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Dhar D, Kamble N, Pal PK. Long Latency Reflexes in Clinical Neurology: A Systematic Review. Can J Neurol Sci 2023; 50:751-763. [PMID: 35801267 DOI: 10.1017/cjn.2022.270] [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] [Indexed: 11/05/2022]
Abstract
BACKGROUND Long latency reflexes (LLRs) are impaired in a wide array of clinical conditions. We aimed to illustrate the clinical applications and recent advances of LLR in various neurological disorders from a systematic review of published literature. METHODS We reviewed the literature using appropriately chosen MeSH terms on the database platforms of MEDLINE, Web of Sciences, and Google Scholar for all the articles from 1st January 1975 to 2nd February 2021 using the search terms "long loop reflex", "long latency reflex" and "C-reflex". The included articles were analyzed and reported using synthesis without meta-analysis (SWiM) guidelines. RESULTS Based on our selection criteria, 40 articles were selected for the systematic review. The various diseases included parkinsonian syndromes (11 studies, 217 patients), Huntington's disease (10 studies, 209 patients), myoclonus of varied etiologies (13 studies, 127 patients) including progressive myoclonic epilepsy (5 studies, 63 patients) and multiple sclerosis (6 studies, 200 patients). Patients with parkinsonian syndromes showed large amplitude LLR II response. Enlarged LLR II was also found in myoclonus of various etiologies. LLR II response was delayed or absent in Huntington's disease. Delayed LLR II response was present in multiple sclerosis. Among the other diseases, LLR response varied according to the location of cerebellar lesions while the results were equivocal in patients with essential tremor. CONCLUSIONS Abnormal LLR is observed in many neurological disorders. However, larger systematic studies are required in many neurological disorders in order to establish its role in diagnosis and management.
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Affiliation(s)
- Debjyoti Dhar
- Department of Neurology, National Institute of Mental Health & Neuro Sciences (NIMHANS), Hosur Road, Bangalore 560029, Karnataka, India
| | - Nitish Kamble
- Department of Neurology, National Institute of Mental Health & Neuro Sciences (NIMHANS), Hosur Road, Bangalore 560029, Karnataka, India
| | - Pramod Kumar Pal
- Department of Neurology, National Institute of Mental Health & Neuro Sciences (NIMHANS), Hosur Road, Bangalore 560029, Karnataka, India
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Looking "Cherry Red Spot Myoclonus" in the Eyes: Clinical Phenotype, Treatment Response, and Eye Movements in Sialidosis Type 1. Tremor Other Hyperkinet Mov (N Y) 2022; 11:53. [PMID: 34992946 PMCID: PMC8681143 DOI: 10.5334/tohm.652] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 11/14/2021] [Indexed: 11/20/2022] Open
Abstract
Sialidosis type 1 is a rare lysosomal storage disorder caused by mutations of the neuraminidase gene. Specific features suggesting this condition include myoclonus, ataxia and macular cherry-red spots. However, phenotypic variability exists. Here, we present detailed clinical and video description of three patients with this rare condition. We also provide an in-depth characterization of eye movement abnormalities, as an additional tool to investigate pathophysiological mechanisms and to facilitate diagnosis. In our patients, despite phenotypic differences, eye movement deficits largely localized to the cerebellum.
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Vial F, McGurrin P, Attaripour S, d'Azzo A, Tifft CJ, Toro C, Hallett M. Myoclonus generators in sialidosis. Clin Neurophysiol Pract 2022; 7:169-173. [PMID: 35800887 PMCID: PMC9253402 DOI: 10.1016/j.cnp.2022.05.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Accepted: 05/19/2022] [Indexed: 11/04/2022] Open
Abstract
The cortical origin of myoclonus in sialidosis does not fully explain the phenomena. We used electrophysiology to show a possible subcortical source for the myoclonus. Correct understanding of this physiopathology may help improve treatment.
Objective Sialidosis is an inborn error of metabolism. There is evidence that the myoclonic movements observed in this disorder have a cortical origin, but this mechanism does not fully explain the bilaterally synchronous myoclonus activity frequently observed in many patients. We present evidence of a subcortical basis for synchronous myoclonic phenomena. Methods Electromyographic investigations were undertaken in two molecularly and biochemically confirmed patients with sialidosis type-1. Results The EMG recordings showed clear episodes of bilaterally synchronous myoclonic activity in contralateral homologous muscles. We also observed a high muscular-muscular coherence with near-zero time-lag between these muscles. Conclusion The absence of coherence phase lag between the right-and-left homologous muscles during synchronous events indicates that a unilateral cortical source cannot fully explain the myoclonic activity. There must exist a subcortical mechanism for bilateral synchronization accounting for this phenomenon. Significance Understanding this mechanism may illuminate cortical-subcortical relationships in myoclonus.
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Franceschetti S, Visani E, Rossi Sebastiano D, Duran D, Granata T, Solazzi R, Varotto G, Canafoglia L, Panzica F. Cortico-muscular and cortico-cortical coherence changes resulting from Perampanel treatment in patients with cortical myoclonus. Clin Neurophysiol 2021; 132:1057-1063. [PMID: 33756404 DOI: 10.1016/j.clinph.2021.01.018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Revised: 01/14/2021] [Accepted: 01/30/2021] [Indexed: 10/22/2022]
Abstract
OBJECTIVE To investigate the mechanisms by which Perampanel (PER) reduces the severity of action myoclonus, we studied on MEG signals the changes occurring in cortico-muscular coherence (CMC) and cortico-cortical connectivity in patients with progressive myoclonus epilepsies. METHODS The subjects performed an isometric extension of the hand; CMC and cortico-cortical connectivity were assessed using autoregressive models and generalized partial-directed coherence. The contralateral (Co) sensors showing average CMC values >0.7 of the maximum (set to 1) were grouped as central (C) regions of interest (ROI), while adjacent sensors showing CMC values >0.3 were grouped as Surrounding (Sr) ROIs. RESULTS Under PER treatment, CMC decreased on Co C and Sr ROIs, but also on homologous ipsilateral (Ip) ROIs; out-degrees and betweenness centrality increased in Co ROIs and decreased in Ip ROIs. The flow from Ip to Co ROIs and from activated muscles to Ip C ROI decreased. CONCLUSION The improvement of myoclonus corresponded to decreased CMC and recovered leadership of the cortical regions directly involved in the motor task, with a reduced interference of ipsilateral areas. SIGNIFICANCE Our study highlights on mechanisms suitable to treating myoclonus and suggests the role of a reduced local synchronization together a better control of distant synaptic effects.
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Affiliation(s)
- S Franceschetti
- Neurophysiopathology, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - E Visani
- Department of Epileptology, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - D Rossi Sebastiano
- Neurophysiopathology, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - D Duran
- Department of Epileptology, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - T Granata
- Department of Epileptology, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy; Department of Pediatric Neuroscience, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - R Solazzi
- Department of Epileptology, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy; Department of Pediatric Neuroscience, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - G Varotto
- Unit of Clinical and Biomedical Engineering, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - L Canafoglia
- Department of Epileptology, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy.
| | - F Panzica
- Unit of Clinical and Biomedical Engineering, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
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Diagnosis and Management of Type 1 Sialidosis: Clinical Insights from Long-Term Care of Four Unrelated Patients. Brain Sci 2020; 10:brainsci10080506. [PMID: 32752208 PMCID: PMC7465165 DOI: 10.3390/brainsci10080506] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Revised: 07/23/2020] [Accepted: 07/24/2020] [Indexed: 11/21/2022] Open
Abstract
Background: Sialidosis is a rare autosomal recessive disease caused by NEU1 mutations, leading to neuraminidase deficiency and accumulation of sialic acid-containing oligosaccharides and glycopeptides into the tissues. Sialidosis is divided into two clinical entities, depending on residual enzyme activity, and can be distinguished according to age of onset, clinical features, and progression. Type 1 sialidosis is the milder, late-onset form, also known as non-dysmorphic sialidosis. It is commonly characterized by progressive myoclonus, ataxia, and a macular cherry-red spot. As a rare condition, the diagnosis is often only made after few years from onset, and the clinical management might prove difficult. Furthermore, the information in the literature on the long-term course is scarce. Case presentations: We describe a comprehensive clinical, neuroradiological, ophthalmological, and electrophysiological history of four unrelated patients affected by type 1 sialidosis. The long-term care and novel clinical and neuroradiological insights are discussed. Discussion and conclusions: We report the longest follow-up (up to 30 years) ever described in patients with type 1 sialidosis. During the course, we observed a high degree of motor and speech disability with preserved cognitive functions. Among the newest antiseizure medication, perampanel (PER) was proven to be effective in controlling myoclonus and tonic–clonic seizures, confirming it is a valid therapeutic option for these patients. Brain magnetic resonance imaging (MRI) disclosed new findings, including bilateral gliosis of cerebellar folia and of the occipital white matter. In addition, a newly reported variant (c.914G > A) is described.
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Abstract
The progressive myoclonic epilepsies (PMEs) represent a rare but devastating group of syndromes characterized by epileptic myoclonus, typically action-induced seizures, neurological regression, medically refractory epilepsy, and a variety of other signs and symptoms depending on the specific syndrome. Most of the PMEs begin in children who are developing as expected, with the onset of the disorder heralded by myoclonic and other seizure types. The conditions are considerably heterogenous, but medical intractability to epilepsy, particularly myoclonic seizures, is a core feature. With the increasing use of molecular genetic techniques, mutations and their abnormal protein products are being delineated, providing a basis for disease-based therapy. However, genetic and enzyme replacement or substrate removal are in the nascent stage, and the primary therapy is through antiepileptic drugs. Epilepsy in children with progressive myoclonic seizures is notoriously difficult to treat. The disorder is rare, so few double-blinded, placebo-controlled trials have been conducted in PME, and drugs are chosen based on small open-label trials or extrapolation of data from drug trials of other syndromes with myoclonic seizures. This review discusses the major PME syndromes and their neurogenetic basis, pathophysiological underpinning, electroencephalographic features, and currently available treatments.
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Affiliation(s)
- Gregory L Holmes
- Department of Neurological Sciences, Larner College of Medicine, University of Vermont College of Medicine, Stafford Hall, 118C, Burlington, VT, 05405, USA.
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Caciotti A, Melani F, Tonin R, Cellai L, Catarzi S, Procopio E, Chilleri C, Mavridou I, Michelakakis H, Fioravanti A, d'Azzo A, Guerrini R, Morrone A. Type I sialidosis, a normosomatic lysosomal disease, in the differential diagnosis of late-onset ataxia and myoclonus: An overview. Mol Genet Metab 2020; 129:47-58. [PMID: 31711734 DOI: 10.1016/j.ymgme.2019.09.005] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Revised: 09/23/2019] [Accepted: 09/23/2019] [Indexed: 01/12/2023]
Abstract
Lysosomal storage diseases (LSDs) are rare to extremely rare monogenic disorders. Their incidence, however, has probably been underestimated owing to their complex clinical manifestations. Sialidosis is a prototypical LSD inherited as an autosomal recessive trait and caused by mutations in the NEU1 gene that result in a deficiency of alpha-N-acetyl neuraminidase 1 (NEU1). Two basic forms of this disease, type I and type II, are known. The dysmorphic type II form features LSD symptoms including congenital hydrops, dysmorphogenetic traits, hepato-splenomegaly and severe intellectual disability. The diagnosis is more challenging in the normosomatic type I forms, whose clinical findings at onset include ocular defects, ataxia and generalized myoclonus. Here we report the clinical, biochemical and molecular analysis of five patients with sialidosis type I. Two patients presented novel NEU1 mutations. One of these patients was compound heterozygous for two novel NEU1 missense mutations: c.530A>T (p.Asp177Val) and c.1010A>G (p.His337Arg), whereas a second patient was compound heterozygous for a known mutation and a novel c.839G>A (p.Arg280Gln) mutation. We discuss the impact of these new mutations on the structural properties of NEU1. We also review available clinical reports of patients with sialidosis type I, with the aim of identifying the most frequent initial clinical manifestations and achieving more focused diagnoses.
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Affiliation(s)
- Anna Caciotti
- Paediatric Neurology Unit and Laboratories, Meyer Children's Hospital, Florence, Italy
| | - Federico Melani
- Paediatric Neurology Unit and Laboratories, Meyer Children's Hospital, Florence, Italy
| | - Rodolfo Tonin
- Paediatric Neurology Unit and Laboratories, Meyer Children's Hospital, Florence, Italy
| | - Lucrezia Cellai
- Paediatric Neurology Unit and Laboratories, Meyer Children's Hospital, Florence, Italy
| | - Serena Catarzi
- Paediatric Neurology Unit and Laboratories, Meyer Children's Hospital, Florence, Italy; Department of NEUROFARBA, University of Florence, Florence, Italy
| | - Elena Procopio
- Metabolic and Muscular Unit, Meyer Children's Hospital, Florence, Italy
| | - Chiara Chilleri
- Paediatric Neurology Unit and Laboratories, Meyer Children's Hospital, Florence, Italy
| | - Irene Mavridou
- Division of Enzymology and Cellular Function, Institute of Child Health, Athens, Greece
| | - Helen Michelakakis
- Division of Enzymology and Cellular Function, Institute of Child Health, Athens, Greece
| | - Antonella Fioravanti
- Structural Biology, Research Center-VIB (Flanders Interuniversity Institute for Biotechnology), University of Brussels, Belgium
| | - Alessandra d'Azzo
- Dep. of Genetics, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Renzo Guerrini
- Paediatric Neurology Unit and Laboratories, Meyer Children's Hospital, Florence, Italy; Department of NEUROFARBA, University of Florence, Florence, Italy
| | - Amelia Morrone
- Paediatric Neurology Unit and Laboratories, Meyer Children's Hospital, Florence, Italy; Department of NEUROFARBA, University of Florence, Florence, Italy.
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Bhat S, Ganesh S. New discoveries in progressive myoclonus epilepsies: a clinical outlook. Expert Rev Neurother 2018; 18:649-667. [DOI: 10.1080/14737175.2018.1503949] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Shweta Bhat
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology, Kanpur, India
| | - Subramaniam Ganesh
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology, Kanpur, India
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SCA13 causes dominantly inherited non-progressive myoclonus ataxia. Parkinsonism Relat Disord 2017; 38:80-84. [PMID: 28216058 DOI: 10.1016/j.parkreldis.2017.02.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Revised: 01/25/2017] [Accepted: 02/09/2017] [Indexed: 01/26/2023]
Abstract
INTRODUCTION Spinocerebellar ataxia 13 (SCA13) is a rare autosomal dominant cerebellar ataxia. To our knowledge, its association to movement disorders has never been described. We aimed at reporting 8 new SCA13 cases with a focus on movement disorders especially myoclonus. METHODS We performed a detailed neurological examination and neurophysiological recording in 8 patients consecutively diagnosed with SCA13 between December 2013 and October 2015 and followed up in two French tertiary centers. RESULTS We identified mild subcortical myoclonus in all patients, with a homogenous clinical and electrophysiological pattern. Myoclonus ataxia was very slowly progressive, like the other symptoms of the disease, whatever the age of onset. Patients with R423H mutation had an earlier age of onset than patients with R420H mutation. CONCLUSIONS Myoclonus appears to be frequent in SCA13. SCA13 should be considered facing non-progressive autosomal dominant myoclonus ataxia, and polymyographic recording should be included in the diagnosis work.
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10
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Franceschetti S, Canafoglia L, Rotondi F, Visani E, Granvillano A, Panzica F. The network sustaining action myoclonus: a MEG-EMG study in patients with EPM1. BMC Neurol 2016; 16:214. [PMID: 27821136 PMCID: PMC5100097 DOI: 10.1186/s12883-016-0738-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Accepted: 11/01/2016] [Indexed: 11/12/2022] Open
Abstract
Background To explore the cortical network sustaining action myoclonus and to found markers of the resulting functional impairment, we evaluated the distribution of the cortico-muscular coherence (CMC) and the frequency of coherent cortical oscillations with magnetoencephalography (MEG). All patients had EPM1 (Unverricht-Lundborg) disease known to present with prominent and disabling movement-activated myoclonus. Methods Using autoregressive models, we evaluated CMC on MEG sensors grouped in regions of interests (ROIs) above the main cortical areas. The movement was a repeated sustained isometric extension of the right hand and right foot. We compared the data obtained in 10 EPM1 patients with those obtained in 10 age-matched controls. Results As expected, CMC in beta band was significantly higher in EPM1 patients compared to controls in the ROIs exploring the sensorimotor cortex, but, it was also significantly higher in adjacent ROIs ipsilateral and contralateral to the activated limb. Moreover, the beta-CMC peak occurred at frequencies significantly slower and more stable frequencies in EPM1 patients with respect to controls. The frequency of the beta-CMC peak inversely correlated with the severity of myoclonus. Conclusions the high and spatially extended beta-CMC peaking in a restricted range of low-beta frequencies in EPM1 patients, suggest that action myoclonus may result not only from an enhanced local synchronization but also from a specific oscillatory activity involving an expanded neuronal pool. The significant relationship between beta-CMC peak frequency and the severity of the motor impairment can represent a useful neurophysiological marker for the patients’ evaluation and follow-up.
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Affiliation(s)
- Silvana Franceschetti
- Department of Neurophysiology, Epilepsy Centre, C. Besta Neurological Institute IRCCS Foundation, Via Celoria 11, 20133, Milan, Italy.
| | - Laura Canafoglia
- Department of Neurophysiology, Epilepsy Centre, C. Besta Neurological Institute IRCCS Foundation, Via Celoria 11, 20133, Milan, Italy
| | - Fabio Rotondi
- Department of Neurophysiology, Epilepsy Centre, C. Besta Neurological Institute IRCCS Foundation, Via Celoria 11, 20133, Milan, Italy.,Department of Informatics, Bioengineering, Robotics and System Engineering (DIBRIS), University of Genova, Genova, Italy
| | - Elisa Visani
- Department of Neurophysiology, Epilepsy Centre, C. Besta Neurological Institute IRCCS Foundation, Via Celoria 11, 20133, Milan, Italy
| | - Alice Granvillano
- Department of Neurophysiology, Epilepsy Centre, C. Besta Neurological Institute IRCCS Foundation, Via Celoria 11, 20133, Milan, Italy
| | - Ferruccio Panzica
- Department of Neurophysiology, Epilepsy Centre, C. Besta Neurological Institute IRCCS Foundation, Via Celoria 11, 20133, Milan, Italy
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Franceschetti S, Michelucci R, Canafoglia L, Striano P, Gambardella A, Magaudda A, Tinuper P, La Neve A, Ferlazzo E, Gobbi G, Giallonardo AT, Capovilla G, Visani E, Panzica F, Avanzini G, Tassinari CA, Bianchi A, Zara F. Progressive myoclonic epilepsies: definitive and still undetermined causes. Neurology 2014; 82:405-11. [PMID: 24384641 DOI: 10.1212/wnl.0000000000000077] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVE To define the clinical spectrum and etiology of progressive myoclonic epilepsies (PMEs) in Italy using a database developed by the Genetics Commission of the Italian League against Epilepsy. METHODS We collected clinical and laboratory data from patients referred to 25 Italian epilepsy centers regardless of whether a positive causative factor was identified. PMEs of undetermined origins were grouped using 2-step cluster analysis. RESULTS We collected clinical data from 204 patients, including 77 with a diagnosis of Unverricht-Lundborg disease and 37 with a diagnosis of Lafora body disease; 31 patients had PMEs due to rarer genetic causes, mainly neuronal ceroid lipofuscinoses. Two more patients had celiac disease. Despite extensive investigation, we found no definitive etiology for 57 patients. Cluster analysis indicated that these patients could be grouped into 2 clusters defined by age at disease onset, age at myoclonus onset, previous psychomotor delay, seizure characteristics, photosensitivity, associated signs other than those included in the cardinal definition of PME, and pathologic MRI findings. CONCLUSIONS Information concerning the distribution of different genetic causes of PMEs may provide a framework for an updated diagnostic workup. Phenotypes of the patients with PME of undetermined cause varied widely. The presence of separate clusters suggests that novel forms of PME are yet to be clinically and genetically characterized.
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Affiliation(s)
- Silvana Franceschetti
- From the Department of Neurophysiopathology and Epilepsy Centre (S.F., L.C., E.V., F.P., G.A.), IRCCS Foundation C. Besta Neurological Institute, Milan; Unit of Neurology (R.M.), IRCCS Institute of Neurological Sciences, Bellaria Hospital, Bologna; Pediatric Neurology and Muscular Diseases Unit (P.S.), DINOGMI-Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, G. Gaslini Institute; Department of Medical and Surgical Sciences (A.G., E.F.), Magna Graecia University, Catanzaro; Institute of Neurological Sciences (A.G.), National Research Council, Mangone, Cosenza; Epilepsy Centre (A.M.), Department of Neuroscience, University of Messina; IRCCS Institute of Neurological Sciences and Department of Biomedical and Neuromotor Sciences (P.T.), University of Bologna; Epilepsy Centre (A.L.N.), Azienda Ospedaliero Universitaria Consorziale, Dipartimento di Scienze Mediche di Base, Neuroscienze ed Organi di Senso, Policlinico, Bari; Child Neurology Unit (G.G.), IRCCS delle Scienze Neurologiche, Bologna; Department of Neurology and Psychiatry (A.T.G.), Neurology Unit, La Sapienza University, Rome; Epilepsy Center (G.C.), Department of Child Neuropsychiatry, C. Poma Hospital, Mantua; University of Bologna (C.A.T.); Department of Neurology and Epilepsy Centre (A.B.), San Donato Hospital, Arezzo; and Istituto Gaslini (F.Z.), Laboratory of Neurogenetics, Genoa, Italy. Coinvestigators are listed on the Neurology® Web site at www.neurology.org
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Turnbull J, Girard JM, Lohi H, Chan EM, Wang P, Tiberia E, Omer S, Ahmed M, Bennett C, Chakrabarty A, Tyagi A, Liu Y, Pencea N, Zhao X, Scherer SW, Ackerley CA, Minassian BA. Early-onset Lafora body disease. ACTA ACUST UNITED AC 2012; 135:2684-98. [PMID: 22961547 DOI: 10.1093/brain/aws205] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The most common progressive myoclonus epilepsies are the late infantile and late infantile-variant neuronal ceroid lipofuscinoses (onset before the age of 6 years), Unverricht-Lundborg disease (onset after the age of 6 years) and Lafora disease. Lafora disease is a distinct disorder with uniform course: onset in teenage years, followed by progressively worsening myoclonus, seizures, visual hallucinations and cognitive decline, leading to a vegetative state in status myoclonicus and death within 10 years. Biopsy reveals Lafora bodies, which are pathognomonic and not seen with any other progressive myoclonus epilepsies. Lafora bodies are aggregates of polyglucosans, poorly constructed glycogen molecules with inordinately long strands that render them insoluble. Lafora disease is caused by mutations in the EPM2A or EPM2B genes, encoding the laforin phosphatase and the malin ubiquitin ligase, respectively, two cytoplasmically active enzymes that regulate glycogen construction, ensuring symmetric expansion into a spherical shape, essential to its solubility. In this work, we report a new progressive myoclonus epilepsy associated with Lafora bodies, early-onset Lafora body disease, map its locus to chromosome 4q21.21, identify its gene and mutation and characterize the relationship of its gene product with laforin and malin. Early-onset Lafora body disease presents early, at 5 years, with dysarthria, myoclonus and ataxia. The combination of early-onset and early dysarthria strongly suggests late infantile-variant neuronal ceroid lipofuscinosis, not Lafora disease. Pathology reveals no ceroid lipofuscinosis, but Lafora bodies. The subsequent course is a typical progressive myoclonus epilepsy, though much more protracted than any infantile neuronal ceroid lipofuscinosis, or Lafora disease, patients living into the fourth decade. The mutation, c.781T>C (Phe261Leu), is in a gene of unknown function, PRDM8. We show that the PRDM8 protein interacts with laforin and malin and causes translocation of the two proteins to the nucleus. We find that Phe261Leu-PRDM8 results in excessive sequestration of laforin and malin in the nucleus and that it therefore likely represents a gain-of-function mutation that leads to an effective deficiency of cytoplasmic laforin and malin. We have identified a new progressive myoclonus epilepsy with Lafora bodies, early-onset Lafora body disease, 101 years after Lafora disease was first described. The results to date suggest that PRDM8, the early-onset Lafora body disease protein, regulates the cytoplasmic quantities of the Lafora disease enzymes.
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Affiliation(s)
- Julie Turnbull
- Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Ontario M5G 1L7, Canada
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