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Yu W, Hill SF, Xenakis JG, Pardo-Manuel de Villena F, Wagnon JL, Meisler MH. Gabra2 is a genetic modifier of Scn8a encephalopathy in the mouse. Epilepsia 2020; 61:2847-2856. [PMID: 33140451 PMCID: PMC7756374 DOI: 10.1111/epi.16741] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 10/05/2020] [Accepted: 10/06/2020] [Indexed: 12/23/2022]
Abstract
Objective SCN8A encephalopathy is a developmental epileptic encephalopathy typically caused by de novo gain‐of‐function mutations in Nav1.6. Severely affected individuals exhibit refractory seizures, developmental delay, cognitive disabilities, movement disorders, and elevated risk of sudden death. Patients with the identical SCN8A variant can differ in clinical course, suggesting a role for modifier genes in determining disease severity. The identification of genetic modifiers contributes to understanding disease pathogenesis and suggesting therapeutic interventions. Methods We generated F1 and F2 crosses between inbred mouse strains and mice carrying the human pathogenic variants SCN8A‐R1872W and SCN8A‐N1768D. Quantitative trait locus (QTL) analysis of seizure‐related phenotypes was used for chromosomal mapping of modifier loci. Results In an F2 cross between strain SJL/J and C57BL/6J mice carrying the patient mutation R1872W, we identified a major QTL on chromosome 5 containing the Gabra2 gene. Strain C57BL/6J carries a splice site mutation that reduces expression of Gabra2, encoding the α2 subunit of the aminobutyric acid type A receptor. The protective wild‐type allele of Gabra2 from strain SJL/J delays the age at seizure onset and extends life span of the Scn8a mutant mice. Additional Scn8a modifiers were observed in the F2 cross and in an F1 cross with strain C3HeB/FeJ. Significance These studies demonstrate that the SJL/J strain carries multiple modifiers with protective effects against seizures induced by gain‐of‐function mutations in Scn8a. Homozygosity for the hypomorphic variant of Gabra2 in strain C57BL/6J is associated with early seizure onset and short life span. GABRA2 is a potential therapeutic target for SCN8A encephalopathy.
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Affiliation(s)
- Wenxi Yu
- Department of Human Genetics, University of Michigan, Ann Arbor, MI, USA
| | - Sophie F Hill
- Department of Human Genetics, University of Michigan, Ann Arbor, MI, USA.,Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI, USA
| | - James G Xenakis
- Department of Genetics, University of North Carolina, Chapel Hill, NC, USA
| | | | - Jacy L Wagnon
- Department of Human Genetics, University of Michigan, Ann Arbor, MI, USA
| | - Miriam H Meisler
- Department of Human Genetics, University of Michigan, Ann Arbor, MI, USA.,Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI, USA
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2
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Menezes LFS, Sabiá Júnior EF, Tibery DV, Carneiro LDA, Schwartz EF. Epilepsy-Related Voltage-Gated Sodium Channelopathies: A Review. Front Pharmacol 2020; 11:1276. [PMID: 33013363 PMCID: PMC7461817 DOI: 10.3389/fphar.2020.01276] [Citation(s) in RCA: 61] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Accepted: 07/31/2020] [Indexed: 12/29/2022] Open
Abstract
Epilepsy is a disease characterized by abnormal brain activity and a predisposition to generate epileptic seizures, leading to neurobiological, cognitive, psychological, social, and economic impacts for the patient. There are several known causes for epilepsy; one of them is the malfunction of ion channels, resulting from mutations. Voltage-gated sodium channels (NaV) play an essential role in the generation and propagation of action potential, and malfunction caused by mutations can induce irregular neuronal activity. That said, several genetic variations in NaV channels have been described and associated with epilepsy. These mutations can affect channel kinetics, modifying channel activation, inactivation, recovery from inactivation, and/or the current window. Among the NaV subtypes related to epilepsy, NaV1.1 is doubtless the most relevant, with more than 1500 mutations described. Truncation and missense mutations are the most observed alterations. In addition, several studies have already related mutated NaV channels with the electrophysiological functioning of the channel, aiming to correlate with the epilepsy phenotype. The present review provides an overview of studies on epilepsy-associated mutated human NaV1.1, NaV1.2, NaV1.3, NaV1.6, and NaV1.7.
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Affiliation(s)
- Luis Felipe Santos Menezes
- Laboratório de Neurofarmacologia, Departamento de Ciências Fisiológicas, Universidade de Brasília, Brasília, Brazil
| | - Elias Ferreira Sabiá Júnior
- Laboratório de Neurofarmacologia, Departamento de Ciências Fisiológicas, Universidade de Brasília, Brasília, Brazil
| | - Diogo Vieira Tibery
- Laboratório de Neurofarmacologia, Departamento de Ciências Fisiológicas, Universidade de Brasília, Brasília, Brazil
| | - Lilian Dos Anjos Carneiro
- Faculdade de Medicina, Centro Universitário Euro Americano, Brasília, Brazil.,Faculdade de Medicina, Centro Universitário do Planalto Central, Brasília, Brazil
| | - Elisabeth Ferroni Schwartz
- Laboratório de Neurofarmacologia, Departamento de Ciências Fisiológicas, Universidade de Brasília, Brasília, Brazil
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3
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Fatema K, Rahman MM, Faruk O. SCN8A Mutation in Infantile Epileptic Encephalopathy: Report of Two Cases. J Epilepsy Res 2020; 9:147-151. [PMID: 32509551 PMCID: PMC7251340 DOI: 10.14581/jer.19017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Revised: 10/21/2019] [Accepted: 01/09/2020] [Indexed: 12/03/2022] Open
Abstract
Early infantile epileptic encephalopathy type 13 is a severe form of epilepsy caused by mutations in the sodium channel 8 alpha (SCN8A) gene. This gene encodes the neuronal voltage-gated sodium channel which plays vital role in neuronal excitability. Here we present two cases with SCN8A encephalopathy. Both cases had mutation in p.Arg1872Gin the SCN8A gene, which was detected by targeted next generation sequencing. Case 1 was a 14-month old boy, who had a normal birth history with normal development up to 6 months and then developed repeated generalized seizure, which was nonresponsive to multiple antiepileptic drugs. He also had neuroregression and dystonia. His electroencephalogram (EEG) showed progressive background abnormality with burst suppression pattern. His metabolic panel was normal and had partial response to carbamazepine. The second case was for an 11-month old boy with the onset of seizure at the age of 7 months. Seizure was generalized, resistant to multiple antiepileptic drugs. He had developmental delay from beginning, no movement disorder. EEG showed focal discharge from left temporal and occipital region. He showed partial response to oxcarbazepine. Our cases had similarities with the previously reported cases. The detailed discussion of our cases would contribute to early detection and targeted treatment of SCN8A encephalopathy. This also gives special emphasis on a genetic test in infants with intractable epilepsy, movement disorder and developmental delay.
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Affiliation(s)
- Kanij Fatema
- Department of Pediatric Neurology, Bangabandhu Sheikh Mujib Medical University, Dhaka, Bangladesh
| | - Md Mizanur Rahman
- Department of Pediatric Neurology, Bangabandhu Sheikh Mujib Medical University, Dhaka, Bangladesh
| | - Omar Faruk
- Department of Pediatric Neurology, Bangabandhu Sheikh Mujib Medical University, Dhaka, Bangladesh
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4
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Ma X, Yang F, Hua Z. Genetic diagnosis of neonatal-onset seizures. Genes Dis 2019; 6:441-447. [PMID: 31832524 PMCID: PMC6888710 DOI: 10.1016/j.gendis.2019.02.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Accepted: 02/02/2019] [Indexed: 12/28/2022] Open
Abstract
Many seizures in neonates are due to early-onset epilepsy, which is often difficult to diagnose, especially to explore the causes. Recently, the development of next-generation sequencing (NGS) has led to the discovery of a large number of genes involved in epilepsy. This may improve prompt detection of early-onset epilepsy in neonates. This study aimed at analyzing the genotype-phenotype correlations in neonates with seizures in a bid to improve the understanding of genetic diagnosis of early-onset epilepsy. Clinical features and prognosis of 15 children who underwent genetic testing having had unexplained seizures from February 2016 to May 2018 in Children's Hospital of Chongqing Medical University were analyzed retrospectively. The salient findings were: poor response to stimulus and abnormal electroencephalogram (EEG) in the initial period were observed in the group with concomitant genetic abnormalities. Despite the recent progress in genetic technology, molecular diagnosis for neonatal-onset epilepsy can be challenging due to genetic and phenotypic heterogeneities. However, some genotypes are associated with specific clinical manifestations and EEG patterns. Therefore, in-depth understanding of genotype-phenotype correlations would be useful to clinicians managing neonates with early-onset seizures.
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Affiliation(s)
- Xueling Ma
- The Department of Neonatology, Children's Hospital of Chongqing Medical University, Chongqing, 400014, China
- Ministry of Education Key Laboratory of Child Development and Disorders, Chongqing, 400014, China
- National Demonstration Base of Standardized Training Base for Resident Physicians, Chongqing, 400014, China
| | - Fengzhu Yang
- The Department of Neonatology, Children's Hospital of Chongqing Medical University, Chongqing, 400014, China
- Ministry of Education Key Laboratory of Child Development and Disorders, Chongqing, 400014, China
- National Demonstration Base of Standardized Training Base for Resident Physicians, Chongqing, 400014, China
| | - Ziyu Hua
- The Department of Neonatology, Children's Hospital of Chongqing Medical University, Chongqing, 400014, China
- Ministry of Education Key Laboratory of Child Development and Disorders, Chongqing, 400014, China
- Chongqing International Science and Technology Cooperation Center for Child Development and Disorders, Chongqing, 400014, China
- Chongqing Key Laboratory of Child Infection and Immunity, Chongqing, 400014, China
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5
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Bunton-Stasyshyn RKA, Wagnon JL, Wengert ER, Barker BS, Faulkner A, Wagley PK, Bhatia K, Jones JM, Maniaci MR, Parent JM, Goodkin HP, Patel MK, Meisler MH. Prominent role of forebrain excitatory neurons in SCN8A encephalopathy. Brain 2019; 142:362-375. [PMID: 30601941 DOI: 10.1093/brain/awy324] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Accepted: 10/29/2018] [Indexed: 12/25/2022] Open
Abstract
De novo mutations of the sodium channel gene SCN8A result in an epileptic encephalopathy with refractory seizures, developmental delay, and elevated risk of sudden death. p.Arg1872Trp is a recurrent de novo SCN8A mutation reported in 14 unrelated individuals with epileptic encephalopathy that included seizure onset in the prenatal or infantile period and severe verbal and ambulatory comorbidities. The major biophysical effect of the mutation was previously shown to be impaired channel inactivation accompanied by increased current density. We have generated a conditional mouse mutation in which expression of this severe gain-of-function mutation is dependent upon Cre recombinase. Global activation of p.Arg1872Trp by EIIa-Cre resulted in convulsive seizures and lethality at 2 weeks of age. Neural activation of the p.Arg1872Trp mutation by Nestin-Cre also resulted in early onset seizures and death. Restriction of p.Arg1872Trp expression to excitatory neurons using Emx1-Cre recapitulated seizures and juvenile lethality between 1 and 2 months of age. In contrast, activation of p.Arg1872Trp in inhibitory neurons by Gad2-Cre or Dlx5/6-Cre did not induce seizures or overt neurological dysfunction. The sodium channel modulator GS967/Prax330 prolonged survival of mice with global expression of R1872W and also modulated the activity of the mutant channel in transfected cells. Activation of the p.Arg1872Trp mutation in adult mice was sufficient to generate seizures and death, indicating that successful therapy will require lifelong treatment. These findings provide insight into the pathogenic mechanism of this gain-of-function mutation of SCN8A and identify excitatory neurons as critical targets for therapeutic intervention.
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Affiliation(s)
| | - Jacy L Wagnon
- Department of Human Genetics, University of Michigan, Ann Arbor, MI, USA
| | - Eric R Wengert
- Department of Anesthesiology, University of Virginia, Charlottesville VA, USA.,Neuroscience Graduate Program, University of Virginia, Charlottesville VA, USA
| | - Bryan S Barker
- Department of Anesthesiology, University of Virginia, Charlottesville VA, USA.,Neuroscience Graduate Program, University of Virginia, Charlottesville VA, USA
| | - Alexa Faulkner
- Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI, USA
| | - Pravin K Wagley
- Department of Neurology, University of Virginia, Charlottesville VA, USA
| | - Kritika Bhatia
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | - Julie M Jones
- Department of Human Genetics, University of Michigan, Ann Arbor, MI, USA
| | - Marissa R Maniaci
- Department of Human Genetics, University of Michigan, Ann Arbor, MI, USA
| | - Jack M Parent
- Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI, USA.,Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | - Howard P Goodkin
- Neuroscience Graduate Program, University of Virginia, Charlottesville VA, USA.,Department of Neurology, University of Virginia, Charlottesville VA, USA
| | - Manoj K Patel
- Department of Anesthesiology, University of Virginia, Charlottesville VA, USA.,Neuroscience Graduate Program, University of Virginia, Charlottesville VA, USA
| | - Miriam H Meisler
- Department of Human Genetics, University of Michigan, Ann Arbor, MI, USA.,Department of Neurology, University of Michigan, Ann Arbor, MI, USA
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6
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Gardella E, Marini C, Trivisano M, Fitzgerald MP, Alber M, Howell KB, Darra F, Siliquini S, Bölsterli BK, Masnada S, Pichiecchio A, Johannesen KM, Jepsen B, Fontana E, Anibaldi G, Russo S, Cogliati F, Montomoli M, Specchio N, Rubboli G, Veggiotti P, Beniczky S, Wolff M, Helbig I, Vigevano F, Scheffer IE, Guerrini R, Møller RS. The phenotype of SCN8A developmental and epileptic encephalopathy. Neurology 2018; 91:e1112-e1124. [DOI: 10.1212/wnl.0000000000006199] [Citation(s) in RCA: 90] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Accepted: 06/20/2018] [Indexed: 12/20/2022] Open
Abstract
ObjectiveTo delineate the electroclinical features of SCN8A infantile developmental and epileptic encephalopathy (EIEE13, OMIM #614558).MethodsTwenty-two patients, aged 19 months to 22 years, underwent electroclinical assessment.ResultsSixteen of 22 patients had mildly delayed development since birth. Drug-resistant epilepsy started at a median age of 4 months, followed by developmental slowing, pyramidal/extrapyramidal signs (22/22), movement disorders (12/22), cortical blindness (17/22), sialorrhea, and severe gastrointestinal symptoms (15/22), worsening during early childhood and plateauing at age 5 to 9 years. Death occurred in 4 children, following extreme neurologic deterioration, at 22 months to 5.5 years. Nonconvulsive status epilepticus recurred in 14 of 22 patients. The most effective antiepileptic drugs were oxcarbazepine, carbamazepine, phenytoin, and benzodiazepines. EEG showed background deterioration, epileptiform abnormalities with a temporo-occipital predominance, and posterior delta/beta activity correlating with visual impairment. Video-EEG documented focal seizures (FS) (22/22), spasm-like episodes (8/22), cortical myoclonus (8/22), and myoclonic absences (1/22). FS typically clustered and were prolonged (<20 minutes) with (1) cyanosis, hypomotor, and vegetative semiology, sometimes unnoticed, followed by (2) tonic-vibratory and (3) (hemi)-clonic manifestations ± evolution to a bilateral tonic-clonic seizure. FS had posterior-temporal/occipital onset, slowly spreading and sometimes migrating between hemispheres. Brain MRI showed progressive parenchymal atrophy and restriction of the optic radiations.Conclusions:SCN8A developmental and epileptic encephalopathy has strikingly consistent electroclinical features, suggesting a global progressive brain dysfunction primarily affecting the temporo-occipital regions. Both uncontrolled epilepsy and developmental compromise contribute to the profound impairment (increasing risk of death) during early childhood, but stabilization occurs in late childhood.
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7
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Oyrer J, Maljevic S, Scheffer IE, Berkovic SF, Petrou S, Reid CA. Ion Channels in Genetic Epilepsy: From Genes and Mechanisms to Disease-Targeted Therapies. Pharmacol Rev 2018; 70:142-173. [PMID: 29263209 DOI: 10.1124/pr.117.014456] [Citation(s) in RCA: 163] [Impact Index Per Article: 27.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Accepted: 10/02/2017] [Indexed: 12/19/2022] Open
Abstract
Epilepsy is a common and serious neurologic disease with a strong genetic component. Genetic studies have identified an increasing collection of disease-causing genes. The impact of these genetic discoveries is wide reaching-from precise diagnosis and classification of syndromes to the discovery and validation of new drug targets and the development of disease-targeted therapeutic strategies. About 25% of genes identified in epilepsy encode ion channels. Much of our understanding of disease mechanisms comes from work focused on this class of protein. In this study, we review the genetic, molecular, and physiologic evidence supporting the pathogenic role of a number of different voltage- and ligand-activated ion channels in genetic epilepsy. We also review proposed disease mechanisms for each ion channel and highlight targeted therapeutic strategies.
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Affiliation(s)
- Julia Oyrer
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Melbourne, Australia (J.O., S.M., I.E.S., S.P., C.A.R.); Department of Medicine, Austin Health, University of Melbourne, Heidelberg West, Melbourne, Australia (I.E.S., S.F.B.); and Department of Paediatrics, University of Melbourne, Royal Children's Hospital, Melbourne, Australia (I.E.S.)
| | - Snezana Maljevic
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Melbourne, Australia (J.O., S.M., I.E.S., S.P., C.A.R.); Department of Medicine, Austin Health, University of Melbourne, Heidelberg West, Melbourne, Australia (I.E.S., S.F.B.); and Department of Paediatrics, University of Melbourne, Royal Children's Hospital, Melbourne, Australia (I.E.S.)
| | - Ingrid E Scheffer
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Melbourne, Australia (J.O., S.M., I.E.S., S.P., C.A.R.); Department of Medicine, Austin Health, University of Melbourne, Heidelberg West, Melbourne, Australia (I.E.S., S.F.B.); and Department of Paediatrics, University of Melbourne, Royal Children's Hospital, Melbourne, Australia (I.E.S.)
| | - Samuel F Berkovic
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Melbourne, Australia (J.O., S.M., I.E.S., S.P., C.A.R.); Department of Medicine, Austin Health, University of Melbourne, Heidelberg West, Melbourne, Australia (I.E.S., S.F.B.); and Department of Paediatrics, University of Melbourne, Royal Children's Hospital, Melbourne, Australia (I.E.S.)
| | - Steven Petrou
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Melbourne, Australia (J.O., S.M., I.E.S., S.P., C.A.R.); Department of Medicine, Austin Health, University of Melbourne, Heidelberg West, Melbourne, Australia (I.E.S., S.F.B.); and Department of Paediatrics, University of Melbourne, Royal Children's Hospital, Melbourne, Australia (I.E.S.)
| | - Christopher A Reid
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Melbourne, Australia (J.O., S.M., I.E.S., S.P., C.A.R.); Department of Medicine, Austin Health, University of Melbourne, Heidelberg West, Melbourne, Australia (I.E.S., S.F.B.); and Department of Paediatrics, University of Melbourne, Royal Children's Hospital, Melbourne, Australia (I.E.S.)
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8
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Wang J, Gao H, Bao X, Zhang Q, Li J, Wei L, Wu X, Chen Y, Yu S. SCN8A mutations in Chinese patients with early onset epileptic encephalopathy and benign infantile seizures. BMC MEDICAL GENETICS 2017; 18:104. [PMID: 28923014 PMCID: PMC5604297 DOI: 10.1186/s12881-017-0460-1] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Accepted: 09/08/2017] [Indexed: 11/23/2022]
Abstract
Background SCN8A mutations have recently been associated with epilepsy and neurodevelopmental disorders. This study aimed to broaden the phenotypic-spectrum of disease related with SCN8A mutations. Methods To identify the pathogenic gene of a Chinese family, in which six members suffered from epilepsy, whole-exome sequencing was performed. In addition, target next-generation sequencing (NGS) was performed on 178 sporadic patients, who had epilepsy of unknown etiology within 6 months after birth. A detailed clinical history was obtained. Results A heterozygous missense mutation of SCN8A was identified in the Chinese family. Six de novo mutations of SCN8A were detected in 6 sporadic patients with epilepsy. In the family, six members developed seizures within a few years after birth. Five of them had milder clinical performance, that they had normal cognition and developmental milestones, and seizure-free was achieved by mono-therapy. The other one affected member presented with refractory epilepsy and developmental regression. She died from sudden unexpected death in epilepsy (SUDEP) at 17-year-old. Clinical features of six sporadic patients with SCN8A mutations were diverse, ranging from severe epileptic encephalopathy to benign epilepsy with normal cognition. Seizures started at the mean age of 3.9 months (from 2 months to 6 months). Seizure-free was achieved in four of them by mono- or multi-antiepileptic drugs. Five of them demonstrated mild or severe psychomotor retardation, whereas the other one was normal in development and intelligence. Conclusions Our findings extend the spectrum of SCN8A mutations and the clinical features of patients with SCN8A mutations. The majority of SCN8A mutations were de novo, inherited mutations from the heterozygous parents can also occur. The phenotypic spectrum of SCN8A mutation varied largely. Most affected patients manifested as refractory epilepsy and severe intellectual disability, only a small number of patients presented with milder clinical patterns. Additionally, our study confirmed that the same mutation can lead to different phenotypes. Electronic supplementary material The online version of this article (10.1186/s12881-017-0460-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Jiaping Wang
- Department of Pediatrics, Peking University First Hospital, Beijing, 100034, China
| | - Hua Gao
- Center for Bioinformatics, State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing, China
| | - Xinhua Bao
- Department of Pediatrics, Peking University First Hospital, Beijing, 100034, China.
| | - Qingping Zhang
- Department of Pediatrics, Peking University First Hospital, Beijing, 100034, China
| | - Jiarui Li
- Center for Bioinformatics, State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing, China
| | - Liping Wei
- Center for Bioinformatics, State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing, China.
| | - Xiru Wu
- Department of Pediatrics, Peking University First Hospital, Beijing, 100034, China
| | - Yan Chen
- Department of Pediatrics, Peking University First Hospital, Beijing, 100034, China
| | - Shujie Yu
- Department of Neurology, Harbin Children's Hospital, Harbin, Heilongjiang Province, 150010, China
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9
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Reif PS, Tsai MH, Helbig I, Rosenow F, Klein KM. Precision medicine in genetic epilepsies: break of dawn? Expert Rev Neurother 2016; 17:381-392. [DOI: 10.1080/14737175.2017.1253476] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Philipp Sebastian Reif
- Epilepsy Center Frankfurt Rhine-Main, Department of Neurology, Center of Neurology and Neurosurgery, University Hospital, Goethe-University Frankfurt, Frankfurt, Germany
| | - Meng-Han Tsai
- Division of Brain Function & Epilepsy, Department of Neurology, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung, Taiwan
| | - Ingo Helbig
- Division of Neurology, The Children’s Hospital of Philadelphia, Philadelphia, PA, USA
- Department of Neuropediatrics, Christian-Albrechts-University of Kiel and University Medical Center Schleswig-Holstein, Kiel, Germany
- Departments of Brain and Cognitive Sciences, Physiology and Cell Biology, Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Felix Rosenow
- Epilepsy Center Frankfurt Rhine-Main, Department of Neurology, Center of Neurology and Neurosurgery, University Hospital, Goethe-University Frankfurt, Frankfurt, Germany
- Epilepsy Center Hessen, Department of Neurology, University Hospitals Giessen & Marburg, and Philipps-University Marburg, Marburg, Germany
| | - Karl Martin Klein
- Epilepsy Center Frankfurt Rhine-Main, Department of Neurology, Center of Neurology and Neurosurgery, University Hospital, Goethe-University Frankfurt, Frankfurt, Germany
- Epilepsy Center Hessen, Department of Neurology, University Hospitals Giessen & Marburg, and Philipps-University Marburg, Marburg, Germany
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10
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Meisler MH, Helman G, Hammer MF, Fureman BE, Gaillard WD, Goldin AL, Hirose S, Ishii A, Kroner BL, Lossin C, Mefford HC, Parent JM, Patel M, Schreiber J, Stewart R, Whittemore V, Wilcox K, Wagnon JL, Pearl PL, Vanderver A, Scheffer IE. SCN8A encephalopathy: Research progress and prospects. Epilepsia 2016; 57:1027-35. [PMID: 27270488 PMCID: PMC5495462 DOI: 10.1111/epi.13422] [Citation(s) in RCA: 97] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/26/2016] [Indexed: 01/15/2023]
Abstract
On April 21, 2015, the first SCN8A Encephalopathy Research Group convened in Washington, DC, to assess current research into clinical and pathogenic features of the disorder and prepare an agenda for future research collaborations. The group comprised clinical and basic scientists and representatives of patient advocacy groups. SCN8A encephalopathy is a rare disorder caused by de novo missense mutations of the sodium channel gene SCN8A, which encodes the neuronal sodium channel Nav 1.6. Since the initial description in 2012, approximately 140 affected individuals have been reported in publications or by SCN8A family groups. As a result, an understanding of the severe impact of SCN8A mutations is beginning to emerge. Defining a genetic epilepsy syndrome goes beyond identification of molecular etiology. Topics discussed at this meeting included (1) comparison between mutations of SCN8A and the SCN1A mutations in Dravet syndrome, (2) biophysical properties of the Nav 1.6 channel, (3) electrophysiologic effects of patient mutations on channel properties, (4) cell and animal models of SCN8A encephalopathy, (5) drug screening strategies, (6) the phenotypic spectrum of SCN8A encephalopathy, and (7) efforts to develop a bioregistry. A panel discussion of gaps in bioregistry, biobanking, and clinical outcomes data was followed by a planning session for improved integration of clinical and basic science research. Although SCN8A encephalopathy was identified only recently, there has been rapid progress in functional analysis and phenotypic classification. The focus is now shifting from identification of the underlying molecular cause to the development of strategies for drug screening and prioritized patient care.
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Affiliation(s)
- Miriam H. Meisler
- Department of Human Genetics, University of Michigan, Ann Arbor, Michigan, U.S.A
| | - Guy Helman
- Department of Neurology, Children’s National Health System, Washington, District of Columbia, U.S.A
- Center for Genetic Medicine Research, Children’s National Health System, Washington, District of Columbia, U.S.A
| | - Michael F. Hammer
- ARL Division of Biotechnology, University of Arizona, Tucson, Arizona, U.S.A
| | - Brandy E. Fureman
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, U.S.A
| | - William D. Gaillard
- Department of Neurology, Children’s National Health System, Washington, District of Columbia, U.S.A
- Center for Neuroscience Research, Children’s National Health System, Washington, District of Columbia, U.S.A
| | - Alan L. Goldin
- Microbiology & Molecular Genetics and Anatomy & Neurobiology, University of California, Irvine, California, U.S.A
| | - Shinichi Hirose
- Department of Pediatrics, Fukuoka University School of Medicine, Fukuoka, Japan
| | - Atsushi Ishii
- Department of Pediatrics, Fukuoka University School of Medicine, Fukuoka, Japan
| | - Barbara L. Kroner
- Biostatistics and Epidemiology, RTI International, Rockville, Maryland, U.S.A
| | - Christoph Lossin
- Department of Neurology, School of Medicine, University of California Davis, Sacramento, California, U.S.A
| | - Heather C. Mefford
- Division of Genetic Medicine, Department of Pediatrics, University of Washington, Seattle, Washington, U.S.A
| | - Jack M. Parent
- Department of Neurology, University of Michigan Medical Center and VA Ann Arbor Healthcare System, Ann Arbor, Michigan, U.S.A
| | - Manoj Patel
- Department of Anesthesiology, University of Virginia Health System, Charlottesville, Virginia, U.S.A
| | - John Schreiber
- Department of Neurology, Children’s National Health System, Washington, District of Columbia, U.S.A
| | - Randall Stewart
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, U.S.A
| | - Vicky Whittemore
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, U.S.A
| | - Karen Wilcox
- Anticonvulsant Drug Development Program, Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, Utah, U.S.A
| | - Jacy L Wagnon
- Department of Human Genetics, University of Michigan, Ann Arbor, Michigan, U.S.A
| | - Phillip L. Pearl
- Department of Neurology, Boston Children’s Hospital, Harvard Medical School, Boston, Massachusetts, U.S.A
| | - Adeline Vanderver
- Department of Neurology, Children’s National Health System, Washington, District of Columbia, U.S.A
- Center for Genetic Medicine Research, Children’s National Health System, Washington, District of Columbia, U.S.A
- Department of Integrated Systems Biology and Pediatrics, George Washington University, Washington, District of Columbia, U.S.A
| | - Ingrid E. Scheffer
- Department of Neurology, Royal Children’s Hospital, Melbourne, Victoria, Australia
- Department of Paediatrics, University of Melbourne, Melbourne, Victoria, Australia
- Department of Medicine, Epilepsy Research Centre, University of Melbourne, Austin Health, Melbourne, Victoria, Australia
- Florey Institute of Neurosciences and Mental Health, Melbourne, Victoria, Australia
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11
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Møller RS, Johannesen KM. Precision Medicine: SCN8A Encephalopathy Treated with Sodium Channel Blockers. Neurotherapeutics 2016; 13:190-1. [PMID: 26553437 PMCID: PMC4720666 DOI: 10.1007/s13311-015-0403-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
Affiliation(s)
- Rikke S Møller
- The Danish Epilepsy Centre Filadelfia, Dianalund, Denmark.
- Institute for Regional Health Research, University of Southern Denmark, Odense, Denmark.
| | - Katrine M Johannesen
- The Danish Epilepsy Centre Filadelfia, Dianalund, Denmark
- Institute for Regional Health Research, University of Southern Denmark, Odense, Denmark
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12
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Wagnon JL, Barker BS, Hounshell JA, Haaxma CA, Shealy A, Moss T, Parikh S, Messer RD, Patel MK, Meisler MH. Pathogenic mechanism of recurrent mutations of SCN8A in epileptic encephalopathy. Ann Clin Transl Neurol 2015; 3:114-23. [PMID: 26900580 PMCID: PMC4748308 DOI: 10.1002/acn3.276] [Citation(s) in RCA: 82] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Accepted: 11/20/2015] [Indexed: 12/03/2022] Open
Abstract
Objective The early infantile epileptic encephalopathy type 13 (EIEE13, OMIM #614558) results from de novo missense mutations of SCN8A encoding the voltage‐gated sodium channel Nav1.6. More than 20% of patients have recurrent mutations in residues Arg1617 or Arg1872. Our goal was to determine the functional effects of these mutations on channel properties. Methods Clinical exome sequencing was carried out on patients with early‐onset seizures, developmental delay, and cognitive impairment. Two mutations identified here, p.Arg1872Leu and p.Arg1872Gln, and two previously identified mutations, p.Arg1872Trp and p.Arg1617Gln, were introduced into Nav1.6 cDNA, and effects on electrophysiological properties were characterized in transfected ND7/23 cells. Interactions with FGF14, G‐protein subunit Gβγ, and sodium channel subunit β1 were assessed by coimmunoprecipitation. Results We identified two patients with the novel mutation p.Arg1872Leu and one patient with the recurrent mutation p.Arg1872Gln. The three mutations of Arg1872 and the mutation of Arg1617 all impaired the sodium channel transition from open state to inactivated state, resulting in channel hyperactivity. Other observed abnormalities contributing to elevated channel activity were increased persistent current, increased peak current density, hyperpolarizing shift in voltage dependence of activation, and depolarizing shift in steady‐state inactivation. Protein interactions were not affected. Interpretation Recurrent mutations at Arg1617 and Arg1872 lead to elevated Nav1.6 channel activity by impairing channel inactivation. Channel hyperactivity is the major pathogenic mechanism for gain‐of‐function mutations of SCN8A. EIEE13 differs mechanistically from Dravet syndrome, which is caused by loss‐of‐function mutations of SCN1A. This distinction has important consequences for selection of antiepileptic drugs and the development of gene‐ and mutation‐specific treatments.
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Affiliation(s)
- Jacy L Wagnon
- Department of Human Genetics University of Michigan Ann Arbor Michigan
| | - Bryan S Barker
- Department of Anesthesiology and Neuroscience Graduate Program University of Virginia Health System Charlottesville Virginia
| | - James A Hounshell
- Department of Anesthesiology and Neuroscience Graduate Program University of Virginia Health System Charlottesville Virginia
| | - Charlotte A Haaxma
- Department of Pediatric Neurology Radboud University Nijmegen The Netherlands
| | - Amy Shealy
- Cleveland Clinic Genomic Medicine Institute Cleveland Ohio
| | - Timothy Moss
- Cleveland Clinic Genomic Medicine Institute Cleveland Ohio
| | - Sumit Parikh
- Department of Pediatric Neurology Cleveland Clinic Cleveland Ohio
| | - Ricka D Messer
- Department of Pediatric Neurology Johns Hopkins Medical Institute Baltimore Maryland
| | - Manoj K Patel
- Department of Anesthesiology and Neuroscience Graduate Program University of Virginia Health System Charlottesville Virginia
| | - Miriam H Meisler
- Department of Human Genetics University of Michigan Ann Arbor Michigan
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