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The efficacy of combining topiramate and 4-aminopyridine to reduce relapses and interictal progression in two cases of episodic ataxia type 2. Neurol Sci 2022; 43:5099-5101. [DOI: 10.1007/s10072-022-06144-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Accepted: 05/13/2022] [Indexed: 10/18/2022]
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2
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Ondruskova N, Cechova A, Hansikova H, Honzik T, Jaeken J. Congenital disorders of glycosylation: Still "hot" in 2020. Biochim Biophys Acta Gen Subj 2020; 1865:129751. [PMID: 32991969 DOI: 10.1016/j.bbagen.2020.129751] [Citation(s) in RCA: 72] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 08/12/2020] [Accepted: 08/27/2020] [Indexed: 12/11/2022]
Abstract
BACKGROUND Congenital disorders of glycosylation (CDG) are inherited metabolic diseases caused by defects in the genes important for the process of protein and lipid glycosylation. With the ever growing number of the known subtypes and discoveries regarding the disease mechanisms and therapy development, it remains a very active field of study. SCOPE OF REVIEW This review brings an update on the CDG-related research since 2017, describing the novel gene defects, pathobiomechanisms, biomarkers and the patients' phenotypes. We also summarize the clinical guidelines for the most prevalent disorders and the current therapeutical options for the treatable CDG. MAJOR CONCLUSIONS In the majority of the 23 new CDG, neurological involvement is associated with other organ disease. Increasingly, different aspects of cellular metabolism (e.g., autophagy) are found to be perturbed in multiple CDG. GENERAL SIGNIFICANCE This work highlights the recent trends in the CDG field and comprehensively overviews the up-to-date clinical recommendations.
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Affiliation(s)
- Nina Ondruskova
- Department of Paediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague, Czech Republic
| | - Anna Cechova
- Department of Paediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague, Czech Republic
| | - Hana Hansikova
- Department of Paediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague, Czech Republic
| | - Tomas Honzik
- Department of Paediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague, Czech Republic.
| | - Jaak Jaeken
- Department of Paediatrics and Centre for Metabolic Diseases, KU Leuven and University Hospital Leuven, Leuven, Belgium.
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Abstract
Cerebellar ataxia can be caused by a variety of disorders, including degenerative processes, autoimmune and paraneoplastic illness as well as by gene mutations inherited in autosomal dominant, autosomal recessive, or X-linked fashions. In this review, we highlight the treatments for cerebellar ataxia in a systematic way, to provide guidance for clinicians who treat patients with cerebellar ataxia. In addition, we review therapies currently under development for ataxia, which we feel is currently one of the most exciting fields in neurology.
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4
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Therapeutic approaches in Congenital Disorders of Glycosylation (CDG) involving N-linked glycosylation: an update. Genet Med 2020; 22:268-279. [PMID: 31534212 PMCID: PMC8720509 DOI: 10.1038/s41436-019-0647-2] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2019] [Accepted: 08/20/2019] [Indexed: 02/07/2023] Open
Abstract
Congenital disorders of glycosylation (CDG) are a group of clinically and genetically heterogeneous metabolic disorders. Over 150 CDG types have been described. Most CDG types are ultrarare disorders. CDG types affecting N-glycosylation are the most common type of CDG with emerging therapeutic possibilities. This review is an update on the available therapies for disorders affecting the N-linked glycosylation pathway. In the first part of the review, we highlight the clinical presentation, general principles of management, and disease-specific therapies for N-linked glycosylation CDG types, organized by organ system. The second part of the review focuses on the therapeutic strategies currently available and under development. We summarize the successful (pre-) clinical application of nutritional therapies, transplantation, activated sugars, gene therapy, and pharmacological chaperones and outline the anticipated expansion of the therapeutic possibilities in CDG. We aim to provide a comprehensive update on the treatable aspects of CDG types involving N-linked glycosylation, with particular emphasis on disease-specific treatment options for the involved organ systems; call for natural history studies; and present current and future therapeutic strategies for CDG.
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5
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Martínez-Monseny AF, Bolasell M, Callejón-Póo L, Cuadras D, Freniche V, Itzep DC, Gassiot S, Arango P, Casas-Alba D, de la Morena E, Corral J, Montero R, Pérez-Cerdá C, Pérez B, Artuch R, Jaeken J, Serrano M. AZATAX: Acetazolamide safety and efficacy in cerebellar syndrome in PMM2 congenital disorder of glycosylation (PMM2-CDG). Ann Neurol 2019; 85:740-751. [PMID: 30873657 DOI: 10.1002/ana.25457] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2018] [Revised: 03/03/2019] [Accepted: 03/05/2019] [Indexed: 12/26/2022]
Abstract
OBJECTIVE Phosphomannomutase deficiency (PMM2 congenital disorder of glycosylation [PMM2-CDG]) causes cerebellar syndrome and strokelike episodes (SLEs). SLEs are also described in patients with gain-of-function mutations in the CaV2.1 channel, for which acetazolamide therapy is suggested. Impairment in N-glycosylation of CaV2.1 promotes gain-of-function effects and may participate in cerebellar syndrome in PMM2-CDG. AZATAX was designed to establish whether acetazolamide is safe and improves cerebellar syndrome in PMM2-CDG. METHODS A clinical trial included PMM2-CDG patients, with a 6-month first-phase single acetazolamide therapy group, followed by a randomized 5-week withdrawal phase. Safety was assessed. The primary outcome measure was improvement in the International Cooperative Ataxia Rating Scale (ICARS). Other measures were the Nijmegen Pediatric CDG Rating Scale (NPCRS), a syllable repetition test (PATA test), and cognitive scores. RESULTS Twenty-four patients (mean age = 12.3 ± 4.5 years) were included, showing no serious adverse events. Thirteen patients required dose adjustment due to low bicarbonate or asthenia. There were improvements on ICARS (34.9 ± 23.2 vs 40.7 ± 24.8, effect size = 1.48, 95% confidence interval [CI] = 4.0-7.6, p < 0.001), detected at 6 weeks in 18 patients among the 20 responders, on NPCRS (95% CI = 0.3-1.6, p = 0.013) and on the PATA test (95% CI = 0.5-3.0, p = 0.006). Acetazolamide improved prothrombin time, factor X, and antithrombin. Clinical severity, epilepsy, and lipodystrophy predicted greater response. The randomized withdrawal phase showed ICARS worsening in the withdrawal group (effect size = 1.46, 95% CI = 2.65-7.52, p = 0.001). INTERPRETATION AZATAX is the first clinical trial of PMM2-CDG. Acetazolamide is well tolerated and effective for motor cerebellar syndrome. Its ability to prevent SLEs and its long-term effects on kidney function should be addressed in future studies. Ann Neurol 2019;85:740-751.
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Affiliation(s)
- Antonio F Martínez-Monseny
- Genetic Medicine Department and Pediatric Institute of Rare Diseases, Sant Joan de Déu Hospital Research Institute, Barcelona, Spain
| | - Mercè Bolasell
- Genetic Medicine Department and Pediatric Institute of Rare Diseases, Sant Joan de Déu Hospital Research Institute, Barcelona, Spain
| | - Laura Callejón-Póo
- Neuropsychology Unit, Neuroesplugues, Esplugues de Llobregat, Barcelona, Spain
| | - Daniel Cuadras
- Statistics Department, Sant Joan de Déu Foundation, Barcelona, Spain
| | - Verónica Freniche
- Neuropsychology Unit, Neuroesplugues, Esplugues de Llobregat, Barcelona, Spain
| | - Débora C Itzep
- Neuropediatric Department, Sant Joan de Déu Hospital Research Institute, Barcelona, Spain
| | - Susanna Gassiot
- Hematology Laboratory, Sant Joan de Déu Hospital Research Institute, Barcelona, Spain
| | - Pedro Arango
- Nephrology Department, Sant Joan de Déu Hospital Research Institute, Barcelona, Spain
| | - Didac Casas-Alba
- Genetic Medicine Department and Pediatric Institute of Rare Diseases, Sant Joan de Déu Hospital Research Institute, Barcelona, Spain
| | - Eugenia de la Morena
- Hematology and Medical Oncology Service, Morales Meseguer University Hospital, Regional Blood Donation Center, Murcia University, IMIB-Arrixaca, U-765, Center for Biomedical Research on Rare Diseases, Murcia, Spain
| | - Javier Corral
- Hematology and Medical Oncology Service, Morales Meseguer University Hospital, Regional Blood Donation Center, Murcia University, IMIB-Arrixaca, U-765, Center for Biomedical Research on Rare Diseases, Murcia, Spain
| | - Raquel Montero
- Clinical Biochemistry Department, Sant Joan de Déu Hospital Research Institute, Barcelona, Spain.,U-703, Center for Biomedical Research on Rare Diseases, Instituto de Salud Carlos III, Sant Joan de Déu Hospital, Barcelona, Spain
| | - Celia Pérez-Cerdá
- Diagnosis of Molecular Diseases Center, Autonomous University of Madrid, U-746, Center for Biomedical Research on Rare Diseases, Instituto de Salud Carlos III, IdiPAZ, Madrid, Spain
| | - Belén Pérez
- Diagnosis of Molecular Diseases Center, Autonomous University of Madrid, U-746, Center for Biomedical Research on Rare Diseases, Instituto de Salud Carlos III, IdiPAZ, Madrid, Spain
| | - Rafael Artuch
- Clinical Biochemistry Department, Sant Joan de Déu Hospital Research Institute, Barcelona, Spain.,U-703, Center for Biomedical Research on Rare Diseases, Instituto de Salud Carlos III, Sant Joan de Déu Hospital, Barcelona, Spain
| | - Jaak Jaeken
- Center for Metabolic Disease, University Hospital Gasthuisberg, Catholic University of Leuven, Leuven, Belgium
| | - Mercedes Serrano
- Genetic Medicine Department and Pediatric Institute of Rare Diseases, Sant Joan de Déu Hospital Research Institute, Barcelona, Spain.,Neuropediatric Department, Sant Joan de Déu Hospital Research Institute, Barcelona, Spain.,U-703, Center for Biomedical Research on Rare Diseases, Instituto de Salud Carlos III, Sant Joan de Déu Hospital, Barcelona, Spain
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6
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Luo X, Rosenfeld JA, Yamamoto S, Harel T, Zuo Z, Hall M, Wierenga KJ, Pastore MT, Bartholomew D, Delgado MR, Rotenberg J, Lewis RA, Emrick L, Bacino CA, Eldomery MK, Coban Akdemir Z, Xia F, Yang Y, Lalani SR, Lotze T, Lupski JR, Lee B, Bellen HJ, Wangler MF. Clinically severe CACNA1A alleles affect synaptic function and neurodegeneration differentially. PLoS Genet 2017; 13:e1006905. [PMID: 28742085 PMCID: PMC5557584 DOI: 10.1371/journal.pgen.1006905] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Revised: 08/15/2017] [Accepted: 07/03/2017] [Indexed: 01/04/2023] Open
Abstract
Dominant mutations in CACNA1A, encoding the α-1A subunit of the neuronal P/Q type voltage-dependent Ca2+ channel, can cause diverse neurological phenotypes. Rare cases of markedly severe early onset developmental delay and congenital ataxia can be due to de novo CACNA1A missense alleles, with variants affecting the S4 transmembrane segments of the channel, some of which are reported to be loss-of-function. Exome sequencing in five individuals with severe early onset ataxia identified one novel variant (p.R1673P), in a girl with global developmental delay and progressive cerebellar atrophy, and a recurrent, de novo p.R1664Q variant, in four individuals with global developmental delay, hypotonia, and ophthalmologic abnormalities. Given the severity of these phenotypes we explored their functional impact in Drosophila. We previously generated null and partial loss-of-function alleles of cac, the homolog of CACNA1A in Drosophila. Here, we created transgenic wild type and mutant genomic rescue constructs with the two noted conserved point mutations. The p.R1673P mutant failed to rescue cac lethality, displayed a gain-of-function phenotype in electroretinograms (ERG) recorded from mutant clones, and evolved a neurodegenerative phenotype in aging flies, based on ERGs and transmission electron microscopy. In contrast, the p.R1664Q variant exhibited loss of function and failed to develop a neurodegenerative phenotype. Hence, the novel R1673P allele produces neurodegenerative phenotypes in flies and human, likely due to a toxic gain of function.
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Affiliation(s)
- Xi Luo
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States of America
| | - Jill A. Rosenfeld
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States of America
| | - Shinya Yamamoto
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States of America
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, United States of America
| | - Tamar Harel
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States of America
- Baylor-Hopkins Center for Mendelian Genomics, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States of America
| | - Zhongyuan Zuo
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States of America
| | - Melissa Hall
- University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States of America
| | - Klaas J. Wierenga
- University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States of America
| | - Matthew T. Pastore
- Nationwide Children’s Hospital & The Ohio State University, Columbus, OH, United States of America
| | - Dennis Bartholomew
- Nationwide Children’s Hospital & The Ohio State University, Columbus, OH, United States of America
| | - Mauricio R. Delgado
- Department of Neurology and Neurotherapeutics, UT Southwestern Medical Center andTexas Scottish Rite Hospital, Dallas, TX, United States of America
| | | | - Richard Alan Lewis
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States of America
- Baylor-Hopkins Center for Mendelian Genomics, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States of America
- Department of Pediatrics, Baylor College of Medicine, Houston, TX, United States of America
- Texas Children’s Hospital, Houston, TX, United States of America
| | - Lisa Emrick
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States of America
- Department of Pediatrics, Baylor College of Medicine, Houston, TX, United States of America
| | - Carlos A. Bacino
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States of America
| | - Mohammad K. Eldomery
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States of America
- Baylor-Hopkins Center for Mendelian Genomics, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States of America
| | - Zeynep Coban Akdemir
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States of America
- Baylor-Hopkins Center for Mendelian Genomics, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States of America
| | - Fan Xia
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States of America
| | - Yaping Yang
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States of America
| | - Seema R. Lalani
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States of America
| | - Timothy Lotze
- Department of Pediatrics, Baylor College of Medicine, Houston, TX, United States of America
| | - James R. Lupski
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States of America
- Baylor-Hopkins Center for Mendelian Genomics, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States of America
- Department of Pediatrics, Baylor College of Medicine, Houston, TX, United States of America
- Texas Children’s Hospital, Houston, TX, United States of America
| | - Brendan Lee
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States of America
| | - Hugo J. Bellen
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States of America
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, United States of America
- Howard Hughes Medical Institute, Houston TX, United States of America
| | - Michael F. Wangler
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States of America
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, United States of America
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7
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Effects of dalfampridine on attacks in patients with episodic ataxia type 2: an observational study. J Neurol 2012. [DOI: 10.1007/s00415-012-6764-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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8
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Rajakulendran S, Kaski D, Hanna MG. Neuronal P/Q-type calcium channel dysfunction in inherited disorders of the CNS. Nat Rev Neurol 2012; 8:86-96. [PMID: 22249839 DOI: 10.1038/nrneurol.2011.228] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The past two decades have witnessed the emergence of a new and expanding field of neurological diseases--the genetic ion channelopathies. These disorders arise from mutations in genes that encode ion channel subunits, and manifest as paroxysmal attacks involving the brain or spinal cord, and/or muscle. The voltage-gated P/Q-type calcium channel (P/Q channel) is highly expressed in the cerebellum, hippocampus and cortex of the mammalian brain. The P/Q channel has a fundamental role in mediating fast synaptic transmission at central and peripheral nerve terminals. Autosomal dominant mutations in the CACNA1A gene, which encodes voltage-gated P/Q-type calcium channel subunit α(1) (the principal pore-forming subunit of the P/Q channel) are associated with episodic and progressive forms of cerebellar ataxia, familial hemiplegic migraine, vertigo and epilepsy. This Review considers, from both a clinical and genetic perspective, the various neurological phenotypes arising from inherited P/Q channel dysfunction, with a focus on recent advances in the understanding of the pathogenetic mechanisms underlying these disorders.
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Affiliation(s)
- Sanjeev Rajakulendran
- Medical Research Council Center for Neuromuscular Diseases, Box 102, National Hospital for Neurology and Neurosurgery, Queen Square, London WC1N 3BG, UK
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9
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Strupp M, Kalla R, Claassen J, Adrion C, Mansmann U, Klopstock T, Freilinger T, Neugebauer H, Spiegel R, Dichgans M, Lehmann-Horn F, Jurkat-Rott K, Brandt T, Jen JC, Jahn K. A randomized trial of 4-aminopyridine in EA2 and related familial episodic ataxias. Neurology 2011; 77:269-75. [PMID: 21734179 DOI: 10.1212/wnl.0b013e318225ab07] [Citation(s) in RCA: 120] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
OBJECTIVE The therapeutic effects of 4-aminopyridine (4AP) were investigated in a randomized, double-blind, crossover trial in 10 subjects with familial episodic ataxia with nystagmus. METHODS After randomization, placebo or 4AP (5 mg 3 times daily) was administered for 2 3-month-long treatment periods separated by a 1-month-long washout period. The primary outcome measure was the number of ataxia attacks per month; the secondary outcome measures were the attack duration and patient-reported quality of life (Vestibular Disorders Activities of Daily Living Scale [VDADL]). Nonparametric tests and a random-effects model were used for statistical analysis. RESULTS The diagnosis of episodic ataxia type 2 (EA2) was genetically confirmed in 7 subjects. Patients receiving placebo had a median monthly attack frequency of 6.50, whereas patients taking 4AP had a frequency of 1.65 (p = 0.03). Median monthly attack duration decreased from 13.65 hours with placebo to 4.45 hours with 4AP (p = 0.08). The VDADL score decreased from 6.00 to 1.50 (p = 0.02). 4AP was well-tolerated. CONCLUSIONS This controlled trial on EA2 and familial episodic ataxia with nystagmus demonstrated that 4AP decreases attack frequency and improves quality of life. LEVEL OF EVIDENCE This crossover study provides Class II evidence that 4AP decreases attack frequency and improves the patient-reported quality of life in patients with episodic ataxia and related familial ataxias.
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Affiliation(s)
- M Strupp
- Department of Neurology, Friedrich-Baur-Institute and IFB(LMU), University of Munich, Campus Grosshadern, Marchioninistr. 15, 81377 Munich, Germany.
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10
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Abstract
Episodic ataxia type 2 (EA2) is a hereditary cerebellar ataxia associated with mutations in the P/Q-type voltage-gated calcium (Ca(2+)) channels. Therapeutic approaches for treatment of EA2 are very limited. Presently, the potassium (K(+)) channel blocker 4-aminopyridine (4-AP) constitutes the most promising treatment, although its mechanism of action is not understood. Here we show that, in contrast to what is commonly believed, therapeutic concentrations of 4-AP do not increase the inhibitory drive of cerebellar Purkinje cells. Instead, 4-AP restores the severely diminished precision of pacemaking in Purkinje cells of EA2 mutant mice by prolonging the action potential and increasing the action potential afterhyperpolarization. Consistent with this mode of action, the therapeutic efficacy of 4-AP was comparable, and not additive, to chlorzoxazone, an activator of Ca(2+)-dependent K(+) channels that also restores the precision of Purkinje cell pacemaking. The likely target of 4-AP at the concentrations used are the K(v)1 family of K(+) channels, possibly the K(v)1.5 subtype. Because at higher concentrations 4-AP blocks a large array of K(+) channels and is a proconvulsant, use of selective K(v)1 channel blockers is likely to be a safer substitute for treatment of cerebellar ataxia.
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11
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Guerin AA, Feigenbaum A, Donner EJ, Yoon G. Stepwise developmental regression associated with novel CACNA1A mutation. Pediatr Neurol 2008; 39:363-4. [PMID: 18940563 DOI: 10.1016/j.pediatrneurol.2008.07.030] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/21/2008] [Revised: 07/23/2008] [Accepted: 07/28/2008] [Indexed: 11/28/2022]
Abstract
Mutations in CACNA1A were previously described in familial hemiplegic migraine, episodic ataxia type 2, and spinocerebellar ataxia type 6. We report on an 11-year-old girl with episodes of seizures, ataxia, headache, a decreased level of consciousness, and motor regression, with a background of mental retardation and mild cerebellar atrophy. Sequence analysis of the CACNA1A gene revealed a de novo Ile712Val sequence variant, which was not reported previously.
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Affiliation(s)
- Andrea A Guerin
- Department of Pediatrics, Hospital for Sick Children, University of Toronto, Toronto, Canada
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12
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Abstract
Episodic ataxia type 2 (EA 2) is a rare neurological disorder of autosomal dominant inheritance resulting from dysfunction of a voltage-gated calcium channel. It manifests with recurrent disabling attacks of imbalance, vertigo, and ataxia, and can be provoked by physical exertion or emotional stress. In the spell-free interval, patients present with central ocular motor dysfunction, mainly downbeat nystagmus. A slow progression of cerebellar signs accompanied by a slight atrophy of midline cerebellar structures is commonly observed during the course of the disease. EA 2 is caused most often by the loss of function mutations of the calcium channel gene CACNA1A, which encodes the Ca(v)2.1 subunit of the P/Q-type calcium channel and is primarily expressed in Purkinje cells. To date, more than 30 mutations have been described. Two effective treatment options have been established for EA 2: acetazolamide (ACTZ), which probably changes the intracellular pH and thereby the transmembraneous potential, and 4-aminopyridine (4-AP), a potassium channel blocker. Approximately 70% of all patients respond to treatment with ACTZ, but the effect is often only transient. In an open trial, 4-AP prevented attacks in five of six patients with EA 2, most likely by increasing the resting activity and excitability of the Purkinje cells. These findings were confirmed by experiments in animal models of EA 2. Many aspects of the pathophysiology (e.g., induction of the attacks) and treatment of EA 2 (e.g., mode of action of ACTZ and 4-AP) still remain unclear and need to be addressed in further animal and clinical studies.
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Affiliation(s)
- Michael Strupp
- Department of Neurology, University of Munich, Munich, Germany.
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13
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Walter JT, Alviña K, Womack MD, Chevez C, Khodakhah K. Decreases in the precision of Purkinje cell pacemaking cause cerebellar dysfunction and ataxia. Nat Neurosci 2006; 9:389-97. [PMID: 16474392 DOI: 10.1038/nn1648] [Citation(s) in RCA: 311] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2005] [Accepted: 01/20/2006] [Indexed: 11/08/2022]
Abstract
Episodic ataxia type-2 (EA2) is caused by mutations in P/Q-type voltage-gated calcium channels that are expressed at high densities in cerebellar Purkinje cells. Because P/Q channels support neurotransmitter release at many synapses, it is believed that ataxia is caused by impaired synaptic transmission. Here we show that in ataxic P/Q channel mutant mice, the precision of Purkinje cell pacemaking is lost such that there is a significant degradation of the synaptic information encoded in their activity. The irregular pacemaking is caused by reduced activation of calcium-activated potassium (K(Ca)) channels and was reversed by pharmacologically increasing their activity with 1-ethyl-2-benzimidazolinone (EBIO). Moreover, chronic in vivo perfusion of EBIO into the cerebellum of ataxic mice significantly improved motor performance. Our data support the hypothesis that the precision of intrinsic pacemaking in Purkinje cells is essential for motor coordination and suggest that K(Ca) channels may constitute a potential therapeutic target in EA2.
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Affiliation(s)
- Joy T Walter
- Department of Neuroscience, Albert Einstein College of Medicine, 506 Kennedy Center, 1410 Pelham Parkway South, Bronx, New York 10461, USA
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14
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Fureman BE, Hess EJ. Noradrenergic blockade prevents attacks in a model of episodic dysfunction caused by a channelopathy. Neurobiol Dis 2006; 20:227-32. [PMID: 16242631 DOI: 10.1016/j.nbd.2005.03.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2004] [Revised: 12/06/2004] [Accepted: 03/04/2005] [Indexed: 11/20/2022] Open
Abstract
Episodic neurological dysfunction often results from ion channel gene mutations. Despite knowledge of the mutations, the factors that precipitate attacks in channelopathies are not clear. In humans, mutations of the calcium channel gene CACNA1A are associated with attacks of neurological dysfunction in familial hemiplegic migraine and episodic ataxia type-2. In tottering mice, a mutation in the same gene causes attacks resembling paroxysmal dyskinesia. Stress, a trigger associated with human episodic disorders, reliably elicits attacks in tottering mice. Because noradrenergic neurotransmission is critical to the stress response and because noradrenergic hyperinnervation is observed in tottering mice, the role of norepinephrine in stress-induced attacks was investigated. Drugs that act at alpha-adrenergic receptors to block noradrenergic transmission prevented attacks. However, agents that facilitate noradrenergic neurotransmission failed to induce attacks. These results suggest that, while noradrenergic neurotransmission may be necessary for attacks, an increase in norepinephrine is not sufficient to induce attacks.
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MESH Headings
- Adrenergic Agonists/pharmacology
- Adrenergic alpha-Antagonists/pharmacology
- Animals
- Autonomic Nervous System Diseases/genetics
- Autonomic Nervous System Diseases/metabolism
- Autonomic Nervous System Diseases/physiopathology
- Brain/drug effects
- Brain/metabolism
- Brain/physiopathology
- Brain Diseases, Metabolic/drug therapy
- Brain Diseases, Metabolic/genetics
- Brain Diseases, Metabolic/physiopathology
- Calcium Channels/genetics
- Disease Models, Animal
- Female
- Ion Channels/drug effects
- Ion Channels/genetics
- Ion Channels/metabolism
- Male
- Mice
- Mice, Neurologic Mutants
- Movement Disorders/drug therapy
- Movement Disorders/physiopathology
- Movement Disorders/prevention & control
- Mutation/genetics
- Norepinephrine/antagonists & inhibitors
- Norepinephrine/metabolism
- Receptors, Adrenergic, alpha/drug effects
- Receptors, Adrenergic, alpha/metabolism
- Stress, Physiological/metabolism
- Stress, Physiological/physiopathology
- Synaptic Transmission/drug effects
- Synaptic Transmission/genetics
- Treatment Outcome
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Affiliation(s)
- Brandy E Fureman
- Department of Neurology, Johns Hopkins University, Baltimore, MD 21152, USA
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Abstract
BACKGROUND Patients with migraine are at an increased risk for white matter lesions, typically multiple, small, punctate hyperintensities in the deep or periventricular white matter, best observed on magnetic resonance imaging utilizing T2-weighted or FLAIR sequences. The underlying pathogenesis of white matter lesions in migraineurs is unknown, and the lesions are usually nonspecific and of unclear clinical significance. REVIEW SUMMARY Often the presence of white matter lesions causes uncertainty for physicians and anxiety for patients and may lead to a variety of diagnostic tests and treatments. Occasionally, white matter lesions may represent a secondary cause for headaches such as CADASIL (cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy). CADASIL is underrecognized and underdiagnosed; it should be suggested by (i) 1 or more of recurrent subcortical ischemic strokes (especially before age 60 and in the absence of vascular risk factors), migraine (especially with aura, including atypical or prolonged auras) and/or early cognitive decline or subcortical dementia; (ii) bilateral, multifocal, T2/FLAIR hyperintensities in the deep white matter and periventricular white matter with lesions involving the anterior temporal pole, external capsule, basal ganglia, and/or pons; and (iii) an autosomal-dominant family history of migraine, early-onset stroke, or dementia. The clinical spectrum of CADASIL is broad, and there is a poor genotype-phenotype correlation. In certain individuals or families, migraine may be the only clinical manifestation. CONCLUSIONS While the prevalence of nonspecific white matter lesions in migraineurs is increased, the white matter lesions may occasionally represent a secondary cause for headache such as CADASIL. Greater awareness of the unique clinical, neuroimaging, and pathologic features, as well as the availability of diagnostic genetic testing, should enhance the recognition and diagnosis of this fascinating condition.
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Affiliation(s)
- Jonathan P Gladstone
- Mayo Clinic College of Medicine, Department of Neurology, 13400 E. Shea Blvd., Scottsdale, AZ 85259, USA.
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