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Chang YT, Hong SY, Lin WD, Lin CH, Lin SS, Tsai FJ, Chou IC. Genetic Testing in Children with Developmental and Epileptic Encephalopathies: A Review of Advances in Epilepsy Genomics. CHILDREN 2023; 10:children10030556. [PMID: 36980114 PMCID: PMC10047509 DOI: 10.3390/children10030556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Revised: 03/11/2023] [Accepted: 03/13/2023] [Indexed: 03/17/2023]
Abstract
Advances in disease-related gene discovery have led to tremendous innovations in the field of epilepsy genetics. Identification of genetic mutations that cause epileptic encephalopathies has opened new avenues for the development of targeted therapies. Clinical testing using extensive gene panels, exomes, and genomes is currently accessible and has resulted in higher rates of diagnosis and better comprehension of the disease mechanisms underlying the condition. Children with developmental disabilities have a higher risk of developing epilepsy. As our understanding of the mechanisms underlying encephalopathies and epilepsies improves, there may be greater potential to develop innovative therapies tailored to an individual’s genotype. This article provides an overview of the significant progress in epilepsy genomics in recent years, with a focus on developmental and epileptic encephalopathies in children. The aim of this review is to enhance comprehension of the clinical utilization of genetic testing in this particular patient population. The development of effective and precise therapeutic strategies for epileptic encephalopathies may be facilitated by a comprehensive understanding of their molecular pathogenesis.
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Affiliation(s)
- Yu-Tzu Chang
- School of Post Baccalaureate Chinese Medicine, China Medical University, Taichung 40447, Taiwan; (Y.-T.C.)
- Division of Pediatric Neurology, China Medical University Children’s Hospital, Taichung 40447, Taiwan
| | - Syuan-Yu Hong
- Division of Pediatric Neurology, China Medical University Children’s Hospital, Taichung 40447, Taiwan
- Department of Medicine, School of Medicine, China Medical University, Taichung 40447, Taiwan
- Graduate Institute of Biomedical Sciences, China Medical University, Taichung 40447, Taiwan
| | - Wei-De Lin
- School of Post Baccalaureate Chinese Medicine, China Medical University, Taichung 40447, Taiwan; (Y.-T.C.)
- Department of Medical Research, China Medical University Hospital, Taichung 40447, Taiwan
| | - Chien-Heng Lin
- Division of Pediatric Pulmonology, China Medical University Children’s Hospital, Taichung 40447, Taiwan
- Department of Biomedical Imaging and Radiological Science, College of Medicine, China Medial University, Taichung 40447, Taiwan
| | - Sheng-Shing Lin
- School of Post Baccalaureate Chinese Medicine, China Medical University, Taichung 40447, Taiwan; (Y.-T.C.)
- Division of Pediatric Neurology, China Medical University Children’s Hospital, Taichung 40447, Taiwan
| | - Fuu-Jen Tsai
- Department of Medical Research, China Medical University Hospital, Taichung 40447, Taiwan
- Division of Genetics and Metabolism, China Medical University Children’s Hospital, Taichung 40447, Taiwan
- Department of Medical Genetics, China Medical University Hospital, Taichung 40447, Taiwan
- School of Chinese Medicine, China Medical University, Taichung 40447, Taiwan
- Department of Medical Laboratory Science and Biotechnology, Asia University, Taichung 40447, Taiwan
| | - I-Ching Chou
- Division of Pediatric Neurology, China Medical University Children’s Hospital, Taichung 40447, Taiwan
- Graduate Institute of Integrated Medicine, China Medical University, Taichung 40447, Taiwan
- Correspondence: ; Tel.: +886-4-22052121
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Badshah N, Mattison KA, Ahmad S, Chopra P, Johnston HR, Ahmad S, Khan SH, Sarwar MT, Cutler DJ, Taylor M, Vadlamani G, Zwick ME, Escayg A. Novel Missense CNTNAP2 Variant Identified in Two Consanguineous Pakistani Families With Developmental Delay, Epilepsy, Intellectual Disability, and Aggressive Behavior. Front Neurol 2022; 13:918022. [PMID: 35911904 PMCID: PMC9329621 DOI: 10.3389/fneur.2022.918022] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Accepted: 06/13/2022] [Indexed: 11/13/2022] Open
Abstract
We report the genetic analysis of two consanguineous pedigrees of Pakistani ancestry in which two siblings in each family exhibited developmental delay, epilepsy, intellectual disability and aggressive behavior. Whole-genome sequencing was performed in Family 1, and we identified ~80,000 variants located in regions of homozygosity. Of these, 615 variants had a minor allele frequency ≤ 0.001, and 21 variants had CADD scores ≥ 15. Four homozygous exonic variants were identified in both affected siblings: PDZD7 (c.1348_1350delGAG, p.Glu450del), ALG6 (c.1033G>C, p.Glu345Gln), RBM20 (c.1587C>G, p.Ser529Arg), and CNTNAP2 (c.785G>A, p.Gly228Arg). Sanger sequencing revealed co-segregation of the PDZD7, RBM20, and CNTNAP2 variants with disease in Family 1. Pathogenic variants in PDZD7 and RBM20 are associated with autosomal recessive non-syndromic hearing loss and autosomal dominant dilated cardiomyopathy, respectively, suggesting that these variants are unlikely likely to contribute to the clinical presentation. Gene panel analysis was performed on the two affected siblings in Family 2, and they were found to also be homozygous for the p.Gly228Arg CNTNAP2 variant. Together these families provide a LOD score 2.9 toward p.Gly228Arg CNTNAP2 being a completely penetrant recessive cause of this disease. The clinical presentation of the affected siblings in both families is also consistent with previous reports from individuals with homozygous CNTNAP2 variants where at least one allele was a nonsense variant, frameshift or small deletion. Our data suggests that homozygous CNTNAP2 missense variants can also contribute to disease, thereby expanding the genetic landscape of CNTNAP2 dysfunction.
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Affiliation(s)
- Noor Badshah
- Institute of Biotechnology and Genetic Engineering, University of Agriculture Peshawar, Peshawar, Pakistan
- Department of Human Genetics, Emory University, Atlanta, GA, United States
| | - Kari A. Mattison
- Department of Human Genetics, Emory University, Atlanta, GA, United States
- Genetics and Molecular Biology Graduate Program, Graduate Division of Biological and Biomedical Sciences, Laney Graduate School, Emory University, Atlanta, GA, United States
| | - Sohail Ahmad
- Institute of Biotechnology and Genetic Engineering, University of Agriculture Peshawar, Peshawar, Pakistan
| | - Pankaj Chopra
- Department of Human Genetics, Emory University, Atlanta, GA, United States
| | | | - Shakoor Ahmad
- Department of Animal Health, University of Agriculture Peshawar, Peshawar, Pakistan
| | - Sher Hayat Khan
- Institute of Biotechnology and Genetic Engineering, University of Agriculture Peshawar, Peshawar, Pakistan
| | - Muhammad Tahir Sarwar
- Department of Molecular Biology and Genetics, Institute of Basic Medical Sciences, Khyber Medical University, Peshawar, Pakistan
| | - David J. Cutler
- Department of Human Genetics, Emory University, Atlanta, GA, United States
| | - Micheal Taylor
- Department of Pediatric Neurology, Leeds Teaching Hospital NHS Trust, Leeds, United Kingdom
| | - Gayatri Vadlamani
- Department of Pediatric Neurology, Leeds Teaching Hospital NHS Trust, Leeds, United Kingdom
| | - Michael E. Zwick
- Department of Human Genetics, Emory University, Atlanta, GA, United States
| | - Andrew Escayg
- Department of Human Genetics, Emory University, Atlanta, GA, United States
- *Correspondence: Andrew Escayg
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Chen WL, Mefford HC. Diagnostic Considerations in the Epilepsies-Testing Strategies, Test Type Advantages, and Limitations. Neurotherapeutics 2021; 18:1468-1477. [PMID: 34532824 PMCID: PMC8608977 DOI: 10.1007/s13311-021-01121-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/04/2021] [Indexed: 02/04/2023] Open
Abstract
The role of genetics in epilepsy has been recognized for a long time. Over the past decade, genome-wide technologies have identified numerous genes and variants associated with epilepsy. In the clinical setting, a myriad of genetic testing options are available, and a subset of specific genetic diagnoses have management implications. Furthermore, genetic testing can be a dynamic process. As a result, fundamental knowledge about genetics and genomics has become essential for all specialists. Here, we review current knowledge of the genetic contribution to various types of epilepsy, provide an overview of types of genetic variants, and discuss genetic testing options and their diagnostic yield. We also consider advantages and limitations of testing approaches.
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Affiliation(s)
- Wei-Liang Chen
- Department of Pediatrics, Division of Genetic Medicine, University of Washington and Seattle Children's Hospital, Seattle, WA, 98105, USA
| | - Heather C Mefford
- Department of Pediatrics, Division of Genetic Medicine, University of Washington and Seattle Children's Hospital, Seattle, WA, 98105, USA.
- Current Location: Center for Pediatric Neurological Disease Research, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA.
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Abstract
Developmental and epileptic encephalopathies (DEEs) are a group of severe, early onset epilepsies characterized by refractory seizures, developmental delay or regression associated with ongoing epileptic activity, and generally poor prognosis. DEE is genetically and phenotypically heterogeneous, and there is a plethora of genetic testing options to investigate the rapidly growing list of epilepsy genes. However, more than 50% of patients with DEE remain without a genetic diagnosis despite state-of-the-art genetic testing. In this review, we discuss the major advances in epilepsy genomics that have surfaced in recent years. The goal of this review is to reach a larger audience and build a better understanding of pathogenesis and genetic testing options in DEE.
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Affiliation(s)
- Malavika Hebbar
- Division of Genetic Medicine, Department of Pediatrics, University of Washington, Seattle, WA, 98105, USA
| | - Heather C Mefford
- Division of Genetic Medicine, Department of Pediatrics, University of Washington, Seattle, WA, 98105, USA
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A tiered strategy for investigating status epilepticus. Seizure 2020; 75:165-173. [DOI: 10.1016/j.seizure.2019.10.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Revised: 10/07/2019] [Accepted: 10/08/2019] [Indexed: 01/03/2023] Open
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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: 29] [Impact Index Per Article: 5.8] [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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