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Shukla S, Gupta K, Singh K, Mishra A, Kumar A. An Updated Canvas of the RFC1-mediated CANVAS (Cerebellar Ataxia, Neuropathy and Vestibular Areflexia Syndrome). Mol Neurobiol 2024:10.1007/s12035-024-04307-0. [PMID: 38898197 DOI: 10.1007/s12035-024-04307-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2024] [Accepted: 06/13/2024] [Indexed: 06/21/2024]
Abstract
Proliferation of specific nucleotide sequences within the coding and non-coding regions of numerous genes has been implicated in approximately 40 neurodegenerative disorders. Cerebellar ataxia, neuropathy and vestibular areflexia syndrome (CANVAS), a neurodegenerative disorder, is distinguished by a pathological triad of sensory neuropathy, bilateral vestibular areflexia and cerebellar impairments. It manifests in adults gradually and is autosomal recessive and multi-system ataxia. Predominantly, CANVAS is associated with biallelic AAGGG repeat expansions in intron 2 of the RFC1 gene. Although various motifs have been identified, only a subset induces pathological consequences, by forming stable secondary structures that disrupt gene functions both in vitro and in vivo. The pathogenesis of CANVAS remains a subject of intensive research, yet its precise mechanisms remain elusive. Herein, we aim to comprehensively review the epidemiology, clinical ramifications, molecular mechanisms, genetics, and potential therapeutics in light of the current findings, extending an overview of the most significant research on CANVAS.
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Affiliation(s)
- Sakshi Shukla
- Department of Biosciences and Biomedical Engineering, Indian Institute of Technology Indore, Simrol, Indore, 453552, India
| | - Kanav Gupta
- Department of Biosciences and Biomedical Engineering, Indian Institute of Technology Indore, Simrol, Indore, 453552, India
| | - Krishna Singh
- Department of Biosciences and Biomedical Engineering, Indian Institute of Technology Indore, Simrol, Indore, 453552, India
| | - Amit Mishra
- Cellular and Molecular Neurobiology Unit, Indian Institute of Technology, Jodhpur, Rajasthan, 342037, India
| | - Amit Kumar
- Department of Biosciences and Biomedical Engineering, Indian Institute of Technology Indore, Simrol, Indore, 453552, India.
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2
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Votsi C, Tomazou M, Nicolaou P, Pantzaris MC, Pitsas G, Adamou A, Kleopa KA, Zamba-Papanicolaou E, Christodoulou K. RFC1 Repeat Distribution in the Cypriot Population: Study of a Large Cohort of Patients With Undiagnosed Ataxia and Non-Disease Controls. Neurol Genet 2024; 10:e200149. [PMID: 38685975 PMCID: PMC11057437 DOI: 10.1212/nxg.0000000000200149] [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: 11/17/2023] [Accepted: 02/20/2024] [Indexed: 05/02/2024]
Abstract
Background and Objectives The intronic biallelic AAGGG expansion in the replication factor C subunit 1 (RFC1) gene was recently associated with a phenotype combining cerebellar ataxia, neuropathy, and vestibular areflexia syndrome, as well as with late-onset ataxia. Following this discovery, studies in multiple populations extended the phenotypic and genotypic spectrum of this locus. Multiple benign and additional pathogenic configurations are currently known. Our main objectives were to study the prevalence of the pathogenic AAGGG expansion in the Cypriot population, to further characterize the RFC1 repeat locus allele distribution, and to search for possible novel repeat configurations. Methods Cypriot undiagnosed patients, in the majority presenting at least with cerebellar ataxia and non-neurologic disease controls, were included in this study. A combination of conventional methods was used, including standard PCR flanking the repeat region, repeat-primed PCR, long-range PCR, and Sanger sequencing. Bioinformatics analysis of already available in-house short-read whole-genome sequencing data was also performed. Results A large group of undiagnosed patients (n = 194), mainly presenting with pure ataxia or with ataxia accompanied by neuropathy or additional symptoms, as well as a group of non-disease controls (n = 100), were investigated in the current study. Our findings include the diagnosis of 10 patients homozygous for the pathogenic AAGGG expansion and a high percentage of heterozygous AAGGG carriers in both groups. The benign AAAAGn, AAAGGn, and AAGAGn configurations were also identified in our cohorts. We also report and discuss the identification of 2 recently reported novel and possibly benign repeat configurations, AAAGGGn and AAGACn, thus confirming their existence in another distinct population, and we highlight an increased frequency of the AAAGGGn in the patient group, including a single case of homozygosity. Discussion Our findings indicate the existence of genetic heterogeneity regarding the RFC1 repeat configurations and that the AAGGG pathogenic expansion is a frequent cause of ataxia in the Cypriot population.
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Affiliation(s)
- Christina Votsi
- From the Neurogenetics Department (C.V., P.N., K.C.); Bioinformatics Department (M.T.); Neuroimmunology Department (M.C.P., G.P.); Neuroepidemiology Department (A.A.); Neuroscience Department and Center for Neuromascular Disorders (K.A.K.); and Neuroepidemiology Department and Center for Neuromascular Disorders (E.Z.-P.), The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus
| | - Marios Tomazou
- From the Neurogenetics Department (C.V., P.N., K.C.); Bioinformatics Department (M.T.); Neuroimmunology Department (M.C.P., G.P.); Neuroepidemiology Department (A.A.); Neuroscience Department and Center for Neuromascular Disorders (K.A.K.); and Neuroepidemiology Department and Center for Neuromascular Disorders (E.Z.-P.), The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus
| | - Paschalis Nicolaou
- From the Neurogenetics Department (C.V., P.N., K.C.); Bioinformatics Department (M.T.); Neuroimmunology Department (M.C.P., G.P.); Neuroepidemiology Department (A.A.); Neuroscience Department and Center for Neuromascular Disorders (K.A.K.); and Neuroepidemiology Department and Center for Neuromascular Disorders (E.Z.-P.), The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus
| | - Marios C Pantzaris
- From the Neurogenetics Department (C.V., P.N., K.C.); Bioinformatics Department (M.T.); Neuroimmunology Department (M.C.P., G.P.); Neuroepidemiology Department (A.A.); Neuroscience Department and Center for Neuromascular Disorders (K.A.K.); and Neuroepidemiology Department and Center for Neuromascular Disorders (E.Z.-P.), The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus
| | - Giorgos Pitsas
- From the Neurogenetics Department (C.V., P.N., K.C.); Bioinformatics Department (M.T.); Neuroimmunology Department (M.C.P., G.P.); Neuroepidemiology Department (A.A.); Neuroscience Department and Center for Neuromascular Disorders (K.A.K.); and Neuroepidemiology Department and Center for Neuromascular Disorders (E.Z.-P.), The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus
| | - Archontia Adamou
- From the Neurogenetics Department (C.V., P.N., K.C.); Bioinformatics Department (M.T.); Neuroimmunology Department (M.C.P., G.P.); Neuroepidemiology Department (A.A.); Neuroscience Department and Center for Neuromascular Disorders (K.A.K.); and Neuroepidemiology Department and Center for Neuromascular Disorders (E.Z.-P.), The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus
| | - Kleopas A Kleopa
- From the Neurogenetics Department (C.V., P.N., K.C.); Bioinformatics Department (M.T.); Neuroimmunology Department (M.C.P., G.P.); Neuroepidemiology Department (A.A.); Neuroscience Department and Center for Neuromascular Disorders (K.A.K.); and Neuroepidemiology Department and Center for Neuromascular Disorders (E.Z.-P.), The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus
| | - Eleni Zamba-Papanicolaou
- From the Neurogenetics Department (C.V., P.N., K.C.); Bioinformatics Department (M.T.); Neuroimmunology Department (M.C.P., G.P.); Neuroepidemiology Department (A.A.); Neuroscience Department and Center for Neuromascular Disorders (K.A.K.); and Neuroepidemiology Department and Center for Neuromascular Disorders (E.Z.-P.), The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus
| | - Kyproula Christodoulou
- From the Neurogenetics Department (C.V., P.N., K.C.); Bioinformatics Department (M.T.); Neuroimmunology Department (M.C.P., G.P.); Neuroepidemiology Department (A.A.); Neuroscience Department and Center for Neuromascular Disorders (K.A.K.); and Neuroepidemiology Department and Center for Neuromascular Disorders (E.Z.-P.), The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus
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3
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Milovanović A, Dragaševic‐Mišković N, Thomsen M, Borsche M, Hinrichs F, Westenberger A, Klein C, Brüggemann N, Branković M, Marjanović A, Svetel M, Kostić VS, Lohmann K. RFC1 and FGF14 Repeat Expansions in Serbian Patients with Cerebellar Ataxia. Mov Disord Clin Pract 2024; 11:626-633. [PMID: 38487929 PMCID: PMC11145142 DOI: 10.1002/mdc3.14020] [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: 10/06/2023] [Revised: 01/26/2024] [Accepted: 02/21/2024] [Indexed: 06/04/2024] Open
Abstract
BACKGROUND The newly discovered intronic repeat expansions in the genes encoding replication factor C subunit 1 (RFC1) and fibroblast growth factor 14 (FGF14) frequently cause late-onset cerebellar ataxia. OBJECTIVES To investigate the presence of RFC1 and FGF14 pathogenic repeat expansions in Serbian patients with adult-onset cerebellar ataxia. METHODS The study included 167 unrelated patients with sporadic or familial cerebellar ataxia. The RFC1 repeat expansion analysis was performed by duplex PCR and Sanger sequencing, while the FGF14 repeat expansion was tested for by long-range PCR, repeat-primed PCR, and Sanger sequencing. RESULTS We identified pathogenic repeat expansions in RFC1 in seven patients (7/167; 4.2%) with late-onset sporadic ataxia with neuropathy and chronic cough. Two patients also had bilateral vestibulopathy. Repeat expansions in FGF14 were found in nine unrelated patients (9/167; 5.4%) with ataxia, less than half of whom presented with neuropathy and two-thirds with global brain atrophy. Tremor and episodic features were the most frequent additional characteristics in carriers of uninterrupted FGF14 repeat expansions. Among the 122 sporadic cases, 12 (9.8%) carried an expansion in either RFC1 or FGF14, comparable to 4/45 (8.9%) among the patients with a positive family history. CONCLUSIONS Pathogenic repeat expansions in RFC1 and FGF14 are relatively frequent causes of adult-onset cerebellar ataxia, especially among sporadic patients, indicating that family history should not be considered when prioritizing ataxia patients for testing of RFC1 or FGF14 repeat expansions.
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Affiliation(s)
| | - Nataša Dragaševic‐Mišković
- Neurology ClinicUniversity Clinical Center of SerbiaBelgradeSerbia
- Medical FacultyUniversity BelgradeBelgradeSerbia
| | - Mirja Thomsen
- Institute of NeurogeneticsUniversity of LübeckLübeckGermany
| | - Max Borsche
- Institute of NeurogeneticsUniversity of LübeckLübeckGermany
- Department of NeurologyUniversity of Lübeck and University Hospital Schleswig‐Holstein, Campus LübeckLübeckGermany
| | | | | | | | - Norbert Brüggemann
- Institute of NeurogeneticsUniversity of LübeckLübeckGermany
- Department of NeurologyUniversity of Lübeck and University Hospital Schleswig‐Holstein, Campus LübeckLübeckGermany
| | - Marija Branković
- Neurology ClinicUniversity Clinical Center of SerbiaBelgradeSerbia
| | - Ana Marjanović
- Neurology ClinicUniversity Clinical Center of SerbiaBelgradeSerbia
| | - Marina Svetel
- Neurology ClinicUniversity Clinical Center of SerbiaBelgradeSerbia
- Medical FacultyUniversity BelgradeBelgradeSerbia
| | - Vladimir S. Kostić
- Neurology ClinicUniversity Clinical Center of SerbiaBelgradeSerbia
- Medical FacultyUniversity BelgradeBelgradeSerbia
| | - Katja Lohmann
- Institute of NeurogeneticsUniversity of LübeckLübeckGermany
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4
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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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5
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Kartanou C, Mitrousias A, Pellerin D, Kontogeorgiou Z, Iruzubieta P, Dicaire MJ, Danzi MC, Koniari C, Athanassopoulos K, Panas M, Stefanis L, Zuchner S, Brais B, Houlden H, Karadima G, Koutsis G. The FGF14 GAA repeat expansion in Greek patients with late-onset cerebellar ataxia and an overview of the SCA27B phenotype across populations. Clin Genet 2024; 105:446-452. [PMID: 38221848 DOI: 10.1111/cge.14482] [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: 11/06/2023] [Revised: 12/30/2023] [Accepted: 01/03/2024] [Indexed: 01/16/2024]
Abstract
A pathogenic GAA repeat expansion in the first intron of the fibroblast growth factor 14 gene (FGF14) has been recently identified as the cause of spinocerebellar ataxia 27B (SCA27B). We herein screened 160 Greek index cases with late-onset cerebellar ataxia (LOCA) for FGF14 repeat expansions using a combination of long-range PCR and bidirectional repeat-primed PCRs. We identified 19 index cases (12%) carrying a pathogenic FGF14 GAA expansion, a diagnostic yield higher than that of previously screened repeat-expansion ataxias in Greek LOCA patients. The age at onset of SCA27B patients was 60.5 ± 12.3 years (range, 34-80). Episodic onset (37%), downbeat nystagmus (32%) and vertigo (26%) were significantly more frequent in FGF14 expansion-positive cases compared to expansion-negative cases. Beyond typical cerebellar signs, SCA27B patients often displayed hyperreflexia (47%) and reduced vibration sense in the lower extremities (42%). The frequency and phenotypic profile of SCA27B in Greek patients was similar to most other previously studied populations. We conclude that FGF14 GAA repeat expansions are the commonest known genetic cause of LOCA in the Greek population and recommend prioritizing testing for FGF14 expansions in the diagnostic algorithm of patients with LOCA.
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Affiliation(s)
- Chrisoula Kartanou
- Neurogenetics Unit, 1st Department of Neurology, National and Kapodistrian University of Athens, Eginitio Hospital, Athens, Greece
| | - Alexandros Mitrousias
- Neurogenetics Unit, 1st Department of Neurology, National and Kapodistrian University of Athens, Eginitio Hospital, Athens, Greece
| | - David Pellerin
- Department of Neurology and Neurosurgery, Montreal Neurological Hospital and Institute, McGill University, Montreal, Québec, Canada
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology London and The National Hospital for Neurology and Neurosurgery, University College London, London, UK
| | - Zoi Kontogeorgiou
- Neurogenetics Unit, 1st Department of Neurology, National and Kapodistrian University of Athens, Eginitio Hospital, Athens, Greece
| | - Pablo Iruzubieta
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology London and The National Hospital for Neurology and Neurosurgery, University College London, London, UK
- Department of Neurology, Donostia University Hospital, Biogipuzkoa Health Research Institute, Donostia-San Sebastián, Spain
- CIBERNED Centro de Investigación Biomédica en Red en Enfermedades Neurodegenerativas-Instituto de Salud Carlos III (CIBER-CIBERNED-ISCIII), Madrid, Spain
| | - Marie-Josée Dicaire
- Department of Neurology and Neurosurgery, Montreal Neurological Hospital and Institute, McGill University, Montreal, Québec, Canada
| | - Matt C Danzi
- Dr. John T. Macdonald Foundation Department of Human Genetics and John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Chrysoula Koniari
- Neurogenetics Unit, 1st Department of Neurology, National and Kapodistrian University of Athens, Eginitio Hospital, Athens, Greece
| | - Konstantinos Athanassopoulos
- Neurogenetics Unit, 1st Department of Neurology, National and Kapodistrian University of Athens, Eginitio Hospital, Athens, Greece
| | - Marios Panas
- Neurogenetics Unit, 1st Department of Neurology, National and Kapodistrian University of Athens, Eginitio Hospital, Athens, Greece
| | - Leonidas Stefanis
- 1st Department of Neurology, National and Kapodistrian University of Athens, Eginitio Hospital, Athens, Greece
| | - Stephan Zuchner
- Dr. John T. Macdonald Foundation Department of Human Genetics and John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Bernard Brais
- Department of Neurology and Neurosurgery, Montreal Neurological Hospital and Institute, McGill University, Montreal, Québec, Canada
- Department of Human Genetics, McGill University, Montreal, Québec, Canada
| | - Henry Houlden
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology London and The National Hospital for Neurology and Neurosurgery, University College London, London, UK
| | - Georgia Karadima
- Neurogenetics Unit, 1st Department of Neurology, National and Kapodistrian University of Athens, Eginitio Hospital, Athens, Greece
| | - Georgios Koutsis
- Neurogenetics Unit, 1st Department of Neurology, National and Kapodistrian University of Athens, Eginitio Hospital, Athens, Greece
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6
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Lobo CC, Wertheimer GS, Schmitt GS, Matos PC, Rezende TJ, Silva JM, Borba FC, Lima FD, Martinez AR, Barsottini OG, Pedroso JL, Marques W, França MC. Cranial Nerve Thinning Distinguishes RFC1-Related Disorder from Other Late-Onset Ataxias. Mov Disord Clin Pract 2024; 11:45-52. [PMID: 38291837 PMCID: PMC10828611 DOI: 10.1002/mdc3.13930] [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: 06/22/2023] [Revised: 10/11/2023] [Accepted: 11/04/2023] [Indexed: 02/01/2024] Open
Abstract
BACKGROUND RFC1-related disorder (RFC1/CANVAS) shares clinical features with other late-onset ataxias, such as spinocerebellar ataxias (SCA) and multiple system atrophy cerebellar type (MSA-C). Thinning of cranial nerves V (CNV) and VIII (CNVIII) has been reported in magnetic resonance imaging (MRI) scans of RFC1/CANVAS, but its specificity remains unclear. OBJECTIVES To assess the usefulness of CNV and CNVIII thinning to differentiate RFC1/CANVAS from SCA and MSA-C. METHODS Seventeen individuals with RFC1/CANVAS, 57 with SCA (types 2, 3 and 6), 11 with MSA-C and 15 healthy controls were enrolled. The Balanced Fast Field Echo sequence was used for assessment of cranial nerves. Images were reviewed by a neuroradiologist, who classified these nerves as atrophic or normal, and subsequently the CNV was segmented manually by an experienced neurologist. Both assessments were blinded to patient and clinical data. Non-parametric tests were used to assess between-group comparisons. RESULTS Atrophy of CNV and CNVIII, both alone and in combination, was significantly more frequent in the RFC1/CANVAS group than in healthy controls and all other ataxia groups. Atrophy of CNV had the highest sensitivity (82%) and combined CNV and CNVIII atrophy had the best specificity (92%) for diagnosing RFC1/CANVAS. In the quantitative analyses, CNV was significantly thinner in the RFC1/CANVAS group relative to all other groups. The cutoff CNV diameter that best identified RFC1/CANVAS was ≤2.2 mm (AUC = 0.91; sensitivity 88.2%, specificity 95.6%). CONCLUSION MRI evaluation of CNV and CNVIII using a dedicated sequence is an easy-to-use tool that helps to distinguish RFC1/CANVAS from SCA and MSA-C.
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Affiliation(s)
- Camila C. Lobo
- Department of Neurology, School of Medical SciencesUniversity of Campinas (UNICAMP)CampinasBrazil
| | | | - Gabriel S. Schmitt
- Department of Neurology, School of Medical SciencesUniversity of Campinas (UNICAMP)CampinasBrazil
| | - Paula C.A.A.P. Matos
- Department of Neurology and Neurosurgery, School of MedicineFederal University of São Paulo (UNIFESP)São PauloBrazil
| | - Thiago J.R. Rezende
- Department of Neurology, School of Medical SciencesUniversity of Campinas (UNICAMP)CampinasBrazil
| | - Joyce M. Silva
- Department of Neurology, School of Medical SciencesUniversity of Campinas (UNICAMP)CampinasBrazil
| | - Fabrício C. Borba
- Department of Neurology, School of Medical SciencesUniversity of Campinas (UNICAMP)CampinasBrazil
| | - Fabrício D. Lima
- Department of Neurology, School of Medical SciencesUniversity of Campinas (UNICAMP)CampinasBrazil
| | - Alberto R.M. Martinez
- Department of Neurology, School of Medical SciencesUniversity of Campinas (UNICAMP)CampinasBrazil
| | - Orlando G.P. Barsottini
- Department of Neurology and Neurosurgery, School of MedicineFederal University of São Paulo (UNIFESP)São PauloBrazil
| | - José Luiz Pedroso
- Department of Neurology and Neurosurgery, School of MedicineFederal University of São Paulo (UNIFESP)São PauloBrazil
| | - Wilson Marques
- Department of Neurosciences, School of MedicineUniversity of São Paulo at Ribeirão Preto (USP‐RP)Ribeirão PretoBrazil
| | - Marcondes C. França
- Department of Neurology, School of Medical SciencesUniversity of Campinas (UNICAMP)CampinasBrazil
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7
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Scriba CK, Stevanovski I, Chintalaphani SR, Gamaarachchi H, Ghaoui R, Ghia D, Henderson RD, Jordan N, Winkel A, Lamont PJ, Rodrigues MJ, Roxburgh RH, Weisburd B, Laing NG, Deveson IW, Davis MR, Ravenscroft G. RFC1 in an Australasian neurological disease cohort: extending the genetic heterogeneity and implications for diagnostics. Brain Commun 2023; 5:fcad208. [PMID: 37621409 PMCID: PMC10445415 DOI: 10.1093/braincomms/fcad208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 06/04/2023] [Accepted: 07/25/2023] [Indexed: 08/26/2023] Open
Abstract
Cerebellar ataxia, neuropathy and vestibular areflexia syndrome is a progressive, generally late-onset, neurological disorder associated with biallelic pentanucleotide expansions in Intron 2 of the RFC1 gene. The locus exhibits substantial genetic variability, with multiple pathogenic and benign pentanucleotide repeat alleles previously identified. To determine the contribution of pathogenic RFC1 expansions to neurological disease within an Australasian cohort and further investigate the heterogeneity exhibited at the locus, a combination of flanking and repeat-primed PCR was used to screen a cohort of 242 Australasian patients with neurological disease. Patients whose data indicated large gaps within expanded alleles following repeat-primed PCR, underwent targeted long-read sequencing to identify novel repeat motifs at the locus. To increase diagnostic yield, additional probes at the RFC1 repeat region were incorporated into the PathWest diagnostic laboratory targeted neurological disease gene panel to enable first-pass screening of the locus for all samples tested on the panel. Within the Australasian cohort, we detected known pathogenic biallelic expansions in 15.3% (n = 37) of patients. Thirty indicated biallelic AAGGG expansions, two had biallelic 'Māori alleles' [(AAAGG)exp(AAGGG)exp], two samples were compound heterozygous for the Māori allele and an AAGGG expansion, two samples had biallelic ACAGG expansions and one sample was compound heterozygous for the ACAGG and AAGGG expansions. Forty-five samples tested indicated the presence of biallelic expansions not known to be pathogenic. A large proportion (84%) showed complex interrupted patterns following repeat-primed PCR, suggesting that these expansions are likely to be comprised of more than one repeat motif, including previously unknown repeats. Using targeted long-read sequencing, we identified three novel repeat motifs in expanded alleles. Here, we also show that short-read sequencing can be used to reliably screen for the presence or absence of biallelic RFC1 expansions in all samples tested using the PathWest targeted neurological disease gene panel. Our results show that RFC1 pathogenic expansions make a substantial contribution to neurological disease in the Australasian population and further extend the heterogeneity of the locus. To accommodate the increased complexity, we outline a multi-step workflow utilizing both targeted short- and long-read sequencing to achieve a definitive genotype and provide accurate diagnoses for patients.
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Affiliation(s)
- Carolin K Scriba
- Rare Genetic Diseases and Functional Genomics Group, Centre for Medical Research, University of Western Australia, Harry Perkins Institute of Medical Research, QEII Medical Centre, Nedlands, WA 6009, Australia
- Neurogenetics Laboratory, Department of Diagnostic Genomics, PP Block, QEII Medical Centre, Nedlands, WA 6009, Australia
| | - Igor Stevanovski
- Genomics Pillar, Garvan Institute of Medical Research, Sydney, NSW 2010, Australia
- Centre for Population Genomics, Garvan Institute of Medical Research and Murdoch Children’s Research Institute, Sydney, NSW 2010, Australia
| | - Sanjog R Chintalaphani
- Genomics Pillar, Garvan Institute of Medical Research, Sydney, NSW 2010, Australia
- Centre for Population Genomics, Garvan Institute of Medical Research and Murdoch Children’s Research Institute, Sydney, NSW 2010, Australia
- School of Clinical Medicine, Faculty of Medicine and Health, University of New South Wales, Sydney, NSW 2050, Australia
| | - Hasindu Gamaarachchi
- Genomics Pillar, Garvan Institute of Medical Research, Sydney, NSW 2010, Australia
- Centre for Population Genomics, Garvan Institute of Medical Research and Murdoch Children’s Research Institute, Sydney, NSW 2010, Australia
- School of Computer Science and Engineering, University of New South Wales, Sydney, NSW 2052, Australia
| | - Roula Ghaoui
- Department of Neurology, Royal Adelaide Hospital, Adelaide, SA 5000, Australia
- Adelaide Medical School, Faculty of Health and Medical Sciences, University of Adelaide, Adelaide, SA 5000, Australia
| | - Darshan Ghia
- UWA Medical School, University of Western Australia, Perth, WA 6009, Australia
- Neurology and Stroke Unit, Fiona Stanley Hospital, Murdoch, WA 6150, Australia
| | - Robert D Henderson
- Centre for Clinical Research, University of Queensland, Herston, QLD 4006, Australia
| | - Nerissa Jordan
- Department of Neurology, Fiona Stanley Hospital, Perth, WA 6150, Australia
| | - Antony Winkel
- Department of Neurosciences, Griffith University, Sunshine Coast University Hospital, Mount Gravatt, QLD 4111, Australia
| | | | | | - Richard H Roxburgh
- Centre for Brain Research Neurogenetics Research Clinic, University of Auckland, Auckland, New Zealand
| | - Ben Weisburd
- Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Nigel G Laing
- Preventive Genetics Group, Centre for Medical Research, University of Western Australia, Harry Perkins Institute of Medical Research, QEII Medical Centre, Nedlands, WA 6009, Australia
| | - Ira W Deveson
- Genomics Pillar, Garvan Institute of Medical Research, Sydney, NSW 2010, Australia
- Centre for Population Genomics, Garvan Institute of Medical Research and Murdoch Children’s Research Institute, Sydney, NSW 2010, Australia
- School of Clinical Medicine, Faculty of Medicine and Health, University of New South Wales, Sydney, NSW 2050, Australia
| | - Mark R Davis
- Neurogenetics Laboratory, Department of Diagnostic Genomics, PP Block, QEII Medical Centre, Nedlands, WA 6009, Australia
| | - Gianina Ravenscroft
- Rare Genetic Diseases and Functional Genomics Group, Centre for Medical Research, University of Western Australia, Harry Perkins Institute of Medical Research, QEII Medical Centre, Nedlands, WA 6009, Australia
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8
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Screening for the FMR1 premutation in Greek patients with late-onset movement disorders. Parkinsonism Relat Disord 2023; 107:105253. [PMID: 36549234 DOI: 10.1016/j.parkreldis.2022.105253] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 12/06/2022] [Accepted: 12/18/2022] [Indexed: 12/24/2022]
Abstract
Fragile X-associated tremor/ataxia syndrome (FXTAS) is a late-onset, X-linked, neurodegenerative disorder that affects premutation carriers of the FMR1 gene. FXTAS is often misdiagnosed as spinocerebellar ataxia (SCA) or Parkinson's disease (PD). Herein, we sought to investigate the frequency, genotypic and phenotypic profile of FXTAS in two cohorts of Greek patients with late-onset movement disorders, one with cerebellar ataxia and the other with PD. In total, 90 index patients with late-onset cerebellar ataxia and 171 with PD were selected. None of the cases had male-to-male transmission. Genetic screening for the FMR1 premutation was performed using standard methodology. The FMR1 premutation was detected in two ataxia patients (2.2%) and two PD patients (1.2%). Additional clinical features in FXTAS patients from the ataxia cohort included neuropathy, mild parkinsonism, cognitive impairment and pyramidal signs. The FXTAS patients from the PD cohort had typical PD. We conclude that, in the Greek population, the FMR1 premutation is an important, albeit rare, cause of late-onset movement disorders. Routine premutation screening should be considered in SCA panel-negative late-onset ataxia cases. Directed premutation screening should be considered in all ataxia and PD cases with additional features suggestive of FXTAS. Our study highlights the importance of FMR1 genetic testing in the diagnosis of late-onset movement disorders.
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9
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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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10
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Yuan JH, Higuchi Y, Ando M, Matsuura E, Hashiguchi A, Yoshimura A, Nakamura T, Sakiyama Y, Mitsui J, Ishiura H, Tsuji S, Takashima H. Multi-type RFC1 repeat expansions as the most common cause of hereditary sensory and autonomic neuropathy. Front Neurol 2022; 13:986504. [PMID: 36061987 PMCID: PMC9428154 DOI: 10.3389/fneur.2022.986504] [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: 07/05/2022] [Accepted: 07/27/2022] [Indexed: 11/24/2022] Open
Abstract
Non-coding repeat expansions within RFC1 and NOTCH2NLC genes have lately been linked to multisystem neurodegenerative diseases, which also shed light on yet undiagnosed patients with inherited peripheral neuropathies. The aim of this study was to identify the genetic basis of patients with hereditary sensory and autonomic neuropathy (HSAN). We collected 79 unrelated DNA samples clinically suspected with HSAN from multiple regions of Japan. Mutation screening was first performed using gene panel sequencing and whole-exome sequencing. Pathogenic/likely pathogenic variants were identified from genes of WNK1/HSN2 (6 cases), SCN9A (3 cases), NTRK1 (3 cases), and DNMT1 (2 cases). Subsequently, long-range flanking PCR and repeat-primed PCR were applied to analyze repeat expansions in RFC1 and NOTCH2NLC. Bi-allelic RFC1 repeat expansions were detected from 20 adult-onset HSAN patients, consisting of [(AAGGG)exp/(AAGGG)exp] (8 cases), [(ACAGG)exp/(ACAGG)exp] (8 cases), and [(AAGGG)exp/(ACAGG)exp] (4 cases). GGC repeat expansion in NOTCH2NLC was found in 1 case. Single-nucleotide variant-based haplotype analysis of patients harboring disease-associated repeat expansions in RFC1 revealed distinguishable haplotypes among subgroups with different repeat genotypes. These findings substantially redefine the genetic spectrum of HSAN, where multi-type RFC1 repeat expansions account for 25.3% of all patients, highlighting the necessity of genetic screening, particularly for adult-onset patients.
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Affiliation(s)
- Jun-Hui Yuan
- Department of Neurology and Geriatrics, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Yujiro Higuchi
- Department of Neurology and Geriatrics, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Masahiro Ando
- Department of Neurology and Geriatrics, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Eiji Matsuura
- Department of Neurology and Geriatrics, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Akihiro Hashiguchi
- Department of Neurology and Geriatrics, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Akiko Yoshimura
- Department of Neurology and Geriatrics, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Tomonori Nakamura
- Department of Neurology and Geriatrics, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Yusuke Sakiyama
- Department of Neurology and Geriatrics, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Jun Mitsui
- Department of Molecular Neurology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Hiroyuki Ishiura
- Department of Neurology, Faculty of Medicine, The University of Tokyo, Tokyo, Japan
| | - Shoji Tsuji
- Department of Molecular Neurology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
- Institute of Medical Genomics, International University of Health and Welfare, Chiba, Japan
| | - Hiroshi Takashima
- Department of Neurology and Geriatrics, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
- *Correspondence: Hiroshi Takashima
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11
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Ando M, Higuchi Y, Yuan JH, Yoshimura A, Higashi S, Takeuchi M, Hobara T, Kojima F, Noguchi Y, Takei J, Hiramatsu Y, Nozuma S, Sakiyama Y, Hashiguchi A, Matsuura E, Okamoto Y, Nagai M, Takashima H. Genetic and clinical features of cerebellar ataxia with RFC1 biallelic repeat expansions in Japan. Front Neurol 2022; 13:952493. [PMID: 36034314 PMCID: PMC9404689 DOI: 10.3389/fneur.2022.952493] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Accepted: 06/28/2022] [Indexed: 11/19/2022] Open
Abstract
The recessive intronic pentanucleotide repeat AAGGG expansion of replication factor complex subunit 1 (RFC1) is associated with cerebellar ataxia, sensory neuropathy, and vestibular areflexia syndrome. And the clinical spectrum has been continuously expanding. We conducted this study to demonstrate the clinical and genetic features of a large-scale case series of Japanese patients with cerebellar ataxia with RFC1 repeat expansions. We examined 1,289 Japanese patients with cerebellar ataxia and analyzed RFC1 repeat expansions in 840 patients, excluding those with genetic diagnoses or an autosomal dominant inheritance pattern. For individuals where no product was obtained by flanking polymerase chain reaction (PCR), repeat-primed PCR was performed using primers specific for the following four repeat motifs: AAAAG, AAAGG, AAGGG, and ACAGG. RFC1 analysis revealed multitype biallelic pathogenic repeat expansions in 15 patients, including (AAGGG)exp/(AAGGG)exp in seven patients, (ACAGG)exp/(ACAGG)exp in three patients, (AAGGG)exp/(ACAGG)exp in four patients, and (AAGGG)exp/(AAAGG)15(AAGGG)exp in one patient. Clinical analysis showed various combinations of cerebellar ataxia, vestibular dysfunction, neuropathy, cognitive decline, autonomic dysfunction, chronic cough, pyramidal tract disorder, parkinsonism, involuntary movement, and muscle fasciculation. Pathological RFC1 repeat expansions account for 1.8% (15/840) of undiagnosed patients with cerebellar ataxia and sporadic/recessive/unclassified inheritance. Screening of RFC1 repeat expansions should be considered in patients with cerebellar ataxia, irrespective of their subtype and onset age.
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Affiliation(s)
- Masahiro Ando
- Department of Neurology and Geriatrics, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Yujiro Higuchi
- Department of Neurology and Geriatrics, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Junhui H. Yuan
- Department of Neurology and Geriatrics, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Akiko Yoshimura
- Department of Neurology and Geriatrics, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Shuntaro Higashi
- School of Medicine, Faculty of Medicine, Kagoshima University, Kagoshima, Japan
| | - Mika Takeuchi
- Department of Neurology and Geriatrics, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Takahiro Hobara
- Department of Neurology and Geriatrics, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Fumikazu Kojima
- Department of Neurology and Geriatrics, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Yutaka Noguchi
- Department of Neurology and Geriatrics, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Jun Takei
- Department of Neurology and Geriatrics, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Yu Hiramatsu
- Department of Neurology and Geriatrics, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Satoshi Nozuma
- Department of Neurology and Geriatrics, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Yusuke Sakiyama
- Department of Neurology and Geriatrics, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Akihiro Hashiguchi
- Department of Neurology and Geriatrics, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Eiji Matsuura
- Department of Neurology and Geriatrics, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Yuji Okamoto
- Department of Neurology and Geriatrics, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
- Department of Physical Therapy, School of Health Sciences, Faculty of Medicine, Kagoshima University, Kagoshima, Japan
| | - Masahiro Nagai
- Department of Neurology and Clinical Pharmacology, Ehime University Hospital, Ehime, Japan
| | - Hiroshi Takashima
- Department of Neurology and Geriatrics, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
- *Correspondence: Hiroshi Takashima
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12
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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: 3] [Impact Index Per Article: 1.5] [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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13
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Mascalchi M, Santorelli FM. The Strange Case of the Multiple MRI Phenotypes of RFC1 Mutation. THE CEREBELLUM 2022; 22:478-481. [PMID: 35359253 DOI: 10.1007/s12311-022-01401-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 03/28/2022] [Indexed: 11/25/2022]
Affiliation(s)
- Mario Mascalchi
- Department of Clinical and Experimental Biomedical Sciences "Mario Serio", University of Florence, Viale Pieraccini 6, 50130, Florence, Italy.
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14
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Miyatake S, Yoshida K, Koshimizu E, Doi H, Yamada M, Miyaji Y, Ueda N, Tsuyuzaki J, Kodaira M, Onoue H, Taguri M, Imamura S, Fukuda H, Hamanaka K, Fujita A, Satoh M, Miyama T, Watanabe N, Kurita Y, Okubo M, Tanaka K, Kishida H, Koyano S, Takahashi T, Ono Y, Higashida K, Yoshikura N, Ogata K, Kato R, Tsuchida N, Uchiyama Y, Miyake N, Shimohata T, Tanaka F, Mizuguchi T, Matsumoto N. Repeat conformation heterogeneity in cerebellar ataxia, neuropathy, vestibular areflexia syndrome. Brain 2022; 145:1139-1150. [PMID: 35355059 DOI: 10.1093/brain/awab363] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Revised: 08/02/2021] [Accepted: 08/24/2021] [Indexed: 12/14/2022] Open
Abstract
Cerebellar ataxia, neuropathy, vestibular areflexia syndrome (CANVAS) is a late-onset, slow-progressing multisystem neurodegenerative disorder. Biallelic AAGGG repeat expansion in RFC1 has been identified as causative of this disease, and repeat conformation heterogeneity (ACAGG repeat) was also recently implied. To molecularly characterize this disease in Japanese patients with adult-onset ataxia, we accumulated and screened 212 candidate families by an integrated approach consisting of flanking PCR, repeat-primed PCR, Southern blotting and long-read sequencing using Sequel II, GridION or PromethION. We identified 16 patients from 11 families, of whom seven had ACAGG expansions [(ACAGG)exp/(ACAGG)exp] (ACAGG homozygotes), two had ACAGG and AAGGG expansions [(ACAGG)exp/(AAGGG)exp] (ACAGG/AAGGG compound heterozygotes) and seven had AAGGG expansions [(AAGGG)exp/(AAGGG)exp] (AAGGG homozygotes). The overall detection rate was 5.2% (11/212 families including one family having two expansion genotypes). Long-read sequencers revealed the entire sequence of both AAGGG and ACAGG repeat expansions at the nucleotide level of resolution. Clinical assessment and neuropathology results suggested that patients with ACAGG expansions have similar clinical features to previously reported patients with homozygous AAGGG expansions, although motor neuron involvement was more notable in patients with ACAGG expansions (even if one allele was involved). Furthermore, a later age of onset and slower clinical progression were implied in patients with ACAGG/AAGGG compound heterozygous expansions compared with either ACAGG or AAGGG homozygotes in our very limited cohort. Our study clearly shows the occurrence of repeat conformation heterogeneity, with possible different impacts on the affected nervous systems. The difference in disease onset and progression between compound heterozygotes and homozygotes might also be suspected but with very limited certainty due to the small sample number of cases in our study. Studies of additional patients are needed to confirm this.
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Affiliation(s)
- Satoko Miyatake
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Kanagawa 236-0004, Japan.,Clinical Genetics Department, Yokohama City University Hospital, Yokohama, Kanagawa 236-0004, Japan
| | - Kunihiro Yoshida
- Division of Neurogenetics, Department of Brain Disease Research, Shinshu University School of Medicine, Matsumoto, Nagano 390-8621, Japan
| | - Eriko Koshimizu
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Kanagawa 236-0004, Japan
| | - Hiroshi Doi
- Department of Neurology and Stroke Medicine, Yokohama City University Graduate School of Medicine, Yokohama, Kanagawa 236-0004, Japan
| | - Mitsunori Yamada
- Division of Neuropathology, Department of Brain Disease Research, Shinshu University School of Medicine, Matsumoto, Nagano 390-8621, Japan
| | - Yosuke Miyaji
- Department of Neurology and Stroke Medicine, Yokohama City University Graduate School of Medicine, Yokohama, Kanagawa 236-0004, Japan
| | - Naohisa Ueda
- Department of Neurology, Yokohama City University Medical Center, Yokohama, Kanagawa 232-0024, Japan
| | - Jun Tsuyuzaki
- Department of Neurology, Asama Nanroku Komoro Medical Center, Komoro, Nagano 384-8588, Japan
| | - Minori Kodaira
- Department of Medicine (Neurology and Rheumatology), Shinshu University School of Medicine, Matsumoto, Nagano 390-8621, Japan
| | - Hiroyuki Onoue
- Department of Neurology, Dokkyo Medical University Saitama Medical Center, Koshigaya, Saitama 343-8555, Japan
| | - Masataka Taguri
- Department of Data Science, Yokohama City University School of Data Science, Yokohama, Kanagawa 236-0027, Japan
| | - Shintaro Imamura
- Fisheries Technology Institute, Japan Fisheries Research and Education Agency, 2-12-4 Fukuura, Kanazawa, Yokohama, Kanagawa, 236-8648, Japan
| | - Hiromi Fukuda
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Kanagawa 236-0004, Japan.,Department of Neurology and Stroke Medicine, Yokohama City University Graduate School of Medicine, Yokohama, Kanagawa 236-0004, Japan
| | - Kohei Hamanaka
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Kanagawa 236-0004, Japan
| | - Atsushi Fujita
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Kanagawa 236-0004, Japan
| | - Mai Satoh
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Kanagawa 236-0004, Japan
| | - Takabumi Miyama
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Kanagawa 236-0004, Japan
| | - Nobuko Watanabe
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Kanagawa 236-0004, Japan
| | - Yusuke Kurita
- Department of Neurology, National Hospital Organization Yokohama Medical Center, Yokohama, Kanagawa 245-8575, Japan
| | - Masaki Okubo
- Department of Neurology and Stroke Medicine, Yokohama City University Graduate School of Medicine, Yokohama, Kanagawa 236-0004, Japan
| | - Kenichi Tanaka
- Department of Neurology and Stroke Medicine, Yokohama City University Graduate School of Medicine, Yokohama, Kanagawa 236-0004, Japan
| | - Hitaru Kishida
- Department of Neurology, Yokohama City University Medical Center, Yokohama, Kanagawa 232-0024, Japan
| | - Shigeru Koyano
- Department of Neurology, Yokohama Minami Kyosai Hospital, Yokohama, Kanagawa 236-0037, Japan
| | - Tatsuya Takahashi
- Department of Neurology, National Hospital Organization Yokohama Medical Center, Yokohama, Kanagawa 245-8575, Japan
| | - Yoya Ono
- Department of Neurology, Gifu University Graduate School of Medicine, Gifu 501-1194, Japan
| | - Kazuhiro Higashida
- Department of Neurology, Gifu University Graduate School of Medicine, Gifu 501-1194, Japan
| | - Nobuaki Yoshikura
- Department of Neurology, Gifu University Graduate School of Medicine, Gifu 501-1194, Japan
| | - Katsuhisa Ogata
- Department of Neurology, National Hospital Organization Higashisaitama National Hospital, Hasuda, Saitama 349-0196, Japan
| | - Rumiko Kato
- Department of Pediatrics, National Hospital Organization Higashisaitama National Hospital, Hasuda, Saitama 349-0196, Japan
| | - Naomi Tsuchida
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Kanagawa 236-0004, Japan.,Department of Rare Disease Genomics, Yokohama City University Hospital, Yokohama, 236-0004, Japan
| | - Yuri Uchiyama
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Kanagawa 236-0004, Japan.,Department of Rare Disease Genomics, Yokohama City University Hospital, Yokohama, 236-0004, Japan
| | - Noriko Miyake
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Kanagawa 236-0004, Japan
| | - Takayoshi Shimohata
- Department of Neurology, Gifu University Graduate School of Medicine, Gifu 501-1194, Japan
| | - Fumiaki Tanaka
- Department of Neurology and Stroke Medicine, Yokohama City University Graduate School of Medicine, Yokohama, Kanagawa 236-0004, Japan
| | - Takeshi Mizuguchi
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Kanagawa 236-0004, Japan
| | - Naomichi Matsumoto
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Kanagawa 236-0004, Japan
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