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Zhang Q, Forster-Gibson C, Bercovici E, Bernardo A, Ding F, Shen W, Langer K, Rex T, Kang JQ. Epilepsy plus blindness in microdeletion of GABRA1 and GABRG2 in mouse and human. Exp Neurol 2023; 369:114537. [PMID: 37703949 PMCID: PMC10591898 DOI: 10.1016/j.expneurol.2023.114537] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2023] [Revised: 08/24/2023] [Accepted: 09/07/2023] [Indexed: 09/15/2023]
Abstract
OBJECTIVE GABAA receptor subunit gene (GABR) mutations are significant causes of epilepsy, including syndromic epilepsy. This report for the first time, describes intractable epilepsy and blindness due to optic atrophy in our patient, who has a microdeletion of the GABRA1 and GABRG2 genes. We then characterized the molecular phenotypes and determined patho-mechanisms underlying the genotype-phenotype correlations in a mouse model who is haploinsufficient for both genes (Gabra1+/-/Gabrg2+/- mouse). METHODS Electroencephalography was conducted in both human and mice with the same gene loss. GABAA receptor expression was evaluated by biochemical and imaging approaches. Optic nerve atrophy was evaluated with fundus photography in human while electronic microscopy, visual evoked potential and electroretinography recordings were conducted in mice. RESULTS The patient has bilateral optical nerve atrophy. Mice displayed spontaneous seizures, reduced electroretinography oscillatory potential and reduced GABAA receptor α1, β2 and γ2 subunit expression in various brain regions. Electronic microscopy showed that mice also had optic nerve degeneration, as indicated by increased G-ratio, the ratio of the inner axonal diameter to the total outer diameter, suggesting impaired myelination of axons. More importantly, we identified that phenobarbital was the most effective anticonvulsant in mice and the patient's seizures were also controlled with phenobarbital after failing multiple anti-seizure drugs. CONCLUSIONS This study is the first report of haploinsufficiency of two GABR epilepsy genes and visual impairment due to altered axonal myelination and resultant optic nerve atrophy. The study suggests the far-reaching impact of GABR mutations and the translational significance of animal models with the same etiology.
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Affiliation(s)
- Qi Zhang
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN 37212, United States of America; Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-innovation Center of Neuroregeneration, Department of Neurology, Nantong University, 19 Qixiu Road, Nantong, JS 226001, PR China
| | - Cynthia Forster-Gibson
- Laboratory Medicine and Genetics, Trillium Health Partners, Mississauga and Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Canada
| | - Eduard Bercovici
- Division of Neurology, Faculty of Medicine, University of Toronto, Canada
| | - Alexandra Bernardo
- Department of Ophthalmology & Visual Sciences Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, TN 37212, United States of America
| | - Fei Ding
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-innovation Center of Neuroregeneration, Department of Neurology, Nantong University, 19 Qixiu Road, Nantong, JS 226001, PR China
| | - Wangzhen Shen
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN 37212, United States of America
| | - Katherine Langer
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN 37212, United States of America
| | - Tonia Rex
- Department of Ophthalmology & Visual Sciences Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, TN 37212, United States of America
| | - Jing-Qiong Kang
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN 37212, United States of America; Department of Pharmacology, Vanderbilt University, United States of America; Vanderbilt Brain Institute and Vanderbilt Kennedy Center of Human Development, Vanderbilt University, Nashville, TN 37212, United States of America.
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2
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Kuanyshbek A, Wang M, Andersson Å, Tuifua M, Palmer EE, Sachdev RK, Mu TW, Vetter I, Keramidas A. Anti-seizure mechanisms of midazolam and valproate at the β2(L51M) variant of the GABA A receptor. Neuropharmacology 2022; 221:109295. [PMID: 36257447 PMCID: PMC9981329 DOI: 10.1016/j.neuropharm.2022.109295] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2022] [Revised: 10/07/2022] [Accepted: 10/11/2022] [Indexed: 11/05/2022]
Abstract
Genetic sequencing is identifying an expanding number of variants of GABAA receptors associated with human epilepsies. We identified a new de novo variant of the β2 subunit (β2L51M) of the inhibitory GABAA receptor associated with seizures. Our analysis determined the pathogenicity of the variant and the effects of anti-seizure medications. Our data demonstrates that the variant reduced cell surface trafficking and peak GABA-gated currents. Synaptic currents mediated by variant-containing receptors decayed faster than wild-type and single receptor currents showed that the variant shortened the duration of receptor activity by decreasing receptor open times. We tested the effects of the anti-seizure medications, midazolam, carbamazepine and valproate and found that all three enhance variant receptor surface expression. Additionally, midazolam restored receptor function by increasing single receptor active periods and synaptic current decay times towards wild-type levels. By contrast, valproate increased synaptic peak currents, event frequency and promoted synaptic bursting. Our study identifies a new disease-causing variant to the GABAA receptor, profiles its pathogenic effects and demonstrates how anti-seizure drugs correct its functional deficits.
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Affiliation(s)
- Alibek Kuanyshbek
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Australia
| | - Meng Wang
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, OH, 44106, USA
| | - Åsa Andersson
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Australia
| | - Marie Tuifua
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Australia
| | - Elizabeth E Palmer
- Sydney Children's Hospital Network, Randwick Sydney Australia and School of Women's and Children's Health, UNSW Medicine, The University of New South Wales, Sydney, NSW, Australia
| | - Rani K Sachdev
- Sydney Children's Hospital Network, Randwick Sydney Australia and School of Women's and Children's Health, UNSW Medicine, The University of New South Wales, Sydney, NSW, Australia
| | - Ting-Wei Mu
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, OH, 44106, USA
| | - Irina Vetter
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Australia; School of Pharmacy, The University of Queensland, Woolloongabba, Queensland, 4102, Australia
| | - Angelo Keramidas
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Australia.
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3
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Feng Y, Wei ZH, Liu C, Li GY, Qiao XZ, Gan YJ, Zhang CC, Deng YC. Genetic variations in GABA metabolism and epilepsy. Seizure 2022; 101:22-29. [PMID: 35850019 DOI: 10.1016/j.seizure.2022.07.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 07/10/2022] [Accepted: 07/11/2022] [Indexed: 11/18/2022] Open
Abstract
Epilepsy is a paroxysmal brain disorder that results from an imbalance between neuronal excitation and inhibition. Gamma-aminobutyric acid (GABA) is the most important inhibitory neurotransmitter in the brain and plays an important role in the occurrence and development of epilepsy. Abnormalities in all aspects of GABA metabolism, including GABA synthesis, transport, genes encoding GABA receptors, and GABA inactivation, may lead to epilepsy. GABRA1, GABRA2, GABRA5, GABRB1, GABRB2, GABRB3, GABRG2 and GABBR2 are genes that encode GABA receptors and are commonly associated with epilepsy. Mutations of these genes lead to a variety of epilepsy syndromes with different clinical phenotypes, primarily by down regulating receptor expression and reducing the amplitude of GABA-evoked potentials. GABA is metabolized by GABA transaminase and succinate semi aldehyde dehydrogenase, which are encoded by the ABAT and ALDH5A1 genes, respectively. Mutations of these genes result in symptoms related to deficiency of GABA transaminase and succinate semi aldehyde dehydrogenase, such as epilepsy and cognitive impairment. Most of the variation in genes associated with GABA metabolism are accompanied by developmental disorders. This review focuses on advances in understanding the relationship between genetic variation in GABA metabolism and epilepsy to establish a basis for the accurate diagnosis and treatment of epilepsy.
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Affiliation(s)
- Yan Feng
- Xi'an Medical University, Xi'an 710021, People's Republic of China; Department of Neurology, Epilepsy Center of Xijing Hospital, Fourth Military Medical University, Xi'an 710032, People's Republic of China
| | - Zi-Han Wei
- Department of Neurology, Epilepsy Center of Xijing Hospital, Fourth Military Medical University, Xi'an 710032, People's Republic of China
| | - Chao Liu
- Department of Neurology, Epilepsy Center of Xijing Hospital, Fourth Military Medical University, Xi'an 710032, People's Republic of China
| | - Guo-Yan Li
- Xi'an Medical University, Xi'an 710021, People's Republic of China; Department of Neurology, Epilepsy Center of Xijing Hospital, Fourth Military Medical University, Xi'an 710032, People's Republic of China
| | - Xiao-Zhi Qiao
- Department of Neurology, Epilepsy Center of Xijing Hospital, Fourth Military Medical University, Xi'an 710032, People's Republic of China
| | - Ya-Jing Gan
- Department of Neurology, Epilepsy Center of Xijing Hospital, Fourth Military Medical University, Xi'an 710032, People's Republic of China
| | - Chu-Chu Zhang
- Xi'an Medical University, Xi'an 710021, People's Republic of China
| | - Yan-Chun Deng
- Department of Neurology, Epilepsy Center of Xijing Hospital, Fourth Military Medical University, Xi'an 710032, People's Republic of China.
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4
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Absalom NL, Liao VWY, Johannesen KMH, Gardella E, Jacobs J, Lesca G, Gokce-Samar Z, Arzimanoglou A, Zeidler S, Striano P, Meyer P, Benkel-Herrenbrueck I, Mero IL, Rummel J, Chebib M, Møller RS, Ahring PK. Gain-of-function and loss-of-function GABRB3 variants lead to distinct clinical phenotypes in patients with developmental and epileptic encephalopathies. Nat Commun 2022; 13:1822. [PMID: 35383156 PMCID: PMC8983652 DOI: 10.1038/s41467-022-29280-x] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Accepted: 03/08/2022] [Indexed: 12/23/2022] Open
Abstract
Many patients with developmental and epileptic encephalopathies present with variants in genes coding for GABAA receptors. These variants are presumed to cause loss-of-function receptors leading to reduced neuronal GABAergic activity. Yet, patients with GABAA receptor variants have diverse clinical phenotypes and many are refractory to treatment despite the availability of drugs that enhance GABAergic activity. Here we show that 44 pathogenic GABRB3 missense variants segregate into gain-of-function and loss-of-function groups and respective patients display distinct clinical phenotypes. The gain-of-function cohort (n = 27 patients) presented with a younger age of seizure onset, higher risk of severe intellectual disability, focal seizures at onset, hypotonia, and lower likelihood of seizure freedom in response to treatment. Febrile seizures at onset are exclusive to the loss-of-function cohort (n = 47 patients). Overall, patients with GABRB3 variants that increase GABAergic activity have more severe developmental and epileptic encephalopathies. This paradoxical finding challenges our current understanding of the GABAergic system in epilepsy and how patients should be treated.
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Affiliation(s)
- Nathan L Absalom
- Brain and Mind Centre, School of Pharmacy, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia.,School of Science, Western Sydney University, Sydney, NSW, Australia
| | - Vivian W Y Liao
- Brain and Mind Centre, School of Pharmacy, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
| | - Katrine M H Johannesen
- Department of Epilepsy Genetics and Personalized Treatment, Member of the ERN EpiCARE, The Danish Epilepsy Centre, Dianalund, Denmark.,Department of Regional Health Research, University of Southern Denmark, Odense, Denmark
| | - Elena Gardella
- Department of Epilepsy Genetics and Personalized Treatment, Member of the ERN EpiCARE, The Danish Epilepsy Centre, Dianalund, Denmark.,Department of Regional Health Research, University of Southern Denmark, Odense, Denmark
| | - Julia Jacobs
- Department of Neuropediatrics and Muscle Disorders, Medical Center-University of Freiburg, Freiburg, Germany.,Department of Paediatrics and Department of Neuroscience, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada.,Hotchkiss Brain Institute and Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB, Canada
| | - Gaetan Lesca
- Department of Medical Genetics, Member of the ERN EpiCARE, University Hospitals of Lyon (HCL), Lyon, France.,Institut Neuromyogène, CNRS UMR 5310 - INSERM U1217, Université de Lyon, Université Claude Bernard Lyon 1, Lyon, France
| | - Zeynep Gokce-Samar
- Department of Paediatric Clinical Epileptology, Sleep Disorders and Functional Neurology, Member of the ERN EpiCARE, University Hospitals of Lyon (HCL), Lyon, France
| | - Alexis Arzimanoglou
- Department of Paediatric Clinical Epileptology, Sleep Disorders and Functional Neurology, Member of the ERN EpiCARE, University Hospitals of Lyon (HCL), Lyon, France
| | - Shimriet Zeidler
- Department of Clinical Genetics, Erasmus MC, Rotterdam, The Netherlands
| | - Pasquale Striano
- IRCCS Institute "Giannina Gaslini", Genova, Italy.,Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genova, Genova, Italy
| | - Pierre Meyer
- Pediatric Neurology Department, Phymedexp, Montpellier University, Inserm, CRNS, Montpellier University Hospital, Montpellier, France
| | - Ira Benkel-Herrenbrueck
- Sana-Krankenhaus Düsseldorf-Gerresheim, Academic Teaching Hospital der Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
| | - Inger-Lise Mero
- Department of Medical Genetics, Oslo University Hospital, Oslo, Norway
| | - Jutta Rummel
- Department of Neurohabilitation, Oslo University Hospital, Oslo, Norway
| | - Mary Chebib
- Brain and Mind Centre, School of Pharmacy, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
| | - Rikke S Møller
- Department of Epilepsy Genetics and Personalized Treatment, Member of the ERN EpiCARE, The Danish Epilepsy Centre, Dianalund, Denmark. .,Department of Regional Health Research, University of Southern Denmark, Odense, Denmark.
| | - Philip K Ahring
- Brain and Mind Centre, School of Pharmacy, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia.
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5
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Barki M, Xue H. GABRB2, a key player in neuropsychiatric disorders and beyond. Gene 2022; 809:146021. [PMID: 34673206 DOI: 10.1016/j.gene.2021.146021] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2020] [Revised: 08/05/2021] [Accepted: 09/14/2021] [Indexed: 01/11/2023]
Abstract
The GABA receptors represent the main inhibitory system in the central nervous system that ensure synaptogenesis, neurogenesis, and the regulation of neuronal plasticity and learning. GABAA receptors are pentameric in structure and belong to the Cys-loop superfamily. The GABRB2 gene, located on chromosome 5q34, encodes the β2 subunit that combines with the α and γ subunits to form the major subtype of GABAA receptors, which account for 43% of all GABAA receptors in the mammalian brain. Each subunit probably consists of an extracellular N-terminal domain, four membrane-spanning segments, a large intracellular loop between TM3 and TM4, and an extracellular C-terminal domain. Alternative splicing of the RNA transcript of the GABRB2 gene gives rise at least to four long and short isoforms with dissimilar electrophysiological properties. Furthermore, GABRB2 is imprinted and subjected to epigenetic regulation and positive selection. It has been associated with schizophrenia first in Han Chinese, and subsequently validated in other populations. Gabrb2 knockout mice also exhibited schizophrenia-like behavior and neuroinflammation that were ameliorated by the antipsychotic drug risperidone. GABRB2 was also associated with other neuropsychiatric disorders including bipolar disorder, epilepsy, autism spectrum disorder, Alzheimer's disease, frontotemporal dementia, substance dependence, depression, internet gaming disorder, and premenstrual dysphoric disorder. Recently, it has been postulated that GABRB2 might be a potential marker for different cancer types. As GABRB2 has a pivotal role in the central nervous system and is increasingly recognized to contribute to human diseases, further understanding of its structure and function may expedite the generation of new therapeutic approaches.
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Affiliation(s)
- Manel Barki
- Center for Cancer Genomics, School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, Jiangsu, China
| | - Hong Xue
- Center for Cancer Genomics, School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, Jiangsu, China; Division of Life Science and Applied Genomics Center, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China.
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6
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Swanson LC, Ahmed R. Epilepsy Syndromes: Current Classifications and Future Directions. Neurosurg Clin N Am 2021; 33:113-134. [PMID: 34801136 DOI: 10.1016/j.nec.2021.09.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
This review describes the clinical presentations and treatment options for commonly recognized epilepsy syndromes in the pediatric age group, based on the 2017 International League Against Epilepsy classification. Structural epilepsies that are amenable to surgical intervention are discussed. Lastly, emerging technologies are reviewed that are expanding our knowledge of underlying epilepsy pathologies and will guide future syndromic classification systems including genetic testing and tissue repositories.
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Affiliation(s)
- Laura C Swanson
- Department of Pediatrics, Ann & Robert H. Lurie Children's Hospital of Chicago, 225 E. Chicago Ave. #18, Chicago, IL 60611, USA
| | - Raheel Ahmed
- Department of Neurosurgery, University of Wisconsin-Madison School of Medicine and Public Health, 1675 Highland Avenue #0002, Madison, WI 53705, USA.
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7
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Hernandez CC, Tian X, Hu N, Shen W, Catron MA, Yang Y, Chen J, Jiang Y, Zhang Y, Macdonald RL. Dravet syndrome-associated mutations in GABRA1, GABRB2 and GABRG2 define the genetic landscape of defects of GABA A receptors. Brain Commun 2021; 3:fcab033. [PMID: 34095830 PMCID: PMC8176149 DOI: 10.1093/braincomms/fcab033] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Revised: 01/07/2021] [Accepted: 01/14/2021] [Indexed: 12/29/2022] Open
Abstract
Dravet syndrome is a rare, catastrophic epileptic encephalopathy that begins in the first year of life, usually with febrile or afebrile hemiclonic or generalized tonic-clonic seizures followed by status epilepticus. De novo variants in genes that mediate synaptic transmission such as SCN1A and PCDH19 are often associated with Dravet syndrome. Recently, GABAA receptor subunit genes (GABRs) encoding α1 (GABRA1), β3 (GABRB3) and γ2 (GABRG2), but not β2 (GABRB2) or β1 (GABRB1), subunits are frequently associated with Dravet syndrome or Dravet syndrome-like phenotype. We performed next generation sequencing on 870 patients with Dravet syndrome and identified nine variants in three different GABRs. Interestingly, the variants were all in genes encoding the most common GABAA receptor, the α1β2γ2 receptor. Mutations in GABRA1 (c.644T>C, p. L215P; c.640C>T, p. R214C; c.859G>A; V287I; c.641G>A, p. R214H) and GABRG2 (c.269C>G, p. T90R; c.1025C>T, p. P342L) presented as de novo cases, while in GABRB2 two variants were de novo (c.992T>C, p. F331S; c.542A>T, p. Y181F) and one was autosomal dominant and inherited from the maternal side (c.990_992del, p.330_331del). We characterized the effects of these GABR variants on GABAA receptor biogenesis and channel function. We found that defects in receptor gating were the common deficiency of GABRA1 and GABRB2 Dravet syndrome variants, while mainly trafficking defects were found with the GABRG2 (c.269C>G, p. T90R) variant. It seems that variants in α1 and β2 subunits are less tolerated than in γ2 subunits, since variant α1 and β2 subunits express well but were functionally deficient. This suggests that all of these GABR variants are all targeting GABR genes that encode the assembled α1β2γ2 receptor, and regardless of which of the three subunits are mutated, variants in genes coding for α1, β2 and γ2 receptor subunits make them candidate causative genes in the pathogenesis of Dravet syndrome.
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Affiliation(s)
- Ciria C Hernandez
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48198, USA
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN 37240, USA
| | - XiaoJuan Tian
- Department of Pediatrics and Pediatric Epilepsy Center, Peking University First Hospital, Beijing 100034, China
- Department of Neurology, Beijing Children’s Hospital, Capital Medical University, National Center for Children’s Health, Beijing 100045, China
| | - Ningning Hu
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN 37240, USA
| | - Wangzhen Shen
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN 37240, USA
| | - Mackenzie A Catron
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN 37240, USA
- Neuroscience Graduate Program, Vanderbilt University, Nashville, TN 37240, USA
| | - Ying Yang
- Department of Pediatrics and Pediatric Epilepsy Center, Peking University First Hospital, Beijing 100034, China
| | - Jiaoyang Chen
- Department of Pediatrics and Pediatric Epilepsy Center, Peking University First Hospital, Beijing 100034, China
| | - Yuwu Jiang
- Department of Pediatrics and Pediatric Epilepsy Center, Peking University First Hospital, Beijing 100034, China
- Center of Epilepsy, Beijing Institute for Brain Disorders, Beijing 100069, China
| | - Yuehua Zhang
- Department of Pediatrics and Pediatric Epilepsy Center, Peking University First Hospital, Beijing 100034, China
| | - Robert L Macdonald
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN 37240, USA
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8
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Garcia-Rosa S, de Freitas Brenha B, Felipe da Rocha V, Goulart E, Araujo BHS. Personalized Medicine Using Cutting Edge Technologies for Genetic Epilepsies. Curr Neuropharmacol 2021; 19:813-831. [PMID: 32933463 PMCID: PMC8686309 DOI: 10.2174/1570159x18666200915151909] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 08/08/2020] [Accepted: 08/28/2020] [Indexed: 11/22/2022] Open
Abstract
Epilepsy is the most common chronic neurologic disorder in the world, affecting 1-2% of the population. Besides, 30% of epilepsy patients are drug-resistant. Genomic mutations seem to play a key role in its etiology and knowledge of strong effect mutations in protein structures might improve prediction and the development of efficacious drugs to treat epilepsy. Several genetic association studies have been undertaken to examine the effect of a range of candidate genes for resistance. Although, few studies have explored the effect of the mutations into protein structure and biophysics in the epilepsy field. Much work remains to be done, but the plans made for exciting developments will hold therapeutic potential for patients with drug-resistance. In summary, we provide a critical review of the perspectives for the development of individualized medicine for epilepsy based on genetic polymorphisms/mutations in light of core elements such as transcriptomics, structural biology, disease model, pharmacogenomics and pharmacokinetics in a manner to improve the success of trial designs of antiepileptic drugs.
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Affiliation(s)
- Sheila Garcia-Rosa
- Brazilian Biosciences National Laboratory (LNBio), Center for Research in Energy and Material (CNPEM), Campinas, SP, Brazil
| | - Bianca de Freitas Brenha
- Laboratory of Embryonic Genetic Regulation, Department of Biochemistry and Tissue Biology, Institute of Biology, University of Campinas, Campinas, SP, Brazil
| | - Vinicius Felipe da Rocha
- Brazilian Biosciences National Laboratory (LNBio), Center for Research in Energy and Material (CNPEM), Campinas, SP, Brazil
| | - Ernesto Goulart
- Human Genome and Stem-Cell Research Center (HUG-CEL), Department of Genetics and Evolutionary Biology, Institute of Biosciences, University of São Paulo, SP, Brazil
| | - Bruno Henrique Silva Araujo
- Brazilian Biosciences National Laboratory (LNBio), Center for Research in Energy and Material (CNPEM), Campinas, SP, Brazil
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9
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El Achkar CM, Harrer M, Smith L, Kelly M, Iqbal S, Maljevic S, Niturad CE, Vissers LELM, Poduri A, Yang E, Lal D, Lerche H, Møller RS, Olson HE. Characterization of the GABRB2-Associated Neurodevelopmental Disorders. Ann Neurol 2020; 89:573-586. [PMID: 33325057 DOI: 10.1002/ana.25985] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2020] [Revised: 11/30/2020] [Accepted: 12/01/2020] [Indexed: 11/09/2022]
Abstract
OBJECTIVE We aimed to characterize the phenotypic spectrum and functional consequences associated with variants in the gene GABRB2, coding for the γ-aminobutyric acid type A (GABAA ) receptor subunit β2. METHODS We recruited and systematically evaluated 25 individuals with variants in GABRB2, 17 of whom are newly described and 8 previously reported with additional clinical data. Functional analysis was performed using a Xenopus laevis oocyte model system. RESULTS Our cohort of 25 individuals from 22 families with variants in GABRB2 demonstrated a range of epilepsy phenotypes from genetic generalized epilepsy to developmental and epileptic encephalopathy. Fifty-eight percent of individuals had pharmacoresistant epilepsy; response to medications targeting the GABAergic pathway was inconsistent. Developmental disability (present in 84%) ranged from mild intellectual disability to severe global disability; movement disorders (present in 44%) included choreoathetosis, dystonia, and ataxia. Disease-associated variants cluster in the extracellular N-terminus and transmembrane domains 1-3, with more severe phenotypes seen in association with variants in transmembrane domains 1 and 2 and the allosteric binding site between transmembrane domains 2 and 3. Functional analysis of 4 variants in transmembrane domains 1 or 2 (p.Ile246Thr, p.Pro252Leu, p.Ile288Ser, p.Val282Ala) revealed strongly reduced amplitudes of GABA-evoked anionic currents. INTERPRETATION GABRB2-related epilepsy ranges broadly in severity from genetic generalized epilepsy to developmental and epileptic encephalopathies. Developmental disability and movement disorder are key features. The phenotypic spectrum is comparable to other GABAA receptor-encoding genes. Phenotypic severity varies by protein domain. Experimental evidence supports loss of GABAergic inhibition as the mechanism underlying GABRB2-associated neurodevelopmental disorders. ANN NEUROL 2021;89:573-586.
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Affiliation(s)
- Christelle M El Achkar
- Division of Epilepsy and Clinical Neurophysiology and Epilepsy Genetics Program, Department of Neurology, Boston Children's Hospital, Boston, MA.,Department of Neurology, Harvard Medical School, Boston, MA
| | - Merle Harrer
- Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Lacey Smith
- Division of Epilepsy and Clinical Neurophysiology and Epilepsy Genetics Program, Department of Neurology, Boston Children's Hospital, Boston, MA
| | - McKenna Kelly
- Division of Epilepsy and Clinical Neurophysiology and Epilepsy Genetics Program, Department of Neurology, Boston Children's Hospital, Boston, MA.,Dartmouth Geisel School of Medicine, Hanover, NH
| | - Sumaiya Iqbal
- Center for Development of Therapeutics and Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA
| | - Snezana Maljevic
- Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany.,Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Australia
| | - Cristina E Niturad
- Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Lisenka E L M Vissers
- Department of Human Genetics, Donders Institute for Brain, Cognition, and Behavior, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Annapurna Poduri
- Division of Epilepsy and Clinical Neurophysiology and Epilepsy Genetics Program, Department of Neurology, Boston Children's Hospital, Boston, MA.,Department of Neurology, Harvard Medical School, Boston, MA
| | - Edward Yang
- Department of Radiology, Boston Children's Hospital, Boston, MA
| | - Dennis Lal
- Cleveland Clinic Genomic Medicine Institute and Neurological Institute, Cleveland, OH
| | - Holger Lerche
- Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Rikke S Møller
- Department of Epilepsy Genetics and Personalized Treatment, Danish Epilepsy Center Filadelfia, Dianalund, Denmark.,Department of Regional Health Research, University of Southern Denmark, Odense, Denmark
| | - Heather E Olson
- Division of Epilepsy and Clinical Neurophysiology and Epilepsy Genetics Program, Department of Neurology, Boston Children's Hospital, Boston, MA.,Department of Neurology, Harvard Medical School, Boston, MA
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10
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Xu Y, Wu BB, Wang HJ, Zhou SZ, Cheng GQ, Zhou YF. A term neonate with early myoclonic encephalopathy caused by RARS2 gene variants: a case report. Transl Pediatr 2020; 9:707-712. [PMID: 33209735 PMCID: PMC7658767 DOI: 10.21037/tp-20-110] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The RARS2 gene encodes mitochondrial arginine-tRNA synthetase. Patients with variants of the RARS2 gene have pontocerebellar hypoplasia type 6 (PCH6), which is characterized by early onset seizures, progressive microcephaly, and developmental delay. PCH6 is a rare mitochondrial encephalopathy. To the best of our knowledge, the onset seizure type which the ictal video-electroencephalogram (VEEG) was compatible with early myoclonic encephalopathy (EME) has not been reported. Here we reported a term female neonate with EME caused by heterozygous variants of the RARS2 gene [NM_020320: exon10: c.773G>A (p. R258H) Maternal, NM_020320: exon4: c.282_285delAGAG Paternal]. Groan was the first symptom manifested, followed by metabolic disorders, and early marked cerebral atrophy. Metabolic disorders were corrected after feeding with extensively hydrolyzed protein formula. Seizures started at the 19th day of life. Interictal VEEG showed a suppression-burst (SB) pattern and ictal VEEG revealed myoclonic seizures that were compatible with early myoclonic encephalopathy (EME). She had frequent myoclonic seizures resistant to multi-antiepileptic drugs including phenobarbital, levetiracetam and oxcarbazepine, and soon developed into convulsive status epilepticus. At 7 months of age, she had severe developmental delay, and developed infantile spasms. Our case report expands the phenotypic spectrum of the PCH6, meanwhile, RARS2 should be considered be a causative gene in patients with EME.
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Affiliation(s)
- Yan Xu
- Department of Neurology, Children's Hospital of Fudan University, Shanghai, China
| | - Bing-Bing Wu
- The Molecular Genetic Diagnosis Center, Shanghai Key Lab of Birth Defects, Pediatrics Research Institute, Children's Hospital of Fudan University, Shanghai, China
| | - Hui-Jun Wang
- The Molecular Genetic Diagnosis Center, Shanghai Key Lab of Birth Defects, Pediatrics Research Institute, Children's Hospital of Fudan University, Shanghai, China
| | - Shui-Zhen Zhou
- Department of Neurology, Children's Hospital of Fudan University, Shanghai, China
| | - Guo-Qiang Cheng
- Department of Neonatology, Children's Hospital of Fudan University, Shanghai, China
| | - Yuan-Feng Zhou
- Department of Neurology, Children's Hospital of Fudan University, Shanghai, China
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11
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Yang Y, Xiangwei W, Zhang X, Xiao J, Chen J, Yang X, Jia T, Yang Z, Jiang Y, Zhang Y. Phenotypic spectrum of patients with GABRB2 variants: from mild febrile seizures to severe epileptic encephalopathy. Dev Med Child Neurol 2020; 62:1213-1220. [PMID: 32686847 DOI: 10.1111/dmcn.14614] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 05/26/2020] [Indexed: 12/19/2022]
Abstract
AIM To characterize the different phenotypes of GABRB2-related epilepsy and to establish a genotype-phenotype correlation. METHOD We used next-generation sequencing to identify GABRB2 variants in 15 patients. RESULTS Eleven GABRB2 variants were novel and 12 were de novo. The age at the onset of seizures ranged from 1 day to 26 months. Nine patients had multiple seizure types, including focal seizures, generalized tonic-clonic seizures, myoclonic seizures, epileptic spasms, and atonic seizures. Seizures were fever-sensitive in 13 out of the 15 patients. Eleven patients displayed developmental delay, while 11 had abnormal video electroencephalography. Abnormalities in the brain images included dysplasia of the frontal and temporal cortex, dysplasia of the corpus callosum, and delayed myelination in four patients. One patient was diagnosed with febrile seizures, three with febrile seizures plus, three with Dravet syndrome, three with West syndrome, one with Ohtahara syndrome, three with developmental delays and epilepsy, and one with non-specific early-onset epileptic encephalopathy. INTERPRETATION The most common phenotypes of patients with GABRB2 variants include early onset of seizure and fever sensitivity. Febrile seizures and febrile seizures plus are new phenotypes of GABRB2 variants. The phenotypic spectrum of GABRB2 variants ranges from mild febrile seizures to severe epileptic encephalopathy.
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Affiliation(s)
- Ying Yang
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Wenshu Xiangwei
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Xiaoli Zhang
- Department of Pediatrics, The Third Affiliated Hospital of Zheng Zhou University, Zhengzhou, China
| | - Jiangxi Xiao
- Department of Radiology, Peking University First Hospital, Beijing, China
| | - Jiaoyang Chen
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Xiaoling Yang
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Tianming Jia
- Department of Pediatrics, The Third Affiliated Hospital of Zheng Zhou University, Zhengzhou, China
| | - Zhixian Yang
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Yuwu Jiang
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Yuehua Zhang
- Department of Pediatrics, Peking University First Hospital, Beijing, China
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12
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Markus F, Angelini C, Trimouille A, Rudolf G, Lesca G, Goizet C, Lasseaux E, Arveiler B, van Slegtenhorst M, Brooks AS, Abou Jamra R, Korenke GC, Neidhardt J, Owczarek-Lipska M. Rare variants in the GABA A receptor subunit ε identified in patients with a wide spectrum of epileptic phenotypes. Mol Genet Genomic Med 2020; 8:e1388. [PMID: 32588540 PMCID: PMC7507344 DOI: 10.1002/mgg3.1388] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Revised: 05/29/2020] [Accepted: 05/31/2020] [Indexed: 01/08/2023] Open
Abstract
Background Epilepsy belongs to a group of chronic and highly heterogeneous brain disorders. Many types of epilepsy and epileptic syndromes are caused by genetic factors. The neural amino acid y‐aminobutyric acid (GABA) is a major inhibitory neurotransmitter in the mammalian central nervous system. It regulates activity of channel pores by binding to transmembrane GABA‐receptors (GABRs). The GABRs are heteropentamers assembled from different receptor subunits (α1‐6, β1‐3, γ1‐3, δ, ε, θ, π, and ρ1‐3). Several epileptic disorders are caused by mutations in genes encoding single GABRs. Methods We applied trio‐ and single‐whole exome sequencing to search for genetic sequence variants associated with a wide range of epileptic phenotypes accompanied by intellectual disability and/or global developmental delay in the investigated patients. Results We identified four hemizygous sequence variants in the GABAA receptor subunit ε gene (GABRE), including one nonsense (NM_004961.3: c.399C>A, p.Tyr133*), two missense variants (NM_004961.3: c.664G>A, p.Glu222Lys; NM_004961.3: c.1045G>A, p.Val349Ile), and one variant affecting the translation initiation codon (NM_004961.3: c.1A>G, p.Met1?) in four unrelated families. Conclusion Our clinical and molecular genetic findings suggest that GABRE is a likely candidate gene for epilepsy. Nevertheless, functional studies are necessary to better understand pathogenicity of the GABRE‐mutations and their associations with epileptic phenotypes.
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Affiliation(s)
- Fenja Markus
- Junior Research Group, Genetics of Childhood Brain Malformations, Faculty VI-School of Medicine and Health Sciences, University of Oldenburg, Oldenburg, Germany.,Human Genetics, Faculty VI-School of Medicine and Health Sciences, University of Oldenburg, Oldenburg, Germany
| | - Chloé Angelini
- Service de Génétique médicale, CHU de Bordeaux, Bordeaux, France
| | | | - Gabrielle Rudolf
- CNRS U7104, INSERM U1258, Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France.,Service de Neurologie, Centre de Références des Maladies Neurogénétique Rares, Hôpitaux Universitaires de Strasbourg, Strasbourg, France
| | - Gaetan Lesca
- Genetics department, Lyon University Hospital and University of Lyon, Lyon, France
| | - Cyril Goizet
- Service de Génétique médicale, CHU de Bordeaux, Bordeaux, France.,CNRS U7104, INSERM U1258, Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France
| | - Eulalie Lasseaux
- Service de Génétique médicale, CHU de Bordeaux, Bordeaux, France
| | - Benoit Arveiler
- Service de Génétique médicale, CHU de Bordeaux, Bordeaux, France
| | - Marjon van Slegtenhorst
- Department of Clinical Genetics, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | - Alice S Brooks
- Department of Clinical Genetics, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | - Rami Abou Jamra
- Institute of Human Genetics, University Medical Center Leipzig, Leipzig, Germany
| | | | - John Neidhardt
- Human Genetics, Faculty VI-School of Medicine and Health Sciences, University of Oldenburg, Oldenburg, Germany.,Research Center Neurosensory Science, University of Oldenburg, Oldenburg, Germany
| | - Marta Owczarek-Lipska
- Junior Research Group, Genetics of Childhood Brain Malformations, Faculty VI-School of Medicine and Health Sciences, University of Oldenburg, Oldenburg, Germany.,Human Genetics, Faculty VI-School of Medicine and Health Sciences, University of Oldenburg, Oldenburg, Germany
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13
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Chow CY, Absalom N, Biggs K, King GF, Ma L. Venom-derived modulators of epilepsy-related ion channels. Biochem Pharmacol 2020; 181:114043. [PMID: 32445870 DOI: 10.1016/j.bcp.2020.114043] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Accepted: 05/18/2020] [Indexed: 12/18/2022]
Abstract
Epilepsy is characterised by spontaneous recurrent seizures that are caused by an imbalance between neuronal excitability and inhibition. Since ion channels play fundamental roles in the generation and propagation of action potentials as well as neurotransmitter release at a subset of excitatory and inhibitory synapses, their dysfunction has been linked to a wide variety of epilepsies. Indeed, these unique proteins are the major biological targets for antiepileptic drugs. Selective targeting of a specific ion channel subtype remains challenging for small molecules, due to the high level of homology among members of the same channel family. As a consequence, there is a growing trend to target ion channels with biologics. Venoms are the best known natural source of ion channel modulators, and venom peptides are increasingly recognised as potential therapeutics due to their high selectivity and potency gained through millions of years of evolutionary selection pressure. Here we describe the major ion channel families involved in the pathogenesis of various types of epilepsy, including voltage-gated Na+, K+, Ca2+ channels, Cys-loop receptors, ionotropic glutamate receptors and P2X receptors, and currently available venom-derived peptides that target these channel proteins. Although only a small number of venom peptides have successfully progressed to the clinic, there is reason to be optimistic about their development as antiepileptic drugs, notwithstanding the challenges associated with development of any class of peptide drug.
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Affiliation(s)
- Chun Yuen Chow
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Nathan Absalom
- Brain and Mind Centre, School of Pharmacy, Faculty of Health and Medicine, The University of Sydney, Sydney, NSW 2050, Australia
| | - Kimberley Biggs
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Glenn F King
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia.
| | - Linlin Ma
- Griffith Institute for Drug Discovery, Griffith University, Nathan, QLD 4111, Australia.
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14
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Velíšek L, Velíšková J. Modeling epileptic spasms during infancy: Are we heading for the treatment yet? Pharmacol Ther 2020; 212:107578. [PMID: 32417271 DOI: 10.1016/j.pharmthera.2020.107578] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Accepted: 05/07/2020] [Indexed: 12/22/2022]
Abstract
Infantile spasms (IS or epileptic spasms during infancy) were first described by Dr. William James West (aka West syndrome) in his own son in 1841. While rare by definition (occurring in 1 per 3200-3400 live births), IS represent a major social and treatment burden. The etiology of IS varies - there are many (>200) different known pathologies resulting in IS and still in about one third of cases there is no obvious reason. With the advancement of genetic analysis, role of certain genes (such as ARX or CDKL5 and others) in IS appears to be important. Current treatment strategies with incomplete efficacy and serious potential adverse effects include adrenocorticotropin (ACTH), corticosteroids (prednisone, prednisolone) and vigabatrin, more recently also a combination of hormones and vigabatrin. Second line treatments include pyridoxine (vitamin B6) and ketogenic diet. Additional treatment approaches use rapamycin, cannabidiol, valproic acid and other anti-seizure medications. Efficacy of these second line medications is variable but usually inferior to hormonal treatments and vigabatrin. Thus, new and effective models of this devastating condition are required for the search of additional treatment options as well as for better understanding the mechanisms of IS. Currently, eight models of IS are reviewed along with the ideas and mechanisms behind these models, drugs tested using the models and their efficacy and usefulness. Etiological variety of IS is somewhat reflected in the variety of the models. However, it seems that for finding precise personalized approaches, this variety is necessary as there is no "one-size-fits-all" approach possible for both IS in particular and epilepsy in general.
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Affiliation(s)
- Libor Velíšek
- Departments of Cell Biology & Anatomy, New York Medical College, Valhalla, NY, USA; Departments of Pediatrics, New York Medical College, Valhalla, NY, USA; Departments of Neurology, New York Medical College, Valhalla, NY, USA.
| | - Jana Velíšková
- Departments of Cell Biology & Anatomy, New York Medical College, Valhalla, NY, USA; Departments of Neurology, New York Medical College, Valhalla, NY, USA; Departments of Obstetrics & Gynecology, New York Medical College, Valhalla, NY, USA
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15
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GABRG2 Deletion Linked to Genetic Epilepsy with Febrile Seizures Plus Affects the Expression of GABA A Receptor Subunits and Other Genes at Different Temperatures. Neuroscience 2020; 438:116-136. [PMID: 32418750 DOI: 10.1016/j.neuroscience.2020.04.049] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Revised: 04/29/2020] [Accepted: 04/30/2020] [Indexed: 12/11/2022]
Abstract
Mutations in γ-aminobutyric acid A receptor (GABAA) subunits and sodium channel genes, especially GABRG2 and SCN1A, have been reported to be associated with febrile seizures (FS) and genetic epilepsy with febrile seizures plus (GEFS+). GEFS+ is a well-known family of epileptic syndrome with autosomal dominant inheritance in children. Its most common phenotypes are febrile seizures often with accessory afebrile generalized tonic-clonic seizures, febrile seizures plus (FS+), severe epileptic encephalopathy, as well as other types of generalized or localization-related seizures. However, the pathogenesis of febrile seizures remains largely unknown. Here, we generated a GABRG2 gene knockout cell line (HT22GABRG2KO) by applying the CRISPR/Cas9-mediated genomic deletion in HT-22 mouse hippocampal neuronal cell line to explore the function of GABRG2 in vitro. With mRNA-seq, we found significant changes in the expression profiles of several epilepsy-related genes when GABRG2 was knockout, some of them showing temperature-induced changes as well. Kyoto Encyclopedia Gene and Genomic (KEGG) analysis revealed a significant alteration in the MAPK and PI3K-Akt signaling pathways. We also observed an up-regulation of the matrix metalloproteinases (MMPs) family after GABRG2 knockout. Furthermore, the significant decrease in expression of GABRA1 and CACNA1A (but not others) with an increase in temperature is a novel finding. In summary, mutations in the GABAA receptor can lead to a decrease in numbers of receptors, which may cause the impairment of GABAergic pathway signaling. This data has been the first time to reveal that GABRG2 mutations would affect the function of other genes, and based on this finding we hope this work would also provide a new direction for the research of GABRG2 in GEFS+. It also may provide a molecular basis for the severity of epilepsy, and guide the clinical medication for the treatment of the epilepsy focused on the function on GABAA receptors, which, might be a new strategy for genetic diagnosis and targeted treatment of epilepsy.
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16
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Maljevic S, Keren B, Aung YH, Forster IC, Mignot C, Buratti J, Lafitte A, Freihuber C, Rodan LH, Bergin A, Hubert L, Poirier K, Munnich A, Besmond C, Hauser N, Miller R, McWalter K, Nabbout R, Héron D, Leguern E, Depienne C, Petrou S, Nava C. Novel GABRA2 variants in epileptic encephalopathy and intellectual disability with seizures. Brain 2020; 142:e15. [PMID: 31032849 DOI: 10.1093/brain/awz079] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Snezana Maljevic
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, VIC, Australia
| | - Boris Keren
- APHP, Hôpital Pitié-Salpêtrière, Département de Génétique, Centre de Reference Déficience Intellectuelle de Causes Rares, GRC UPMC «Déficience Intellectuelle et Autisme», Paris, France
| | - Ye Htet Aung
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, VIC, Australia
| | - Ian C Forster
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, VIC, Australia
| | - Cyril Mignot
- APHP, Hôpital Pitié-Salpêtrière, Département de Génétique, Centre de Reference Déficience Intellectuelle de Causes Rares, GRC UPMC «Déficience Intellectuelle et Autisme», Paris, France.,Sorbonne Universités, Institut du Cerveau et de la Moelle épinière, ICM, Inserm U1127, CNRS UMR 7225, F-75013, Paris, France
| | - Julien Buratti
- APHP, Hôpital Pitié-Salpêtrière, Département de Génétique, Centre de Reference Déficience Intellectuelle de Causes Rares, GRC UPMC «Déficience Intellectuelle et Autisme», Paris, France
| | - Aurélie Lafitte
- APHP, Hôpital Pitié-Salpêtrière, Département de Génétique, Centre de Reference Déficience Intellectuelle de Causes Rares, GRC UPMC «Déficience Intellectuelle et Autisme», Paris, France
| | - Cécile Freihuber
- AP-HP, Hôpital Trousseau, Service de Neuropédiatrie, Paris, France
| | - Lance H Rodan
- Division of Genetics and Genomics, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA.,Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Ann Bergin
- Division of Epilepsy and Clinical Neurophysiology, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Laurence Hubert
- INSERM UMR 1163, Translational Genetics Lab., Paris-Descartes University, Imagine Institute, Paris, France
| | - Karine Poirier
- INSERM UMR 1163, Translational Genetics Lab., Paris-Descartes University, Imagine Institute, Paris, France
| | - Arnold Munnich
- INSERM UMR 1163, Translational Genetics Lab., Paris-Descartes University, Imagine Institute, Paris, France
| | - Claude Besmond
- INSERM UMR 1163, Translational Genetics Lab., Paris-Descartes University, Imagine Institute, Paris, France
| | - Natalie Hauser
- Inova Health System, Inova Translational Medicine Institute, Falls Church, VA, USA
| | - Rebecca Miller
- Inova Health System, Inova Translational Medicine Institute, Falls Church, VA, USA
| | | | - Rima Nabbout
- APHP, Hôpital Necker Enfants Malades, Centre de référence épilepsies rares, Service de Neurologie pédiatrique, Paris, France
| | - Delphine Héron
- APHP, Hôpital Pitié-Salpêtrière, Département de Génétique, Centre de Reference Déficience Intellectuelle de Causes Rares, GRC UPMC «Déficience Intellectuelle et Autisme», Paris, France
| | - Eric Leguern
- APHP, Hôpital Pitié-Salpêtrière, Département de Génétique, Centre de Reference Déficience Intellectuelle de Causes Rares, GRC UPMC «Déficience Intellectuelle et Autisme», Paris, France.,Sorbonne Universités, Institut du Cerveau et de la Moelle épinière, ICM, Inserm U1127, CNRS UMR 7225, F-75013, Paris, France
| | - Christel Depienne
- Sorbonne Universités, Institut du Cerveau et de la Moelle épinière, ICM, Inserm U1127, CNRS UMR 7225, F-75013, Paris, France.,Institute of Human Genetics, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | - Steven Petrou
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, VIC, Australia
| | - Caroline Nava
- APHP, Hôpital Pitié-Salpêtrière, Département de Génétique, Centre de Reference Déficience Intellectuelle de Causes Rares, GRC UPMC «Déficience Intellectuelle et Autisme», Paris, France.,Sorbonne Universités, Institut du Cerveau et de la Moelle épinière, ICM, Inserm U1127, CNRS UMR 7225, F-75013, Paris, France
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17
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Arya P, Wilson TE, Parent JJ, Ware SM, Breman AM, Helm BM. An adult female with 5q34-q35.2 deletion: A rare syndromic presentation of left ventricular non-compaction and congenital heart disease. Eur J Med Genet 2020; 63:103797. [DOI: 10.1016/j.ejmg.2019.103797] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Revised: 09/12/2019] [Accepted: 10/20/2019] [Indexed: 12/23/2022]
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18
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Cárdenas-Rodríguez N, Carmona-Aparicio L, Pérez-Lozano DL, Ortega-Cuellar D, Gómez-Manzo S, Ignacio-Mejía I. Genetic variations associated with pharmacoresistant epilepsy (Review). Mol Med Rep 2020; 21:1685-1701. [PMID: 32319641 PMCID: PMC7057824 DOI: 10.3892/mmr.2020.10999] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Accepted: 01/16/2020] [Indexed: 12/13/2022] Open
Abstract
Epilepsy is a common, serious neurological disorder worldwide. Although this disease can be successfully treated in most cases, not all patients respond favorably to medical treatments, which can lead to pharmacoresistant epilepsy. Drug-resistant epilepsy can be caused by a number of mechanisms that may involve environmental and genetic factors, as well as disease- and drug-related factors. In recent years, numerous studies have demonstrated that genetic variation is involved in the drug resistance of epilepsy, especially genetic variations found in drug resistance-related genes, including the voltage-dependent sodium and potassium channels genes, and the metabolizer of endogenous and xenobiotic substances genes. The present review aimed to highlight the genetic variants that are involved in the regulation of drug resistance in epilepsy; a comprehensive understanding of the role of genetic variation in drug resistance will help us develop improved strategies to regulate drug resistance efficiently and determine the pathophysiological processes that underlie this common human neurological disease.
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Affiliation(s)
- Noemí Cárdenas-Rodríguez
- Laboratory of Neuroscience, National Institute of Pediatrics, Ministry of Health, Coyoacán, Mexico City 04530, Mexico
| | - Liliana Carmona-Aparicio
- Laboratory of Neuroscience, National Institute of Pediatrics, Ministry of Health, Coyoacán, Mexico City 04530, Mexico
| | - Diana L Pérez-Lozano
- Laboratory of Neuroscience, National Institute of Pediatrics, Ministry of Health, Coyoacán, Mexico City 04530, Mexico
| | - Daniel Ortega-Cuellar
- Laboratory of Experimental Nutrition, National Institute of Pediatrics, Ministry of Health, Coyoacán, Mexico City 04530, Mexico
| | - Saúl Gómez-Manzo
- Laboratory of Genetic Biochemistry, National Institute of Pediatrics, Ministry of Health, Coyoacán, Mexico City 04530, Mexico
| | - Iván Ignacio-Mejía
- Laboratory of Translational Medicine, Military School of Health Graduates, Lomas de Sotelo, Militar, Mexico City 11200, Mexico
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19
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Papandreou A, Danti FR, Spaull R, Leuzzi V, Mctague A, Kurian MA. The expanding spectrum of movement disorders in genetic epilepsies. Dev Med Child Neurol 2020; 62:178-191. [PMID: 31784983 DOI: 10.1111/dmcn.14407] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 03/01/2019] [Indexed: 12/27/2022]
Abstract
An ever-increasing number of neurogenetic conditions presenting with both epilepsy and atypical movements are now recognized. These disorders within the 'genetic epilepsy-dyskinesia' spectrum are clinically and genetically heterogeneous. Increased clinical awareness is therefore necessary for a rational diagnostic approach. Furthermore, careful interpretation of genetic results is key to establishing the correct diagnosis and initiating disease-specific management strategies in a timely fashion. In this review we describe the spectrum of movement disorders associated with genetically determined epilepsies. We also propose diagnostic strategies and putative pathogenic mechanisms causing these complex syndromes associated with both seizures and atypical motor control. WHAT THIS PAPER ADDS: Implicated genes encode proteins with very diverse functions. Pathophysiological mechanisms by which epilepsy and movement disorder phenotypes manifest are often not clear. Early diagnosis of treatable disorders is essential and next generation sequencing may be required.
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Affiliation(s)
- Apostolos Papandreou
- Molecular Neurosciences, Developmental Neurosciences Programme, UCL Great Ormond Street Institute of Child Health, London, UK
- Department of Neurology, Great Ormond Street Hospital, London, UK
| | - Federica Rachele Danti
- Molecular Neurosciences, Developmental Neurosciences Programme, UCL Great Ormond Street Institute of Child Health, London, UK
- Department of Human Neuroscience, Unit of Child Neurology and Psychiatry, Sapienza University of Rome, Rome, Italy
| | - Robert Spaull
- Department of Paediatric Neurology, Bristol Royal Hospital for Children, Bristol, UK
- Bristol Medical School, University of Bristol, Bristol, UK
| | - Vincenzo Leuzzi
- Department of Human Neuroscience, Unit of Child Neurology and Psychiatry, Sapienza University of Rome, Rome, Italy
| | - Amy Mctague
- Molecular Neurosciences, Developmental Neurosciences Programme, UCL Great Ormond Street Institute of Child Health, London, UK
- Department of Neurology, Great Ormond Street Hospital, London, UK
| | - Manju A Kurian
- Molecular Neurosciences, Developmental Neurosciences Programme, UCL Great Ormond Street Institute of Child Health, London, UK
- Department of Neurology, Great Ormond Street Hospital, London, UK
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20
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Copy number variation analysis in 83 children with early-onset developmental and epileptic encephalopathy after targeted resequencing of a 109-epilepsy gene panel. J Hum Genet 2019; 64:1097-1106. [DOI: 10.1038/s10038-019-0661-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Revised: 07/23/2019] [Accepted: 08/11/2019] [Indexed: 12/13/2022]
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21
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Goto A, Ishii A, Shibata M, Ihara Y, Cooper EC, Hirose S. Characteristics of
KCNQ
2
variants causing either benign neonatal epilepsy or developmental and epileptic encephalopathy. Epilepsia 2019; 60:1870-1880. [DOI: 10.1111/epi.16314] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Revised: 07/23/2019] [Accepted: 07/23/2019] [Indexed: 12/01/2022]
Affiliation(s)
- Ayako Goto
- Department of Pediatrics School of Medicine Fukuoka University Fukuoka Japan
| | - Atsushi Ishii
- Department of Pediatrics School of Medicine Fukuoka University Fukuoka Japan
| | - Mami Shibata
- Central Research Institute for the Molecular Pathomechanisms of Epilepsy Fukuoka University Fukuoka Japan
| | - Yukiko Ihara
- Department of Pediatrics School of Medicine Fukuoka University Fukuoka Japan
| | - Edward C. Cooper
- Department of Neurology Baylor College of Medicine Houston Texas
| | - Shinichi Hirose
- Department of Pediatrics School of Medicine Fukuoka University Fukuoka Japan
- Central Research Institute for the Molecular Pathomechanisms of Epilepsy Fukuoka University Fukuoka Japan
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22
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Muir AM, Myers CT, Nguyen NT, Saykally J, Craiu D, De Jonghe P, Helbig I, Hoffman-Zacharska D, Guerrini R, Lehesjoki AE, Marini C, Møller RS, Serratosa J, Štěrbová K, Striano P, von Spiczak S, Weckhuysen S, Mefford HC. Genetic heterogeneity in infantile spasms. Epilepsy Res 2019; 156:106181. [PMID: 31394400 DOI: 10.1016/j.eplepsyres.2019.106181] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Accepted: 07/27/2019] [Indexed: 11/25/2022]
Abstract
Infantile spasms (IS) is a developmental and epileptic encephalopathy with heterogeneous etiologies including many genetic causes. Genetic studies have identified pathogenic variants in over 30 genes as causes of IS. Many of these genetic causes are extremely rare, with only one reported incidence in an individual with IS. To better understand the genetic landscape of IS, we used targeted sequencing to screen 42 candidate IS genes and 53 established developmental and epileptic encephalopathy genes in 92 individual with IS. We identified a genetic diagnosis for 7.6% of our cohort, including pathogenic variants in KCNB1 (n = 2), GNAO1 (n = 1), STXBP1 (n = 1), SLC35A2 (n = 1), TBL1XR1 (n = 1), and KIF1A (n = 1). Our data emphasize the genetic heterogeneity of IS and will inform the diagnosis and management of individuals with this devastating disorder.
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Affiliation(s)
- Alison M Muir
- Division of Genetic Medicine, Department of Pediatrics, University of Washington, Seattle, WA 98195, USA
| | - Candace T Myers
- Division of Genetic Medicine, Department of Pediatrics, University of Washington, Seattle, WA 98195, USA
| | - Nancy T Nguyen
- Division of Genetic Medicine, Department of Pediatrics, University of Washington, Seattle, WA 98195, USA
| | - Julia Saykally
- Division of Genetic Medicine, Department of Pediatrics, University of Washington, Seattle, WA 98195, USA
| | - Dana Craiu
- Department of Clinical Neurosciences and Pediatric Neurology Clinic, "Carol Davila" University of Medicine, Al. Obregia Hospital, Bucharest 050474, Romania; Pediatric Neurology Clinic Alexandru Obregia Hospital Bucharest Romania
| | - Peter De Jonghe
- Neurogenetics Group, Center for Molecular Neurology, VIB, University of Antwerp, Antwerp 2610, Belgium; Institute Born Bunge, University of Antwerp, Antwerp 2610, Belgium; Department of Neurology, Antwerp University Hospital, Antwerp 2650, Belgium
| | - Ingo Helbig
- Division of Neurology, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA; Department of Neuropediatrics, Christian-Albrechts-University Kiel and University Hospital Schleswig-Holstein, Campus Kiel 24105, Germany
| | - Dorota Hoffman-Zacharska
- Department of Medical Genetics, Institute of Mother and Child, Warsaw, Poland; Institute of Genetics and Biotechnology, Warsaw University, Warsaw, Poland
| | - Renzo Guerrini
- Pediatric Neurology, Neurogenetics, and Neurobiology Unit and Laboratories, A. Meyer Children's Hospital, University of Florence, Florence 50139, Italy
| | - Anna-Elina Lehesjoki
- Folkhälsan Research Center and Medical Faculty, University of Helsinki, Helsinki 00290, Finland
| | - Carla Marini
- Pediatric Neurology, Neurogenetics, and Neurobiology Unit and Laboratories, A. Meyer Children's Hospital, University of Florence, Florence 50139, Italy
| | - Rikke S Møller
- Danish Epilepsy Centre, Dianalund 4293, Denmark; Institute for Regional Health research, University of Southern Denmark, Odense 5230, Denmark
| | - Jose Serratosa
- Department of Neurology, Neurology Lab and Epilepsy Unit, IIS-Fundación Jiménez Díaz UAM and CIBERER, Madrid 28040, Spain
| | - Katalin Štěrbová
- Child Neurology Department, 2nd Faculty of Medicine, Charles University and University Hospital Motol, Prague 150 06, Czech Republic
| | - Pasquale Striano
- Pediatric Neurology and Muscular Diseases Unit, IRCCS Istituto "G. Gaslini", Genova 16147, Italy; Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genova, Genova 16132, Italy
| | - Sarah von Spiczak
- Department of Neuropediatrics, Christian-Albrechts-University Kiel and University Hospital Schleswig-Holstein, Campus Kiel 24105, Germany; Northern German Epilepsy Center for Children and Adolescents, Schwentinental-Raisdorf, 24223, Germany
| | - Sarah Weckhuysen
- Neurogenetics Group, Center for Molecular Neurology, VIB, University of Antwerp, Antwerp 2610, Belgium; Institute Born Bunge, University of Antwerp, Antwerp 2610, Belgium; Department of Neurology, Antwerp University Hospital, Antwerp 2650, Belgium
| | - Heather C Mefford
- Division of Genetic Medicine, Department of Pediatrics, University of Washington, Seattle, WA 98195, USA.
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23
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Pathogenic Variants in STXBP1 and in Genes for GABAa Receptor Subunities Cause Atypical Rett/Rett-like Phenotypes. Int J Mol Sci 2019; 20:ijms20153621. [PMID: 31344879 PMCID: PMC6696386 DOI: 10.3390/ijms20153621] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Revised: 07/16/2019] [Accepted: 07/19/2019] [Indexed: 12/19/2022] Open
Abstract
Rett syndrome (RTT) is a neurodevelopmental disorder, affecting 1 in 10,000 girls. Intellectual disability, loss of speech and hand skills with stereotypies, seizures and ataxia are recurrent features. Stringent diagnostic criteria distinguish classical Rett, caused by a MECP2 pathogenic variant in 95% of cases, from atypical girls, 40-73% carrying MECP2 variants, and rarely CDKL5 and FOXG1 alterations. A large fraction of atypical and RTT-like patients remain without genetic cause. Next Generation Sequencing (NGS) targeted to multigene panels/Whole Exome Sequencing (WES) in 137 girls suspected for RTT led to the identification of a de novo variant in STXBP1 gene in four atypical RTT and two RTT-like girls. De novo pathogenic variants-one in GABRB2 and, for first time, one in GABRG2-were disclosed in classic and atypical RTT patients. Interestingly, the GABRG2 variant occurred at low rate percentage in blood and buccal swabs, reinforcing the relevance of mosaicism in neurological disorders. We confirm the role of STXBP1 in atypical RTT/RTT-like patients if early psychomotor delay and epilepsy before 2 years of age are observed, indicating its inclusion in the RTT diagnostic panel. Lastly, we report pathogenic variants in Gamma-aminobutyric acid-A (GABAa) receptors as a cause of atypical/classic RTT phenotype, in accordance with the deregulation of GABAergic pathway observed in MECP2 defective in vitro and in vivo models.
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24
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Hernandez CC, XiangWei W, Hu N, Shen D, Shen W, Lagrange AH, Zhang Y, Dai L, Ding C, Sun Z, Hu J, Zhu H, Jiang Y, Macdonald RL. Altered inhibitory synapses in de novo GABRA5 and GABRA1 mutations associated with early onset epileptic encephalopathies. Brain 2019; 142:1938-1954. [PMID: 31056671 PMCID: PMC6598634 DOI: 10.1093/brain/awz123] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Revised: 02/20/2019] [Accepted: 03/07/2019] [Indexed: 12/22/2022] Open
Abstract
We performed next generation sequencing on 1696 patients with epilepsy and intellectual disability using a gene panel with 480 epilepsy-related genes including all GABAA receptor subunit genes (GABRs), and we identified six de novo GABR mutations, two novel GABRA5 mutations (c.880G>T, p.V294F and c.1238C>T, p.S413F), two novel GABRA1 mutations (c.778C>T, p.P260S and c.887T>C, p.L296S/c.944G>T, p.W315L) and two known GABRA1 mutations (c.335G>A, p.R112Q and c.343A>G, p.N115D) in six patients with intractable early onset epileptic encephalopathy. The α5(V294F and S413F) and α1(P260S and L296S/W315L) subunit residue substitutions were all in transmembrane domains, while the α1(R112Q and N115R) subunit residue substitutions were in the N-terminal GABA binding domain. Using multidisciplinary approaches, we compared effects of mutant GABAA receptor α5 and α1 subunits on the properties of recombinant α5β3γ2 and α1β3γ2 GABAA receptors in both neuronal and non-neuronal cells and characterized their effects on receptor clustering, biogenesis and channel function. GABAA receptors containing mutant α5 and α1 subunits all had reduced cell surface and total cell expression with altered endoplasmic reticulum processing, impaired synaptic clustering, reduced GABAA receptor function and decreased GABA binding potency. Our study identified GABRA5 as a causative gene for early onset epileptic encephalopathy and expands the mutant GABRA1 phenotypic spectrum, supporting growing evidence that defects in GABAergic neurotransmission contribute to early onset epileptic encephalopathy phenotypes.
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Affiliation(s)
- Ciria C Hernandez
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN, USA
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
| | - Wenshu XiangWei
- Department of Pediatrics and Pediatric Epilepsy Center, Peking University First Hospital, Beijing, China
- Center of Epilepsy, Beijing Institute for Brain Disorders, Beijing, China
| | - Ningning Hu
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Dingding Shen
- The Graduate Program of Neuroscience, Vanderbilt University, Nashville, TN, USA
- Department of Neurology, Rui Jin Hospital, Shanghai Jiao Tong University, School of Medicine. Shanghai, China
| | - Wangzhen Shen
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Andre H Lagrange
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN, USA
- Department of Pharmacology and Molecular Physiology and Biophysics, Vanderbilt University, and the Veterans Affairs Tennessee Valley Healthcare System, Nashville, TN, USA
| | - Yujia Zhang
- Department of Neurology, Beijing Children’s Hospital, Capital Medical University, National Center for Children’s Health, Beijing, China
| | - Lifang Dai
- Department of Neurology, Beijing Children’s Hospital, Capital Medical University, National Center for Children’s Health, Beijing, China
| | - Changhong Ding
- Department of Neurology, Beijing Children’s Hospital, Capital Medical University, National Center for Children’s Health, Beijing, China
| | - Zhaohui Sun
- Epilepsy center of Yuquan Hospital, Tsinghua University, Beijing, China
| | - Jiasheng Hu
- Department of Neurology, Wuhan Children’s Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Hongmin Zhu
- Department of Neurology, Wuhan Children’s Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yuwu Jiang
- Department of Pediatrics and Pediatric Epilepsy Center, Peking University First Hospital, Beijing, China
- Center of Epilepsy, Beijing Institute for Brain Disorders, Beijing, China
| | - Robert L Macdonald
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN, USA
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25
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Sequeira A, Shen K, Gottlieb A, Limon A. Human brain transcriptome analysis finds region- and subject-specific expression signatures of GABA AR subunits. Commun Biol 2019; 2:153. [PMID: 31069263 PMCID: PMC6494906 DOI: 10.1038/s42003-019-0413-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Accepted: 04/03/2019] [Indexed: 11/19/2022] Open
Abstract
Altered expression of GABA receptors (GABAARs) has been implicated in neurological and psychiatric disorders, but limited information about region-specific GABAAR subunit expression in healthy human brains, heteromeric assembly of major isoforms, and their collective organization across healthy individuals, are major roadblocks to understanding their role in non-physiological states. Here, by using microarray and RNA-Seq datasets-from single cell nuclei to global brain expression-from the Allen Institute, we find that transcriptional expression of GABAAR subunits is anatomically organized according to their neurodevelopmental origin. The data show a combination of complementary and mutually-exclusive expression patterns that delineate major isoforms, and which is highly stereotypical across brains from control donors. We summarize the region-specific signature of GABAR subunits per subject and its variability in a control population sample that can be used as a reference for remodeling changes during homeostatic rearrangements of GABAAR subunits after physiological, pharmacological or pathological challenges.
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Affiliation(s)
- Adolfo Sequeira
- Department of Psychiatry and Human Behavior, School of Medicine, University of California Irvine, Irvine, CA USA
| | - Kevin Shen
- Department of Neurology, Mitchel Center for Neurodegenerative Diseases, School of Medicine, University of Texas Medical Branch, Galveston, TX USA
| | - Assaf Gottlieb
- School of Biomedical Informatics, The University of Texas Health Science Center at Houston, Houston, TX USA
| | - Agenor Limon
- Department of Neurology, Mitchel Center for Neurodegenerative Diseases, School of Medicine, University of Texas Medical Branch, Galveston, TX USA
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27
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Mele M, Costa RO, Duarte CB. Alterations in GABA A-Receptor Trafficking and Synaptic Dysfunction in Brain Disorders. Front Cell Neurosci 2019; 13:77. [PMID: 30899215 PMCID: PMC6416223 DOI: 10.3389/fncel.2019.00077] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Accepted: 02/15/2019] [Indexed: 12/12/2022] Open
Abstract
GABAA receptors (GABAAR) are the major players in fast inhibitory neurotransmission in the central nervous system (CNS). Regulation of GABAAR trafficking and the control of their surface expression play important roles in the modulation of the strength of synaptic inhibition. Different pieces of evidence show that alterations in the surface distribution of GABAAR and dysregulation of their turnover impair the activity of inhibitory synapses. A diminished efficacy of inhibitory neurotransmission affects the excitatory/inhibitory balance and is a common feature of various disorders of the CNS characterized by an increased excitability of neuronal networks. The synaptic pool of GABAAR is mainly controlled through regulation of internalization, recycling and lateral diffusion of the receptors. Under physiological condition these mechanisms are finely coordinated to define the strength of GABAergic synapses. In this review article, we focus on the alteration in GABAAR trafficking with an impact on the function of inhibitory synapses in various disorders of the CNS. In particular we discuss how similar molecular mechanisms affecting the synaptic distribution of GABAAR and consequently the excitatory/inhibitory balance may be associated with a wide diversity of pathologies of the CNS, from psychiatric disorders to acute alterations leading to neuronal death. A better understanding of the cellular and molecular mechanisms that contribute to the impairment of GABAergic neurotransmission in these disorders, in particular the alterations in GABAAR trafficking and surface distribution, may lead to the identification of new pharmacological targets and to the development of novel therapeutic strategies.
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Affiliation(s)
- Miranda Mele
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.,Institute for Interdisciplinary Research, University of Coimbra, Coimbra, Portugal
| | - Rui O Costa
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.,Institute for Interdisciplinary Research, University of Coimbra, Coimbra, Portugal
| | - Carlos B Duarte
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.,Department of Life Sciences, University of Coimbra, Coimbra, Portugal
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28
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Hernandez CC, Macdonald RL. A structural look at GABA A receptor mutations linked to epilepsy syndromes. Brain Res 2019; 1714:234-247. [PMID: 30851244 DOI: 10.1016/j.brainres.2019.03.004] [Citation(s) in RCA: 58] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 02/25/2019] [Accepted: 03/06/2019] [Indexed: 12/12/2022]
Abstract
Understanding the genetic variation in GABAA receptor subunit genes (GABRs), GABRA1-6, GABRB1-3, GABRG1-3 and GABRD, in individuals affected by epilepsy may improve the diagnosis and treatment of epilepsy syndromes through identification of disease-associated variants. However, the lack of functional analysis and validation of many novel and previously reported familial and de novo mutations have made it challenging to address meaningful gene associations with epilepsy syndromes. GABAA receptors belong to the Cys-loop receptor family. Even though GABAA receptor mutant residues are widespread among different GABRs, their frequent occurrence in important structural domains that share common functional features suggests associations between structure and function.
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Affiliation(s)
- Ciria C Hernandez
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA.
| | - Robert L Macdonald
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN, USA
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29
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Butler KM, Moody OA, Schuler E, Coryell J, Alexander JJ, Jenkins A, Escayg A. De novo variants in GABRA2 and GABRA5 alter receptor function and contribute to early-onset epilepsy. Brain 2018; 141:2392-2405. [PMID: 29961870 PMCID: PMC6061692 DOI: 10.1093/brain/awy171] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Revised: 04/02/2018] [Accepted: 05/04/2018] [Indexed: 01/19/2023] Open
Abstract
GABAA receptors are ligand-gated anion channels that are important regulators of neuronal inhibition. Mutations in several genes encoding receptor subunits have been identified in patients with various types of epilepsy, ranging from mild febrile seizures to severe epileptic encephalopathy. Using whole-genome sequencing, we identified a novel de novo missense variant in GABRA5 (c.880G > C, p.V294L) in a patient with severe early-onset epilepsy and developmental delay. Targeted resequencing of 279 additional epilepsy patients identified 19 rare variants from nine GABAA receptor genes, including a novel de novo missense variant in GABRA2 (c.875C > A, p.T292K) and a recurrent missense variant in GABRB3 (c.902C > T, p.P301L). Patients with the GABRA2 and GABRB3 variants also presented with severe epilepsy and developmental delay. We evaluated the effects of the GABRA5, GABRA2 and GABRB3 missense variants on receptor function using whole-cell patch-clamp recordings from human embryonic kidney 293T cells expressing appropriate α, β and γ subunits. The GABRA5 p.V294L variant produced receptors that were 10-times more sensitive to GABA but had reduced maximal GABA-evoked current due to increased receptor desensitization. The GABRA2 p.T292K variant reduced channel expression and produced mutant channels that were tonically open, even in the absence of GABA. Receptors containing the GABRB3 p.P301L variant were less sensitive to GABA and produced less GABA-evoked current. These results provide the first functional evidence that de novo variants in the GABRA5 and GABRA2 genes contribute to early-onset epilepsy and developmental delay, and demonstrate that epilepsy can result from reduced neuronal inhibition via a wide range of alterations in GABAA receptor function.
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Affiliation(s)
- Kameryn M Butler
- Department of Human Genetics, Emory University, Atlanta, Georgia, 30322, USA
- Genetics and Molecular Biology Program, Graduate Division of Biological and Biomedical Sciences, Laney Graduate School, Emory University, Atlanta, Georgia, 30322, USA
| | - Olivia A Moody
- Departments of Anesthesiology and Pharmacology, Emory University, Atlanta, Georgia, 30322, USA
- Neuroscience Program, Graduate Division of Biological and Biomedical Sciences, Laney Graduate School, Emory University, Atlanta, Georgia, 30322, USA
| | - Elisabeth Schuler
- Department for Pediatric Metabolic Medicine and Neurology, University Children’s Hospital, Heidelberg, 69120, Germany
| | - Jason Coryell
- Departments of Pediatrics and Neurology, School of Medicine, Oregon Health & Sciences University, Portland, Oregon, 97239, USA
| | - John J Alexander
- Department of Human Genetics, Emory University, Atlanta, Georgia, 30322, USA
- EGL Genetics, Tucker, Georgia, 30084, USA
| | - Andrew Jenkins
- Departments of Anesthesiology and Pharmacology, Emory University, Atlanta, Georgia, 30322, USA
| | - Andrew Escayg
- Department of Human Genetics, Emory University, Atlanta, Georgia, 30322, USA
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Rare coding variants in genes encoding GABA A receptors in genetic generalised epilepsies: an exome-based case-control study. Lancet Neurol 2018; 17:699-708. [PMID: 30033060 DOI: 10.1016/s1474-4422(18)30215-1] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Revised: 05/17/2018] [Accepted: 05/29/2018] [Indexed: 12/20/2022]
Abstract
BACKGROUND Genetic generalised epilepsy is the most common type of inherited epilepsy. Despite a high concordance rate of 80% in monozygotic twins, the genetic background is still poorly understood. We aimed to investigate the burden of rare genetic variants in genetic generalised epilepsy. METHODS For this exome-based case-control study, we used three different genetic generalised epilepsy case cohorts and three independent control cohorts, all of European descent. Cases included in the study were clinically evaluated for genetic generalised epilepsy. Whole-exome sequencing was done for the discovery case cohort, a validation case cohort, and two independent control cohorts. The replication case cohort underwent targeted next-generation sequencing of the 19 known genes encoding subunits of GABAA receptors and was compared to the respective GABAA receptor variants of a third independent control cohort. Functional investigations were done with automated two-microelectrode voltage clamping in Xenopus laevis oocytes. FINDINGS Statistical comparison of 152 familial index cases with genetic generalised epilepsy in the discovery cohort to 549 ethnically matched controls suggested an enrichment of rare missense (Nonsyn) variants in the ensemble of 19 genes encoding GABAA receptors in cases (odds ratio [OR] 2·40 [95% CI 1·41-4·10]; pNonsyn=0·0014, adjusted pNonsyn=0·019). Enrichment for these genes was validated in a whole-exome sequencing cohort of 357 sporadic and familial genetic generalised epilepsy cases and 1485 independent controls (OR 1·46 [95% CI 1·05-2·03]; pNonsyn=0·0081, adjusted pNonsyn=0·016). Comparison of genes encoding GABAA receptors in the independent replication cohort of 583 familial and sporadic genetic generalised epilepsy index cases, based on candidate-gene panel sequencing, with a third independent control cohort of 635 controls confirmed the overall enrichment of rare missense variants for 15 GABAA receptor genes in cases compared with controls (OR 1·46 [95% CI 1·02-2·08]; pNonsyn=0·013, adjusted pNonsyn=0·027). Functional studies for two selected genes (GABRB2 and GABRA5) showed significant loss-of-function effects with reduced current amplitudes in four of seven tested variants compared with wild-type receptors. INTERPRETATION Functionally relevant variants in genes encoding GABAA receptor subunits constitute a significant risk factor for genetic generalised epilepsy. Examination of the role of specific gene groups and pathways can disentangle the complex genetic architecture of genetic generalised epilepsy. FUNDING EuroEPINOMICS (European Science Foundation through national funding organisations), Epicure and EpiPGX (Sixth Framework Programme and Seventh Framework Programme of the European Commission), Research Unit FOR2715 (German Research Foundation and Luxembourg National Research Fund).
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Li JQ, Yuan XZ, Li HY, Cao XP, Yu JT, Tan L, Chen WA. Genome-wide association study identifies two loci influencing plasma neurofilament light levels. BMC Med Genomics 2018; 11:47. [PMID: 29747637 PMCID: PMC5946407 DOI: 10.1186/s12920-018-0364-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Accepted: 05/01/2018] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Plasma neurofilament light (NFL) is a promising biomarker for Alzheimer disease (AD), which increases in the early stage of AD and is associated with the progression of AD. We performed a genome-wide association study (GWAS) of plasma NFL in Alzheimer's Disease Neuroimaging Initiative 1 (ADNI-1) cohort to identify novel variants associated with AD. METHODS This study included 179 cognitively healthy controls (HC), 176 patients with mild cognitive impairment (MCI), and 172 patients with AD. All subjects were restricted to non-Hispanic Caucasian derived from the ADNI cohort and met all quality control (QC) criteria. Association of plasma NFL with the genetic variants was assessed using PLINK with an additive genetic model, i.e.dose-dependent effect of the minor alleles. The influence of a genetic variant associated with plasma NFL (rs7943454) on brain structure was further assessed using PLINK with a linear regression model. RESULTS The minor allele (T) of rs7943454 in leucine zipper protein 2 gene (LUZP2) was associated with higher plasma NFL at suggestive levels (P = 1.39 × 10- 6) in a dose-dependent fashion. In contrast, the minor allele (G) of rs640476 near GABRB2 was associated with lower plasma NFL at suggestive levels (P = 6.71 × 10- 6) in a dose-dependent effect in all diagnostic groups except the MCI group. Furthermore, the minor allele (T) of rs7943454 within LUZP2 increased the onset risk of AD (odds ratio = 1.547, confidence interval 95% = 1.018-2.351) and was associated with atrophy of right middle temporal gyrus in the whole cohort in the longitudinal study (P = 0.0234). CONCLUSION GWAS found the associations of two single nucleotide polymorphisms (rs7943454 and rs640476) with plasma NFL at suggestive levels. Rs7943454 in LUZP2 was associated with the onset risk of AD and atrophy of right middle temporal gyrusin the whole cohort. Using an endophenotype-based approach, we identified rs7943454 as a new AD risk locus.
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Affiliation(s)
- Jie-Qiong Li
- Department of Neurology, Qingdao Municipal Hospital, Qingdao University, No.5 Donghai Middle Road, Qingdao, 266071, Shandong Province, China
| | - Xiang-Zhen Yuan
- Department of Neurology, Qingdao Municipal Hospital, Qingdao University, No.5 Donghai Middle Road, Qingdao, 266071, Shandong Province, China
| | - Hai-Yan Li
- Department of Neurology, Weihaiwei People's Hospital, Weihai, China
| | - Xi-Peng Cao
- Clinical Research Center, Qingdao Municipal Hospital, Qingdao University, Qingdao, China
| | - Jin-Tai Yu
- Department of Neurology, Qingdao Municipal Hospital, Qingdao University, No.5 Donghai Middle Road, Qingdao, 266071, Shandong Province, China. .,Clinical Research Center, Qingdao Municipal Hospital, Qingdao University, Qingdao, China.
| | - Lan Tan
- Department of Neurology, Qingdao Municipal Hospital, Qingdao University, No.5 Donghai Middle Road, Qingdao, 266071, Shandong Province, China. .,Clinical Research Center, Qingdao Municipal Hospital, Qingdao University, Qingdao, China.
| | - Wei-An Chen
- Department of Neurology, The First Affiliated Hospital of Wenzhou Medical University, Nanbaixiang Road, Wenzhou, 325000, Zhejiang Province, China.
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Orenstein N, Goldberg-Stern H, Straussberg R, Bazak L, Weisz Hubshman M, Kropach N, Gilad O, Scheuerman O, Dory Y, Kraus D, Tzur S, Magal N, Kilim Y, Shkalim Zemer V, Basel-Salmon L. A de novo GABRA2 missense mutation in severe early-onset epileptic encephalopathy with a choreiform movement disorder. Eur J Paediatr Neurol 2018; 22:516-524. [PMID: 29422393 DOI: 10.1016/j.ejpn.2017.12.017] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/28/2017] [Revised: 12/16/2017] [Accepted: 12/22/2017] [Indexed: 01/13/2023]
Abstract
BACKGROUND Early-onset epileptic encephalopathy (EOEE) is a severe convulsive disorder with a poor developmental prognosis. Although it has been associated with mutations in a number of genes, the fact that there is a large proportion of patients who remain undiagnosed suggests that there are many more still-unknown genetic causes of EOEE. Achieving a genetic diagnosis is important for understanding the biological basis of the disease, with its implications for treatment and family planning. METHODS Whole-exome sequencing was performed in a family of Ashkenazi Jewish origin in which a male infant was diagnosed with EOEE. There was no family history of a similar neurologic disease. The patient had extreme hypotonia, neonatal hypothermia, choreiform movements, and vision impairment in addition to the convulsive disorder. RESULTS A de novo heterozygous missense mutation, c.1003A > C, p.Asn335His, was identified in a conserved domain of GABRA2. GABRA2 encodes the α2 subunit of the GABAA receptor. CONCLUSIONS In the context of previous reports of an association of de novo mutations in genes encoding different subunits of the GABAA receptor (GABRB1, GABRA1, GABRG2, GABRB3) with autosomal dominant epileptic disorders, we conclude that a de novo mutation in GABRA2 is likely to cause autosomal dominant EOEE accompanied by a movement disorder and vision impairment.
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Affiliation(s)
- Naama Orenstein
- Pediatric Genetics Clinic, Schneider Children's Medical Center of Israel, Petach Tikva 4920235, Israel; Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel.
| | - Hadassa Goldberg-Stern
- Pediatric Genetics Clinic, Schneider Children's Medical Center of Israel, Petach Tikva 4920235, Israel; Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel; Pediatric Epilepsy Unit, Neurological Institute, Schneider Children's Medical Center of Israel, Petach Tikva 4920235, Israel.
| | - Rachel Straussberg
- Pediatric Genetics Clinic, Schneider Children's Medical Center of Israel, Petach Tikva 4920235, Israel; Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel; Neurogenetic Service, Neurological Institute, Schneider Children's Medical Center of Israel, Petach Tikva 4920235, Israel.
| | - Lily Bazak
- Raphael Recanati Genetics Institute, Rabin Medical Center- Beilinson Hospital, Petach Tikva 4941492, Israel; Mina and Everard Goodman Faculty of Life Science, Bar Ilan University, Ramat Gan 5290002, Israel; Felsenstein Medical Research Center, Rabin Medical Center, Petach Tikva 4941492, Israel.
| | - Monika Weisz Hubshman
- Pediatric Genetics Clinic, Schneider Children's Medical Center of Israel, Petach Tikva 4920235, Israel; Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel; Raphael Recanati Genetics Institute, Rabin Medical Center- Beilinson Hospital, Petach Tikva 4941492, Israel; Felsenstein Medical Research Center, Rabin Medical Center, Petach Tikva 4941492, Israel.
| | - Nesia Kropach
- Pediatric Genetics Clinic, Schneider Children's Medical Center of Israel, Petach Tikva 4920235, Israel; Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel.
| | - Oded Gilad
- Pediatric Genetics Clinic, Schneider Children's Medical Center of Israel, Petach Tikva 4920235, Israel; Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel.
| | - Oded Scheuerman
- Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel; Department of Pediatrics B, Schneider Children's Medical Center of Israel, Petach Tikva 4920235, Israel.
| | - Yahav Dory
- Pediatric Genetics Clinic, Schneider Children's Medical Center of Israel, Petach Tikva 4920235, Israel.
| | - Dror Kraus
- Pediatric Genetics Clinic, Schneider Children's Medical Center of Israel, Petach Tikva 4920235, Israel; Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel; Pediatric Epilepsy Unit, Neurological Institute, Schneider Children's Medical Center of Israel, Petach Tikva 4920235, Israel.
| | - Shay Tzur
- Mina and Everard Goodman Faculty of Life Science, Bar Ilan University, Ramat Gan 5290002, Israel; Laboratory of Molecular Medicine, Rambam Health Care Campus, Haifa 3109601, Israel; Genomic Research Department, Emedgene Technologies, Tel Aviv, Israel.
| | - Nurit Magal
- Raphael Recanati Genetics Institute, Rabin Medical Center- Beilinson Hospital, Petach Tikva 4941492, Israel; Felsenstein Medical Research Center, Rabin Medical Center, Petach Tikva 4941492, Israel.
| | - Yael Kilim
- Raphael Recanati Genetics Institute, Rabin Medical Center- Beilinson Hospital, Petach Tikva 4941492, Israel; Felsenstein Medical Research Center, Rabin Medical Center, Petach Tikva 4941492, Israel.
| | - Vered Shkalim Zemer
- Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel; Department of Hematology-Oncology, Schneider Children's Medical Center of Israel, Petach Tikva 4920235, Israel.
| | - Lina Basel-Salmon
- Pediatric Genetics Clinic, Schneider Children's Medical Center of Israel, Petach Tikva 4920235, Israel; Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel; Raphael Recanati Genetics Institute, Rabin Medical Center- Beilinson Hospital, Petach Tikva 4941492, Israel; Felsenstein Medical Research Center, Rabin Medical Center, Petach Tikva 4941492, Israel.
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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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Kojima K, Shirai K, Kobayashi M, Miyauchi A, Saitsu H, Matsumoto N, Osaka H, Yamagata T. A patient with early myoclonic encephalopathy (EME) with a de novo KCNQ2 mutation. Brain Dev 2018; 40:69-73. [PMID: 28687180 DOI: 10.1016/j.braindev.2017.06.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Revised: 05/29/2017] [Accepted: 06/14/2017] [Indexed: 12/20/2022]
Abstract
BACKGROUND The potassium voltage-gated channel subfamily Q member 2 (KCNQ2) gene has been reported to be associated with various types of epilepsy, including benign familial neonatal seizure (BFNS), early infantile epileptic encephalopathy (EIEE), and unclassified early onset encephalopathies. We herein report a patient with early myoclonic encephalopathy (EME) caused by a KCNQ2 mutation. CASE REPORT A male infant started to exhibit erratic myoclonus several days after birth and apnea attacks lasting for seconds with desaturation. One month after birth, his myoclonuses worsened in frequency. Electroencephalogram (EEG) showed a burst and suppression pattern, and myoclonuses occurred in the burst phase with diffuse polyspikes on EEG. At five months, inter-ictal EEG revealed hypsarrhythmia, but his attacks were still only myoclonuses. ACTH treatment was effective and the myoclonus frequency markedly decreased. At one year of age, whole-exome sequencing revealed a heterozygous mutation of the KCNQ2 gene (NM_172107.2): c.601C>T; p.(Arg201Cys), which was confirmed as de novo by Sanger sequencing. This mutation lies within the extracellular portion of the S4 voltage sensor. CONCLUSION Most patients with a KCNQ2 mutation present with seizures starting in the neonatal period with varying severity, ranging from BFNS to Ohtahara syndrome. Furthermore, KCNQ2 appears to be a causative gene for EME.
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Affiliation(s)
- Karin Kojima
- Department of Pediatrics, Jichi Medical University, Japan
| | - Kentaro Shirai
- Department of Pediatrics, Tsuchiura Kyodo Hospital, Japan
| | | | | | - Hirotomo Saitsu
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Japan; Department of Biochemistry, Hamamatsu Medical University, Japan
| | - Naomichi Matsumoto
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Japan
| | - Hitoshi Osaka
- Department of Pediatrics, Jichi Medical University, Japan
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Hernandez CC, Zhang Y, Hu N, Shen D, Shen W, Liu X, Kong W, Jiang Y, Macdonald RL. GABA A Receptor Coupling Junction and Pore GABRB3 Mutations are Linked to Early-Onset Epileptic Encephalopathy. Sci Rep 2017; 7:15903. [PMID: 29162865 PMCID: PMC5698489 DOI: 10.1038/s41598-017-16010-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Accepted: 10/11/2017] [Indexed: 12/17/2022] Open
Abstract
GABAA receptors are brain inhibitory chloride ion channels. Here we show functional analyses and structural simulations for three de novo missense mutations in the GABAA receptor β3 subunit gene (GABRB3) identified in patients with early-onset epileptic encephalopathy (EOEE) and profound developmental delay. We sought to obtain insights into the molecular mechanisms that might link defects in GABAA receptor biophysics and biogenesis to patients with EOEE. The mutant residues are part of conserved structural domains such as the Cys-loop (L170R) and M2-M3 loop (A305V) that form the GABA binding/channel gating coupling junction and the channel pore (T288N), which are functionally coupled during receptor activation. The mutant coupling junction residues caused rearrangements and formation of new hydrogen bonds in the open state, while the mutant pore residue reshaped the pore cavity. Whereas mutant coupling junction residues uncoupled during activation and caused gain of function, the mutant pore residue favoured low conductance receptors and differential sensitivity to diazepam and loss of function. These data reveal novel molecular mechanisms by which EOEE-linked mutations affect GABAA receptor function.
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Affiliation(s)
- Ciria C Hernandez
- Department of Neurology, Vanderbilt University, Nashville, TN., 37240-7915., USA. .,University of Michigan, Life Sciences Institute, 210 Washtenaw Ave., Room 6115, Ann Arbor, MI, 48109-2216, USA.
| | - Yujia Zhang
- Department of Pediatrics, Peking University First Hospital, Beijing, 100034, China
| | - Ningning Hu
- Department of Neurology, Vanderbilt University, Nashville, TN., 37240-7915., USA
| | - Dingding Shen
- The Graduate Program of Neuroscience, Vanderbilt University, Nashville, 37240-7915., TN, USA
| | - Wangzhen Shen
- Department of Neurology, Vanderbilt University, Nashville, TN., 37240-7915., USA
| | - Xiaoyan Liu
- Department of Pediatrics, Peking University First Hospital, Beijing, 100034, China
| | - Weijing Kong
- Department of Pediatrics, Peking University First Hospital, Beijing, 100034, China
| | - Yuwu Jiang
- Department of Pediatrics, Peking University First Hospital, Beijing, 100034, China.
| | - Robert L Macdonald
- Department of Neurology, Vanderbilt University, Nashville, TN., 37240-7915., USA.
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Hamdan FF, Myers CT, Cossette P, Lemay P, Spiegelman D, Laporte AD, Nassif C, Diallo O, Monlong J, Cadieux-Dion M, Dobrzeniecka S, Meloche C, Retterer K, Cho MT, Rosenfeld JA, Bi W, Massicotte C, Miguet M, Brunga L, Regan BM, Mo K, Tam C, Schneider A, Hollingsworth G, FitzPatrick DR, Donaldson A, Canham N, Blair E, Kerr B, Fry AE, Thomas RH, Shelagh J, Hurst JA, Brittain H, Blyth M, Lebel RR, Gerkes EH, Davis-Keppen L, Stein Q, Chung WK, Dorison SJ, Benke PJ, Fassi E, Corsten-Janssen N, Kamsteeg EJ, Mau-Them FT, Bruel AL, Verloes A, Õunap K, Wojcik MH, Albert DV, Venkateswaran S, Ware T, Jones D, Liu YC, Mohammad SS, Bizargity P, Bacino CA, Leuzzi V, Martinelli S, Dallapiccola B, Tartaglia M, Blumkin L, Wierenga KJ, Purcarin G, O’Byrne JJ, Stockler S, Lehman A, Keren B, Nougues MC, Mignot C, Auvin S, Nava C, Hiatt SM, Bebin M, Shao Y, Scaglia F, Lalani SR, Frye RE, Jarjour IT, Jacques S, Boucher RM, Riou E, Srour M, Carmant L, Lortie A, Major P, Diadori P, Dubeau F, D’Anjou G, Bourque G, Berkovic SF, Sadleir LG, Campeau PM, Kibar Z, Lafrenière RG, Girard SL, Mercimek-Mahmutoglu S, Boelman C, Rouleau GA, Scheffer IE, Mefford HC, Andrade DM, Rossignol E, Minassian BA, Michaud JL, Michaud JL. High Rate of Recurrent De Novo Mutations in Developmental and Epileptic Encephalopathies. Am J Hum Genet 2017; 101:664-685. [PMID: 29100083 DOI: 10.1016/j.ajhg.2017.09.008] [Citation(s) in RCA: 294] [Impact Index Per Article: 42.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Accepted: 09/11/2017] [Indexed: 12/30/2022] Open
Abstract
Developmental and epileptic encephalopathy (DEE) is a group of conditions characterized by the co-occurrence of epilepsy and intellectual disability (ID), typically with developmental plateauing or regression associated with frequent epileptiform activity. The cause of DEE remains unknown in the majority of cases. We performed whole-genome sequencing (WGS) in 197 individuals with unexplained DEE and pharmaco-resistant seizures and in their unaffected parents. We focused our attention on de novo mutations (DNMs) and identified candidate genes containing such variants. We sought to identify additional subjects with DNMs in these genes by performing targeted sequencing in another series of individuals with DEE and by mining various sequencing datasets. We also performed meta-analyses to document enrichment of DNMs in candidate genes by leveraging our WGS dataset with those of several DEE and ID series. By combining these strategies, we were able to provide a causal link between DEE and the following genes: NTRK2, GABRB2, CLTC, DHDDS, NUS1, RAB11A, GABBR2, and SNAP25. Overall, we established a molecular diagnosis in 63/197 (32%) individuals in our WGS series. The main cause of DEE in these individuals was de novo point mutations (53/63 solved cases), followed by inherited mutations (6/63 solved cases) and de novo CNVs (4/63 solved cases). De novo missense variants explained a larger proportion of individuals in our series than in other series that were primarily ascertained because of ID. Moreover, these DNMs were more frequently recurrent than those identified in ID series. These observations indicate that the genetic landscape of DEE might be different from that of ID without epilepsy.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - Jacques L Michaud
- Centre Hospitalier Universitaire Sainte-Justine Research Center, Montreal, QC H3T1C5, Canada; Department of Neurosciences, Université de Montréal, Montreal, QC H3T1J4, Canada; Department of Pediatrics, Université de Montréal, Montreal, QC H3T1C5, Canada.
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Symonds JD, Zuberi SM. Genetics update: Monogenetics, polygene disorders and the quest for modifying genes. Neuropharmacology 2017; 132:3-19. [PMID: 29037745 DOI: 10.1016/j.neuropharm.2017.10.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Revised: 10/09/2017] [Accepted: 10/11/2017] [Indexed: 12/19/2022]
Abstract
The genetic channelopathies are a broad collection of diseases. Many ion channel genes demonstrate wide phenotypic pleiotropy, but nonetheless concerted efforts have been made to characterise genotype-phenotype relationships. In this review we give an overview of the factors that influence genotype-phenotype relationships across this group of diseases as a whole, using specific individual channelopathies as examples. We suggest reasons for the limitations observed in these relationships. We discuss the role of ion channel variation in polygenic disease and highlight research that has contributed to unravelling the complex aetiological nature of these conditions. We focus specifically on the quest for modifying genes in inherited channelopathies, using the voltage-gated sodium channels as an example. Epilepsy related to genetic channelopathy is one area in which precision medicine is showing promise. We will discuss the successes and limitations of precision medicine in these conditions. This article is part of the Special Issue entitled 'Channelopathies.'
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Affiliation(s)
- Joseph D Symonds
- The Paediatric Neurosciences Research Group, Royal Hospital for Children, Queen Elizabeth University Hospitals, Glasgow, UK; School of Medicine, University of Glasgow, Glasgow, UK
| | - Sameer M Zuberi
- The Paediatric Neurosciences Research Group, Royal Hospital for Children, Queen Elizabeth University Hospitals, Glasgow, UK; School of Medicine, University of Glasgow, Glasgow, UK.
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Kang JQ. Defects at the crossroads of GABAergic signaling in generalized genetic epilepsies. Epilepsy Res 2017; 137:9-18. [PMID: 28865303 DOI: 10.1016/j.eplepsyres.2017.08.013] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Revised: 08/14/2017] [Accepted: 08/22/2017] [Indexed: 12/16/2022]
Abstract
Seizure disorders are very common and affect 3% of the general population. The recurrent unprovoked seizures that are also called epilepsies are highly diverse as to both underlying genetic basis and clinic presentations. Recent genetic advances and sequencing technologies indicate that many epilepsies previously thought to be without known causes, or idiopathic generalized epilepsies (IGEs), are virtually genetic epilepsy as they are caused by genetic variations. IGEs are estimated to account for ∼15-20% of all epilepsies. Initially IGEs were primarily considered channelopathies, because the first genetic defects identified in IGEs involved ion channel genes. However, new findings indicate that mutations in many non ion channel genes are also involved in addition to those in ion channel genes. Interestingly, mutations in many genes associated with epilepsy affect GABAergic signaling, a major biological pathway in epilepsy. Additionally, many antiepileptic drugs work via enhancing GABAergic signaling. Hence, the review will focus on the mutations that impair GABAergic signaling and selectively discuss the newly identified STXBP1, PRRT2, and DNM1 in addition to those long-established epilepsy ion channel genes that also impair GABAergic signaling like SCN1A and GABAA receptor subunit genes. GABAergic signaling includes the pre- and post- synaptic mechanisms. Some mutations, such as STXBP1, PRRT2, DNM1, and SCN1A, impair GABAergic signaling mainly via pre-synaptic mechanisms while those mutations in GABAA receptor subunit genes impair GABAergic signaling via post-synaptic mechanisms. Nevertheless, these findings suggest impaired GABAergic signaling is a converging pathway of defects for many ion channel or non ion channel mutations associated with genetic epilepsies.
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Affiliation(s)
- Jing-Qiong Kang
- Departments of Neurology, Vanderbilt University Medical Center, Nashville, TN, 37232-8552, USA; Affiliated Hospital of Nantong University, Jiangsu, 226001, China; Vanderbilt Brain Institute, Vanderbilt Kennedy Center of Human Development, Vanderbilt University, Nashville, TN, 37232-8522, USA.
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Ion Channel Genes and Epilepsy: Functional Alteration, Pathogenic Potential, and Mechanism of Epilepsy. Neurosci Bull 2017; 33:455-477. [PMID: 28488083 DOI: 10.1007/s12264-017-0134-1] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2016] [Accepted: 02/20/2017] [Indexed: 01/29/2023] Open
Abstract
Ion channels are crucial in the generation and modulation of excitability in the nervous system and have been implicated in human epilepsy. Forty-one epilepsy-associated ion channel genes and their mutations are systematically reviewed. In this paper, we analyzed the genotypes, functional alterations (funotypes), and phenotypes of these mutations. Eleven genes featured loss-of-function mutations and six had gain-of-function mutations. Nine genes displayed diversified funotypes, among which a distinct funotype-phenotype correlation was found in SCN1A. These data suggest that the funotype is an essential consideration in evaluating the pathogenicity of mutations and a distinct funotype or funotype-phenotype correlation helps to define the pathogenic potential of a gene.
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