Division, CSIR - Institute of Genomics and Integrative Biology, New Delhi, 110007, India
| | - Sheeba Saifi
- Genomics and Molecular Medicine Division, CSIR - Institute of Genomics and Integrative Biology, New Delhi, 110007, India
| | - Abhinav Jain
- Genomics and Molecular Medicine Division, CSIR - Institute of Genomics and Integrative Biology, New Delhi, 110007, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
| | - Akhilesh Sonakar
- Department of Neurology, Neuroscience Centre, All India Institute of Medical Sciences (AIIMS), 110608, New Delhi, India
| | - Istaq Ahmed
- Genomics and Molecular Medicine Division, CSIR - Institute of Genomics and Integrative Biology, New Delhi, 110007, India
| | - Shweta Sahni
- Department of Neurology, Neuroscience Centre, All India Institute of Medical Sciences (AIIMS), 110608, New Delhi, India
| | - Uzma Shamim
- Genomics and Molecular Medicine Division, CSIR - Institute of Genomics and Integrative Biology, New Delhi, 110007, India
| | - Avni Anand
- Genomics and Molecular Medicine Division, CSIR - Institute of Genomics and Integrative Biology, New Delhi, 110007, India
| | - Varun Suroliya
- Department of Neurology, Neuroscience Centre, All India Institute of Medical Sciences (AIIMS), 110608, New Delhi, India
| | - Vivekanand Asokachandran
- Genomics and Molecular Medicine Division, CSIR - Institute of Genomics and Integrative Biology, New Delhi, 110007, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
| | - Achal Srivastava
- Department of Neurology, Neuroscience Centre, All India Institute of Medical Sciences (AIIMS), 110608, New Delhi, India
| | - Sridhar Sivasubbu
- Genomics and Molecular Medicine Division, CSIR - Institute of Genomics and Integrative Biology, New Delhi, 110007, India
| | - Vinod Scaria
- Genomics and Molecular Medicine Division, CSIR - Institute of Genomics and Integrative Biology, New Delhi, 110007, India
| | - Mohammed Faruq
- Genomics and Molecular Medicine Division, CSIR - Institute of Genomics and Integrative Biology, New Delhi, 110007, India.
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India.
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8
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Azevedo MPC, Lobo CC, Schmitt GS, Matos PCAAP, Barsottini OGP, Pedroso JL, Marques W, Souza JP, Amorim BJ, França MC. Nigrostriatal dysfunction in RFC1-related disorder/CANVAS. Parkinsonism Relat Disord 2023; 115:105854. [PMID: 37729670 DOI: 10.1016/j.parkreldis.2023.105854] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Revised: 09/08/2023] [Accepted: 09/11/2023] [Indexed: 09/22/2023]
Abstract
INTRODUCTION Parkinsonism is now recognized as an additional feature in RFC1/CANVAS syndrome; however, no systematic evaluation of nigrostriatal dopaminergic function has been published so far. METHODS This is an observational, single-center study, which analyzed 13 patients with molecular confirmation of RFC1/CANVAS. Disease severity was assessed with the SARA scale. Each subject was carefully evaluated for the presence of parkinsonian features. Dopamine transporter (DAT) imaging was acquired and reconstructed in the transverse, coronal and sagittal planes 4 h after venous injection of 99mTc-TRODAT-1. An experienced nuclear physician performed the visual analysis of all images. RESULTS Patients had a mean age of 62.3 ± 8.8 years, and there were 9 women. The mean SARA score was 15.5 ± 5.8. Nine patients had abnormal DAT imaging results. The putamen was more frequently affected than the caudate nucleus on both sides. Considering all regions, uptake of 99mTc-TRODAT-1 did not correlate with disease duration or SARA scores. Parkinsonism was noticed in 3/13 patients, all of which had abnormal DAT scans. Interestingly, six subjects had reduced DAT imaging uptake, but no clinical signs of parkinsonism. CONCLUSION Nigrostriatal dysfunction is frequent in RFC1/CANVAS even in the absence of clinical parkinsonism and may occur early in the disease course.
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Affiliation(s)
- Maria Paula C Azevedo
- Department of Neurology, School of Medical Sciences - University of Campinas (UNICAMP), Campinas, SP, Brazil
| | - Camila C Lobo
- Department of Neurology, School of Medical Sciences - University of Campinas (UNICAMP), Campinas, SP, Brazil
| | - Gabriel S Schmitt
- Department of Neurology, School of Medical Sciences - University of Campinas (UNICAMP), Campinas, SP, Brazil
| | - Paula C A A P Matos
- Department of Neurology and Neurosurgery, School of Medicine - Federal University of São Paulo (UNIFESP), São Paulo SP, Brazil
| | - Orlando G P Barsottini
- Department of Neurology and Neurosurgery, School of Medicine - Federal University of São Paulo (UNIFESP), São Paulo SP, Brazil
| | - José Luiz Pedroso
- Department of Neurology and Neurosurgery, School of Medicine - Federal University of São Paulo (UNIFESP), São Paulo SP, Brazil
| | - Wilson Marques
- Department of Neurosciences, School of Medicine - University of São Paulo at Ribeirão Preto (USP-RP), Ribeirão Preto, SP, Brazil
| | - Juliana Pasquotto Souza
- Division of Nuclear Medicine, Department of Anesthesiology, Oncology and Radiology (DAOR)School of Medical Sciences - University of Campinas (UNICAMP), Campinas, SP, Brazil
| | - Bárbara J Amorim
- Division of Nuclear Medicine, Department of Anesthesiology, Oncology and Radiology (DAOR)School of Medical Sciences - University of Campinas (UNICAMP), Campinas, SP, Brazil
| | - Marcondes C França
- Department of Neurology, School of Medical Sciences - University of Campinas (UNICAMP), Campinas, SP, Brazil.
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9
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Sipilä JOT. Adult-Onset Neuroepidemiology in Finland: Lessons to Learn and Work to Do. J Clin Med 2023; 12:3972. [PMID: 37373667 PMCID: PMC10298930 DOI: 10.3390/jcm12123972] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2023] [Revised: 06/07/2023] [Accepted: 06/09/2023] [Indexed: 06/29/2023] Open
Abstract
Finland is a relatively small genetic isolate with a genetically non-homogenous population. Available Finnish data on neuroepidemiology of adult-onset disorders are limited, and this paper describes the conclusions that can be drawn and their implications. Apparently, Finnish people have a (relatively) high risk of developing Unverricht-Lundborg disease (EPM1), Multiple Sclerosis (MS), Amyotrophic Lateral Sclerosis (ALS), Spinal muscular atrophy, Jokela type (SMAJ) and adult-onset dystonia. On the other hand, some disorders, such as Friedreich's ataxia (FRDA) and Wilson's disease (WD), are almost absent or completely absent in the population. Valid and timely data concerning even many common disorders, such as stroke, migraine, neuropathy, Alzheimer's disease and Parkinson's disease, are unavailable, and there are virtually no data on many less-common neurological disorders, such as neurosarcoidosis or autoimmune encephalitides. There also appear to be marked regional differences in the incidence and prevalence of many diseases, suggesting that non-granular nationwide data may be misleading in many cases. Concentrated efforts to advance neuroepidemiological research in the country would be of clinical, administrative and scientific benefit, but currently, all progress is blocked by administrative and financial obstacles.
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Affiliation(s)
- Jussi O. T. Sipilä
- Department of Neurology, North Karelia Central Hospital, Siun Sote, 80210 Joensuu, Finland;
- Clinical Neurosciences, Faculty of Medicine, University of Turku, 20014 Turku, Finland
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10
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Wang H, Wang LS, Schellenberg G, Lee WP. The role of structural variations in Alzheimer's disease and other neurodegenerative diseases. Front Aging Neurosci 2023; 14:1073905. [PMID: 36846102 PMCID: PMC9944073 DOI: 10.3389/fnagi.2022.1073905] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Accepted: 12/31/2022] [Indexed: 02/10/2023] Open
Abstract
Dozens of single nucleotide polymorphisms (SNPs) related to Alzheimer's disease (AD) have been discovered by large scale genome-wide association studies (GWASs). However, only a small portion of the genetic component of AD can be explained by SNPs observed from GWAS. Structural variation (SV) can be a major contributor to the missing heritability of AD; while SV in AD remains largely unexplored as the accurate detection of SVs from the widely used array-based and short-read technology are still far from perfect. Here, we briefly summarized the strengths and weaknesses of available SV detection methods. We reviewed the current landscape of SV analysis in AD and SVs that have been found associated with AD. Particularly, the importance of currently less explored SVs, including insertions, inversions, short tandem repeats, and transposable elements in neurodegenerative diseases were highlighted.
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Affiliation(s)
- Hui Wang
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
- Penn Neurodegeneration Genomics Center, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Li-San Wang
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
- Penn Neurodegeneration Genomics Center, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Gerard Schellenberg
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
- Penn Neurodegeneration Genomics Center, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Wan-Ping Lee
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
- Penn Neurodegeneration Genomics Center, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
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11
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Ylikotila P, Sipilä J, Alapirtti T, Ahmasalo R, Koshimizu E, Miyatake S, Hurme-Niiranen A, Siitonen A, Doi H, Tanaka F, Matsumoto N, Majamaa K, Kytövuori L. Association of biallelic RFC1 expansion with early-onset Parkinson's disease. Eur J Neurol 2023; 30:1256-1261. [PMID: 36705320 DOI: 10.1111/ene.15717] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 01/19/2023] [Accepted: 01/23/2023] [Indexed: 01/28/2023]
Abstract
BACKGROUND AND PURPOSE The biallelic repeat expansion (AAGGG)exp in the replication factor C subunit 1 gene (RFC1) is a frequent cause of cerebellar ataxia, neuropathy and vestibular areflexia syndrome (CANVAS) as well as late-onset ataxia. The clinical spectrum of RFC1 disease has expanded since the first identification of biallelic (AAGGG)exp and includes now various nonclassical phenotypes. Biallelic (AAGGG)exp in RFC1 in patients with clinically confirmed Parkinson's disease (PD) has recently been found. METHODS A nationwide cohort of 273 Finnish patients with early-onset PD was examined for the biallelic intronic expansion in RFC1. The expansion (AAGGG)exp was first screened using extra long polymerase chain reactions (Extra Large-PCRs) and flanking multiplex PCR. The presence of biallelic (AAGGG)exp was then confirmed by repeat-primed PCR and, finally, the repeat length was determined by long-read sequencing. RESULTS Three patients were found with the biallelic (AAGGG)exp in RFC1 giving a frequency of 1.10% (0.23%-3.18%; 95% confidence interval). The three patients fulfilled the diagnostic criteria of PD, none of them had ataxia or neuropathy, and only one patient had a mild vestibular dysfunction. The age at onset of PD symptoms was 40-48 years and their disease course had been unremarkable apart from the early onset. CONCLUSIONS Our results suggest that (AAGGG)exp in RFC1 is a rare cause of early-onset PD. Other populations should be examined in order to determine whether our findings are specific to the Finnish population.
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Affiliation(s)
- Pauli Ylikotila
- Clinical Neurosciences, University of Turku, Turku, Finland.,Neurocenter Turku University Hospital, Turku, Finland
| | - Jussi Sipilä
- Clinical Neurosciences, University of Turku, Turku, Finland.,Department of Neurology, Siun Sote North Karelia Central Hospital, Joensuu, Finland
| | - Tiina Alapirtti
- Department of Neurology, Kanta-Häme Central Hospital, Hämeenlinna, Finland
| | - Riitta Ahmasalo
- Department of Neurology, Lapland Central Hospital, Rovaniemi, Finland
| | - Eriko Koshimizu
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Satoko Miyatake
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Japan.,Department of Clinical Genetics, Yokohama City University Hospital, Yokohama, Japan
| | - Anri Hurme-Niiranen
- Research Unit of Clinical Medicine, Medical Research Center Oulu, Oulu University Hospital, University of Oulu, Oulu, Finland.,Neurocenter, Neurology, Oulu University Hospital, Oulu, Finland
| | - Ari Siitonen
- Research Unit of Clinical Medicine, Medical Research Center Oulu, Oulu University Hospital, University of Oulu, Oulu, Finland.,Neurocenter, Neurology, Oulu University Hospital, Oulu, Finland
| | - Hiroshi Doi
- Department of Neurology and Stroke Medicine, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Fumiaki Tanaka
- Department of Neurology and Stroke Medicine, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Naomichi Matsumoto
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Kari Majamaa
- Research Unit of Clinical Medicine, Medical Research Center Oulu, Oulu University Hospital, University of Oulu, Oulu, Finland.,Neurocenter, Neurology, Oulu University Hospital, Oulu, Finland
| | - Laura Kytövuori
- Research Unit of Clinical Medicine, Medical Research Center Oulu, Oulu University Hospital, University of Oulu, Oulu, Finland.,Neurocenter, Neurology, Oulu University Hospital, Oulu, Finland
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12
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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: 20] [Impact Index Per Article: 10.0] [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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13
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Movement disorders and neuropathies: overlaps and mimics in clinical practice. J Neurol 2022; 269:4646-4662. [PMID: 35657406 DOI: 10.1007/s00415-022-11200-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Accepted: 05/16/2022] [Indexed: 10/18/2022]
Abstract
Movement disorders as well as peripheral neuropathies are extremely frequent in the general population; therefore, it is not uncommon to encounter patients with both these conditions. Often, the coexistence is coincidental, due to the high incidence of common causes of peripheral neuropathy, such as diabetes and other age-related disorders, as well as of Parkinson disease (PD), which has a typical late onset. Nonetheless, there is broad evidence that PD patients may commonly develop a sensory and/or autonomic polyneuropathy, triggered by intrinsic and/or extrinsic mechanisms. Similarly, some peripheral neuropathies may develop some movement disorders in the long run, such as tremor, and rarely dystonia and myoclonus, suggesting that central mechanisms may ensue in the pathogenesis of these diseases. Although rare, several acquired or hereditary causes may be responsible for the combination of movement and peripheral nerve disorders as a unique entity, some of which are potentially treatable, including paraneoplastic, autoimmune and nutritional aetiologies. Finally, genetic causes should be pursued in case of positive family history, young onset or multisystemic involvement, and examined for neuroacanthocytosis, spinocerebellar ataxias, mitochondrial disorders and less common causes of adult-onset cerebellar ataxias and spastic paraparesis. Deep phenotyping in terms of neurological and general examination, as well as laboratory tests, neuroimaging, neurophysiology, and next-generation genetic analysis, may guide the clinician toward the correct diagnosis and management.
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14
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Screening for RFC-1 pathological expansion in late-onset ataxias: a contribution to the differential diagnosis. J Neurol 2022; 269:5431-5435. [PMID: 35633373 DOI: 10.1007/s00415-022-11192-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Revised: 05/10/2022] [Accepted: 05/12/2022] [Indexed: 10/18/2022]
Abstract
We screened 62 late-onset ataxia patients for the AAGGG pathological expansion in the RFC-1 gene that, when biallelic, causes Cerebellar Ataxia, Neuropathy, Vestibular Areflexia Syndrome (CANVAS). Nine patients tested positive. Six had a previous diagnosis of sporadic adult-onset ataxia (SAOA) and three of multisystem atrophy type C (MSA-C). Further six patients were heterozygous for the pathological RFC-1 expansion, four with an initial diagnosis of MSA-C and two of SAOA. In comparison with CANVAS, MSA-C patients had faster progression and shorter disease duration to walking with aids. An abnormal DaTscan does not seem to contribute to differential diagnosis between CANVAS and MSA-C.
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