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Musto E, Liao VWY, Johannesen KM, Fenger CD, Lederer D, Kothur K, Fisk K, Bennetts B, Vrielynck P, Delaby D, Ceulemans B, Weckhuysen S, Sparber P, Bouman A, Ardern-Holmes S, Troedson C, Battaglia DI, Goel H, Feyma T, Bakhtiari S, Tjoa L, Boxill M, Demina N, Shchagina O, Dadali E, Kruer M, Cantalupo G, Contaldo I, Polster T, Isidor B, Bova SM, Fazeli W, Wouters L, Miranda MJ, Darra F, Pede E, Le Duc D, Jamra RA, Küry S, Proietti J, McSweeney N, Brokamp E, Andrews PI, Gouray Garcia M, Chebib M, Møller RS, Ahring PK, Gardella E. GABRA1-Related Disorders: From Genetic to Functional Pathways. Ann Neurol 2023; 95:27-41. [PMID: 37606373 DOI: 10.1002/ana.26774] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Revised: 08/18/2023] [Accepted: 08/18/2023] [Indexed: 08/23/2023]
Abstract
OBJECTIVE Variants in GABRA1 have been associated with a broad epilepsy spectrum, ranging from genetic generalized epilepsies to developmental and epileptic encephalopathies. However, our understanding of what determines the phenotype severity and best treatment options remains inadequate. We therefore aimed to analyze the electroclinical features and the functional effects of GABRA1 variants to establish genotype-phenotype correlations. METHODS Genetic and electroclinical data of 27 individuals (22 unrelated and 2 families) harboring 20 different GABRA1 variants were collected and accompanied by functional analysis of 19 variants. RESULTS Individuals in this cohort could be assigned into different clinical subgroups based on the functional effect of their variant and its structural position within the GABRA1 subunit. A homogenous phenotype with mild cognitive impairment and infantile onset epilepsy (focal seizures, fever sensitivity, and electroencephalographic posterior epileptiform discharges) was described for variants in the extracellular domain and the small transmembrane loops. These variants displayed loss-of-function (LoF) effects, and the patients generally had a favorable outcome. A more severe phenotype was associated with variants in the pore-forming transmembrane helices. These variants displayed either gain-of-function (GoF) or LoF effects. GoF variants were associated with severe early onset neurodevelopmental disorders, including early infantile developmental and epileptic encephalopathy. INTERPRETATION Our data expand the genetic and phenotypic spectrum of GABRA1 epilepsies and permit delineation of specific subphenotypes for LoF and GoF variants, through the heterogeneity of phenotypes and variants. Generally, variants in the transmembrane helices cause more severe phenotypes, in particular GoF variants. These findings establish the basis for a better understanding of the pathomechanism and a precision medicine approach in GABRA1-related disorders. Further studies in larger populations are needed to provide a conclusive genotype-phenotype correlation. ANN NEUROL 2023.
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Affiliation(s)
- Elisa Musto
- Department of Epilepsy Genetics and Personalized Medicine, Danish Epilepsy Center, Dianalund, Denmark
- Pediatric Neurology, Department of Woman and Child Health and Public Health, Child Health Area, Catholic University UCSC, Rome, Italy
- Epilepsy and Movement Disorder Neurology, Ospedale Pediatrico Bambino Gesù IRCCS, Rome, Italy
| | - Vivian W Y Liao
- Brain and Mind Centre, School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
| | - Katrine M Johannesen
- Department of Epilepsy Genetics and Personalized Medicine, Danish Epilepsy Center, Dianalund, Denmark
- Department of Genetics, University Hospital of Copenhagen, Copenhagen, Denmark
| | - Christina D Fenger
- Department of Epilepsy Genetics and Personalized Medicine, Danish Epilepsy Center, Dianalund, Denmark
- Amplexa Genetics, Odense, Denmark
| | - Damien Lederer
- Center for Human Genetics, Institut de Pathologie et de Génétique, Gosselies, Belgium
| | - Kavitha Kothur
- Kids Neuroscience Centre, Children's Hospital at Westmead, University of Sydney, Sydney, New South Wales, Australia
| | - Katrina Fisk
- Sydney Genome Diagnostics, Western Sydney Genetics Program, Children's Hospital at Westmead, Sydney, New South Wales, Australia
| | - Bruce Bennetts
- Sydney Genome Diagnostics, Western Sydney Genetics Program, Children's Hospital at Westmead, Sydney, New South Wales, Australia
- Specialty of Genomic Medicine, Children's Hospital at Westmead Clinical School, Faculty of Medicine and Health, University of Sydney, Sydney, New South Wales, Australia
| | - Pascal Vrielynck
- Reference Center for Refractory Epilepsy, Catholic University of Louvain, William Lennox Neurological Hospital, Ottignies, Belgium
| | - Delphine Delaby
- Reference Center for Refractory Epilepsy, Catholic University of Louvain, William Lennox Neurological Hospital, Ottignies, Belgium
| | - Berten Ceulemans
- Department of Pediatric Neurology, Antwerp University Hospital, University of Antwerp, Antwerp, Belgium
| | - Sarah Weckhuysen
- Applied & Translational Neurogenomics Group, VIB-Department of Molecular Genetics, University of Antwerp, Antwerp, Belgium
- Department of Neurology, Antwerp University Hospital, Antwerp, Belgium
- Translational Neurosciences, Faculty of Medicine and Health Science, University of Antwerp, Antwerp, Belgium
| | - Peter Sparber
- Research Center for Medical Genetics Moskvorechie 1, Moscow, Russia
| | - Arjan Bouman
- Department of Clinical Genetics, Erasmus MC, University Medical Center Rotterdam, Rotterdam, the Netherlands
| | - Simone Ardern-Holmes
- Kids Neuroscience Centre, Children's Hospital at Westmead, University of Sydney, Sydney, New South Wales, Australia
- T. Y. Nelson Department of Neurology and Neurosurgery, Children's Hospital at Westmead, Westmead, New South Wales, Australia
| | - Christopher Troedson
- T. Y. Nelson Department of Neurology and Neurosurgery, Children's Hospital at Westmead, Westmead, New South Wales, Australia
| | - Domenica I Battaglia
- Pediatric Neurology, Department of Woman and Child Health and Public Health, Child Health Area, Catholic University UCSC, Rome, Italy
| | - Himanshu Goel
- Hunter Genetics, Newcastle, New South Wales, Australia
| | - Timothy Feyma
- Gillette Children's Specialty Healthcare, Saint Paul, MN, USA
| | - Somayeh Bakhtiari
- Pediatric Movement Disorders Program, Division of Pediatric Neurology, Barrow Neurological Institute, Phoenix Children's Hospital, Phoenix, AZ, USA
- Departments of Child Health, Neurology, and Cellular & Molecular Medicine and Program in Genetics, University of Arizona College of Medicine, Phoenix, AZ, USA
| | - Linda Tjoa
- Townsville University Hospital, Douglas, Queensland, Australia
| | - Martin Boxill
- Department of Pediatrics, Viborg Regional Hospital, Viborg, Denmark
| | - Nina Demina
- Research Center for Medical Genetics Moskvorechie 1, Moscow, Russia
| | - Olga Shchagina
- Research Center for Medical Genetics Moskvorechie 1, Moscow, Russia
| | - Elena Dadali
- Research Center for Medical Genetics Moskvorechie 1, Moscow, Russia
| | - Michael Kruer
- Pediatric Movement Disorders Program, Division of Pediatric Neurology, Barrow Neurological Institute, Phoenix Children's Hospital, Phoenix, AZ, USA
- Departments of Child Health, Neurology, and Cellular & Molecular Medicine and Program in Genetics, University of Arizona College of Medicine, Phoenix, AZ, USA
| | - Gaetano Cantalupo
- Child Neuropsychiatry Section, Department of Surgical Sciences, Dentistry, Gynecology and Paediatrics, University of Verona, Verona, Italy
- UOC Neuropsichiatria Infantile, Dipartimento Materno-Infantile, Azienda Ospedaliero-Universitaria Integrata (full member of the ERN EpiCare), Verona, Italy
- Center for Research on Epilepsies in Pediatric age (CREP), Verona, Italy
| | - Ilaria Contaldo
- Pediatric Neurology, Department of Woman and Child Health and Public Health, Child Health Area, Catholic University UCSC, Rome, Italy
| | - Tilman Polster
- Department of Epileptology (Krankenhaus Mara), Bielefeld University Medical School, Bielefeld, Germany
| | | | - Stefania M Bova
- Pediatric Neurology Unit, V. Buzzi Children's Hospital, Milan, Italy
| | - Walid Fazeli
- Department of Neuropediatrics, Children's Hospital, University of Bonn, Bonn, Germany
| | - Leen Wouters
- Department of Pediatrics, Ziekenhuis Oost-Limburg, Genk, Belgium
| | - Maria J Miranda
- Department of Pediatrics, Pediatric Neurology, Herlev University Hospital, Copenhagen University, Herlev, Denmark
| | - Francesca Darra
- Child Neuropsychiatry Section, Department of Surgical Sciences, Dentistry, Gynecology and Paediatrics, University of Verona, Verona, Italy
- UOC Neuropsichiatria Infantile, Dipartimento Materno-Infantile, Azienda Ospedaliero-Universitaria Integrata (full member of the ERN EpiCare), Verona, Italy
- Center for Research on Epilepsies in Pediatric age (CREP), Verona, Italy
| | - Elisa Pede
- Pediatric Neurology, Department of Woman and Child Health and Public Health, Child Health Area, Catholic University UCSC, Rome, Italy
| | - Diana Le Duc
- Department of Human Genetics, University of Leipzig Faculty of Medicine, Leipzig, Germany
| | - Rami Abou Jamra
- Department of Human Genetics, University of Leipzig Faculty of Medicine, Leipzig, Germany
| | - Sébastien Küry
- Service de Génétique Médicale, CHU Nantes, Nantes, France
- l'Institut du Thorax, INSERM, CNRS, Université de Nantes, Nantes, France
| | - Jacopo Proietti
- Child Neuropsychiatry Section, Department of Surgical Sciences, Dentistry, Gynecology and Paediatrics, University of Verona, Verona, Italy
- Irish Centre for Fetal and Neonatal Translational Research, Child Neuropsychiatry, Cork, Ireland
| | - Niamh McSweeney
- Department of Paediatrics, Cork University Hospital, Cork, Ireland
| | - Elly Brokamp
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Peter Ian Andrews
- Department of Neurology, Sydney Children's Hospital, Randwick, New South Wales, Australia
| | | | - Mary Chebib
- Brain and Mind Centre, School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
| | - Rikke S Møller
- Department of Epilepsy Genetics and Personalized Medicine, Danish Epilepsy Center, Dianalund, Denmark
- Department of Regional Health Research, Faculty of Health Sciences, University of Southern Denmark, Odense, Denmark
| | - Philip K Ahring
- Brain and Mind Centre, School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
| | - Elena Gardella
- Department of Epilepsy Genetics and Personalized Medicine, Danish Epilepsy Center, Dianalund, Denmark
- Department of Regional Health Research, Faculty of Health Sciences, University of Southern Denmark, Odense, Denmark
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Hannan S, Affandi AHB, Minere M, Jones C, Goh P, Warnes G, Popp B, Trollmann R, Nizetic D, Smart TG. Differential Coassembly of α1-GABA ARs Associated with Epileptic Encephalopathy. J Neurosci 2020; 40:5518-5530. [PMID: 32513829 PMCID: PMC7363476 DOI: 10.1523/jneurosci.2748-19.2020] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 05/05/2020] [Accepted: 05/06/2020] [Indexed: 01/18/2023] Open
Abstract
GABAA receptors (GABAARs) are profoundly important for controlling neuronal excitability. Spontaneous and familial mutations to these receptors feature prominently in excitability disorders and neurodevelopmental deficits following disruption to GABA-mediated inhibition. Recent genotyping of an individual with severe epilepsy and Williams-Beuren syndrome identified a frameshifting de novo variant in a major GABAAR gene, GABRA1 This truncated the α1 subunit between the third and fourth transmembrane domains and introduced 24 new residues forming the mature protein, α1Lys374Serfs*25 Cell surface expression of mutant murine GABAARs is severely impaired compared with WT, due to retention in the endoplasmic reticulum. Mutant receptors were differentially coexpressed with β3, but not with β2, subunits in mammalian cells. Reduced surface expression was reflected by smaller IPSCs, which may underlie the induction of seizures. The mutant does not have a dominant-negative effect on native neuronal GABAAR expression since GABA current density was unaffected in hippocampal neurons, although mutant receptors exhibited limited GABA sensitivity. To date, the underlying mechanism is unique for epileptogenic variants and involves differential β subunit expression of GABAAR populations, which profoundly affected receptor function and synaptic inhibition.SIGNIFICANCE STATEMENT GABAARs are critical for controlling neural network excitability. They are ubiquitously distributed throughout the brain, and their dysfunction underlies many neurologic disorders, especially epilepsy. Here we report the characterization of an α1-GABAAR variant that results in severe epilepsy. The underlying mechanism is structurally unusual, with the loss of part of the α1 subunit transmembrane domain and part-replacement with nonsense residues. This led to compromised and differential α1 subunit cell surface expression with β subunits resulting in severely reduced synaptic inhibition. Our study reveals that disease-inducing variants can affect GABAAR structure, and consequently subunit assembly and cell surface expression, critically impacting on the efficacy of synaptic inhibition, a property that will orchestrate the extent and duration of neuronal excitability.
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Affiliation(s)
- Saad Hannan
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, WC1E 6BT, United Kingdom
| | - Aida H B Affandi
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, WC1E 6BT, United Kingdom
| | - Marielle Minere
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, WC1E 6BT, United Kingdom
| | - Charlotte Jones
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, WC1E 6BT, United Kingdom
| | - Pollyanna Goh
- The Blizard Institute, Barts & The London School of Medicine, Queen Mary University of London, London, E1 2AT, United Kingdom
| | - Gary Warnes
- The Blizard Institute, Barts & The London School of Medicine, Queen Mary University of London, London, E1 2AT, United Kingdom
| | - Bernt Popp
- Institute of Human Genetics, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, 91054, Germany
- Institute of Human Genetics, University of Leipzig Hospitals and Clinics, Leipzig, 04103, Germany
| | - Regina Trollmann
- Department of Pediatrics, Division of Neuropediatrics, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, 91054, Germany
| | - Dean Nizetic
- The Blizard Institute, Barts & The London School of Medicine, Queen Mary University of London, London, E1 2AT, United Kingdom
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, 308232
| | - Trevor G Smart
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, WC1E 6BT, United Kingdom
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Smith HS, Swint JM, Lalani SR, Yamal JM, de Oliveira Otto MC, Castellanos S, Taylor A, Lee BH, Russell HV. Clinical Application of Genome and Exome Sequencing as a Diagnostic Tool for Pediatric Patients: a Scoping Review of the Literature. Genet Med 2018; 21:3-16. [PMID: 29760485 DOI: 10.1038/s41436-018-0024-6] [Citation(s) in RCA: 86] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Accepted: 03/20/2018] [Indexed: 12/17/2022] Open
Abstract
PURPOSE Availability of clinical genomic sequencing (CGS) has generated questions about the value of genome and exome sequencing as a diagnostic tool. Analysis of reported CGS application can inform uptake and direct further research. This scoping literature review aims to synthesize evidence on the clinical and economic impact of CGS. METHODS PubMed, Embase, and Cochrane were searched for peer-reviewed articles published between 2009 and 2017 on diagnostic CGS for infant and pediatric patients. Articles were classified according to sample size and whether economic evaluation was a primary research objective. Data on patient characteristics, clinical setting, and outcomes were extracted and narratively synthesized. RESULTS Of 171 included articles, 131 were case reports, 40 were aggregate analyses, and 4 had a primary economic evaluation aim. Diagnostic yield was the only consistently reported outcome. Median diagnostic yield in aggregate analyses was 33.2% but varied by broad clinical categories and test type. CONCLUSION Reported CGS use has rapidly increased and spans diverse clinical settings and patient phenotypes. Economic evaluations support the cost-saving potential of diagnostic CGS. Multidisciplinary implementation research, including more robust outcome measurement and economic evaluation, is needed to demonstrate clinical utility and cost-effectiveness of CGS.
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Affiliation(s)
- Hadley Stevens Smith
- Baylor College of Medicine, The University of Texas School of Public Health, Houston, Texas, USA
| | - J Michael Swint
- The University of Texas School of Public Health, The Center for Clinical Research and Evidence-Based Medicine, The University of Texas McGovern Medical School, Houston, Texas, USA
| | - Seema R Lalani
- Baylor College of Medicine, Baylor Genetics Laboratory, Houston, Texas, USA
| | - Jose-Miguel Yamal
- The University of Texas School of Public Health, Houston, Texas, USA
| | | | | | - Amy Taylor
- Texas Medical Center Library, Houston, Texas, USA
| | | | - Heidi V Russell
- Texas Children's Hospital, Baylor College of Medicine, Houston, Texas, USA
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