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Gallagher D, Pérez-Palma E, Bruenger T, Ghanty I, Brilstra E, Ceulemans B, Chemaly N, de Lange I, Depienne C, Guerrini R, Mei D, Møller RS, Nabbout R, Regan BM, Schneider AL, Scheffer IE, Schoonjans AS, Symonds JD, Weckhuysen S, Zuberi SM, Lal D, Brunklaus A. Genotype-phenotype associations in 1018 individuals with SCN1A-related epilepsies. Epilepsia 2024; 65:1046-1059. [PMID: 38410936 DOI: 10.1111/epi.17882] [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: 09/17/2023] [Revised: 12/30/2023] [Accepted: 01/03/2024] [Indexed: 02/28/2024]
Abstract
OBJECTIVE SCN1A variants are associated with epilepsy syndromes ranging from mild genetic epilepsy with febrile seizures plus (GEFS+) to severe Dravet syndrome (DS). Many variants are de novo, making early phenotype prediction difficult, and genotype-phenotype associations remain poorly understood. METHODS We assessed data from a retrospective cohort of 1018 individuals with SCN1A-related epilepsies. We explored relationships between variant characteristics (position, in silico prediction scores: Combined Annotation Dependent Depletion (CADD), Rare Exome Variant Ensemble Learner (REVEL), SCN1A genetic score), seizure characteristics, and epilepsy phenotype. RESULTS DS had earlier seizure onset than other GEFS+ phenotypes (5.3 vs. 12.0 months, p < .001). In silico variant scores were higher in DS versus GEFS+ (p < .001). Patients with missense variants in functionally important regions (conserved N-terminus, S4-S6) exhibited earlier seizure onset (6.0 vs. 7.0 months, p = .003) and were more likely to have DS (280/340); those with missense variants in nonconserved regions had later onset (10.0 vs. 7.0 months, p = .036) and were more likely to have GEFS+ (15/29, χ2 = 19.16, p < .001). A minority of protein-truncating variants were associated with GEFS+ (10/393) and more likely to be located in the proximal first and last exon coding regions than elsewhere in the gene (9.7% vs. 1.0%, p < .001). Carriers of the same missense variant exhibited less variability in age at seizure onset compared with carriers of different missense variants for both DS (1.9 vs. 2.9 months, p = .001) and GEFS+ (8.0 vs. 11.0 months, p = .043). Status epilepticus as presenting seizure type is a highly specific (95.2%) but nonsensitive (32.7%) feature of DS. SIGNIFICANCE Understanding genotype-phenotype associations in SCN1A-related epilepsies is critical for early diagnosis and management. We demonstrate an earlier disease onset in patients with missense variants in important functional regions, the occurrence of GEFS+ truncating variants, and the value of in silico prediction scores. Status epilepticus as initial seizure type is a highly specific, but not sensitive, early feature of DS.
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Affiliation(s)
- Declan Gallagher
- School of Health and Wellbeing, University of Glasgow, Glasgow, UK
- Paediatric Neurosciences Research Group, Royal Hospital for Children, Glasgow, UK
| | - Eduardo Pérez-Palma
- Universidad del Desarrollo, Centro de Genética y Genómica, Facultad de Medicina Clínica Alemana, Santiago, Chile
- Cologne Center for Genomics, University of Cologne, Cologne, Germany
| | - Tobias Bruenger
- Cologne Center for Genomics, University of Cologne, Cologne, Germany
| | - Ismael Ghanty
- School of Health and Wellbeing, University of Glasgow, Glasgow, UK
- Paediatric Neurosciences Research Group, Royal Hospital for Children, Glasgow, UK
| | - Eva Brilstra
- Department of Genetics, University Medical Center, Utrecht, the Netherlands
| | - Berten Ceulemans
- Department of Child Neurology, University Hospital Antwerp, Antwerp, Belgium
| | - Nicole Chemaly
- Reference Center for Rare Epilepsies, Department of Pediatric Neurology, Hôpital Necker-Enfants Malades, Université de Paris, Paris, France
| | - Iris de Lange
- Department of Genetics, University Medical Center, Utrecht, the Netherlands
| | - Christel Depienne
- Institute of Human Genetics, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | - Renzo Guerrini
- Neuroscience Department, Children's Hospital A. Meyer Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) and University of Florence, Florence, Italy
| | - Davide Mei
- Neuroscience Department, Children's Hospital A. Meyer Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) and University of Florence, Florence, Italy
| | - Rikke S Møller
- Danish Epilepsy Center, Filadelfia, Dianalund, Denmark
- Department of Regional Health Research, Faculty of Health Sciences, University of Southern Denmark, Odense, Denmark
| | - Rima Nabbout
- Reference Center for Rare Epilepsies, Department of Pediatric Neurology, Hôpital Necker-Enfants Malades, Université de Paris, Paris, France
| | - Brigid M Regan
- Department of Medicine, Epilepsy Research Centre, University of Melbourne, Austin Health, Melbourne, Victoria, Australia
| | - Amy L Schneider
- Department of Medicine, Epilepsy Research Centre, University of Melbourne, Austin Health, Melbourne, Victoria, Australia
| | - Ingrid E Scheffer
- Department of Medicine, Epilepsy Research Centre, University of Melbourne, Austin Health, Melbourne, Victoria, Australia
- University of Melbourne, Royal Children's Hospital, Florey and Murdoch Children's Research Institutes, Melbourne, Victoria, Australia
| | - An-Sofie Schoonjans
- Department of Child Neurology, University Hospital Antwerp, Antwerp, Belgium
| | - Joseph D Symonds
- School of Health and Wellbeing, University of Glasgow, Glasgow, UK
- Paediatric Neurosciences Research Group, Royal Hospital for Children, Glasgow, UK
| | - Sarah Weckhuysen
- Applied & Translational Neurogenomics Group, VIB Center for Molecular Neurology, Antwerp, Belgium
- Neurology Department, University Hospital Antwerp, Antwerp, Belgium
- Translational Neurosciences, University of Antwerp, Antwerp, Belgium
| | - Sameer M Zuberi
- School of Health and Wellbeing, University of Glasgow, Glasgow, UK
- Paediatric Neurosciences Research Group, Royal Hospital for Children, Glasgow, UK
| | - Dennis Lal
- Cologne Center for Genomics, University of Cologne, Cologne, Germany
- Epilepsy Center, Neurological Institute, Cleveland Clinic, Cleveland, Ohio, USA
- Stanley Center for Psychiatric Genetics, Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
- Department of Neurology, McGovern Medical School, UTHealth Houston, Houston, Texas, USA
| | - Andreas Brunklaus
- School of Health and Wellbeing, University of Glasgow, Glasgow, UK
- Paediatric Neurosciences Research Group, Royal Hospital for Children, Glasgow, UK
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Witkowski G, Szulczyk B, Nurowska E, Jurek M, Pasierski M, Lipiec A, Charzewska A, Dawidziuk M, Milewski M, Owsiak S, Rola R, Sienkiewicz Jarosz H, Hoffman-Zacharska D. Functional Characteristics of the Nav1.1 p.Arg1596Cys Mutation Associated with Varying Severity of Epilepsy Phenotypes. Int J Mol Sci 2024; 25:1745. [PMID: 38339022 PMCID: PMC10855957 DOI: 10.3390/ijms25031745] [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: 12/29/2023] [Revised: 01/20/2024] [Accepted: 01/25/2024] [Indexed: 02/12/2024] Open
Abstract
Mutations of the SCN1A gene, which encodes the voltage-dependent Na+ channel's α subunit, are associated with diverse epileptic syndromes ranging in severity, even intra-family, from febrile seizures to epileptic encephalopathy. The underlying cause of this variability is unknown, suggesting the involvement of additional factors. The aim of our study was to describe the properties of mutated channels and investigate genetic causes for clinical syndromes' variability in the family of five SCN1A gene p.Arg1596Cys mutation carriers. The analysis of additional genetic factors influencing SCN1A-associated phenotypes was conducted through exome sequencing (WES). To assess the impact of mutations, we used patch clamp analysis of mutated channels expressed in HEK cells and in vivo neural excitability studies (NESs). In cells expressing the mutant channel, sodium currents were reduced. NESs indicated increased excitability of peripheral motor neurons in mutation carriers. WES showed the absence of non-SCA1 pathogenic variants that could be causative of disease in the family. Variants of uncertain significance in three genes, as potential modifiers of the most severe phenotype, were identified. The p.Arg1596Cys substitution inhibits channel function, affecting steady-state inactivation kinetics. Its clinical manifestations involve not only epileptic symptoms but also increased excitability of peripheral motor fibers. The role of Nav1.1 in excitatory neurons cannot be ruled out as a significant factor of the clinical phenotype.
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Affiliation(s)
- Grzegorz Witkowski
- First Department of Neurology, Institute of Psychiatry and Neurology, Sobieskiego 9, 02-957 Warsaw, Poland; (S.O.); (H.S.J.)
- Military Institute of Aviation Medicine, Krasinskiego 54/56, 01-755 Warsaw, Poland;
| | - Bartlomiej Szulczyk
- Chair and Department of Pharmacotherapy and Pharmaceutical Care, Faculty of Pharmacy, The Medical University of Warsaw, Banacha 1b, 02-097 Warsaw, Poland; (B.S.); (E.N.); (M.P.)
| | - Ewa Nurowska
- Chair and Department of Pharmacotherapy and Pharmaceutical Care, Faculty of Pharmacy, The Medical University of Warsaw, Banacha 1b, 02-097 Warsaw, Poland; (B.S.); (E.N.); (M.P.)
| | - Marta Jurek
- Department of Medical Genetics, Institute of Mother and Child, Kasprzaka 17a, 01-211 Warsaw, Poland; (M.J.); (A.C.); (M.M.); (D.H.-Z.)
| | - Michal Pasierski
- Chair and Department of Pharmacotherapy and Pharmaceutical Care, Faculty of Pharmacy, The Medical University of Warsaw, Banacha 1b, 02-097 Warsaw, Poland; (B.S.); (E.N.); (M.P.)
| | - Agata Lipiec
- Clinic of Pediatric Neurology, Institute of Mother and Child, Kasprzaka 17a, 01-211 Warsaw, Poland;
| | - Agnieszka Charzewska
- Department of Medical Genetics, Institute of Mother and Child, Kasprzaka 17a, 01-211 Warsaw, Poland; (M.J.); (A.C.); (M.M.); (D.H.-Z.)
| | - Mateusz Dawidziuk
- Department of Medical Genetics, Institute of Mother and Child, Kasprzaka 17a, 01-211 Warsaw, Poland; (M.J.); (A.C.); (M.M.); (D.H.-Z.)
| | - Michal Milewski
- Department of Medical Genetics, Institute of Mother and Child, Kasprzaka 17a, 01-211 Warsaw, Poland; (M.J.); (A.C.); (M.M.); (D.H.-Z.)
| | - Szymon Owsiak
- First Department of Neurology, Institute of Psychiatry and Neurology, Sobieskiego 9, 02-957 Warsaw, Poland; (S.O.); (H.S.J.)
| | - Rafal Rola
- Military Institute of Aviation Medicine, Krasinskiego 54/56, 01-755 Warsaw, Poland;
| | - Halina Sienkiewicz Jarosz
- First Department of Neurology, Institute of Psychiatry and Neurology, Sobieskiego 9, 02-957 Warsaw, Poland; (S.O.); (H.S.J.)
| | - Dorota Hoffman-Zacharska
- Department of Medical Genetics, Institute of Mother and Child, Kasprzaka 17a, 01-211 Warsaw, Poland; (M.J.); (A.C.); (M.M.); (D.H.-Z.)
- Institute of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, Miecznikowa 1, 02-096 Warsaw, Poland
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3
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Fang Z, Xie L, Li X, Gui J, Yang X, Han Z, Luo H, Huang D, Chen H, Cheng L, Jiang L. Severe epilepsy phenotype with SCN1A missense variants located outside the sodium channel core region: Relationship between functional results and clinical phenotype. Seizure 2022; 101:109-116. [PMID: 35944423 DOI: 10.1016/j.seizure.2022.07.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Revised: 07/17/2022] [Accepted: 07/29/2022] [Indexed: 11/28/2022] Open
Abstract
PURPOSE Most SCN1A missense variants located outside the sodium channel core region show a mild phenotype. However, there are exceptions, because of which it is challenging to determine the correlation between genotype and phenotype. In this study, we aimed to determine whether functional study could be used to determine disease severity in cases with such variants, and elucidate possible genotype-phenotype relationships. METHODS Forty-seven patients with SCN1A missense variants were recruited, and one with a Dravet syndrome phenotype with an SCN1A missense variant (c.3811T>C/ p.W1271R) located outside the core region was screened with electrophysiological tests. We also reviewed functional SCN1A studies on patients with inconsistent phenotypes and genotypes, and studied the relationship between electrophysiological measurements and clinical phenotype. RESULTS Patch clamp experiments showed that the W1271R variant caused significantly reduced sodium current, decreased channel voltage sensitivity, loss of channel availability, and prolonged recovery time from inactivation compared with wild type (WT), which ultimately caused a change in loss of function (LOF). Twelve cases of severe SCN1A-related epilepsy with missense variants located outside the channel core region were also included from the functional studies. Nine patients with missense SCN1A variants showed complete (3/9) or partial (6/9) physiological LOF. Two missense SCN1A variants caused physiological gain-and-loss of function (G-LOF), and one caused decreased excitability (DE). CONCLUSIONS Not all missense variants located outside the core region cause a mild phenotype. Although current functional studies in heterologous expression systems do not accurately reflect disease severity caused by SCN1A missense variants, they could be an effective model for generation of data to study the initial effects of SCN1A missense variants.
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Affiliation(s)
- Zhixu Fang
- Department of Neurology, Children's Hospital of Chongqing Medical University, National Clinical Research Center for Child Health and Disorders, Ministry of Education Key Laboratory of Child Development and Disorders, Chongqing Key Laboratory of Pediatrics, No. 136, Zhongshan Er Road, Yuzhong District, Chongqing 400014, China
| | - Lingling Xie
- Department of Neurology, Children's Hospital of Chongqing Medical University, National Clinical Research Center for Child Health and Disorders, Ministry of Education Key Laboratory of Child Development and Disorders, Chongqing Key Laboratory of Pediatrics, No. 136, Zhongshan Er Road, Yuzhong District, Chongqing 400014, China
| | - Xue Li
- Department of Neurology, Children's Hospital of Chongqing Medical University, National Clinical Research Center for Child Health and Disorders, Ministry of Education Key Laboratory of Child Development and Disorders, Chongqing Key Laboratory of Pediatrics, No. 136, Zhongshan Er Road, Yuzhong District, Chongqing 400014, China
| | - Jianxiong Gui
- Department of Neurology, Children's Hospital of Chongqing Medical University, National Clinical Research Center for Child Health and Disorders, Ministry of Education Key Laboratory of Child Development and Disorders, Chongqing Key Laboratory of Pediatrics, No. 136, Zhongshan Er Road, Yuzhong District, Chongqing 400014, China
| | - Xiaoyue Yang
- Department of Neurology, Children's Hospital of Chongqing Medical University, National Clinical Research Center for Child Health and Disorders, Ministry of Education Key Laboratory of Child Development and Disorders, Chongqing Key Laboratory of Pediatrics, No. 136, Zhongshan Er Road, Yuzhong District, Chongqing 400014, China
| | - Ziyao Han
- Department of Neurology, Children's Hospital of Chongqing Medical University, National Clinical Research Center for Child Health and Disorders, Ministry of Education Key Laboratory of Child Development and Disorders, Chongqing Key Laboratory of Pediatrics, No. 136, Zhongshan Er Road, Yuzhong District, Chongqing 400014, China
| | - Hanyu Luo
- Department of Neurology, Children's Hospital of Chongqing Medical University, National Clinical Research Center for Child Health and Disorders, Ministry of Education Key Laboratory of Child Development and Disorders, Chongqing Key Laboratory of Pediatrics, No. 136, Zhongshan Er Road, Yuzhong District, Chongqing 400014, China
| | - Dishu Huang
- Department of Neurology, Children's Hospital of Chongqing Medical University, National Clinical Research Center for Child Health and Disorders, Ministry of Education Key Laboratory of Child Development and Disorders, Chongqing Key Laboratory of Pediatrics, No. 136, Zhongshan Er Road, Yuzhong District, Chongqing 400014, China
| | - Hengsheng Chen
- Department of Neurology, Children's Hospital of Chongqing Medical University, National Clinical Research Center for Child Health and Disorders, Ministry of Education Key Laboratory of Child Development and Disorders, Chongqing Key Laboratory of Pediatrics, No. 136, Zhongshan Er Road, Yuzhong District, Chongqing 400014, China
| | - Li Cheng
- Department of Neurology, Children's Hospital of Chongqing Medical University, National Clinical Research Center for Child Health and Disorders, Ministry of Education Key Laboratory of Child Development and Disorders, Chongqing Key Laboratory of Pediatrics, No. 136, Zhongshan Er Road, Yuzhong District, Chongqing 400014, China
| | - Li Jiang
- Department of Neurology, Children's Hospital of Chongqing Medical University, National Clinical Research Center for Child Health and Disorders, Ministry of Education Key Laboratory of Child Development and Disorders, Chongqing Key Laboratory of Pediatrics, No. 136, Zhongshan Er Road, Yuzhong District, Chongqing 400014, China.
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4
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Hammer MF, Pan Y, Cumbay M, Pendziwiat M, Afawi Z, Goldberg-Stern H, Johnstone L, Helbig I, Cummins TR. Whole exome sequencing and co-expression analysis identify an SCN1A variant that modifies pathogenicity in a family with genetic epilepsy and febrile seizures plus. Epilepsia 2022; 63:1970-1980. [PMID: 35592948 PMCID: PMC10753192 DOI: 10.1111/epi.17296] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 05/06/2022] [Accepted: 05/06/2022] [Indexed: 01/19/2023]
Abstract
OBJECTIVE Family members carrying the same SCN1A variant often exhibit differences in the clinical severity of epilepsy. This variable expressivity suggests that other factors aside from the primary sodium channel variant influence the clinical manifestation. However, identifying such factors has proven challenging in humans. METHODS We perform whole exome sequencing (WES) in a large family in which an SCN1A variant (p.K1372E) is segregating that is associated with a broad spectrum of phenotypes ranging from lack of epilepsy, to febrile seizures and absence seizures, to Dravet syndrome. We assessed the hypothesis that the severity of the SCN1A-related phenotype was affected by alternate alleles at a modifier locus (or loci). RESULTS One of our top candidates identified by WES was a second variant in the SCN1A gene (p.L375S) that was shared exclusively by unaffected carriers of the K1372E allele. To test the hypothesized that L375S variant nullifies the loss-of-function effect of K1372E, we transiently expressed Nav1.1 carrying the two variants in HEK293T cells and compared their biophysical properties with the wild-type (WT) variant, and then co-expressed WT with K1372E or L375S with K1372E in equal quantity and tested the functional consequence. The data demonstrated that co-expression of the L375S and K1372E alleles reversed the loss-of-function property brought by the K1372E variant, whereas WT-K1372E co-expression remained partial loss-of-function. SIGNIFICANCE These results support the hypothesis that L375S counteracts the loss-of-function effect of K1372E such that individuals carrying both alleles in trans do not present epilepsy-related symptoms. We demonstrate that monogenic epilepsies with wide expressivity can be modified by additional variants in the disease gene, providing a novel framework for the gene-phenotype relationship in genetic epilepsies.
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Affiliation(s)
- Michael F. Hammer
- BIO5 Institute, University of Arizona, Tucson AZ USA
85716
- University of Arizona Genomics Core (UAGC), University of
Arizona, Tucson AZ USA 85716
| | - Yanling Pan
- Department of Biology, Indiana University-Purdue University
Indianapolis, Indianapolis IN 46202
| | - Medhane Cumbay
- Division of Biomedical Sciences, Marian University -
College of Osteopathic Medicine, Indianapolis, IN 46222
| | - Manuela Pendziwiat
- Department of Neuropediatrics, University Medical Center
Schleswig-Holstein Christian Albrechts University, Kiel, Germany
- Institute of Clinical Molecular Biology,
Christian-Albrechts-University of Kiel, Kiel, Germany
| | - Zaid Afawi
- Center for Neuroscience, Ben-Gurion University of the
Negev, Be’er Sheva 8410402, Israel
| | | | - Laurel Johnstone
- University of Arizona Genomics Core (UAGC), University of
Arizona, Tucson AZ USA 85716
| | - Ingo Helbig
- Institute of Clinical Molecular Biology,
Christian-Albrechts-University of Kiel, Kiel, Germany
- Division of Neurology, Children’s Hospital of
Philadelphia, Philadelphia, PA, 19104 USA
- The Epilepsy NeuroGenetics Initiative (ENGIN),
Children’s Hospital of Philadelphia, Philadelphia, USA
- Department of Biomedical and Health Informatics (DBHi),
Children’s Hospital of Philadelphia, Philadelphia, PA, 19104 USA
- Department of Neurology, University of Pennsylvania,
Perelman School of Medicine, Philadelphia, PA, 19104 USA
| | - Theodore R. Cummins
- Department of Biology, Indiana University-Purdue University
Indianapolis, Indianapolis IN 46202
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5
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Genetics and gene therapy in Dravet syndrome. Epilepsy Behav 2022; 131:108043. [PMID: 34053869 DOI: 10.1016/j.yebeh.2021.108043] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 05/02/2021] [Accepted: 05/02/2021] [Indexed: 12/17/2022]
Abstract
Dravet syndrome is a well-established electro-clinical condition first described in 1978. A main genetic cause was identified with the discovery of a loss-of-function SCN1A variant in 2001. Mechanisms underlying the phenotypic variations have subsequently been a main topic of research. Various genetic modifiers of clinical severities have been elucidated through many rigorous studies on genotype-phenotype correlations and the recent advances in next generation sequencing technology. Furthermore, a deeper understanding of the regulation of gene expression and remarkable progress on genome-editing technology using the CRISPR-Cas9 system provide significant opportunities to overcome hurdles of gene therapy, such as enhancing NaV1.1 expression. This article reviews the current understanding of genetic pathology and the status of research toward the development of gene therapy for Dravet syndrome. This article is part of the Special Issue "Severe Infantile Epilepsies".
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Alehabib E, Esmaeilizadeh Z, Ranji-Burachaloo S, Tafakhori A, Darvish H, Movafagh A. Clinical and molecular spectrum of P/Q type calcium channel Cav2.1 in epileptic patients. Orphanet J Rare Dis 2021; 16:461. [PMID: 34727962 PMCID: PMC8562004 DOI: 10.1186/s13023-021-02101-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Accepted: 10/24/2021] [Indexed: 11/24/2022] Open
Abstract
Background Epilepsy is a neurological disorder characterized by the potential to induce seizure and accompanied by cognitive, psychological, and social consequences. CACNA1A gene is a voltage-gated P/Q-type Cav2.1 channel that is broadly expressed in the central nervous system, and the pathogenic variants within this gene may be associated with the epileptic phenotype. In the present study, we collected clinical and molecular data related to epileptic patients with CACNA1A pathogenic variants and investigated possible meaningful relationship between age at onset, neurodevelopmental disorders, type of seizures, brain imaging abnormalities, genotype, and protein domains. Results In our retrospective literature studies, from among 890 articles reviewed, a total of 90 individuals were related to epilepsy phenotype. Our findings showed that about 90 percent of patients have shown the first symptoms in childhood and teenage years and different types of neurodevelopmental disorders, such as intellectual disability, developmental arrest, and behavioral disorders, have been common findings for these patients. Further, a wide range of abnormalities have been observed in their brain imaging, and generalized seizures have been the most type of seizures in these patients. However, our data showed no specific genotype–phenotype correlation in epileptic patients with CACNA1A pathogenic alterations. Conclusions Our study focused on epileptic phenotype in patients with CACNA1A pathogenic variants and showed a wide range of clinical and molecular heterogeneity with no specific genotype–phenotype correlation. It seems that incomplete penetrance, de-novo variants, and modifier genes are obstacles in predicting the clinical outcome. Supplementary Information The online version contains supplementary material available at 10.1186/s13023-021-02101-y.
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Affiliation(s)
- Elham Alehabib
- Student Research Committee, Department of Medical Genetics, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Zahra Esmaeilizadeh
- Department of Medical Genetics, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Sakineh Ranji-Burachaloo
- Iranian Center of Neurological Research, Neuroscience Institute, Tehran University of Medical Sciences, Tehran, Iran
| | - Abbas Tafakhori
- Iranian Center of Neurological Research, Neuroscience Institute, Tehran University of Medical Sciences, Tehran, Iran
| | - Hossein Darvish
- Neuroscience Research Center, Faculty of Medicine, Golestan University of Medical Sciences, Gorgan, Iran
| | - Abolfazl Movafagh
- Department of Medical Genetics, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
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Kubota T, Nabatame S, Sato R, Hama M, Nishiike U, Mochizuki H, Takahashi MP, Takeshima T. Hemiplegic migraine type 2 caused by a novel variant within the P-type ATPase motif in ATP1A2 concomitant with a CACNA1A variant. Brain Dev 2021; 43:952-957. [PMID: 34092402 DOI: 10.1016/j.braindev.2021.05.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 05/15/2021] [Accepted: 05/18/2021] [Indexed: 10/21/2022]
Abstract
BACKGROUND Familial hemiplegic migraine (FHM) is an inherited autosomal dominant disorder characterized by migraine with reversible hemiplegia. FHM1 is caused by variants in CACNA1A, encoding a P/Q type neuronal voltage-gated calcium channel α subunit, which is also associated with episodic ataxia type 2 (EA2). FHM2 is associated with ATP1A2, which codes for an Na+/K+-ATPase isoform 2 subunit. CASE PRESENTATION We identified an FHM2 family, the mother and her daughter, with a novel variant in ATP1A2, p.Gly377Asp, located in a well-conserved P-type ATPase motif. Additionally, the mother harbored deletion in the CACNA1A, associated with EA2, but her daughter did not. The mother presented migraine with typical aura without motor deficit, whereas her daughter had migraine accompanied by recurrent motor deficit and altered consciousness. The additional CACNA1A deletion in the mother might serve as a modifier. CONCLUSION Our report emphasizes the importance of genetic analysis to diagnose neurological ion channel/transporter diseases.
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Affiliation(s)
- Tomoya Kubota
- Department of Clinical Laboratory and Biomedical Sciences, Division of Health Sciences, Osaka University Graduate School of Medicine, 1-7, Yamadaoka, Suita, Osaka 5650871, Japan; Department of Neurology, Osaka University Graduate School of Medicine, 2-2, Yamadaoka, Suita, Osaka 5650871, Japan
| | - Shin Nabatame
- Department of Pediatrics, Osaka University Graduate School of Medicine, 2-2, Yamadaoka, Suita, Osaka 5650871, Japan
| | - Ruka Sato
- Department of Clinical Laboratory and Biomedical Sciences, Division of Health Sciences, Osaka University Graduate School of Medicine, 1-7, Yamadaoka, Suita, Osaka 5650871, Japan
| | - Manami Hama
- Department of Clinical Laboratory and Biomedical Sciences, Division of Health Sciences, Osaka University Graduate School of Medicine, 1-7, Yamadaoka, Suita, Osaka 5650871, Japan
| | - Ujiakira Nishiike
- Department of Neurology, Osaka University Graduate School of Medicine, 2-2, Yamadaoka, Suita, Osaka 5650871, Japan
| | - Hideki Mochizuki
- Department of Neurology, Osaka University Graduate School of Medicine, 2-2, Yamadaoka, Suita, Osaka 5650871, Japan
| | - Masanori P Takahashi
- Department of Clinical Laboratory and Biomedical Sciences, Division of Health Sciences, Osaka University Graduate School of Medicine, 1-7, Yamadaoka, Suita, Osaka 5650871, Japan; Department of Neurology, Osaka University Graduate School of Medicine, 2-2, Yamadaoka, Suita, Osaka 5650871, Japan.
| | - Takao Takeshima
- Department of Neurology, Tominaga Hospital, 1-4-48, Minato-cho, Naniwa-ku, Osaka, Osaka 5560017, Japan.
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Stringer RN, Jurkovicova-Tarabova B, Souza IA, Ibrahim J, Vacik T, Fathalla WM, Hertecant J, Zamponi GW, Lacinova L, Weiss N. De novo SCN8A and inherited rare CACNA1H variants associated with severe developmental and epileptic encephalopathy. Mol Brain 2021; 14:126. [PMID: 34399820 PMCID: PMC8365958 DOI: 10.1186/s13041-021-00838-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Accepted: 08/01/2021] [Indexed: 02/08/2023] Open
Abstract
Developmental and epileptic encephalopathies (DEEs) are a group of severe epilepsies that are characterized by seizures and developmental delay. DEEs are primarily attributed to genetic causes and an increasing number of cases have been correlated with variants in ion channel genes. In this study, we report a child with an early severe DEE. Whole exome sequencing showed a de novo heterozygous variant (c.4873–4881 duplication) in the SCN8A gene and an inherited heterozygous variant (c.952G > A) in the CACNA1H gene encoding for Nav1.6 voltage-gated sodium and Cav3.2 voltage-gated calcium channels, respectively. In vitro functional analysis of human Nav1.6 and Cav3.2 channel variants revealed mild but significant alterations of their gating properties that were in general consistent with a gain- and loss-of-channel function, respectively. Although additional studies will be required to confirm the actual pathogenic involvement of SCN8A and CACNA1H, these findings add to the notion that rare ion channel variants may contribute to the etiology of DEEs.
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Affiliation(s)
- Robin N Stringer
- Department of Pathophysiology, Third Faculty of Medicine, Charles University, Prague, Czech Republic.,Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Prague, Czech Republic
| | - Bohumila Jurkovicova-Tarabova
- Center of Biosciences, Institute of Molecular Physiology and Genetics, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Ivana A Souza
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Canada
| | - Judy Ibrahim
- Department of Pediatrics, Tawam Hospital, Al-Ain, United Arab Emirates
| | - Tomas Vacik
- Institute of Biology and Medical Genetics, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | | | - Jozef Hertecant
- Department of Pediatrics, Tawam Hospital, Al-Ain, United Arab Emirates.,Department of Pediatrics, College of Medicine and Health Sciences, United Arab Emirates University, Al-Ain, United Arab Emirates
| | - Gerald W Zamponi
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Canada
| | - Lubica Lacinova
- Center of Biosciences, Institute of Molecular Physiology and Genetics, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Norbert Weiss
- Department of Pathophysiology, Third Faculty of Medicine, Charles University, Prague, Czech Republic. .,Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Prague, Czech Republic. .,Center of Biosciences, Institute of Molecular Physiology and Genetics, Slovak Academy of Sciences, Bratislava, Slovakia. .,Institute of Biology and Medical Genetics, First Faculty of Medicine, Charles University, Prague, Czech Republic.
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9
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Abstract
The presence of unprovoked, recurrent seizures, particularly when drug resistant and associated with cognitive and behavioral deficits, warrants investigation for an underlying genetic cause. This article provides an overview of the major classes of genes associated with epilepsy phenotypes divided into functional categories along with the recommended work-up and therapeutic considerations. Gene discovery in epilepsy supports counseling and anticipatory guidance but also opens the door for precision medicine guiding therapy with a focus on those with disease-modifying effects.
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Affiliation(s)
- Luis A Martinez
- Department of Pediatrics, Section of Pediatric Neurology and Developmental Neuroscience, Baylor College of Medicine, Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, 1250 Moursund Drive, Houston, TX 77030, USA
| | - Yi-Chen Lai
- Department of Pediatrics, Section of Pediatric Critical Care Medicine, Baylor College of Medicine, Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, 1250 Moursund Drive, Houston, TX 77030, USA
| | - J Lloyd Holder
- Department of Pediatrics, Section of Pediatric Neurology and Developmental Neuroscience, Baylor College of Medicine, Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, 1250 Moursund Drive, Houston, TX 77030, USA
| | - Anne E Anderson
- Department of Pediatrics, Section of Pediatric Neurology and Developmental Neuroscience, Baylor College of Medicine, Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, 1250 Moursund Drive, Houston, TX 77030, USA.
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10
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Pulvirenti G, Caccamo M, Lo Bianco M, Mazzurco M, Praticò ER, Giallongo A, Gangi G, Zanghì A, Falsaperla R. Calcium Channels Genes and Their Epilepsy Phenotypes. JOURNAL OF PEDIATRIC NEUROLOGY 2021. [DOI: 10.1055/s-0041-1728684] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
AbstractCalcium (Ca2+) channel gene mutations play an important role in the pathogenesis of neurological episodic disorders like epilepsy. CACNA1A and CACNA1H genes are involved in the synthesis of calcium channels. Mutations in the α1A subunit of the P/Q type voltage-gated calcium channel gene (CACNA1A) located in 19p13.13, which encodes for the transmembrane pore-forming subunit of CAV2.1 voltage-dependent calcium channel, have been correlated to a large clinical spectrum of epilepsy such as idiopathic genetic epilepsy, early infantile epilepsy, and febrile seizures. Moreover, CACNA1A mutations have been demonstrated to be involved in spinocerebellar ataxia type 6, familiar hemiplegic migraine, episodic ataxia type 2, early-onset encephalopathy, and hemiconvulsion–hemiplegia epilepsy syndrome. This wide phenotype heterogeneity associated with CACNA1A mutations is correlated to different clinical and electrophysiological manifestations. CACNA1H gene, located in 16p13.3, encodes the α1H subunit of T-type calcium channel, expressing the transmembrane pore-forming subunit Cav3.2. Despite data still remain controversial, it has been identified as an important gene whose mutations seem strictly related to the pathogenesis of childhood absence epilepsy and other generalized epilepsies. The studied variants are mainly gain-of-function, hence responsible for an increase in neuronal susceptibility to seizures. CACNA1H mutations have also been associated with autism spectrum disorder and other behavior disorders. More recently, also amyotrophic lateral sclerosis has been related to CACNA1H alterations. The aim of this review, other than describe the CACNA1A and CACNA1H gene functions, is to identify mutations reported in literature and to analyze their possible correlations with specific epileptic disorders, purposing to guide an appropriate medical treatment recommendation.
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Affiliation(s)
- Giulio Pulvirenti
- Pediatrics Postgraduate Residency Program, Section of Pediatrics and Child Neuropsychiatry, Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy
| | - Martina Caccamo
- Pediatrics Postgraduate Residency Program, Section of Pediatrics and Child Neuropsychiatry, Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy
| | - Manuela Lo Bianco
- Pediatrics Postgraduate Residency Program, Section of Pediatrics and Child Neuropsychiatry, Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy
| | | | | | - Alessandro Giallongo
- Pediatrics Postgraduate Residency Program, Section of Pediatrics and Child Neuropsychiatry, Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy
| | - Gloria Gangi
- Pediatrics Postgraduate Residency Program, Section of Pediatrics and Child Neuropsychiatry, Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy
| | - Antonio Zanghì
- Department of Medical and Surgical Sciences and Advanced Technology “G.F. Ingrassia,” University of Catania, Catania, Italy
| | - Raffaele Falsaperla
- Unit of Pediatrics and Pediatric Emergency, University Hospital “Policlinico Rodolico-San Marco,” Catania, Italy
- Unit of Neonatal Intensive Care and Neonatology, University Hospital “Policlinico Rodolico-San Marco,” Catania, Italy
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11
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Ohmori I, Kobayashi K, Ouchida M. Scn1a and Cacna1a mutations mutually alter their original phenotypes in rats. Neurochem Int 2020; 141:104859. [PMID: 33045260 DOI: 10.1016/j.neuint.2020.104859] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 08/31/2020] [Accepted: 09/26/2020] [Indexed: 12/20/2022]
Abstract
This study aimed to examine the effects of Cacna1a mutation on the phenotype of Scn1a-associated epilepsy in rats. We used rats with an N1417H missense mutation in the Scn1a gene and others with an M251K mutation in the Cacna1a gene. Scn1a/Cacna1a double mutant rats were generated by mating both Scn1a and Cacna1a mutants. We investigated general health and the epileptic phenotype in all these genotypes. The onset threshold of hyperthermia-induced seizures was examined at 5 weeks and spontaneous seizures were monitored using video-EEG recordings from 6 to 12 weeks of age. Scn1a/Cacna1a double mutants showed significantly reduced threshold for hyperthermia-sensitive seizures onset compared with the Scn1a mutants and had absence seizures having 6-7 c/s spike-wave bursts with changes in the spike-wave pattern, whereas Cacna1a mutants had regular 6-7 c/s spike-wave bursts. In Scn1a/Cacna1a double mutants, 6-7 c/s spike-wave bursts were accompanied with eyelid myoclonia and continuously shifting generalized clonic seizures, which were not observed in either Scn1a or Cacna1a mutants. Although a curvature of the spine was observed in rats of all these genotypes, the degree of curvature was more pronounced in Scn1a/Cacna1a double mutants, followed by Cacna1a and Scn1a mutants. Our results indicate that Cacna1a and Scn1a mutations mutually alter their original phenotypes in rats. The phenotype of absence seizures with eyelid myoclonia, generalized clonic seizures, and of spine curvature in the Scn1a/Cacna1a double mutants were similar to that observed in patients with Dravet syndrome.
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Affiliation(s)
- Iori Ohmori
- Graduate School of Education, Okayama University, Tsushima 3-chome 1-1, Kita-ku, Okayama, 700-8530, Japan; Department of Child Neurology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Shikatacho 2-chome 5-1, Kita-ku, Okayama, 700-8558, Japan; Department of Physiology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Shikatacho 2-chome 5-1, Kita-ku, Okayama, 700-8558, Japan.
| | - Kiyoka Kobayashi
- Department of Physiology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Shikatacho 2-chome 5-1, Kita-ku, Okayama, 700-8558, Japan
| | - Mamoru Ouchida
- Department of Molecular Oncology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Shikatacho 2-chome 5-1, Kita-ku, Okayama, 700-8558, Japan
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12
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Kluckova D, Kolnikova M, Lacinova L, Jurkovicova-Tarabova B, Foltan T, Demko V, Kadasi L, Ficek A, Soltysova A. A Study among the Genotype, Functional Alternations, and Phenotype of 9 SCN1A Mutations in Epilepsy Patients. Sci Rep 2020; 10:10288. [PMID: 32581296 PMCID: PMC7314844 DOI: 10.1038/s41598-020-67215-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Accepted: 05/26/2020] [Indexed: 12/14/2022] Open
Abstract
Mutations in the voltage-gated sodium channel Nav1.1 (SCN1A) are linked to various epileptic phenotypes with different severities, however, the consequences of newly identified SCN1A variants on patient phenotype is uncertain so far. The functional impact of nine SCN1A variants, including five novel variants identified in this study, was studied using whole-cell patch-clamp recordings measurement of mutant Nav1.1 channels expressed in HEK293T mammalian cells. E78X, W384X, E1587K, and R1596C channels failed to produce measurable sodium currents, indicating complete loss of channel function. E788K and M909K variants resulted in partial loss of function by exhibiting reduced current density, depolarizing shifts of the activation and hyperpolarizing shifts of the inactivation curves, and slower recovery from inactivation. Hyperpolarizing shifts of the activation and inactivation curves were observed in D249E channels along with slower recovery from inactivation. Slower recovery from inactivation was observed in E78D and T1934I with reduced current density in T1934I channels. Various functional effects were observed with the lack of sodium current being mainly associated with severe phenotypes and milder symptoms with less damaging channel alteration. In vitro functional analysis is thus fundamental for elucidation of the molecular mechanisms of epilepsy, to guide patients' treatment, and finally indicate misdiagnosis of SCN1A related epilepsies.
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Affiliation(s)
- Daniela Kluckova
- Department of Molecular Biology, Faculty of Natural Sciences, Comenius University, Ilkovicova 6, Bratislava, 842 15, Slovakia
| | - Miriam Kolnikova
- Department of Pediatric Neurology, Comenius University Medical School and National Institute of Children's Diseases, Limbova 1, Bratislava, 833 40, Slovakia
| | - Lubica Lacinova
- Center of Biosciences, Institute of Molecular Physiology and Genetics, Slovak Academy of Sciences, Dubravská cesta 9, Bratislava, 840 05, Slovakia
| | - Bohumila Jurkovicova-Tarabova
- Center of Biosciences, Institute of Molecular Physiology and Genetics, Slovak Academy of Sciences, Dubravská cesta 9, Bratislava, 840 05, Slovakia
| | - Tomas Foltan
- Department of Pediatric Neurology, Comenius University Medical School and National Institute of Children's Diseases, Limbova 1, Bratislava, 833 40, Slovakia
| | - Viktor Demko
- Department of Plant Physiology, Faculty of Natural Sciences, Comenius University, Ilkovicova 6, Bratislava, 842 15, Slovakia
| | - Ludevit Kadasi
- Department of Molecular Biology, Faculty of Natural Sciences, Comenius University, Ilkovicova 6, Bratislava, 842 15, Slovakia.,Institute for Clinical and Translational Research, Biomedical Research Center, Slovak Academy of Sciences, Dubravska cesta 9, 845 05, Bratislava, Slovakia
| | - Andrej Ficek
- Department of Molecular Biology, Faculty of Natural Sciences, Comenius University, Ilkovicova 6, Bratislava, 842 15, Slovakia
| | - Andrea Soltysova
- Department of Molecular Biology, Faculty of Natural Sciences, Comenius University, Ilkovicova 6, Bratislava, 842 15, Slovakia. .,Institute for Clinical and Translational Research, Biomedical Research Center, Slovak Academy of Sciences, Dubravska cesta 9, 845 05, Bratislava, Slovakia.
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13
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D'Adamo MC, Liantonio A, Conte E, Pessia M, Imbrici P. Ion Channels Involvement in Neurodevelopmental Disorders. Neuroscience 2020; 440:337-359. [PMID: 32473276 DOI: 10.1016/j.neuroscience.2020.05.032] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 05/16/2020] [Accepted: 05/19/2020] [Indexed: 12/14/2022]
Abstract
Inherited and sporadic mutations in genes encoding for brain ion channels, affecting membrane expression or biophysical properties, have been associated with neurodevelopmental disorders characterized by epilepsy, cognitive and behavioral deficits with significant phenotypic and genetic heterogeneity. Over the years, the screening of a growing number of patients and the functional characterization of newly identified mutations in ion channels genes allowed to recognize new phenotypes and to widen the clinical spectrum of known diseases. Furthermore, advancements in understanding disease pathogenesis at atomic level or using patient-derived iPSCs and animal models have been pivotal to orient therapeutic intervention and to put the basis for the development of novel pharmacological options for drug-resistant disorders. In this review we will discuss major improvements and critical issues concerning neurodevelopmental disorders caused by dysfunctions in brain sodium, potassium, calcium, chloride and ligand-gated ion channels.
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Affiliation(s)
- Maria Cristina D'Adamo
- Department of Physiology and Biochemistry, Faculty of Medicine and Surgery, University of Malta, Malta
| | | | - Elena Conte
- Department of Pharmacy-Drug Sciences, University of Bari "Aldo Moro", Italy
| | - Mauro Pessia
- Department of Physiology and Biochemistry, Faculty of Medicine and Surgery, University of Malta, Malta; Department of Physiology, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
| | - Paola Imbrici
- Department of Pharmacy-Drug Sciences, University of Bari "Aldo Moro", Italy.
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14
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Bueichekú E, Aznárez-Sanado M, Diez I, d'Oleire Uquillas F, Ortiz-Terán L, Qureshi AY, Suñol M, Basaia S, Ortiz-Terán E, Pastor MA, Sepulcre J. Central neurogenetic signatures of the visuomotor integration system. Proc Natl Acad Sci U S A 2020; 117:6836-6843. [PMID: 32144139 PMCID: PMC7104395 DOI: 10.1073/pnas.1912429117] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Visuomotor impairments characterize numerous neurological disorders and neurogenetic syndromes, such as autism spectrum disorder (ASD) and Dravet, Fragile X, Prader-Willi, Turner, and Williams syndromes. Despite recent advances in systems neuroscience, the biological basis underlying visuomotor functional impairments associated with these clinical conditions is poorly understood. In this study, we used neuroimaging connectomic approaches to map the visuomotor integration (VMI) system in the human brain and investigated the topology approximation of the VMI network to the Allen Human Brain Atlas, a whole-brain transcriptome-wide atlas of cortical genetic expression. We found the genetic expression of four genes-TBR1, SCN1A, MAGEL2, and CACNB4-to be prominently associated with visuomotor integrators in the human cortex. TBR1 gene transcripts, an ASD gene whose expression is related to neural development of the cortex and the hippocampus, showed a central spatial allocation within the VMI system. Our findings delineate gene expression traits underlying the VMI system in the human cortex, where specific genes, such as TBR1, are likely to play a central role in its neuronal organization, as well as on specific phenotypes of neurogenetic syndromes.
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Affiliation(s)
- Elisenda Bueichekú
- Gordon Center for Medical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02115
- Department of Basic Psychology, Clinical Psychology and Psychobiology, Jaume I University, 12071 Castelló de la Plana, Spain
| | - Maite Aznárez-Sanado
- Neuroimaging Laboratory, School of Medicine, University of Navarra, 31008 Pamplona, Spain
- School of Education and Psychology, University of Navarra, 31008 Pamplona, Spain
| | - Ibai Diez
- Gordon Center for Medical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02115
- Neurotechnology Laboratory, Health Department, Tecnalia, E-48160 Derio, Spain
| | - Federico d'Oleire Uquillas
- Princeton Neuroscience Institute, Princeton University, Princeton, NJ, 08540
- Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129
| | - Laura Ortiz-Terán
- Gordon Center for Medical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02115
- Department of Radiology, Brigham and Women's Hospital, Boston MA 02115
| | - Abid Y Qureshi
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129
- Department of Neurology, University of Kansas Medical Center, Kansas City, MO 66160
| | - Maria Suñol
- Gordon Center for Medical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02115
- Psychiatry Department, Bellvitge University Hospital, Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), 08907 L'Hospitalet de Llobregat, Barcelona, Spain
- Center for Biomedical Research in Mental Health Network, Carlos III Health Institute, 08907 L'Hospitalet de Llobregat, Barcelona, Spain
- Department of Clinical Sciences, School of Medicine, University of Barcelona, 08036 Barcelona, Spain
| | - Silvia Basaia
- Gordon Center for Medical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02115
- Neuroimaging Research Unit, San Raffaele Scientific Institute, Vita-Salute San Raffaele University, 20132 Milan, Italy
| | - Elena Ortiz-Terán
- Gordon Center for Medical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02115
| | - Maria A Pastor
- Neuroimaging Laboratory, School of Medicine, University of Navarra, 31008 Pamplona, Spain
| | - Jorge Sepulcre
- Gordon Center for Medical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02115;
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129
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15
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de Lange IM, Mulder F, van 't Slot R, Sonsma ACM, van Kempen MJA, Nijman IJ, Ernst RF, Knoers NVAM, Brilstra EH, Koeleman BPC. Modifier genes in SCN1A-related epilepsy syndromes. Mol Genet Genomic Med 2020; 8:e1103. [PMID: 32032478 PMCID: PMC7196470 DOI: 10.1002/mgg3.1103] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Revised: 11/25/2019] [Accepted: 11/26/2019] [Indexed: 12/24/2022] Open
Abstract
Background SCN1A is one of the most important epilepsy‐related genes, with pathogenic variants leading to a range of phenotypes with varying disease severity. Different modifying factors have been hypothesized to influence SCN1A‐related phenotypes. We investigate the presence of rare and more common variants in epilepsy‐related genes as potential modifiers of SCN1A‐related disease severity. Methods 87 patients with SCN1A‐related epilepsy were investigated. Whole‐exome sequencing was performed by the Beijing Genomics Institute (BGI). Functional variants in 422 genes associated with epilepsy and/or neuronal excitability were investigated. Differences in proportions of variants between the epilepsy genes and four control gene sets were calculated, and compared to the proportions of variants in the same genes in the ExAC database. Results Statistically significant excesses of variants in epilepsy genes were observed in the complete cohort and in the combined group of mildly and severely affected patients, particularly for variants with minor allele frequencies of <0.05. Patients with extreme phenotypes showed much greater excesses of epilepsy gene variants than patients with intermediate phenotypes. Conclusion Our results indicate that relatively common variants in epilepsy genes, which would not necessarily be classified as pathogenic, may play a large role in modulating SCN1A phenotypes. They may modify the phenotypes of both severely and mildly affected patients. Our results may be a first step toward meaningful testing of modifier gene variants in regular diagnostics for individual patients, to provide a better estimation of disease severity for newly diagnosed patients.
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Affiliation(s)
- Iris M de Lange
- Department of Genetics, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Flip Mulder
- Department of Genetics, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Ruben van 't Slot
- Department of Genetics, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Anja C M Sonsma
- Department of Genetics, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Marjan J A van Kempen
- Department of Genetics, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Isaac J Nijman
- Department of Genetics, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Robert F Ernst
- Department of Genetics, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Nine V A M Knoers
- Department of Genetics, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht, The Netherlands.,Department of Genetics, University Medical Center Groningen, Groningen, The Netherlands
| | - Eva H Brilstra
- Department of Genetics, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Bobby P C Koeleman
- Department of Genetics, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht, The Netherlands
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16
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Xie Y, Ng NN, Safrina OS, Ramos CM, Ess KC, Schwartz PH, Smith MA, O'Dowd DK. Comparisons of dual isogenic human iPSC pairs identify functional alterations directly caused by an epilepsy associated SCN1A mutation. Neurobiol Dis 2019; 134:104627. [PMID: 31786370 DOI: 10.1016/j.nbd.2019.104627] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 09/05/2019] [Accepted: 09/26/2019] [Indexed: 02/06/2023] Open
Abstract
Over 1250 mutations in SCN1A, the Nav1.1 voltage-gated sodium channel gene, are associated with seizure disorders including GEFS+. To evaluate how a specific mutation, independent of genetic background, causes seizure activity we generated two pairs of isogenic human iPSC lines by CRISPR/Cas9 gene editing. One pair is a control line from an unaffected sibling, and the mutated control carrying the GEFS+ K1270T SCN1A mutation. The second pair is a GEFS+ patient line with the K1270T mutation, and the corrected patient line. By comparing the electrophysiological properties in inhibitory and excitatory iPSC-derived neurons from these pairs, we found the K1270T mutation causes cell type-specific alterations in sodium current density and evoked firing, resulting in hyperactive neural networks. We also identified differences associated with genetic background and interaction between the mutation and genetic background. Comparisons within and between dual pairs of isogenic iPSC-derived neuronal cultures provide a novel platform for evaluating cellular mechanisms underlying a disease phenotype and for developing patient-specific anti-seizure therapies.
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Affiliation(s)
- Yunyao Xie
- Department of Developmental and Cell Biology, University of California, Irvine, CA, United States of America
| | - Nathan N Ng
- Department of Developmental and Cell Biology, University of California, Irvine, CA, United States of America
| | - Olga S Safrina
- Department of Developmental and Cell Biology, University of California, Irvine, CA, United States of America
| | - Carmen M Ramos
- Department of Developmental and Cell Biology, University of California, Irvine, CA, United States of America
| | - Kevin C Ess
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN, United States of America
| | - Philip H Schwartz
- Children's Hospital of Orange County Research Institute, Orange, CA, United States of America
| | - Martin A Smith
- Department of Anatomy and Neurobiology, University of California, Irvine, CA, United States of America
| | - Diane K O'Dowd
- Department of Developmental and Cell Biology, University of California, Irvine, CA, United States of America.
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17
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de Lange IM, Koudijs MJ, van ‘t Slot R, Sonsma ACM, Mulder F, Carbo EC, van Kempen MJA, Nijman IJ, Ernst RF, Savelberg SMC, Knoers NVAM, Brilstra EH, Koeleman BPC. Assessment of parental mosaicism in SCN1A-related epilepsy by single-molecule molecular inversion probes and next-generation sequencing. J Med Genet 2018; 56:75-80. [DOI: 10.1136/jmedgenet-2018-105672] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Revised: 09/24/2018] [Accepted: 09/30/2018] [Indexed: 01/08/2023]
Abstract
BackgroundDravet syndrome is a severe genetic encephalopathy, caused by pathogenic variants in SCN1A. Low-grade parental mosaicism occurs in a substantial proportion of families (7%–13%) and has important implications for recurrence risks. However, parental mosaicism can remain undetected by methods regularly used in diagnostics. In this study, we use single-molecule molecular inversion probes (smMIP), a technique with high sensitivity for detecting low-grade mosaic variants and high cost-effectiveness, to investigate the incidence of parental mosaicism of SCN1A variants in a cohort of 90 families and assess the feasibility of this technique.MethodsDeep sequencing of SCN1A was performed using smMIPs. False positive rates for each of the proband’s pathogenic variants were determined in 145 unrelated samples. If parents showed corresponding variant alleles at a significantly higher rate than the established noise ratio, mosaicism was confirmed by droplet digital PCR (ddPCR).ResultsSequence coverage of at least 100× at the location of the corresponding pathogenic variant was reached for 80 parent couples. The variant ratio was significantly higher than the established noise ratio in eight parent couples, of which four (5%) were regarded as true mosaics, based on ddPCR results. The false positive rate of smMIP analysis without ddPCR was therefore 50%. Three of these variants had previously been considered de novo in the proband by Sanger sequencing.ConclusionsmMIP technology combined withnext generation sequencing (NGS) performs better than Sanger sequencing in the detection of parental mosaicism. Because parental mosaicism has important implications for genetic counselling and recurrence risks, we stress the importance of implementing high-sensitivity NGS-based assays in standard diagnostics.
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18
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de Lange IM, Gunning B, Sonsma ACM, van Gemert L, van Kempen M, Verbeek NE, Nicolai J, Knoers NVAM, Koeleman BPC, Brilstra EH. Influence of contraindicated medication use on cognitive outcome in Dravet syndrome and age at first afebrile seizure as a clinical predictor in SCN1A
-related seizure phenotypes. Epilepsia 2018; 59:1154-1165. [DOI: 10.1111/epi.14191] [Citation(s) in RCA: 85] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/06/2018] [Indexed: 11/29/2022]
Affiliation(s)
- Iris M. de Lange
- Department of Medical Genetics; University Medical Center Utrecht; Utrecht University; Utrecht The Netherlands
| | - Boudewijn Gunning
- The Epilepsy Institutes of The Netherlands Foundation (SEIN); Zwolle The Netherlands
| | - Anja C. M. Sonsma
- Department of Medical Genetics; University Medical Center Utrecht; Utrecht University; Utrecht The Netherlands
| | | | - Marjan van Kempen
- Department of Medical Genetics; University Medical Center Utrecht; Utrecht University; Utrecht The Netherlands
| | - Nienke E. Verbeek
- Department of Medical Genetics; University Medical Center Utrecht; Utrecht University; Utrecht The Netherlands
| | - Joost Nicolai
- Academical Center of Epileptology; Maastricht and Heeze The Netherlands
| | - Nine V. A. M. Knoers
- Department of Medical Genetics; University Medical Center Utrecht; Utrecht University; Utrecht The Netherlands
| | - Bobby P. C. Koeleman
- Department of Medical Genetics; University Medical Center Utrecht; Utrecht University; Utrecht The Netherlands
| | - Eva H. Brilstra
- Department of Medical Genetics; University Medical Center Utrecht; Utrecht University; Utrecht The Netherlands
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Liao J, Tian X, Wang H, Xiao Z. Epilepsy and migraine-Are they comorbidity? Genes Dis 2018; 5:112-118. [PMID: 30258939 PMCID: PMC6146266 DOI: 10.1016/j.gendis.2018.04.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Accepted: 04/17/2018] [Indexed: 12/13/2022] Open
Abstract
Epilepsy and migraine often co-occur. From the clinical symptoms, they often have some signs of symptoms before onset; from the pathogenesis of epilepsy and migraine, both of them have a high degree of neuronal excitement and ion channel abnormalities; in terms of treatment, many antiepileptic drugs are work in migraine. All of this indicates that they interact with each other. But it is undeniable that there are interactions and relationships between them, and there are also some differences such as the different clinical episodes, the different ways of neuronal haperexcitability and the different drug treatment programs. And are they comorbidity? If we can better understand the correlation between seizures and migraines, then this will help develop better guidelines for clinical diagnosis and treatment.
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Affiliation(s)
- Jin Liao
- Neurology Department at Chongqing Medical University, Chongqing, China
| | - Xin Tian
- Neurology Department at Chongqing Medical University, Chongqing, China
| | - Hao Wang
- Neurology Department at Chongqing Medical University, Chongqing, China
| | - Zheng Xiao
- Neurology Department at the First Affiliated Hospital of Chongqing Medical University, No. 1 Youyi Street, Yuanjiagang, Yuzhong District, Chongqing, China
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20
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Kim HW, Quan Z, Kim YB, Cheong E, Kim HD, Cho M, Jang J, Yoo YR, Lee JS, Kim JH, Kim YI, Kim DS, Kang HC. Differential effects on sodium current impairments by distinct SCN1A mutations in GABAergic neurons derived from Dravet syndrome patients. Brain Dev 2018; 40:287-298. [PMID: 29295803 DOI: 10.1016/j.braindev.2017.12.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 12/04/2017] [Accepted: 12/04/2017] [Indexed: 01/03/2023]
Abstract
BACKGROUND We investigated how two distinct mutations in SCN1A differentially affect electrophysiological properties of the patient-derived GABAergic neurons and clinical severities in two Dravet syndrome (DS) patients. MATERIALS AND METHODS We established induced pluripotent stem cells from two DS patients with different mutations in SCN1A and subsequently differentiated them into forebrain GABAergic neurons. Functionality of differentiated GABAergic neurons was examined by electrophysiological recordings. RESULTS DS-1 patient had a missense mutation, c.4261G > T [GenBank: NM_006920.4] and DS-2 patient had a nonsense frameshift mutation, c.3576_3580 del TCAAA [GenBank: NM_006920.4]. Clinically, contrary to our expectations, DS-1 patient had more severe symptoms including frequency of seizure episodes and the extent of intellectual ability penetration than DS-2 patient. Electrophysiologic recordings showed significantly lower sodium current density and reduced action potential frequency at strong current injection (>60 pA) in GABAergic neurons derived from both. Intriguingly, unique genetic alterations of SCN1A differentially impacted electrophysiological impairment of the neurons, and the impairment's extent corresponded with the symptomatic severity of the donor from which the iPSCs were derived. CONCLUSION Our results suggest the possibility that patient-derived iPSCs may provide a reliable in vitro system that reflects clinical severities in individuals with DS.
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Affiliation(s)
- Hyun Woo Kim
- Division of Pediatric Neurology, Department of Pediatrics, Severance Children's Hospital, Yonsei University College of Medicine, Yonsei-ro 50-1, Seodaemun-gu, Seoul 03722, Republic of Korea
| | - Zhejiu Quan
- Division of Pediatric Neurology, Department of Pediatrics, Severance Children's Hospital, Yonsei University College of Medicine, Yonsei-ro 50-1, Seodaemun-gu, Seoul 03722, Republic of Korea
| | - Young-Beom Kim
- Department of Physiology, Korea University College of Medicine, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea
| | - Eunji Cheong
- Department of Biotechnology, Yonsei University, Seoul 120-749, Republic of Korea
| | - Heung Dong Kim
- Division of Pediatric Neurology, Department of Pediatrics, Severance Children's Hospital, Yonsei University College of Medicine, Yonsei-ro 50-1, Seodaemun-gu, Seoul 03722, Republic of Korea
| | - Minjung Cho
- Division of Pediatric Neurology, Department of Pediatrics, Severance Children's Hospital, Yonsei University College of Medicine, Yonsei-ro 50-1, Seodaemun-gu, Seoul 03722, Republic of Korea
| | - Jiho Jang
- Department of Physiology, Yonsei University College of Medicine, 50-1 Yonsei-ro, Seodaemun-gu, Seoul 03722, Republic of Korea
| | - Young Rang Yoo
- Department of Biotechnology, BK21 PLUS Project, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea
| | - Joon Soo Lee
- Division of Pediatric Neurology, Department of Pediatrics, Severance Children's Hospital, Yonsei University College of Medicine, Yonsei-ro 50-1, Seodaemun-gu, Seoul 03722, Republic of Korea
| | - Ji Hun Kim
- Division of Pediatric Neurology, Department of Pediatrics, Severance Children's Hospital, Yonsei University College of Medicine, Yonsei-ro 50-1, Seodaemun-gu, Seoul 03722, Republic of Korea
| | - Yang In Kim
- Department of Physiology, Korea University College of Medicine, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea
| | - Dae-Sung Kim
- Department of Biotechnology, BK21 PLUS Project, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea; Department of Pediatrics, Korea University College of Medicine, Guro Hospital, 97 Gurodong-gil, Guro-gu, Seoul 08308, Republic of Korea.
| | - Hoon-Chul Kang
- Division of Pediatric Neurology, Department of Pediatrics, Severance Children's Hospital, Yonsei University College of Medicine, Yonsei-ro 50-1, Seodaemun-gu, Seoul 03722, Republic of Korea.
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21
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de Lange IM, Koudijs MJ, van 't Slot R, Gunning B, Sonsma ACM, van Gemert LJJM, Mulder F, Carbo EC, van Kempen MJA, Verbeek NE, Nijman IJ, Ernst RF, Savelberg SMC, Knoers NVAM, Brilstra EH, Koeleman BPC. Mosaicism of de novo pathogenic SCN1A
variants in epilepsy is a frequent phenomenon that correlates with variable phenotypes. Epilepsia 2018; 59:690-703. [DOI: 10.1111/epi.14021] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/16/2018] [Indexed: 11/28/2022]
Affiliation(s)
- Iris M. de Lange
- Department of Genetics; Center for Molecular Medicine; University Medical Center Utrecht; Utrecht the Netherlands
| | - Marco J. Koudijs
- Department of Genetics; Center for Molecular Medicine; University Medical Center Utrecht; Utrecht the Netherlands
| | - Ruben van 't Slot
- Department of Genetics; Center for Molecular Medicine; University Medical Center Utrecht; Utrecht the Netherlands
| | | | - Anja C. M. Sonsma
- Department of Genetics; Center for Molecular Medicine; University Medical Center Utrecht; Utrecht the Netherlands
| | | | - Flip Mulder
- Department of Genetics; Center for Molecular Medicine; University Medical Center Utrecht; Utrecht the Netherlands
| | - Ellen C. Carbo
- Department of Genetics; Center for Molecular Medicine; University Medical Center Utrecht; Utrecht the Netherlands
| | - Marjan J. A. van Kempen
- Department of Genetics; Center for Molecular Medicine; University Medical Center Utrecht; Utrecht the Netherlands
| | - Nienke E. Verbeek
- Department of Genetics; Center for Molecular Medicine; University Medical Center Utrecht; Utrecht the Netherlands
| | - Isaac J. Nijman
- Department of Genetics; Center for Molecular Medicine; University Medical Center Utrecht; Utrecht the Netherlands
| | - Robert F. Ernst
- Department of Genetics; Center for Molecular Medicine; University Medical Center Utrecht; Utrecht the Netherlands
| | - Sanne M. C. Savelberg
- Department of Genetics; Center for Molecular Medicine; University Medical Center Utrecht; Utrecht the Netherlands
| | - Nine V. A. M. Knoers
- Department of Genetics; Center for Molecular Medicine; University Medical Center Utrecht; Utrecht the Netherlands
| | - Eva H. Brilstra
- Department of Genetics; Center for Molecular Medicine; University Medical Center Utrecht; Utrecht the Netherlands
| | - Bobby P. C. Koeleman
- Department of Genetics; Center for Molecular Medicine; University Medical Center Utrecht; Utrecht the Netherlands
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Abstract
The tragedy of epilepsy emerges from the combination of its high prevalence, impact upon sufferers and their families, and unpredictability. Childhood epilepsies are frequently severe, presenting in infancy with pharmaco-resistant seizures; are often accompanied by debilitating neuropsychiatric and systemic comorbidities; and carry a grave risk of mortality. Here, we review the most current basic science and translational research findings on several of the most catastrophic forms of pediatric epilepsy. We focus largely on genetic epilepsies and the research that is discovering the mechanisms linking disease genes to epilepsy syndromes. We also describe the strides made toward developing novel pharmacological and interventional treatment strategies to treat these disorders. The research reviewed provides hope for a complete understanding of, and eventual cure for, these childhood epilepsy syndromes.
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Affiliation(s)
- MacKenzie A Howard
- Center for Learning and Memory and Department of Neuroscience, University of Texas at Austin, Texas, 78712;
| | - Scott C Baraban
- Epilepsy Research Laboratory in the Department of Neurological Surgery, Weill Institute for Neurosciences, University of California, San Francisco, California 94143;
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23
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Abstract
Episodic ataxia (EA) is a rare neurological condition characterized by recurrent spells of truncal ataxia and incoordination. Five genes (KCNA1, CACNA1A, CACNB4, SLC1A3, and UBR4) have been linked to EA. Despite extensive efforts to genetically diagnose EA, many patients remain still undiagnosed. Whole-exome sequencing was carried out in 39 Korean patients with EA to identify pathogenic mutations of the five known EA genes. We also evaluated 40 candidate genes that cause EA as a secondary phenotype or cerebellar ataxia. Eighteen patients (46%) revealed genetic information useful for establishing a molecular diagnosis of EA. In 11 patients, 16 pathogenic mutations were detected in three EA genes. These included nine mutations in CACNA1A, three in SLC1A3, and four in UBR4. Three patients had mutations in two genes, either CACNA1A and SLC1A3 or CACNA1A and UBR4, suggesting that SLC1A3 and UBR4 may act as genetic modifiers with synergic effects on the abnormal presynaptic activity caused by CACNA1A mutations. In seven patients with negative results for screening of EA genes, potential pathogenic mutations were identified in the candidate genes ATP1A2, SCN1A, TTBK2, TGM6, FGF14, and KCND3. This study demonstrates the genetic heterogeneity of Korean EA, and indicates that whole-exome sequencing may be useful for molecular genetic diagnosis of EA.
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24
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Rare variants of small effect size in neuronal excitability genes influence clinical outcome in Japanese cases of SCN1A truncation-positive Dravet syndrome. PLoS One 2017; 12:e0180485. [PMID: 28686619 PMCID: PMC5501540 DOI: 10.1371/journal.pone.0180485] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Accepted: 06/15/2017] [Indexed: 12/18/2022] Open
Abstract
Dravet syndrome (DS) is a rare, devastating form of childhood epilepsy that is often associated with mutations in the voltage-gated sodium channel gene, SCN1A. There is considerable variability in expressivity within families, as well as among individuals carrying the same primary mutation, suggesting that clinical outcome is modulated by variants at other genes. To identify modifier gene variants that contribute to clinical outcome, we sequenced the exomes of 22 individuals at both ends of a phenotype distribution (i.e., mild and severe cognitive condition). We controlled for variation associated with different mutation types by limiting inclusion to individuals with a de novo truncation mutation resulting in SCN1A haploinsufficiency. We performed tests aimed at identifying 1) single common variants that are enriched in either phenotypic group, 2) sets of common or rare variants aggregated in and around genes associated with clinical outcome, and 3) rare variants in 237 candidate genes associated with neuronal excitability. While our power to identify enrichment of a common variant in either phenotypic group is limited as a result of the rarity of mild phenotypes in individuals with SCN1A truncation variants, our top candidates did not map to functional regions of genes, or in genes that are known to be associated with neurological pathways. In contrast, we found a statistically-significant excess of rare variants predicted to be damaging and of small effect size in genes associated with neuronal excitability in severely affected individuals. A KCNQ2 variant previously associated with benign neonatal seizures is present in 3 of 12 individuals in the severe category. To compare our results with the healthy population, we performed a similar analysis on whole exome sequencing data from 70 Japanese individuals in the 1000 genomes project. Interestingly, the frequency of rare damaging variants in the same set of neuronal excitability genes in healthy individuals is nearly as high as in severely affected individuals. Rather than a single common gene/variant modifying clinical outcome in SCN1A-related epilepsies, our results point to the cumulative effect of rare variants with little to no measurable phenotypic effect (i.e., typical genetic background) unless present in combination with a disease-causing truncation mutation in SCN1A.
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25
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Abstract
Dravet syndrome is one of the most severe epilepsy syndromes of early childhood, and it comes with very high morbidity and mortality. The typical presentation is characterized by hemiclonic or generalized clonic seizures triggered by fever during the first year of life, followed by myoclonic, absence, focal and generalized tonic-clonic seizures. Non-convulsive status epilepticus and epileptic encephalopathy are common. Development is normal in the first year of life, but most individuals eventually suffer from intellectual impairment. Dravet syndrome is associated with mutations in the sodium channel alpha1 subunit gene (SCN1A) in 70-80% of individuals. SCN1A mutation results in inhibition of the GABAergic inhibitory interneurons, leading to excessive neuronal excitation. The "interneuron hypothesis" is the current most accepted pathophysiological mechanism of Dravet syndrome. The mortality rate is increased significantly in Dravet syndrome. Ataxia, a characteristic crouched gait and Parkinson's symptoms may develop in some individuals. It is likely that Dravet syndrome is underdiagnosed in adults with treatment-resistant epilepsy. Early diagnosis is important to avoid anti-seizure medications that exacerbate seizures.
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26
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Huang Y, Xiao H, Qin X, Nong Y, Zou D, Wu Y. The genetic relationship between epilepsy and hemiplegic migraine. Neuropsychiatr Dis Treat 2017; 13:1175-1179. [PMID: 28479855 PMCID: PMC5411172 DOI: 10.2147/ndt.s132451] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Epilepsy and migraine are common diseases of the nervous system and share genetic and pathophysiological mechanisms. Familial hemiplegic migraine is an autosomal dominant disease. It is often used as a model of migraine. Four genes often contain one or more mutations in both epilepsy and hemiplegic migraine patients (ie, CACNA1A, ATP1A2, SCN1A, and PRRT2). A better understanding of the shared genetics of epilepsy and hemiplegic migraine may reveal new strategic directions for research and treatment of both the disorders.
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Affiliation(s)
- Yiqing Huang
- Department of Neurology, Guigang City People's Hospital and the Eighth Affiliated Hospital of Guangxi Medical University, Guigang, People's Republic of China
| | - Hai Xiao
- Department of Neurology, Guigang City People's Hospital and the Eighth Affiliated Hospital of Guangxi Medical University, Guigang, People's Republic of China
| | - Xingyue Qin
- Department of Neurology, Guigang City People's Hospital and the Eighth Affiliated Hospital of Guangxi Medical University, Guigang, People's Republic of China
| | - Yuan Nong
- Department of Neurology, Guigang City People's Hospital and the Eighth Affiliated Hospital of Guangxi Medical University, Guigang, People's Republic of China
| | - Donghua Zou
- Department of Neurology, The Fifth Affiliated Hospital of Guangxi Medical University and the First People's Hospital of Nanning, Nanning, People's Republic of China
| | - Yuan Wu
- Department of Neurology, The First Affiliated Hospital of Guangxi Medical University, Nanning, People's Republic of China
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27
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Ishii A, Watkins JC, Chen D, Hirose S, Hammer MF. Clinical implications of SCN1A missense and truncation variants in a large Japanese cohort with Dravet syndrome. Epilepsia 2016; 58:282-290. [PMID: 28012175 DOI: 10.1111/epi.13639] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/14/2016] [Indexed: 12/28/2022]
Abstract
OBJECTIVE Two major classes of SCN1A variants are associated with Dravet syndrome (DS): those that result in haploinsufficiency (truncating) and those that result in an amino acid substitution (missense). The aim of this retrospective study was to describe the first large cohort of Japanese patients with SCN1A mutation-positive DS (n = 285), and investigate the relationship between variant (type and position) and clinical expression and response to treatment. METHODS We sequenced all exons and intron-exon boundaries of SCN1A in our cohort, investigated differences in the distribution of truncating and missense variants, tested for associations between variant type and phenotype, and compared these patterns with those of cohorts with milder epilepsy and healthy individuals. RESULTS Unlike truncation variants, missense variants are found at higher density in the S4 voltage sensor and pore loops and at lower density in the domain I-II and II-III linkers and the first three segments of domain II. Relative to healthy individuals, there is an increased frequency of truncating (but not missense) variants in the noncoding C-terminus. The rate of cognitive decline is more rapid for patients with truncation variants regardless of age at seizure onset, whereas age at onset is a predictor of the rate of cognitive decline for patients with missense variants. SIGNIFICANCE We found significant differences in the distribution of truncating and missense variants across the SCN1A sequence among healthy individuals, patients with DS, and those with milder forms of SCN1A-variant positive epilepsy. Testing for associations with phenotype revealed that variant type can be predictive of rate of cognitive decline. Analysis of descriptive medication data suggests that in addition to conventional drug therapy in DS, bromide, clonazepam and topiramate may reduce seizure frequency.
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Affiliation(s)
- Atsushi Ishii
- ARL Division of Biotechnology, University of Arizona, Tucson, Arizona, U.S.A.,Department of Pediatrics, School of Medicine and Central Research Institute for the Molecular Pathogeneses of Epilepsy, Fukuoka University, Fukuoka, Japan
| | - Joseph C Watkins
- Department of Mathematics, University of Arizona, Tucson, Arizona, U.S.A
| | - Debbie Chen
- ARL Division of Biotechnology, University of Arizona, Tucson, Arizona, U.S.A
| | - Shinichi Hirose
- Department of Pediatrics, School of Medicine and Central Research Institute for the Molecular Pathogeneses of Epilepsy, Fukuoka University, Fukuoka, Japan
| | - Michael F Hammer
- ARL Division of Biotechnology, University of Arizona, Tucson, Arizona, U.S.A.,Department of Neurology, University of Arizona, Tucson, Arizona, U.S.A
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28
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From focal epilepsy to Dravet syndrome--Heterogeneity of the phenotype due to SCN1A mutations of the p.Arg1596 amino acid residue in the Nav1.1 subunit. Neurol Neurochir Pol 2015; 49:258-66. [PMID: 26188943 DOI: 10.1016/j.pjnns.2015.06.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Revised: 05/28/2015] [Accepted: 06/11/2015] [Indexed: 11/20/2022]
Abstract
OBJECTIVE The aim of this study was to analyze the intra-/interfamilial phenotypic heterogeneity due to variants at the highly evolutionary conservative p.Arg1596 residue in the Nav1.1 subunit. MATERIALS/PARTICIPANTS Among patients referred for analysis of the SCN1A gene one recurrent, heritable mutation was found in families enrolled into the study. Probands from those families even clinically diagnosed with atypical Dravet syndrome (DS), generalized epilepsy with febrile seizures plus (GEFS+), and focal epilepsy, had heterozygous p.Arg1596 His/Cys missense substitutions, c.4787G>T and c.4786C>T in the SCN1A gene. METHOD Full clinical evaluation, including cognitive development, neurological examination, EEGs, MRI was performed in probands and affected family members in developmental age. The whole SCN1A gene sequencing was performed for all probands. The exon 25, where the identified missense substitutions are localized, was directly analyzed for the other family members. RESULTS Mutation of the SCN1A p.1596Arg was identified in three families, in one case substitution p.Arg1596Cys and in two cases p.Arg1596His. Both mutations were previously described as pathogenic and causative for DS, GEFS+ and focal epilepsy. Spectrum of phenotypes among presented families with p.Arg1596 mutations shows heterogeneity ranged from asymptomatic cases, through FS and FS+ to GEFS+/Panayiotopoulos syndrome and epilepsies with and without febrile seizures, and epileptic encephalopathy such as DS. Phenotypes differ among patients displaying both focal and generalized epilepsies. Some patients demonstrated additionally Asperger syndrome and ataxia. CONCLUSION Clinical picture heterogeneity of the patients carrying mutation of the same residue indicates the involvement of the other factors influencing the SCN1A gene mutations' penetrance.
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Cooper DN, Krawczak M, Polychronakos C, Tyler-Smith C, Kehrer-Sawatzki H. Where genotype is not predictive of phenotype: towards an understanding of the molecular basis of reduced penetrance in human inherited disease. Hum Genet 2013; 132:1077-130. [PMID: 23820649 PMCID: PMC3778950 DOI: 10.1007/s00439-013-1331-2] [Citation(s) in RCA: 407] [Impact Index Per Article: 37.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2013] [Accepted: 06/15/2013] [Indexed: 02/06/2023]
Abstract
Some individuals with a particular disease-causing mutation or genotype fail to express most if not all features of the disease in question, a phenomenon that is known as 'reduced (or incomplete) penetrance'. Reduced penetrance is not uncommon; indeed, there are many known examples of 'disease-causing mutations' that fail to cause disease in at least a proportion of the individuals who carry them. Reduced penetrance may therefore explain not only why genetic diseases are occasionally transmitted through unaffected parents, but also why healthy individuals can harbour quite large numbers of potentially disadvantageous variants in their genomes without suffering any obvious ill effects. Reduced penetrance can be a function of the specific mutation(s) involved or of allele dosage. It may also result from differential allelic expression, copy number variation or the modulating influence of additional genetic variants in cis or in trans. The penetrance of some pathogenic genotypes is known to be age- and/or sex-dependent. Variable penetrance may also reflect the action of unlinked modifier genes, epigenetic changes or environmental factors. At least in some cases, complete penetrance appears to require the presence of one or more genetic variants at other loci. In this review, we summarize the evidence for reduced penetrance being a widespread phenomenon in human genetics and explore some of the molecular mechanisms that may help to explain this enigmatic characteristic of human inherited disease.
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Affiliation(s)
- David N. Cooper
- Institute of Medical Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff, CF14 4XN UK
| | - Michael Krawczak
- Institute of Medical Informatics and Statistics, Christian-Albrechts University, 24105 Kiel, Germany
| | | | - Chris Tyler-Smith
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, CB10 1SA UK
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30
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The SCN1A gene variants and epileptic encephalopathies. J Hum Genet 2013; 58:573-80. [PMID: 23884151 DOI: 10.1038/jhg.2013.77] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2013] [Revised: 06/24/2013] [Accepted: 07/03/2013] [Indexed: 02/02/2023]
Abstract
The voltage-gated sodium channels are fundamental units that evoke the action potential in excitable cells such as neurons. These channels are integral membrane proteins typically consisting of one α-subunit, which forms the larger central pore of the channel, and two smaller auxiliary β-subunits, which modulate the channel functions. Genetic alterations in the SCN1A gene coding for the α-subunit of the neuronal voltage-gated sodium ion channel, type 1 (NaV 1.1), is associated with a spectrum of seizure-related disorders in human, ranging from a relatively milder form of febrile seizures to a more severe epileptic condition known as the Dravet syndrome. Among the epilepsy genes, the SCN1A gene perhaps known to have the largest number of disease-associated alleles. Here we present a meta-analysis on the SCN1A gene variants and provide comprehensive information on epilepsy-associated gene variants, their frequency, the predicted effect on the protein, the ethnicity of the affected along with the inheritance pattern and the associated epileptic phenotype. We also summarize our current understanding on the pathophysiology of the SCN1A gene defects, disease mechanism, genetic modifiers and their clinical and diagnostic relevance.
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