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Gaudio A, Gotta F, Ponti C, Sanguineri F, Trevisan L, Geroldi A, Patrone S, Gemelli C, Cabona C, Astrea G, Fiorillo C, Gustincich S, Grandis M, Mandich P. Case report: Episodic ataxia without ataxia? Front Neurol 2023; 14:1224241. [PMID: 37965175 PMCID: PMC10640972 DOI: 10.3389/fneur.2023.1224241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Accepted: 10/03/2023] [Indexed: 11/16/2023] Open
Abstract
Hereditary myopathies represent a clinically and genetically heterogeneous group of neuromuscular disorders, characterized by highly variable clinical presentations and frequently overlapping phenotypes with other neuromuscular disorders, likely influenced by genetic and environmental modifiers. Genetic testing is often challenging due to ambiguous clinical diagnosis. Here, we present the case of a family with clinical and Electromyography (EMG) features resembling a myotonia-like disorder in which Whole Exome Sequencing (WES) analysis revealed the co-segregation of two rare missense variants in UBR4 and HSPG2, genes previously associated with episodic ataxia 8 (EA8). A review of the literature highlighted a striking overlap between the clinical and the molecular features of our family and the previously described episodic ataxias (EAs), which raises concerns about the genotype-phenotype correlation, clinical variability, and the confounding overlap in these groups of disorders. This emphasizes the importance of thoroughly framing the patient's phenotype. The more clear-cut the diagnosis, the easier the identification of a genetic determinant, and the better the prognosis and the treatment of patients.
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Affiliation(s)
- Andrea Gaudio
- IRCCS Ospedale Policlinico San Martino—UOC Genetica Medica, Genova, Italy
| | - Fabio Gotta
- IRCCS Ospedale Policlinico San Martino—UOC Genetica Medica, Genova, Italy
| | - Clarissa Ponti
- IRCCS Ospedale Policlinico San Martino—UOC Genetica Medica, Genova, Italy
- Department of Neuroscience, Rehabilitation, Ophthalmology, Genetics and Maternal and Child Health, University of Genova, Genova, Italy
| | - Francesca Sanguineri
- IRCCS Ospedale Policlinico San Martino—UOC Genetica Medica, Genova, Italy
- Department of Neuroscience, Rehabilitation, Ophthalmology, Genetics and Maternal and Child Health, University of Genova, Genova, Italy
| | - Lucia Trevisan
- Department of Neuroscience, Rehabilitation, Ophthalmology, Genetics and Maternal and Child Health, University of Genova, Genova, Italy
- IRCCS Ospedale Policlinico San Martino—SS Centro Tumori Ereditari, Genova, Italy
| | - Alessandro Geroldi
- Department of Neuroscience, Rehabilitation, Ophthalmology, Genetics and Maternal and Child Health, University of Genova, Genova, Italy
| | - Serena Patrone
- Department of Neuroscience, Rehabilitation, Ophthalmology, Genetics and Maternal and Child Health, University of Genova, Genova, Italy
| | - Chiara Gemelli
- IRCCS-Ospedale Policlinico San Martino—UOC Clinica Neurologica, Genova, Italy
| | - Corrado Cabona
- IRCCS-Ospedale Policlinico San Martino—UOC Neurofisiopatologia, Genova, Italy
| | | | - Chiara Fiorillo
- Department of Neuroscience, Rehabilitation, Ophthalmology, Genetics and Maternal and Child Health, University of Genova, Genova, Italy
- IRCCS Istituto Giannina Gaslini—UOC Neuropsichiatria Infantile, Genova, Italy
| | - Stefano Gustincich
- Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia, Genova, Italy
| | - Marina Grandis
- Department of Neuroscience, Rehabilitation, Ophthalmology, Genetics and Maternal and Child Health, University of Genova, Genova, Italy
- IRCCS-Ospedale Policlinico San Martino—UOC Clinica Neurologica, Genova, Italy
| | - Paola Mandich
- IRCCS Ospedale Policlinico San Martino—UOC Genetica Medica, Genova, Italy
- Department of Neuroscience, Rehabilitation, Ophthalmology, Genetics and Maternal and Child Health, University of Genova, Genova, Italy
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Zhang W, Jasinarachchi M, Seiderer L, Szmulewicz DJ, Roberts LJ. The Electrophysiological Findings in Spinocerebellar Ataxia Type 6: Evidence From 24 Patients. J Clin Neurophysiol 2023; 40:86-90. [PMID: 34038931 DOI: 10.1097/wnp.0000000000000855] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
PURPOSE Peripheral neuropathy has been reported commonly in several spinocerebellar ataxia (SCA) types. To date, there is a lack of robust evidence for neuropathy or neuronopathy in SCA type 6 (SCA6). Here, we aim to evaluate the presence of neuropathy or neuronopathy in a cohort of SCA6 patients. METHODS Twenty-four individuals with genetically confirmed SCA6 underwent detailed neurophysiological assessment. This included nerve conduction studies, and in some, cutaneous silent periods, blink reflexes, tilt table tests, quantitative sudomotor axon reflex tests, and somatosensory (median and tibial) evoked potentials. RESULTS Mean age was 56.1 years (range, 22-94 years) at the time of testing. Four patients were presymptomatic of SCA6 at recruitment. The mean disease duration of symptomatic patients was 11.9 years (range, 1-40 years). Most patients (79.2%, 19/24) had no neurophysiological evidence of a peripheral neuropathy. One with impaired glucose tolerance had mild, large, and small fiber sensorimotor polyneuropathy. One elderly patient had length-dependent axonal sensorimotor polyneuropathy. Two had minor sensory abnormalities (one had type II diabetes and previous chemotherapy). One other had minor small fiber abnormalities. Ten patients (41.7%) had median neuropathies at the wrist. All somatosensory evoked potential (15/15), and most autonomic function tests (13/14) were normal. CONCLUSIONS A large proportion of subjects (79.2%) in our cohort had no evidence of large or small fiber neuropathy. This study does not support the presence of neuropathy or neuronopathy as a common finding in SCA6 and confirms the importance of considering comorbidities as the cause of neurophysiological abnormalities.
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Affiliation(s)
- WenWen Zhang
- Department of Neurology, Alfred Hospital, Melbourne, Australia
| | - Mahi Jasinarachchi
- Department of Neurology and Neurological Research, St. Vincent's Hospital Melbourne, Melbourne, Australia; and
| | - Linda Seiderer
- Department of Neurology and Neurological Research, St. Vincent's Hospital Melbourne, Melbourne, Australia; and
| | - David J Szmulewicz
- Balance Disorders and Ataxia Service, Royal Victorian Eye and Ear Hospital, Melbourne, Australia
| | - Leslie J Roberts
- Department of Neurology and Neurological Research, St. Vincent's Hospital Melbourne, Melbourne, Australia; and
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Erro R, Magrinelli F, Bhatia KP. Paroxysmal movement disorders: Paroxysmal dyskinesia and episodic ataxia. HANDBOOK OF CLINICAL NEUROLOGY 2023; 196:347-365. [PMID: 37620078 DOI: 10.1016/b978-0-323-98817-9.00033-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/26/2023]
Abstract
Paroxysmal movement disorders have traditionally been classified into paroxysmal dyskinesia (PxD), which consists in attacks of involuntary movements (mainly dystonia and/or chorea) without loss of consciousness, and episodic ataxia (EA), which features spells of cerebellar dysfunction with or without interictal neurological manifestations. In this chapter, PxD will be discussed first according to the trigger-based classification, thus reviewing clinical, genetic, and molecular features of paroxysmal kinesigenic dyskinesia, paroxysmal nonkinesigenic dyskinesia, and paroxysmal exercise-induced dyskinesia. EA will be presented thereafter according to their designated gene or genetic locus. Clinicogenetic similarities among paroxysmal movement disorders have progressively emerged, which are herein highlighted along with growing evidence that their pathomechanisms overlap those of epilepsy and migraine. Advances in our comprehension of the biological pathways underlying paroxysmal movement disorders, which involve ion channels as well as proteins associated with the vesical synaptic cycle or implicated in neuronal energy metabolism, may represent the cornerstone for defining a shared pathophysiologic framework and developing target-specific therapies.
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Affiliation(s)
- Roberto Erro
- Department of Medicine, Surgery and Dentistry "Scuola Medica Salernitana", Neuroscience Section, University of Salerno, Baronissi, Salerno, Italy
| | - Francesca Magrinelli
- Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, University College London, London, United Kingdom
| | - Kailash P Bhatia
- Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, University College London, London, United Kingdom.
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Garrido Sanabria ER, Zahid A, Britton J, Kraus GJ, López-Chiriboga AS, Zekeridou A, Flanagan EP, McKeon A, Mills JR, Pittock SJ, Dubey D. CASPR2-IgG-associated autoimmune seizures. Epilepsia 2022; 63:709-722. [PMID: 35032032 DOI: 10.1111/epi.17164] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 12/26/2021] [Accepted: 12/28/2021] [Indexed: 12/31/2022]
Abstract
OBJECTIVE This study was undertaken to report clinical presentations and outcomes of CASPR2-IgG-associated seizures. METHODS Mayo Clinic Neuroimmunology database was queried to identify CASPR2-IgG-seropositive (CASPR2-IgG+) patients evaluated at our institution (2009-2019). RESULTS Of the 53 CASPR2-IgG+ patients (titer ≥ 1:10), 20 had seizures (38%). All seizure patients were male, with median onset age of 68 years. Eighteen (90%) had seizures at initial presentation. One patient was found to have malignancy (colon adenocarcinoma). Two patients had coexisting LGI1-IgG. Twelve patients had archived sera, which on titration had CASPR2-IgG titers ≥ 1:100. Fifteen patients (75%) met criteria for autoimmune encephalitis. Patients most commonly presented with focal onset, nonmotor seizures with impaired awareness (n = 14, 70%). Eleven patients also had focal motor and/or sensory seizures as one of the seizure semiologies. The majority of patients (n = 11, 55%) developed generalized tonic-clonic seizures during their disease course. Seizure clusters occurred in 12 patients. In addition to seizures, patients developed cognitive disturbance (n = 16, 80%), episodic emotional lability (n = 13, 65%), paroxysmal dizziness (n = 9, 45%), episodic ataxia (n = 6, 30%), and chronic ataxia (n = 9, 45%). Only three patients (15%) had coexisting peripheral nervous system involvement. Frontotemporal or temporal ictal and/or interictal electroencephalographic abnormalities were present among nine patients, and three had multifocal epileptiform abnormalities. Eight patients (40%) had medial temporal T2/fluid-attenuated inversion recovery hyperintensity on brain magnetic resonance imaging. Elevated cerebrospinal fluid protein and/or lymphocytic pleocytosis was present in most cases (13/14, 93%). Thirteen patients reached seizure freedom following initiation of antiseizure medication (ASM; n = 4) or a combination of immunotherapy and ASM (n = 9). Median duration of follow-up was 25 months (range = 2-136 months). SIGNIFICANCE CASPR2-IgG evaluation should be considered among older male patients with new onset focal seizures and impaired awareness often occurring in clusters with/without features of encephalitis. Coexisting neurological manifestations, including episodic emotional lability, ataxia, and paroxysmal dizziness, also aid in the diagnosis.
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Affiliation(s)
| | - Anza Zahid
- Department of Neurology, Mayo Clinic, Rochester, Minnesota, USA
| | - Jeffrey Britton
- Department of Neurology, Mayo Clinic, Rochester, Minnesota, USA
| | - Gregory J Kraus
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota, USA
| | | | - Anastasia Zekeridou
- Department of Neurology, Mayo Clinic, Rochester, Minnesota, USA.,Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota, USA
| | - Eoin P Flanagan
- Department of Neurology, Mayo Clinic, Rochester, Minnesota, USA.,Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota, USA
| | - Andrew McKeon
- Department of Neurology, Mayo Clinic, Rochester, Minnesota, USA.,Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota, USA
| | - John R Mills
- Department of Neurology, Mayo Clinic, Rochester, Minnesota, USA.,Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota, USA
| | - Sean J Pittock
- Department of Neurology, Mayo Clinic, Rochester, Minnesota, USA.,Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota, USA
| | - Divyanshu Dubey
- Department of Neurology, Mayo Clinic, Rochester, Minnesota, USA.,Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota, USA
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Roy PK, Rajesh Y, Mandal M. Therapeutic targeting of membrane-associated proteins in central nervous system tumors. Exp Cell Res 2021; 406:112760. [PMID: 34339674 DOI: 10.1016/j.yexcr.2021.112760] [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: 04/30/2021] [Revised: 06/28/2021] [Accepted: 07/28/2021] [Indexed: 12/09/2022]
Abstract
The activity of the most complex system, the central nervous system (CNS) is profoundly regulated by a huge number of membrane-associated proteins (MAP). A minor change stimulates immense chemical changes and the elicited response is organized by MAP, which acts as a receptor of that chemical or channel enabling the flow of ions. Slight changes in the activity or expression of these MAPs lead to severe consequences such as cognitive disorders, memory loss, or cancer. CNS tumors are heterogeneous in nature and hard-to-treat due to random mutations in MAPs; like as overexpression of EGFRvIII/TGFβR/VEGFR, change in adhesion molecules α5β3 integrin/SEMA3A, imbalance in ion channel proteins, etc. Extensive research is under process for developing new therapeutic approaches using these proteins such as targeted cytotoxic radiotherapy, drug-delivery, and prodrug activation, blocking of receptors like GluA1, developing viral vector against cell surface receptor. The combinatorial approach of these strategies along with the conventional one might be more potential. Henceforth, our review focuses on in-depth analysis regarding MAPs aiming for a better understanding for developing an efficient therapeutic approach for targeting CNS tumors.
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Affiliation(s)
- Pritam Kumar Roy
- School of Medical Science and Technology, Indian Institute of Technology Kharagpur, India
| | - Yetirajam Rajesh
- Department of Human and Molecular Genetics, School of Medicine, Virginia Commonwealth University, Richmond, VA, USA
| | - Mahitosh Mandal
- School of Medical Science and Technology, Indian Institute of Technology Kharagpur, India.
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Koźmiński W, Pera J. Involvement of the Peripheral Nervous System in Episodic Ataxias. Biomedicines 2020; 8:biomedicines8110448. [PMID: 33105744 PMCID: PMC7690566 DOI: 10.3390/biomedicines8110448] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 10/20/2020] [Accepted: 10/21/2020] [Indexed: 12/04/2022] Open
Abstract
Episodic ataxias comprise a group of inherited disorders, which have a common hallmark—transient attacks of ataxia. The genetic background is heterogeneous and the causative genes are not always identified. Furthermore, the clinical presentation, including intraictal and interictal symptoms, as well as the retention and progression of neurological deficits, is heterogeneous. Spells of ataxia can be accompanied by other symptoms—mostly from the central nervous system. However, in some of episodic ataxias involvement of peripheral nervous system is a part of typical clinical picture. This review intends to provide an insight into involvement of peripheral nervous system in episodic ataxias.
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Affiliation(s)
- Wojciech Koźmiński
- Department of Neurology, University Hospital, ul. Jakubowskiego 2, 30-688 Krakow, Poland;
| | - Joanna Pera
- Department of Neurology, Jagiellonian University Medical College, ul. Botaniczna 3, 31-503 Krakow, Poland
- Correspondence:
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Clinical and Genetic Overview of Paroxysmal Movement Disorders and Episodic Ataxias. Int J Mol Sci 2020; 21:ijms21103603. [PMID: 32443735 PMCID: PMC7279391 DOI: 10.3390/ijms21103603] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Revised: 05/11/2020] [Accepted: 05/13/2020] [Indexed: 12/15/2022] Open
Abstract
Paroxysmal movement disorders (PMDs) are rare neurological diseases typically manifesting with intermittent attacks of abnormal involuntary movements. Two main categories of PMDs are recognized based on the phenomenology: Paroxysmal dyskinesias (PxDs) are characterized by transient episodes hyperkinetic movement disorders, while attacks of cerebellar dysfunction are the hallmark of episodic ataxias (EAs). From an etiological point of view, both primary (genetic) and secondary (acquired) causes of PMDs are known. Recognition and diagnosis of PMDs is based on personal and familial medical history, physical examination, detailed reconstruction of ictal phenomenology, neuroimaging, and genetic analysis. Neurophysiological or laboratory tests are reserved for selected cases. Genetic knowledge of PMDs has been largely incremented by the advent of next generation sequencing (NGS) methodologies. The wide number of genes involved in the pathogenesis of PMDs reflects a high complexity of molecular bases of neurotransmission in cerebellar and basal ganglia circuits. In consideration of the broad genetic and phenotypic heterogeneity, a NGS approach by targeted panel for movement disorders, clinical or whole exome sequencing should be preferred, whenever possible, to a single gene approach, in order to increase diagnostic rate. This review is focused on clinical and genetic features of PMDs with the aim to (1) help clinicians to recognize, diagnose and treat patients with PMDs as well as to (2) provide an overview of genes and molecular mechanisms underlying these intriguing neurogenetic disorders.
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8
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Pilotto F, Saxena S. Epidemiology of inherited cerebellar ataxias and challenges in clinical research. CLINICAL AND TRANSLATIONAL NEUROSCIENCE 2018. [DOI: 10.1177/2514183x18785258] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Federica Pilotto
- Department of Neurology, Inselspital University Hospital, University of Bern, Bern, Switzerland
- Department for BioMedical Research, University of Bern, Bern, Switzerland
- Regenerative Neuroscience Cluster, University of Bern, Bern, Switzerland
| | - Smita Saxena
- Department of Neurology, Inselspital University Hospital, University of Bern, Bern, Switzerland
- Department for BioMedical Research, University of Bern, Bern, Switzerland
- Regenerative Neuroscience Cluster, University of Bern, Bern, Switzerland
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9
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Abstract
Episodic ataxia (EA) is a rare neurological condition characterized by recurrent spells of truncal ataxia and incoordination. Five genes (KCNA1, CACNA1A, CACNB4, SLC1A3, and UBR4) have been linked to EA. Despite extensive efforts to genetically diagnose EA, many patients remain still undiagnosed. Whole-exome sequencing was carried out in 39 Korean patients with EA to identify pathogenic mutations of the five known EA genes. We also evaluated 40 candidate genes that cause EA as a secondary phenotype or cerebellar ataxia. Eighteen patients (46%) revealed genetic information useful for establishing a molecular diagnosis of EA. In 11 patients, 16 pathogenic mutations were detected in three EA genes. These included nine mutations in CACNA1A, three in SLC1A3, and four in UBR4. Three patients had mutations in two genes, either CACNA1A and SLC1A3 or CACNA1A and UBR4, suggesting that SLC1A3 and UBR4 may act as genetic modifiers with synergic effects on the abnormal presynaptic activity caused by CACNA1A mutations. In seven patients with negative results for screening of EA genes, potential pathogenic mutations were identified in the candidate genes ATP1A2, SCN1A, TTBK2, TGM6, FGF14, and KCND3. This study demonstrates the genetic heterogeneity of Korean EA, and indicates that whole-exome sequencing may be useful for molecular genetic diagnosis of EA.
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10
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Joubert B, Gobert F, Thomas L, Saint-Martin M, Desestret V, Convers P, Rogemond V, Picard G, Ducray F, Psimaras D, Antoine JC, Delattre JY, Honnorat J. Autoimmune episodic ataxia in patients with anti-CASPR2 antibody-associated encephalitis. NEUROLOGY-NEUROIMMUNOLOGY & NEUROINFLAMMATION 2017. [PMID: 28638854 PMCID: PMC5471489 DOI: 10.1212/nxi.0000000000000371] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Objective: To report paroxysmal episodes of cerebellar ataxia in a patient with anti–contactin-associated protein-like 2 (CASPR2) antibody-related autoimmune encephalitis and to search for similar paroxysmal ataxia in a cohort of patients with anti–CASPR2 antibody-associated autoimmune encephalitis. Methods: We report a patient with paroxysmal episodes of cerebellar ataxia observed during autoimmune encephalitis with anti-CASPR2 antibodies. In addition, clinical analysis was performed in a retrospective cohort of 37 patients with anti-CASPR2 antibodies to search for transient episodes of ataxia. Paroxysmal symptoms were further specified from the referral physicians, the patients, or their relatives. Results: A 61-year-old man with limbic encephalitis and anti-CASPR2 antibodies developed stereotyped paroxysmal episodes of cerebellar ataxia, including gait imbalance, dysarthria, and dysmetria, 1 month after the onset of the encephalitis. The ataxic episodes were specifically triggered by orthostatism and emotions. Both limbic symptoms and transient ataxic episodes resolved after treatment with steroids and IV cyclophosphamide. Among 37 other patients with anti-CASPR2 antibodies, we identified 5 additional cases with similar paroxysmal ataxic episodes that included gait imbalance (5 cases), slurred speech (3 cases), limb dysmetria (3 cases), and nystagmus (1 case). All had concomitant limbic encephalitis. Paroxysmal ataxia was not observed in patients with neuromyotonia or Morvan syndrome. Triggering factors (orthostatism or anger) were reported in 4 patients. Episodes resolved with immunomodulatory treatments in 4 patients and spontaneously in 1 case. Conclusions: Paroxysmal cerebellar ataxia must be added to the spectrum of the anti-CASPR2 antibody syndrome.
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Affiliation(s)
- Bastien Joubert
- Centre National de Référence pour les Syndromes Neurologiques Paranéoplasiques (B.J., L.T., V.D., V.R., G.P., F.D., D.P., J.-C.A., J.-Y.D., J.H.), Service de Neuro-Réanimation (F.G.), Hôpital Neurologique, Hospices Civils de Lyon, Bron; Institut NeuroMyoGene INSERM U1217/CNRS UMR 5310 (B.J., F.G., L.T., M.S.-M., V.D., V.R., G.P., F.D., J.H.), University of Lyon-Université Claude Bernard Lyon 1; Service de Neurologie (P.C., J.-C.A.), Hôpital Bellevue, Centre Hospitalier Universitaire de Saint-Étienne; and Département de Neurologie (D.P., J.-Y.D.), Groupe Hospitalier Pitié-Salpêtrière, Assistance Publique-Hôpitaux de Paris, France
| | - Florent Gobert
- Centre National de Référence pour les Syndromes Neurologiques Paranéoplasiques (B.J., L.T., V.D., V.R., G.P., F.D., D.P., J.-C.A., J.-Y.D., J.H.), Service de Neuro-Réanimation (F.G.), Hôpital Neurologique, Hospices Civils de Lyon, Bron; Institut NeuroMyoGene INSERM U1217/CNRS UMR 5310 (B.J., F.G., L.T., M.S.-M., V.D., V.R., G.P., F.D., J.H.), University of Lyon-Université Claude Bernard Lyon 1; Service de Neurologie (P.C., J.-C.A.), Hôpital Bellevue, Centre Hospitalier Universitaire de Saint-Étienne; and Département de Neurologie (D.P., J.-Y.D.), Groupe Hospitalier Pitié-Salpêtrière, Assistance Publique-Hôpitaux de Paris, France
| | - Laure Thomas
- Centre National de Référence pour les Syndromes Neurologiques Paranéoplasiques (B.J., L.T., V.D., V.R., G.P., F.D., D.P., J.-C.A., J.-Y.D., J.H.), Service de Neuro-Réanimation (F.G.), Hôpital Neurologique, Hospices Civils de Lyon, Bron; Institut NeuroMyoGene INSERM U1217/CNRS UMR 5310 (B.J., F.G., L.T., M.S.-M., V.D., V.R., G.P., F.D., J.H.), University of Lyon-Université Claude Bernard Lyon 1; Service de Neurologie (P.C., J.-C.A.), Hôpital Bellevue, Centre Hospitalier Universitaire de Saint-Étienne; and Département de Neurologie (D.P., J.-Y.D.), Groupe Hospitalier Pitié-Salpêtrière, Assistance Publique-Hôpitaux de Paris, France
| | - Margaux Saint-Martin
- Centre National de Référence pour les Syndromes Neurologiques Paranéoplasiques (B.J., L.T., V.D., V.R., G.P., F.D., D.P., J.-C.A., J.-Y.D., J.H.), Service de Neuro-Réanimation (F.G.), Hôpital Neurologique, Hospices Civils de Lyon, Bron; Institut NeuroMyoGene INSERM U1217/CNRS UMR 5310 (B.J., F.G., L.T., M.S.-M., V.D., V.R., G.P., F.D., J.H.), University of Lyon-Université Claude Bernard Lyon 1; Service de Neurologie (P.C., J.-C.A.), Hôpital Bellevue, Centre Hospitalier Universitaire de Saint-Étienne; and Département de Neurologie (D.P., J.-Y.D.), Groupe Hospitalier Pitié-Salpêtrière, Assistance Publique-Hôpitaux de Paris, France
| | - Virginie Desestret
- Centre National de Référence pour les Syndromes Neurologiques Paranéoplasiques (B.J., L.T., V.D., V.R., G.P., F.D., D.P., J.-C.A., J.-Y.D., J.H.), Service de Neuro-Réanimation (F.G.), Hôpital Neurologique, Hospices Civils de Lyon, Bron; Institut NeuroMyoGene INSERM U1217/CNRS UMR 5310 (B.J., F.G., L.T., M.S.-M., V.D., V.R., G.P., F.D., J.H.), University of Lyon-Université Claude Bernard Lyon 1; Service de Neurologie (P.C., J.-C.A.), Hôpital Bellevue, Centre Hospitalier Universitaire de Saint-Étienne; and Département de Neurologie (D.P., J.-Y.D.), Groupe Hospitalier Pitié-Salpêtrière, Assistance Publique-Hôpitaux de Paris, France
| | - Philippe Convers
- Centre National de Référence pour les Syndromes Neurologiques Paranéoplasiques (B.J., L.T., V.D., V.R., G.P., F.D., D.P., J.-C.A., J.-Y.D., J.H.), Service de Neuro-Réanimation (F.G.), Hôpital Neurologique, Hospices Civils de Lyon, Bron; Institut NeuroMyoGene INSERM U1217/CNRS UMR 5310 (B.J., F.G., L.T., M.S.-M., V.D., V.R., G.P., F.D., J.H.), University of Lyon-Université Claude Bernard Lyon 1; Service de Neurologie (P.C., J.-C.A.), Hôpital Bellevue, Centre Hospitalier Universitaire de Saint-Étienne; and Département de Neurologie (D.P., J.-Y.D.), Groupe Hospitalier Pitié-Salpêtrière, Assistance Publique-Hôpitaux de Paris, France
| | - Véronique Rogemond
- Centre National de Référence pour les Syndromes Neurologiques Paranéoplasiques (B.J., L.T., V.D., V.R., G.P., F.D., D.P., J.-C.A., J.-Y.D., J.H.), Service de Neuro-Réanimation (F.G.), Hôpital Neurologique, Hospices Civils de Lyon, Bron; Institut NeuroMyoGene INSERM U1217/CNRS UMR 5310 (B.J., F.G., L.T., M.S.-M., V.D., V.R., G.P., F.D., J.H.), University of Lyon-Université Claude Bernard Lyon 1; Service de Neurologie (P.C., J.-C.A.), Hôpital Bellevue, Centre Hospitalier Universitaire de Saint-Étienne; and Département de Neurologie (D.P., J.-Y.D.), Groupe Hospitalier Pitié-Salpêtrière, Assistance Publique-Hôpitaux de Paris, France
| | - Géraldine Picard
- Centre National de Référence pour les Syndromes Neurologiques Paranéoplasiques (B.J., L.T., V.D., V.R., G.P., F.D., D.P., J.-C.A., J.-Y.D., J.H.), Service de Neuro-Réanimation (F.G.), Hôpital Neurologique, Hospices Civils de Lyon, Bron; Institut NeuroMyoGene INSERM U1217/CNRS UMR 5310 (B.J., F.G., L.T., M.S.-M., V.D., V.R., G.P., F.D., J.H.), University of Lyon-Université Claude Bernard Lyon 1; Service de Neurologie (P.C., J.-C.A.), Hôpital Bellevue, Centre Hospitalier Universitaire de Saint-Étienne; and Département de Neurologie (D.P., J.-Y.D.), Groupe Hospitalier Pitié-Salpêtrière, Assistance Publique-Hôpitaux de Paris, France
| | - François Ducray
- Centre National de Référence pour les Syndromes Neurologiques Paranéoplasiques (B.J., L.T., V.D., V.R., G.P., F.D., D.P., J.-C.A., J.-Y.D., J.H.), Service de Neuro-Réanimation (F.G.), Hôpital Neurologique, Hospices Civils de Lyon, Bron; Institut NeuroMyoGene INSERM U1217/CNRS UMR 5310 (B.J., F.G., L.T., M.S.-M., V.D., V.R., G.P., F.D., J.H.), University of Lyon-Université Claude Bernard Lyon 1; Service de Neurologie (P.C., J.-C.A.), Hôpital Bellevue, Centre Hospitalier Universitaire de Saint-Étienne; and Département de Neurologie (D.P., J.-Y.D.), Groupe Hospitalier Pitié-Salpêtrière, Assistance Publique-Hôpitaux de Paris, France
| | - Dimitri Psimaras
- Centre National de Référence pour les Syndromes Neurologiques Paranéoplasiques (B.J., L.T., V.D., V.R., G.P., F.D., D.P., J.-C.A., J.-Y.D., J.H.), Service de Neuro-Réanimation (F.G.), Hôpital Neurologique, Hospices Civils de Lyon, Bron; Institut NeuroMyoGene INSERM U1217/CNRS UMR 5310 (B.J., F.G., L.T., M.S.-M., V.D., V.R., G.P., F.D., J.H.), University of Lyon-Université Claude Bernard Lyon 1; Service de Neurologie (P.C., J.-C.A.), Hôpital Bellevue, Centre Hospitalier Universitaire de Saint-Étienne; and Département de Neurologie (D.P., J.-Y.D.), Groupe Hospitalier Pitié-Salpêtrière, Assistance Publique-Hôpitaux de Paris, France
| | - Jean-Christophe Antoine
- Centre National de Référence pour les Syndromes Neurologiques Paranéoplasiques (B.J., L.T., V.D., V.R., G.P., F.D., D.P., J.-C.A., J.-Y.D., J.H.), Service de Neuro-Réanimation (F.G.), Hôpital Neurologique, Hospices Civils de Lyon, Bron; Institut NeuroMyoGene INSERM U1217/CNRS UMR 5310 (B.J., F.G., L.T., M.S.-M., V.D., V.R., G.P., F.D., J.H.), University of Lyon-Université Claude Bernard Lyon 1; Service de Neurologie (P.C., J.-C.A.), Hôpital Bellevue, Centre Hospitalier Universitaire de Saint-Étienne; and Département de Neurologie (D.P., J.-Y.D.), Groupe Hospitalier Pitié-Salpêtrière, Assistance Publique-Hôpitaux de Paris, France
| | - Jean-Yves Delattre
- Centre National de Référence pour les Syndromes Neurologiques Paranéoplasiques (B.J., L.T., V.D., V.R., G.P., F.D., D.P., J.-C.A., J.-Y.D., J.H.), Service de Neuro-Réanimation (F.G.), Hôpital Neurologique, Hospices Civils de Lyon, Bron; Institut NeuroMyoGene INSERM U1217/CNRS UMR 5310 (B.J., F.G., L.T., M.S.-M., V.D., V.R., G.P., F.D., J.H.), University of Lyon-Université Claude Bernard Lyon 1; Service de Neurologie (P.C., J.-C.A.), Hôpital Bellevue, Centre Hospitalier Universitaire de Saint-Étienne; and Département de Neurologie (D.P., J.-Y.D.), Groupe Hospitalier Pitié-Salpêtrière, Assistance Publique-Hôpitaux de Paris, France
| | - Jérôme Honnorat
- Centre National de Référence pour les Syndromes Neurologiques Paranéoplasiques (B.J., L.T., V.D., V.R., G.P., F.D., D.P., J.-C.A., J.-Y.D., J.H.), Service de Neuro-Réanimation (F.G.), Hôpital Neurologique, Hospices Civils de Lyon, Bron; Institut NeuroMyoGene INSERM U1217/CNRS UMR 5310 (B.J., F.G., L.T., M.S.-M., V.D., V.R., G.P., F.D., J.H.), University of Lyon-Université Claude Bernard Lyon 1; Service de Neurologie (P.C., J.-C.A.), Hôpital Bellevue, Centre Hospitalier Universitaire de Saint-Étienne; and Département de Neurologie (D.P., J.-Y.D.), Groupe Hospitalier Pitié-Salpêtrière, Assistance Publique-Hôpitaux de Paris, France
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11
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Tomlinson SE, Howells J, Burke D. In vivo assessment of neurological channelopathies: Application of peripheral nerve excitability studies. Neuropharmacology 2017; 132:98-107. [PMID: 28476643 DOI: 10.1016/j.neuropharm.2017.04.045] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Revised: 04/19/2017] [Accepted: 04/29/2017] [Indexed: 12/14/2022]
Abstract
With the rapid evolution of understanding of neurological channelopathies comes a need for sensitive tools to evaluate patients in clinical practice. Neurological channelopathies with a single-gene basis can manifest as seizures, headache, ataxia, vertigo, confusion, weakness and neuropathic pain and it is likely that other genetic factors contribute to the phenotype of many of these disorders. Ion channel dysfunction can result in abnormal cell membrane excitability but utilisation of advanced neurophysiology techniques has lagged behind developments in clinical, genetic and imaging evaluation of channelopathies. However, momentum in the application of in vivo axonal excitability testing sees these tests emerging as valuable tools, with the capacity to provide sensitive and specific insights into the mechanism of disease. While single-channel function cannot be directly measured in vivo, evaluation of subjects with single-gene channelopathies has provided insights into the effects of mutation-related alterations of membrane excitability, as well as compensatory adaptive changes. By showing how ion channel dysfunction can affect axonal excitability in vivo, studies of the excitability of peripheral nerve axons complement in vitro analysis of single channel activity. The interpretation of results is enhanced by mathematical modelling of axonal function and insights provided by in vitro work. This article is part of the Special Issue entitled 'Channelopathies.'
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Affiliation(s)
- Susan E Tomlinson
- Sydney Medical School, University of Sydney, Sydney, Australia; Department of Neurology, St Vincent's Hospital, Sydney, Australia.
| | - James Howells
- Brain and Mind Centre, University of Sydney, Sydney, Australia
| | - David Burke
- Sydney Medical School, University of Sydney, Sydney, Australia; Department of Neurology, Royal Prince Alfred Hospital, Sydney, Australia
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12
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Choi KD, Choi JH. Episodic Ataxias: Clinical and Genetic Features. J Mov Disord 2016; 9:129-35. [PMID: 27667184 PMCID: PMC5035943 DOI: 10.14802/jmd.16028] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Revised: 07/25/2016] [Accepted: 08/01/2016] [Indexed: 11/24/2022] Open
Abstract
Episodic ataxia (EA) is a clinically heterogeneous group of disorders that are characterized by recurrent spells of truncal ataxia and incoordination lasting minutes to hours. Most have an autosomal dominant inheritance pattern. To date, 8 subtypes have been defined according to clinical and genetic characteristics, and five genes are known to be linked to EAs. Both EA1 and EA2, which are caused by mutations in KCNA1 and CACNA1A, account for the majority of EA, but many patients with no identified mutations still exhibit EA-like clinical features. Furthermore, genetically confirmed EAs have mostly been identified in Caucasian families. In this article, we review the current knowledge on the clinical and genetic characteristics of EAs. Additionally, we summarize the phenotypic features of the genetically confirmed EA2 families in Korea.
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Affiliation(s)
- Kwang-Dong Choi
- Department of Neurology, College of Medicine, Pusan National University Hospital, Pusan National University School of Medicine and Biomedical Research Institute, Busan, Korea
| | - Jae-Hwan Choi
- Department of Neurology, Pusan National University School of Medicine, Research Institute for Convergence of Biomedical Science and Technology, Pusan National University Yangsan Hospital, Yangsan, Korea
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13
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Tomlinson SE, Tan SV, Burke D, Labrum RW, Haworth A, Gibbons VS, Sweeney MG, Griggs RC, Kullmann DM, Bostock H, Hanna MG. In vivo impact of presynaptic calcium channel dysfunction on motor axons in episodic ataxia type 2. Brain 2016; 139:380-91. [PMID: 26912519 PMCID: PMC4795516 DOI: 10.1093/brain/awv380] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Revised: 10/22/2015] [Accepted: 10/26/2015] [Indexed: 11/13/2022] Open
Abstract
Ion channel dysfunction causes a range of neurological disorders by altering transmembrane ion fluxes, neuronal or muscle excitability, and neurotransmitter release. Genetic neuronal channelopathies affecting peripheral axons provide a unique opportunity to examine the impact of dysfunction of a single channel subtype in detail in vivo. Episodic ataxia type 2 is caused by mutations in CACNA1A, which encodes the pore-forming subunit of the neuronal voltage-gated calcium channel Cav2.1. In peripheral motor axons, this channel is highly expressed at the presynaptic neuromuscular junction where it contributes to action potential-evoked neurotransmitter release, but it is not expressed mid-axon or thought to contribute to action potential generation. Eight patients from five families with genetically confirmed episodic ataxia type 2 underwent neurophysiological assessment to determine whether axonal excitability was normal and, if not, whether changes could be explained by Cav2.1 dysfunction. New mutations in the CACNA1A gene were identified in two families. Nerve conduction studies were normal, but increased jitter in single-fibre EMG studies indicated unstable neuromuscular transmission in two patients. Excitability properties of median motor axons were compared with those in 30 age-matched healthy control subjects. All patients had similar excitability abnormalities, including a high electrical threshold and increased responses to hyperpolarizing (P < 0.00007) and depolarizing currents (P < 0.001) in threshold electrotonus. In the recovery cycle, refractoriness (P < 0.0002) and superexcitability (P < 0.006) were increased. Cav2.1 dysfunction in episodic ataxia type 2 thus has unexpected effects on axon excitability, which may reflect an indirect effect of abnormal calcium current fluxes during development.
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Affiliation(s)
- Susan E Tomlinson
- 1 Sydney Medical School, University of Sydney, Australia 2 Department of Neurology, St Vincent's Hospital, Sydney, Australia
| | - S Veronica Tan
- 3 Institute of Neurology, University College London and MRC Centre for Neuromuscular Disease, Queen Square, UK
| | - David Burke
- 1 Sydney Medical School, University of Sydney, Australia 4 Department of Neurology, Royal Prince Alfred Hospital, Sydney, Australia
| | - Robyn W Labrum
- 5 Neurogenetics Unit, National Hospital for Neurology, Queen Square, UK
| | - Andrea Haworth
- 5 Neurogenetics Unit, National Hospital for Neurology, Queen Square, UK
| | | | - Mary G Sweeney
- 5 Neurogenetics Unit, National Hospital for Neurology, Queen Square, UK
| | | | - Dimitri M Kullmann
- 3 Institute of Neurology, University College London and MRC Centre for Neuromuscular Disease, Queen Square, UK 5 Neurogenetics Unit, National Hospital for Neurology, Queen Square, UK
| | - Hugh Bostock
- 3 Institute of Neurology, University College London and MRC Centre for Neuromuscular Disease, Queen Square, UK
| | - Michael G Hanna
- 3 Institute of Neurology, University College London and MRC Centre for Neuromuscular Disease, Queen Square, UK 5 Neurogenetics Unit, National Hospital for Neurology, Queen Square, UK
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14
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Chen SH, Fu SJ, Huang JJ, Tang CY. The episodic ataxia type 1 mutation I262T alters voltage-dependent gating and disrupts protein biosynthesis of human Kv1.1 potassium channels. Sci Rep 2016; 6:19378. [PMID: 26778656 PMCID: PMC4726062 DOI: 10.1038/srep19378] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Accepted: 12/07/2015] [Indexed: 01/08/2023] Open
Abstract
Voltage-gated potassium (Kv) channels are essential for setting neuronal membrane excitability. Mutations in human Kv1.1 channels are linked to episodic ataxia type 1 (EA1). The EA1-associated mutation I262T was identified from a patient with atypical phenotypes. Although a previous report has characterized its suppression effect, several key questions regarding the impact of the I262T mutation on Kv1.1 as well as other members of the Kv1 subfamily remain unanswered. Herein we show that the dominant-negative effect of I262T on Kv1.1 current expression is not reversed by co-expression with Kvβ1.1 or Kvβ2 subunits. Biochemical examinations indicate that I262T displays enhanced protein degradation and impedes membrane trafficking of Kv1.1 wild-type subunits. I262T appears to be the first EA1 mutation directly associated with impaired protein stability. Further functional analyses demonstrate that I262T changes the voltage-dependent activation and Kvβ1.1-mediated inactivation, uncouples inactivation from activation gating, and decelerates the kinetics of cumulative inactivation of Kv1.1 channels. I262T also exerts similar dominant effects on the gating of Kv1.2 and Kv1.4 channels. Together our data suggest that I262T confers altered channel gating and reduced functional expression of Kv1 channels, which may account for some of the phenotypes of the EA1 patient.
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Affiliation(s)
- Szu-Han Chen
- Department of Physiology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Ssu-Ju Fu
- Department of Physiology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Jing-Jia Huang
- Department of Physiology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Chih-Yung Tang
- Department of Physiology, College of Medicine, National Taiwan University, Taipei, Taiwan.,Graduate Institute of Brain and Mind Sciences, College of Medicine, National Taiwan University, Taipei, Taiwan
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15
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Spillane J, Kullmann DM, Hanna MG. Genetic neurological channelopathies: molecular genetics and clinical phenotypes. J Neurol Neurosurg Psychiatry 2016; 87:37-48. [PMID: 26558925 PMCID: PMC4717447 DOI: 10.1136/jnnp-2015-311233] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Accepted: 09/13/2015] [Indexed: 01/08/2023]
Abstract
Evidence accumulated over recent years has shown that genetic neurological channelopathies can cause many different neurological diseases. Presentations relating to the brain, spinal cord, peripheral nerve or muscle mean that channelopathies can impact on almost any area of neurological practice. Typically, neurological channelopathies are inherited in an autosomal dominant fashion and cause paroxysmal disturbances of neurological function, although the impairment of function can become fixed with time. These disorders are individually rare, but an accurate diagnosis is important as it has genetic counselling and often treatment implications. Furthermore, the study of less common ion channel mutation-related diseases has increased our understanding of pathomechanisms that is relevant to common neurological diseases such as migraine and epilepsy. Here, we review the molecular genetic and clinical features of inherited neurological channelopathies.
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Affiliation(s)
- J Spillane
- Royal Free Hospital Foundation Trust London, London, UK MRC Centre for Neuromuscular Disease, UCL, London, UK
| | - D M Kullmann
- MRC Centre for Neuromuscular Disease, UCL, London, UK UCL, Institute of Neurology, London, UK
| | - M G Hanna
- MRC Centre for Neuromuscular Disease, UCL, London, UK UCL, Institute of Neurology, London, UK
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16
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Profiling neuronal ion channelopathies with non-invasive brain imaging and dynamic causal models: Case studies of single gene mutations. Neuroimage 2015; 124:43-53. [PMID: 26342528 PMCID: PMC4655917 DOI: 10.1016/j.neuroimage.2015.08.057] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Revised: 07/31/2015] [Accepted: 08/25/2015] [Indexed: 11/24/2022] Open
Abstract
Clinical assessments of brain function rely upon visual inspection of electroencephalographic waveform abnormalities in tandem with functional magnetic resonance imaging. However, no current technology proffers in vivo assessments of activity at synapses, receptors and ion-channels, the basis of neuronal communication. Using dynamic causal modeling we compared electrophysiological responses from two patients with distinct monogenic ion channelopathies and a large cohort of healthy controls to demonstrate the feasibility of assaying synaptic-level channel communication non-invasively. Synaptic channel abnormality was identified in both patients (100% sensitivity) with assay specificity above 89%, furnishing estimates of neurotransmitter and voltage-gated ion throughput of sodium, calcium, chloride and potassium. This performance indicates a potential novel application as an adjunct for clinical assessments in neurological and psychiatric settings. More broadly, these findings indicate that biophysical models of synaptic channels can be estimated non-invasively, having important implications for advancing human neuroimaging to the level of non-invasive ion channel assays. Dynamic causal modeling (DCM) for M/EEG includes ion channel parameter estimates. Parameter estimates from patients with monogenic ion channelopathies were compared. Synaptic channel abnormality was identified in patients, with specificity above 89%. DCM could serve as a platform for non-invasively assaying brain molecular dynamics.
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Rose SJ, Kriener LH, Heinzer AK, Fan X, Raike RS, van den Maagdenberg AMJM, Hess EJ. The first knockin mouse model of episodic ataxia type 2. Exp Neurol 2014; 261:553-62. [PMID: 25109669 DOI: 10.1016/j.expneurol.2014.08.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Revised: 07/07/2014] [Accepted: 08/01/2014] [Indexed: 12/28/2022]
Abstract
Episodic ataxia type 2 (EA2) is an autosomal dominant disorder associated with attacks of ataxia that are typically precipitated by stress, ethanol, caffeine or exercise. EA2 is caused by loss-of-function mutations in the CACNA1A gene, which encodes the α1A subunit of the CaV2.1 voltage-gated Ca(2+) channel. To better understand the pathomechanisms of this disorder in vivo, we created the first genetic animal model of EA2 by engineering a mouse line carrying the EA2-causing c.4486T>G (p.F1406C) missense mutation in the orthologous mouse Cacna1a gene. Mice homozygous for the mutated allele exhibit a ~70% reduction in CaV2.1 current density in Purkinje cells, though surprisingly do not exhibit an overt motor phenotype. Mice hemizygous for the knockin allele (EA2/- mice) did exhibit motor dysfunction measurable by rotarod and pole test. Studies using Cre-flox conditional genetics explored the role of cerebellar Purkinje cells or cerebellar granule cells in the poor motor performance of EA2/- mice and demonstrate that manipulation of either cell type alone did not cause poor motor performance. Thus, it is possible that subtle dysfunction arising from multiple cell types is necessary for the expression of certain ataxia syndromes.
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Affiliation(s)
- Samuel J Rose
- Department of Pharmacology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Lisa H Kriener
- Department of Pharmacology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Ann K Heinzer
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| | - Xueliang Fan
- Department of Pharmacology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Robert S Raike
- Department of Pharmacology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Arn M J M van den Maagdenberg
- Department of Human Genetics, Leiden University Medical Centre, 2300 RC Leiden, The Netherlands; Department of Neurology, Leiden University Medical Centre, 2300 RC Leiden, The Netherlands
| | - Ellen J Hess
- Department of Pharmacology, Emory University School of Medicine, Atlanta, GA 30322, USA; Department of Neurology, Emory University School of Medicine, Atlanta, GA 30322, USA.
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18
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Tomlinson SE, Rajakulendran S, Tan SV, Graves TD, Bamiou DE, Labrum RW, Burke D, Sue CM, Giunti P, Schorge S, Kullmann DM, Hanna MG. Clinical, genetic, neurophysiological and functional study of new mutations in episodic ataxia type 1. J Neurol Neurosurg Psychiatry 2013; 84:1107-12. [PMID: 23349320 PMCID: PMC4332158 DOI: 10.1136/jnnp-2012-304131] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
BACKGROUND AND OBJECTIVE Heterozygous mutations in KCNA1 cause episodic ataxia type 1 (EA1), an ion channel disorder characterised by brief paroxysms of cerebellar dysfunction and persistent neuromyotonia. This paper describes four previously unreported families with EA1, with the aim of understanding the phenotypic spectrum associated with different mutations. METHODS 15 affected individuals from four families underwent clinical, genetic and neurophysiological evaluation. The functional impact of new mutations identified in the KCNA1 gene was investigated with in vitro electrophysiology and immunocytochemistry. RESULTS Detailed clinical documentation, dating back to 1928 in one family, indicates that all patients manifested episodic ataxia of varying severity. Four subjects from three families reported hearing impairment, which has not previously been reported in association with EA1. New mutations (R167M, C185W and I407M) were identified in three out of the four families. When expressed in human embryonic kidney cells, all three new mutations resulted in a loss of K(v)1.1 channel function. The fourth family harboured a previously reported A242P mutation, which has not been previously described in association with ataxia. CONCLUSIONS The genetic basis of EA1 in four families is established and this report presents the earliest documented case from 1928. All three new mutations caused a loss of K(v)1.1 channel function. The finding of deafness in four individuals raises the possibility of a link between K(v)1.1 dysfunction and hearing impairment. Our findings broaden the phenotypic range associated with mutations in KCNA1.
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19
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Kipfer S, Jung S, Lemke JR, Kipfer-Kauer A, Howell JP, Kaelin-Lang A, Nyffeler T, Gutbrod K, Abicht A, Müri RM. Novel CACNA1A mutation(s) associated with slow saccade velocities. J Neurol 2013; 260:3010-4. [DOI: 10.1007/s00415-013-7099-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2013] [Revised: 08/23/2013] [Accepted: 09/06/2013] [Indexed: 01/11/2023]
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20
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Waszkielewicz AM, Gunia A, Szkaradek N, Słoczyńska K, Krupińska S, Marona H. Ion channels as drug targets in central nervous system disorders. Curr Med Chem 2013; 20:1241-85. [PMID: 23409712 PMCID: PMC3706965 DOI: 10.2174/0929867311320100005] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2012] [Revised: 01/14/2013] [Accepted: 01/18/2013] [Indexed: 12/27/2022]
Abstract
Ion channel targeted drugs have always been related with either the central nervous system (CNS), the peripheral nervous system, or the cardiovascular system. Within the CNS, basic indications of drugs are: sleep disorders, anxiety, epilepsy, pain, etc. However, traditional channel blockers have multiple adverse events, mainly due to low specificity of mechanism of action. Lately, novel ion channel subtypes have been discovered, which gives premises to drug discovery process led towards specific channel subtypes. An example is Na(+) channels, whose subtypes 1.3 and 1.7-1.9 are responsible for pain, and 1.1 and 1.2 - for epilepsy. Moreover, new drug candidates have been recognized. This review is focusing on ion channels subtypes, which play a significant role in current drug discovery and development process. The knowledge on channel subtypes has developed rapidly, giving new nomenclatures of ion channels. For example, Ca(2+)s channels are not any more divided to T, L, N, P/Q, and R, but they are described as Ca(v)1.1-Ca(v)3.3, with even newer nomenclature α1A-α1I and α1S. Moreover, new channels such as P2X1-P2X7, as well as TRPA1-TRPV1 have been discovered, giving premises for new types of analgesic drugs.
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Affiliation(s)
- A M Waszkielewicz
- Department of Bioorganic Chemistry, Chair of Organic Chemistry, Faculty of Pharmacy, Jagiellonian University Medical College, 9 Medyczna Street, 30-688 Krakow, Poland.
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Cross JH, Arora R, Heckemann RA, Gunny R, Chong K, Carr L, Baldeweg T, Differ AM, Lench N, Varadkar S, Sirimanna T, Wassmer E, Hulton SA, Ognjanovic M, Ramesh V, Feather S, Kleta R, Hammers A, Bockenhauer D. Neurological features of epilepsy, ataxia, sensorineural deafness, tubulopathy syndrome. Dev Med Child Neurol 2013; 55:846-56. [PMID: 23924083 PMCID: PMC4298033 DOI: 10.1111/dmcn.12171] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 03/14/2013] [Indexed: 01/30/2023]
Abstract
AIM Recently, we reported a previously unrecognized symptom constellation comprising epilepsy, ataxia, sensorineural deafness, and tubulopathy (EAST syndrome) associated with recessive mutations in the KCNJ10 gene. Here, we provide a detailed characterization of the clinical features of the syndrome to aid patient management with respect to diagnosis, prognostic counselling, and identification of best treatment modalities. METHOD We conducted a retrospective review of the detailed neurological and neuroradiological features of nine children (four females, five males; age range at last examination 6-20y) with genetically proven EAST syndrome. RESULTS All children presented with tonic-clonic seizures in infancy. Later, non-progressive, cerebellar ataxia and hearing loss were noted. Whilst seizures mostly responded well to treatment, ataxia proved to be the most debilitating feature, with three patients non-ambulant. All available magnetic resonance imaging (MRI) revealed subtle symmetrical signal changes in the cerebellar dentate nuclei. Moreover, four patients had a small corpus callosum and brainstem hypoplasia, and three had a small spinal cord. Regional quantitative volumetric analysis of the images confirmed the corpus callosum and brainstem hypoplasia and showed further patterns of variation from the norm. INTERPRETATION The neurological features of EAST syndrome appear to be non-progressive, which is important for prognostic counselling. The spectrum of EAST syndrome includes consistent abnormalities on brain MRI, which may aid diagnosis. Further longitudinal documentation is required to determine the true natural history of the disorder.
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Affiliation(s)
- J Helen Cross
- Neurosciences Unit, Great Ormond Street Hospital for Children NHS Trust and UCL-Institute of Child Health, London, UK.
| | - Ruchi Arora
- Neurosciences Unit, Great Ormond Street Hospital for Children NHS Trust and UCL-Institute of Child HealthLondon, UK
| | | | - Roxana Gunny
- Department of Radiology, Great Ormond Street Hospital for Children NHS Trust and UCL-Institute of Child HealthLondon, UK
| | - Kling Chong
- Department of Radiology, Great Ormond Street Hospital for Children NHS Trust and UCL-Institute of Child HealthLondon, UK
| | - Lucinda Carr
- Neurosciences Unit, Great Ormond Street Hospital for Children NHS Trust and UCL-Institute of Child HealthLondon, UK
| | - Torsten Baldeweg
- Developmental Cognitive Neuroscience Unit, Great Ormond Street Hospital for Children NHS Trust and UCL-Institute of Child HealthLondon, UK
| | - Ann-Marie Differ
- Department of Molecular Genetics, Great Ormond Street Hospital for Children NHS Trust and UCL-Institute of Child HealthLondon, UK
| | - Nicholas Lench
- Department of Molecular Genetics, Great Ormond Street Hospital for Children NHS Trust and UCL-Institute of Child HealthLondon, UK
| | - Sophie Varadkar
- Neurosciences Unit, Great Ormond Street Hospital for Children NHS Trust and UCL-Institute of Child HealthLondon, UK
| | - Tony Sirimanna
- Department of Audiology, Great Ormond Street Hospital for Children NHS Trust and UCL-Institute of Child HealthLondon, UK
| | | | | | | | | | - Sally Feather
- Leeds Teaching Hospitals/University of LeedsLeeds, UK
| | - Robert Kleta
- Department of Nephrology, Great Ormond Street Hospital for Children NHS Trust and UCL-Institute of Child HealthLondon, UK
| | - Alexander Hammers
- The Neurodis FoundationLyon, France,Division of Experimental Medicine, Imperial College LondonLondon, UK
| | - Detlef Bockenhauer
- Department of Nephrology, Great Ormond Street Hospital for Children NHS Trust and UCL-Institute of Child HealthLondon, UK
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Abstract
Many neurologic diseases cause discrete episodic impairment in contrast with progressive deterioration. The symptoms of these episodic disorders exhibit striking variety. Herein we review what is known of the phenotypes, genetics, and pathophysiology of episodic neurologic disorders. Of these, most are genetically complex, with unknown or polygenic inheritance. In contrast, a fascinating panoply of episodic disorders exhibit Mendelian inheritance. We classify episodic Mendelian disorders according to the primary neuroanatomical location affected: skeletal muscle, cardiac muscle, neuromuscular junction, peripheral nerve, or central nervous system (CNS). Most known Mendelian mutations alter genes that encode membrane-bound ion channels. These mutations cause ion channel dysfunction, which ultimately leads to altered membrane excitability as manifested by episodic disease. Other Mendelian disease genes encode proteins essential for ion channel trafficking or stability. These observations have cemented the channelopathy paradigm, in which episodic disorders are conceptualized as disorders of ion channels. However, we expand on this paradigm to propose that dysfunction at the synaptic and neuronal circuit levels may underlie some episodic neurologic entities.
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Affiliation(s)
- Jonathan F Russell
- Department of Neurology, Howard Hughes Medical Institute, School of Medicine, University of California-San Francisco, CA 94158, USA.
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Mayhew IG, Jolly RD, Burnham D, Ridler AL, Poff GJ, Blair HT. Familial episodic ataxia in lambs. N Z Vet J 2013; 61:107-10. [DOI: 10.1080/00480169.2012.717501] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Tomlinson SE, Bostock H, Grinton B, Hanna MG, Kullmann DM, Kiernan MC, Scheffer IE, Berkovic SF, Burke D. In vivo loss of slow potassium channel activity in individuals with benign familial neonatal epilepsy in remission. Brain 2013; 135:3144-52. [PMID: 23065794 DOI: 10.1093/brain/aws241] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Benign familial neonatal epilepsy is a neuronal channelopathy most commonly caused by mutations in KCNQ2, which encodes the K(v)7.2 subunit of the slow K(+) channel. K(v)7.2 is expressed in both central and peripheral nervous systems. Seizures occur in the neonatal period, often in clusters within the first few days of life, and usually remit by 12 months of age. The mechanism of involvement of K(v)7.2 mutations in the process of seizure generation has not been established in vivo. In peripheral axons, K(v)7.2 contributes to the nodal slow K(+) current. The present study aimed to determine whether axonal excitability studies could detect changes in peripheral nerve function related to dysfunction or loss of slow potassium channel activity. Nerve excitability studies were performed on eight adults with KCNQ2 mutations and a history of benign familial neonatal epilepsy, now in remission. Studies detected distinctive changes in peripheral nerve, indicating a reduction in slow K(+) current. Specifically, accommodation to long-lasting depolarizing currents was reduced in mutation carriers by 24% compared with normal controls, and the threshold undershoot after 100 ms depolarizing currents was reduced by 22%. Additional changes in excitability included a reduction in the relative refractory period, an increase in superexcitability and a tendency towards reduced sub-excitability. Modelling of the nerve excitability changes suggested that peripheral nerve hyperexcitability may have been ameliorated by upregulation of other potassium channels. We conclude that subclinical dysfunction of K(v)7.2 in peripheral axons can be reliably detected non-invasively in adulthood. Related alterations in neuronal excitability may contribute to epilepsy associated with KCNQ2 mutations.
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Affiliation(s)
- Susan E Tomlinson
- Department of Neurology, Royal Prince Alfred Hospital, University of Sydney, NSW, Australia.
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26
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Nagappa M, Mundlamuri RC, Satishchandra P, Pal PK. Sleep benefit in a case of Episodic ataxia. Parkinsonism Relat Disord 2012; 18:662-3. [DOI: 10.1016/j.parkreldis.2011.09.018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2011] [Revised: 09/09/2011] [Accepted: 09/20/2011] [Indexed: 10/16/2022]
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Gill JL, Tsai KL, Krey C, Noorai RE, Vanbellinghen JF, Garosi LS, Shelton GD, Clark LA, Harvey RJ. A canine BCAN microdeletion associated with episodic falling syndrome. Neurobiol Dis 2011; 45:130-6. [PMID: 21821125 PMCID: PMC3898273 DOI: 10.1016/j.nbd.2011.07.014] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2011] [Revised: 06/28/2011] [Accepted: 07/20/2011] [Indexed: 12/23/2022] Open
Abstract
Episodic falling syndrome (EFS) is a canine paroxysmal hypertonicity disorder found in Cavalier King Charles spaniels. Episodes are triggered by exercise, stress or excitement and characterized by progressive hypertonicity throughout the thoracic and pelvic limbs, resulting in a characteristic 'deer-stalking' position and/or collapse. We used a genome-wide association strategy to map the EFS locus to a 3.48 Mb critical interval on canine chromosome 7. By prioritizing candidate genes on the basis of biological plausibility, we found that a 15.7 kb deletion in BCAN, encoding the brain-specific extracellular matrix proteoglycan brevican, is associated with EFS. This represents a compelling causal mutation for EFS, since brevican has an essential role in the formation of perineuronal nets governing synapse stability and nerve conduction velocity. Mapping of the deletion breakpoint enabled the development of Multiplex PCR and Multiplex Ligation-dependent Probe Amplification (MLPA) genotyping tests that can accurately distinguish normal, carrier and affected animals. Wider testing of a larger population of CKCS dogs without a history of EFS from the USA revealed that carriers are extremely common (12.9%). The development of molecular genetic tests for the EFS microdeletion will allow the implementation of directed breeding programs aimed at minimizing the number of animals with EFS and enable confirmatory diagnosis and pharmacotherapy of affected dogs.
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Affiliation(s)
- Jennifer L Gill
- Department of Pharmacology, The School of Pharmacy, 29-39 Brunswick Square, London WC1N 1AX, UK
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28
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Tomlinson SE, Tan SV, Kullmann DM, Griggs RC, Burke D, Hanna MG, Bostock H. Nerve excitability studies characterize Kv1.1 fast potassium channel dysfunction in patients with episodic ataxia type 1. ACTA ACUST UNITED AC 2010; 133:3530-40. [PMID: 21106501 DOI: 10.1093/brain/awq318] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Episodic ataxia type 1 is a neuronal channelopathy caused by mutations in the KCNA1 gene encoding the fast K(+) channel subunit K(v)1.1. Episodic ataxia type 1 presents with brief episodes of cerebellar dysfunction and persistent neuromyotonia and is associated with an increased incidence of epilepsy. In myelinated peripheral nerve, K(v)1.1 is highly expressed in the juxtaparanodal axon, where potassium channels limit the depolarizing afterpotential and the effects of depolarizing currents. Axonal excitability studies were performed on patients with genetically confirmed episodic ataxia type 1 to characterize the effects of K(v)1.1 dysfunction on motor axons in vivo. The median nerve was stimulated at the wrist and compound muscle action potentials were recorded from abductor pollicis brevis. Threshold tracking techniques were used to record strength-duration time constant, threshold electrotonus, current/threshold relationship and the recovery cycle. Recordings from 20 patients from eight kindreds with different KCNA1 point mutations were compared with those from 30 normal controls. All 20 patients had a history of episodic ataxia and 19 had neuromyotonia. All patients had similar, distinctive abnormalities: superexcitability was on average 100% higher in the patients than in controls (P < 0.00001) and, in threshold electrotonus, the increase in excitability due to a depolarizing current (20% of threshold) was 31% higher (P < 0.00001). Using these two parameters, the patients with episodic ataxia type 1 and controls could be clearly separated into two non-overlapping groups. Differences between the different KCNA1 mutations were not statistically significant. Studies of nerve excitability can identify K(v)1.1 dysfunction in patients with episodic ataxia type 1. The simple 15 min test may be useful in diagnosis, since it can differentiate patients with episodic ataxia type 1 from normal controls with high sensitivity and specificity.
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Affiliation(s)
- Susan E Tomlinson
- Institute of Neurology, University College London, London WC1N 3BG, UK
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Condamine T, Le Texier L, Howie D, Lavault A, Hill M, Halary F, Cobbold S, Waldmann H, Cuturi MC, Chiffoleau E. Tmem176B and Tmem176A are associated with the immature state of dendritic cells. J Leukoc Biol 2010; 88:507-15. [PMID: 20501748 DOI: 10.1189/jlb.1109738] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
DCs play a central role in the development of innate and adaptive immunity but also in the induction and maintenance of immune tolerance. Identification of factors that govern DC activation, their maturation state, and their capacity to induce proinflammatory or tolerogeneic responses therefore represents a crucial aim of research. We previously identified a new molecule, Tmem176B (which we named TORID initially), as highly expressed in a model of allograft tolerance in the rat. We showed that its overexpression in rat DCs blocked their maturation, suggesting a role for this molecule in the maturation process. To characterize the function of Tmem176B further, we used a split-ubiquitin yeast, two-hybrid system to identify interacting partners and found that Tmem176B associated with itself but also with Tmem176A, a membrane protein similar to Tmem176B. Interestingly, these two molecules showed similar mRNA expression patterns among various murine tissues and immune cells and were both down-regulated following DC maturation. In addition, we showed that in using RNAi, these molecules are both involved in the maintenance of the immature state of the DCs. Taken together, these data suggest that Tmem176B and Tmem176A associate to form multimers and restrain DC maturation. Therefore, these two molecules may represent valid targets to regulate DC function.
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Affiliation(s)
- Thomas Condamine
- INSERM, U643, CHU Nantes, Institut de Transplantation et de Recherche en Transplantation, ITERT, and Université de Nantes, Faculté de Médecine, Nantes, France
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