1
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Wang S, Xie Z, Jun T, Ma X, Zhang M, Rao F, Xu H, Lu J, Ding X, Li Z. Identification of potential crucial genes and therapeutic targets for epilepsy. Eur J Med Res 2024; 29:43. [PMID: 38212777 PMCID: PMC10782668 DOI: 10.1186/s40001-024-01643-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Accepted: 01/04/2024] [Indexed: 01/13/2024] Open
Abstract
BACKGROUND Epilepsy, a central neurological disorder, has a complex genetic architecture. There is some evidence suggesting that genetic factors play a role in both the occurrence of epilepsy and its treatment. However, the genetic determinants of epilepsy are largely unknown. This study aimed to identify potential therapeutic targets for epilepsy. METHODS Differentially expressed genes (DEGs) were extracted from the expression profiles of GSE44031 and GSE1834. Gene co-expression analysis was used to confirm the regulatory relationship between newly discovered epilepsy candidate genes and known epilepsy genes. Expression quantitative trait loci analysis was conducted to determine if epilepsy risk single-nucleotide polymorphisms regulate DEGs' expression in human brain tissue. Finally, protein-protein interaction analysis and drug-gene interaction analysis were performed to assess the role of DEGs in epilepsy treatment. RESULTS The study found that the protein tyrosine phosphatase receptor-type O gene (PTPRO) and the growth arrest and DNA damage inducible alpha gene (GADD45A) were significantly upregulated in epileptic rats compared to controls in both datasets. Gene co-expression analysis revealed that PTPRO was co-expressed with RBP4, NDN, PAK3, FOXG1, IDS, and IDS, and GADD45A was co-expressed with LRRK2 in human brain tissue. Expression quantitative trait loci analysis suggested that epilepsy risk single-nucleotide polymorphisms could be responsible for the altered PTPRO and GADD45A expression in human brain tissue. Moreover, the protein encoded by GADD45A had a direct interaction with approved antiepileptic drug targets, and GADD45A interacts with genistein and cisplatin. CONCLUSIONS The results of this study highlight PTPRO and GADD45A as potential genes for the diagnosis and treatment of epilepsy.
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Affiliation(s)
- Shitao Wang
- Department of Neurology, Affiliated Fuyang People's Hospital of Anhui Medical University, Fuyang, 236000, Anhui, China.
| | - Zhenrong Xie
- The Medical Biobank, First Affiliated Hospital of Kunming Medical University, Kunming, 650032, Yunnan, China
| | - Tian Jun
- Department of Neurology, Affiliated Fuyang People's Hospital of Anhui Medical University, Fuyang, 236000, Anhui, China
| | - Xuelu Ma
- Department of Neurology, Affiliated Fuyang People's Hospital of Anhui Medical University, Fuyang, 236000, Anhui, China
| | - Mengen Zhang
- Department of Neurology, Affiliated Fuyang People's Hospital of Anhui Medical University, Fuyang, 236000, Anhui, China
| | - Feng Rao
- Department of Neurology, Affiliated Fuyang People's Hospital of Anhui Medical University, Fuyang, 236000, Anhui, China
| | - Hui Xu
- Department of Neurology, Affiliated Fuyang People's Hospital of Anhui Medical University, Fuyang, 236000, Anhui, China
| | - Jinghong Lu
- Department of Neurology, Affiliated Fuyang People's Hospital of Anhui Medical University, Fuyang, 236000, Anhui, China
| | - Xiangqian Ding
- Department of Neurosurgery, Qilu Hospital of Shandong University, Jinan, 250012, Shandong, China
| | - Zongyou Li
- Department of Neurology, Affiliated Fuyang People's Hospital of Anhui Medical University, Fuyang, 236000, Anhui, China
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2
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Woodward AA, Urbanowicz RJ, Naj AC, Moore JH. Genetic heterogeneity: Challenges, impacts, and methods through an associative lens. Genet Epidemiol 2022; 46:555-571. [PMID: 35924480 PMCID: PMC9669229 DOI: 10.1002/gepi.22497] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Revised: 07/06/2022] [Accepted: 07/19/2022] [Indexed: 01/07/2023]
Abstract
Genetic heterogeneity describes the occurrence of the same or similar phenotypes through different genetic mechanisms in different individuals. Robustly characterizing and accounting for genetic heterogeneity is crucial to pursuing the goals of precision medicine, for discovering novel disease biomarkers, and for identifying targets for treatments. Failure to account for genetic heterogeneity may lead to missed associations and incorrect inferences. Thus, it is critical to review the impact of genetic heterogeneity on the design and analysis of population level genetic studies, aspects that are often overlooked in the literature. In this review, we first contextualize our approach to genetic heterogeneity by proposing a high-level categorization of heterogeneity into "feature," "outcome," and "associative" heterogeneity, drawing on perspectives from epidemiology and machine learning to illustrate distinctions between them. We highlight the unique nature of genetic heterogeneity as a heterogeneous pattern of association that warrants specific methodological considerations. We then focus on the challenges that preclude effective detection and characterization of genetic heterogeneity across a variety of epidemiological contexts. Finally, we discuss systems heterogeneity as an integrated approach to using genetic and other high-dimensional multi-omic data in complex disease research.
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Affiliation(s)
- Alexa A. Woodward
- Department of Biostatistics, Epidemiology and InformaticsUniversity of PennsylvaniaPhiladelphiaPennsylvaniaUSA
| | - Ryan J. Urbanowicz
- Department of Computational BiomedicineCedars‐Sinai Medical CenterLos AngelesCaliforniaUSA
| | - Adam C. Naj
- Department of Biostatistics, Epidemiology and InformaticsUniversity of PennsylvaniaPhiladelphiaPennsylvaniaUSA
| | - Jason H. Moore
- Department of Computational BiomedicineCedars‐Sinai Medical CenterLos AngelesCaliforniaUSA
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Ma P, Wan LP, Li Y, He CH, Song NN, Zhao S, Wang H, Ding YQ, Mao B, Sheng N. RNF220 is an E3 ubiquitin ligase for AMPA receptors to regulate synaptic transmission. SCIENCE ADVANCES 2022; 8:eabq4736. [PMID: 36179027 PMCID: PMC9524831 DOI: 10.1126/sciadv.abq4736] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Accepted: 08/15/2022] [Indexed: 06/12/2023]
Abstract
The accurate expression of postsynaptic AMPA receptors (AMPARs) is critical for information processing in the brain, and ubiquitination is a key regulator for this biological process. However, the roles of E3 ubiquitin ligases in the regulation of AMPARs are poorly understood. Here, we find that RNF220 directly interacts with AMPARs to meditate their polyubiquitination, and RNF220 knockout specifically increases AMPAR protein levels, thereby enhancing basal synaptic activity while impairing synaptic plasticity. Moreover, depending on its E3 ubiquitin ligase activity, RNF220 represses AMPAR-mediated excitatory synaptic responses and their neuronal surface expression. Furthermore, learning and memory are altered in forebrain RNF220-deficient mice. In addition, two neuropathology-related RNF220 variants fail to repress excitatory synaptic activity because of the incapability to regulate AMPAR ubiquitination due to their attenuated interaction. Together, we identify RNF220 as an E3 ubiquitin ligase for AMPARs and establish its substantial role in excitatory synaptic transmission and brain function.
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Affiliation(s)
- Pengcheng Ma
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, China
| | - Li Pear Wan
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, China
- Kunming College of Life Science, University of Chinese Academy of Sciences, Kunming 650223, China
| | - Yuwei Li
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, China
- Kunming College of Life Science, University of Chinese Academy of Sciences, Kunming 650223, China
| | - Chun-Hui He
- Key Laboratory of Arrhythmias, Ministry of Education of China, East Hospital, and Department of Anatomy and Neurobiology, Tongji University School of Medicine, Shanghai 200092, China
| | - Ning-Ning Song
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200032, China
- Department of Laboratory Animal Science, Fudan University, Shanghai 200032, China
| | - Shiping Zhao
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, China
| | - Huishan Wang
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, China
- Kunming College of Life Science, University of Chinese Academy of Sciences, Kunming 650223, China
| | - Yu-Qiang Ding
- Key Laboratory of Arrhythmias, Ministry of Education of China, East Hospital, and Department of Anatomy and Neurobiology, Tongji University School of Medicine, Shanghai 200092, China
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200032, China
- Department of Laboratory Animal Science, Fudan University, Shanghai 200032, China
| | - Bingyu Mao
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, China
- Center for Excellence in Animal Evolution and Genetics, Chinese Academy of Sciences, Kunming 650223, China
| | - Nengyin Sheng
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, China
- Center for Excellence in Animal Evolution and Genetics, Chinese Academy of Sciences, Kunming 650223, China
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4
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Dunn PJ, Maher BH, Albury CL, Stuart S, Sutherland HG, Maksemous N, Benton MC, Smith RA, Haupt LM, Griffiths LR. Tiered analysis of whole-exome sequencing for epilepsy diagnosis. Mol Genet Genomics 2020; 295:751-763. [DOI: 10.1007/s00438-020-01657-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Accepted: 02/19/2020] [Indexed: 12/11/2022]
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5
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Souza IA, Gandini MA, Zhang FX, Mitchell WG, Matsumoto J, Lerner J, Pierson TM, Zamponi GW. Pathogenic Cav3.2 channel mutation in a child with primary generalized epilepsy. Mol Brain 2019; 12:86. [PMID: 31651342 PMCID: PMC6814130 DOI: 10.1186/s13041-019-0509-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Accepted: 10/02/2019] [Indexed: 12/31/2022] Open
Abstract
Two paternally-inherited missense variants in CACNA1H were identified and characterized in a 6-year-old child with generalized epilepsy. Febrile and unprovoked seizures were present in this child. Both variants were expressed in cis or isolation using human recombinant Cav3.2 calcium channels in tsA-201 cells. Whole-cell patch-clamp recordings indicated that one variant (c.3844C > T; p.R1282W) caused a significant increase in current density consistent with a pathogenic gain-of-function phenotype; while the other cis-related variant (c.5294C > T; p.A1765V) had a benign profile.
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Affiliation(s)
- Ivana A Souza
- Department of Physiology and Pharmacology, Alberta Children's Hospital Research Institute, Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, 3330 Hospital Dr. NW, Calgary, AB, T2N 4N1, Canada
| | - Maria A Gandini
- Department of Physiology and Pharmacology, Alberta Children's Hospital Research Institute, Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, 3330 Hospital Dr. NW, Calgary, AB, T2N 4N1, Canada
| | - Fang-Xiong Zhang
- Department of Physiology and Pharmacology, Alberta Children's Hospital Research Institute, Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, 3330 Hospital Dr. NW, Calgary, AB, T2N 4N1, Canada
| | - Wendy G Mitchell
- Neurology Division, Children's Hospital Los Angeles & Department of Neurology, Keck School of Medicine of University of Southern California, Los Angeles, USA
| | - Joyce Matsumoto
- Department of Pediatrics, Division of Pediatric Neurology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Jason Lerner
- Department of Pediatrics, Division of Pediatric Neurology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Tyler Mark Pierson
- Department of Pediatrics, Cedars-Sinai Medical Center, Los Angeles, CA, USA.,Department of Neurology, Cedars-Sinai Medical Center, Los Angeles, CA, USA.,Board of Governors Regenerative Medicine Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Gerald W Zamponi
- Department of Physiology and Pharmacology, Alberta Children's Hospital Research Institute, Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, 3330 Hospital Dr. NW, Calgary, AB, T2N 4N1, Canada.
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6
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Hernandez CC, Macdonald RL. A structural look at GABA A receptor mutations linked to epilepsy syndromes. Brain Res 2019; 1714:234-247. [PMID: 30851244 DOI: 10.1016/j.brainres.2019.03.004] [Citation(s) in RCA: 58] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 02/25/2019] [Accepted: 03/06/2019] [Indexed: 12/12/2022]
Abstract
Understanding the genetic variation in GABAA receptor subunit genes (GABRs), GABRA1-6, GABRB1-3, GABRG1-3 and GABRD, in individuals affected by epilepsy may improve the diagnosis and treatment of epilepsy syndromes through identification of disease-associated variants. However, the lack of functional analysis and validation of many novel and previously reported familial and de novo mutations have made it challenging to address meaningful gene associations with epilepsy syndromes. GABAA receptors belong to the Cys-loop receptor family. Even though GABAA receptor mutant residues are widespread among different GABRs, their frequent occurrence in important structural domains that share common functional features suggests associations between structure and function.
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Affiliation(s)
- Ciria C Hernandez
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA.
| | - Robert L Macdonald
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN, USA
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7
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Kothur K, Holman K, Farnsworth E, Ho G, Lorentzos M, Troedson C, Gupta S, Webster R, Procopis PG, Menezes MP, Antony J, Ardern-Holmes S, Dale RC, Christodoulou J, Gill D, Bennetts B. Diagnostic yield of targeted massively parallel sequencing in children with epileptic encephalopathy. Seizure 2018; 59:132-140. [DOI: 10.1016/j.seizure.2018.05.005] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Revised: 02/20/2018] [Accepted: 05/08/2018] [Indexed: 12/28/2022] Open
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8
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Radhakrishnan A, Menon R, Abraham M, Vilanilam G, Sharma S, Thomas B, Kesavadas C, Cherian A, Varma R, Thomas SV. Predictors of outcome after surgery in 134 children with drug-resistant TLE. Epilepsy Res 2018; 139:150-156. [DOI: 10.1016/j.eplepsyres.2017.11.020] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2017] [Revised: 11/23/2017] [Accepted: 11/29/2017] [Indexed: 12/01/2022]
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9
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Wu SZ, Ye H, Yang XG, Lu ZL, Qu Q, Qu J. Case-control pharmacogenetic study of HCN1/HCN2 variants and genetic generalized epilepsies. Clin Exp Pharmacol Physiol 2017; 45:226-233. [PMID: 29047147 DOI: 10.1111/1440-1681.12877] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Revised: 10/06/2017] [Accepted: 10/12/2017] [Indexed: 11/27/2022]
Abstract
Epilepsy is a common complex neurological disorder, and some forms are resistant to drug treatment. The HCN1/HCN2 genes encode hyperpolarization-activated cyclic nucleotide-gated channels, which play important roles in the electrophysiology of neurons. We investigated the association between HCN1/HCN2 variants and drug resistance or the risk of genetic generalized epilepsies (GGEs). We used matrix-assisted laser desorption/ionization time-of-flight mass spectrometry to assess nine variants of HCN1/HCN2 in 284 healthy participants and 483 GGEs (279 drug-responsive, 204 drug-resistant). Frequencies of HCN2 rs7255568 and rs3752158 G alleles differed in GGEs and in controls (P = .039, P = .027, respectively). The frequency of HCN2 haplotype (CAC) was higher in patients than controls (P = .046). The frequency of the HCN1 rs10462087 CC+CT genotype was lower in patients with childhood absence epilepsy (CAE) than controls (P = .047). Rs7255568 was associated with the risk of CAE (P = .028) and juvenile myoclonic epilepsy (JME) (P = .02). Rs3752158 was associated with the risk of generalized tonic-clonic seizures, JME, and febrile seizures (all P < .05). The frequency of the HCN2 haplotype (CAC) was higher in patients with JME (P = .015) and in those with febrile seizures (P = .024) than in controls. No significant association was found between HCN1/HCN2 alleles, genotypes or haplotypes, and drug resistance in patients. After Bonferroni's multiple comparisons correction, only the HCN2 rs3752158 C allele and GC+CC genotype frequencies in patients with JME were higher than those in controls (19.2% vs 11.6%, odds ratio (OR) = 1.71, 95% CI = 1.18-2.32), P = .004 < 0.05/9; 36% vs 22.2%, OR = 1.62(1.18-2.23), P = .003 < 0.05/9). Our study suggests that HCN2 rs3752158 is involved in the susceptibility to JME.
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Affiliation(s)
- Shu-Zhi Wu
- Department of Neurology, The Third Clinical Institute Affiliated to Wenzhou Medical University & Wenzhou People's Hospital, Wenzhou, China
| | - Hua Ye
- Department of Neurology, The Third Clinical Institute Affiliated to Wenzhou Medical University & Wenzhou People's Hospital, Wenzhou, China
| | - Xiao-Guo Yang
- Department of Neurology, The Third Clinical Institute Affiliated to Wenzhou Medical University & Wenzhou People's Hospital, Wenzhou, China
| | - Zhi-Li Lu
- Department of Pathology, Hunan Cancer Hospital, Central South University, Changsha, China
| | - Qiang Qu
- Department of Pharmacy, Xiangya Hospital, Central South University, Changsha, China
| | - Jian Qu
- Department of Pharmacy, The Second Xiangya Hospital, Central South University, Changsha, China.,Institute of Clinical Pharmacy, Central South University, Changsha, China
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10
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Mirza N, Vasieva O, Appleton R, Burn S, Carr D, Crooks D, du Plessis D, Duncan R, Farah JO, Josan V, Miyajima F, Mohanraj R, Shukralla A, Sills GJ, Marson AG, Pirmohamed M. An integrative in silico system for predicting dysregulated genes in the human epileptic focus: Application to SLC transporters. Epilepsia 2016; 57:1467-74. [PMID: 27421837 DOI: 10.1111/epi.13473] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/20/2016] [Indexed: 11/29/2022]
Abstract
OBJECTIVE Many different gene families are currently being investigated for their potential role in epilepsy and in the response to antiepileptic drugs. A common research challenge is identifying the members of a gene family that are most significantly dysregulated within the human epileptic focus, before taking them forward for resource-intensive functional studies. Published data about transcriptomic changes within the human epileptic focus remains incomplete. A need exists for an accurate in silico system for the prediction of dysregulated genes within the epileptic focus. We present such a bioinformatic system. We demonstrate the validity of our approach by applying it to the solute carrier (SLC) gene family. There are >400 known SLCs. SLCs have never been systematically studied in epilepsy. METHODS Using our in silico system, we predicted the SLCs likely to be dysregulated in the epileptic focus. We validated our in silico predictions by identifying ex vivo the SLCs dysregulated in epileptic foci, and determining the overlap between our in silico and ex vivo results. For the ex vivo analysis, we used a custom oligonucleotide microarray containing exon probes for all known SLCs to analyze 24 hippocampal samples obtained from surgery for pharmacoresistant mesial temporal lobe epilepsy and 24 hippocampal samples from normal postmortem controls. RESULTS There was a highly significant (p < 9.99 × 10(-7) ) overlap between the genes identified by our in silico and ex vivo strategies. The SLCs identified were either metal ion exchangers or neurotransmitter transporters, which are likely to play a part in epilepsy by influencing neuronal excitability. SIGNIFICANCE The identified SLCs are most likely to mediate pharmacoresistance in epilepsy by enhancing the intrinsic severity of epilepsy, but further functional work will be needed to fully evaluate their role. Our successful in silico strategy can be adapted in order to prioritize genes relevant to epilepsy from other gene families.
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Affiliation(s)
- Nasir Mirza
- Department of Molecular & Clinical Pharmacology, University of Liverpool, Liverpool, United Kingdom
| | - Olga Vasieva
- Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Richard Appleton
- The Roald Dahl EEG Unit, Paediatric Neurosciences Foundation, Alder Hey Children's NHS Foundation Trust, Liverpool, United Kingdom
| | - Sasha Burn
- Department of Neurosurgery, Alder Hey Children's NHS Foundation Trust, Liverpool, United Kingdom
| | - Daniel Carr
- Department of Molecular & Clinical Pharmacology, University of Liverpool, Liverpool, United Kingdom
| | - Daniel Crooks
- Department of Neuropathology, The Walton Centre NHS Foundation Trust, Liverpool, United Kingdom
| | - Daniel du Plessis
- Department of Cellular Pathology, Salford Royal NHS Foundation Trust, Salford, United Kingdom
| | - Roderick Duncan
- Department of Neurology, Christchurch Hospital, Christchurch, New Zealand
| | - Jibril Osman Farah
- Department of Neurosurgery, The Walton Centre NHS Foundation Trust, Liverpool, United Kingdom
| | - Vivek Josan
- Department of Neurosurgery, Salford Royal NHS Foundation Trust, Salford, United Kingdom
| | - Fabio Miyajima
- Department of Molecular & Clinical Pharmacology, University of Liverpool, Liverpool, United Kingdom
| | - Rajiv Mohanraj
- Department of Neurology, Salford Royal NHS Foundation Trust, Salford, United Kingdom
| | - Arif Shukralla
- Department of Neurology, Salford Royal NHS Foundation Trust, Salford, United Kingdom
| | - Graeme J Sills
- Department of Molecular & Clinical Pharmacology, University of Liverpool, Liverpool, United Kingdom
| | - Anthony G Marson
- Department of Molecular & Clinical Pharmacology, University of Liverpool, Liverpool, United Kingdom
| | - Munir Pirmohamed
- Department of Molecular & Clinical Pharmacology, University of Liverpool, Liverpool, United Kingdom
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Loss of function of the retinoid-related nuclear receptor (RORB) gene and epilepsy. Eur J Hum Genet 2016; 24:1761-1770. [PMID: 27352968 DOI: 10.1038/ejhg.2016.80] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Revised: 05/01/2016] [Accepted: 05/20/2016] [Indexed: 12/11/2022] Open
Abstract
Genetic generalized epilepsy (GGE), formerly known as idiopathic generalized epilepsy, is the most common form of epilepsy and is thought to have predominant genetic etiology. GGE are clinically characterized by absence, myoclonic, or generalized tonic-clonic seizures with electroencephalographic pattern of bilateral, synchronous, and symmetrical spike-and-wave discharges. Despite their strong heritability, the genetic basis of generalized epilepsies remains largely elusive. Nevertheless, recent advances in genetic technology have led to the identification of numerous genes and genomic defects in various types of epilepsies in the past few years. In the present study, we performed whole-exome sequencing in a family with GGE consistent with the diagnosis of eyelid myoclonia with absences. We found a nonsense variant (c.196C>T/p.(Arg66*)) in RORB, which encodes the beta retinoid-related orphan nuclear receptor (RORβ), in four affected family members. In addition, two de novo variants (c.218T>C/p.(Leu73Pro); c.1249_1251delACG/p.(Thr417del)) were identified in sporadic patients by trio-based exome sequencing. We also found two de novo deletions in patients with behavioral and cognitive impairment and epilepsy: a 52-kb microdeletion involving exons 5-10 of RORB and a larger 9q21-microdeletion. Furthermore, we identified a patient with intellectual disability and a balanced translocation where one breakpoint truncates RORB and refined the phenotype of a recently reported patient with RORB deletion. Our data support the role of RORB gene variants/CNVs in neurodevelopmental disorders including epilepsy, and especially in generalized epilepsies with predominant absence seizures.
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12
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Souza IA, Gandini MA, Wan MM, Zamponi GW. Two heterozygous Cav3.2 channel mutations in a pediatric chronic pain patient: recording condition-dependent biophysical effects. Pflugers Arch 2015; 468:635-42. [DOI: 10.1007/s00424-015-1776-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2015] [Revised: 12/14/2015] [Accepted: 12/16/2015] [Indexed: 11/24/2022]
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13
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14
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Wolf P, Yacubian EMT, Avanzini G, Sander T, Schmitz B, Wandschneider B, Koepp M. Juvenile myoclonic epilepsy: A system disorder of the brain. Epilepsy Res 2015; 114:2-12. [DOI: 10.1016/j.eplepsyres.2015.04.008] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Accepted: 04/14/2015] [Indexed: 12/28/2022]
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15
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Lal D, Pernhorst K, Klein KM, Reif P, Tozzi R, Toliat MR, Winterer G, Neubauer B, Nürnberg P, Rosenow F, Becker F, Lerche H, Kunz WS, Kurki MI, Hoffmann P, Becker AJ, Perucca E, Zara F, Sander T, Weber YG. Extending the phenotypic spectrum ofRBFOX1deletions: Sporadic focal epilepsy. Epilepsia 2015; 56:e129-33. [DOI: 10.1111/epi.13076] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/10/2015] [Indexed: 12/11/2022]
Affiliation(s)
- Dennis Lal
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD); University of Cologne; Cologne Germany
- Department of Neuropediatrics; University Medical Center Giessen and Marburg; Giessen Germany
- Cologne Center for Genomics; University of Cologne; Cologne Germany
| | | | | | - Philipp Reif
- Department of Neurology; University of Marburg; Marburg Germany
| | - Rossana Tozzi
- C. Mondino National Neurological Institute; Pavia Italy
| | - Mohammad R. Toliat
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD); University of Cologne; Cologne Germany
| | - Georg Winterer
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD); University of Cologne; Cologne Germany
| | - Bernd Neubauer
- Department of Neuropediatrics; University Medical Center Giessen and Marburg; Giessen Germany
| | - Peter Nürnberg
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD); University of Cologne; Cologne Germany
| | - Felix Rosenow
- Department of Neurology; University of Marburg; Marburg Germany
| | - Felicitas Becker
- Department of Neurology and Epileptology; Hertie Institute for Clinical Brain Research; University of Tübingen; Tübingen Germany
| | - Holger Lerche
- Department of Neurology and Epileptology; Hertie Institute for Clinical Brain Research; University of Tübingen; Tübingen Germany
| | | | - Mitja I. Kurki
- Psychiatric and Neurodevelopmental Genetics Unit; Massachusetts General Hospital; Boston Massachusetts U.S.A
- Broad Institute of Harvard and MIT; Cambridge Massachusetts U.S.A
- Neurosurgery; NeuroCenter; Kuopio University Hospital; Kuopio Finland
| | - Per Hoffmann
- Institute of Human Genetics; University of Bonn; Bonn Germany
- Division of Medical Genetics; University Hospital; Basel Switzerland
- Department of Biomedicine; University of Basel; Basel Switzerland
| | | | - Emilio Perucca
- C. Mondino National Neurological Institute; Pavia Italy
- Department of Internal Medicine and Therapeutics; University of Pavia; Pavia Italy
| | - Federico Zara
- Laboratory of Neurogenetics; Neuromuscular Disease Unit; Istituto G. Gaslini; Genova Italy
| | - Thomas Sander
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD); University of Cologne; Cologne Germany
| | - Yvonne G. Weber
- Department of Neurology and Epileptology; Hertie Institute for Clinical Brain Research; University of Tübingen; Tübingen Germany
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Lal D, Ruppert AK, Trucks H, Schulz H, de Kovel CG, Kasteleijn-Nolst Trenité D, Sonsma ACM, Koeleman BP, Lindhout D, Weber YG, Lerche H, Kapser C, Schankin CJ, Kunz WS, Surges R, Elger CE, Gaus V, Schmitz B, Helbig I, Muhle H, Stephani U, Klein KM, Rosenow F, Neubauer BA, Reinthaler EM, Zimprich F, Feucht M, Møller RS, Hjalgrim H, De Jonghe P, Suls A, Lieb W, Franke A, Strauch K, Gieger C, Schurmann C, Schminke U, Nürnberg P, Sander T. Burden analysis of rare microdeletions suggests a strong impact of neurodevelopmental genes in genetic generalised epilepsies. PLoS Genet 2015; 11:e1005226. [PMID: 25950944 PMCID: PMC4423931 DOI: 10.1371/journal.pgen.1005226] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2014] [Accepted: 04/16/2015] [Indexed: 01/06/2023] Open
Abstract
Genetic generalised epilepsy (GGE) is the most common form of genetic epilepsy, accounting for 20% of all epilepsies. Genomic copy number variations (CNVs) constitute important genetic risk factors of common GGE syndromes. In our present genome-wide burden analysis, large (≥ 400 kb) and rare (< 1%) autosomal microdeletions with high calling confidence (≥ 200 markers) were assessed by the Affymetrix SNP 6.0 array in European case-control cohorts of 1,366 GGE patients and 5,234 ancestry-matched controls. We aimed to: 1) assess the microdeletion burden in common GGE syndromes, 2) estimate the relative contribution of recurrent microdeletions at genomic rearrangement hotspots and non-recurrent microdeletions, and 3) identify potential candidate genes for GGE. We found a significant excess of microdeletions in 7.3% of GGE patients compared to 4.0% in controls (P = 1.8 x 10-7; OR = 1.9). Recurrent microdeletions at seven known genomic hotspots accounted for 36.9% of all microdeletions identified in the GGE cohort and showed a 7.5-fold increased burden (P = 2.6 x 10-17) relative to controls. Microdeletions affecting either a gene previously implicated in neurodevelopmental disorders (P = 8.0 x 10-18, OR = 4.6) or an evolutionarily conserved brain-expressed gene related to autism spectrum disorder (P = 1.3 x 10-12, OR = 4.1) were significantly enriched in the GGE patients. Microdeletions found only in GGE patients harboured a high proportion of genes previously associated with epilepsy and neuropsychiatric disorders (NRXN1, RBFOX1, PCDH7, KCNA2, EPM2A, RORB, PLCB1). Our results demonstrate that the significantly increased burden of large and rare microdeletions in GGE patients is largely confined to recurrent hotspot microdeletions and microdeletions affecting neurodevelopmental genes, suggesting a strong impact of fundamental neurodevelopmental processes in the pathogenesis of common GGE syndromes.
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Affiliation(s)
- Dennis Lal
- Cologne Center for Genomics (CCG), University of Cologne, Cologne, Germany
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
- Department of Neuropediatrics, University Medical Center Giessen and Marburg, Giessen, Germany
- EPICURE Consortium
| | - Ann-Kathrin Ruppert
- Cologne Center for Genomics (CCG), University of Cologne, Cologne, Germany
- EPICURE Consortium
| | - Holger Trucks
- Cologne Center for Genomics (CCG), University of Cologne, Cologne, Germany
- EPICURE Consortium
| | - Herbert Schulz
- Cologne Center for Genomics (CCG), University of Cologne, Cologne, Germany
- EPICURE Consortium
| | - Carolien G. de Kovel
- EPICURE Consortium
- Department of Medical Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | | | - Anja C. M. Sonsma
- EPICURE Consortium
- Department of Medical Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Bobby P. Koeleman
- EPICURE Consortium
- Department of Medical Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Dick Lindhout
- EPICURE Consortium
- Department of Medical Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
- SEIN Epilepsy Institute in the Netherlands, Hoofddorp, The Netherlands
| | - Yvonne G. Weber
- EPICURE Consortium
- Department of Neurology and Epileptology, Hertie Institute of Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Holger Lerche
- EPICURE Consortium
- Department of Neurology and Epileptology, Hertie Institute of Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Claudia Kapser
- EPICURE Consortium
- Department of Neurology, University of Munich Hospital—Großhadern, Munich, Germany
| | - Christoph J. Schankin
- EPICURE Consortium
- Department of Neurology, University of Munich Hospital—Großhadern, Munich, Germany
| | - Wolfram S. Kunz
- EPICURE Consortium
- Department of Epileptology, University Clinics Bonn, Bonn, Germany
| | - Rainer Surges
- EPICURE Consortium
- Department of Epileptology, University Clinics Bonn, Bonn, Germany
| | - Christian E. Elger
- EPICURE Consortium
- Department of Epileptology, University Clinics Bonn, Bonn, Germany
| | - Verena Gaus
- EPICURE Consortium
- Department of Neurology, Charité University Medicine, Campus Virchow Clinic, Berlin, Germany
| | - Bettina Schmitz
- EPICURE Consortium
- Department of Neurology, Charité University Medicine, Campus Virchow Clinic, Berlin, Germany
- Department of Neurology, Vivantes Humboldt-Klinikum, Berlin, Germany
| | - Ingo Helbig
- EPICURE Consortium
- Department of Neuropediatrics, University Medical Center Schleswig-Holstein (Kiel Campus), Kiel, Germany
| | - Hiltrud Muhle
- EPICURE Consortium
- Department of Neuropediatrics, University Medical Center Schleswig-Holstein (Kiel Campus), Kiel, Germany
| | - Ulrich Stephani
- EPICURE Consortium
- Department of Neuropediatrics, University Medical Center Schleswig-Holstein (Kiel Campus), Kiel, Germany
| | - Karl M. Klein
- EPICURE Consortium
- Epilepsy-Center Hessen, Department of Neurology, Philipps-University Marburg, Marburg, Germany
- Epilepsy Center Frankfurt Rhein-Main, Department of Neurology, Johann Wolfgang Goethe University Frankfurt, Frankfurt, Germany
| | - Felix Rosenow
- EPICURE Consortium
- Epilepsy-Center Hessen, Department of Neurology, Philipps-University Marburg, Marburg, Germany
- Epilepsy Center Frankfurt Rhein-Main, Department of Neurology, Johann Wolfgang Goethe University Frankfurt, Frankfurt, Germany
| | - Bernd A. Neubauer
- Department of Neuropediatrics, University Medical Center Giessen and Marburg, Giessen, Germany
| | - Eva M. Reinthaler
- EPICURE Consortium
- Department of Neurology, Medical University of Vienna, Vienna, Austria
| | - Fritz Zimprich
- EPICURE Consortium
- Department of Neurology, Medical University of Vienna, Vienna, Austria
| | - Martha Feucht
- EPICURE Consortium
- Department of Pediatrics and Neonatology, Medical University of Vienna, Vienna, Austria
| | - Rikke S. Møller
- EPICURE Consortium
- Department of Neurology, Danish Epilepsy Centre, Dianalund, Denmark
- Institute for Regional Health Services, University of Southern Denmark, Odense, Denmark
| | - Helle Hjalgrim
- EPICURE Consortium
- Department of Neurology, Danish Epilepsy Centre, Dianalund, Denmark
- Institute for Regional Health Services, University of Southern Denmark, Odense, Denmark
| | - Peter De Jonghe
- EPICURE Consortium
- Neurogenetics Group, VIB Department of Molecular Genetics, University of Antwerp, Antwerp, Belgium
- Laboratory of Neurogenetics, Institute Born-Bunge, University of Antwerp, Antwerp, Belgium
| | - Arvid Suls
- EPICURE Consortium
- Neurogenetics Group, VIB Department of Molecular Genetics, University of Antwerp, Antwerp, Belgium
- Laboratory of Neurogenetics, Institute Born-Bunge, University of Antwerp, Antwerp, Belgium
| | - Wolfgang Lieb
- Institute of Epidemiology and Biobank Popgen, Christian Albrechts University, Kiel, Germany
| | - Andre Franke
- Institute of Clinical Molecular Biology, Christian-Albrechts-University of Kiel, Kiel, Germany
| | - Konstantin Strauch
- Institute of Genetic Epidemiology, Helmholtz Zentrum München—German Research Center for Environmental Health, Neuherberg, Germany
- Institute of Medical Informatics, Biometry and Epidemiology, and Chair of Genetic Epidemiology, Ludwig-Maximilians-University, Munich, Germany
| | - Christian Gieger
- Institute of Genetic Epidemiology, Helmholtz Zentrum München—German Research Center for Environmental Health, Neuherberg, Germany
- Research Unit of Molecular Epidemiology, Helmholtz Zentrum München—German Research Center for Environmental Health, Neuherberg, Germany
- Institute of Epidemiology II, Helmholtz Zentrum München—German Research Center for Environmental Health, Neuherberg, Germany
| | - Claudia Schurmann
- Interfaculty Institute for Genetics and Functional Genomics, Ernst Moritz Arndt University, Greifswald, Germany
| | - Ulf Schminke
- Department of Neurology, University Medicine Greifswald, Ernst Moritz Arndt University, Greifswald, Germany
| | - Peter Nürnberg
- Cologne Center for Genomics (CCG), University of Cologne, Cologne, Germany
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
- EPICURE Consortium
- Center for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany
| | | | - Thomas Sander
- Cologne Center for Genomics (CCG), University of Cologne, Cologne, Germany
- EPICURE Consortium
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Abstract
Background The epilepsies are a clinically heterogeneous group of neurological disorders. Despite strong evidence for heritability, genome-wide association studies have had little success in identification of risk loci associated with epilepsy, probably because of relatively small sample sizes and insufficient power. We aimed to identify risk loci through meta-analyses of genome-wide association studies for all epilepsy and the two largest clinical subtypes (genetic generalised epilepsy and focal epilepsy). Methods We combined genome-wide association data from 12 cohorts of individuals with epilepsy and controls from population-based datasets. Controls were ethnically matched with cases. We phenotyped individuals with epilepsy into categories of genetic generalised epilepsy, focal epilepsy, or unclassified epilepsy. After standardised filtering for quality control and imputation to account for different genotyping platforms across sites, investigators at each site conducted a linear mixed-model association analysis for each dataset. Combining summary statistics, we conducted fixed-effects meta-analyses of all epilepsy, focal epilepsy, and genetic generalised epilepsy. We set the genome-wide significance threshold at p<1·66 × 10−8. Findings We included 8696 cases and 26 157 controls in our analysis. Meta-analysis of the all-epilepsy cohort identified loci at 2q24.3 (p=8·71 × 10−10), implicating SCN1A, and at 4p15.1 (p=5·44 × 10−9), harbouring PCDH7, which encodes a protocadherin molecule not previously implicated in epilepsy. For the cohort of genetic generalised epilepsy, we noted a single signal at 2p16.1 (p=9·99 × 10−9), implicating VRK2 or FANCL. No single nucleotide polymorphism achieved genome-wide significance for focal epilepsy. Interpretation This meta-analysis describes a new locus not previously implicated in epilepsy and provides further evidence about the genetic architecture of these disorders, with the ultimate aim of assisting in disease classification and prognosis. The data suggest that specific loci can act pleiotropically raising risk for epilepsy broadly, or can have effects limited to a specific epilepsy subtype. Future genetic analyses might benefit from both lumping (ie, grouping of epilepsy types together) or splitting (ie, analysis of specific clinical subtypes). Funding International League Against Epilepsy and multiple governmental and philanthropic agencies.
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Dejanovic B, Lal D, Catarino CB, Arjune S, Belaidi AA, Trucks H, Vollmar C, Surges R, Kunz WS, Motameny S, Altmüller J, Köhler A, Neubauer BA, EPICURE Consortium, Nürnberg P, Noachtar S, Schwarz G, Sander T. Exonic microdeletions of the gephyrin gene impair GABAergic synaptic inhibition in patients with idiopathic generalized epilepsy. Neurobiol Dis 2014; 67:88-96. [DOI: 10.1016/j.nbd.2014.02.001] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Revised: 01/09/2014] [Accepted: 02/10/2014] [Indexed: 12/29/2022] Open
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Puskarjov M, Seja P, Heron SE, Williams TC, Ahmad F, Iona X, Oliver KL, Grinton BE, Vutskits L, Scheffer IE, Petrou S, Blaesse P, Dibbens LM, Berkovic SF, Kaila K. A variant of KCC2 from patients with febrile seizures impairs neuronal Cl- extrusion and dendritic spine formation. EMBO Rep 2014; 15:723-9. [PMID: 24668262 PMCID: PMC4197883 DOI: 10.1002/embr.201438749] [Citation(s) in RCA: 129] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2014] [Accepted: 03/10/2014] [Indexed: 11/11/2022] Open
Abstract
Genetic variation in SLC12A5 which encodes KCC2, the neuron-specific cation-chloride cotransporter that is essential for hyperpolarizing GABAergic signaling and formation of cortical dendritic spines, has not been reported in human disease. Screening of SLC12A5 revealed a co-segregating variant (KCC2-R952H) in an Australian family with febrile seizures. We show that KCC2-R952H reduces neuronal Cl(-) extrusion and has a compromised ability to induce dendritic spines in vivo and in vitro. Biochemical analyses indicate a reduced surface expression of KCC2-R952H which likely contributes to the functional deficits. Our data suggest that KCC2-R952H is a bona fide susceptibility variant for febrile seizures.
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Affiliation(s)
- Martin Puskarjov
- Department of Biosciences, University of Helsinki, Helsinki, Finland Neuroscience Center, University of Helsinki, Helsinki, Finland
| | - Patricia Seja
- Department of Biosciences, University of Helsinki, Helsinki, Finland Neuroscience Center, University of Helsinki, Helsinki, Finland
| | - Sarah E Heron
- Epilepsy Research Program, School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, SA, Australia Sansom Institute for Health Research, University of South Australia, Adelaide SA, Australia
| | - Tristiana C Williams
- Epilepsy Research Program, School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, SA, Australia
| | - Faraz Ahmad
- Department of Biosciences, University of Helsinki, Helsinki, Finland Neuroscience Center, University of Helsinki, Helsinki, Finland
| | - Xenia Iona
- Epilepsy Research Program, School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, SA, Australia
| | - Karen L Oliver
- Department of Medicine, Epilepsy Research Center, The University of Melbourne Austin Health, Melbourne Vic., Australia
| | - Bronwyn E Grinton
- Department of Paediatrics, Florey Institute, Royal Children's Hospital The University of Melbourne, Melbourne, Vic., Australia
| | - Laszlo Vutskits
- Department of Anesthesiology, Pharmacology and Intensive Care, University Hospital of Geneva, Geneva, Switzerland
| | - Ingrid E Scheffer
- Department of Medicine, Epilepsy Research Center, The University of Melbourne Austin Health, Melbourne Vic., Australia Department of Paediatrics, Florey Institute, Royal Children's Hospital The University of Melbourne, Melbourne, Vic., Australia
| | - Steven Petrou
- Florey Institute of Neuroscience and Mental Health and the Center for Neural Engineering, The University of Melbourne, Parkville, Vic., Australia
| | - Peter Blaesse
- Department of Biosciences, University of Helsinki, Helsinki, Finland Institute of Physiology I, Westfälische Wilhelms-University Münster, Münster, Germany
| | - Leanne M Dibbens
- Epilepsy Research Program, School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, SA, Australia Sansom Institute for Health Research, University of South Australia, Adelaide SA, Australia
| | - Samuel F Berkovic
- Department of Medicine, Epilepsy Research Center, The University of Melbourne Austin Health, Melbourne Vic., Australia
| | - Kai Kaila
- Department of Biosciences, University of Helsinki, Helsinki, Finland Neuroscience Center, University of Helsinki, Helsinki, Finland
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Viitmaa R, Cizinauskas S, Orro T, Niilo-Rämä M, Gordin E, Lohi H, Seppälä EH, Bragge H, Snellman M. Phenotype, inheritance characteristics, and risk factors for idiopathic epilepsy in Finnish Spitz dogs. J Am Vet Med Assoc 2014; 243:1001-9. [PMID: 24050567 DOI: 10.2460/javma.243.7.1001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To determine the phenotype, inheritance characteristics, and risk factors for idiopathic epilepsy (IE) in Finnish Spitz dogs (FSDs). DESIGN Prospective epidemiological study. ANIMALS 2,141 FSDs. PROCEDURES From 2003 to 2004, questionnaires (n = 5,960) were sent to all owners of 1-to 10-year-old FSDs in Finland. Phone interviews were performed 1 to 2 years later. RESULTS Estimated prevalence of IE was 5.36% (111/2,069 of FSDs that were still alive). Males were predisposed to IE. The median age of onset was 3 years (range, 0.6 to 10 years). The median seizure frequency was 2 seizures/y (range, 0.5 to 48 seizures/y), and the median duration of the seizure episode was 11.75 minutes (range, 1.5 to 90 minutes). The majority (85%) of the seizures had a focal onset, and 54% were characterized as generalized secondary. A generalized seizure phase was determined to be a risk factor for development of progressive disease. Factors associated with the occurrence of a generalized phase were the age of onset, duration of the seizure, number of feeding times per day, and whether the dog was used for hunting. The seizures were not progressing in 678% of the dogs and were easily controlled by antiepileptic treatment in 78.9% of the dogs. The heritability estimate of IE in FSDs was 0.22; IE was best explained as a polygenic trait. CONCLUSIONS AND CLINICAL RELEVANCE In the present study conducted in Finland, complex focal seizures were the most common seizure type for FSDs with IE, and a generalized seizure phase was a risk factor for progression of the disease. Results suggested a benign course of epilepsy in FSDs.
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Affiliation(s)
- Ranno Viitmaa
- Department of Equine and Small Animal Medicine, University of Helsinki, 00014 Helsinki, Finland., Institute of Veterinary Medicine and Animal Sciences, Estonian University of Life Sciences, 51014 Tartu, Estonia
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Winawer MR, Klassen TL, Teed S, Shipman M, Leung EH, Palmer AA. A locus on mouse Ch10 influences susceptibility to limbic seizure severity: fine mapping and in silico candidate gene analysis. GENES BRAIN AND BEHAVIOR 2014; 13:341-9. [PMID: 24373497 DOI: 10.1111/gbb.12116] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2013] [Revised: 11/19/2013] [Accepted: 12/16/2013] [Indexed: 11/29/2022]
Abstract
Identification of genes contributing to mouse seizure susceptibility can reveal novel genes or pathways that provide insight into human epilepsy. Using mouse chromosome substitution strains and interval-specific congenic strains (ISCS), we previously identified an interval conferring pilocarpine-induced limbic seizure susceptibility on distal mouse chromosome 10 (Ch10). We narrowed the region by generating subcongenics with smaller A/J Ch10 segments on a C57BL/6J (B6) background and tested them with pilocarpine. We also tested pilocarpine-susceptible congenics for 6-Hz ECT (electroconvulsive threshold), another model of limbic seizure susceptibility, to determine whether the susceptibility locus might have a broad effect on neuronal hyperexcitability across more than one mode of limbic seizure induction. The ISCS Line 1, which contained the distal 2.7 Mb segment from A/J (starting at rs29382217), was more susceptible to both pilocarpine and ECT. Line 2, which was a subcongenic of Line 1 (starting at rs13480828), was not susceptible, thus defining a 1.0 Mb critical region that was unique to Line 1. Bioinformatic approaches identified 45 human orthologs within the unique Line 1 susceptibility region, the majority syntenic to human Ch12. Applying an epilepsy network analysis of known and suspected excitability genes and examination of interstrain genomic and brain expression differences revealed novel candidates within the region. These include Stat2, which plays a role in hippocampal GABA receptor expression after status epilepticus, and novel candidates Pan2, Cdk2, Gls2 and Cs, which are involved in neural cell differentiation, cellular remodeling and embryonic development. Our strategy may facilitate discovery of novel human epilepsy genes.
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Affiliation(s)
- M R Winawer
- Department of Neurology; G.H. Sergievsky Center, Columbia University, New York, NY, USA
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Cooper DN, Krawczak M, Polychronakos C, Tyler-Smith C, Kehrer-Sawatzki H. Where genotype is not predictive of phenotype: towards an understanding of the molecular basis of reduced penetrance in human inherited disease. Hum Genet 2013; 132:1077-130. [PMID: 23820649 PMCID: PMC3778950 DOI: 10.1007/s00439-013-1331-2] [Citation(s) in RCA: 417] [Impact Index Per Article: 37.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2013] [Accepted: 06/15/2013] [Indexed: 02/06/2023]
Abstract
Some individuals with a particular disease-causing mutation or genotype fail to express most if not all features of the disease in question, a phenomenon that is known as 'reduced (or incomplete) penetrance'. Reduced penetrance is not uncommon; indeed, there are many known examples of 'disease-causing mutations' that fail to cause disease in at least a proportion of the individuals who carry them. Reduced penetrance may therefore explain not only why genetic diseases are occasionally transmitted through unaffected parents, but also why healthy individuals can harbour quite large numbers of potentially disadvantageous variants in their genomes without suffering any obvious ill effects. Reduced penetrance can be a function of the specific mutation(s) involved or of allele dosage. It may also result from differential allelic expression, copy number variation or the modulating influence of additional genetic variants in cis or in trans. The penetrance of some pathogenic genotypes is known to be age- and/or sex-dependent. Variable penetrance may also reflect the action of unlinked modifier genes, epigenetic changes or environmental factors. At least in some cases, complete penetrance appears to require the presence of one or more genetic variants at other loci. In this review, we summarize the evidence for reduced penetrance being a widespread phenomenon in human genetics and explore some of the molecular mechanisms that may help to explain this enigmatic characteristic of human inherited disease.
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Affiliation(s)
- David N. Cooper
- Institute of Medical Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff, CF14 4XN UK
| | - Michael Krawczak
- Institute of Medical Informatics and Statistics, Christian-Albrechts University, 24105 Kiel, Germany
| | | | - Chris Tyler-Smith
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, CB10 1SA UK
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Lal D, Trucks H, Møller RS, Hjalgrim H, Koeleman BPC, de Kovel CGF, Visscher F, Weber YG, Lerche H, Becker F, Schankin CJ, Neubauer BA, Surges R, Kunz WS, Zimprich F, Franke A, Illig T, Ried JS, Leu C, Nürnberg P, Sander T. Rare exonic deletions of the RBFOX1 gene increase risk of idiopathic generalized epilepsy. Epilepsia 2013; 54:265-71. [PMID: 23350840 DOI: 10.1111/epi.12084] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/21/2012] [Indexed: 01/13/2023]
Abstract
PURPOSE Structural variations disrupting the gene encoding the neuron-specific splicing regulator RBFOX1 have been reported in three patients exhibiting epilepsy in comorbidity with other neuropsychiatric disorders. Consistently, the Rbfox1 knockout mouse model showed an increased susceptibility of seizures. The present candidate gene study tested whether exon-disrupting deletions of RBFOX1 increase the risk of idiopathic generalized epilepsies (IGEs), representing the largest group of genetically determined epilepsies. METHODS Screening of microdeletions (size: >40 kb, coverage >20 markers) affecting the genomic sequence of the RBFOX1 gene was carried out by high-resolution single-nucleotide polymorphism (SNP) arrays in 1,408 European patients with idiopathic generalized epilepsy (IGE) and 2,256 population controls. Validation of RBFOX1 deletions and familial segregation analysis were performed by quantitative polymerase chain reaction (qPCR). KEY FINDINGS We detected five exon-disrupting RBFOX1 deletions in the IGE patients, whereas none was observed in the controls (p = 0.008, Fisher's exact test). The size of the exonic deletions ranged from 68 to 896 kb and affected the untranslated 5'-terminal RBFOX1 exons. Segregation analysis in four families indicated that the deletions were inherited, display incomplete penetrance, and heterogeneous cosegregation patterns with IGE. SIGNIFICANCE Rare deletions affecting the untranslated 5'-terminal RBFOX1 exons increase risk of common IGE syndromes. Variable expressivity, incomplete penetrance, and heterogeneous cosegregation patterns suggest that RBFOX1 deletions act as susceptibility factor in a genetically complex etiology, where heterogeneous combinations of genetic factors determine the disease phenotype.
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Affiliation(s)
- Dennis Lal
- Cologne Center for Genomics, University of Cologne, Cologne, Germany
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Møller RS, Weber YG, Klitten LL, Trucks H, Muhle H, Kunz WS, Mefford HC, Franke A, Kautza M, Wolf P, Dennig D, Schreiber S, Rückert IM, Wichmann HE, Ernst JP, Schurmann C, Grabe HJ, Tommerup N, Stephani U, Lerche H, Hjalgrim H, Helbig I, Sander T. Exon-disrupting deletions of NRXN1 in idiopathic generalized epilepsy. Epilepsia 2013; 54:256-64. [PMID: 23294455 DOI: 10.1111/epi.12078] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/14/2012] [Indexed: 11/27/2022]
Abstract
PURPOSE Neurexins are neuronal adhesion molecules located in the presynaptic terminal, where they interact with postsynaptic neuroligins to form a transsynaptic complex required for efficient neurotransmission in the brain. Recently, deletions and point mutations of the neurexin 1 (NRXN1) gene have been associated with a broad spectrum of neuropsychiatric disorders. This study aimed to investigate if NRXN1 deletions also increase the risk of idiopathic generalized epilepsies (IGEs). METHODS We screened for deletions involving the NRXN1 gene in 1,569 patients with IGE and 6,201 controls using high-density oligonucleotide microarrays. KEY FINDINGS We identified exon-disrupting deletions of NRXN1 in 5 of 1,569 patients with IGE and 2 of 6,201 control individuals (p = 0.0049; odds ratio (OR) 9.91, 95% confidence interval (CI) 1.92-51.12). A complex familial segregation pattern in the IGE families was observed, suggesting that heterozygous NRXN1 deletions are susceptibility variants. Intriguingly, we identified a second large copy number variant in three of five index patients, supporting an involvement of heterogeneous susceptibility alleles in the etiology of IGE. SIGNIFICANCE We conclude that exon-disrupting deletions of NRXN1 represent a genetic risk factor in the genetically complex predisposition of common IGE syndromes.
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Familial cosegregation of rare genetic variants with disease in complex disorders. Eur J Hum Genet 2012; 21:444-50. [PMID: 23010752 DOI: 10.1038/ejhg.2012.194] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Family-based designs are increasingly being used for identification of rare variants in complex disorders. This paper addresses two questions related to the utility of these designs. First, under what circumstances are rare disease-related variants expected to cosegregate with disease in families? Second, under what circumstances is a disease-variant association expected to be greater in studies restricted to familial cases than in studies of unselected cases? To investigate these questions, we developed a probability model of disease causation involving two loci. To address cosegregation, we examined the probability that an affected first-degree relative of a variant-carrying proband would also carry the variant. We find that this probability increases with increasing odds ratio (OR) for the variant, but declines with increasing sibling recurrence risk ratio (λs). For example, under reasonable assumptions, the 15q13.3 microdeletion in idiopathic generalized epilepsy, with an OR estimate of 68 in large case-control studies, is expected to be present in >95% of affected first-degree relatives of variant-carrying probands. However, for a variant with OR=5, the probability an affected relative has the variant ranges from 82% (when λs=2) to 58% (when λs=50). We also find that restriction of a study to familial cases does not necessarily increase a rare variant's association with disease, especially if λs is high and the variant contributes little to overall disease familial aggregation. These findings provide guidance for the design of family-based studies of rare variants in complex disorders.
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Reid CA, Phillips AM, Petrou S. HCN channelopathies: pathophysiology in genetic epilepsy and therapeutic implications. Br J Pharmacol 2012; 165:49-56. [PMID: 21615728 DOI: 10.1111/j.1476-5381.2011.01507.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Hyperpolarization-activated cyclic nucleotide-gated channels (HCN) can act as pacemakers in the brain making them strong candidates for driving aberrant hypersynchronous network activity seen in epilepsy. Transcriptional changes in HCN channels occur in several animal models of epilepsy. However, only recently have genetic studies demonstrated sequence variation in HCN1 and HCN2 genes associated with human epilepsy. These include a triple proline deletion in HCN2 that increases channel function and occurs more often in patients with febrile seizure syndromes. Other HCNx gene variants have been described in idiopathic generalized epilepsy although the functional consequence of these remains unclear. In this review we explore potential cellular and network mechanisms involving HCN channels in the genetic epilepsies. We suggest how new genetic sequencing technology, medium-throughput functional assays and the ability to develop syndrome-specific animal models will provide a more comprehensive understanding of how I(h) contributes to pathogenic mechanisms underlying human genetic epilepsy. We also discuss what is known about the pharmacological manipulation of HCN channels in the context of epilepsy and how this may help future efforts in developing HCN-channel-based therapy.
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Affiliation(s)
- Christopher A Reid
- Florey Neuroscience Institute and The Centre for Neuroscience, The University of Melbourne, Parkville, Victoria, Australia.
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The Role of Seizure-Related SEZ6 as a Susceptibility Gene in Febrile Seizures. Neurol Res Int 2011; 2011:917565. [PMID: 21785725 PMCID: PMC3139179 DOI: 10.1155/2011/917565] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2011] [Revised: 04/29/2011] [Accepted: 05/19/2011] [Indexed: 11/26/2022] Open
Abstract
Sixty cases of febrile seizures from a Chinese cohort had previously been reported with a strong association between variants in the seizure-related (SEZ) 6 gene and febrile seizures. They found a striking lack of genetic variation in their controls. We found genetic variation in SEZ6 at similar levels at the same DNA sequence positions in our 94 febrile seizure cases as in our 96 unaffected controls. Two of our febrile seizure cases carried rare variants predicted to have damaging consequences. Combined with some of the variants from the Chinese cohort, these data are compatible with a role for SEZ6 as a susceptibility gene for febrile seizures. However, the polygenic determinants underlying most cases of febrile seizures with complex inheritance remain to be determined.
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Reid CA, Jackson GD, Berkovic SF, Petrou S. New therapeutic opportunities in epilepsy: A genetic perspective. Pharmacol Ther 2010; 128:274-80. [DOI: 10.1016/j.pharmthera.2010.07.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2010] [Accepted: 07/02/2010] [Indexed: 12/19/2022]
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Abstract
Epilepsy is one of the most common neurological disorders, with a prevalence of 1% and lifetime incidence of 3%. There are numerous epilepsy syndromes, most of which are considered to be genetic epilepsies. Despite the discovery of more than 20 genes for epilepsy to date, much of the genetic contribution to epilepsy is not yet known. Copy number variants have been established as an important source of mutation in other complex brain disorders, including intellectual disability, autism and schizophrenia. Recent advances in technology now facilitate genome-wide searches for copy number variants and are beginning to be applied to epilepsy. Here, we discuss what is currently known about the contribution of copy number variants to epilepsy, and how that knowledge is redefining classification of clinical and genetic syndromes.
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Dibbens LM, Reid CA, Hodgson B, Thomas EA, Phillips AM, Gazina E, Cromer BA, Clarke AL, Baram TZ, Scheffer IE, Berkovic SF, Petrou S. Augmented currents of an HCN2 variant in patients with febrile seizure syndromes. Ann Neurol 2010; 67:542-6. [PMID: 20437590 DOI: 10.1002/ana.21909] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The genetic architecture of common epilepsies is largely unknown. HCNs are excellent epilepsy candidate genes because of their fundamental neurophysiological roles. Screening in subjects with febrile seizures and genetic epilepsy with febrile seizures plus revealed that 2.4% carried a common triple proline deletion (delPPP) in HCN2 that was seen in only 0.2% of blood bank controls. Currents generated by mutant HCN2 channels were approximately 35% larger than those of controls; an effect revealed using automated electrophysiology and an appropriately powered sample size. This is the first association of HCN2 and familial epilepsy, demonstrating gain of function of HCN2 current as a potential contributor to polygenic epilepsy.
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Affiliation(s)
- Leanne M Dibbens
- SA Pathology at the Women's and Children's Hospital, North Adelaide, South Australia, Australia
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Ottman R, Hirose S, Jain S, Lerche H, Lopes-Cendes I, Noebels JL, Serratosa J, Zara F, Scheffer IE. Genetic testing in the epilepsies--report of the ILAE Genetics Commission. Epilepsia 2010; 51:655-70. [PMID: 20100225 DOI: 10.1111/j.1528-1167.2009.02429.x] [Citation(s) in RCA: 130] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
In this report, the International League Against Epilepsy (ILAE) Genetics Commission discusses essential issues to be considered with regard to clinical genetic testing in the epilepsies. Genetic research on the epilepsies has led to the identification of more than 20 genes with a major effect on susceptibility to idiopathic epilepsies. The most important potential clinical application of these discoveries is genetic testing: the use of genetic information, either to clarify the diagnosis in people already known or suspected to have epilepsy (diagnostic testing), or to predict onset of epilepsy in people at risk because of a family history (predictive testing). Although genetic testing has many potential benefits, it also has potential harms, and assessment of these potential benefits and harms in particular situations is complex. Moreover, many treating clinicians are unfamiliar with the types of tests available, how to access them, how to decide whether they should be offered, and what measures should be used to maximize benefit and minimize harm to their patients. Because the field is moving rapidly, with new information emerging practically every day, we present a framework for considering the clinical utility of genetic testing that can be applied to many different syndromes and clinical contexts. Given the current state of knowledge, genetic testing has high clinical utility in few clinical contexts, but in some of these it carries implications for daily clinical practice.
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Affiliation(s)
- Ruth Ottman
- G. H. Sergievsky Center and Department of Epidemiology, Columbia University, New York, NY, USA.
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Frankel WN. Genetics of complex neurological disease: challenges and opportunities for modeling epilepsy in mice and rats. Trends Genet 2009; 25:361-7. [PMID: 19665252 DOI: 10.1016/j.tig.2009.07.001] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2009] [Revised: 06/29/2009] [Accepted: 07/02/2009] [Indexed: 11/19/2022]
Abstract
Currently, approximately 20 genetic variants are known to cause Mendelian forms of human epilepsy, leaving a vast heritability undefined. Rodent models for genetically complex epilepsy have been studied for many years, but only recently have strong candidate genes emerged, including Cacna1 g in the GAERS rat model of absence epilepsy and Kcnj10 in the low seizure threshold of DBA/2 mice. In parallel, a growing number of mouse mutations studied on multiple strain backgrounds reveal the impact of genetic modifiers on seizure severity, incidence or form--perhaps mimicking the complexity seen in humans. The field of experimental genetics in rodents is poised to study discrete epilepsy mutations on a diverse choice of strain backgrounds to develop better models and identify modifiers. But, it must find the right balance between embracing the strain diversity available, with the ability to detect and characterize genetic effects. Using alternative strain backgrounds when studying epilepsy mutations will enhance the modeling of epilepsy as a complex genetic disease.
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Affiliation(s)
- Wayne N Frankel
- The Jackson Laboratory, 600 Main Street, Bar Harbor, ME 04609, USA.
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Dibbens LM, Mullen S, Helbig I, Mefford HC, Bayly MA, Bellows S, Leu C, Trucks H, Obermeier T, Wittig M, Franke A, Caglayan H, Yapici Z, Sander T, Eichler EE, Scheffer IE, Mulley JC, Berkovic SF. Familial and sporadic 15q13.3 microdeletions in idiopathic generalized epilepsy: precedent for disorders with complex inheritance. Hum Mol Genet 2009; 18:3626-31. [PMID: 19592580 DOI: 10.1093/hmg/ddp311] [Citation(s) in RCA: 167] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Microdeletion at chromosomal position 15q13.3 has been described in intellectual disability, autism spectrum disorders, schizophrenia and recently in idiopathic generalized epilepsy (IGE). Using independent IGE cohorts, we first aimed to confirm the association of 15q13.3 deletions and IGE. We then set out to determine the relative occurrence of sporadic and familial cases and to examine the likelihood of having seizures for individuals with the microdeletion in familial cases. The 15q13.3 microdeletion was identified in 7 of 539 (1.3%) unrelated cases of IGE using quantitative PCR or SNP arrays and confirmed by array comparative genomic hybridization analysis using probes specific to the 15q13.3 region. The inheritance of this lesion was tracked using family studies. Of the seven microdeletions identified in probands, three were de novo, two were transmitted from an unaffected parent and in two cases the parents were unavailable. Non-penetrance of the microdeletion was identified in 4/7 pedigrees and three pedigrees included other family members with IGE who lacked the 15q13.3 deletion. The odds ratio is 68 (95% confidence interval 29-181), indicating a pathogenic lesion predisposing to epilepsy with complex inheritance and incomplete penetrance for the IGE component of the phenotype in multiplex families.
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Affiliation(s)
- Leanne M Dibbens
- Epilepsy Research Program, SA Pathology at Women's and Children's Hospital, North Adelaide, South Australia 5006, Australia.
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Mulley JC, Dibbens LM. Chipping away at the common epilepsies with complex genetics: the 15q13.3 microdeletion shows the way. Genome Med 2009; 1:33. [PMID: 19341504 PMCID: PMC2664944 DOI: 10.1186/gm33] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
The idiopathic epilepsies are genetically heterogeneous with more than 50 clinical classifications. They are characterized by episodic seizures arising from erratic neuronal discharge in susceptible individuals. The most common predisposing genetic cause is the recently discovered chromosome 15q13.3 microdeletion. Other disorders previously attributed to the same lesion include autism, intellectual disability and schizophrenia. This phenotypic spectrum is most easily imagined as a contiguous gene syndrome with idiopathic generalized epilepsy as the most common clinical manifestation. Expressivity of the microdeletion in carriers is too variable for antenatal prediction of phenotype to be possible; however, when it is detected in living affected cases, it can be taken as the major predisposing cause for the observed phenotype. The discovery of this small 15q13.3 lesion barely scratches the surface that conceals what we ultimately need to know about the molecular genetic mechanisms behind the common epilepsies with complex genetics, but it provides valuable insight into how to proceed toward that goal.
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Affiliation(s)
- John C Mulley
- Epilepsy Research Program, Genetics and Molecular Pathology, SA Pathology at the Women's and Children's Hospital, 72 King William Road, North Adelaide, SA 5006, Australia
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Dibbens LM, Harkin LA, Richards M, Hodgson BL, Clarke AL, Petrou S, Scheffer IE, Berkovic SF, Mulley JC. The role of neuronal GABA(A) receptor subunit mutations in idiopathic generalized epilepsies. Neurosci Lett 2009; 453:162-5. [PMID: 19429026 DOI: 10.1016/j.neulet.2009.02.038] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2008] [Revised: 02/04/2009] [Accepted: 02/17/2009] [Indexed: 10/21/2022]
Abstract
Rare GABA(A) receptor gamma2 and alpha1 subunit mutations of pathogenic effect have been described segregating in families with "monogenic" epilepsies. We now report globally on the genetic variation contained within all 16 neuronal GABA(A) receptor subunit genes from the one patient cohort. The cohort consists of GEFS(+), FS, and IGE subgroups as either sporadic cases or index cases from small families, with one index case from one large IGE family. The rarity of mutations and coding variation in general across all of the subunits suggests a low tolerance for mutations affecting GABA mediated neuronal inhibition. Characterization of the broader channelopathy load associated with susceptibility to these common epilepsies mostly with complex genetics will need to be expanded beyond the family of GABA(A) receptor subunits to all families of neuronal ion channels and their interacting molecules by systematic mutation detection associated with functional investigation of their naturally occurring genetic variations.
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Affiliation(s)
- L M Dibbens
- Epilepsy Research Program, SA Pathology at Women's and Children's Hospital, North Adelaide, South Australia, Australia.
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Mulley JC. Forty Years From Markers to Genes. Twin Res Hum Genet 2008; 11:368-83. [DOI: 10.1375/twin.11.4.368] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
AbstractThere have been incredible advances made in human genetics over the past 40 years. I have set out in the next few pages to describe just some of these changes and to illustrate how they unfolded through my own experiences.
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Heron SE, Khosravani H, Varela D, Bladen C, Williams TC, Newman MR, Scheffer IE, Berkovic SF, Mulley JC, Zamponi GW. Extended spectrum of idiopathic generalized epilepsies associated withCACNA1Hfunctional variants. Ann Neurol 2007; 62:560-8. [PMID: 17696120 DOI: 10.1002/ana.21169] [Citation(s) in RCA: 152] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVE The relationship between genetic variation in the T-type calcium channel gene CACNA1H and childhood absence epilepsy is well established. The purpose of this study was to investigate the range of epilepsy syndromes for which CACNA1H variants may contribute to the genetic susceptibility architecture and determine the electrophysiological effects of these variants in relation to proposed mechanisms underlying seizures. METHODS Exons 3 to 35 of CACNA1H were screened for variants in 240 epilepsy patients (167 unrelated) and 95 control subjects by single-stranded conformation analysis followed by direct sequencing. Cascade testing of families was done by sequencing or single-stranded conformation analysis. Selected variants were introduced into the CACNA1H protein by site-directed mutagenesis. Constructs were transiently transfected into human embryo kidney cells, and electrophysiological data were acquired. RESULTS More than 100 variants were detected, including 19 novel variants leading to amino acid changes in subjects with phenotypes including childhood absence, juvenile absence, juvenile myoclonic and myoclonic astatic epilepsies, as well as febrile seizures and temporal lobe epilepsy. Electrophysiological analysis of 11 variants showed that 9 altered channel properties, generally in ways that would be predicted to increase calcium current. INTERPRETATION Variants in CACNA1H that alter channel properties are present in patients with various generalized epilepsy syndromes. We propose that these variants contribute to an individual's susceptibility to epilepsy but are not sufficient to cause epilepsy on their own. The genetic architecture is dominated by rare functional variants; therefore, CACNA1H would not be easily identified as a susceptibility gene by a genome-wide case-control study seeking a statistical association.
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Affiliation(s)
- Sarah E Heron
- Department of Genetic Medicine, Women's and Children's Hospital, North Adelaide South Australia, Australia.
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Heron SE, Scheffer IE, Berkovic SF, Dibbens LM, Mulley JC. Channelopathies in idiopathic epilepsy. Neurotherapeutics 2007; 4:295-304. [PMID: 17395140 DOI: 10.1016/j.nurt.2007.01.009] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Approximately 70% of all patients with epilepsy lack an obvious extraneous cause and are presumed to have a predominantly genetic basis. Both familial and de novo mutations in neuronal voltage-gated and ligand-gated ion channel subunit genes have been identified in autosomal dominant epilepsies. However, patients with dominant familial mutations are rare and the majority of idiopathic epilepsy is likely to be the result of polygenic susceptibility alleles (complex epilepsy). Data on the identity of the genes involved in complex epilepsy is currently sparse but again points to neuronal ion channels. The number of genes and gene families associated with epilepsy is rapidly increasing and this increase is likely to escalate over the coming years with advances in mutation detection technologies. The genetic heterogeneity underlying idiopathic epilepsy presents challenges for the rational selection of therapies targeting particular ion channels. Too little is currently known about the genetic architecture of the epilepsies, and genetic testing for the known epilepsy genes remains costly. Pharmacogenetic studies have yet to explain why 30% of patients do not respond to the usual antiepileptic drugs. Despite this, the recognition that the idiopathic epilepsies are a group of channelopathies has, to a limited extent, explained the therapeutic action of the common antiepileptic drugs and has assisted clinical diagnosis of some epilepsy syndromes.
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Affiliation(s)
- Sarah E Heron
- Department of Genetic Medicine, Women's and Children's Hospital, North Adelaide, South Australia 5006.
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