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Silva DB, Trinidad M, Ljungdahl A, Revalde JL, Berguig GY, Wallace W, Patrick CS, Bomba L, Arkin M, Dong S, Estrada K, Hutchinson K, LeBowitz JH, Schlessinger A, Johannesen KM, Møller RS, Giacomini KM, Froelich S, Sanders SJ, Wuster A. Haploinsufficiency underlies the neurodevelopmental consequences of SLC6A1 variants. Am J Hum Genet 2024; 111:1222-1238. [PMID: 38781976 PMCID: PMC11179425 DOI: 10.1016/j.ajhg.2024.04.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Revised: 04/26/2024] [Accepted: 04/26/2024] [Indexed: 05/25/2024] Open
Abstract
Heterozygous variants in SLC6A1, encoding the GAT-1 GABA transporter, are associated with seizures, developmental delay, and autism. The majority of affected individuals carry missense variants, many of which are recurrent germline de novo mutations, raising the possibility of gain-of-function or dominant-negative effects. To understand the functional consequences, we performed an in vitro GABA uptake assay for 213 unique variants, including 24 control variants. De novo variants consistently resulted in a decrease in GABA uptake, in keeping with haploinsufficiency underlying all neurodevelopmental phenotypes. Where present, ClinVar pathogenicity reports correlated well with GABA uptake data; the functional data can inform future reports for the remaining 72% of unscored variants. Surface localization was assessed for 86 variants; two-thirds of loss-of-function missense variants prevented GAT-1 from being present on the membrane while GAT-1 was on the surface but with reduced activity for the remaining third. Surprisingly, recurrent de novo missense variants showed moderate loss-of-function effects that reduced GABA uptake with no evidence for dominant-negative or gain-of-function effects. Using linear regression across multiple missense severity scores to extrapolate the functional data to all potential SLC6A1 missense variants, we observe an abundance of GAT-1 residues that are sensitive to substitution. The extent of this missense vulnerability accounts for the clinically observed missense enrichment; overlap with hypermutable CpG sites accounts for the recurrent missense variants. Strategies to increase the expression of the wild-type SLC6A1 allele are likely to be beneficial across neurodevelopmental disorders, though the developmental stage and extent of required rescue remain unknown.
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Affiliation(s)
- Dina Buitrago Silva
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA, USA
| | - Marena Trinidad
- BioMarin Pharmaceutical Inc., Novato, CA, USA; Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA; Innovative Genomics Institute, University of California, Berkeley, Berkeley, CA, USA
| | - Alicia Ljungdahl
- Department of Psychiatry, UCSF Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA, USA; Institute of Developmental and Regenerative Medicine, Department of Paediatrics, University of Oxford, Oxford OX3 7TY, UK
| | - Jezrael L Revalde
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA, USA
| | | | | | - Cory S Patrick
- Department of Psychiatry, UCSF Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA, USA
| | | | - Michelle Arkin
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA, USA
| | - Shan Dong
- Department of Psychiatry, UCSF Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA, USA
| | | | - Keino Hutchinson
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | | | - Avner Schlessinger
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Katrine M Johannesen
- Department of Regional Health Research, Faculty of Health Sciences, University of Southern Denmark, Odense, Denmark
| | - Rikke S Møller
- Department of Regional Health Research, Faculty of Health Sciences, University of Southern Denmark, Odense, Denmark; Department of Epilepsy Genetics and Personalized Medicine, Member of ERN Epicare, Danish Epilepsy Centre, Dianalund, Denmark
| | - Kathleen M Giacomini
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA, USA
| | | | - Stephan J Sanders
- Department of Psychiatry, UCSF Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA, USA; Institute of Developmental and Regenerative Medicine, Department of Paediatrics, University of Oxford, Oxford OX3 7TY, UK.
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Dahshi H, Kalvakuntla S, Lee M, Goodspeed K. Beyond the Diagnosis: Evaluation of Quality-of-Life Measures and Family Functioning in SLC6A1-Related Neurodevelopmental Disorder. Pediatr Neurol 2024; 155:160-166. [PMID: 38663152 DOI: 10.1016/j.pediatrneurol.2024.03.030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Revised: 03/06/2024] [Accepted: 03/31/2024] [Indexed: 05/21/2024]
Abstract
BACKGROUND SLC6A1-related neurodevelopmental disorder (SLC6A1-NDD) is a rare genetic disorder linked to autism spectrum disorder, epilepsy, and developmental delay. In preparation for future clinical trials, understanding how the disorder impacts patients and their families is critically important. Quality-of-life (QoL) measures capture the overall disease experience of patients. This study presents QOL findings from our SLC6A1-NDD clinical trial readiness study and the Simons Searchlight SLC6A1-NDD registry. METHODS We compiled QoL data from participants with SLC6A1-NDD enrolled in our clinical trial readiness study (n = 20) and the Simons Searchlight registry (n = 32). We assessed the distribution of scores on the Quality-of-Life Inventory-Disability (QI Disability), Quality of Life of Childhood Epilepsy (QOLCE-55), and Pediatric Quality of Life Inventory Family Impact Module (PedsQL-FIM) administered to caregivers. RESULTS In our cohort of 52 participants, the mean QI Disability total score was 73 ± 12.3, the QOLCE-55 mean total score was 49 ± 17.1, and the mean total PedsQL score was 51 ± 17.6. Longitudinal QoL scores for a subset of participants (n = 7) demonstrated a reduction in the Family Relationship domain of PedsQL-FIM (Δ-10.0, P = 0.035). Bootstrap resampling of total scores displays nonoverlapping 95% confidence intervals for the 10th, 50th, and 90th percentiles on all three measures. CONCLUSIONS This is the first study to investigate QoL measures for SLC6A1-NDD. Findings suggest that scores within the 10th percentile's confidence interval could be clinically significant, referring to QI-Disability scores of <61, QOLCE-55 scores of <46, and PedsQL-FIM scores of <42. Future validation studies are needed.
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Affiliation(s)
- Hamza Dahshi
- University of Texas Southwestern Medical Center, O'Donnell Brain Institute, Dallas, Texas.
| | - Sanjana Kalvakuntla
- University of Texas Southwestern Medical Center, Medical School, Dallas, Texas
| | - MinJae Lee
- University of Texas Southwestern Medical Center, Peter O'Donnell Jr. School of Public Health, Dallas, Texas
| | - Kimberly Goodspeed
- Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, Texas; Department of Neurology, University of Texas Southwestern Medical Center, Dallas, Texas; Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, Texas.
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Leclert V, Laurencin C, Ameli R, Hermier M, Flaus A, Prange S, Lesca G, Thobois S. Globus Pallidus Lesion With Iron Deposition and Dopaminergic Denervation in a Patient With a Pathogenic SLC6A1 Variant: A Case Report. Neurol Genet 2024; 10:e200136. [PMID: 38515990 PMCID: PMC10955334 DOI: 10.1212/nxg.0000000000200136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Accepted: 01/19/2024] [Indexed: 03/23/2024]
Abstract
Objectives SLC6A1-related disorders encompass heterogeneous neuropsychiatric manifestations through GABAergic dysregulation, without any specific abnormalities on brain MRI, nor evidence of dopaminergic cell loss on I123-FP-β-CIT SPECT. We report here a case of globus pallidus lesions and dopaminergic denervation in a patient with a pathogenic SLC6A1 variant. Methods A 26-year-old female patient with intellectual disability, behavioral, and psychiatric disorders treated by neuroleptics for many years developed a parkinsonian syndrome associated with mild hand dystonia and chorea. A 3T brain MRI and I123-FP-β-CIT SPECT were performed. Results MRI of the brain found bilateral pallidal lesions consistent with neurodegeneration with iron accumulation. The I123-FP-β-CIT SPECT showed bilateral striatal presynaptic dopaminergic denervation. Whole-genome sequencing revealed a pathogenic SLC6A1 de novo variant. No additional variant was found in any of the genes responsible for Neurodegeneration with Brain Iron Accumulation (NBIA). Discussion This is a description of dopaminergic denervation and globus pallidus lesions with iron accumulation related to a SLC6A1 pathogenic variant. These findings expand the phenotype of SLC6A1-related disorder and suggest that it could be considered as a differential diagnosis of NBIA.
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Affiliation(s)
- Victoire Leclert
- From the Department of Neurology C (V.L., C.L., S.P., S.T.), Expert Parkinson Center NS-PARK/FCRIN, Hospices Civils de Lyon, Pierre Wertheimer Neurological Hospital, Bron; Lyon Neuroscience Research Center (C.L., A.F.), UMR5292, INSERM U1028/CNRS; Department of Neuroradiology (R.A., M.H.); Nuclear Medicine Department (A.F.), Hospices Civils de Lyon, Pierre Wertheimer Neurological Hospital; Marc Jeannerod Cognitive Neuroscience Institute (S.P., S.T.), CNRS, UMR 5229, Bron; Faculté de Médecine et Maïeutique Lyon Sud Charles-Mérieux (S.P., G.L., S.T.), Université de Lyon, Université Claude-Bernard Lyon I; Department of Genetics (G.L.), Hospices Civils de Lyon, Mother Child Hospital, Bron; and Physiopathology and Genetics of Neurons and Muscles (G.L.), UMR5261, U1315, Institut NeuroMyoGène, Lyon, France
| | - Chloe Laurencin
- From the Department of Neurology C (V.L., C.L., S.P., S.T.), Expert Parkinson Center NS-PARK/FCRIN, Hospices Civils de Lyon, Pierre Wertheimer Neurological Hospital, Bron; Lyon Neuroscience Research Center (C.L., A.F.), UMR5292, INSERM U1028/CNRS; Department of Neuroradiology (R.A., M.H.); Nuclear Medicine Department (A.F.), Hospices Civils de Lyon, Pierre Wertheimer Neurological Hospital; Marc Jeannerod Cognitive Neuroscience Institute (S.P., S.T.), CNRS, UMR 5229, Bron; Faculté de Médecine et Maïeutique Lyon Sud Charles-Mérieux (S.P., G.L., S.T.), Université de Lyon, Université Claude-Bernard Lyon I; Department of Genetics (G.L.), Hospices Civils de Lyon, Mother Child Hospital, Bron; and Physiopathology and Genetics of Neurons and Muscles (G.L.), UMR5261, U1315, Institut NeuroMyoGène, Lyon, France
| | - Roxana Ameli
- From the Department of Neurology C (V.L., C.L., S.P., S.T.), Expert Parkinson Center NS-PARK/FCRIN, Hospices Civils de Lyon, Pierre Wertheimer Neurological Hospital, Bron; Lyon Neuroscience Research Center (C.L., A.F.), UMR5292, INSERM U1028/CNRS; Department of Neuroradiology (R.A., M.H.); Nuclear Medicine Department (A.F.), Hospices Civils de Lyon, Pierre Wertheimer Neurological Hospital; Marc Jeannerod Cognitive Neuroscience Institute (S.P., S.T.), CNRS, UMR 5229, Bron; Faculté de Médecine et Maïeutique Lyon Sud Charles-Mérieux (S.P., G.L., S.T.), Université de Lyon, Université Claude-Bernard Lyon I; Department of Genetics (G.L.), Hospices Civils de Lyon, Mother Child Hospital, Bron; and Physiopathology and Genetics of Neurons and Muscles (G.L.), UMR5261, U1315, Institut NeuroMyoGène, Lyon, France
| | - Marc Hermier
- From the Department of Neurology C (V.L., C.L., S.P., S.T.), Expert Parkinson Center NS-PARK/FCRIN, Hospices Civils de Lyon, Pierre Wertheimer Neurological Hospital, Bron; Lyon Neuroscience Research Center (C.L., A.F.), UMR5292, INSERM U1028/CNRS; Department of Neuroradiology (R.A., M.H.); Nuclear Medicine Department (A.F.), Hospices Civils de Lyon, Pierre Wertheimer Neurological Hospital; Marc Jeannerod Cognitive Neuroscience Institute (S.P., S.T.), CNRS, UMR 5229, Bron; Faculté de Médecine et Maïeutique Lyon Sud Charles-Mérieux (S.P., G.L., S.T.), Université de Lyon, Université Claude-Bernard Lyon I; Department of Genetics (G.L.), Hospices Civils de Lyon, Mother Child Hospital, Bron; and Physiopathology and Genetics of Neurons and Muscles (G.L.), UMR5261, U1315, Institut NeuroMyoGène, Lyon, France
| | - Anthime Flaus
- From the Department of Neurology C (V.L., C.L., S.P., S.T.), Expert Parkinson Center NS-PARK/FCRIN, Hospices Civils de Lyon, Pierre Wertheimer Neurological Hospital, Bron; Lyon Neuroscience Research Center (C.L., A.F.), UMR5292, INSERM U1028/CNRS; Department of Neuroradiology (R.A., M.H.); Nuclear Medicine Department (A.F.), Hospices Civils de Lyon, Pierre Wertheimer Neurological Hospital; Marc Jeannerod Cognitive Neuroscience Institute (S.P., S.T.), CNRS, UMR 5229, Bron; Faculté de Médecine et Maïeutique Lyon Sud Charles-Mérieux (S.P., G.L., S.T.), Université de Lyon, Université Claude-Bernard Lyon I; Department of Genetics (G.L.), Hospices Civils de Lyon, Mother Child Hospital, Bron; and Physiopathology and Genetics of Neurons and Muscles (G.L.), UMR5261, U1315, Institut NeuroMyoGène, Lyon, France
| | - Stephane Prange
- From the Department of Neurology C (V.L., C.L., S.P., S.T.), Expert Parkinson Center NS-PARK/FCRIN, Hospices Civils de Lyon, Pierre Wertheimer Neurological Hospital, Bron; Lyon Neuroscience Research Center (C.L., A.F.), UMR5292, INSERM U1028/CNRS; Department of Neuroradiology (R.A., M.H.); Nuclear Medicine Department (A.F.), Hospices Civils de Lyon, Pierre Wertheimer Neurological Hospital; Marc Jeannerod Cognitive Neuroscience Institute (S.P., S.T.), CNRS, UMR 5229, Bron; Faculté de Médecine et Maïeutique Lyon Sud Charles-Mérieux (S.P., G.L., S.T.), Université de Lyon, Université Claude-Bernard Lyon I; Department of Genetics (G.L.), Hospices Civils de Lyon, Mother Child Hospital, Bron; and Physiopathology and Genetics of Neurons and Muscles (G.L.), UMR5261, U1315, Institut NeuroMyoGène, Lyon, France
| | - Gaetan Lesca
- From the Department of Neurology C (V.L., C.L., S.P., S.T.), Expert Parkinson Center NS-PARK/FCRIN, Hospices Civils de Lyon, Pierre Wertheimer Neurological Hospital, Bron; Lyon Neuroscience Research Center (C.L., A.F.), UMR5292, INSERM U1028/CNRS; Department of Neuroradiology (R.A., M.H.); Nuclear Medicine Department (A.F.), Hospices Civils de Lyon, Pierre Wertheimer Neurological Hospital; Marc Jeannerod Cognitive Neuroscience Institute (S.P., S.T.), CNRS, UMR 5229, Bron; Faculté de Médecine et Maïeutique Lyon Sud Charles-Mérieux (S.P., G.L., S.T.), Université de Lyon, Université Claude-Bernard Lyon I; Department of Genetics (G.L.), Hospices Civils de Lyon, Mother Child Hospital, Bron; and Physiopathology and Genetics of Neurons and Muscles (G.L.), UMR5261, U1315, Institut NeuroMyoGène, Lyon, France
| | - Stephane Thobois
- From the Department of Neurology C (V.L., C.L., S.P., S.T.), Expert Parkinson Center NS-PARK/FCRIN, Hospices Civils de Lyon, Pierre Wertheimer Neurological Hospital, Bron; Lyon Neuroscience Research Center (C.L., A.F.), UMR5292, INSERM U1028/CNRS; Department of Neuroradiology (R.A., M.H.); Nuclear Medicine Department (A.F.), Hospices Civils de Lyon, Pierre Wertheimer Neurological Hospital; Marc Jeannerod Cognitive Neuroscience Institute (S.P., S.T.), CNRS, UMR 5229, Bron; Faculté de Médecine et Maïeutique Lyon Sud Charles-Mérieux (S.P., G.L., S.T.), Université de Lyon, Université Claude-Bernard Lyon I; Department of Genetics (G.L.), Hospices Civils de Lyon, Mother Child Hospital, Bron; and Physiopathology and Genetics of Neurons and Muscles (G.L.), UMR5261, U1315, Institut NeuroMyoGène, Lyon, France
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Caraballo RH, Chacón S, Touzon MS, Loos M, Juanes M. De novo absence status epilepticus associated with the SLC6A1 gene in a pediatric patient. Epileptic Disord 2024; 26:233-235. [PMID: 37877664 DOI: 10.1002/epd2.20175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2023] [Revised: 10/10/2023] [Accepted: 10/22/2023] [Indexed: 10/26/2023]
Affiliation(s)
| | | | - Maria Sol Touzon
- Hospital de Pediatría "Prof. Dr. Juan P Garrahan", Buenos Aires, Argentina
| | - Mariana Loos
- Hospital de Pediatría "Prof. Dr. Juan P Garrahan", Buenos Aires, Argentina
| | - Matías Juanes
- Hospital de Pediatría "Prof. Dr. Juan P Garrahan", Buenos Aires, Argentina
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Chu WS, Ng J, Waddington SN, Kurian MA. Gene therapy for neurotransmitter-related disorders. J Inherit Metab Dis 2024; 47:176-191. [PMID: 38221762 PMCID: PMC11108624 DOI: 10.1002/jimd.12697] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Revised: 11/14/2023] [Accepted: 11/28/2023] [Indexed: 01/16/2024]
Abstract
Inborn errors of neurotransmitter (NT) metabolism are a group of rare, heterogenous diseases with predominant neurological features, such as movement disorders, autonomic dysfunction, and developmental delay. Clinical overlap with other disorders has led to delayed diagnosis and treatment, and some conditions are refractory to oral pharmacotherapies. Gene therapies have been developed and translated to clinics for paediatric inborn errors of metabolism, with 38 interventional clinical trials ongoing to date. Furthermore, efforts in restoring dopamine synthesis and neurotransmission through viral gene therapy have been developed for Parkinson's disease. Along with the recent European Medicines Agency (EMA) and Medicines and Healthcare Products Regulatory Agency (MHRA) approval of an AAV2 gene supplementation therapy for AADC deficiency, promising efficacy and safety profiles can be achieved in this group of diseases. In this review, we present preclinical and clinical advances to address NT-related diseases, and summarise potential challenges that require careful considerations for NT gene therapy studies.
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Affiliation(s)
- Wing Sum Chu
- Gene Transfer Technology Group, EGA Institute for Women's HealthUniversity College LondonLondonUK
- Genetic Therapy Accelerator Centre, Queen Square Institute of NeurologyUniversity College LondonLondonUK
| | - Joanne Ng
- Gene Transfer Technology Group, EGA Institute for Women's HealthUniversity College LondonLondonUK
- Genetic Therapy Accelerator Centre, Queen Square Institute of NeurologyUniversity College LondonLondonUK
| | - Simon N. Waddington
- Gene Transfer Technology Group, EGA Institute for Women's HealthUniversity College LondonLondonUK
- Wits/SAMRC Antiviral Gene Therapy Research Unit, Faculty of Health SciencesUniversity of the WitwatersrandJohannesburgSouth Africa
| | - Manju A. Kurian
- Developmental Neurosciences, Zayed Centre for Research into Rare Disease in Children, Great Ormond Street Institute of Child HealthUniversity College LondonLondonUK
- Department of NeurologyGreat Ormond Street Hospital for ChildrenLondonUK
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6
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Stefanski A, Pérez-Palma E, Brünger T, Montanucci L, Gati C, Klöckner C, Johannesen KM, Goodspeed K, Macnee M, Deng AT, Aledo-Serrano Á, Borovikov A, Kava M, Bouman AM, Hajianpour MJ, Pal DK, Engelen M, Hagebeuk EEO, Shinawi M, Heidlebaugh AR, Oetjens K, Hoffman TL, Striano P, Freed AS, Futtrup L, Balslev T, Abulí A, Danvoye L, Lederer D, Balci T, Nouri MN, Butler E, Drewes S, van Engelen K, Howell KB, Khoury J, May P, Trinidad M, Froelich S, Lemke JR, Tiller J, Freed AN, Kang JQ, Wuster A, Møller RS, Lal D. SLC6A1 variant pathogenicity, molecular function and phenotype: a genetic and clinical analysis. Brain 2023; 146:5198-5208. [PMID: 37647852 PMCID: PMC10689929 DOI: 10.1093/brain/awad292] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Revised: 06/05/2023] [Accepted: 07/08/2023] [Indexed: 09/01/2023] Open
Abstract
Genetic variants in the SLC6A1 gene can cause a broad phenotypic disease spectrum by altering the protein function. Thus, systematically curated clinically relevant genotype-phenotype associations are needed to understand the disease mechanism and improve therapeutic decision-making. We aggregated genetic and clinical data from 172 individuals with likely pathogenic/pathogenic (lp/p) SLC6A1 variants and functional data for 184 variants (14.1% lp/p). Clinical and functional data were available for a subset of 126 individuals. We explored the potential associations of variant positions on the GAT1 3D structure with variant pathogenicity, altered molecular function and phenotype severity using bioinformatic approaches. The GAT1 transmembrane domains 1, 6 and extracellular loop 4 (EL4) were enriched for patient over population variants. Across functionally tested missense variants (n = 156), the spatial proximity from the ligand was associated with loss-of-function in the GAT1 transporter activity. For variants with complete loss of in vitro GABA uptake, we found a 4.6-fold enrichment in patients having severe disease versus non-severe disease (P = 2.9 × 10-3, 95% confidence interval: 1.5-15.3). In summary, we delineated associations between the 3D structure and variant pathogenicity, variant function and phenotype in SLC6A1-related disorders. This knowledge supports biology-informed variant interpretation and research on GAT1 function. All our data can be interactively explored in the SLC6A1 portal (https://slc6a1-portal.broadinstitute.org/).
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Affiliation(s)
- Arthur Stefanski
- Genomic Medicine Institute and Epilepsy Center, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Eduardo Pérez-Palma
- Universidad del Desarrollo, Centro de Genética y Genómica, Facultad de Medicina Clínica Alemana, Santiago de Chile 7610658, Chile
| | - Tobias Brünger
- Cologne Center for Genomics (CCG), Medical Faculty of the University of Cologne, University Hospital of Cologne, Cologne 50931, Germany
| | - Ludovica Montanucci
- Genomic Medicine Institute and Epilepsy Center, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Cornelius Gati
- Department of Biological Sciences, Bridge Institute, USC Michelson Center for Convergent Bioscience, University of Southern California, Los Angeles, CA 90089, USA
| | - Chiara Klöckner
- Institute of Human Genetics, University of Leipzig Medical Center, Leipzig 04103, Germany
| | - Katrine M Johannesen
- Department of Epilepsy Genetics and Personalized Medicine, The Danish Epilepsy Centre, Dianalund 4293, Denmark
- Department of Genetics, University Hospital of Copenhagen, Rigshispitalet, Copenhagen 2100, Denmark
| | - Kimberly Goodspeed
- Children’s Health, Medical Center, Dallas, TX 75235, USA
- Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Marie Macnee
- Cologne Center for Genomics (CCG), Medical Faculty of the University of Cologne, University Hospital of Cologne, Cologne 50931, Germany
| | - Alexander T Deng
- Clinical Genetics, Guys and St Thomas NHS Trust, London SE19RT, UK
| | - Ángel Aledo-Serrano
- Epilepsy Program, Neurology Department, Hospital Ruber Internacional, Madrid 28034, Spain
| | - Artem Borovikov
- Research and Counseling Department, Research Centre for Medical Genetics, Moscow 115478, Russia
| | - Maina Kava
- Department of Neurology and Metabolic Medicine, Perth Children’s Hospital, Perth 6009, Australia
- School of Paediatrics and Child Health, UWA Medical School, University of Western Australia, Perth 6009, Australia
| | - Arjan M Bouman
- Department of Clinical Genetics, Erasmus MC, University Medical Center, Rotterdam 3015GD, The Netherlands
| | - M J Hajianpour
- Department of Pediatrics, Division of Medical Genetics and Genomics, Albany Medical College, Albany Med Health System, Albany, NY 12208, USA
| | - Deb K Pal
- Department of Basic and Clinical Neurosciences, Institute of Psychiatry, Psychology and Neuroscience, King’s College, London SE58AF, UK
- Department of Basic and Clinical Neurosciences, King’s College Hospital, London SE59RS, UK
| | - Marc Engelen
- Department of Pediatric Neurology, Amsterdam Public Health, Amsterdam University Medical Center, Amsterdam 1081HV, The Netherlands
| | - Eveline E O Hagebeuk
- Department of Pediatric Neurology, Stichting Epilepsie Instellingen Nederland (SEIN), Heemstede and Zwolle 2103SW, The Netherlands
| | - Marwan Shinawi
- Division of Genetics and Genomic Medicine, Department of Pediatrics, St.Louis Children’s Hospital, Washington University School of Medicine, St. Louis, MO 63110, USA
| | | | - Kathryn Oetjens
- Autism and Developmental Medicine Institute, Geisinger, Danville, PA 17837, USA
| | - Trevor L Hoffman
- Department of Regional Genetics, Anaheim, Southern California Kaiser Permanente Medical Group, CA 92806, USA
| | - Pasquale Striano
- Pediatric Neurology and Muscular Diseases Unit, IRCCS Istituto Giannina Gaslini, Genoa 16147, Italy
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, Genoa 16132, Italy
| | - Amanda S Freed
- Department of Clinical Science, Kaiser Permanente Bernard J. Tyson School of Medicine, Pasadena, CA 91101, USA
| | - Line Futtrup
- Department of Paediatrics, Regional Hospital of Central Jutland, Viborg 8800, Denmark
| | - Thomas Balslev
- Department of Paediatrics, Regional Hospital of Central Jutland, Viborg 8800, Denmark
- Centre for Educational Development, Aarhus University, Aarhus 8200, Denmark
| | - Anna Abulí
- Department of Clinical and Molecular Genetics and Medicine Genetics Group, VHIR, University Hospital Vall d’Hebron, Barcelona 08035, Spain
| | - Leslie Danvoye
- Department of Neurology, Université catholique de Louvain, Cliniques universitaires Saint-Luc, Brussels 1200, Belgium
| | - Damien Lederer
- Centre for Human Genetics, Institute for Pathology and Genetics, Gosselies 6041, Belgium
| | - Tugce Balci
- Department of Pediatrics, Division of Medical Genetics, Western University, London, ON N6A3K7, Canada
- Medical Genetics Program of Southwestern Ontario, London Health Sciences Centre and Children's Health Research Institute, London, ON N6A5A5, Canada
| | - Maryam Nabavi Nouri
- Department of Paediatrics, Division of Pediatric Neurology, London Health Sciences Centre, London, ON N6A5W9, Canada
| | | | - Sarah Drewes
- Department of Medical Genetics, UPMC Children’s Hospital of Pittsburgh, Pittsburgh, PA 15224, USA
| | - Kalene van Engelen
- Medical Genetics Program of Southwestern Ontario, London Health Sciences Centre, London, ON N6A5W9, Canada
| | - Katherine B Howell
- Department of Neurology, Royal Children’s Hospital, Melbourne, VIC 3052, Australia
- Department of Pediatrics, University of Melbourne, Melbourne, VIC 3052, Australia
- Murdoch Children’s Research Institute, Melbourne, VIC 3052, Australia
| | - Jean Khoury
- Genomic Medicine Institute and Epilepsy Center, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Patrick May
- Luxembourg Centre for Systems Biomedicine, University of Luxembourg, Esch-sur-Alzette 4362, Luxembourg
| | - Marena Trinidad
- Translational Genomics, BioMarin Pharmaceutical Inc., Novato, CA 94949, USA
| | - Steven Froelich
- Translational Genomics, BioMarin Pharmaceutical Inc., Novato, CA 94949, USA
| | - Johannes R Lemke
- Institute of Human Genetics, University of Leipzig Medical Center, Leipzig 04103, Germany
- Center for Rare Diseases, University of Leipzig Medical Center, Leipzig 04103, Germany
| | | | | | - Jing-Qiong Kang
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN 37240, USA
- Neuroscience Graduate Program, Vanderbilt University, Nashville, TN 37235, USA
- Department of Neurology, Vanderbilt Brain Institute, Nashville, TN 37235, USA
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA
- Vanderbilt Kennedy Center of Human Development, Nashville, TN 37203, USA
| | - Arthur Wuster
- Translational Genomics, BioMarin Pharmaceutical Inc., Novato, CA 94949, USA
| | - Rikke S Møller
- Department of Epilepsy Genetics and Personalized Medicine, The Danish Epilepsy Centre, Dianalund 4293, Denmark
- Department of Regional Health Research, University of Southern Denmark, Odense 5000, Denmark
| | - Dennis Lal
- Genomic Medicine Institute and Epilepsy Center, Cleveland Clinic, Cleveland, OH 44195, USA
- Stanley Center of Psychiatric Research, Broad Institute of Harvard and MIT, Cambridge, MA 02142, USA
- Department of Neurology, University of Texas Health Sciences Center at Houston, Houston, TX 77030, USA
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7
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Lindquist BE, Voskobiynyk Y, Goodspeed K, Paz JT. Patient-derived SLC6A1 variant S295L results in an epileptic phenotype similar to haploinsufficient mice. Epilepsia 2023; 64:e214-e221. [PMID: 37501613 PMCID: PMC10592270 DOI: 10.1111/epi.17731] [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: 03/31/2023] [Revised: 07/24/2023] [Accepted: 07/25/2023] [Indexed: 07/29/2023]
Abstract
The solute carrier family 6 member 1 (SLC6A1) gene encodes GAT-1, a γ-aminobutyric acid transporter expressed on astrocytes and inhibitory neurons. Mutations in SLC6A1 are associated with epilepsy and developmental disorders, including motor and social impairments, but variant-specific animal models are needed to elucidate mechanisms. Here, we report electrocorticographic (ECoG) recordings and clinical data from a patient with a variant in SLC6A1 that encodes GAT-1 with a serine-to-leucine substitution at amino acid 295 (S295L), who was diagnosed with childhood absence epilepsy. Next, we show that mice bearing the S295L mutation (GAT-1S295L/+ ) have spike-and-wave discharges with motor arrest consistent with absence-type seizures, similar to GAT-1+/- mice. GAT-1S295L/+ and GAT-1+/- mice follow the same pattern of pharmacosensitivity, being bidirectionally modulated by ethosuximide (200 mg/kg ip) and the GAT-1 antagonist NO-711 (10 mg/kg ip). By contrast, GAT-1-/- mice were insensitive to both ethosuximide and NO-711 at the doses tested. In conclusion, ECoG findings in GAT-1S295L/+ mice phenocopy GAT-1 haploinsufficiency and provide a useful preclinical model for drug screening and gene therapy investigations.
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Affiliation(s)
- Britta E. Lindquist
- Gladstone Institute of Neurological Disease, Gladstone Institutes, San Francisco, CA, 94158 USA
- University of California, San Francisco, Department of Neurology, Weill Institute, San Francisco, CA 94143 USA
| | - Yuliya Voskobiynyk
- Gladstone Institute of Neurological Disease, Gladstone Institutes, San Francisco, CA, 94158 USA
- University of California, San Francisco, Department of Neurology, Weill Institute, San Francisco, CA 94143 USA
| | | | - Jeanne T. Paz
- Gladstone Institute of Neurological Disease, Gladstone Institutes, San Francisco, CA, 94158 USA
- University of California, San Francisco, Department of Neurology, Weill Institute, San Francisco, CA 94143 USA
- Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, San Francisco, CA 94158 USA
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8
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Trivisano M, Butera A, Quintavalle C, De Dominicis A, Calabrese C, Cappelletti S, Vigevano F, Novelli A, Specchio N. Insights into cognitive and behavioral comorbidities of SLC6A1-related epilepsy: five new cases and literature review. Front Neurosci 2023; 17:1215684. [PMID: 37700749 PMCID: PMC10493279 DOI: 10.3389/fnins.2023.1215684] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Accepted: 08/04/2023] [Indexed: 09/14/2023] Open
Abstract
Introduction SLC6A1 pathogenic variants have been associated with epilepsy and neurodevelopmental disorders. The clinical phenotype includes different seizure types, intellectual disability, and psychiatric symptoms affecting mood and behavior. Few data regarding neuropsychological features have been described, and details on cognitive profiles are often missing due to the lack of standardized tests. Methods We retrospectively reviewed the neuropsychological assessments of five subjects carrying heterozygous missense genetic variants in SLC6A1. We also collected data on epileptic features, EEGs, and brain MRIs. Additionally, we reviewed neuropsychological data from 204 previously reported patients with SLC6A1 pathogenic variants. Results In our series, at the last evaluation (median 12.6 years), three patients had borderline intellectual functioning, one patient had mild cognitive impairment, and one patient presented with a moderate cognitive disability. Three out of five patients underwent at least two neuropsychological evaluations, which revealed a worsening of cognitive functions over time. We detected attention deficits in all patients. In addition, we observed anxiety, disruptive behavior disorder, emotional instability, and hetero aggressiveness. We also performed a literature review that highlighted that most of the patients with SLC6A1 pathogenic variants have mild-to-moderate intellectual disability and that one-third of cases have autistic traits. Discussion Based on the literature review and the detailed description of our cases, we conclude that patients with SLC6A1-related epilepsy mostly present with mild-to-moderate intellectual disability, often associated with attention disorders. Such symptoms may worsen over time. Periodic standardized neuropsychological tests may be useful tools to follow development over time, and patient-specific rehabilitation programs could be tailored consistently.
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Affiliation(s)
- Marina Trivisano
- Clinical and Experimental Neurology, Bambino Gesù Children’s Hospital, IRCCS, Full Member of European Reference Network EpiCARE, Rome, Italy
| | - Ambra Butera
- Clinical and Experimental Neurology, Bambino Gesù Children’s Hospital, IRCCS, Full Member of European Reference Network EpiCARE, Rome, Italy
- Unit of Child Neurology and Psychiatry, Department of Human Pathology of the Adult and Developmental age “Gaetano Barresi”, University of Messina, Messina, Italy
- PROMISE Department, School of Child Neurology and Psychiatry, University of Palermo, Palermo, Italy
| | - Chiara Quintavalle
- Clinical and Experimental Neurology, Bambino Gesù Children’s Hospital, IRCCS, Full Member of European Reference Network EpiCARE, Rome, Italy
| | - Angela De Dominicis
- Clinical and Experimental Neurology, Bambino Gesù Children’s Hospital, IRCCS, Full Member of European Reference Network EpiCARE, Rome, Italy
- Laboratory of Medical Genetics, Translational Cytogenomics Research Unit, Bambino Gesù Children’s Hospital, IRCCS, Rome, Italy
| | - Costanza Calabrese
- Clinical and Experimental Neurology, Bambino Gesù Children’s Hospital, IRCCS, Full Member of European Reference Network EpiCARE, Rome, Italy
| | - Simona Cappelletti
- Clinical and Experimental Neurology, Bambino Gesù Children’s Hospital, IRCCS, Full Member of European Reference Network EpiCARE, Rome, Italy
| | - Federico Vigevano
- Clinical and Experimental Neurology, Bambino Gesù Children’s Hospital, IRCCS, Full Member of European Reference Network EpiCARE, Rome, Italy
| | - Antonio Novelli
- Laboratory of Medical Genetics, Translational Cytogenomics Research Unit, Bambino Gesù Children’s Hospital, IRCCS, Rome, Italy
| | - Nicola Specchio
- Clinical and Experimental Neurology, Bambino Gesù Children’s Hospital, IRCCS, Full Member of European Reference Network EpiCARE, Rome, Italy
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9
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Johannesen KM, Nielsen J, Sabers A, Isidor B, Kattentidt-Mouravieva AA, Zieglgänsberger D, Heidlebaugh AR, Oetjens KF, Vidal AA, Christensen J, Tiller J, Freed AN, Møller RS, Rubboli G. The phenotypic presentation of adult individuals with SLC6A1-related neurodevelopmental disorders. Front Neurosci 2023; 17:1216653. [PMID: 37662110 PMCID: PMC10472133 DOI: 10.3389/fnins.2023.1216653] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Accepted: 08/03/2023] [Indexed: 09/05/2023] Open
Abstract
Introduction SLC6A1 is one of the most common monogenic causes of epilepsy and is a well-established cause of neurodevelopmental disorders. SLC6A1-neurodevelopmental disorders have a consistent phenotype of mild to severe intellectual disability (ID), epilepsy, language delay and behavioral disorders. This phenotypic description is mainly based on knowledge from the pediatric population. Method Here, we sought to describe patients with SLC6A1 variants and age above 18 years through the ascertainment of published and unpublished patients. Unpublished patients were ascertained through international collaborations, while previously published patients were collected through a literature search. Results A total of 15 adult patients with SLC6A1 variants were included. 9/13 patients had moderate to severe ID (data not available in two). Epilepsy was prevalent (11/15) with seizure types such as absence, myoclonic, atonic, and tonic-clonic seizures. Epilepsy was refractory in 7/11, while four patients were seizure free with lamotrigine, valproate, or lamotrigine in combination with valproate. Language development was severely impaired in five patients. Behavioral disorders were reported in and mainly consisted of autism spectrum disorders and aggressive behavior. Schizophrenia was not reported in any of the patients. Discussion The phenotype displayed in the adult patients presented here resembled that of the pediatric cohort with ID, epilepsy, and behavioral disturbances, indicating that the phenotype of SLC6A1-NDD is consistent over time. Seizures were refractory in >60% of the patients with epilepsy, indicating the lack of targeted treatment in SLC6A1-NDDs. With increased focus on repurposing drugs and on the development of new treatments, hope is that the outlook reflected here will change over time. ID appeared to be more severe in the adult patients, albeit this might reflect a recruitment bias, where only patients seen in specialized centers were included or it might be a feature of the natural history of SLC6A1-NDDs. This issue warrants to be explored in further studies in larger cohorts.
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Affiliation(s)
- Katrine M. Johannesen
- Department of Genetics, University Hospital of Copenhagen, Rigshospitalet, Copenhagen, Denmark
- Department of Epilepsy Genetics and Personalized Treatment, The Danish Epilepsy Centre, Member of the European Reference Network, EpiCARE, Dianalund, Denmark
| | - Jimmi Nielsen
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Mental Health Centre Glostrup, Copenhagen University Hospital, Capital Region of Denmark Mental Health Services, Glostrup, Denmark
| | - Anne Sabers
- Epilepsy Clinic, Department of Neurology, Rigshospitalet, University Hospital of Copenhagen, Copenhagen, Denmark
| | - Bertrand Isidor
- Service de Génétique Médicale, CHU de Nantes, Nantes, France
| | | | | | | | - Kathryn F. Oetjens
- Autism and Developmental Medicine Institute, Danville, VA, United States
| | - Anna Abuli Vidal
- Department of Clinical and Molecular Genetics, University Hospital Vall d’Hebron and Medicine Genetics Group Vall d'Hebron Research Institute (VHIR), Barcelona, Spain
| | - Jakob Christensen
- Department of Neurology, Aarhus University Hospital, Aarhus, Denmark
- National Centre for Register-based Research, Aarhus University, Aarhus, Denmark
- Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | | | | | - Rikke S. Møller
- Department of Epilepsy Genetics and Personalized Treatment, The Danish Epilepsy Centre, Member of the European Reference Network, EpiCARE, Dianalund, Denmark
- Department of Regional Health Research, Faculty of Health Sciences, University of Southern Denmark, Odense, Denmark
| | - Guido Rubboli
- Department of Epilepsy Genetics and Personalized Treatment, The Danish Epilepsy Centre, Member of the European Reference Network, EpiCARE, Dianalund, Denmark
- Institute of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark
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10
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Kassabian B, Fenger CD, Willems M, Aledo-Serrano A, Linnankivi T, McDonnell PP, Lusk L, Jepsen BS, Bayat M, Kattentidt-Mouravieva AA, Vidal AA, Valero-Lopez G, Alarcon-Martinez H, Goodspeed K, van Slegtenhorst M, Barakat TS, Møller RS, Johannesen KM, Rubboli G. Intrafamilial variability in SLC6A1-related neurodevelopmental disorders. Front Neurosci 2023; 17:1219262. [PMID: 37502687 PMCID: PMC10368872 DOI: 10.3389/fnins.2023.1219262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Accepted: 06/23/2023] [Indexed: 07/29/2023] Open
Abstract
Introduction Phenotypic spectrum of SLC6A1-related neurodevelopmental disorders (SLC6A1-NDD) includes intellectual disability (ID), autistic spectrum disorders (ASD), epilepsy, developmental delay, beginning from early infancy or after seizure onset, and other neurological features such as hypotonia and movement disorders. Data on familial phenotypic heterogeneity have been rarely reported, thus in our study we aimed to investigate intrafamilial phenotypic variability in families with SLC6A1 variants. Methods We collected clinical, laboratory and genetic data on 39 individuals, including 17 probands, belonging to 13 families harboring inherited variants of SLC6A1. Data were collected through an international network of Epilepsy and Genetic Centers. Results Main clinical findings in the whole cohort of 39 subjects were: (a) epilepsy, mainly presenting with generalized seizures, reported in 71% of probands and 36% of siblings or first/second-degree relatives. Within a family, the same epilepsy type (generalized or focal) was observed; (b) ID reported in 100% and in 13% of probands and siblings or first/second-degree relatives, respectively; (c) learning disabilities detected in 28% of the SLC6A1 carriers, all of them were relatives of a proband; (d) around 51% of the whole cohort presented with psychiatric symptoms or behavioral disorders, including 82% of the probands. Out of the 19 patients with psychiatric symptoms, ASD were diagnosed in 40% of them; (e) neurological findings (primarily tremor and speech difficulties) were observed 38.5% of the whole cohort, including 10 probands. Our families harbored 12 different SLC6A1 variants, one was a frameshift, two stop-gain, while the remaining were missense. No genotype-phenotype associations were identified. Discussion Our study showed that first-or second-degree relatives presented with a less severe phenotype, featuring mainly mild intellectual and/or learning disabilities, at variance with the probands who suffered from moderate to severe ID, generalized, sometimes intractable, epileptic seizures, behavioral and psychiatric disorders. These findings may suggest that a proportion of individuals with mild SLC6A1-NDD might be missed, in particular those with an older age where genetic testing is not performed. Further studies on intrafamilial phenotypic variability are needed to confirm our results and possibly to expand the phenotypic spectrum of these disorders and benefit genetic counseling.
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Affiliation(s)
- Benedetta Kassabian
- Department of Epilepsy Genetics and Precision Medicine, Danish Epilepsy Center, Member of the European Reference Network EpiCARE, Dianalund, Denmark
- Neurology Unit, Department of Neuroscience, University of Padua, Padua, Italy
| | - Christina Dühring Fenger
- Department of Epilepsy Genetics and Precision Medicine, Danish Epilepsy Center, Member of the European Reference Network EpiCARE, Dianalund, Denmark
- Amplexa Genetics, Odense, Denmark
| | - Marjolaine Willems
- Département Génétique Médicale, Maladies Rares et Médecine Personnalisée, Hôpital Arnaud de Villeneuve, CHU de Montpellier Institute for Neurosciences of Montpellier, Univ Montpellier, INSERM, Montpellier, France
| | - Angel Aledo-Serrano
- Epilepsy and Neurogenetics Program—Vithas Madrid La Milagrosa University Hospital, Vithas Hospital Group, Madrid, Spain
| | - Tarja Linnankivi
- Department of Pediatric Neurology, New Children's Hospital and Pediatric Research Center, Epilepsia Helsinki, Helsinki University Hospital and University of Helsinki, Helsinki, Finland
| | - Pamela Pojomovsky McDonnell
- Division of Neurology, Children's Hospital of Philadelphia, Philadelphia, PA, United States
- Department of Neurology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, United States
- Epilepsy Neurogenetics Initiative, Division of Neurology, Children's Hospital of Philadelphia, Philadelphia, PA, United States
| | - Laina Lusk
- Epilepsy Neurogenetics Initiative, Division of Neurology, Children's Hospital of Philadelphia, Philadelphia, PA, United States
| | | | - Michael Bayat
- Department of Neurology and Center for Rare Diseases, Aarhus University Hospital, Aarhus, Denmark
| | | | - Anna Abulí Vidal
- Department of Clinical and Molecular Genetics, University Hospital Vall d’Hebron and Medicine Genetics Group Vall d'Hebron Research Institute (VHIR), Barcelona, Spain
| | | | | | - Kimberly Goodspeed
- Department of Pediatrics, Division of Neurology, University of Texas Southwestern Medical Center, Dallas, TX, United States
- Department of Neurology, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Marjon van Slegtenhorst
- Department of Clinical Genetics, Erasmus MC University Medical Center, Rotterdam, Netherlands
| | - Tahsin Stefan Barakat
- Department of Clinical Genetics, Erasmus MC University Medical Center, Rotterdam, Netherlands
- Discovery Unit, Department of Clinical Genetics, Erasmus MC University Medical Center, Rotterdam, Netherlands
- ENCORE Expertise Center for Neurodevelopmental Disorders, Erasmus MC University Medical Center, Rotterdam, Netherlands
| | - Rikke S. Møller
- Department of Epilepsy Genetics and Precision Medicine, Danish Epilepsy Center, Member of the European Reference Network EpiCARE, Dianalund, Denmark
- Institute of Regional Health Research, University of Southern Denmark, Odense, Denmark
| | - Katrine M. Johannesen
- Department of Epilepsy Genetics and Precision Medicine, Danish Epilepsy Center, Member of the European Reference Network EpiCARE, Dianalund, Denmark
- Department of Genetics, University Hospital of Copenhagen, Rigshospitalet, Copenhagen, Denmark
| | - Guido Rubboli
- Department of Epilepsy Genetics and Precision Medicine, Danish Epilepsy Center, Member of the European Reference Network EpiCARE, Dianalund, Denmark
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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11
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Caputo D, Franceschetti S, Castellotti B, Freri E, Zorzi G, Saletti V, Canafoglia L, Granata T. Case report: SLC6A1 mutations presenting with isolated absence seizures: description of 2 novel cases. Front Neurosci 2023; 17:1219244. [PMID: 37457006 PMCID: PMC10339345 DOI: 10.3389/fnins.2023.1219244] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Accepted: 06/05/2023] [Indexed: 07/18/2023] Open
Abstract
We report the clinical and EEG data of two patients harboring heterozygous SLC6A1 mutations, who presented with typical absence seizures at 3 Hz spike and wave as well as with mild cognitive disability. Neuroradiological and other laboratory investigations were normal. Our observations suggest that SLC6A1 mutations can be suspected in children with typical absences as the only seizure type, especially if associated with, even mild, cognitive deficits.
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Affiliation(s)
- Davide Caputo
- Department of Pediatric Neuroscience, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Silvana Franceschetti
- Department of Neurophysiopathology, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Barbara Castellotti
- Department of Diagnostic and Technology, Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Elena Freri
- Department of Pediatric Neuroscience, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - G. Zorzi
- Department of Pediatric Neuroscience, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Veronica Saletti
- Department of Pediatric Neuroscience, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Laura Canafoglia
- Integrated Diagnostics for Epilepsy, Department of Diagnostic and Technology, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Tiziana Granata
- Department of Pediatric Neuroscience, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
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12
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Asadi-Pooya AA. Precision Medicine in Epilepsy Management; GET Application (Gene, Epilepsy, Treatment). Clin Neuropharmacol 2023; 46:95-97. [PMID: 37191562 DOI: 10.1097/wnf.0000000000000549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
Abstract
OBJECTIVES The aim was to develop a prototype of an application (app) that identifies the significance of discovered genes for further consideration in the treatment plan of patients with epilepsy (precision medicine). METHODS MEDLINE was systematically searched for related publications from inception to April 1, 2022. The following search strategy was implemented (title/abstract): "epilepsy" AND "precision" AND "medicine." The following data were extracted: genes, phenotypes associated with those genes, and the recommended treatments. Two other databases were searched to cross-check the retrieved data and add to the data: https://www.genecards.org and https://medlineplus.gov/genetics. Also, the original articles of the identified genes were retrieved. Genes with specific treatment strategies (ie, any specific drug to be selected or to be avoided and also any other specific therapies [eg, diets, supplements, etc]) were selected. RESULTS A database of 93 genes, which are associated with various epilepsy syndromes and for which specific treatment strategies have been suggested, was developed. CONCLUSIONS A Web-based app (a search engine) was developed accordingly that is freely available at http://get.yektaparnian.ir/, GET (Gene, Epilepsy, Treatment). When a patient comes to the clinic with a genetic diagnosis and a specific gene is identified, the physician enters the gene name into the search box, and the app shows whether this genetic epilepsy needs a specific treatment. This endeavor would benefit from input by experts in the field, and the Web site should be developed more comprehensively.
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Affiliation(s)
- Ali A Asadi-Pooya
- Shiraz University of Medical Sciences, Shiraz, Iran; and Thomas Jefferson University, Philadelphia, PA
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13
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Mori T, Sakamoto M, Tayama T, Goji A, Toda Y, Fujita A, Mizuguchi T, Urushihara M, Matsumoto N. A case of epilepsy with myoclonic atonic seizures caused by SLC6A1 gene mutation due to balanced chromosomal translocation. Brain Dev 2023:S0387-7604(23)00044-X. [PMID: 36966012 DOI: 10.1016/j.braindev.2023.03.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 03/02/2023] [Accepted: 03/05/2023] [Indexed: 03/27/2023]
Abstract
INTRODUCTION Epilepsy with myoclonic atonic seizures (EMAtS) was previously thought to occur in normally developing children. We report a female case of EMAtS and mild developmental delay before onset. Importantly, a de novo balanced chromosomal translocation was recognized in the patient. CASE PRESENTATION The patient was a 4-year-old girl. Mild developmental delay was observed during infancy. At the age of one and a half years, she developed atonic seizures once a month. At 4 years of age, her seizures increased to more than 10 times per hour. An ictal electroencephalogram (EEG) showed a 3-4-Hz spike-and-wave complex, which was consistent with atonic and myoclonic seizures of the trunk, eyelids, and lips. Therefore, EMAtS was diagnosed based on the symptoms and EEG findings. After administration of valproic acid (VPA), the epileptic seizures disappeared immediately. At the age of 5 years and 2 months, the seizures recurred but disappeared again when the dose of VPA was increased. Subsequently, no recurrence was observed until 6 years and 3 months of age on VPA and lamotrigine. Chromosome analysis of the patient disclosed 46,XX,t(3;11)(p25;q13.1)dn. Long-read sequencing of the the patient's genomic DNA revealed that the 3p25.3 translocation breakpoint disrupted the intron 7 of the SLC6A1 gene. CONCLUSION The SLC6A1 disruption by chromosome translocation well explains the clinical features of this patient. Long-read sequencing is a powerful technique to determine genomic abnormality at the nucleotide level for disease-associated chromosomal abnormality.
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Affiliation(s)
- Tatsuo Mori
- Department of Pediatrics, Graduate School of Biomedical Sciences, Tokushima University, Japan; Division of Epilepsy Center, Tokushima University Hospital, Japan.
| | - Masamune Sakamoto
- Department of Human Genetics, Yokohama City University, Graduate School of Medicine, Japan; Department of Pediatrics, Yokohama City University, Graduate School of Medicine, Yokohama, Japan
| | - Takahiro Tayama
- Department of Pediatrics, Graduate School of Biomedical Sciences, Tokushima University, Japan; Division of Epilepsy Center, Tokushima University Hospital, Japan
| | - Aya Goji
- Department of Pediatrics, Graduate School of Biomedical Sciences, Tokushima University, Japan; Division of Epilepsy Center, Tokushima University Hospital, Japan
| | - Yoshihiro Toda
- Department of Pediatrics, Graduate School of Biomedical Sciences, Tokushima University, Japan; Division of Epilepsy Center, Tokushima University Hospital, Japan
| | - Atsushi Fujita
- Department of Human Genetics, Yokohama City University, Graduate School of Medicine, Japan
| | - Takeshi Mizuguchi
- Department of Human Genetics, Yokohama City University, Graduate School of Medicine, Japan
| | - Maki Urushihara
- Department of Pediatrics, Graduate School of Biomedical Sciences, Tokushima University, Japan
| | - Naomichi Matsumoto
- Department of Pediatrics, Graduate School of Biomedical Sciences, Tokushima University, Japan
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14
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Astrocytes regulate inhibitory neurotransmission through GABA uptake, metabolism, and recycling. Essays Biochem 2023; 67:77-91. [PMID: 36806927 DOI: 10.1042/ebc20220208] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Revised: 01/03/2023] [Accepted: 01/05/2023] [Indexed: 02/23/2023]
Abstract
Synaptic regulation of the primary inhibitory neurotransmitter γ-aminobutyric acid (GABA) is essential for brain function. Cerebral GABA homeostasis is tightly regulated through multiple mechanisms and is directly coupled to the metabolic collaboration between neurons and astrocytes. In this essay, we outline and discuss the fundamental roles of astrocytes in regulating synaptic GABA signaling. A major fraction of synaptic GABA is removed from the synapse by astrocytic uptake. Astrocytes utilize GABA as a metabolic substrate to support glutamine synthesis. The astrocyte-derived glutamine is subsequently transferred to neurons where it serves as the primary precursor of neuronal GABA synthesis. The flow of GABA and glutamine between neurons and astrocytes is collectively termed the GABA-glutamine cycle and is essential to sustain GABA synthesis and inhibitory signaling. In certain brain areas, astrocytes are even capable of synthesizing and releasing GABA to modulate inhibitory transmission. The majority of oxidative GABA metabolism in the brain takes place in astrocytes, which also leads to synthesis of the GABA-related metabolite γ-hydroxybutyric acid (GHB). The physiological roles of endogenous GHB remain unclear, but may be related to regulation of tonic inhibition and synaptic plasticity. Disrupted inhibitory signaling and dysfunctional astrocyte GABA handling are implicated in several diseases including epilepsy and Alzheimer's disease. Synaptic GABA homeostasis is under astrocytic control and astrocyte GABA uptake, metabolism, and recycling may therefore serve as relevant targets to ameliorate pathological inhibitory signaling.
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15
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Chen S, Neale BM, Berkovic SF. Shared and distinct ultra-rare genetic risk for diverse epilepsies: A whole-exome sequencing study of 54,423 individuals across multiple genetic ancestries. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2023:2023.02.22.23286310. [PMID: 36865150 PMCID: PMC9980234 DOI: 10.1101/2023.02.22.23286310] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/03/2023]
Abstract
Identifying genetic risk factors for highly heterogeneous disorders like epilepsy remains challenging. Here, we present the largest whole-exome sequencing study of epilepsy to date to investigate rare variants that confer risk for a spectrum of epilepsy syndromes. With an unprecedented sample size of >54,000 human exomes, composed of 20,979 deep-phenotyped patients with epilepsy and 33,444 controls, we replicate previous gene findings at exome-wide significance; using a hypothesis-free approach, we identify potential novel associations. Most discoveries are specific to a particular subtype of epilepsy, highlighting distinct genetic contributions to different epilepsies. Combining evidence from rare single nucleotide/short indel-, copy number-, and common variants, we find convergence of different genetic risk factors at the level of individual genes. Further comparing to other exome-sequencing studies, we implicate shared rare variant risk between epilepsy and other neurodevelopmental disorders. Our study also demonstrates the value of collaborative sequencing and deep-phenotyping efforts, which will continue to unravel the complex genetic architecture underlying the heterogeneity of epilepsy.
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Affiliation(s)
- Siwei Chen
- Analytic and Translational Genetics Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA
- Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Benjamin M Neale
- Analytic and Translational Genetics Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA
- Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Samuel F Berkovic
- Epilepsy Research Centre, University of Melbourne, Austin Health, Heidelberg 3084, Australia
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Bryson A, Reid C, Petrou S. Fundamental Neurochemistry Review: GABA A receptor neurotransmission and epilepsy: Principles, disease mechanisms and pharmacotherapy. J Neurochem 2023; 165:6-28. [PMID: 36681890 DOI: 10.1111/jnc.15769] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 12/12/2022] [Accepted: 01/04/2023] [Indexed: 01/23/2023]
Abstract
Epilepsy is a common neurological disorder associated with alterations of excitation-inhibition balance within brain neuronal networks. GABAA receptor neurotransmission is the most prevalent form of inhibitory neurotransmission and is strongly implicated in both the pathophysiology and treatment of epilepsy, serving as a primary target for antiseizure medications for over a century. It is now established that GABA exerts a multifaceted influence through an array of GABAA receptor subtypes that extends far beyond simply negating excitatory activity. As the role of GABAA neurotransmission within inhibitory circuits is elaborated, this will enable the development of precision therapies that correct the network dysfunction underlying epileptic pathology.
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Affiliation(s)
- Alexander Bryson
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, Victoria, Australia.,Department of Neurology, Austin Health, Heidelberg, Victoria, Australia
| | - Christopher Reid
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, Victoria, Australia
| | - Steven Petrou
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, Victoria, Australia.,Praxis Precision Medicines, Inc., Cambridge, Massachusetts, USA
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17
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Kasture AS, Fischer FP, Kunert L, Burger ML, Burgstaller AC, El-Kasaby A, Hummel T, Sucic S. Drosophila melanogaster as a model for unraveling unique molecular features of epilepsy elicited by human GABA transporter 1 variants. Front Neurosci 2023; 16:1074427. [PMID: 36741049 PMCID: PMC9893286 DOI: 10.3389/fnins.2022.1074427] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Accepted: 12/21/2022] [Indexed: 01/20/2023] Open
Abstract
Mutations in the human γ-aminobutyric acid (GABA) transporter 1 (hGAT-1) can instigate myoclonic-atonic and other generalized epilepsies in the afflicted individuals. We systematically examined fifteen hGAT-1 disease variants, all of which dramatically reduced or completely abolished GABA uptake activity. Many of these loss-of-function variants were absent from their regular site of action at the cell surface, due to protein misfolding and/or impaired trafficking machinery (as verified by confocal microscopy and de-glycosylation experiments). A modest fraction of the mutants displayed correct targeting to the plasma membrane, but nonetheless rendered the mutated proteins devoid of GABA transport, possibly due to structural alterations in the GABA binding site/translocation pathway. We here focused on a folding-deficient A288V variant. In flies, A288V reiterated its impeded expression pattern, closely mimicking the ER-retention demonstrated in transfected HEK293 cells. Functionally, A288V presented a temperature-sensitive seizure phenotype in fruit flies. We employed diverse small molecules to restore the expression and activity of folding-deficient hGAT-1 epilepsy variants, in vitro (in HEK293 cells) and in vivo (in flies). We identified three compounds (chemical and pharmacological chaperones) conferring moderate rescue capacity for several variants. Our data grant crucial new insights into: (i) the molecular basis of epilepsy in patients harboring hGAT-1 mutations, and (ii) a proof-of-principle that protein folding deficits in disease-associated hGAT-1 variants can be corrected using the pharmacochaperoning approach. Such innovative pharmaco-therapeutic prospects inspire the rational design of novel drugs for alleviating the clinical symptoms triggered by the numerous emerging pathogenic mutations in hGAT-1.
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Affiliation(s)
- Ameya S. Kasture
- Institute of Pharmacology, Medical University of Vienna, Vienna, Austria,Department of Neuroscience and Developmental Biology, University of Vienna, Vienna, Austria
| | - Florian P. Fischer
- Institute of Pharmacology, Medical University of Vienna, Vienna, Austria,Department of Epileptology and Neurology, University of Aachen, Aachen, Germany
| | - Lisa Kunert
- Department of Neuroscience and Developmental Biology, University of Vienna, Vienna, Austria
| | - Melanie L. Burger
- Institute of Pharmacology, Medical University of Vienna, Vienna, Austria
| | | | - Ali El-Kasaby
- Institute of Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Thomas Hummel
- Department of Neuroscience and Developmental Biology, University of Vienna, Vienna, Austria
| | - Sonja Sucic
- Institute of Pharmacology, Medical University of Vienna, Vienna, Austria,*Correspondence: Sonja Sucic,
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18
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Goodspeed K, Mosca LR, Weitzel NC, Horning K, Simon EW, Pfalzer AC, Xia M, Langer K, Freed A, Bone M, Picone M, Bichell TJV. A draft conceptual model of SLC6A1 neurodevelopmental disorder. Front Neurosci 2023; 16:1026065. [PMID: 36741059 PMCID: PMC9893116 DOI: 10.3389/fnins.2022.1026065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Accepted: 12/05/2022] [Indexed: 01/21/2023] Open
Abstract
Introduction SLC6A1 Neurodevelopmental Disorder (SLC6A1-NDD), first described in 2015, is a rare syndrome caused by a mutation in the SLC6A1 gene which encodes for the GABA Transporter 1 (GAT-1) protein. Epilepsy is one of the most common symptoms in patients and is often the primary treatment target, though the severity of epilepsy is variable. The impact of seizures and other symptoms of SLC6A1-NDD on patients and caregivers is wide-ranging and has not been described in a formal disease concept study. Methods A literature search was performed using the simple search term, "SLC6A1." Papers published before 2015, and those which did not describe the human neurodevelopmental disorder were removed from analysis. Open-ended interviews on lived experiences were conducted with two patient advocate key opinion leaders. An analysis of de-identified conversations between families of people with SLC6A1-NDD on social media was performed to quantify topics of concern. Results Published literature described symptoms in all of the following domains: neurological, visual, motor, cognitive, communication, behavior, gastrointestinal, sleep, musculo-skeletal, and emotional in addition to epilepsy. Key opinion leaders noted two unpublished features: altered hand use in infants, and developmental regression with onset of epilepsy. Analysis of social media interactions confirmed that the core symptoms of epilepsy and autistic traits were prominent concerns, but also demonstrated that other symptoms have a large impact on family life. Discussion For rare diseases, analysis of published literature is important, but may not be as comprehensive as that which can be gleaned from spontaneous interactions between families and through qualitative interviews. This report reflects our current understanding of the lived experience of SLC6A1-NDD. The discrepancy between the domains of disease reported in the literature and those discussed in patient conversations suggests that a formal qualitative interview-based disease concept study of SLC6A1-NDD is warranted.
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Affiliation(s)
- Kimberly Goodspeed
- Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX, United States,*Correspondence: Kimberly Goodspeed,
| | - Lindsay R. Mosca
- College of Arts and Sciences, Vanderbilt University, Nashville, TN, United States
| | - Nicole C. Weitzel
- College of Arts and Sciences, Vanderbilt University, Nashville, TN, United States
| | | | - Elijah W. Simon
- College of Arts and Sciences, Vanderbilt University, Nashville, TN, United States
| | | | - Maya Xia
- COMBINEDBrain, Brentwood, TN, United States
| | - Katherine Langer
- College of Arts and Sciences, Vanderbilt University, Nashville, TN, United States
| | | | - Megan Bone
- Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Maria Picone
- TREND Community, Philadelphia, PA, United States
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19
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Lafferty MJ, Aygün N, Patel NK, Krupa O, Liang D, Wolter JM, Geschwind DH, de la Torre-Ubieta L, Stein JL. MicroRNA-eQTLs in the developing human neocortex link miR-4707-3p expression to brain size. eLife 2023; 12:e79488. [PMID: 36629315 PMCID: PMC9859047 DOI: 10.7554/elife.79488] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Accepted: 01/10/2023] [Indexed: 01/12/2023] Open
Abstract
Expression quantitative trait loci (eQTL) data have proven important for linking non-coding loci to protein-coding genes. But eQTL studies rarely measure microRNAs (miRNAs), small non-coding RNAs known to play a role in human brain development and neurogenesis. Here, we performed small-RNA sequencing across 212 mid-gestation human neocortical tissue samples, measured 907 expressed miRNAs, discovering 111 of which were novel, and identified 85 local-miRNA-eQTLs. Colocalization of miRNA-eQTLs with GWAS summary statistics yielded one robust colocalization of miR-4707-3p expression with educational attainment and brain size phenotypes, where the miRNA expression increasing allele was associated with decreased brain size. Exogenous expression of miR-4707-3p in primary human neural progenitor cells decreased expression of predicted targets and increased cell proliferation, indicating miR-4707-3p modulates progenitor gene regulation and cell fate decisions. Integrating miRNA-eQTLs with existing GWAS yielded evidence of a miRNA that may influence human brain size and function via modulation of neocortical brain development.
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Affiliation(s)
- Michael J Lafferty
- Department of Genetics, University of North Carolina at Chapel HillChapel HillUnited States
- UNC Neuroscience Center, University of North Carolina at Chapel HillChapel HillUnited States
| | - Nil Aygün
- Department of Genetics, University of North Carolina at Chapel HillChapel HillUnited States
- UNC Neuroscience Center, University of North Carolina at Chapel HillChapel HillUnited States
| | - Niyanta K Patel
- Department of Genetics, University of North Carolina at Chapel HillChapel HillUnited States
- UNC Neuroscience Center, University of North Carolina at Chapel HillChapel HillUnited States
| | - Oleh Krupa
- Department of Genetics, University of North Carolina at Chapel HillChapel HillUnited States
- UNC Neuroscience Center, University of North Carolina at Chapel HillChapel HillUnited States
| | - Dan Liang
- Department of Genetics, University of North Carolina at Chapel HillChapel HillUnited States
- UNC Neuroscience Center, University of North Carolina at Chapel HillChapel HillUnited States
| | - Justin M Wolter
- Department of Genetics, University of North Carolina at Chapel HillChapel HillUnited States
- UNC Neuroscience Center, University of North Carolina at Chapel HillChapel HillUnited States
- Department of Cell Biology and Physiology, The University of North Carolina at Chapel HillChapel HillUnited States
- Carolina Institute for Developmental Disabilities, The University of North Carolina at Chapel HillChapel HillUnited States
| | - Daniel H Geschwind
- Neurogenetics Program, Department of Neurology, David Geffen School of Medicine, University of California, Los AngelesLos AngelesUnited States
- Center for Autism Research and Treatment, Semel Institute, David Geffen School of Medicine, University of California, Los AngelesLos AngelesUnited States
- Department of Human Genetics, David Geffen School of Medicine, University of California, Los AngelesLos AngelesUnited States
- Department of Psychiatry and Biobehavioral Sciences, Semel Institute, David Geffen School of Medicine, University of California, Los AngelesLos AngelesUnited States
| | - Luis de la Torre-Ubieta
- Department of Psychiatry and Biobehavioral Sciences, Semel Institute, David Geffen School of Medicine, University of California, Los AngelesLos AngelesUnited States
| | - Jason L Stein
- Department of Genetics, University of North Carolina at Chapel HillChapel HillUnited States
- UNC Neuroscience Center, University of North Carolina at Chapel HillChapel HillUnited States
- Carolina Institute for Developmental Disabilities, The University of North Carolina at Chapel HillChapel HillUnited States
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20
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Experimental and Bioinformatic Insights into the Effects of Epileptogenic Variants on the Function and Trafficking of the GABA Transporter GAT-1. Int J Mol Sci 2023; 24:ijms24020955. [PMID: 36674476 PMCID: PMC9862756 DOI: 10.3390/ijms24020955] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 12/27/2022] [Accepted: 12/31/2022] [Indexed: 01/06/2023] Open
Abstract
In this article, we identified a novel epileptogenic variant (G307R) of the gene SLC6A1, which encodes the GABA transporter GAT-1. Our main goal was to investigate the pathogenic mechanisms of this variant, located near the neurotransmitter permeation pathway, and compare it with other variants located either in the permeation pathway or close to the lipid bilayer. The mutants G307R and A334P, close to the gates of the transporter, could be glycosylated with variable efficiency and reached the membrane, albeit inactive. Mutants located in the center of the permeation pathway (G297R) or close to the lipid bilayer (A128V, G550R) were retained in the endoplasmic reticulum. Applying an Elastic Network Model, to these and to other previously characterized variants, we found that G307R and A334P significantly perturb the structure and dynamics of the intracellular gate, which can explain their reduced activity, while for A228V and G362R, the reduced translocation to the membrane quantitatively accounts for the reduced activity. The addition of a chemical chaperone (4-phenylbutyric acid, PBA), which improves protein folding, increased the activity of GAT-1WT, as well as most of the assayed variants, including G307R, suggesting that PBA might also assist the conformational changes occurring during the alternative access transport cycle.
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21
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Kalvakuntla S, Lee M, Chung WK, Demarest S, Freed A, Horning KJ, Bichell TJ, Iannaccone ST, Goodspeed K. Patterns of developmental regression and associated clinical characteristics in SLC6A1-related disorder. Front Neurosci 2023; 17:1024388. [PMID: 36895422 PMCID: PMC9990465 DOI: 10.3389/fnins.2023.1024388] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2022] [Accepted: 02/02/2023] [Indexed: 02/23/2023] Open
Abstract
Introduction SLC6A1-related disorder is a genetic neurodevelopmental disorder that is caused by loss of function variants in the SLC6A1 gene. Solute Carrier Family 6 Member 1 (SLC6A1) gene encodes for gamma-aminobutyric acid (GABA) transporter type 1 (GAT1), which is responsible for reuptake of GABA from the synaptic cleft. Tight regulation of GABA levels plays an important role in brain development by balancing inhibitory and excitatory neuronal signaling. Consequently, individuals with SLC6A1-related disorder can have manifestations such as developmental delay, epilepsy, autism spectrum disorder, and a subset have developmental regression. Methods In this study, we identified patterns of developmental regression among a cohort of 24 patients with SLC6A1-related disorder and assessed for clinical characteristics associated with regression. We reviewed medical records of patients with SLC6A1-related disorder and divided subjects into two groups: 1) regression group and 2) control group. We described the patterns of developmental regression including whether there was a trigger prior to the regression, multiple episodes of regression, and whether or not skills were recovered. We assessed the relationship of clinical characteristics among the regression and control groups including demographic factors, seizures, developmental milestone acquisition, gastrointestinal problems, sleep problems, autism spectrum disorder, and behavioral problems. Results Individuals with developmental regression had a loss of skills that were previously mastered in developmental domains including speech and language, motor, social, and adaptive skills. The mean age at regression was 2.7 years and most subjects had regression of language or motor skills triggered by seizures, infection, or spontaneously. Although there was no significant difference in clinical characteristics between the two groups, there was a higher prevalence of autism and severe language impairment in the regression group. Discussion Future studies of a larger cohort of patients are required to make definitive conclusions. Developmental regression is often a sign of severe neurodevelopmental disability in genetic syndromes, but it is poorly understood in SLC6A1-related disorder. Understanding the patterns of developmental regression and the associated clinical characteristics in this rare disorder will be important to medical management, prognostication, and could impact the design of future clinical trials.
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Affiliation(s)
- Sanjana Kalvakuntla
- Medical School, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - MinJae Lee
- Peter O'Donnell Jr. School of Public Health, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Wendy K Chung
- Department of Pediatrics and Medicine, Columbia University, New York, NY, United States
| | - Scott Demarest
- Department of Pediatrics and Neurology, University of Colorado School of Medicine, Precision Medicine Institute, Children's Hospital Colorado, Aurora, CO, United States
| | | | | | | | - Susan T Iannaccone
- Department of Pediatrics, Division of Neurology, University of Texas Southwestern Medical Center, Dallas, TX, United States.,Department of Neurology, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Kimberly Goodspeed
- Department of Pediatrics, Division of Neurology, University of Texas Southwestern Medical Center, Dallas, TX, United States.,Department of Neurology, University of Texas Southwestern Medical Center, Dallas, TX, United States.,Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, TX, United States
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22
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Verhoeven W, Zuijdam J, Scheick A, van Nieuwenhuijsen F, Zwemer AS, Pfundt R, Egger J. Myoclonic-Atonic Epilepsy Caused by a Novel de Novo Heterozygous Missense Variant in the SLC6A1 Gene: Brief Discussion of the Literature and Detailed Case Description of a Severely Intellectually Disabled Adult Male Patient. Int Med Case Rep J 2022; 15:753-759. [PMID: 36582431 PMCID: PMC9793742 DOI: 10.2147/imcrj.s390636] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Accepted: 12/10/2022] [Indexed: 12/25/2022] Open
Abstract
Introduction Diagnostic exome sequencing has yielded over the past decades a great number of molecular diagnoses for genetic disorders in which both intellectual disability and epilepsy are present. One of these syndromes is myoclonic-atonic epilepsy (MAE) that is caused by pathogenic variants in the SLC6A1 gene located at 3p25.3. The most relevant clinical characteristics are intellectual disability, several forms of mostly treatment-resistant epilepsy starting at young age, serious disinhibitory behavioural problems, language impairment, higher pain tolerance, and symptoms from the autism spectrum, all in the absence of any consistent dysmorphism or malformation. Methods After an overview of the literature, here, the developmental trajectory of a 55-year-old severely intellectually disabled male with therapy-resistant epilepsy and aggressive outburst is reported in detail, in whom no etiological diagnosis had been performed. Next to genetic, neurological, and neuropsychiatric examination, psychological assessment with validated instruments was performed. Results Exome sequencing and targeted analysis of the patient and both his parents demonstrated a de novo missense variant in the SLC6A1 gene which was never before described in the literature nor in control databases. The phenotypical presentation of the patient with treatment-resistant epilepsy, especially absences and myoclonic seizures, as well as sleep disturbances and autism, corresponds with a diagnosis of MAE. Discussion This case stresses that exome sequencing should be the first-tier diagnostic test for patients with unexplained neurodevelopmental disorders, regardless of their age, and that as yet the most suitable approach is the formation of an interdisciplinary team for treatment design and clinical management.
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Affiliation(s)
- Willem Verhoeven
- Department of Psychiatry, Erasmus University Medical Center, Rotterdam, the Netherlands,Centre for Consultation and Expertise, Utrecht, the Netherlands,Vincent van Gogh Centre of Excellence for Neuropsychiatry, Venray, the Netherlands,Correspondence: Willem Verhoeven, Centre of Excellence for Neuropsychiatry, Stationsweg 46, Venray, 5803 AC, the Netherlands, Tel +31651156556, Fax +31478584765, Email
| | - José Zuijdam
- Raphael Institute Breidablick, Centre for People with Intellectual Disabilities, Middenbeemster, the Netherlands
| | - Anneke Scheick
- Raphael Institute Breidablick, Centre for People with Intellectual Disabilities, Middenbeemster, the Netherlands
| | | | - Anne-Suus Zwemer
- ASVZ, Centre for People with Intellectual Disabilities, Sliedrecht, the Netherlands
| | - Rolph Pfundt
- Department of Human Genetics, Radboud University Medical Centre, Nijmegen, the Netherlands,Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen, the Netherlands
| | - Jos Egger
- Vincent van Gogh Centre of Excellence for Neuropsychiatry, Venray, the Netherlands,Department of Human Genetics, Radboud University Medical Centre, Nijmegen, the Netherlands,Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen, the Netherlands
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23
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Mermer F, Poliquin S, Zhou S, Wang X, Ding Y, Yin F, Shen W, Wang J, Rigsby K, Xu D, Mack T, Nwosu G, Flamm C, Stein M, Kang JQ. Astrocytic GABA transporter 1 deficit in novel SLC6A1 variants mediated epilepsy: Connected from protein destabilization to seizures in mice and humans. Neurobiol Dis 2022; 172:105810. [PMID: 35840120 PMCID: PMC9472560 DOI: 10.1016/j.nbd.2022.105810] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 06/16/2022] [Accepted: 06/30/2022] [Indexed: 11/23/2022] Open
Abstract
OBJECTIVE Mutations in γ-aminobutyric acid (GABA) transporter 1 (GAT-1)-encoding SLC6A1 have been associated with myoclonic atonic epilepsy and other phenotypes. We determined the patho-mechanisms of the mutant GAT-1, in order to identify treatment targets. METHODS We conducted whole-exome sequencing of patients with myoclonic atonic epilepsy (MAE) and characterized the seizure phenotypes and EEG patterns. We studied the protein stability and structural changes with homology modeling and machine learning tools. We characterized the function and trafficking of the mutant GAT-1 with 3H radioactive GABA uptake assay and confocal microscopy. We utilized different models including a knockin mouse and human astrocytes derived from induced pluripotent stem cells (iPSCs). We focused on astrocytes because of their direct impact of astrocytic GAT-1 in seizures. RESULTS We identified four novel SLC6A1 variants associated with MAE and 2 to 4 Hz spike-wave discharges as a common EEG feature. Machine learning tools predicted that the variant proteins are destabilized. The variant protein had reduced expression and reduced GABA uptake due to endoplasmic reticular retention. The consistent observation was made in cortical and thalamic astrocytes from variant-knockin mice and human iPSC-derived astrocytes. The Slc6a+/A288V mouse, representative of MAE, had increased 5-7 Hz spike-wave discharges and absence seizures. INTERPRETATION SLC6A1 variants in various locations of the protein peptides can cause MAE with similar seizure phenotypes and EEG features. Reduced GABA uptake is due to decreased functional GAT-1, which, in thalamic astrocytes, could result in increased extracellular GABA accumulation and enhanced tonic inhibition, leading to seizures and abnormal EEGs.
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Affiliation(s)
- Felicia Mermer
- Department of Neurology, Vanderbilt University Medical Center, USA
| | - Sarah Poliquin
- The Neuroscience Program, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Shuizhen Zhou
- Department of Neurology, Children's Hospital, Fudan University, Shanghai, China
| | | | - Yifeng Ding
- Department of Neurology, Children's Hospital, Fudan University, Shanghai, China
| | - Fei Yin
- Department of Neurology, Xiangya Hospital of The Central-Southern University in Changsha, China
| | - Wangzhen Shen
- Department of Neurology, Vanderbilt University Medical Center, USA
| | - Juexin Wang
- Department of Electrical Engineering & Computer Science and Christopher S. Bond Life Sciences Center, University of Missouri, Columbia, MO 65211, USA
| | - Kathryn Rigsby
- The Neuroscience Program, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Dong Xu
- Department of Electrical Engineering & Computer Science and Christopher S. Bond Life Sciences Center, University of Missouri, Columbia, MO 65211, USA
| | - Taralynn Mack
- The Neuroscience Program, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Gerald Nwosu
- The Neuroscience Program, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Vanderbilt University-Meharry Medical College Alliance, Nashville, TN, 37232, USA
| | - Carson Flamm
- The Neuroscience Program, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Matthew Stein
- The Neuroscience Program, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Jing-Qiong Kang
- Department of Neurology, Vanderbilt University Medical Center, USA; Department of Pharmacology, Vanderbilt University, USA; Vanderbilt Kennedy Center of Human Development, University Medical Center, Nashville, TN, 37232, USA.
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24
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Chen C, Wen M, Jin Y. 1DE-MS Profiling for Proteoform-Correlated Proteomic Analysis, by Combining SDS-PAGE, Whole-Gel Slicing, Quantitative LC-MS/MS, and Reconstruction of Gel Distributions of Several Thousands of Proteins. J Proteome Res 2022; 21:2311-2330. [PMID: 36018058 DOI: 10.1021/acs.jproteome.2c00180] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
SDS-PAGE has often been used in proteomic analysis, but generally for sample prefractionation although the technique separates proteins by molecular masses (Mws) and the information would contribute to proteoform-level analysis. Here, we report a method that combines SDS-PAGE, whole-gel slicing, and quantitative LC-MS/MS for establishing gel distributions of several thousand proteins in a proteome. A previously obtained data set on rat cerebral cortex with cerebral ischemia-reperfusion injury1 was analyzed, and the gel distributions of 5906 proteins were reconstructed. These distributions, referred to as 1DE-MS profiles, revealed that about 30% of the proteins had more than one proteoform detected in the gels. The profiles were categorized into six types by distribution (narrow, dispersed, or broad) and relative deviations between the abundance-peak apparent Mws and calculated Mws. Only 56% of the proteins showed narrow distributions and matched Mws, while the others had rather complex profiles. Bioinformatic analysis on example profiles showed the resolved proteoforms involved alternative splicing, proteolytic processing, glycosylation and ubiquitination, fragmentation, and probably transmembrane structures. Profile-based differential analysis revealed that many of the disease-caused changes were proteoform dependent. This work provided a proteome-scale view of protein distributions in SDS-PAGE gels, and the method would be useful to obtain proteoform-correlated information for in-depth proteomics.
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Affiliation(s)
- Changming Chen
- Institute of Biomedical and Pharmaceutical Sciences, Guangdong University of Technology, Guangzhou 510006, P. R. China
| | - Meiling Wen
- Institute of Biomedical and Pharmaceutical Sciences, Guangdong University of Technology, Guangzhou 510006, P. R. China
| | - Ya Jin
- Institute of Biomedical and Pharmaceutical Sciences, Guangdong University of Technology, Guangzhou 510006, P. R. China
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25
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Abstract
Mounting evidence indicates that microglia, which are the resident immune cells of the brain, play critical roles in a diverse array of neurodevelopmental processes required for proper brain maturation and function. This evidence has ultimately led to growing speculation that microglial dysfunction may play a role in neurodevelopmental disorder (NDD) pathoetiology. In this review, we first provide an overview of how microglia mechanistically contribute to the sculpting of the developing brain and neuronal circuits. To provide an example of how disruption of microglial biology impacts NDD development, we also highlight emerging evidence that has linked microglial dysregulation to autism spectrum disorder pathogenesis. In recent years, there has been increasing interest in how the gut microbiome shapes microglial biology. In the last section of this review, we put a spotlight on this burgeoning area of microglial research and discuss how microbiota-dependent modulation of microglial biology is currently thought to influence NDD progression.
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Affiliation(s)
- John R Lukens
- Department of Neuroscience, University of Virginia School of Medicine, Charlottesville, Virginia, USA;
- Center for Brain Immunology and Glia, University of Virginia, Charlottesville, Virginia, USA
| | - Ukpong B Eyo
- Department of Neuroscience, University of Virginia School of Medicine, Charlottesville, Virginia, USA;
- Center for Brain Immunology and Glia, University of Virginia, Charlottesville, Virginia, USA
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26
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Bain JM, Snyder LG, Helbig KL, Cooper DD, Chung WK, Goodspeed K. Consistency of parent-report SLC6A1 data in Simons Searchlight with Provider-Based Publications. J Neurodev Disord 2022; 14:40. [PMID: 35761184 PMCID: PMC9238190 DOI: 10.1186/s11689-022-09449-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/02/2022] [Accepted: 06/17/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND SLC6A1-related disorder is a recently identified, rare, genetic neurodevelopmental disorder that is associated with loss-of-function variants in SLC6A1. This gene encodes GABA transporter type I that is responsible for re-uptake of GABA from the synapse into the pre-synaptic terminal or circulating neuroglia. Based upon retrospective review of published cases and available research databases including Epi25 collective and SLC6A1 Connect patient database, the phenotypic spectrum is broad and includes developmental delay, epilepsy, and autism or autistic traits. SLC6A1 is one of the genes included in the Simons Searchlight registry, which includes standardized data collection across genetically identified neurodevelopmental conditions. METHODS In this study, we compare parent-report measures of phenotypic features in the Simons Searchlight registry to previously published, provider-reported cases to assess if parent-report measures are consistent with what has been reported in the literature. RESULTS There were 116 participants in the provider-reported dataset compared to 43 individuals in the caregiver-reported dataset. Carriers in Searchlight had 83 unique pathogenic or likely pathogenic variants in SLC6A1, which were predominantly missense or nonsense variants. There was no significant difference between groups for the prevalence of developmental delay, ASD, or ADHD. Caregivers more often reported hypotonia, while epilepsy was slightly more frequently reported by providers. CONCLUSIONS We propose that standardized parent-report data collection methods are consistent with provider reports on many core features of SLC6A1-related disorder. The availability of patient registries and standardized natural history studies may fill an important need in clinical trial readiness programs, with larger sample sizes than smaller published case series.
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Affiliation(s)
- Jennifer M Bain
- Department of Neurology, Division of Child Neurology, Columbia University Irving Medical Center, New York, NY, USA.
| | | | - Katherine L Helbig
- Department of Pediatrics, Division of Neurology and Epilepsy NeuroGenetics Initiative, Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | | | - Wendy K Chung
- Simons Foundation, New York, NY, USA.,Department of Pediatrics, Columbia University Irving Medical Center, New York, NY, USA
| | - Kimberly Goodspeed
- Department of Pediatrics, Division of Neurology, University of Texas Southwestern Medical Center, Dallas, TX, USA
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27
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Goodspeed K, Bailey RM, Prasad S, Sadhu C, Cardenas JA, Holmay M, Bilder DA, Minassian BA. Gene Therapy: Novel Approaches to Targeting Monogenic Epilepsies. Front Neurol 2022; 13:805007. [PMID: 35847198 PMCID: PMC9284605 DOI: 10.3389/fneur.2022.805007] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Accepted: 04/20/2022] [Indexed: 11/18/2022] Open
Abstract
Genetic epilepsies are a spectrum of disorders characterized by spontaneous and recurrent seizures that can arise from an array of inherited or de novo genetic variants and disrupt normal brain development or neuronal connectivity and function. Genetically determined epilepsies, many of which are due to monogenic pathogenic variants, can result in early mortality and may present in isolation or be accompanied by neurodevelopmental disability. Despite the availability of more than 20 antiseizure medications, many patients with epilepsy fail to achieve seizure control with current therapies. Patients with refractory epilepsy—particularly of childhood onset—experience increased risk for severe disability and premature death. Further, available medications inadequately address the comorbid developmental disability. The advent of next-generation gene sequencing has uncovered genetic etiologies and revolutionized diagnostic practices for many epilepsies. Advances in the field of gene therapy also present the opportunity to address the underlying mechanism of monogenic epilepsies, many of which have only recently been described due to advances in precision medicine and biology. To bring precision medicine and genetic therapies closer to clinical applications, experimental animal models are needed that replicate human disease and reflect the complexities of these disorders. Additionally, identifying and characterizing clinical phenotypes, natural disease course, and meaningful outcome measures from epileptic and neurodevelopmental perspectives are necessary to evaluate therapies in clinical studies. Here, we discuss the range of genetically determined epilepsies, the existing challenges to effective clinical management, and the potential role gene therapy may play in transforming treatment options available for these conditions.
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Affiliation(s)
- Kimberly Goodspeed
- Division of Child Neurology, Department of Pediatrics, University of Texas Southwestern, Dallas, TX, United States
| | - Rachel M. Bailey
- Division of Child Neurology, Department of Pediatrics, University of Texas Southwestern, Dallas, TX, United States
- Center for Alzheimer's and Neurodegenerative Diseases, University of Texas Southwestern, Dallas, TX, United States
| | - Suyash Prasad
- Department of Research and Development, Taysha Gene Therapies, Dallas, TX, United States
| | - Chanchal Sadhu
- Department of Research and Development, Taysha Gene Therapies, Dallas, TX, United States
| | - Jessica A. Cardenas
- Department of Research and Development, Taysha Gene Therapies, Dallas, TX, United States
| | - Mary Holmay
- Department of Research and Development, Taysha Gene Therapies, Dallas, TX, United States
| | - Deborah A. Bilder
- Division of Child and Adolescent Psychiatry, Department of Psychiatry, Huntsman Mental Health Institute, University of Utah, Salt Lake City, UT, United States
| | - Berge A. Minassian
- Division of Child Neurology, Department of Pediatrics, University of Texas Southwestern, Dallas, TX, United States
- *Correspondence: Berge A. Minassian
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28
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Nwosu G, Mermer F, Flamm C, Poliquin S, Shen W, Rigsby K, Kang JQ. 4-Phenylbutyrate restored γ-aminobutyric acid uptake and reduced seizures in SLC6A1 patient variant-bearing cell and mouse models. Brain Commun 2022; 4:fcac144. [PMID: 35911425 PMCID: PMC9336585 DOI: 10.1093/braincomms/fcac144] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Revised: 03/17/2022] [Accepted: 05/30/2022] [Indexed: 11/29/2022] Open
Abstract
We have studied the molecular mechanisms of variants in solute carrier Family 6 Member 1 associated with neurodevelopmental disorders, including various epilepsy syndromes, autism and intellectual disability. Based on functional assays of solute carrier Family 6 Member 1 variants, we conclude that partial or complete loss of γ-amino butyric acid uptake due to reduced membrane γ-amino butyric acid transporter 1 trafficking is the primary aetiology. Importantly, we identified common patterns of the mutant γ-amino butyric acid transporter 1 protein trafficking from biogenesis, oligomerization, glycosylation and translocation to the cell membrane across variants in different cell types such as astrocytes and neurons. We hypothesize that therapeutic approaches to facilitate membrane trafficking would increase γ-amino butyric acid transporter 1 protein membrane expression and function. 4-Phenylbutyrate is a Food and Drug Administration-approved drug for paediatric use and is orally bioavailable. 4-Phenylbutyrate shows promise in the treatment of cystic fibrosis. The common cellular mechanisms shared by the mutant γ-amino butyric acid transporter 1 and cystic fibrosis transmembrane conductance regulator led us to hypothesize that 4-phenylbutyrate could be a potential treatment option for solute carrier Family 6 Member 1 mutations. We examined the impact of 4-phenylbutyrate across a library of variants in cell and knockin mouse models. Because γ-amino butyric acid transporter 1 is expressed in both neurons and astrocytes, and γ-amino butyric acid transporter 1 deficiency in astrocytes has been hypothesized to underlie seizure generation, we tested the effect of 4-phenylbutyrate in both neurons and astrocytes with a focus on astrocytes. We demonstrated existence of the mutant γ-amino butyric acid transporter 1 retaining wildtype γ-amino butyric acid transporter 1, suggesting the mutant protein causes aberrant protein oligomerization and trafficking. 4-Phenylbutyrate increased γ-amino butyric acid uptake in both mouse and human astrocytes and neurons bearing the variants. Importantly, 4-phenylbutyrate alone increased γ-amino butyric acid transporter 1 expression and suppressed spike wave discharges in heterozygous knockin mice. Although the mechanisms of action for 4-phenylbutyrate are still unclear, with multiple possibly being involved, it is likely that 4-phenylbutyrate can facilitate the forward trafficking of the wildtype γ-amino butyric acid transporter 1 regardless of rescuing the mutant γ-amino butyric acid transporter 1, thus increasing γ-amino butyric acid uptake. All patients with solute carrier Family 6 Member 1 variants are heterozygous and carry one wildtype allele, suggesting a great opportunity for treatment development leveraging wildtype protein trafficking. The study opens a novel avenue of treatment development for genetic epilepsy via drug repurposing.
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Affiliation(s)
| | | | - Carson Flamm
- Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN, USA
| | - Sarah Poliquin
- Department of Neurology, Vanderbilt University Medical Center, 465 21st Ave South, Nashville, TN 37232, USA,Neuroscience Graduate Program, Vanderbilt University, Nashville, TN, USA,Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN, USA
| | - Wangzhen Shen
- Department of Neurology, Vanderbilt University Medical Center, 465 21st Ave South, Nashville, TN 37232, USA
| | - Kathryn Rigsby
- Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN, USA
| | - Jing Qiong Kang
- Correspondence to: Jing-Qiong Kang Department of Neurology and Pharmacology Vanderbilt University Medical Center 465 21st Ave south, Nashville, TN 37232, USA E-mails: ;
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29
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Absalom NL, Liao VWY, Johannesen KMH, Gardella E, Jacobs J, Lesca G, Gokce-Samar Z, Arzimanoglou A, Zeidler S, Striano P, Meyer P, Benkel-Herrenbrueck I, Mero IL, Rummel J, Chebib M, Møller RS, Ahring PK. Gain-of-function and loss-of-function GABRB3 variants lead to distinct clinical phenotypes in patients with developmental and epileptic encephalopathies. Nat Commun 2022; 13:1822. [PMID: 35383156 PMCID: PMC8983652 DOI: 10.1038/s41467-022-29280-x] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Accepted: 03/08/2022] [Indexed: 12/23/2022] Open
Abstract
Many patients with developmental and epileptic encephalopathies present with variants in genes coding for GABAA receptors. These variants are presumed to cause loss-of-function receptors leading to reduced neuronal GABAergic activity. Yet, patients with GABAA receptor variants have diverse clinical phenotypes and many are refractory to treatment despite the availability of drugs that enhance GABAergic activity. Here we show that 44 pathogenic GABRB3 missense variants segregate into gain-of-function and loss-of-function groups and respective patients display distinct clinical phenotypes. The gain-of-function cohort (n = 27 patients) presented with a younger age of seizure onset, higher risk of severe intellectual disability, focal seizures at onset, hypotonia, and lower likelihood of seizure freedom in response to treatment. Febrile seizures at onset are exclusive to the loss-of-function cohort (n = 47 patients). Overall, patients with GABRB3 variants that increase GABAergic activity have more severe developmental and epileptic encephalopathies. This paradoxical finding challenges our current understanding of the GABAergic system in epilepsy and how patients should be treated.
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Affiliation(s)
- Nathan L Absalom
- Brain and Mind Centre, School of Pharmacy, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia.,School of Science, Western Sydney University, Sydney, NSW, Australia
| | - Vivian W Y Liao
- Brain and Mind Centre, School of Pharmacy, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
| | - Katrine M H Johannesen
- Department of Epilepsy Genetics and Personalized Treatment, Member of the ERN EpiCARE, The Danish Epilepsy Centre, Dianalund, Denmark.,Department of Regional Health Research, University of Southern Denmark, Odense, Denmark
| | - Elena Gardella
- Department of Epilepsy Genetics and Personalized Treatment, Member of the ERN EpiCARE, The Danish Epilepsy Centre, Dianalund, Denmark.,Department of Regional Health Research, University of Southern Denmark, Odense, Denmark
| | - Julia Jacobs
- Department of Neuropediatrics and Muscle Disorders, Medical Center-University of Freiburg, Freiburg, Germany.,Department of Paediatrics and Department of Neuroscience, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada.,Hotchkiss Brain Institute and Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB, Canada
| | - Gaetan Lesca
- Department of Medical Genetics, Member of the ERN EpiCARE, University Hospitals of Lyon (HCL), Lyon, France.,Institut Neuromyogène, CNRS UMR 5310 - INSERM U1217, Université de Lyon, Université Claude Bernard Lyon 1, Lyon, France
| | - Zeynep Gokce-Samar
- Department of Paediatric Clinical Epileptology, Sleep Disorders and Functional Neurology, Member of the ERN EpiCARE, University Hospitals of Lyon (HCL), Lyon, France
| | - Alexis Arzimanoglou
- Department of Paediatric Clinical Epileptology, Sleep Disorders and Functional Neurology, Member of the ERN EpiCARE, University Hospitals of Lyon (HCL), Lyon, France
| | - Shimriet Zeidler
- Department of Clinical Genetics, Erasmus MC, Rotterdam, The Netherlands
| | - Pasquale Striano
- IRCCS Institute "Giannina Gaslini", Genova, Italy.,Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genova, Genova, Italy
| | - Pierre Meyer
- Pediatric Neurology Department, Phymedexp, Montpellier University, Inserm, CRNS, Montpellier University Hospital, Montpellier, France
| | - Ira Benkel-Herrenbrueck
- Sana-Krankenhaus Düsseldorf-Gerresheim, Academic Teaching Hospital der Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
| | - Inger-Lise Mero
- Department of Medical Genetics, Oslo University Hospital, Oslo, Norway
| | - Jutta Rummel
- Department of Neurohabilitation, Oslo University Hospital, Oslo, Norway
| | - Mary Chebib
- Brain and Mind Centre, School of Pharmacy, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
| | - Rikke S Møller
- Department of Epilepsy Genetics and Personalized Treatment, Member of the ERN EpiCARE, The Danish Epilepsy Centre, Dianalund, Denmark. .,Department of Regional Health Research, University of Southern Denmark, Odense, Denmark.
| | - Philip K Ahring
- Brain and Mind Centre, School of Pharmacy, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia.
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30
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Fischer FP, Kasture AS, Hummel T, Sucic S. Molecular and Clinical Repercussions of GABA Transporter 1 Variants Gone Amiss: Links to Epilepsy and Developmental Spectrum Disorders. Front Mol Biosci 2022; 9:834498. [PMID: 35295842 PMCID: PMC7612498 DOI: 10.3389/fmolb.2022.834498] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Accepted: 02/01/2022] [Indexed: 12/15/2022] Open
Abstract
The human γ-aminobutyric acid (GABA) transporter 1 (hGAT-1) is the first member of the solute carrier 6 (SLC6) protein superfamily. GAT-1 (SLC6A1) is one of the main GABA transporters in the central nervous system. Its principal physiological role is retrieving GABA from the synapse into neurons and astrocytes, thus swiftly terminating neurotransmission. GABA is a key inhibitory neurotransmitter and shifts in GABAergic signaling can lead to pathological conditions, from anxiety and epileptic seizures to schizophrenia. Point mutations in the SLC6A1 gene frequently give rise to epilepsy, intellectual disability or autism spectrum disorders in the afflicted individuals. The mechanistic routes underlying these are still fairly unclear. Some loss-of-function variants impair the folding and intracellular trafficking of the protein (thus retaining the transporter in the endoplasmic reticulum compartment), whereas others, despite managing to reach their bona fide site of action at the cell surface, nonetheless abolish GABA transport activity (plausibly owing to structural/conformational defects). Whatever the molecular culprit(s), the physiological aftermath transpires into the absence of functional transporters, which in turn perturbs GABAergic actions. Dozens of mutations in the kin SLC6 family members are known to exhort protein misfolding. Such events typically elicit severe ailments in people, e.g., infantile parkinsonism-dystonia or X-linked intellectual disability, in the case of dopamine and creatine transporters, respectively. Flaws in protein folding can be rectified by small molecules known as pharmacological and/or chemical chaperones. The search for such apt remedies calls for a systematic investigation and categorization of the numerous disease-linked variants, by biochemical and pharmacological means in vitro (in cell lines and primary neuronal cultures) and in vivo (in animal models). We here give special emphasis to the utilization of the fruit fly Drosophila melanogaster as a versatile model in GAT-1-related studies. Jointly, these approaches can portray indispensable insights into the molecular factors underlying epilepsy, and ultimately pave the way for contriving efficacious therapeutic options for patients harboring pathogenic mutations in hGAT-1.
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Affiliation(s)
- Florian P. Fischer
- Institute of Pharmacology, Medical University of Vienna, Vienna, Austria
- Department of Epileptology and Neurology, University of Aachen, Aachen, Germany
| | - Ameya S. Kasture
- Department of Neuroscience and Developmental Biology, University of Vienna, Vienna, Austria
| | - Thomas Hummel
- Department of Neuroscience and Developmental Biology, University of Vienna, Vienna, Austria
| | - Sonja Sucic
- Institute of Pharmacology, Medical University of Vienna, Vienna, Austria
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31
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Wilson CS, Dohare P, Orbeta S, Nalwalk JW, Huang Y, Ferland RJ, Sah R, Scimemi A, Mongin AA. Late adolescence mortality in mice with brain-specific deletion of the volume-regulated anion channel subunit LRRC8A. FASEB J 2021; 35:e21869. [PMID: 34469026 PMCID: PMC8639177 DOI: 10.1096/fj.202002745r] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 07/27/2021] [Accepted: 08/09/2021] [Indexed: 11/11/2022]
Abstract
The leucine-rich repeat-containing family 8 member A (LRRC8A) is an essential subunit of the volume-regulated anion channel (VRAC). VRAC is critical for cell volume control, but its broader physiological functions remain under investigation. Recent studies in the field indicate that Lrrc8a disruption in the brain astrocytes reduces neuronal excitability, impairs synaptic plasticity and memory, and protects against cerebral ischemia. In the present work, we generated brain-wide conditional LRRC8A knockout mice (LRRC8A bKO) using NestinCre -driven Lrrc8aflox/flox excision in neurons, astrocytes, and oligodendroglia. LRRC8A bKO animals were born close to the expected Mendelian ratio and developed without overt histological abnormalities, but, surprisingly, all died between 5 and 9 weeks of age with a seizure phenotype, which was confirmed by video and EEG recordings. Brain slice electrophysiology detected changes in the excitability of pyramidal cells and modified GABAergic inputs in the hippocampal CA1 region of LRRC8A bKO. LRRC8A-null hippocampi showed increased immunoreactivity of the astrocytic marker GFAP, indicating reactive astrogliosis. We also found decreased whole-brain protein levels of the GABA transporter GAT-1, the glutamate transporter GLT-1, and the astrocytic enzyme glutamine synthetase. Complementary HPLC assays identified reduction in the tissue levels of the glutamate and GABA precursor glutamine. Together, these findings suggest that VRAC provides vital control of brain excitability in mouse adolescence. VRAC deletion leads to a lethal phenotype involving progressive astrogliosis and dysregulation of astrocytic uptake and supply of amino acid neurotransmitters and their precursors.
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Affiliation(s)
- Corinne S Wilson
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, New York, USA
| | - Preeti Dohare
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, New York, USA
| | - Shaina Orbeta
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, New York, USA
| | - Julia W Nalwalk
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, New York, USA
| | - Yunfei Huang
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, New York, USA
| | - Russell J Ferland
- Department of Biomedical Sciences, University of New England College of Osteopathic Medicine, Biddeford, Maine, USA
| | - Rajan Sah
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Annalisa Scimemi
- Department of Biology, University at Albany, State University of New York, Albany, New York, USA
| | - Alexander A Mongin
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, New York, USA
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32
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Cheng JZ, Carvill GL. Pathogenic mechanisms underlying SLC6A1 variant-mediated neurodevelopmental disorders. Brain 2021; 144:2237-2239. [PMID: 34283886 DOI: 10.1093/brain/awab259] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Accepted: 07/02/2021] [Indexed: 11/13/2022] Open
Abstract
This scientific commentary refers to ‘Common molecular mechanisms of SLC6A1 variant-mediated neurodevelopmental disorders in astrocytes and neurons’ by Mermer et al. (doi:10.1093/brain/awab207).
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Affiliation(s)
- Jennifer Z Cheng
- Ken and Ruth Davee Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL, 60610, USA
| | - Gemma L Carvill
- Ken and Ruth Davee Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL, 60610, USA
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33
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Gobbo D, Scheller A, Kirchhoff F. From Physiology to Pathology of Cortico-Thalamo-Cortical Oscillations: Astroglia as a Target for Further Research. Front Neurol 2021; 12:661408. [PMID: 34177766 PMCID: PMC8219957 DOI: 10.3389/fneur.2021.661408] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Accepted: 05/11/2021] [Indexed: 12/21/2022] Open
Abstract
The electrographic hallmark of childhood absence epilepsy (CAE) and other idiopathic forms of epilepsy are 2.5-4 Hz spike and wave discharges (SWDs) originating from abnormal electrical oscillations of the cortico-thalamo-cortical network. SWDs are generally associated with sudden and brief non-convulsive epileptic events mostly generating impairment of consciousness and correlating with attention and learning as well as cognitive deficits. To date, SWDs are known to arise from locally restricted imbalances of excitation and inhibition in the deep layers of the primary somatosensory cortex. SWDs propagate to the mostly GABAergic nucleus reticularis thalami (NRT) and the somatosensory thalamic nuclei that project back to the cortex, leading to the typical generalized spike and wave oscillations. Given their shared anatomical basis, SWDs have been originally considered the pathological transition of 11-16 Hz bursts of neural oscillatory activity (the so-called sleep spindles) occurring during Non-Rapid Eye Movement (NREM) sleep, but more recent research revealed fundamental functional differences between sleep spindles and SWDs, suggesting the latter could be more closely related to the slow (<1 Hz) oscillations alternating active (Up) and silent (Down) cortical activity and concomitantly occurring during NREM. Indeed, several lines of evidence support the fact that SWDs impair sleep architecture as well as sleep/wake cycles and sleep pressure, which, in turn, affect seizure circadian frequency and distribution. Given the accumulating evidence on the role of astroglia in the field of epilepsy in the modulation of excitation and inhibition in the brain as well as on the development of aberrant synchronous network activity, we aim at pointing at putative contributions of astrocytes to the physiology of slow-wave sleep and to the pathology of SWDs. Particularly, we will address the astroglial functions known to be involved in the control of network excitability and synchronicity and so far mainly addressed in the context of convulsive seizures, namely (i) interstitial fluid homeostasis, (ii) K+ clearance and neurotransmitter uptake from the extracellular space and the synaptic cleft, (iii) gap junction mechanical and functional coupling as well as hemichannel function, (iv) gliotransmission, (v) astroglial Ca2+ signaling and downstream effectors, (vi) reactive astrogliosis and cytokine release.
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Affiliation(s)
- Davide Gobbo
- Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany
| | - Anja Scheller
- Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany
| | - Frank Kirchhoff
- Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany
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34
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Prashanth G, Vastrad B, Tengli A, Vastrad C, Kotturshetti I. Investigation of candidate genes and mechanisms underlying obesity associated type 2 diabetes mellitus using bioinformatics analysis and screening of small drug molecules. BMC Endocr Disord 2021; 21:80. [PMID: 33902539 PMCID: PMC8074411 DOI: 10.1186/s12902-021-00718-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Accepted: 03/02/2021] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Obesity associated type 2 diabetes mellitus is a metabolic disorder ; however, the etiology of obesity associated type 2 diabetes mellitus remains largely unknown. There is an urgent need to further broaden the understanding of the molecular mechanism associated in obesity associated type 2 diabetes mellitus. METHODS To screen the differentially expressed genes (DEGs) that might play essential roles in obesity associated type 2 diabetes mellitus, the publicly available expression profiling by high throughput sequencing data (GSE143319) was downloaded and screened for DEGs. Then, Gene Ontology (GO) and REACTOME pathway enrichment analysis were performed. The protein - protein interaction network, miRNA - target genes regulatory network and TF-target gene regulatory network were constructed and analyzed for identification of hub and target genes. The hub genes were validated by receiver operating characteristic (ROC) curve analysis and RT- PCR analysis. Finally, a molecular docking study was performed on over expressed proteins to predict the target small drug molecules. RESULTS A total of 820 DEGs were identified between healthy obese and metabolically unhealthy obese, among 409 up regulated and 411 down regulated genes. The GO enrichment analysis results showed that these DEGs were significantly enriched in ion transmembrane transport, intrinsic component of plasma membrane, transferase activity, transferring phosphorus-containing groups, cell adhesion, integral component of plasma membrane and signaling receptor binding, whereas, the REACTOME pathway enrichment analysis results showed that these DEGs were significantly enriched in integration of energy metabolism and extracellular matrix organization. The hub genes CEBPD, TP73, ESR2, TAB1, MAP 3K5, FN1, UBD, RUNX1, PIK3R2 and TNF, which might play an essential role in obesity associated type 2 diabetes mellitus was further screened. CONCLUSIONS The present study could deepen the understanding of the molecular mechanism of obesity associated type 2 diabetes mellitus, which could be useful in developing therapeutic targets for obesity associated type 2 diabetes mellitus.
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Affiliation(s)
- G Prashanth
- Department of General Medicine, Basaveshwara Medical College, Chitradurga, Karnataka, 577501, India
| | - Basavaraj Vastrad
- Department of Biochemistry, Basaveshwar College of Pharmacy, Gadag, Karnataka, 582103, India
| | - Anandkumar Tengli
- Department of Pharmaceutical Chemistry, JSS College of Pharmacy, Mysuru and JSS Academy of Higher Education & Research, Mysuru, Karnataka, 570015, India
| | - Chanabasayya Vastrad
- Biostatistics and Bioinformatics, Chanabasava Nilaya, Bharthinagar, Dharwad, Karnataka, 580001, India.
| | - Iranna Kotturshetti
- Department of Ayurveda, Rajiv Gandhi Education Society`s Ayurvedic Medical College, Ron, Karnataka, 582209, India
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35
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Ryan RM, Ingram SL, Scimemi A. Regulation of Glutamate, GABA and Dopamine Transporter Uptake, Surface Mobility and Expression. Front Cell Neurosci 2021; 15:670346. [PMID: 33927596 PMCID: PMC8076567 DOI: 10.3389/fncel.2021.670346] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2021] [Accepted: 03/15/2021] [Indexed: 01/31/2023] Open
Abstract
Neurotransmitter transporters limit spillover between synapses and maintain the extracellular neurotransmitter concentration at low yet physiologically meaningful levels. They also exert a key role in providing precursors for neurotransmitter biosynthesis. In many cases, neurons and astrocytes contain a large intracellular pool of transporters that can be redistributed and stabilized in the plasma membrane following activation of different signaling pathways. This means that the uptake capacity of the brain neuropil for different neurotransmitters can be dynamically regulated over the course of minutes, as an indirect consequence of changes in neuronal activity, blood flow, cell-to-cell interactions, etc. Here we discuss recent advances in the mechanisms that control the cell membrane trafficking and biophysical properties of transporters for the excitatory, inhibitory and modulatory neurotransmitters glutamate, GABA, and dopamine.
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Affiliation(s)
- Renae M. Ryan
- School of Medical Sciences, Faculty of Medicine and Health, University of Sydney, Sydney, NSW, Australia
| | - Susan L. Ingram
- Department of Neurological Surgery, Oregon Health & Science University, Portland, OR, United States
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