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Bazgir A, Agha Gholizadeh M, Kahani SM, Tavasoli AR, Garshasbi M. Identification of a Novel Homozygous GLS Gene Variant Associated with Developmental and Epileptic Encephalopathy (DEE) Type 71. Neurogenetics 2024; 25:225-232. [PMID: 38622440 DOI: 10.1007/s10048-024-00753-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2024] [Accepted: 03/06/2024] [Indexed: 04/17/2024]
Abstract
Developmental and epileptic encephalopathy (DEEs) (OMIM#618,328) is characterized by seizures, hypotonia, and brain abnormalities, often arising from mutations in genes crucial for brain function. Among these genes, GLS stands out due to its vital role in the central nervous system (CNS), with homozygous variants potentially causing DEE type 71. Using Whole Exome Sequencing (WES) on a patient exhibiting symptoms of epileptic encephalopathy, we identified a novel homozygous variant, NM_014905.5:c.1849G > T; p.(Asp617Tyr), in the GLS gene. The 5-year-old patient, born to consanguineous parents, presented with developmental delay, encephalopathy, frequent seizures, and hypotonia. Sanger sequencing further validated the GLS gene variant in both the patient and his family. Furthermore, our bioinformatics analysis indicated that this missense variant could lead to alteration of splicing, resulting in the activation of a cryptic donor site and potentially causing loss of protein function. Our finding highlights the pathogenic significance of the GLS gene, particularly in the context of brain disorders, specifically DEE71.
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Affiliation(s)
- Afsaneh Bazgir
- Department of Medical Genetics, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
- PardisGene Company, Tehran, Iran
| | - Mehdi Agha Gholizadeh
- Department of Medical Genetics, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
- PardisGene Company, Tehran, Iran
| | - Seyyed Mohammad Kahani
- Department of Medical Genetics, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
- PardisGene Company, Tehran, Iran
| | - Ali Reza Tavasoli
- Division of Pediatric Neurology, Myelin Disorders Clinic, Children's Medical Center, Tehran University of Medical Sciences, Tehran, Iran
- Neurology Division, Barrow Neurological Institute, Phoenix Children's Hospital, Phoenix, AZ, USA
| | - Masoud Garshasbi
- Department of Medical Genetics, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran.
- Department of Medical Genetics, DeNA Laboratory, Tehran, Iran.
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Dong R, Jin R, Zhang H, Zhang H, Xue M, Li Y, Zhang K, Lv Y, Li X, Liu Y, Gai Z. Genotypic and phenotypic characteristics of sodium channel-associated epilepsy in Chinese population. J Hum Genet 2024:10.1038/s10038-024-01257-2. [PMID: 38880818 DOI: 10.1038/s10038-024-01257-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2023] [Revised: 04/27/2024] [Accepted: 04/30/2024] [Indexed: 06/18/2024]
Abstract
Variants in voltage-gated sodium channel (VGSC) genes are implicated in seizures, epilepsy, and neurodevelopmental disorders, constituting a significant aspect of hereditary epilepsy in the Chinese population. Through retrospective analysis utilizing next-generation sequencing (NGS), we examined the genotypes and phenotypes of VGSC-related epilepsy cases from a cohort of 691 epilepsy subjects. Our findings revealed that 5.1% of subjects harbored VGSC variants, specifically 22 with SCN1A, 9 with SCN2A, 1 with SCN8A, and 3 with SCN1B variants; no SCN3A variants were detected. Among these, 14 variants were previously reported, while 21 were newly identified. SCN1A variant carriers predominantly presented with Dravet Syndrome (DS) and Genetic Epilepsy with Febrile Seizures Plus (GEFS + ), featuring a heightened sensitivity to fever-induced seizures. Statistically significant disparities emerged between the SCN1A-DS and SCN1A-GEFS+ groups concerning seizure onset and genetic diagnosis age, incidence of status epilepticus, mental retardation, anti-seizure medication (ASM) responsiveness, and familial history. Notably, subjects with SCN1A variants affecting the protein's pore region experienced more frequent cluster seizures. All SCN2A variants were of de novo origin, and 88.9% of individuals with SCN2A variations exhibited cluster seizures. This research reveals a significant association between variations in VGSC-related genes and the clinical phenotype diversity of epilepsy subjects in China, emphasizing the pivotal role of NGS screening in establishing accurate disease diagnoses and guiding the selection of ASM.
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Affiliation(s)
- Rui Dong
- Pediatric Research Institute, Children's Hospital Affiliated to Shandong University (Jinan Children's Hospital), Jinan, China
- Shandong Provincial Clinical Research Center for Children's Health and Disease, Jinan, China
| | - Ruifeng Jin
- Shandong Provincial Clinical Research Center for Children's Health and Disease, Jinan, China
- Department of neurology, Children's Hospital Affiliated to Shandong University (Jinan Children's Hospital), Jinan, China
| | - Hongwei Zhang
- Shandong Provincial Clinical Research Center for Children's Health and Disease, Jinan, China
- Department of neurology, Children's Hospital Affiliated to Shandong University (Jinan Children's Hospital), Jinan, China
| | - Haiyan Zhang
- Pediatric Research Institute, Children's Hospital Affiliated to Shandong University (Jinan Children's Hospital), Jinan, China
- Shandong Provincial Clinical Research Center for Children's Health and Disease, Jinan, China
| | - Min Xue
- Pediatric Research Institute, Children's Hospital Affiliated to Shandong University (Jinan Children's Hospital), Jinan, China
- Shandong Provincial Clinical Research Center for Children's Health and Disease, Jinan, China
| | - Yue Li
- Pediatric Research Institute, Children's Hospital Affiliated to Shandong University (Jinan Children's Hospital), Jinan, China
- Shandong Provincial Clinical Research Center for Children's Health and Disease, Jinan, China
| | - Kaihui Zhang
- Pediatric Research Institute, Children's Hospital Affiliated to Shandong University (Jinan Children's Hospital), Jinan, China
- Shandong Provincial Clinical Research Center for Children's Health and Disease, Jinan, China
| | - Yuqiang Lv
- Pediatric Research Institute, Children's Hospital Affiliated to Shandong University (Jinan Children's Hospital), Jinan, China
- Shandong Provincial Clinical Research Center for Children's Health and Disease, Jinan, China
| | - Xiaoying Li
- Shandong Provincial Clinical Research Center for Children's Health and Disease, Jinan, China.
- Neonatology department, Children's Hospital Affiliated to Shandong University (Jinan Children's Hospital), Jinan, China.
| | - Yi Liu
- Pediatric Research Institute, Children's Hospital Affiliated to Shandong University (Jinan Children's Hospital), Jinan, China.
- Shandong Provincial Clinical Research Center for Children's Health and Disease, Jinan, China.
| | - Zhongtao Gai
- Pediatric Research Institute, Children's Hospital Affiliated to Shandong University (Jinan Children's Hospital), Jinan, China
- Shandong Provincial Clinical Research Center for Children's Health and Disease, Jinan, China
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Lin S, Gade AR, Wang HG, Niemeyer JE, Galante A, DiStefano I, Towers P, Nunez J, Schwartz TH, Rajadhyaksha AM, Pitt GS. Interneuron FGF13 regulates seizure susceptibility via a sodium channel-independent mechanism. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.18.590019. [PMID: 38659789 PMCID: PMC11042350 DOI: 10.1101/2024.04.18.590019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
Developmental and Epileptic Encephalopathies (DEEs), a class of devastating neurological disorders characterized by recurrent seizures and exacerbated by disruptions to excitatory/inhibitory balance in the brain, are commonly caused by mutations in ion channels. Disruption of, or variants in, FGF13 were implicated as causal for a set of DEEs, but the underlying mechanisms were clouded because FGF13 is expressed in both excitatory and inhibitory neurons, FGF13 undergoes extensive alternative splicing producing multiple isoforms with distinct functions, and the overall roles of FGF13 in neurons are incompletely cataloged. To overcome these challenges, we generated a set of novel cell type-specific conditional knockout mice. Interneuron-targeted deletion of Fgf13 led to perinatal mortality associated with extensive seizures and impaired the hippocampal inhibitory/excitatory balance while excitatory neuron-targeted deletion of Fgf13 caused no detectable seizures and no survival deficits. While best studied as a voltage-gated sodium channel (Nav) regulator, we observed no effect of Fgf13 ablation in interneurons on Navs but rather a marked reduction in K+ channel currents. Re-expressing different Fgf13 splice isoforms could partially rescue deficits in interneuron excitability and restore K+ channel current amplitude. These results enhance our understanding of the molecular mechanisms that drive the pathogenesis of Fgf13-related seizures and expand our understanding of FGF13 functions in different neuron subsets.
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Affiliation(s)
- Susan Lin
- Cardiovascular Research Institute, Weill Cornell Medicine, New York, NY
| | - Aravind R. Gade
- Cardiovascular Research Institute, Weill Cornell Medicine, New York, NY
| | - Hong-Gang Wang
- Cardiovascular Research Institute, Weill Cornell Medicine, New York, NY
| | - James E. Niemeyer
- Department of Neurological Surgery and Brain and Mind Research Institute, Weill Cornell Medicine of Cornell University, New York Presbyterian Hospital, New York, NY
| | - Allison Galante
- Cardiovascular Research Institute, Weill Cornell Medicine, New York, NY
| | | | - Patrick Towers
- Cardiovascular Research Institute, Weill Cornell Medicine, New York, NY
| | - Jorge Nunez
- Cardiovascular Research Institute, Weill Cornell Medicine, New York, NY
| | - Theodore H. Schwartz
- Department of Neurological Surgery and Brain and Mind Research Institute, Weill Cornell Medicine of Cornell University, New York Presbyterian Hospital, New York, NY
| | - Anjali M. Rajadhyaksha
- Department of Pediatrics, Division of Pediatric Neurology, Weill Cornell Medicine, New York, NY; Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY
| | - Geoffrey S. Pitt
- Cardiovascular Research Institute, Weill Cornell Medicine, New York, NY
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Weiler M, Stieger KC, Shroff K, Klein JP, Wood WH, Zhang Y, Chandrasekaran P, Lehrmann E, Camandola S, Long JM, Mattson MP, Becker KG, Rapp PR. Transcriptional changes in the rat brain induced by repetitive transcranial magnetic stimulation. Front Hum Neurosci 2023; 17:1215291. [PMID: 38021223 PMCID: PMC10679736 DOI: 10.3389/fnhum.2023.1215291] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Accepted: 10/03/2023] [Indexed: 12/01/2023] Open
Abstract
Introduction Transcranial Magnetic Stimulation (TMS) is a noninvasive technique that uses pulsed magnetic fields to affect the physiology of the brain and central nervous system. Repetitive TMS (rTMS) has been used to study and treat several neurological conditions, but its complex molecular basis is largely unexplored. Methods Utilizing three experimental rat models (in vitro, ex vivo, and in vivo) and employing genome-wide microarray analysis, our study reveals the extensive impact of rTMS treatment on gene expression patterns. Results These effects are observed across various stimulation protocols, in diverse tissues, and are influenced by time and age. Notably, rTMS-induced alterations in gene expression span a wide range of biological pathways, such as glutamatergic, GABAergic, and anti-inflammatory pathways, ion channels, myelination, mitochondrial energetics, multiple neuron-and synapse-specific genes. Discussion This comprehensive transcriptional analysis induced by rTMS stimulation serves as a foundational characterization for subsequent experimental investigations and the exploration of potential clinical applications.
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Affiliation(s)
- Marina Weiler
- Laboratory of Behavioral Neuroscience, National Institute on Aging, National Institutes of Health, Baltimore, MD, United States
| | - Kevin C. Stieger
- Laboratory of Behavioral Neuroscience, National Institute on Aging, National Institutes of Health, Baltimore, MD, United States
| | - Kavisha Shroff
- Laboratory of Genetics and Genomics, National Institute on Aging, National Institutes of Health, Baltimore, MD, United States
| | - Jessie P. Klein
- Laboratory of Genetics and Genomics, National Institute on Aging, National Institutes of Health, Baltimore, MD, United States
| | - William H. Wood
- Laboratory of Genetics and Genomics, National Institute on Aging, National Institutes of Health, Baltimore, MD, United States
| | - Yongqing Zhang
- Laboratory of Genetics and Genomics, National Institute on Aging, National Institutes of Health, Baltimore, MD, United States
| | - Prabha Chandrasekaran
- Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, MD, United States
| | - Elin Lehrmann
- Laboratory of Genetics and Genomics, National Institute on Aging, National Institutes of Health, Baltimore, MD, United States
| | - Simonetta Camandola
- Laboratory of Neurosciences, National Institute on Aging, National Institutes of Health, Baltimore, MD, United States
| | - Jeffrey M. Long
- Laboratory of Behavioral Neuroscience, National Institute on Aging, National Institutes of Health, Baltimore, MD, United States
| | - Mark P. Mattson
- Laboratory of Neurosciences, National Institute on Aging, National Institutes of Health, Baltimore, MD, United States
| | - Kevin G. Becker
- Laboratory of Genetics and Genomics, National Institute on Aging, National Institutes of Health, Baltimore, MD, United States
| | - Peter R. Rapp
- Laboratory of Behavioral Neuroscience, National Institute on Aging, National Institutes of Health, Baltimore, MD, United States
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Chen C, Ziobro J, Robinson-Cooper L, Hodges SL, Chen Y, Edokobi N, Lopez-Santiago L, Habig K, Moore C, Minton J, Bramson S, Scheuing C, Daddo N, Štěrbová K, Weckhuysen S, Parent JM, Isom LL. Epilepsy and sudden unexpected death in epilepsy in a mouse model of human SCN1B-linked developmental and epileptic encephalopathy. Brain Commun 2023; 5:fcad283. [PMID: 38425576 PMCID: PMC10903178 DOI: 10.1093/braincomms/fcad283] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Revised: 07/13/2023] [Accepted: 10/18/2023] [Indexed: 03/02/2024] Open
Abstract
Voltage-gated sodium channel β1 subunits are essential proteins that regulate excitability. They modulate sodium and potassium currents, function as cell adhesion molecules and regulate gene transcription following regulated intramembrane proteolysis. Biallelic pathogenic variants in SCN1B, encoding β1, are linked to developmental and epileptic encephalopathy 52, with clinical features overlapping Dravet syndrome. A recessive variant, SCN1B-c.265C>T, predicting SCN1B-p.R89C, was homozygous in two children of a non-consanguineous family. One child was diagnosed with Dravet syndrome, while the other had a milder phenotype. We identified an unrelated biallelic SCN1B-c.265C>T patient with a clinically more severe phenotype than Dravet syndrome. We used CRISPR/Cas9 to knock-in SCN1B-p.R89C to the mouse Scn1b locus (Scn1bR89/C89). We then rederived the line on the C57BL/6J background to allow comparisons between Scn1bR89/R89 and Scn1bC89/C89 littermates with Scn1b+/+ and Scn1b-/- mice, which are congenic on C57BL/6J, to determine whether the SCN1B-c.265C>T variant results in loss-of-function. Scn1bC89/C89 mice have normal body weights and ∼20% premature mortality, compared with severely reduced body weight and 100% mortality in Scn1b-/- mice. β1-p.R89C polypeptides are expressed in brain at comparable levels to wild type. In heterologous cells, β1-p.R89C localizes to the plasma membrane and undergoes regulated intramembrane proteolysis similar to wild type. Heterologous expression of β1-p.R89C results in sodium channel α subunit subtype specific effects on sodium current. mRNA abundance of Scn2a, Scn3a, Scn5a and Scn1b was increased in Scn1bC89/C89 somatosensory cortex, with no changes in Scn1a. In contrast, Scn1b-/- mouse somatosensory cortex is haploinsufficient for Scn1a, suggesting an additive mechanism for the severity of the null model via disrupted regulation of another Dravet syndrome gene. Scn1bC89/C89 mice are more susceptible to hyperthermia-induced seizures at post-natal Day 15 compared with Scn1bR89/R89 littermates. EEG recordings detected epileptic discharges in young adult Scn1bC89/C89 mice that coincided with convulsive seizures and myoclonic jerks. We compared seizure frequency and duration in a subset of adult Scn1bC89/C89 mice that had been exposed to hyperthermia at post-natal Day 15 versus a subset that were not hyperthermia exposed. No differences in spontaneous seizures were detected between groups. For both groups, the spontaneous seizure pattern was diurnal, occurring with higher frequency during the dark cycle. This work suggests that the SCN1B-c.265C>T variant does not result in complete loss-of-function. Scn1bC89/C89 mice more accurately model SCN1B-linked variants with incomplete loss-of-function compared with Scn1b-/- mice, which model complete loss-of-function, and thus add to our understanding of disease mechanisms as well as our ability to develop new therapeutic strategies.
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Affiliation(s)
- Chunling Chen
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Julie Ziobro
- Department of Pediatrics, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | | | - Samantha L Hodges
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Yan Chen
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Nnamdi Edokobi
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Luis Lopez-Santiago
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Karl Habig
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Chloe Moore
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Joe Minton
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Sabrina Bramson
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Caroline Scheuing
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Noor Daddo
- Department of Neurology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Katalin Štěrbová
- Department of Pediatric Neurology, Charles University and Motol Hospital, V Úvalu 84, 150 06 Prague 5, Czech Republic
| | - Sarah Weckhuysen
- Applied & Translational Neurogenomics Group, VIB Center for Molecular Neurology, VIB, Universiteitsplein 1 B-2610 Antwerpen, Belgium
- Translational Neurosciences, Faculty of Medicine and Health Science, University of Antwerp, Universiteitsplein 1 B-2610 Antwerpen, Belgium
- Department of Neurology, Antwerp University Hospital, Universiteitsplein 1B-2610 Antwerpen, Belgium
- µNEURO Research Centre of Excellence, University of Antwerp, Universiteitsplein 1B-2610 Antwerpen, Belgium
| | - Jack M Parent
- Department of Neurology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
- Michigan Neuroscience Institute, University of Michigan Medical School, Ann Arbor, MI 48109, USA
- Department of Neurology, VA Ann Arbor Healthcare System, Ann Arbor, MI 48105, USA
| | - Lori L Isom
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
- Department of Neurology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
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Vincent A, Chu NT, Shah A, Avanthika C, Jhaveri S, Singh K, Limaye OM, Boddu H. Sudden Infant Death Syndrome: Risk Factors and Newer Risk Reduction Strategies. Cureus 2023; 15:e40572. [PMID: 37465778 PMCID: PMC10351748 DOI: 10.7759/cureus.40572] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/17/2023] [Indexed: 07/20/2023] Open
Abstract
Sudden infant death syndrome (SIDS) continues to be one of the top causes of infant death in the U.S. Despite significant public health initiatives focused on high-risk populations to enhance sleep environments and techniques. The SIDS rate has remained stable in recent years. Risk factors and newer risk reduction strategies for SIDS are the focus of this review article. We conducted a comprehensive literature search on Medline, Cochrane, Embase, and Google Scholar until July 2022. The following search strings and Medical Subject Heading (MeSH) terms were used: "SIDS," "Sudden Infant Death" and "SUID". We explored the literature on SIDS for its epidemiology, pathophysiology, the role of various etiologies and their influence, associated complications leading to SIDS, and preventive and treatment modalities. Despite a more than 50% drop-in rates since the start of the "Back to Sleep" campaign in 1994, sudden infant death syndrome (SIDS) continues to be the top cause of post-neonatal mortality in the United States, despite continued educational initiatives that support safe sleep and other risk reduction strategies. The new American Academy of Pediatrics guidelines for lowering the risk of SIDS include a lot of emphasis on sleeping habits, bedding, and environment but also include elements that are frequently ignored (i.e., prenatal care, smoking, alcohol and drug use, and childhood vaccinations). This study highlights these less-frequently discussed aspects and identifies treatments that have produced beneficial behavioral shifts that benefit newborns as well as their mothers' health and wellbeing.
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Affiliation(s)
- Anita Vincent
- Medicine and Surgery, Karnataka Institute of Medical Sciences, Hubli, IND
| | - Ngan Thy Chu
- Paediatrics, City Children's Hospital, Ho Chi Minh city, VNM
| | - Aashka Shah
- Paediatrics and Child Health, Pramukhswami Medical College, Karamsad, Anand, IND
| | - Chaithanya Avanthika
- Pediatrics, Icahn School of Medicine at Mount Sinai, Queens Hospital Center, New York City, USA
- Medicine and Surgery, Karnataka Institute of Medical Sciences, Hubli, IND
| | - Sharan Jhaveri
- Medicine and Surgery, Smt. Nathiba Hargovandas Lakhmichand Municipal Medical College (NHLMMC), Ahmedabad, IND
| | - Kunika Singh
- Paediatrics, Xinjiang Medical University, Xinjiang, CHN
| | - Om M Limaye
- Paediatrics, Lokmanya Tilak Municipal Medical College and Sion Hospital, Mumbai, IND
| | - Himasaila Boddu
- Paediatrics, Dr. Pinnamaneni Siddartha Institute of Medical Sciences and Research Foundation, Krishna, IND
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Alghamdi MA, Al-Eitan LN, Asiri A, Rababa'h DM, Alqahtani SA, Aldarami MS, Alsaeedi MA, Almuidh RS, Alzahrani AA, Sakah AH, El Nashar EM, Otaif MY, Abdel Ghaffar NF. Association of sodium voltage-gated channel genes polymorphisms with epilepsy risk and prognosis in the Saudi population. Ann Med 2022; 54:1938-1951. [PMID: 35801810 PMCID: PMC9367647 DOI: 10.1080/07853890.2022.2096257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
BACKGROUND Epilepsy is a heterogeneous complex condition that involve the human brain. Genetic predisposition to epilepsy is a fundamental factor of the disorder aetiology. The sodium voltage-gated channel (SCN) genes variants are critical biomarker for the epilepsy development and progression. In this study, we aimed to investigate the association of several SNCs genetic polymorphisms with epilepsy risk and their intrudance of the disease prognosis. METHODS Blood samples were withdrawn from 296 Epilepsy patients in addition to 293 healthy matched participants prior to DNA extraction. PCR-sequencing was used for genotyping analysis. Genotyping outputs were then statistically analysed for genotype/phenotype evaluation. RESULTS Within SCN1A gene we found that the rs6432861 (p = 0.014) was in correlation with the risk of epilepsy. In addition, both rs4667485 and rs1469649 of SCN2A gene were significantly correlated to epilepsy risk for both allelic (4e-4 and 1e-3) and genotypic (1e-3 and 5e-3). Moreover, the haplotype analysis showed that the GATGCTCGGTTTCGCTACGCA haplotype of SCN2A gene was significantly related to epilepsy increased risk, p = 6e-3, OR (CI) = 2.02 (1.23-3.31). In relevant to our finding, many of the investigated SCNs variants in the current study were related to several clinical features of epilepsy. CONCLUSION In light of our results, we infer that SCN genes polymorphisms are strong candidates for epilepsy development and progression. Furthermore, these variant are essential for the disorder prognosis and medications outcomes.Key MessagesGenetic polymorphisms of sodium channels SCN1A, SCN2A and SCN3A were found to be associated with the risk of epilepsy.SCN1B polymorphisms were found to be correlated to epilepsy reduced risk.SCNs variants are involved in the epilepsy prognosis and response to treatment.
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Affiliation(s)
- Mansour A Alghamdi
- Department of Anatomy, College of Medicine, King Khalid University, Abha, Saudi Arabia.,Genomics and Personalized Medicine Unit, College of Medicine, King Khalid University, Abha, Saudi Arabia
| | - Laith N Al-Eitan
- Department of Applied Biological Sciences, Jordan University of Science and Technology, Irbid, Jordan.,Department of Biotechnology and Genetic Engineering, Jordan University of Science and Technology, Irbid, Jordan
| | - Ashwag Asiri
- Department of Child Health, College of Medicine, King Khalid University, Abha, Saudi Arabia
| | - Doaa M Rababa'h
- Department of Applied Biological Sciences, Jordan University of Science and Technology, Irbid, Jordan
| | - Sultan A Alqahtani
- Neurology Department, Neuroscience Centre, King Faisal Specialist Hospital & Research Center, Riyadh, Saudi Arabia
| | - Mohammed S Aldarami
- Neurology Department, Neuroscience Centre, King Faisal Specialist Hospital & Research Center, Riyadh, Saudi Arabia
| | - Manar A Alsaeedi
- Neurology Department, Neuroscience Centre, King Faisal Specialist Hospital & Research Center, Riyadh, Saudi Arabia
| | - Raghad S Almuidh
- Neurology Department, Neuroscience Centre, King Faisal Specialist Hospital & Research Center, Riyadh, Saudi Arabia
| | - Abdulbari A Alzahrani
- Neurology Department, Neuroscience Centre, King Faisal Specialist Hospital & Research Center, Riyadh, Saudi Arabia
| | - Ahmad H Sakah
- College of Medicine, Alfaisal University, Riyadh, Saudi Arabia
| | - Eman Mohamad El Nashar
- Department of Anatomy, College of Medicine, King Khalid University, Abha, Saudi Arabia.,Department of Histology and Cell Biology, Faculty of Medicine, Benha University, Benha, Egypt
| | - Mansour Y Otaif
- Department of Pediatric, Neurology section, Abha Maternity and Childern Hospital, Abha, Saudi Arabia
| | - Nawal F Abdel Ghaffar
- Neurology Department, Kasr Al Ainy Hospital, Faculty of Medicine, Cairo University, Giza, Egypt.,Neurology Department, Aseer Central Hospital, Abha, Saudi Arabia
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8
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Grinton BE, Robertson E, Fearnley LG, Scheffer IE, Marson AG, O'Brien TJ, Pickrell WO, Rees MI, Sisodiya SM, Balding DJ, Bennett MF, Bahlo M, Berkovic SF, Oliver KL. A founder event causing a dominant childhood epilepsy survives 800 years through weak selective pressure. Am J Hum Genet 2022; 109:2080-2087. [PMID: 36288729 PMCID: PMC9674963 DOI: 10.1016/j.ajhg.2022.10.004] [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: 05/11/2022] [Accepted: 10/03/2022] [Indexed: 01/26/2023] Open
Abstract
Genetic epilepsy with febrile seizures plus (GEFS+) is an autosomal dominant familial epilepsy syndrome characterized by distinctive phenotypic heterogeneity within families. The SCN1B c.363C>G (p.Cys121Trp) variant has been identified in independent, multi-generational families with GEFS+. Although the variant is present in population databases (at very low frequency), there is strong clinical, genetic, and functional evidence to support pathogenicity. Recurrent variants may be due to a founder event in which the variant has been inherited from a common ancestor. Here, we report evidence of a single founder event giving rise to the SCN1B c.363C>G variant in 14 independent families with epilepsy. A common haplotype was observed in all families, and the age of the most recent common ancestor was estimated to be approximately 800 years ago. Analysis of UK Biobank whole-exome-sequencing data identified 74 individuals with the same variant. All individuals carried haplotypes matching the epilepsy-affected families, suggesting all instances of the variant derive from a single mutational event. This unusual finding of a variant causing an autosomal dominant, early-onset disease in an outbred population that has persisted over many generations can be attributed to the relatively mild phenotype in most carriers and incomplete penetrance. Founder events are well established in autosomal recessive and late-onset disorders but are rarely observed in early-onset, autosomal dominant diseases. These findings suggest variants present in the population at low frequencies should be considered potentially pathogenic in mild phenotypes with incomplete penetrance and may be more important contributors to the genetic landscape than previously thought.
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Affiliation(s)
- Bronwyn E Grinton
- Epilepsy Research Centre, Department of Medicine, Austin Health, University of Melbourne, Heidelberg, VIC 3084, Australia
| | - Erandee Robertson
- Population Health and Immunity Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia; Department of Medical Biology, University of Melbourne, Parkville, VIC 3010, Australia
| | - Liam G Fearnley
- Population Health and Immunity Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia; Department of Medical Biology, University of Melbourne, Parkville, VIC 3010, Australia
| | - Ingrid E Scheffer
- Epilepsy Research Centre, Department of Medicine, Austin Health, University of Melbourne, Heidelberg, VIC 3084, Australia; Department of Paediatrics, The University of Melbourne, Royal Children's Hospital, Parkville, VIC 3052, Australia; Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, VIC 3052, Australia; Florey Institute of Neuroscience and Mental Health, Heidelberg, VIC 3084, Australia
| | - Anthony G Marson
- Department of Molecular and Clinical Pharmacology, University of Liverpool, Liverpool L69 3BX, UK
| | - Terence J O'Brien
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, VIC 3004, Australia; Department of Neurology, The Royal Melbourne Hospital, Parkville, VIC 3052, Australia; Department of Neurology, Alfred Health, Melbourne, VIC 3004, Australia; Department of Medicine, The University of Melbourne, Parkville, VIC 3010, Australia
| | - W Owen Pickrell
- Swansea University Medical School, Swansea University, Swansea SA2 8PP, UK; Department of Neurology, Morriston Hospital, Swansea Bay University Health Board, Swansea SA2 8PP, UK
| | - Mark I Rees
- Swansea University Medical School, Swansea University, Swansea SA2 8PP, UK; Faculty of Medicine & Health, University of Sydney, Camperdown, NSW 2006, Australia
| | - Sanjay M Sisodiya
- Chalfont Centre for Epilepsy, Chalfont St Peter, Buckinghamshire HP11 2FZ, UK; Department of Clinical and Experimental Epilepsy, UCL Queen Square Institute of Neurology, London WC1N 3BG, UK
| | - David J Balding
- Melbourne Integrative Genomics, School of BioSciences and School of Mathematics & Statistics, University of Melbourne, Parkville, VIC 3010, Australia
| | - Mark F Bennett
- Epilepsy Research Centre, Department of Medicine, Austin Health, University of Melbourne, Heidelberg, VIC 3084, Australia; Population Health and Immunity Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia; Department of Medical Biology, University of Melbourne, Parkville, VIC 3010, Australia
| | - Melanie Bahlo
- Population Health and Immunity Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia; Department of Medical Biology, University of Melbourne, Parkville, VIC 3010, Australia
| | - Samuel F Berkovic
- Epilepsy Research Centre, Department of Medicine, Austin Health, University of Melbourne, Heidelberg, VIC 3084, Australia.
| | - Karen L Oliver
- Epilepsy Research Centre, Department of Medicine, Austin Health, University of Melbourne, Heidelberg, VIC 3084, Australia; Population Health and Immunity Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia; Department of Medical Biology, University of Melbourne, Parkville, VIC 3010, Australia
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9
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Zhu Z, Bolt E, Newmaster K, Osei-Bonsu W, Cohen S, Cuddapah VA, Gupta S, Paudel S, Samanta D, Dang LT, Carney PR, Naik S. SCN1B Genetic Variants: A Review of the Spectrum of Clinical Phenotypes and a Report of Early Myoclonic Encephalopathy. CHILDREN (BASEL, SWITZERLAND) 2022; 9:children9101507. [PMID: 36291443 PMCID: PMC9600564 DOI: 10.3390/children9101507] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2022] [Revised: 09/26/2022] [Accepted: 09/30/2022] [Indexed: 11/06/2022]
Abstract
Background: Pathogenic variants in SCN1B, the gene encoding voltage-gated sodium channel b1/b1B subunits are associated with a spectrum of epileptic disorders. This study describes a child with early myoclonic encephalopathy and a compound heterozygous variant in the SCN1B gene (p.Arg85Cys and c.3G>C/p.Met1), along with the child’s clinical response to anti-seizure medications (ASMs) and the ketogenic diet. We reviewed the current clinical literature pertinent to SCN1B-related epilepsy. Methods: We described the evaluation and management of a patient with SCN1B-related developmental and epileptic encephalopathy (DEE). We used the Medline and Pubmed databases to review the various neurological manifestations associated with SCN1B genetic variants, and summarize the functional studies performed on SCN1B variants. Results: We identified 20 families and six individuals (including the index case described herein) reported to have SCN1B-related epilepsy. Individuals with monoallelic pathogenic variants in SCN1B often present with genetic epilepsy with febrile seizures plus (GEFS+), while those with biallelic pathogenic variants may present with developmental and epileptic encephalopathy (DEE). Individuals with DEE present with seizures of various semiologies (commonly myoclonic seizures) and status epilepticus at early infancy and are treated with various antiseizure medications. In our index case, adjunctive fenfluramine was started at 8 months of age at 0.2 mg/kg/day with gradual incremental increases to the final dose of 0.7 mg/kg/day over 5 weeks. Fenfluramine was effective in the treatment of seizures, resulting in a 50% reduction in myoclonic seizures, status epilepticus, and generalized tonic-clonic seizures, as well as a 70−90% reduction in focal seizures, with no significant adverse effects. Following the initiation of fenfluramine at eight months of age, there was also a 50% reduction in the rate of hospitalizations. Conclusions: SCN1B pathogenic variants cause epilepsy and neurodevelopmental impairment with variable expressivity and incomplete penetrance. The severity of disease is associated with the zygosity of the pathogenic variants. Biallelic variants in SCN1B can result in early myoclonic encephalopathy, and adjunctive treatment with fenfluramine may be an effective treatment for SCN1B-related DEE. Further research on the efficacy and safety of using newer ASMs, such as fenfluramine in patients under the age of 2 years is needed.
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Affiliation(s)
- Zahra Zhu
- College of Medicine, Penn State University, Hershey, PA 17033, USA
| | - Elizabeth Bolt
- College of Medicine, Penn State University, Hershey, PA 17033, USA
| | - Kyra Newmaster
- College of Medicine, Penn State University, Hershey, PA 17033, USA
| | - Wendy Osei-Bonsu
- College of Medicine, Penn State University, Hershey, PA 17033, USA
| | - Stacey Cohen
- Epilepsy Neurogenetics Initiative, Division of Neurology, Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Vishnu Anand Cuddapah
- Epilepsy Neurogenetics Initiative, Division of Neurology, Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Siddharth Gupta
- Kennedy Krieger Institute, Department of Neurology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Sita Paudel
- Department of Pediatrics and Neurology, Penn State Health Milton Hershey Medical Center, Hershey, PA 17033, USA
| | - Debopam Samanta
- Division of Pediatric Neurology, Arkansas Children’s Hospital, Little Rock, AR 72202, USA
| | - Louis T. Dang
- Department of Pediatrics, Division of Pediatric Neurology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Paul R. Carney
- Pediatric Neurology Division, University of Missouri Health Care, Columbia, MO 65212, USA
- Correspondence: (P.R.C.); (S.N.)
| | - Sunil Naik
- Department of Pediatrics and Neurology, Penn State Health Milton Hershey Medical Center, Hershey, PA 17033, USA
- Correspondence: (P.R.C.); (S.N.)
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10
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Mahdiannasser M, Rashidi-Nezhad A, Badv RS, Akrami SM. Exploring the genetic etiology of drug-resistant epilepsy: incorporation of exome sequencing into practice. Acta Neurol Belg 2022; 122:1457-1468. [PMID: 36127562 DOI: 10.1007/s13760-022-02095-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Accepted: 09/05/2022] [Indexed: 11/25/2022]
Abstract
BACKGROUND By affecting about 50 million people worldwide, epilepsy is considered a global concern in neurology. Intolerable enough, up to ¼ of all patients do not respond to antiepileptic drugs and have recurring seizures. Therefore, revealing the underlying etiology is quite demanding in a clinical context to improve diagnosis and disease management. METHODS Initially, 85 patients suspected of epilepsy underwent thorough clinical and paraclinical evaluation and 24 individuals with drug-resistant epilepsy entered the study. Using whole-exome sequencing, the genetic etiology of drug-resistant epilepsy was investigated and discerned whether this method could facilitate the management of drug-resistant epilepsy through personalized medicine. Eventually, functional annotation was performed and drug-gene interaction networks were constructed to find potential therapeutic targets. RESULTS We found eleven novel variants in various genes including IRF2BPL, ST3GAL3, and GPAA1, for which a few epilepsy-related variants are available in public databases. The overall diagnostic yield for likely pathogenic and pathogenic variants and the detection rate of novel variants were 25% and 84.6%, respectively. Based on the results, two patients were considered potential candidates for personalized medicine. The highest number of interaction with drugs was demonstrated for SCN1A, SCN2A, and GRIN2A genes. CONCLUSIONS This study highlighted the importance of consanguineous marriage in drug-resistant epilepsy and suggested the possibility of reduced penetrance and variable expressivity in some of the autosomal dominant cases. We also suggest that whole-exome sequencing could facilitate personalized management of drug-resistant epilepsy. Regarding drug-gene interactions, some genes such as SCN1A and SCN2A might serve as therapeutic targets in drug-resistant epilepsy.
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Affiliation(s)
- Mojdeh Mahdiannasser
- Department of Medical Genetics, School of Medicine, Tehran University of Medical Sciences, Poursina St., P.O. Box:14176-13151, Tehran, Iran
| | - Ali Rashidi-Nezhad
- Maternal, Fetal and Neonatal Research Center, Family Health Research Institute, Tehran University of Medical Sciences, Tehran, Iran.,Genetics Ward, Yas Hospital Complex, Tehran University of Medical Sciences, Tehran, Iran
| | - Reza Shervin Badv
- Children's Medical Center, Pediatrics Center of Excellence, Tehran University of Medical Sciences, Tehran, Iran
| | - Seyed Mohammad Akrami
- Department of Medical Genetics, School of Medicine, Tehran University of Medical Sciences, Poursina St., P.O. Box:14176-13151, Tehran, Iran.
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11
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Ramos-Mondragon R, Edokobi N, Hodges SL, Wang S, Bouza AA, Canugovi C, Scheuing C, Juratli L, Abel WR, Noujaim SF, Madamanchi NR, Runge MS, Lopez-Santiago LF, Isom LL. Neonatal Scn1b-null mice have sinoatrial node dysfunction, altered atrial structure, and atrial fibrillation. JCI Insight 2022; 7:152050. [PMID: 35603785 PMCID: PMC9220823 DOI: 10.1172/jci.insight.152050] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 04/12/2022] [Indexed: 11/17/2022] Open
Abstract
Loss-of-function (LOF) variants in SCN1B, encoding the voltage-gated sodium channel β1/β1B subunits, are linked to neurological and cardiovascular diseases. Scn1b-null mice have spontaneous seizures and ventricular arrhythmias and die by approximately 21 days after birth. β1/β1B Subunits play critical roles in regulating the excitability of ventricular cardiomyocytes and maintaining ventricular rhythmicity. However, whether they also regulate atrial excitability is unknown. We used neonatal Scn1b-null mice to model the effects of SCN1B LOF on atrial physiology in pediatric patients. Scn1b deletion resulted in altered expression of genes associated with atrial dysfunction. Scn1b-null hearts had a significant accumulation of atrial collagen, increased susceptibility to pacing induced atrial fibrillation (AF), sinoatrial node (SAN) dysfunction, and increased numbers of cholinergic neurons in ganglia that innervate the SAN. Atropine reduced the incidence of AF in null animals. Action potential duration was prolonged in null atrial myocytes, with increased late sodium current density and reduced L-type calcium current density. Scn1b LOF results in altered atrial structure and AF, demonstrating the critical role played by Scn1b in atrial physiology during early postnatal mouse development. Our results suggest that SCN1B LOF variants may significantly impact the developing pediatric heart.
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Affiliation(s)
| | | | | | | | | | - Chandrika Canugovi
- Department of Internal Medicine, Division of Cardiovascular Medicine, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | | | | | | | - Sami F. Noujaim
- Department of Molecular Pharmacology & Physiology, University of South Florida College of Medicine, Tampa, Florida, USA
| | - Nageswara R. Madamanchi
- Department of Internal Medicine, Division of Cardiovascular Medicine, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Marschall S. Runge
- Department of Internal Medicine, Division of Cardiovascular Medicine, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | | | - Lori L. Isom
- Department of Pharmacology and
- Department of Neurology and
- Department of Molecular & Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan, USA
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12
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Sahly AN, Shevell M, Sadleir LG, Myers KA. SUDEP risk and autonomic dysfunction in genetic epilepsies. Auton Neurosci 2021; 237:102907. [PMID: 34773737 DOI: 10.1016/j.autneu.2021.102907] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Revised: 10/11/2021] [Accepted: 11/06/2021] [Indexed: 01/02/2023]
Abstract
The underlying pathophysiology of sudden unexpected death in epilepsy (SUDEP) remains unclear. This phenomenon is likely multifactorial, and there is considerable evidence that genetic factors play a role. There are certain genetic causes of epilepsy in which the risk of SUDEP appears to be increased relative to epilepsy overall. For individuals with pathogenic variants in genes including SCN1A, SCN1B, SCN8A, SCN2A, GNB5, KCNA1 and DEPDC5, there are varying degrees of evidence to suggest an increased risk for sudden death. Why the risk for sudden death is higher is not completely clear; however, in many cases pathogenic variants in these genes are also associated with autonomic dysfunction, which is hypothesized as a contributing factor to SUDEP. We review the evidence for increased SUDEP risk for patients with epilepsy due to pathogenic variants in these genes, and also discuss what is known about autonomic dysfunction in these contexts.
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Affiliation(s)
- Ahmed N Sahly
- Division of Neurology, Department of Pediatrics, Montreal Children's Hospital, McGill University Health Centre, Montreal, Quebec, Canada; Department of Neurosciences, King Faisal Specialist Hospital & Research Centre, Jeddah, Saudi Arabia
| | - Michael Shevell
- Division of Neurology, Department of Pediatrics, Montreal Children's Hospital, McGill University Health Centre, Montreal, Quebec, Canada; Department of Neurology and Neurosurgery, Montreal Children's Hospital, McGill University Health Centre, Montreal, Quebec, Canada; Research Institute of the McGill University Medical Centre, Montreal, Quebec, Canada
| | - Lynette G Sadleir
- Department of Paediatrics and Child Health, University of Otago, Wellington, New Zealand
| | - Kenneth A Myers
- Division of Neurology, Department of Pediatrics, Montreal Children's Hospital, McGill University Health Centre, Montreal, Quebec, Canada; Department of Neurology and Neurosurgery, Montreal Children's Hospital, McGill University Health Centre, Montreal, Quebec, Canada; Research Institute of the McGill University Medical Centre, Montreal, Quebec, Canada.
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13
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New avenues in molecular genetics for the diagnosis and application of therapeutics to the epilepsies. Epilepsy Behav 2021; 121:106428. [PMID: 31400936 DOI: 10.1016/j.yebeh.2019.07.029] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/05/2019] [Revised: 06/14/2019] [Accepted: 07/06/2019] [Indexed: 11/22/2022]
Abstract
Genetic epidemiology studies have shown that most epilepsies involve some genetic cause. In addition, twin studies have helped strengthen the hypothesis that in most patients with epilepsy, a complex inheritance is involved. More recently, with the development of high-density single-nucleotide polymorphism (SNP) microarrays and next-generation sequencing (NGS) technologies, the discovery of genes related to the epilepsies has accelerated tremendously. Especially, the use of whole exome sequencing (WES) has had a considerable impact on the identification of rare genetic variants with large effect sizes, including inherited or de novo mutations in severe forms of childhood epilepsies. The identification of pathogenic variants in patients with these childhood epilepsies provides many benefits for patients and families, such as the confirmation of the genetic nature of the diseases. This process will allow for better genetic counseling, more accurate therapy decisions, and a significant positive emotional impact. However, to study the genetic component of the more common forms of epilepsy, the use of high-density SNP arrays in genome-wide association studies (GWAS) seems to be the strategy of choice. As such, researchers can identify loci containing genetic variants associated with the common forms of epilepsy. The knowledge generated over the past two decades about the effects of the mutations that cause the monogenic epilepsy is tremendous; however, the scientific community is just starting to apply this information in order to generate better target treatments.
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14
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Scala M, Efthymiou S, Sultan T, De Waele J, Panciroli M, Salpietro V, Maroofian R, Striano P, Van Petegem F, Houlden H, Bosmans F. Homozygous SCN1B variants causing early infantile epileptic encephalopathy 52 affect voltage-gated sodium channel function. Epilepsia 2021; 62:e82-e87. [PMID: 33901312 PMCID: PMC8585727 DOI: 10.1111/epi.16913] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 04/08/2021] [Accepted: 04/08/2021] [Indexed: 10/21/2022]
Abstract
We identified nine patients from four unrelated families harboring three biallelic variants in SCN1B (NM_001037.5: c.136C>T; p.[Arg46Cys], c.178C>T; p.[Arg60Cys], and c.472G>A; p.[Val158Met]). All subjects presented with early infantile epileptic encephalopathy 52 (EIEE52), a rare, severe developmental and epileptic encephalopathy featuring infantile onset refractory seizures followed by developmental stagnation or regression. Because SCN1B influences neuronal excitability through modulation of voltage-gated sodium (NaV ) channel function, we examined the effects of human SCN1BR46C (β1R46C ), SCN1BR60C (β1R60C ), and SCN1BV158M (β1V158M ) on the three predominant brain NaV channel subtypes NaV 1.1 (SCN1A), NaV 1.2 (SCN2A), and NaV 1.6 (SCN8A). We observed a shift toward more depolarizing potentials of conductance-voltage relationships (NaV 1.2/β1R46C , NaV 1.2/β1R60C , NaV 1.6/β1R46C , NaV 1.6/β1R60C , and NaV 1.6/β1V158M ) and channel availability (NaV 1.1/β1R46C , NaV 1.1/β1V158M , NaV 1.2/β1R46C , NaV 1.2/β1R60C , and NaV 1.6/β1V158M ), and detected a slower recovery from fast inactivation for NaV 1.1/β1V158M . Combined with modeling data indicating perturbation-induced structural changes in β1, these results suggest that the SCN1B variants reported here can disrupt normal NaV channel function in the brain, which may contribute to EIEE52.
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Affiliation(s)
- Marcello Scala
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, and Maternal and Child Health, University of Genoa, Genoa, Italy
- Department of Neuromuscular Disorders, Institute of Neurology, University College London, London, UK
| | - Stephanie Efthymiou
- Department of Neuromuscular Disorders, Institute of Neurology, University College London, London, UK
| | - Tipu Sultan
- Department of Pediatric Neurology, Children's Hospital and Institute of Child Health Lahore, Lahore, Pakistan
| | - Jolien De Waele
- Faculty of Medicine and Health Sciences, Department of Basic and Applied Medical Sciences, Ghent University, Ghent, Belgium
| | - Marta Panciroli
- Department of Neuromuscular Disorders, Institute of Neurology, University College London, London, UK
| | - Vincenzo Salpietro
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, and Maternal and Child Health, University of Genoa, Genoa, Italy
- Department of Neuromuscular Disorders, Institute of Neurology, University College London, London, UK
| | - Reza Maroofian
- Department of Neuromuscular Disorders, Institute of Neurology, University College London, London, UK
| | - Pasquale Striano
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, and Maternal and Child Health, University of Genoa, Genoa, Italy
- Pediatric Neurology and Muscular Diseases Unit, G. Gaslini Institute, Genoa, Italy
| | - Filip Van Petegem
- Department of Biochemistry and Molecular Biology, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Henry Houlden
- Department of Neuromuscular Disorders, Institute of Neurology, University College London, London, UK
| | - Frank Bosmans
- Faculty of Medicine and Health Sciences, Department of Basic and Applied Medical Sciences, Ghent University, Ghent, Belgium
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15
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Ademuwagun IA, Rotimi SO, Syrbe S, Ajamma YU, Adebiyi E. Voltage Gated Sodium Channel Genes in Epilepsy: Mutations, Functional Studies, and Treatment Dimensions. Front Neurol 2021; 12:600050. [PMID: 33841294 PMCID: PMC8024648 DOI: 10.3389/fneur.2021.600050] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Accepted: 03/01/2021] [Indexed: 12/19/2022] Open
Abstract
Genetic epilepsy occurs as a result of mutations in either a single gene or an interplay of different genes. These mutations have been detected in ion channel and non-ion channel genes. A noteworthy class of ion channel genes are the voltage gated sodium channels (VGSCs) that play key roles in the depolarization phase of action potentials in neurons. Of huge significance are SCN1A, SCN1B, SCN2A, SCN3A, and SCN8A genes that are highly expressed in the brain. Genomic studies have revealed inherited and de novo mutations in sodium channels that are linked to different forms of epilepsies. Due to the high frequency of sodium channel mutations in epilepsy, this review discusses the pathogenic mutations in the sodium channel genes that lead to epilepsy. In addition, it explores the functional studies on some known mutations and the clinical significance of VGSC mutations in the medical management of epilepsy. The understanding of these channel mutations may serve as a strong guide in making effective treatment decisions in patient management.
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Affiliation(s)
- Ibitayo Abigail Ademuwagun
- Covenant University Bioinformatics Research, Covenant University, Ota, Nigeria
- Department of Biochemistry, Covenant University, Ota, Nigeria
| | - Solomon Oladapo Rotimi
- Covenant University Bioinformatics Research, Covenant University, Ota, Nigeria
- Department of Biochemistry, Covenant University, Ota, Nigeria
| | - Steffen Syrbe
- Clinic for Pediatric and Adolescent Medicine, Heidelberg University, Heidelberg, Germany
| | | | - Ezekiel Adebiyi
- Covenant University Bioinformatics Research, Covenant University, Ota, Nigeria
- Department of Computer and Information Sciences, Covenant University, Ota, Nigeria
- Division of Applied Bioinformatics, German Cancer Research Center (DKFZ), Heidelberg, Germany
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16
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Hull JM, O’Malley HA, Chen C, Yuan Y, Denomme N, Bouza AA, Anumonwo C, Lopez‐Santiago LF, Isom LL. Excitatory and inhibitory neuron defects in a mouse model of Scn1b-linked EIEE52. Ann Clin Transl Neurol 2020; 7:2137-2149. [PMID: 32979291 PMCID: PMC7664274 DOI: 10.1002/acn3.51205] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Revised: 08/25/2020] [Accepted: 08/27/2020] [Indexed: 01/24/2023] Open
Abstract
OBJECTIVE Human variants in voltage-gated sodium channel (VGSC) α and β subunit genes are linked to developmental and epileptic encephalopathies (DEEs). Inherited, biallelic, loss-of-function variants in SCN1B, encoding the β1/β1B subunits, are linked to early infantile DEE (EIEE52). De novo, monoallelic variants in SCN1A (Nav1.1), SCN2A (Nav1.2), SCN3A (Nav1.3), and SCN8A (Nav1.6) are also linked to DEEs. While these VGSC-linked DEEs have similar presentations, they have diverse mechanisms of altered neuronal excitability. Mouse models have suggested that Scn2a-, Scn3a-, and Scn8a-linked DEE variants are, in general, gain of function, resulting in increased persistent or resurgent sodium current (INa ) and pyramidal neuron hyperexcitability. In contrast, Scn1a-linked DEE variants, in general, are loss-of-function, resulting in decreased INa and hypoexcitability of fast-spiking interneurons. VGSC β1 subunits associate with Nav1.1, Nav1.2, Nav1.3, and Nav1.6 and are expressed throughout the brain, raising the possibility that insults to both pyramidal and interneuron excitability may drive EIEE52 pathophysiology. METHODS We investigated excitability defects in pyramidal and parvalbumin-positive (PV +) interneurons in the Scn1b-/- model of EIEE52. We also used Scn1bFL/FL mice to delete Scn1b in specific neuronal populations. RESULTS Scn1b-/- cortical PV + interneurons were hypoexcitable, with reduced INa density. Scn1b-/- cortical pyramidal neurons had population-specific changes in excitability and impaired INa density. Scn1b deletion in PV + neurons resulted in 100% lethality, whereas deletion in Emx1 + or Camk2a + neurons did not affect survival. INTERPRETATION This work suggests that SCN1B-linked DEE variants impact both excitatory and inhibitory neurons, leading to the increased severity of EIEE52 relative to other DEEs.
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Affiliation(s)
- Jacob M. Hull
- Neuroscience Graduate ProgramUniversity of Michigan Medical SchoolAnn ArborMI48109USA
| | | | - Chunling Chen
- Department of PharmacologyUniversity of Michigan Medical SchoolAnn ArborMI48109USA
| | - Yukun Yuan
- Department of PharmacologyUniversity of Michigan Medical SchoolAnn ArborMI48109USA
| | - Nicholas Denomme
- Department of PharmacologyUniversity of Michigan Medical SchoolAnn ArborMI48109USA
| | - Alexandra A. Bouza
- Department of PharmacologyUniversity of Michigan Medical SchoolAnn ArborMI48109USA
| | - Charles Anumonwo
- Department of PharmacologyUniversity of Michigan Medical SchoolAnn ArborMI48109USA
| | | | - Lori L. Isom
- Neuroscience Graduate ProgramUniversity of Michigan Medical SchoolAnn ArborMI48109USA
- Department of PharmacologyUniversity of Michigan Medical SchoolAnn ArborMI48109USA
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17
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Chow CY, Absalom N, Biggs K, King GF, Ma L. Venom-derived modulators of epilepsy-related ion channels. Biochem Pharmacol 2020; 181:114043. [PMID: 32445870 DOI: 10.1016/j.bcp.2020.114043] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Accepted: 05/18/2020] [Indexed: 12/18/2022]
Abstract
Epilepsy is characterised by spontaneous recurrent seizures that are caused by an imbalance between neuronal excitability and inhibition. Since ion channels play fundamental roles in the generation and propagation of action potentials as well as neurotransmitter release at a subset of excitatory and inhibitory synapses, their dysfunction has been linked to a wide variety of epilepsies. Indeed, these unique proteins are the major biological targets for antiepileptic drugs. Selective targeting of a specific ion channel subtype remains challenging for small molecules, due to the high level of homology among members of the same channel family. As a consequence, there is a growing trend to target ion channels with biologics. Venoms are the best known natural source of ion channel modulators, and venom peptides are increasingly recognised as potential therapeutics due to their high selectivity and potency gained through millions of years of evolutionary selection pressure. Here we describe the major ion channel families involved in the pathogenesis of various types of epilepsy, including voltage-gated Na+, K+, Ca2+ channels, Cys-loop receptors, ionotropic glutamate receptors and P2X receptors, and currently available venom-derived peptides that target these channel proteins. Although only a small number of venom peptides have successfully progressed to the clinic, there is reason to be optimistic about their development as antiepileptic drugs, notwithstanding the challenges associated with development of any class of peptide drug.
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Affiliation(s)
- Chun Yuen Chow
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Nathan Absalom
- Brain and Mind Centre, School of Pharmacy, Faculty of Health and Medicine, The University of Sydney, Sydney, NSW 2050, Australia
| | - Kimberley Biggs
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Glenn F King
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia.
| | - Linlin Ma
- Griffith Institute for Drug Discovery, Griffith University, Nathan, QLD 4111, Australia.
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18
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Mei D, Cetica V, Marini C, Guerrini R. Dravet syndrome as part of the clinical and genetic spectrum of sodium channel epilepsies and encephalopathies. Epilepsia 2020; 60 Suppl 3:S2-S7. [PMID: 31904125 DOI: 10.1111/epi.16054] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Revised: 05/06/2019] [Accepted: 05/08/2019] [Indexed: 01/01/2023]
Abstract
Dravet syndrome is the most studied form of genetic epilepsy. It has now been clarified that the clinical spectrum of the syndrome does not have firmly established boundaries. The core phenotype is characterized by intractable, mainly clonic, seizures precipitated by increased body temperature with onset in the first year of life and subsequent appearance of multiple seizures types still precipitated by, but not confined to, hyperthermia. Cognitive impairment is invariably present when the full syndrome is manifested. This complex of symptoms is related to mutations in the SCN1A gene, which are often de novo and constitutional but can also be inherited from a parent with less severe clinical manifestations or be present as somatic mosaicism. Inheritance from less severely affected individuals, at times only having experienced a few febrile seizures, and differences in severity, even within the same family, with a subset of patients only showing fragments of the syndrome, testify to a remarkable phenotypic heterogeneity as far as severity, but less so clinical phenomenology, are concerned. This characteristic, together with underascertainment of SCN1A mutations due to human errors or technical limitations in uncovering alternative pathogenic molecular mechanisms, such as genomic rearrangements or poison exons, has contributed to making clinicians and geneticists suspicious that Dravet syndrome may be caused by more than one gene. This opinion has been further amplified by the description of other genetic disorders, such as PCDH19- or CHD2-related epilepsy, whose phenotypes have included fragments of the Dravet phenotypic spectrum, and by the suboptimal characterization of phenotypes associated with mutations in SCN1B, HCN1, KCN2A, GABRA1, GABRG2, and STXBP1. The SCN1A gene-Dravet syndrome association is in our opinion highly specific. However, because the syndrome spectrum is wide, fragments of it can at times also be manifested in other genetic epilepsy syndromes, thereby leading to overdiagnosis of Dravet syndrome beyond SCN1A. Dravet syndrome is in turn a severe SCN1A phenotype within a continuum of SCN1A-related clinical phenomenology.
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Affiliation(s)
- Davide Mei
- Pediatric Neurology, Neurogenetics, and Neurobiology Unit and Laboratories, Meyer Children's Hospital-University of Florence, Florence, Italy
| | - Valentina Cetica
- Pediatric Neurology, Neurogenetics, and Neurobiology Unit and Laboratories, Meyer Children's Hospital-University of Florence, Florence, Italy
| | - Carla Marini
- Pediatric Neurology, Neurogenetics, and Neurobiology Unit and Laboratories, Meyer Children's Hospital-University of Florence, Florence, Italy
| | - Renzo Guerrini
- Pediatric Neurology, Neurogenetics, and Neurobiology Unit and Laboratories, Meyer Children's Hospital-University of Florence, Florence, Italy.,IRCCS Stella Maris Foundation, Pisa, Italy
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19
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Abstract
Developmental and epileptic encephalopathies (DEEs) can be primarily attributed to genetic causes. The genetic landscape of DEEs has been largely shaped by the rise of high-throughput sequencing, which led to the discovery of new DEE-associated genes and helped identify de novo pathogenic variants. We discuss briefly the contribution of de novo variants to DEE and also focus on alternative inheritance models that contribute to DEE. First, autosomal recessive inheritance in outbred populations may have a larger contribution than previously appreciated, accounting for up to 13% of DEEs. A small subset of genes that typically harbor de novo variants have been associated with recessive inheritance, and often these individuals have more severe clinical presentations. Additionally, pathogenic variants in X-linked genes have been identified in both affected males and females, possibly due to a lack of X-chromosome inactivation skewing. Collectively, exome sequencing has resulted in a molecular diagnosis for many individuals with DEE, but this still leaves many cases unsolved. Multiple factors contribute to the missing etiology, including nonexonic variants, mosaicism, epigenetics, and oligogenic inheritance. Here, we focus on the first 2 factors. We discuss the promises and challenges of genome sequencing, which allows for a more comprehensive analysis of the genome, including interpretation of structural and noncoding variants and also yields a high number of de novo variants for interpretation. We also consider the contribution of genetic mosaicism, both what it means for a molecular diagnosis in mosaic individuals and the important implications for genetic counseling.
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Affiliation(s)
- Hannah C Happ
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Gemma L Carvill
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
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20
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Matthews E, Balestrini S, Sisodiya SM, Hanna MG. Muscle and brain sodium channelopathies: genetic causes, clinical phenotypes, and management approaches. THE LANCET CHILD & ADOLESCENT HEALTH 2020; 4:536-547. [PMID: 32142633 DOI: 10.1016/s2352-4642(19)30425-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Revised: 10/29/2019] [Accepted: 12/12/2019] [Indexed: 01/26/2023]
Abstract
Voltage-gated sodium channels are essential for excitability of skeletal muscle fibres and neurons. An increasing number of disabling or fatal paediatric neurological disorders linked to mutations of voltage-gated sodium channel genes are recognised. Muscle phenotypes include episodic paralysis, myotonia, neonatal hypotonia, respiratory compromise, laryngospasm or stridor, congenital myasthenia, and myopathy. Evidence suggests a possible link between sodium channel dysfunction and sudden infant death. Increasingly recognised phenotypes of brain sodium channelopathies include several epilepsy disorders and complex encephalopathies. Together, these early-onset muscle and brain phenotypes have a substantial morbidity and a considerable mortality. Important advances in understanding the pathophysiological mechanisms underlying these channelopathies have helped to identify effective targeted therapies. The availability of effective treatments underlines the importance of increasing clinical awareness and the need to achieve a precise genetic diagnosis. In this Review, we describe the expanded range of phenotypes of muscle and brain sodium channelopathies and the underlying knowledge regarding mechanisms of sodium channel dysfunction. We also outline a diagnostic approach and review the available treatment options.
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Affiliation(s)
- Emma Matthews
- Department of Neuromuscular Diseases, Medical Research Council Centre for Neuromuscular Diseases, University College London Queen Square Institute of Neurology, London, UK; National Hospital for Neurology and Neurosurgery, University College London Hospitals National Health Service Foundation Trust, London, UK.
| | - Simona Balestrini
- Department of Clinical and Experimental Epilepsy, University College London Queen Square Institute of Neurology, London, UK; Chalfont Centre for Epilepsy, Buckinghamshire, UK; National Hospital for Neurology and Neurosurgery, University College London Hospitals National Health Service Foundation Trust, London, UK
| | - Sanjay M Sisodiya
- Department of Clinical and Experimental Epilepsy, University College London Queen Square Institute of Neurology, London, UK; Chalfont Centre for Epilepsy, Buckinghamshire, UK; National Hospital for Neurology and Neurosurgery, University College London Hospitals National Health Service Foundation Trust, London, UK
| | - Michael G Hanna
- Department of Neuromuscular Diseases, Medical Research Council Centre for Neuromuscular Diseases, University College London Queen Square Institute of Neurology, London, UK; National Hospital for Neurology and Neurosurgery, University College London Hospitals National Health Service Foundation Trust, London, UK
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21
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Aeby A, Sculier C, Bouza AA, Askar B, Lederer D, Schoonjans A, Vander Ghinst M, Ceulemans B, Offord J, Lopez‐Santiago LF, Isom LL. SCN1B-linked early infantile developmental and epileptic encephalopathy. Ann Clin Transl Neurol 2019; 6:2354-2367. [PMID: 31709768 PMCID: PMC6917350 DOI: 10.1002/acn3.50921] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 09/22/2019] [Accepted: 09/23/2019] [Indexed: 01/12/2023] Open
Abstract
OBJECTIVE Patients with Early Infantile Epileptic Encephalopathy (EIEE) 52 have inherited, homozygous variants in the gene SCN1B, encoding the voltage-gated sodium channel (VGSC) β1 and β1B non-pore-forming subunits. METHODS Here, we describe the detailed electroclinical features of a biallelic SCN1B patient with a previously unreported variant, p.Arg85Cys. RESULTS The female proband showed hypotonia from birth, multifocal myoclonus at 2.5 months, then focal seizures and myoclonic status epilepticus (SE) at 3 months, triggered by fever. Auditory brainstem response (ABR) showed bilateral hearing loss. Epilepsy was refractory and the patient had virtually no development. Administration of fenfluramine resulted in a significant reduction in seizure frequency and resolution of SE episodes that persisted after a 2-year follow-up. The patient phenotype is more compatible with early infantile developmental and epileptic encephalopathy (DEE) than with typical Dravet syndrome (DS), as previously diagnosed for other patients with homozygous SCN1B variants. Biochemical and electrophysiological analyses of the SCN1B variant expressed in heterologous cells showed cell surface expression of the mutant β1 subunit, similar to wild-type (WT), but with loss of normal β1-mediated modification of human Nav 1.1-generated sodium current, suggesting that SCN1B-p.Arg85Cys is a loss-of-function (LOF) variant. INTERPRETATION Importantly, a review of the literature in light of our results suggests that the term, early infantile developmental and epileptic encephalopathy, is more appropriate than either EIEE or DS to describe biallelic SCN1B patients.
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Affiliation(s)
- Alec Aeby
- Pediatric NeurologyQueen Fabiola Children HospitalULBBrusselsBelgium
| | | | - Alexandra A. Bouza
- Department of PharmacologyUniversity of Michigan Medical SchoolAnn ArborMI48109
| | - Brandon Askar
- Department of PharmacologyUniversity of Michigan Medical SchoolAnn ArborMI48109
| | | | | | - Marc Vander Ghinst
- ENT DepartmentULB‐Hôpital ErasmeUniversité libre de Bruxelles (ULB)BrusselsBelgium
- Laboratoire de Cartographie fonctionnelle du CerveauUNI – ULB Neuroscience InstituteUniversité libre de Bruxelles (ULB)BrusselsBelgium
| | | | - James Offord
- Department of PharmacologyUniversity of Michigan Medical SchoolAnn ArborMI48109
| | | | - Lori L. Isom
- Department of PharmacologyUniversity of Michigan Medical SchoolAnn ArborMI48109
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22
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Darras N, Ha TK, Rego S, Martin P, Barroso E, Slavotinek AM, Cilio MR. Developmental and epileptic encephalopathy in two siblings with a novel, homozygous missense variant in
SCN1B. Am J Med Genet A 2019; 179:2190-2195. [DOI: 10.1002/ajmg.a.61344] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Revised: 08/08/2019] [Accepted: 08/09/2019] [Indexed: 11/07/2022]
Affiliation(s)
- Natasha Darras
- Department of PathologyUniversity of California San Francisco San Francisco California
| | - Thoa K. Ha
- Division of Medical Genetics, Department of PediatricsUniversity of California San Francisco San Francisco California
| | - Shannon Rego
- Division of Medical Genetics, Department of PediatricsUniversity of California San Francisco San Francisco California
| | - Pierre‐Marie Martin
- Institute for Human Genetics, University of California San Francisco San Francisco California
| | - Eva Barroso
- Department of Molecular Genetics, Instituto de Genética Médica y Molecular (INGEMM), IdiPAZ, Hospital Universitario la Paz, Universidad Autónoma de Madrid (UAM) Madrid Spain
| | - Anne M. Slavotinek
- Division of Medical Genetics, Department of PediatricsUniversity of California San Francisco San Francisco California
| | - Maria R. Cilio
- Institute for Human Genetics, University of California San Francisco San Francisco California
- Division of Pediatric Epilepsy, Department of NeurologyUniversity of California San Francisco California USA
- Division of Pediatric Neurology, Department of PediatricsUniversity of Louvain Brussels Belgium
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23
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O'Malley HA, Hull JM, Clawson BC, Chen C, Owens-Fiestan G, Jameson MB, Aton SJ, Parent JM, Isom LL. Scn1b deletion in adult mice results in seizures and SUDEP. Ann Clin Transl Neurol 2019; 6:1121-1126. [PMID: 31211177 PMCID: PMC6562025 DOI: 10.1002/acn3.785] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Revised: 04/05/2019] [Accepted: 04/08/2019] [Indexed: 01/01/2023] Open
Abstract
Pathogenic loss‐of‐function variants in SCN1B are linked to Dravet syndrome (DS). Previous work suggested that neuronal pathfinding defects underlie epileptogenesis and SUDEP in the Scn1b null mouse model of DS. We tested this hypothesis by inducing Scn1b deletion in adult mice that had developed normally. Epilepsy and SUDEP, which occur by postnatal day 21 in Scn1b null animals, were observed within 20 days of induced Scn1b deletion in adult mice, suggesting that epileptogenesis in SCN1B‐DS does not result from defective brain development. Thus, the developmental brain defects observed previously in Scn1b null mice may model other co‐morbidities of DS.
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Affiliation(s)
- Heather A O'Malley
- Department of Pharmacology University of Michigan Ann Arbor Michigan 48109
| | - Jacob M Hull
- Neuroscience Graduate Program University of Michigan Ann Arbor Michigan 48109
| | - Brittany C Clawson
- Department of Molecular, Cellular, and Developmental Biology University of Michigan Ann Arbor Michigan 48109
| | - Chunling Chen
- Department of Pharmacology University of Michigan Ann Arbor Michigan 48109
| | - Gic Owens-Fiestan
- Department of Neurology University of Michigan Ann Arbor Michigan 48109
| | - Margaret B Jameson
- Department of Neurology University of Michigan Ann Arbor Michigan 48109.,Present address: Department of Neuroscience University of Wisconsin Madison Wisconsin
| | - Sara J Aton
- Neuroscience Graduate Program University of Michigan Ann Arbor Michigan 48109.,Department of Molecular, Cellular, and Developmental Biology University of Michigan Ann Arbor Michigan 48109
| | - Jack M Parent
- Neuroscience Graduate Program University of Michigan Ann Arbor Michigan 48109.,Department of Neurology University of Michigan Ann Arbor Michigan 48109
| | - Lori L Isom
- Department of Pharmacology University of Michigan Ann Arbor Michigan 48109.,Neuroscience Graduate Program University of Michigan Ann Arbor Michigan 48109.,Department of Neurology University of Michigan Ann Arbor Michigan 48109
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24
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Yuan Y, O'Malley HA, Smaldino MA, Bouza AA, Hull JM, Isom LL. Delayed maturation of GABAergic signaling in the Scn1a and Scn1b mouse models of Dravet Syndrome. Sci Rep 2019; 9:6210. [PMID: 30996233 PMCID: PMC6470170 DOI: 10.1038/s41598-019-42191-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Accepted: 03/25/2019] [Indexed: 01/25/2023] Open
Abstract
Dravet syndrome (DS) is a catastrophic developmental and epileptic encephalopathy characterized by severe, pharmacoresistant seizures and the highest risk of Sudden Unexpected Death in Epilepsy (SUDEP) of all epilepsy syndromes. Here, we investigated the time course of maturation of neuronal GABAergic signaling in the Scn1b-/- and Scn1a+/- mouse models of DS. We found that GABAergic signaling remains immature in both DS models, with a depolarized reversal potential for GABAA-evoked currents compared to wildtype in the third postnatal week. Treatment of Scn1b-/- mice with bumetanide resulted in a delay in SUDEP onset compared to controls in a subset of mice, without prevention of seizure activity or amelioration of failure to thrive. We propose that delayed maturation of GABAergic signaling may contribute to epileptogenesis in SCN1B- and SCN1A-linked DS. Thus, targeting the polarity of GABAergic signaling in brain may be an effective therapeutic strategy to reduce SUDEP risk in DS.
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Affiliation(s)
- Yukun Yuan
- Department of Pharmacology, University of Michigan, Ann Arbor, MI, 48109-5632, USA
| | - Heather A O'Malley
- Department of Pharmacology, University of Michigan, Ann Arbor, MI, 48109-5632, USA
| | - Melissa A Smaldino
- Department of Pharmacology, University of Michigan, Ann Arbor, MI, 48109-5632, USA
- Department of Biology, Ball State University, Muncie, IN, 47306, USA
| | - Alexandra A Bouza
- Department of Pharmacology, University of Michigan, Ann Arbor, MI, 48109-5632, USA
| | - Jacob M Hull
- Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI, 48109-2215, USA
| | - Lori L Isom
- Department of Pharmacology, University of Michigan, Ann Arbor, MI, 48109-5632, USA.
- Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI, 48109-2215, USA.
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25
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Calhoun JD, Carvill GL. Unravelling the genetic architecture of autosomal recessive epilepsy in the genomic era. J Neurogenet 2018; 32:295-312. [PMID: 30247086 DOI: 10.1080/01677063.2018.1513509] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The technological advancement of next-generation sequencing has greatly accelerated the pace of variant discovery in epilepsy. Despite an initial focus on autosomal dominant epilepsy due to the tractable nature of variant discovery with trios under a de novo model, more and more variants are being reported in families with epilepsies consistent with autosomal recessive (AR) inheritance. In this review, we touch on the classical AR epilepsy variants such as the inborn errors of metabolism and malformations of cortical development. However, we also highlight recently reported genes that are being identified by next-generation sequencing approaches and online 'matchmaking' platforms. Syndromes mainly characterized by seizures and complex neurodevelopmental disorders comorbid with epilepsy are discussed as an example of the wide phenotypic spectrum associated with the AR epilepsies. We conclude with a foray into the future, from the application of whole-genome sequencing to identify elusive epilepsy variants, to the promise of precision medicine initiatives to provide novel targeted therapeutics specific to the individual based on their clinical genetic testing.
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Affiliation(s)
- Jeffrey D Calhoun
- a Department of Neurology , Northwestern University Feinberg School of Medicine , Chicago , IL , USA
| | - Gemma L Carvill
- a Department of Neurology , Northwestern University Feinberg School of Medicine , Chicago , IL , USA
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26
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Chen C, Holth JK, Bunton-Stasyshyn R, Anumonwo CK, Meisler MH, Noebels JL, Isom LL. Mapt deletion fails to rescue premature lethality in two models of sodium channel epilepsy. Ann Clin Transl Neurol 2018; 5:982-987. [PMID: 30128323 PMCID: PMC6093838 DOI: 10.1002/acn3.599] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Accepted: 06/04/2018] [Indexed: 12/18/2022] Open
Abstract
Deletion of Mapt, encoding the microtubule‐binding protein Tau, prevents disease in multiple genetic models of hyperexcitability. To investigate whether the effect of Tau depletion is generalizable across multiple sodium channel gene‐linked models of epilepsy, we examined the Scn1b−/− mouse model of Dravet syndrome, and the Scn8aN1768D/+ model of Early Infantile Epileptic Encephalopathy. Both models display severe seizures and early mortality. We found no prolongation of survival between Scn1b−/−,Mapt+/+, Scn1b−/−,Mapt+/−, or Scn1b−/−,Mapt−/− mice or between Scn8aN1768D/+,Mapt+/+, Scn8aN1768D/+,Mapt+/−, or Scn8aN1768D/+,Mapt−/− mice. Thus, the effect of Mapt deletion on mortality in epileptic encephalopathy models is gene specific and provides further mechanistic insight.
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Affiliation(s)
- Chunling Chen
- Department of Pharmacology University of Michigan Medical School Ann Arbor Michigan 48109
| | - Jerrah K Holth
- Department of Neurology Baylor College of Medicine Houston Texas 77030.,Department of Molecular and Human Genetics Baylor College of Medicine Houston Texas 77030.,Present address: Department of Neurology Washington University St. Louis Missouri 63110
| | - Rosie Bunton-Stasyshyn
- Department of Human Genetics University of Michigan Medical School Ann Arbor Michigan 48109
| | - Charles K Anumonwo
- Department of Pharmacology University of Michigan Medical School Ann Arbor Michigan 48109
| | - Miriam H Meisler
- Department of Human Genetics University of Michigan Medical School Ann Arbor Michigan 48109
| | - Jeffrey L Noebels
- Department of Neurology Baylor College of Medicine Houston Texas 77030.,Department of Molecular and Human Genetics Baylor College of Medicine Houston Texas 77030
| | - Lori L Isom
- Department of Pharmacology University of Michigan Medical School Ann Arbor Michigan 48109
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27
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Winquist RJ, Cohen CJ. Integration of biological/pathophysiological contexts to help clarify genotype-phenotype mismatches in monogenetic diseases. Childhood epilepsies associated with SCN2A as a case study. Biochem Pharmacol 2018; 151:252-262. [DOI: 10.1016/j.bcp.2018.01.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Accepted: 01/02/2018] [Indexed: 12/30/2022]
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28
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Edokobi N, Isom LL. Voltage-Gated Sodium Channel β1/β1B Subunits Regulate Cardiac Physiology and Pathophysiology. Front Physiol 2018; 9:351. [PMID: 29740331 PMCID: PMC5924814 DOI: 10.3389/fphys.2018.00351] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Accepted: 03/20/2018] [Indexed: 12/19/2022] Open
Abstract
Cardiac myocyte contraction is initiated by a set of intricately orchestrated electrical impulses, collectively known as action potentials (APs). Voltage-gated sodium channels (NaVs) are responsible for the upstroke and propagation of APs in excitable cells, including cardiomyocytes. NaVs consist of a single, pore-forming α subunit and two different β subunits. The β subunits are multifunctional cell adhesion molecules and channel modulators that have cell type and subcellular domain specific functional effects. Variants in SCN1B, the gene encoding the Nav-β1 and -β1B subunits, are linked to atrial and ventricular arrhythmias, e.g., Brugada syndrome, as well as to the early infantile epileptic encephalopathy Dravet syndrome, all of which put patients at risk for sudden death. Evidence over the past two decades has demonstrated that Nav-β1/β1B subunits play critical roles in cardiac myocyte physiology, in which they regulate tetrodotoxin-resistant and -sensitive sodium currents, potassium currents, and calcium handling, and that Nav-β1/β1B subunit dysfunction generates substrates for arrhythmias. This review will highlight the role of Nav-β1/β1B subunits in cardiac physiology and pathophysiology.
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Affiliation(s)
| | - Lori L. Isom
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI, United States
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29
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Abstract
Fever-associated seizures or epilepsy (FASE) is primarily characterised by the occurrence of a seizure or epilepsy usually accompanied by a fever. It is common in infants and children, and generally includes febrile seizures (FS), febrile seizures plus (FS+), Dravet syndrome (DS) and genetic epilepsy with febrile seizures plus (GEFSP). The aetiology of FASE is unclear. Genetic factors may play crucial roles in FASE. Mutations in certain genes may cause a wide spectrum of phenotypical overlap ranging from isolated FS, FS+ and GEFSP to DS. Synapse-associated proteins, postsynaptic GABAA receptor, and sodium channels play important roles in synaptic transmission. Mutations in these genes may involve in the pathogenesis of FASE. Elevated temperature promotes synaptic vesicle (SV) recycling and enlarges SV size, which may enhance synaptic transmission and contribute to FASE occurring. This review provides an overview of the loci, genes, underlying pathogenesis and the fever-inducing effect of FASE. It may provide a more comprehensive understanding of pathogenesis and contribute to the clinical diagnosis of FASE.
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30
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Oyrer J, Maljevic S, Scheffer IE, Berkovic SF, Petrou S, Reid CA. Ion Channels in Genetic Epilepsy: From Genes and Mechanisms to Disease-Targeted Therapies. Pharmacol Rev 2018; 70:142-173. [PMID: 29263209 DOI: 10.1124/pr.117.014456] [Citation(s) in RCA: 163] [Impact Index Per Article: 27.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Accepted: 10/02/2017] [Indexed: 12/19/2022] Open
Abstract
Epilepsy is a common and serious neurologic disease with a strong genetic component. Genetic studies have identified an increasing collection of disease-causing genes. The impact of these genetic discoveries is wide reaching-from precise diagnosis and classification of syndromes to the discovery and validation of new drug targets and the development of disease-targeted therapeutic strategies. About 25% of genes identified in epilepsy encode ion channels. Much of our understanding of disease mechanisms comes from work focused on this class of protein. In this study, we review the genetic, molecular, and physiologic evidence supporting the pathogenic role of a number of different voltage- and ligand-activated ion channels in genetic epilepsy. We also review proposed disease mechanisms for each ion channel and highlight targeted therapeutic strategies.
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Affiliation(s)
- Julia Oyrer
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Melbourne, Australia (J.O., S.M., I.E.S., S.P., C.A.R.); Department of Medicine, Austin Health, University of Melbourne, Heidelberg West, Melbourne, Australia (I.E.S., S.F.B.); and Department of Paediatrics, University of Melbourne, Royal Children's Hospital, Melbourne, Australia (I.E.S.)
| | - Snezana Maljevic
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Melbourne, Australia (J.O., S.M., I.E.S., S.P., C.A.R.); Department of Medicine, Austin Health, University of Melbourne, Heidelberg West, Melbourne, Australia (I.E.S., S.F.B.); and Department of Paediatrics, University of Melbourne, Royal Children's Hospital, Melbourne, Australia (I.E.S.)
| | - Ingrid E Scheffer
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Melbourne, Australia (J.O., S.M., I.E.S., S.P., C.A.R.); Department of Medicine, Austin Health, University of Melbourne, Heidelberg West, Melbourne, Australia (I.E.S., S.F.B.); and Department of Paediatrics, University of Melbourne, Royal Children's Hospital, Melbourne, Australia (I.E.S.)
| | - Samuel F Berkovic
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Melbourne, Australia (J.O., S.M., I.E.S., S.P., C.A.R.); Department of Medicine, Austin Health, University of Melbourne, Heidelberg West, Melbourne, Australia (I.E.S., S.F.B.); and Department of Paediatrics, University of Melbourne, Royal Children's Hospital, Melbourne, Australia (I.E.S.)
| | - Steven Petrou
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Melbourne, Australia (J.O., S.M., I.E.S., S.P., C.A.R.); Department of Medicine, Austin Health, University of Melbourne, Heidelberg West, Melbourne, Australia (I.E.S., S.F.B.); and Department of Paediatrics, University of Melbourne, Royal Children's Hospital, Melbourne, Australia (I.E.S.)
| | - Christopher A Reid
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Melbourne, Australia (J.O., S.M., I.E.S., S.P., C.A.R.); Department of Medicine, Austin Health, University of Melbourne, Heidelberg West, Melbourne, Australia (I.E.S., S.F.B.); and Department of Paediatrics, University of Melbourne, Royal Children's Hospital, Melbourne, Australia (I.E.S.)
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31
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Hull JM, Isom LL. Voltage-gated sodium channel β subunits: The power outside the pore in brain development and disease. Neuropharmacology 2017; 132:43-57. [PMID: 28927993 DOI: 10.1016/j.neuropharm.2017.09.018] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Revised: 07/19/2017] [Accepted: 09/11/2017] [Indexed: 12/19/2022]
Abstract
Voltage gated sodium channels (VGSCs) were first identified in terms of their role in the upstroke of the action potential. The underlying proteins were later identified as saxitoxin and scorpion toxin receptors consisting of α and β subunits. We now know that VGSCs are heterotrimeric complexes consisting of a single pore forming α subunit joined by two β subunits; a noncovalently linked β1 or β3 and a covalently linked β2 or β4 subunit. VGSC α subunits contain all the machinery necessary for channel cell surface expression, ion conduction, voltage sensing, gating, and inactivation, in one central, polytopic, transmembrane protein. VGSC β subunits are more than simple accessories to α subunits. In the more than two decades since the original cloning of β1, our knowledge of their roles in physiology and pathophysiology has expanded immensely. VGSC β subunits are multifunctional. They confer unique gating mechanisms, regulate cellular excitability, affect brain development, confer distinct channel pharmacology, and have functions that are independent of the α subunits. The vast array of functions of these proteins stems from their special station in the channelome: being the only known constituents that are cell adhesion and intra/extracellular signaling molecules in addition to being part of channel complexes. This functional trifecta and how it goes awry demonstrates the power outside the pore in ion channel signaling complexes, broadening the term channelopathy beyond defects in ion conduction. This article is part of the Special Issue entitled 'Channelopathies.'
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Affiliation(s)
- Jacob M Hull
- Neuroscience Program and Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI 48109, United States
| | - Lori L Isom
- Neuroscience Program and Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI 48109, United States.
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Maljevic S, Reid CA, Petrou S. Models for discovery of targeted therapy in genetic epileptic encephalopathies. J Neurochem 2017; 143:30-48. [PMID: 28742937 DOI: 10.1111/jnc.14134] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Revised: 07/14/2017] [Accepted: 07/19/2017] [Indexed: 12/20/2022]
Abstract
Epileptic encephalopathies are severe disorders emerging in the first days to years of life that commonly include refractory seizures, various types of movement disorders, and different levels of developmental delay. In recent years, many de novo occurring variants have been identified in individuals with these devastating disorders. To unravel disease mechanisms, the functional impact of detected variants associated with epileptic encephalopathies is investigated in a range of cellular and animal models. This review addresses efforts to advance and use such models to identify specific molecular and cellular targets for the development of novel therapies. We focus on ion channels as the best-studied group of epilepsy genes. Given the clinical and genetic heterogeneity of epileptic encephalopathy disorders, experimental models that can reflect this complexity are critical for the development of disease mechanisms-based targeted therapy. The convergence of technological advances in gene sequencing, stem cell biology, genome editing, and high throughput functional screening together with massive unmet clinical needs provides unprecedented opportunities and imperatives for precision medicine in epileptic encephalopathies.
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Affiliation(s)
- Snezana Maljevic
- The Florey Institute of Neuroscience and Mental Health, Melbourne, Australia
| | - Christopher A Reid
- The Florey Institute of Neuroscience and Mental Health, Melbourne, Australia
| | - Steven Petrou
- The Florey Institute of Neuroscience and Mental Health, Melbourne, Australia.,University of Melbourne, Melbourne, Australia
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