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Zhao T, Wang L, Chen F. Potassium channel-related epilepsy: Pathogenesis and clinical features. Epilepsia Open 2024. [PMID: 38560778 DOI: 10.1002/epi4.12934] [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: 04/25/2023] [Revised: 03/11/2024] [Accepted: 03/17/2024] [Indexed: 04/04/2024] Open
Abstract
Variants in potassium channel-related genes are one of the most important mechanisms underlying abnormal neuronal excitation and disturbances in the cellular resting membrane potential. These variants can cause different forms of epilepsy, which can seriously affect the physical and mental health of patients, especially those with refractory epilepsy or status epilepticus, which are common among pediatric patients and are potentially life-threatening. Variants in potassium ion channel-related genes have been reported in few studies; however, to our knowledge, no systematic review has been published. This study aimed to summarize the epilepsy phenotypes, functional studies, and pharmacological advances associated with different potassium channel gene variants to assist clinical practitioners and drug development teams to develop evidence-based medicine and guide research strategies. PubMed and Google Scholar were searched for relevant literature on potassium channel-related epilepsy reported in the past 5-10 years. Various common potassium ion channel gene variants can lead to heterogeneous epilepsy phenotypes, and functional effects can result from gene deletions and compound effects. Administration of select anti-seizure medications is the primary treatment for this type of epilepsy. Most patients are refractory to anti-seizure medications, and some novel anti-seizure medications have been found to improve seizures. Use of targeted drugs to correct aberrant channel function based on the type of potassium channel gene variant can be used as an evidence-based pathway to achieve precise and individualized treatment for children with epilepsy. PLAIN LANGUAGE SUMMARY: In this article, the pathogenesis and clinical characteristics of epilepsy caused by different types of potassium channel gene variants are reviewed in the light of the latest research literature at home and abroad, with the expectation of providing a certain theoretical basis for the diagnosis and treatment of children with this type of disease.
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Affiliation(s)
- Tong Zhao
- Hebei Children's Hospital, Shijiazhuang, Hebei, China
| | - Le Wang
- Hebei Children's Hospital, Shijiazhuang, Hebei, China
| | - Fang Chen
- Hebei Children's Hospital, Shijiazhuang, Hebei, China
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2
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Xie C, Kessi M, Yin F, Peng J. Roles of KCNA2 in Neurological Diseases: from Physiology to Pathology. Mol Neurobiol 2024:10.1007/s12035-024-04120-9. [PMID: 38517617 DOI: 10.1007/s12035-024-04120-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Accepted: 03/10/2024] [Indexed: 03/24/2024]
Abstract
Potassium voltage-gated channel subfamily a member 2 (Kv1.2, encoded by KCNA2) is highly expressed in the central and peripheral nervous systems. Based on the patch clamp studies, gain-of function (GOF), loss-of-function (LOF), and a mixed type (GOF/LOF) variants can cause different conditions/disorders. KCNA2-related neurological diseases include epilepsy, intellectual disability (ID), attention deficit/hyperactive disorder (ADHD), autism spectrum disorder (ASD), pain as well as autoimmune and movement disorders. Currently, the molecular mechanisms for the reported variants in causing diverse disorders are unknown. Consequently, this review brings up to date the related information regarding the structure and function of Kv1.2 channel, expression patterns, neuronal localizations, and tetramerization as well as important cell and animal models. In addition, it provides updates on human genetic variants, genotype-phenotype correlations especially highlighting the deep insight into clinical prognosis of KCNA2-related developmental and epileptic encephalopathy, mechanisms, and the potential treatment targets for all KCNA2-related neurological disorders.
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Affiliation(s)
- Changning Xie
- Department of Pediatrics, Xiangya Hospital, Central South University, Xiangya Road 87, Hunan, Changsha, 410008, China
| | - Miriam Kessi
- Department of Pediatrics, Xiangya Hospital, Central South University, Xiangya Road 87, Hunan, Changsha, 410008, China
| | - Fei Yin
- Department of Pediatrics, Xiangya Hospital, Central South University, Xiangya Road 87, Hunan, Changsha, 410008, China
| | - Jing Peng
- Department of Pediatrics, Xiangya Hospital, Central South University, Xiangya Road 87, Hunan, Changsha, 410008, China.
- Hunan Intellectual and Development Disabilities Research Center, Hunan, Changsha, 410008, China.
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Zimmern V, Minassian B. Progressive Myoclonus Epilepsy: A Scoping Review of Diagnostic, Phenotypic and Therapeutic Advances. Genes (Basel) 2024; 15:171. [PMID: 38397161 PMCID: PMC10888128 DOI: 10.3390/genes15020171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2024] [Revised: 01/23/2024] [Accepted: 01/26/2024] [Indexed: 02/25/2024] Open
Abstract
The progressive myoclonus epilepsies (PME) are a diverse group of disorders that feature both myoclonus and seizures that worsen gradually over a variable timeframe. While each of the disorders is individually rare, they collectively make up a non-trivial portion of the complex epilepsy and myoclonus cases that are seen in tertiary care centers. The last decade has seen substantial progress in our understanding of the pathophysiology, diagnosis, prognosis, and, in select disorders, therapies of these diseases. In this scoping review, we examine English language publications from the past decade that address diagnostic, phenotypic, and therapeutic advances in all PMEs. We then highlight the major lessons that have been learned and point out avenues for future investigation that seem promising.
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Affiliation(s)
- Vincent Zimmern
- Division of Child Neurology, University of Texas Southwestern, Dallas, TX 75390, USA;
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Shakeel K, Olamendi-Portugal T, Naseem MU, Becerril B, Zamudio FZ, Delgado-Prudencio G, Possani LD, Panyi G. Of Seven New K + Channel Inhibitor Peptides of Centruroides bonito, α-KTx 2.24 Has a Picomolar Affinity for Kv1.2. Toxins (Basel) 2023; 15:506. [PMID: 37624263 PMCID: PMC10467108 DOI: 10.3390/toxins15080506] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2023] [Revised: 08/07/2023] [Accepted: 08/11/2023] [Indexed: 08/26/2023] Open
Abstract
Seven new peptides denominated CboK1 to CboK7 were isolated from the venom of the Mexican scorpion Centruroides bonito and their primary structures were determined. The molecular weights ranged between 3760.4 Da and 4357.9 Da, containing 32 to 39 amino acid residues with three putative disulfide bridges. The comparison of amino acid sequences with known potassium scorpion toxins (KTx) and phylogenetic analysis revealed that CboK1 (α-KTx 10.5) and CboK2 (α-KTx 10.6) belong to the α-KTx 10.x subfamily, whereas CboK3 (α-KTx 2.22), CboK4 (α-KTx 2.23), CboK6 (α-KTx 2.21), and CboK7 (α-KTx 2.24) bear > 95% amino acid similarity with members of the α-KTx 2.x subfamily, and CboK5 is identical to Ce3 toxin (α-KTx 2.10). Electrophysiological assays demonstrated that except CboK1, all six other peptides blocked the Kv1.2 channel with Kd values in the picomolar range (24-763 pM) and inhibited the Kv1.3 channel with comparatively less potency (Kd values between 20-171 nM). CboK3 and CboK4 inhibited less than 10% and CboK7 inhibited about 42% of Kv1.1 currents at 100 nM concentration. Among all, CboK7 showed out-standing affinity for Kv1.2 (Kd = 24 pM), as well as high selectivity over Kv1.3 (850-fold) and Kv1.1 (~6000-fold). These characteristics of CboK7 may provide a framework for developing tools to treat Kv1.2-related channelopathies.
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Affiliation(s)
- Kashmala Shakeel
- Department of Biophysics and Cell Biology, Faculty of Medicine, Research Center for Molecular Medicine, University of Debrecen, Egyetem ter. 1, 4032 Debrecen, Hungary; (K.S.); (M.U.N.)
| | - Timoteo Olamendi-Portugal
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnologia, Universidad Nacional Autónoma de México, Av. Universidad 2001, Cuernavaca 62210, Mexico; (T.O.-P.); (B.B.); (F.Z.Z.); (G.D.-P.)
| | - Muhammad Umair Naseem
- Department of Biophysics and Cell Biology, Faculty of Medicine, Research Center for Molecular Medicine, University of Debrecen, Egyetem ter. 1, 4032 Debrecen, Hungary; (K.S.); (M.U.N.)
| | - Baltazar Becerril
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnologia, Universidad Nacional Autónoma de México, Av. Universidad 2001, Cuernavaca 62210, Mexico; (T.O.-P.); (B.B.); (F.Z.Z.); (G.D.-P.)
| | - Fernando Z. Zamudio
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnologia, Universidad Nacional Autónoma de México, Av. Universidad 2001, Cuernavaca 62210, Mexico; (T.O.-P.); (B.B.); (F.Z.Z.); (G.D.-P.)
| | - Gustavo Delgado-Prudencio
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnologia, Universidad Nacional Autónoma de México, Av. Universidad 2001, Cuernavaca 62210, Mexico; (T.O.-P.); (B.B.); (F.Z.Z.); (G.D.-P.)
| | - Lourival Domingos Possani
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnologia, Universidad Nacional Autónoma de México, Av. Universidad 2001, Cuernavaca 62210, Mexico; (T.O.-P.); (B.B.); (F.Z.Z.); (G.D.-P.)
| | - Gyorgy Panyi
- Department of Biophysics and Cell Biology, Faculty of Medicine, Research Center for Molecular Medicine, University of Debrecen, Egyetem ter. 1, 4032 Debrecen, Hungary; (K.S.); (M.U.N.)
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Wang H, Zhu Y, Cao D, Chen H, Ding X, Zeng Q, Zou H, Liao J. Successful medical treatment of west syndrome with a KCNA2 variant: a case report. ACTA EPILEPTOLOGICA 2022. [DOI: 10.1186/s42494-021-00069-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Abstract
Background
West syndrome is a devastating disorder characterized by a triad of epileptic spasms, abnormal electroencephalography (EEG), and developmental arrest or psychomotor delay. In addition to early diagnosis, knowing the etiology of the condition is also important for its treatment. Among various etiologies, the genetic factors, especially mutations of ion channel genes, are very common and strongly linked to West syndrome.
Case presentation
A boy who had epileptic spasms from the age of 4 months was diagnosed with West syndrome based on the clinical manifestation and EEG results in Shenzhen Children’s Hospital in June 2019. Trios whole-exome sequencing (WES) test and protein structural model prediction were performed. We also reviewed the clinical and genetic features of this syndrome and the mechanisms of action of topiramate (TPM) by literature search in databases of Online Mendelian Inheritance in Man, Clinical Genome Resource, PubMed, Chinese National Knowledge Infrastructure and Wanfang database using keywords “KCNA2” “West syndrome” and “Topiramate” by December 2020. The relationship between the effect of TPM and the pathogenesis of the KCNA2 variant was also assessed. The WES test revealed c.244C > T/p. Arg82Cys varaint of KCNA2 (NM_004974.3) in this patient, and Sanger sequencing identified this was a de novo mutation. As far as we know, this is the first report of the c.244C > T/p. Arg82Cys variant in KCNA2, which was likely a pathogenic mutation. The seizures were successfully controlled for 10 months by TPM after failure of sodium valproate, large doses of vitamin B6, and adrenocorticotropic hormone. We speculate that the therapeutic effect of TPM in this patient is partially due to the inhibition of carbonic anhydrase.
Conclusions
Mutations in the KCNA2 gene should be considered for patients with West syndrome. The TPM treatment is probably effective for KCNA2-associated disorders.
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Perilli L, Mastromoro G, Murciano M, Amedeo I, Avenoso F, Pizzuti A, Guido CA, Spalice A. Myoclonic Epilepsy: Case Report of a Mild Phenotype in a Pediatric Patient Expanding Clinical Spectrum of KCNA2 Pathogenic Variants. Front Neurol 2022; 12:806516. [PMID: 35178022 PMCID: PMC8844549 DOI: 10.3389/fneur.2021.806516] [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: 10/31/2021] [Accepted: 12/31/2021] [Indexed: 11/24/2022] Open
Abstract
We report on the rare case of a male toddler presenting with myoclonic epilepsy characterized by daily episodes of upward movements of the eyebrows, and myoclonic jerks of both head and upper limbs. In addition, the child showed speech delay, tremors, and lack of motor coordination. Next Generation Sequencing analysis (NGS) performed in trio revealed in the proband the c.889C>T de novo missense variant in the KCNA2 gene in heterozygous state. This is the first case of myoclonic epilepsy in a toddler due to a c.889C>T KCNA2 missense variant. The patient was treated with valproic acid and ethosuximide with a good clinical response. At 6 years old, follow-up revealed that the proband was seizure-free with tremors and clumsiness in movements. According to the literature, this case supports the correlation between myoclonic epilepsy and KCNA2 alterations. This evidence suggests that performing genomic testing including the KCNA2 gene in preschool patients affected by myoclonic epilepsy, especially when associated with delayed neurodevelopment. Our goal is to expand the phenotypical spectrum of this rare condition and adding clinical features following a genotype-first approach.
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Affiliation(s)
- Lorenzo Perilli
- Department of Mother and Child and Urological Sciences, Sapienza University of Rome, Rome, Italy
| | - Gioia Mastromoro
- Faculty of Medicine and Dentistry, Department of Experimental Medicine, Sapienza University of Rome, Rome, Italy
| | - Manuel Murciano
- Department of Mother and Child and Urological Sciences, Sapienza University of Rome, Rome, Italy.,Department of Emergency Pediatrics, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - Ilaria Amedeo
- Department of Mother and Child and Urological Sciences, Sapienza University of Rome, Rome, Italy
| | - Federica Avenoso
- Department of Mother and Child and Urological Sciences, Sapienza University of Rome, Rome, Italy
| | - Antonio Pizzuti
- Faculty of Medicine and Dentistry, Department of Experimental Medicine, Sapienza University of Rome, Rome, Italy
| | - Cristiana Alessia Guido
- Department of Mother and Child and Urological Sciences, Sapienza University of Rome, Rome, Italy
| | - Alberto Spalice
- Department of Mother and Child and Urological Sciences, Sapienza University of Rome, Rome, Italy
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McGinn RJ, Von Stein EL, Summers Stromberg JE, Li Y. Precision medicine in epilepsy. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2022; 190:147-188. [DOI: 10.1016/bs.pmbts.2022.04.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Courage C, Oliver KL, Park EJ, Cameron JM, Grabińska KA, Muona M, Canafoglia L, Gambardella A, Said E, Afawi Z, Baykan B, Brandt C, di Bonaventura C, Chew HB, Criscuolo C, Dibbens LM, Castellotti B, Riguzzi P, Labate A, Filla A, Giallonardo AT, Berecki G, Jackson CB, Joensuu T, Damiano JA, Kivity S, Korczyn A, Palotie A, Striano P, Uccellini D, Giuliano L, Andermann E, Scheffer IE, Michelucci R, Bahlo M, Franceschetti S, Sessa WC, Berkovic SF, Lehesjoki AE. Progressive myoclonus epilepsies-Residual unsolved cases have marked genetic heterogeneity including dolichol-dependent protein glycosylation pathway genes. Am J Hum Genet 2021; 108:722-738. [PMID: 33798445 DOI: 10.1016/j.ajhg.2021.03.013] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 03/05/2021] [Indexed: 02/04/2023] Open
Abstract
Progressive myoclonus epilepsies (PMEs) comprise a group of clinically and genetically heterogeneous rare diseases. Over 70% of PME cases can now be molecularly solved. Known PME genes encode a variety of proteins, many involved in lysosomal and endosomal function. We performed whole-exome sequencing (WES) in 84 (78 unrelated) unsolved PME-affected individuals, with or without additional family members, to discover novel causes. We identified likely disease-causing variants in 24 out of 78 (31%) unrelated individuals, despite previous genetic analyses. The diagnostic yield was significantly higher for individuals studied as trios or families (14/28) versus singletons (10/50) (OR = 3.9, p value = 0.01, Fisher's exact test). The 24 likely solved cases of PME involved 18 genes. First, we found and functionally validated five heterozygous variants in NUS1 and DHDDS and a homozygous variant in ALG10, with no previous disease associations. All three genes are involved in dolichol-dependent protein glycosylation, a pathway not previously implicated in PME. Second, we independently validate SEMA6B as a dominant PME gene in two unrelated individuals. Third, in five families, we identified variants in established PME genes; three with intronic or copy-number changes (CLN6, GBA, NEU1) and two very rare causes (ASAH1, CERS1). Fourth, we found a group of genes usually associated with developmental and epileptic encephalopathies, but here, remarkably, presenting as PME, with or without prior developmental delay. Our systematic analysis of these cases suggests that the small residuum of unsolved cases will most likely be a collection of very rare, genetically heterogeneous etiologies.
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Affiliation(s)
- Carolina Courage
- Folkhälsan Research Center, Helsinki 00290, Finland; Department of Medical and Clinical Genetics, Medicum, University of Helsinki, Helsinki 00290, Finland
| | - Karen L Oliver
- Epilepsy Research Centre, Department of Medicine, University of Melbourne, Austin Health, Heidelberg 3084, Victoria, Australia; Population Health and Immunity Division, the Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia; Department of Medical Biology, the University of Melbourne, Melbourne, VIC 3010, Australia
| | - Eon Joo Park
- Department of Pharmacology and Vascular Biology and Therapeutics Program, Yale University School of Medicine, 10 Amistad Street, New Haven, CT 06520, USA
| | - Jillian M Cameron
- Epilepsy Research Centre, Department of Medicine, University of Melbourne, Austin Health, Heidelberg 3084, Victoria, Australia
| | - Kariona A Grabińska
- Department of Pharmacology and Vascular Biology and Therapeutics Program, Yale University School of Medicine, 10 Amistad Street, New Haven, CT 06520, USA
| | - Mikko Muona
- Folkhälsan Research Center, Helsinki 00290, Finland; Blueprint Genetics, Espoo 02150, Finland
| | - Laura Canafoglia
- Neurophysiopathology, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan 20133, Italy
| | | | - Edith Said
- Section of Medical Genetics, Mater dei Hospital, Msida MSD2090, Malta; Department of Anatomy and Cell Biology, University of Malta, Msida MSD2090, Malta
| | - Zaid Afawi
- Center for Neuroscience, Ben-Gurion University of the Negev, Be'er Sheva 8410402, Israel
| | - Betul Baykan
- Departments of Neurology and Clinical Neurophysiology, Istanbul Faculty of Medicine, Istanbul University, Istanbul 34452, Turkey
| | | | - Carlo di Bonaventura
- Department of Human Neurosciences, Sapienza University of Rome, Viale dell'Università, 30, 00185 Rome, Italy
| | - Hui Bein Chew
- Genetics Department, Kuala Lumpur Hospital, Ministry of Health Malaysia, Jalan Pahang, 50586 Kuala Lumpur, Malaysia
| | - Chiara Criscuolo
- Department of Neuroscience, Reproductive, and Odontostomatological Sciences, University of Naples Federico II, Naples 80138, Italy
| | - Leanne M Dibbens
- Epilepsy Research Group, Australian Centre for Precision Health, UniSA Clinical and Health Sciences, University of South Australia, Adelaide, SA 5000, Australia
| | - Barbara Castellotti
- Unit of Genetics of Neurodegenerative and Metabolic Diseases, IRCCS Istituto Neurologico Carlo Besta Milan 20133, Italy
| | - Patrizia Riguzzi
- IRCCS Istituto delle Scienze Neurologiche di Bologna, Unit of Neurology, Bellaria Hospital, Bologna 40139, Italy
| | - Angelo Labate
- Institute of Neurology, University Magna Græcia, Catanzaro 88100, Italy
| | - Alessandro Filla
- Department of Neuroscience, Reproductive, and Odontostomatological Sciences, University of Naples Federico II, Naples 80138, Italy
| | - Anna T Giallonardo
- Neurology Unit, Human Neurosciences Department, Sapienza University, Rome 00185, Italy
| | - Geza Berecki
- Ion Channels and Disease Group, Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC 3052, Australia
| | - Christopher B Jackson
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, 00290 Helsinki, Finland
| | | | - John A Damiano
- Epilepsy Research Centre, Department of Medicine, University of Melbourne, Austin Health, Heidelberg 3084, Victoria, Australia
| | - Sara Kivity
- Epilepsy Unit, Schneider Children's Medical Center of Israel, Petah Tiqvah 4922297, Israel
| | - Amos Korczyn
- Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 60198, Israel
| | - Aarno Palotie
- Institute for Molecular Medicine Finland (FIMM), HiLIFE, University of Helsinki, Helsinki 00290, Finland; Analytic and Translational Genetics Unit, Department of Medicine, Department of Neurology and Department of Psychiatry Massachusetts General Hospital, Boston, MA 02114, USA; The Stanley Center for Psychiatric Research and Program in Medical and Population Genetics, The Broad Institute of MIT and Harvard, Cambridge, Boston, MA 02142, USA
| | - Pasquale Striano
- Pediatric Neurology and Muscular Diseases Unit, IRCCS Istituto "G. Gaslini," Genova 16147, Italy
| | - Davide Uccellini
- Neurology - Neurophysiology Unit, ASST dei Sette Laghi, Galmarini Tradate Hospital, Tradate 21049, Italy
| | - Loretta Giuliano
- Dipartimento "G.F. Ingrassia," Università degli Studi di Catania, Catania 95131, Italy
| | - Eva Andermann
- Neurogenetics Unit and Epilepsy Research Group, Montreal Neurological Hospital and Institute, Montreal, QC H3A 2B4, Canada; Departments of Neurology & Neurosurgery and Human Genetics, McGill University, Montreal, QC H3A 0G4, Canada
| | - Ingrid E Scheffer
- Epilepsy Research Centre, Department of Medicine, University of Melbourne, Austin Health, Heidelberg 3084, Victoria, Australia; Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, VIC 3052, Australia; Department of Paediatrics, The University of Melbourne, Royal Children's Hospital, Parkville, VIC 3052, Australia; The Florey Institute, Parkville, VIC 3052, Australia
| | - Roberto Michelucci
- IRCCS Istituto delle Scienze Neurologiche di Bologna, Unit of Neurology, Bellaria Hospital, Bologna 40139, Italy
| | - Melanie Bahlo
- Population Health and Immunity Division, the Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia; Department of Medical Biology, the University of Melbourne, Melbourne, VIC 3010, Australia
| | - Silvana Franceschetti
- Neurophysiopathology, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan 20133, Italy
| | - William C Sessa
- Department of Pharmacology and Vascular Biology and Therapeutics Program, Yale University School of Medicine, 10 Amistad Street, New Haven, CT 06520, USA
| | - Samuel F Berkovic
- Epilepsy Research Centre, Department of Medicine, University of Melbourne, Austin Health, Heidelberg 3084, Victoria, Australia.
| | - Anna-Elina Lehesjoki
- Folkhälsan Research Center, Helsinki 00290, Finland; Department of Medical and Clinical Genetics, Medicum, University of Helsinki, Helsinki 00290, Finland.
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Refining Genotypes and Phenotypes in KCNA2-Related Neurological Disorders. Int J Mol Sci 2021; 22:ijms22062824. [PMID: 33802230 PMCID: PMC7999221 DOI: 10.3390/ijms22062824] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2021] [Revised: 03/03/2021] [Accepted: 03/04/2021] [Indexed: 02/06/2023] Open
Abstract
Pathogenic variants in KCNA2, encoding for the voltage-gated potassium channel Kv1.2, have been identified as the cause for an evolving spectrum of neurological disorders. Affected individuals show early-onset developmental and epileptic encephalopathy, intellectual disability, and movement disorders resulting from cerebellar dysfunction. In addition, individuals with a milder course of epilepsy, complicated hereditary spastic paraplegia, and episodic ataxia have been reported. By analyzing phenotypic, functional, and genetic data from published reports and novel cases, we refine and further delineate phenotypic as well as functional subgroups of KCNA2-associated disorders. Carriers of variants, leading to complex and mixed channel dysfunction that are associated with a gain- and loss-of-potassium conductance, more often show early developmental abnormalities and an earlier onset of epilepsy compared to individuals with variants resulting in loss- or gain-of-function. We describe seven additional individuals harboring three known and the novel KCNA2 variants p.(Pro407Ala) and p.(Tyr417Cys). The location of variants reported here highlights the importance of the proline(405)–valine(406)–proline(407) (PVP) motif in transmembrane domain S6 as a mutational hotspot. A novel case of self-limited infantile seizures suggests a continuous clinical spectrum of KCNA2-related disorders. Our study provides further insights into the clinical spectrum, genotype–phenotype correlation, variability, and predicted functional impact of KCNA2 variants.
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Gong P, Jiao X, Zhang Y, Yang Z. Complex Mosaicism of Two Distinct Mutations in a Female Patient With KCNA2-Related Encephalopathy: A Case Report. Front Genet 2020; 11:911. [PMID: 32903602 PMCID: PMC7438874 DOI: 10.3389/fgene.2020.00911] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Accepted: 07/22/2020] [Indexed: 12/29/2022] Open
Abstract
KCNA2 gene mutations were described to cause a new molecular entity within the developmental and epileptic or epileptic encephalopathies. Here, we firstly reported a patient with an unusual mosaicism for KCNA2, presenting two distinct mosaic missense mutations at the same loci. Clinical trio-based whole-exome sequencing using next-generation sequencing (NGS) revealed two novel mutations in KCNA2: c.1225A > T [p.(Ile409Phe)] and c.1225A > C [p.(Ile409Leu)]. Both missense mutations were in mosaic status and Sanger sequencing confirmed them as de novo. The affected 5-year-old girl presented as seizures with fever sensitivity, and mild cognitive and behavioral disorders. EEG showed focal centrotemporal epileptiform discharges accompanied by nocturnal focal seizures at the age of slightly older than 5 years, more likely carrying a loss-of-function mutation of KCNA2-related phenotype. Further NGS with a mean coverage of 6950 × showed 26% (mosaic mutation reads/total reads) of the c.1225A > T mutation and 23% of the c.1225A > C mutation. The sum of their allele fractions was close to 50%, approximately equal to a heterozygous variant. The patient had no seizures for 8 months on combination of levetiracetam (18.75 mg/kg/d) and valproate (20 mg/kg/d) till the last follow-up at the age of 5 years and 11 months. Our findings highlighted the two mosaic mutations responsible for the pathogenesis of KCNA2-related encephalopathy. The patient expanded the mutational spectrum of KCNA2-related encephalopathy and provided new insight into the complex genetic disorder.
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Affiliation(s)
- Pan Gong
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Xianru Jiao
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Yuehua Zhang
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Zhixian Yang
- Department of Pediatrics, Peking University First Hospital, Beijing, China
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Liu YD, Ma MY, Hu XB, Yan H, Zhang YK, Yang HX, Feng JH, Wang L, Zhang H, Zhang B, Li QB, Zhang JC, Kong QX. Brain Proteomic Profiling in Intractable Epilepsy Caused by TSC1 Truncating Mutations: A Small Sample Study. Front Neurol 2020; 11:475. [PMID: 32655475 PMCID: PMC7326032 DOI: 10.3389/fneur.2020.00475] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Accepted: 04/30/2020] [Indexed: 01/01/2023] Open
Abstract
Tuberous sclerosis complex (TSC) is a genetic disease characterized by seizures, mental deficiency, and abnormalities of the skin, brain, kidney, heart, and lungs. TSC is inherited in an autosomal dominant manner and is caused by variations in either the TSC1 or TSC2 gene. TSC-related epilepsy (TRE) is the most prevalent and challenging clinical feature of TSC, and more than half of the patients have refractory epilepsy. In clinical practice, we found several patients of intractable epilepsy caused by TSC1 truncating mutations. To study the changes of protein expression in the brain, three cases of diseased brain tissue with TSC1 truncating mutation resected in intractable epilepsy operations and three cases of control brain tissue resected in craniocerebral trauma operations were collected to perform protein spectrum detection, and then the data-independent acquisition (DIA) workflow was used to analyze differentially expressed proteins. As a result, there were 55 up- and 55 down-regulated proteins found in the damaged brain tissue with TSC1 mutation compared to the control. Further bioinformatics analysis revealed that the differentially expressed proteins were mainly concentrated in the synaptic membrane between the patients with TSC and the control. Additionally, TSC1 truncating mutations may affect the pathway of amino acid metabolism. Our study provides a new idea to explore the brain damage mechanism caused by TSC1 mutations.
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Affiliation(s)
- Yi-Dan Liu
- Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Meng-Yu Ma
- Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Xi-Bin Hu
- Department of Imaging, Affiliated Hospital of Jining Medical University, Jining, China
| | - Huan Yan
- Department of Neurology, Affiliated Hospital of Jining Medical University, Jining, China
| | - Yan-Ke Zhang
- Department of Neurology, Affiliated Hospital of Jining Medical University, Jining, China
| | - Hao-Xiang Yang
- Clinical Medical College, Jining Medical University, Jining, China
| | - Jing-Hui Feng
- Clinical Medical College, Jining Medical University, Jining, China
| | - Lin Wang
- Department of Neurology, Affiliated Hospital of Jining Medical University, Jining, China
| | - Hao Zhang
- Department of Neurosurgery, Affiliated Hospital of Jining Medical University, Jining, China
| | - Bin Zhang
- Department of Neurosurgery, Affiliated Hospital of Jining Medical University, Jining, China
| | - Qiu-Bo Li
- Department of Pediatrics, Affiliated Hospital of Jining Medical University, Jining, China
| | - Jun-Chen Zhang
- Department of Neurosurgery, Affiliated Hospital of Jining Medical University, Jining, China
| | - Qing-Xia Kong
- Department of Neurology, Affiliated Hospital of Jining Medical University, Jining, China.,Institute of Epilepsy, Jining Medical University, Jining, China
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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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Allen NM, Weckhuysen S, Gorman K, King MD, Lerche H. Genetic potassium channel-associated epilepsies: Clinical review of the K v family. Eur J Paediatr Neurol 2020; 24:105-116. [PMID: 31932120 DOI: 10.1016/j.ejpn.2019.12.002] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Accepted: 12/06/2019] [Indexed: 12/22/2022]
Abstract
Next-generation sequencing has enhanced discovery of many disease-associated genes in previously unexplained epilepsies, mainly in developmental and epileptic encephalopathies and familial epilepsies. We now classify these disorders according to the underlying molecular pathways, which encompass a diverse array of cellular and sub-cellular compartments/signalling processes including voltage-gated ion-channel defects. With the aim to develop and increase the use of precision medicine therapies, understanding the pathogenic mechanisms and consequences of disease-causing variants has gained major relevance in clinical care. The super-family of voltage-gated potassium channels is the largest and most diverse family among the ion channels, encompassing approximately 80 genes. Key potassium channelopathies include those affecting the KV, KCa and Kir families, a significant proportion of which have been implicated in neurological disease. As for other ion channel disorders, different pathogenic variants within any individual voltage-gated potassium channel gene tend to affect channel protein function differently, causing heterogeneous clinical phenotypes. The focus of this review is to summarise recent clinical developments regarding the key voltage-gated potassium (KV) family-related epilepsies, which now encompasses approximately 12 established disease-associated genes, from the KCNA-, KCNB-, KCNC-, KCND-, KCNV-, KCNQ- and KCNH-subfamilies.
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Affiliation(s)
- Nicholas M Allen
- Department of Paediatrics, National University of Ireland, Galway, Ireland; Department of Paediatrics (Neurology), Galway University Hospital, Ireland; Regenerative Medicine Institute (REMEDI), National University of Ireland, Galway, Ireland.
| | - Sarah Weckhuysen
- Neurogenetics Group, Center for Molecular Neurology, VIB-University of Antwerp, Antwerp, Belgium; Department of Neurology, University Hospital Antwerp, Antwerp, Belgium
| | - Kathleen Gorman
- Department of Paediatric Neurology & Clinical Neurophysiology, Children's Health Ireland at Temple Street, Dublin 1, Ireland; University College Dublin School of Medicine and Medical Science, University College, Dublin, Ireland
| | - Mary D King
- Department of Paediatric Neurology & Clinical Neurophysiology, Children's Health Ireland at Temple Street, Dublin 1, Ireland; University College Dublin School of Medicine and Medical Science, University College, Dublin, Ireland
| | - Holger Lerche
- Department of Neurology and Epileptology, Hertie Institute of Clinical Brain Research, University of Tubingen, Germany
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