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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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2
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Bjelica B, Bartels MB, Hesebeck-Brinckmann J, Petri S. Non-motor symptoms in patients with amyotrophic lateral sclerosis: current state and future directions. J Neurol 2024; 271:3953-3977. [PMID: 38805053 PMCID: PMC11233299 DOI: 10.1007/s00415-024-12455-5] [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: 04/17/2024] [Revised: 05/14/2024] [Accepted: 05/16/2024] [Indexed: 05/29/2024]
Abstract
Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by the progressive degeneration of both upper and lower motor neurons. A defining histopathological feature in approximately 97% of all ALS cases is the accumulation of phosphorylated trans-activation response (TAR) DNA-binding protein 43 protein (pTDP-43) aggregates in the cytoplasm of neurons and glial cells within the central nervous system. Traditionally, it was believed that the accumulation of TDP-43 aggregates and subsequent neurodegeneration primarily occurs in motor neurons. However, contemporary evidence suggests that as the disease progresses, other systems and brain regions are also affected. Despite this, there has been a limited number of clinical studies assessing the non-motor symptoms in ALS patients. These studies often employ various outcome measures, resulting in a wide range of reported frequencies of non-motor symptoms in ALS patients. The importance of assessing the non-motor symptoms reflects in a fact that they have a significant impact on patients' quality of life, yet they frequently go underdiagnosed and unreported during clinical evaluations. This review aims to provide an up-to-date overview of the current knowledge concerning non-motor symptoms in ALS. Furthermore, we address their diagnosis and treatment in everyday clinical practice.
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Affiliation(s)
- Bogdan Bjelica
- Department of Neurology, Hannover Medical School, 1, Carl-Neuberg-Strasse, 30625, Hannover, Germany.
| | - Maj-Britt Bartels
- Precision Neurology of Neuromuscular and Motoneuron Diseases, University of Luebeck, Lübeck, Germany
| | - Jasper Hesebeck-Brinckmann
- Neurology Department, Division for Neurodegenerative Diseases, University Medicine Mannheim, Heidelberg University, Mannheim Center for Translational Medicine, Mannheim, Germany
| | - Susanne Petri
- Department of Neurology, Hannover Medical School, 1, Carl-Neuberg-Strasse, 30625, Hannover, Germany
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3
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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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4
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Quartesan I, Vegezzi E, Currò R, Heslegrave A, Pisciotta C, Iruzubieta P, Salvalaggio A, Fernández‐Eulate G, Dominik N, Rugginini B, Manini A, Abati E, Facchini S, Manso K, Albajar I, Laban R, Rossor AM, Pichiecchio A, Cosentino G, Saveri P, Salsano E, Andreetta F, Valente EM, Zetterberg H, Giunti P, Stojkovic T, Briani C, López de Munain A, Pareyson D, Reilly MM, Houlden H, Tassorelli C, Cortese A. Serum Neurofilament Light Chain in Replication Factor Complex Subunit 1 CANVAS and Disease Spectrum. Mov Disord 2024; 39:209-214. [PMID: 38054570 PMCID: PMC10953432 DOI: 10.1002/mds.29680] [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: 08/11/2023] [Revised: 11/07/2023] [Accepted: 11/15/2023] [Indexed: 12/07/2023] Open
Abstract
BACKGROUND Biallelic intronic AAGGG repeat expansions in the replication factor complex subunit 1 (RFC1) gene were identified as the leading cause of cerebellar ataxia, neuropathy, vestibular areflexia syndrome. Patients exhibit significant clinical heterogeneity and variable disease course, but no potential biomarker has been identified to date. OBJECTIVES In this multicenter cross-sectional study, we aimed to evaluate neurofilament light (NfL) chain serum levels in a cohort of RFC1 disease patients and to correlate NfL serum concentrations with clinical phenotype and disease severity. METHODS Sixty-one patients with genetically confirmed RFC1 disease and 48 healthy controls (HCs) were enrolled from six neurological centers. Serum NfL concentration was measured using the single molecule array assay technique. RESULTS Serum NfL concentration was significantly higher in patients with RFC1 disease compared to age- and-sex-matched HCs (P < 0.0001). NfL level showed a moderate correlation with age in both HCs (r = 0.4353, P = 0.0020) and patients (r = 0.4092, P = 0.0011). Mean NfL concentration appeared to be significantly higher in patients with cerebellar involvement compared to patients without cerebellar dysfunction (27.88 vs. 21.84 pg/mL, P = 0.0081). The association between cerebellar involvement and NfL remained significant after controlling for age and sex (β = 0.260, P = 0.034). CONCLUSIONS Serum NfL levels are significantly higher in patients with RFC1 disease compared to HCs and correlate with cerebellar involvement. Longitudinal studies are warranted to assess its change over time.
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Affiliation(s)
- Ilaria Quartesan
- Department of Brain and Behavioral SciencesUniversity of PaviaPaviaItaly
- IRCCS Mondino FoundationPaviaItaly
| | - Elisa Vegezzi
- Department of Brain and Behavioral SciencesUniversity of PaviaPaviaItaly
- IRCCS Mondino FoundationPaviaItaly
| | - Riccardo Currò
- Department of Brain and Behavioral SciencesUniversity of PaviaPaviaItaly
- Department of Neuromuscular DiseasesUCL Queen Square Institute of NeurologyLondonUnited Kingdom
| | - Amanda Heslegrave
- Department of Neurodegenerative DiseaseUCL Queen Square Institute of NeurologyLondonUnited Kingdom
- UK Dementia Research Institute at UCLLondonUnited Kingdom
| | | | - Pablo Iruzubieta
- Neurology Department, Donostia University HospitalOsakidetza, and Biodonostia Health Research Institute‐UPV‐EHUSan SebastiánSpain
| | | | - Gorka Fernández‐Eulate
- Neuro‐myology Department, Institut de Myologie, Pitié‐Salpêtriére HospitalAPHP, Sorbonne UniversityParisFrance
| | - Natalia Dominik
- Department of Neuromuscular DiseasesUCL Queen Square Institute of NeurologyLondonUnited Kingdom
| | - Bianca Rugginini
- Department of Brain and Behavioral SciencesUniversity of PaviaPaviaItaly
| | - Arianna Manini
- Department of Neuromuscular DiseasesUCL Queen Square Institute of NeurologyLondonUnited Kingdom
- Department of Neurology and Laboratory of NeuroscienceIRCCS Istituto Auxologico ItalianoMilanItaly
| | - Elena Abati
- Department of Neuromuscular DiseasesUCL Queen Square Institute of NeurologyLondonUnited Kingdom
- Department of Pathophysiology and Transplantation (DEPT)University of MilanMilanItaly
| | | | - Katarina Manso
- Clinical Neurochemistry LaboratorySahlgrenska University HospitalMölndalSweden
| | - Ines Albajar
- Neurology Department, Donostia University HospitalOsakidetza, and Biodonostia Health Research Institute‐UPV‐EHUSan SebastiánSpain
| | - Rhiannon Laban
- UK Dementia Research Institute at UCLLondonUnited Kingdom
| | - Alexander M. Rossor
- Department of Neuromuscular DiseasesUCL Queen Square Institute of NeurologyLondonUnited Kingdom
| | - Anna Pichiecchio
- Department of Brain and Behavioral SciencesUniversity of PaviaPaviaItaly
- IRCCS Mondino FoundationPaviaItaly
| | - Giuseppe Cosentino
- Department of Brain and Behavioral SciencesUniversity of PaviaPaviaItaly
- IRCCS Mondino FoundationPaviaItaly
| | - Paola Saveri
- Fondazione IRCCS Istituto Neurologico Carlo BestaMilanItaly
| | - Ettore Salsano
- Fondazione IRCCS Istituto Neurologico Carlo BestaMilanItaly
| | | | - Enza M. Valente
- Department of Brain and Behavioral SciencesUniversity of PaviaPaviaItaly
- IRCCS Mondino FoundationPaviaItaly
| | - Henrik Zetterberg
- Department of Neurodegenerative DiseaseUCL Queen Square Institute of NeurologyLondonUnited Kingdom
- UK Dementia Research Institute at UCLLondonUnited Kingdom
- Clinical Neurochemistry LaboratorySahlgrenska University HospitalMölndalSweden
- Department of Psychiatry and Neurochemistry, Institute of Neuroscience and PhysiologyThe Sahlgrenska Academy at the University of GothenburgMölndalSweden
- Hong Kong Center for Neurodegenerative DiseasesClear Water BayHong KongChina
- Wisconsin Alzheimer's Disease Research Center, University of Wisconsin School of Medicine and Public Health, University of Wisconsin‐MadisonMadisonWisconsinUSA
| | - Paola Giunti
- Department of Clinical and Movement NeuroscienceUCL Queen Square Institute of NeurologyLondonUnited Kingdom
| | - Tanya Stojkovic
- Neuro‐myology Department, Institut de Myologie, Pitié‐Salpêtriére HospitalAPHP, Sorbonne UniversityParisFrance
| | - Chiara Briani
- Department of NeuroscienceUniversity of PadovaPadovaItaly
| | - Adolfo López de Munain
- Neurology Department, Donostia University HospitalOsakidetza, and Biodonostia Health Research Institute‐UPV‐EHUSan SebastiánSpain
| | | | - Mary M. Reilly
- Department of Neuromuscular DiseasesUCL Queen Square Institute of NeurologyLondonUnited Kingdom
| | - Henry Houlden
- Department of Neuromuscular DiseasesUCL Queen Square Institute of NeurologyLondonUnited Kingdom
| | - Cristina Tassorelli
- Department of Brain and Behavioral SciencesUniversity of PaviaPaviaItaly
- IRCCS Mondino FoundationPaviaItaly
| | - Andrea Cortese
- Department of Brain and Behavioral SciencesUniversity of PaviaPaviaItaly
- Department of Neuromuscular DiseasesUCL Queen Square Institute of NeurologyLondonUnited Kingdom
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Seki S, Kitaoka Y, Kawata S, Nishiura A, Uchihashi T, Hiraoka SI, Yokota Y, Isomura ET, Kogo M, Tanaka S. Characteristics of Sensory Neuron Dysfunction in Amyotrophic Lateral Sclerosis (ALS): Potential for ALS Therapy. Biomedicines 2023; 11:2967. [PMID: 38001967 PMCID: PMC10669304 DOI: 10.3390/biomedicines11112967] [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: 09/07/2023] [Revised: 10/24/2023] [Accepted: 10/29/2023] [Indexed: 11/26/2023] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disorder characterised by the progressive degeneration of motor neurons, resulting in muscle weakness, paralysis, and, ultimately, death. Presently, no effective treatment for ALS has been established. Although motor neuron dysfunction is a hallmark of ALS, emerging evidence suggests that sensory neurons are also involved in the disease. In clinical research, 30% of patients with ALS had sensory symptoms and abnormal sensory nerve conduction studies in the lower extremities. Peroneal nerve biopsies show histological abnormalities in 90% of the patients. Preclinical research has reported several genetic abnormalities in the sensory neurons of animal models of ALS, as well as in motor neurons. Furthermore, the aggregation of misfolded proteins like TAR DNA-binding protein 43 has been reported in sensory neurons. This review aims to provide a comprehensive description of ALS-related sensory neuron dysfunction, focusing on its clinical changes and underlying mechanisms. Sensory neuron abnormalities in ALS are not limited to somatosensory issues; proprioceptive sensory neurons, such as MesV and DRG neurons, have been reported to form networks with motor neurons and may be involved in motor control. Despite receiving limited attention, sensory neuron abnormalities in ALS hold potential for new therapies targeting proprioceptive sensory neurons.
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Affiliation(s)
- Soju Seki
- Department of Oral and Maxillofacial Surgery, Graduate School of Dentistry, Osaka University, 1-8 Yamadaoka, Suita 565-0871, Osaka, Japan
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6
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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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7
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Sensory Involvement in Amyotrophic Lateral Sclerosis. Int J Mol Sci 2022; 23:ijms232415521. [PMID: 36555161 PMCID: PMC9779879 DOI: 10.3390/ijms232415521] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Revised: 11/19/2022] [Accepted: 12/03/2022] [Indexed: 12/13/2022] Open
Abstract
Although amyotrophic lateral sclerosis (ALS) is pre-eminently a motor disease, the existence of non-motor manifestations, including sensory involvement, has been described in the last few years. Although from a clinical perspective, sensory symptoms are overshadowed by their motor manifestations, this does not mean that their pathological significance is not relevant. In this review, we have made an extensive description of the involvement of sensory and autonomic systems described to date in ALS, from clinical, neurophysiological, neuroimaging, neuropathological, functional, and molecular perspectives.
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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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