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Johannesen KM, Tümer Z, Weckhuysen S, Barakat TS, Bayat A. Solving the unsolved genetic epilepsies: Current and future perspectives. Epilepsia 2023; 64:3143-3154. [PMID: 37750451 DOI: 10.1111/epi.17780] [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] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Revised: 09/21/2023] [Accepted: 09/22/2023] [Indexed: 09/27/2023]
Abstract
Many patients with epilepsy undergo exome or genome sequencing as part of a diagnostic workup; however, many remain genetically unsolved. There are various factors that account for negative results in exome/genome sequencing for patients with epilepsy: (1) the underlying cause is not genetic; (2) there is a complex polygenic explanation; (3) the illness is monogenic but the causative gene remains to be linked to a human disorder; (4) family segregation with reduced penetrance; (5) somatic mosaicism or the complexity of, for example, a structural rearrangement; or (6) limited knowledge or diagnostic tools that hinder the proper classification of a variant, resulting in its designation as a variant of unknown significance. The objective of this review is to outline some of the diagnostic options that lie beyond the exome/genome, and that might become clinically relevant within the foreseeable future. These options include: (1) re-analysis of older exome/genome data as knowledge increases or symptoms change; (2) looking for somatic mosaicism or long-read sequencing to detect low-complexity repeat variants or specific structural variants missed by traditional exome/genome sequencing; (3) exploration of the non-coding genome including disruption of topologically associated domains, long range non-coding RNA, or other regulatory elements; and finally (4) transcriptomics, DNA methylation signatures, and metabolomics as complementary diagnostic methods that may be used in the assessment of variants of unknown significance. Some of these tools are currently not integrated into standard diagnostic workup. However, it is reasonable to expect that they will become increasingly available and improve current diagnostic capabilities, thereby enabling precision diagnosis in patients who are currently undiagnosed.
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Affiliation(s)
- Katrine M Johannesen
- Department of Genetics, Copenhagen University Hospital, Copenhagen, Denmark
- Department of Epilepsy Genetics and Personalized Medicine, The Danish Epilepsy Center, Dianalund, Denmark
| | - Zeynep Tümer
- Department of Genetics, Copenhagen University Hospital, Copenhagen, Denmark
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Sarah Weckhuysen
- Applied and Translational Neurogenomics Group, VIB Centre for Molecular Neurology, Antwerp, Belgium
- Translational Neurosciences, Faculty of Medicine and Health Science, University of Antwerp, Antwerp, Belgium
- Department of Neurology, University Hospital Antwerp, Antwerp, Belgium
- μNEURO Research Centre of Excellence, University of Antwerp, Antwerp, Belgium
| | - Tahsin Stefan Barakat
- Department of Clinical Genetics, Erasmus MC University Medical Center, Rotterdam, The Netherlands
- Discovery Unit, Department of Clinical Genetics, Erasmus MC University Medical Center, Rotterdam, The Netherlands
- ENCORE Expertise Center for Neurodevelopmental Disorders, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Allan Bayat
- Department of Epilepsy Genetics and Personalized Medicine, The Danish Epilepsy Center, Dianalund, Denmark
- Department of Regional Health Research, University of Southern Denmark, Odense, Denmark
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
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Study of paediatric patients with the clinical and biochemical phenotype of glucose transporter type 1 deficiency syndrome. NEUROLOGÍA (ENGLISH EDITION) 2022; 37:91-100. [PMID: 35279228 DOI: 10.1016/j.nrleng.2018.10.023] [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: 08/13/2018] [Accepted: 10/30/2018] [Indexed: 11/20/2022] Open
Abstract
INTRODUCTION Glucose transporter type 1 (GLUT1) deficiency syndrome may present a range of phenotypes, including epilepsy, intellectual disability, and movement disorders. The majority of patients present low CSF glucose levels and/or defects in the SLC2A1 gene; however, some patients do not present low CSF glucose or SLC2A1 mutations, and may have other mutations in other genes with compatible phenotypes. AIMS We describe the clinical, biochemical, and genetic characteristics of the disease and perform a univariate analysis of a group of patients with clinical and biochemical phenotype of GLUT1 deficiency syndrome, with or without SLC2A1 mutations. MATERIAL AND METHODS The study included 13 patients meeting clinical and biochemical criteria for GLUT1 deficiency syndrome. SLC2A1 sequencing and multiplex ligation-dependent probe amplification were performed; exome sequencing was performed for patients with negative results. RESULTS Six patients presented the classic phenotype; 2 paroxysmal dyskinesia, 2 complex movement disorders, 2 early-onset absence seizures, and one presented drug-resistant childhood absence epilepsy. Six patients were positive for SLC2A1 mutations; in the other 5, another genetic defect was identified. No significant differences were observed between the 2 groups for age of onset, clinical presentation, microcephaly, intellectual disability, or response to ketogenic diet. Patients with SLC2A1 mutations presented more clinical changes in relation to diet (66.7%, vs 28.6% in the SLC2A1-negative group) and greater persistence of motor symptoms (66% vs 28.6%); these differences were not statistically significant. Significant differences were observed for CSF glucose level (34.5 vs 46mg/dL, P=.04) and CSF/serum glucose ratio (0.4 vs 0.48, P<.05). CONCLUSIONS GLUT1 deficiency syndrome may be caused by mutations to genes other than SLC2A1 in patients with compatible phenotype, low CSF glucose level, and good response to the ketogenic diet.
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Diagnostic and Clinical Manifestation Differences of Glucose Transporter Type 1 Deficiency Syndrome in a Family with SLC2A1 Gene Mutation. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:ijerph19063279. [PMID: 35328965 PMCID: PMC8950241 DOI: 10.3390/ijerph19063279] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 03/05/2022] [Accepted: 03/07/2022] [Indexed: 01/27/2023]
Abstract
Glucose transporter type 1 deficiency syndrome is a rare genetic disease that manifests neurological symptoms such as mental impairment or movement disorders, mostly seen in pediatric patients. Here, we highlight the main symptoms, diagnostic difficulties, and genetic correlations of this disease based on different clinical presentations between the members of a family carrying the same mutation. In this report, we studied siblings—a 5-year-old girl and a 6-year-old boy—who were admitted to a pediatric ward with various neurological symptoms. Different diagnostic procedures such as lumbar puncture, electroencephalography, and MRI of the brain were performed on these patients. Whole genome sequencing identified mutations in the SLC2A1 and GLUT1-DS genes, following which a ketogenic diet was implemented. This diet modification resulted in a good clinical response. Our case report reveals patients with the same genetic mutations having distinctive clinical manifestations.
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Jiménez Legido M, Cortés Ledesma C, Bernardino Cuesta B, López Marín L, Cantarín Extremera V, Pérez-Cerdá C, Pérez González B, López Martín E, González Gutiérrez-Solana L. Study of paediatric patients with the clinical and biochemical phenotype of glucose transporter type 1 deficiency syndrome. Neurologia 2022; 37:91-100. [PMID: 31047728 DOI: 10.1016/j.nrl.2018.10.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Revised: 10/16/2018] [Accepted: 10/30/2018] [Indexed: 02/06/2023] Open
Abstract
INTRODUCTION Glucose transporter type 1 (GLUT1) deficiency syndrome may present a range of phenotypes, including epilepsy, intellectual disability, and movement disorders. The majority of patients present low CSF glucose levels and/or defects in the SLC2A1 gene; however, some patients do not present low CSF glucose or SLC2A1 mutations, and may have other mutations in other genes with compatible phenotypes. AIMS We describe the clinical, biochemical, and genetic characteristics of the disease and perform a univariate analysis of a group of patients with clinical and biochemical phenotype of GLUT1 deficiency syndrome, with or without SLC2A1 mutations. MATERIAL AND METHODS The study included 13 patients meeting clinical and biochemical criteria for GLUT1 deficiency syndrome. SLC2A1 sequencing and multiplex ligation-dependent probe amplification were performed; exome sequencing was performed for patients with negative results. RESULTS Six patients presented the classic phenotype; 2 paroxysmal dyskinesia, 2 complex movement disorders, 2 early-onset absence seizures, and one presented drug-resistant childhood absence epilepsy. Six patients were positive for SLC2A1 mutations; in the other 5, another genetic defect was identified. No significant differences were observed between the 2 groups for age of onset, clinical presentation, microcephaly, intellectual disability, or response to ketogenic diet. Patients with SLC2A1 mutations presented more clinical changes in relation to diet (66.7% vs. 28.6% in the SLC2A1-negative group) and greater persistence of motor symptoms (66% vs. 28.6%); these differences were not statistically significant. Significant differences were observed for CSF glucose level (34.5 vs. 46mg/dL, P=.04) and CSF/serum glucose ratio (0.4 vs. 0.48, P<.05). CONCLUSIONS GLUT1 deficiency syndrome may be caused by mutations to genes other than SLC2A1 in patients with compatible phenotype, low CSF glucose level, and good response to the ketogenic diet.
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Affiliation(s)
- M Jiménez Legido
- Sección de Neuropediatría, Hospital Infantil Universitario Niño Jesús, Madrid, España.
| | - C Cortés Ledesma
- Sección de Neuropediatría, Hospital Infantil Universitario Niño Jesús, Madrid, España
| | - B Bernardino Cuesta
- Sección de Neuropediatría, Hospital Infantil Universitario Niño Jesús, Madrid, España
| | - L López Marín
- Sección de Neuropediatría, Hospital Infantil Universitario Niño Jesús, Madrid, España; Grupo Clínico Vinculado a CIBERER (GCV6)
| | - V Cantarín Extremera
- Sección de Neuropediatría, Hospital Infantil Universitario Niño Jesús, Madrid, España; Grupo Clínico Vinculado a CIBERER (GCV6)
| | - C Pérez-Cerdá
- Centro de Diagnóstico de Enfermedades Moleculares (CEDEM), Madrid, España
| | - B Pérez González
- Centro de Diagnóstico de Enfermedades Moleculares (CEDEM), Madrid, España
| | - E López Martín
- Instituto de Investigación de Enfermedades Raras (IIER) & Centro de Investigación Biomédica en Red para Enfermedades Raras (CIBERER), Instituto de Salud Carlos III, Madrid, España
| | - L González Gutiérrez-Solana
- Sección de Neuropediatría, Hospital Infantil Universitario Niño Jesús, Madrid, España; Grupo Clínico Vinculado a CIBERER (GCV6)
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Gavrilovici C, Rho JM. Metabolic epilepsies amenable to ketogenic therapies: Indications, contraindications, and underlying mechanisms. J Inherit Metab Dis 2021; 44:42-53. [PMID: 32654164 DOI: 10.1002/jimd.12283] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 07/04/2020] [Accepted: 07/07/2020] [Indexed: 12/20/2022]
Abstract
Metabolic epilepsies arise in the context of rare inborn errors of metabolism (IEM), notably glucose transporter type 1 deficiency syndrome, succinic semialdehyde dehydrogenase deficiency, pyruvate dehydrogenase complex deficiency, nonketotic hyperglycinemia, and mitochondrial cytopathies. A common feature of these disorders is impaired bioenergetics, which through incompletely defined mechanisms result in a wide spectrum of neurological symptoms, such as epileptic seizures, developmental delay, and movement disorders. The ketogenic diet (KD) has been successfully utilized to treat such conditions to varying degrees. While the mechanisms underlying the clinical efficacy of the KD in IEM remain unclear, it is likely that the proposed heterogeneous targets influenced by the KD work in concert to rectify or ameliorate the downstream negative consequences of genetic mutations affecting key metabolic enzymes and substrates-such as oxidative stress and cell death. These beneficial effects can be broadly grouped into restoration of impaired bioenergetics and synaptic dysfunction, improved redox homeostasis, anti-inflammatory, and epigenetic activity. Hence, it is conceivable that the KD might prove useful in other metabolic disorders that present with epileptic seizures. At the same time, however, there are notable contraindications to KD use, such as fatty acid oxidation disorders. Clearly, more research is needed to better characterize those metabolic epilepsies that would be amenable to ketogenic therapies, both experimentally and clinically. In the end, the expanded knowledge base will be critical to designing metabolism-based treatments that can afford greater clinical efficacy and tolerability compared to current KD approaches, and improved long-term outcomes for patients.
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Affiliation(s)
- Cezar Gavrilovici
- Departments of Neurosciences and Pediatrics, University of California San Diego, Rady Children's Hospital, San Diego, California, USA
| | - Jong M Rho
- Departments of Neurosciences and Pediatrics, University of California San Diego, Rady Children's Hospital, San Diego, California, USA
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Takahashi S, Tanaka R, Takeguchi R, Kuroda M, Akaba Y, Ito Y. The role of molecular analysis of SLC2A1 in the diagnostic workup of glucose transporter 1 deficiency syndrome. J Neurol Sci 2020; 416:117041. [PMID: 32712428 DOI: 10.1016/j.jns.2020.117041] [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: 05/22/2020] [Revised: 06/24/2020] [Accepted: 07/13/2020] [Indexed: 10/23/2022]
Abstract
The study aimed to investigate the role of molecular analysis of SLC2A1 in the diagnostic workup of glucose transporter 1 deficiency syndrome (Glut1DS). During 2006-2020, we received 100 requests for SLC2A1 variant analysis of patients clinically suspected for Glut1DS. Pathogenic variants were detected in 37 patients, among whom 11 were familial cases. Most patients presented with epilepsy (n = 31; 84%), movement disorders (MD) (n = 28; 76%), and intellectual disabilities (ID) (n = 29; 78%). Moreover, paroxysmal dyskinesias (PD) (n = 10; 27%) were more frequently seen in familial cases (55%) than in sporadic cases (15%) (p < .05). The Glut1DS patients with ID typically had either epilepsy or MD. The presence of MD, particularly when associated with epilepsy or ID, indicated Glut1DS (p < .05). The cerebrospinal fluid (CSF) glucose levels were at or below the 10th percentile in all 32 SLC2A1-positive patients but only in 16 of 52 (31%) SLC2A1-negative patients (p < .05). Thus, CSF analysis is an essential tool in the diagnostic workup of Glut1DS. SLC2A1 molecular analysis should be performed in patients with a family history of Glut1DS or with at least one of the following clinical features, such as epilepsy, MD, and PD with or without ID, and low CSF glucose level. This would help in precise molecular diagnosis of the disease and facilitate effective treatment and appropriate genetic counseling.
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Affiliation(s)
- Satoru Takahashi
- Department of Pediatrics, Asahikawa Medical University, 2-1-1-1 Midorigaoka-Higashi, Asahikawa, Hokkaido 078-8510, Japan.
| | - Ryosuke Tanaka
- Department of Pediatrics, Asahikawa Medical University, 2-1-1-1 Midorigaoka-Higashi, Asahikawa, Hokkaido 078-8510, Japan
| | - Ryo Takeguchi
- Department of Pediatrics, Asahikawa Medical University, 2-1-1-1 Midorigaoka-Higashi, Asahikawa, Hokkaido 078-8510, Japan
| | - Mami Kuroda
- Department of Pediatrics, Asahikawa Medical University, 2-1-1-1 Midorigaoka-Higashi, Asahikawa, Hokkaido 078-8510, Japan
| | - Yuichi Akaba
- Department of Pediatrics, Asahikawa Medical University, 2-1-1-1 Midorigaoka-Higashi, Asahikawa, Hokkaido 078-8510, Japan
| | - Yasushi Ito
- Department of Pediatrics, Tokyo Women's Medical University, 8-1 Kawada-cho, Shinjuku-ku, Tokyo 162-8666, Japan
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Glucose transporters in brain in health and disease. Pflugers Arch 2020; 472:1299-1343. [PMID: 32789766 PMCID: PMC7462931 DOI: 10.1007/s00424-020-02441-x] [Citation(s) in RCA: 216] [Impact Index Per Article: 54.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 07/20/2020] [Accepted: 07/24/2020] [Indexed: 12/15/2022]
Abstract
Energy demand of neurons in brain that is covered by glucose supply from the blood is ensured by glucose transporters in capillaries and brain cells. In brain, the facilitative diffusion glucose transporters GLUT1-6 and GLUT8, and the Na+-d-glucose cotransporters SGLT1 are expressed. The glucose transporters mediate uptake of d-glucose across the blood-brain barrier and delivery of d-glucose to astrocytes and neurons. They are critically involved in regulatory adaptations to varying energy demands in response to differing neuronal activities and glucose supply. In this review, a comprehensive overview about verified and proposed roles of cerebral glucose transporters during health and diseases is presented. Our current knowledge is mainly based on experiments performed in rodents. First, the functional properties of human glucose transporters expressed in brain and their cerebral locations are described. Thereafter, proposed physiological functions of GLUT1, GLUT2, GLUT3, GLUT4, and SGLT1 for energy supply to neurons, glucose sensing, central regulation of glucohomeostasis, and feeding behavior are compiled, and their roles in learning and memory formation are discussed. In addition, diseases are described in which functional changes of cerebral glucose transporters are relevant. These are GLUT1 deficiency syndrome (GLUT1-SD), diabetes mellitus, Alzheimer’s disease (AD), stroke, and traumatic brain injury (TBI). GLUT1-SD is caused by defect mutations in GLUT1. Diabetes and AD are associated with changed expression of glucose transporters in brain, and transporter-related energy deficiency of neurons may contribute to pathogenesis of AD. Stroke and TBI are associated with changes of glucose transporter expression that influence clinical outcome.
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Liu J, Cai C, Wang Y, Liu Y, Huang L, Tian T, Yao Y, Wei J, Chen R, Zhang K, Liu B, Qian K. A Biomimetic Plasmonic Nanoreactor for Reliable Metabolite Detection. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2020; 7:1903730. [PMID: 32440487 PMCID: PMC7237842 DOI: 10.1002/advs.201903730] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2019] [Revised: 01/30/2020] [Accepted: 02/17/2020] [Indexed: 05/20/2023]
Abstract
Reliable monitoring of metabolites in biofluids is critical for diagnosis, treatment, and long-term management of various diseases. Although widely used, existing enzymatic metabolite assays face challenges in clinical practice primarily due to the susceptibility of enzyme activity to external conditions and the low sensitivity of sensing strategies. Inspired by the micro/nanoscale confined catalytic environment in living cells, the coencapsulation of oxidoreductase and metal nanoparticles within the nanopores of macroporous silica foams to fabricate all-in-one bio-nanoreactors is reported herein for use in surface-enhanced Raman scattering (SERS)-based metabolic assays. The enhancement of catalytical activity and stability of enzyme against high temperatures, long-time storage or proteolytic agents are demonstrated. The nanoreactors recognize and catalyze oxidation of the metabolite, and provide ratiometric SERS response in the presence of the enzymatic by-product H2O2, enabling sensitive metabolite quantification in a "sample in and answer out" manner. The nanoreactor makes any oxidoreductase-responsible metabolite a candidate for quantitative SERS sensing, as shown for glucose and lactate. Glucose levels of patients with bacterial infection are accurately analyzed with only 20 µL of cerebrospinal fluids, indicating the potential application of the nanoreactor in vitro clinical testing.
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Affiliation(s)
- Jiangang Liu
- Department of NeurosurgeryShanghai Children's HospitalMed‐X Research Institute and School of Biomedical EngineeringShanghai Jiao Tong UniversityShanghai200062China
| | - Chenlei Cai
- Department of Medical OncologyShanghai Pulmonary HospitalTongji University School of MedicineShanghai200433China
| | - Yuning Wang
- Department of ChemistryInstitutes of Biomedical Sciences and State Key Lab of Molecular Engineering of PolymersFudan UniversityShanghai200438China
| | - Yu Liu
- Department of NeurosurgeryShanghai Children's HospitalMed‐X Research Institute and School of Biomedical EngineeringShanghai Jiao Tong UniversityShanghai200062China
| | - Lin Huang
- Department of NeurosurgeryShanghai Children's HospitalMed‐X Research Institute and School of Biomedical EngineeringShanghai Jiao Tong UniversityShanghai200062China
| | - Tongtong Tian
- Department of ChemistryInstitutes of Biomedical Sciences and State Key Lab of Molecular Engineering of PolymersFudan UniversityShanghai200438China
| | - Yuanyuan Yao
- Department of ChemistryInstitutes of Biomedical Sciences and State Key Lab of Molecular Engineering of PolymersFudan UniversityShanghai200438China
| | - Jia Wei
- Department of NeurosurgeryShanghai Children's HospitalMed‐X Research Institute and School of Biomedical EngineeringShanghai Jiao Tong UniversityShanghai200062China
| | - Ruoping Chen
- Department of NeurosurgeryShanghai Children's HospitalMed‐X Research Institute and School of Biomedical EngineeringShanghai Jiao Tong UniversityShanghai200062China
| | - Kun Zhang
- Department of NeurosurgeryShanghai Children's HospitalMed‐X Research Institute and School of Biomedical EngineeringShanghai Jiao Tong UniversityShanghai200062China
| | - Baohong Liu
- Department of ChemistryInstitutes of Biomedical Sciences and State Key Lab of Molecular Engineering of PolymersFudan UniversityShanghai200438China
| | - Kun Qian
- Department of NeurosurgeryShanghai Children's HospitalMed‐X Research Institute and School of Biomedical EngineeringShanghai Jiao Tong UniversityShanghai200062China
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Language regression, hemichorea and focal subclinical seizures in a 6-year-old girl with GLUT-1 deficiency. Epilepsy Behav Rep 2020; 14:100340. [PMID: 32637909 PMCID: PMC7328258 DOI: 10.1016/j.ebr.2019.100340] [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: 05/03/2019] [Revised: 10/03/2019] [Accepted: 10/12/2019] [Indexed: 11/28/2022] Open
Abstract
A 6 year old girl with progressive speech difficulties, new abnormal movements, olfactory hallucinations Choreiform movement of her right hemibody along with her face and tongue Seizures were noted during sleep without clinical correlate, progressing to awake subclinical seizures
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Tang M, Park SH, De Vivo DC, Monani UR. Therapeutic strategies for glucose transporter 1 deficiency syndrome. Ann Clin Transl Neurol 2019; 6:1923-1932. [PMID: 31464092 PMCID: PMC6764625 DOI: 10.1002/acn3.50881] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Revised: 08/08/2019] [Accepted: 08/10/2019] [Indexed: 01/01/2023] Open
Abstract
Proper development and function of the mammalian brain is critically dependent on a steady supply of its chief energy source, glucose. Such supply is mediated by the glucose transporter 1 (Glut1) protein. Paucity of the protein stemming from mutations in the associated SLC2A1 gene deprives the brain of glucose and triggers the infantile‐onset neurodevelopmental disorder, Glut1 deficiency syndrome (Glut1 DS). Considering the monogenic nature of Glut1 DS, the disease is relatively straightforward to model and thus study. Accordingly, Glut1 DS serves as a convenient paradigm to investigate the more general cellular and molecular consequences of brain energy failure. Here, we review how Glut1 DS models have informed the biology of a prototypical brain energy failure syndrome, how these models are facilitating the development of promising new treatments for the human disease, and how important insights might emerge from the study of Glut1 DS to illuminate the myriad conditions involving the Glut1 protein.
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Affiliation(s)
- Maoxue Tang
- Department of Pathology & Cell Biology, Columbia University Medical Center, New York, New York, 10032.,Center for Motor Neuron Biology and Disease, Columbia University Medical Center, New York, New York, 10032
| | - Sarah H Park
- Center for Motor Neuron Biology and Disease, Columbia University Medical Center, New York, New York, 10032.,Department of Neurology, Columbia University Medical Center, New York, New York, 10032
| | - Darryl C De Vivo
- Center for Motor Neuron Biology and Disease, Columbia University Medical Center, New York, New York, 10032.,Department of Neurology, Columbia University Medical Center, New York, New York, 10032
| | - Umrao R Monani
- Department of Pathology & Cell Biology, Columbia University Medical Center, New York, New York, 10032.,Center for Motor Neuron Biology and Disease, Columbia University Medical Center, New York, New York, 10032.,Department of Neurology, Columbia University Medical Center, New York, New York, 10032
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Perenthaler E, Yousefi S, Niggl E, Barakat TS. Beyond the Exome: The Non-coding Genome and Enhancers in Neurodevelopmental Disorders and Malformations of Cortical Development. Front Cell Neurosci 2019; 13:352. [PMID: 31417368 PMCID: PMC6685065 DOI: 10.3389/fncel.2019.00352] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Accepted: 07/16/2019] [Indexed: 12/22/2022] Open
Abstract
The development of the human cerebral cortex is a complex and dynamic process, in which neural stem cell proliferation, neuronal migration, and post-migratory neuronal organization need to occur in a well-organized fashion. Alterations at any of these crucial stages can result in malformations of cortical development (MCDs), a group of genetically heterogeneous neurodevelopmental disorders that present with developmental delay, intellectual disability and epilepsy. Recent progress in genetic technologies, such as next generation sequencing, most often focusing on all protein-coding exons (e.g., whole exome sequencing), allowed the discovery of more than a 100 genes associated with various types of MCDs. Although this has considerably increased the diagnostic yield, most MCD cases remain unexplained. As Whole Exome Sequencing investigates only a minor part of the human genome (1–2%), it is likely that patients, in which no disease-causing mutation has been identified, could harbor mutations in genomic regions beyond the exome. Even though functional annotation of non-coding regions is still lagging behind that of protein-coding genes, tremendous progress has been made in the field of gene regulation. One group of non-coding regulatory regions are enhancers, which can be distantly located upstream or downstream of genes and which can mediate temporal and tissue-specific transcriptional control via long-distance interactions with promoter regions. Although some examples exist in literature that link alterations of enhancers to genetic disorders, a widespread appreciation of the putative roles of these sequences in MCDs is still lacking. Here, we summarize the current state of knowledge on cis-regulatory regions and discuss novel technologies such as massively-parallel reporter assay systems, CRISPR-Cas9-based screens and computational approaches that help to further elucidate the emerging role of the non-coding genome in disease. Moreover, we discuss existing literature on mutations or copy number alterations of regulatory regions involved in brain development. We foresee that the future implementation of the knowledge obtained through ongoing gene regulation studies will benefit patients and will provide an explanation to part of the missing heritability of MCDs and other genetic disorders.
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Affiliation(s)
- Elena Perenthaler
- Department of Clinical Genetics, Erasmus MC - University Medical Center, Rotterdam, Netherlands
| | - Soheil Yousefi
- Department of Clinical Genetics, Erasmus MC - University Medical Center, Rotterdam, Netherlands
| | - Eva Niggl
- 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
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Wei Z, Wang L, Deng Y. Treatment of myoclonic-atonic epilepsy caused by SLC2A1 de novo mutation with ketogenic diet: A case report. Medicine (Baltimore) 2019; 98:e15428. [PMID: 31045803 PMCID: PMC6504322 DOI: 10.1097/md.0000000000015428] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
RATIONALE The SLC2A1 gene encodes glucose transporter 1 on blood-brain barrier, which plays an important role in the energy supply for neurons. Mutations in SLC2A1 gene can cause many clinical syndromes, including glucose transporter type 1 deficiency syndrome and many types of epilepsy syndromes such as childhood absence epilepsy and myoclonic-atonic epilepsy, etc. Ketogenic diet has been proved to be very effective on those cases. Clinically, SLC2A1 gene mutations are quite rare. PATIENT CONCERNS Repeated unconsciousness and bilateral limb weakness lasted for 3 years. DIAGNOSES Myoclonic-atonic epilepsy. LESSONS After taking whole exome sequencing, we found out that there is a de novo insertion mutation in the patient's SLC2A1 gene, leading to frameshift. As a result, ketogenic diet (2:1, 4 times a day) was used as the treatment. As for the patient, total calories intake per day was controlled at 1190 kcal. The calories per kg per day were 66.11 kcal/kg. The amount of ketone bodies was controlled at 2 to 3 mmol/L and the concentration of plasma glucose was controlled at 4 to 5 mmol/L. OUTCOMES After the launch of ketogenic diet, the patient has been seizure free for nearly a year and stopped all his antiepileptic drugs. CONCLUSION Our case suggests that gene examination is very important part of the diagnosis of epilepsy etiology and epilepsy syndromes. Ketogenic diet should be considered as the first line therapy with SLC2A1 gene mutations.
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Koch H, Weber YG. The glucose transporter type 1 (Glut1) syndromes. Epilepsy Behav 2019; 91:90-93. [PMID: 30076047 DOI: 10.1016/j.yebeh.2018.06.010] [Citation(s) in RCA: 78] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Revised: 06/06/2018] [Accepted: 06/06/2018] [Indexed: 01/15/2023]
Abstract
The glucose transporter type 1 (Glut1) is the most important energy carrier of the brain across the blood-brain barrier. In the early nineties, the first genetic defect of Glut1 was described and known as the Glut1 deficiency syndrome (Glut1-DS). It is characterized by early infantile seizures, developmental delay, microcephaly, and ataxia. Recently, milder variants have also been described. The clinical picture of Glut1 defects and the understanding of the pathophysiology of this disease have significantly grown. A special form of transient movement disorders, the paroxysmal exertion-induced dyskinesia (PED), absence epilepsies particularly with an early onset absence epilepsy (EOAE) and childhood absence epilepsy (CAE), myoclonic astatic epilepsy (MAE), episodic choreoathetosis and spasticity (CSE), and focal epilepsy can be based on a Glut1 defect. Despite the rarity of these diseases, the Glut1 syndromes are of high clinical interest since a very effective therapy, the ketogenic diet, can improve or reverse symptoms especially if it is started as early as possible. The present article summarizes the clinical features of Glut1 syndromes and discusses the underlying genetic mutations, including the available data on functional tests as well as the genotype-phenotype correlations. This article is part of the Special Issue "Individualized Epilepsy Management: Medicines, Surgery and Beyond".
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Affiliation(s)
- Henner Koch
- Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Yvonne G Weber
- Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany.
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Cowley MJ, Liu YC, Oliver KL, Carvill G, Myers CT, Gayevskiy V, Delatycki M, Vlaskamp DRM, Zhu Y, Mefford H, Buckley MF, Bahlo M, Scheffer IE, Dinger ME, Roscioli T. Reanalysis and optimisation of bioinformatic pipelines is critical for mutation detection. Hum Mutat 2019; 40:374-379. [PMID: 30556619 PMCID: PMC6492103 DOI: 10.1002/humu.23699] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Revised: 12/10/2018] [Accepted: 12/13/2018] [Indexed: 12/30/2022]
Abstract
Rapid advances in genomic technologies have facilitated the identification pathogenic variants causing human disease. We report siblings with developmental and epileptic encephalopathy due to a novel, shared heterozygous pathogenic 13 bp duplication in SYNGAP1 (c.435_447dup, p.(L150Vfs*6)) that was identified by whole genome sequencing (WGS). The pathogenic variant had escaped earlier detection via two methodologies: whole exome sequencing and high-depth targeted sequencing. Both technologies had produced reads carrying the variant, however, they were either not aligned due to the size of the insertion or aligned to multiple major histocompatibility complex (MHC) regions in the hg19 reference genome, making the critical reads unavailable for variant calling. The WGS pipeline followed different protocols, including alignment of reads to the GRCh37 reference genome, which lacks the additional MHC contigs. Our findings highlight the benefit of using orthogonal clinical bioinformatic pipelines and all relevant inheritance patterns to re-analyze genomic data in undiagnosed patients.
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Affiliation(s)
- Mark J Cowley
- Kinghorn Centre for Clinical Genomics, Garvan Institute of Medical Research, Darlinghurst, NSW, Australia.,St Vincent's Clinical School, University of New South Wales, Darlinghurst, Australia
| | - Yu-Chi Liu
- Population Health and Immunity Division, Walter and Eliza Hall Institute, Melbourne, Australia.,Epilepsy Research Centre, Department of Medicine, University of Melbourne, Austin Health, Heidelberg, Australia.,Department of Medical Biology, The University of Melbourne, Parkville, Victoria, Australia
| | - Karen L Oliver
- Population Health and Immunity Division, Walter and Eliza Hall Institute, Melbourne, Australia.,Epilepsy Research Centre, Department of Medicine, University of Melbourne, Austin Health, Heidelberg, Australia
| | - Gemma Carvill
- Ken and Ruth Davee Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL
| | - Candace T Myers
- Department of Pediatrics, University of Washington, Seattle, WA
| | - Velimir Gayevskiy
- Kinghorn Centre for Clinical Genomics, Garvan Institute of Medical Research, Darlinghurst, NSW, Australia
| | | | - Danique R M Vlaskamp
- Epilepsy Research Centre, Department of Medicine, University of Melbourne, Austin Health, Heidelberg, Australia
| | - Ying Zhu
- Department of Medical Genetics, Royal North Shore Hospital, St Leonards, Australia
| | - Heather Mefford
- Department of Pediatrics, University of Washington, Seattle, WA
| | | | - Melanie Bahlo
- Population Health and Immunity Division, Walter and Eliza Hall Institute, Melbourne, Australia.,Department of Medical Biology, The University of Melbourne, Parkville, Victoria, Australia
| | - Ingrid E Scheffer
- Epilepsy Research Centre, Department of Medicine, University of Melbourne, Austin Health, Heidelberg, Australia.,Florey Institute, Melbourne, Australia.,Department of Paediatrics, University of Melbourne, Royal Children's Hospital, Parkville, Australia
| | - Marcel E Dinger
- Kinghorn Centre for Clinical Genomics, Garvan Institute of Medical Research, Darlinghurst, NSW, Australia.,St Vincent's Clinical School, University of New South Wales, Darlinghurst, Australia
| | - Tony Roscioli
- Centre for Clinical Genetics, Sydney Children's Hospital, Randwick, Australia.,Prince of Wales Clinical School, University of New South Wales, Sydney, Australia.,Neuroscience Research Australia, University of New South Wales, Randwick, Sydney, Australia
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Boltshauser E, Weber KP. Laboratory investigations. HANDBOOK OF CLINICAL NEUROLOGY 2018; 154:287-298. [PMID: 29903445 DOI: 10.1016/b978-0-444-63956-1.00017-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
This chapter deals with chemical and hematologic investigations which are often considered in the diagnostic workup of subacute to chronic cerebellar ataxias. Relevant investigations in blood (serum, plasma), urine, and cerebrospinal fluid are discussed. Particular attention is paid to early diagnosis of treatable metabolic ataxias (such as abetalipoproteinemia, coenzyme Q10 deficiency, cerebrotendinous xanthomatosis, glucose transporter type 1 deficiency, Refsum disease, and vitamin E deficiency), but autoimmune ataxias, other vitamin deficiencies, and endocrine disorders should also be kept in mind. Adequate interpretation of test results has to consider age-specific reference values. The selection of investigations should mainly be driven by the overall clinical context, considering gender, history, age, and mode of presentation, cerebellar and other neurologic as well as extraneurologic findings.
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Affiliation(s)
- Eugen Boltshauser
- Department of Pediatric Neurology, University Children's Hospital, University of Zurich, Zurich, Switzerland; Departments of Neurology and Ophthalmology, University Hospital Zurich, University of Zurich, Switzerland.
| | - Konrad P Weber
- Department of Pediatric Neurology, University Children's Hospital, University of Zurich, Zurich, Switzerland; Departments of Neurology and Ophthalmology, University Hospital Zurich, University of Zurich, Switzerland
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Upstream SLC2A1 translation initiation causes GLUT1 deficiency syndrome. Eur J Hum Genet 2017; 25:771-774. [PMID: 28378819 DOI: 10.1038/ejhg.2017.45] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2016] [Revised: 01/26/2017] [Accepted: 02/28/2017] [Indexed: 11/08/2022] Open
Abstract
Glucose transporter type 1 deficiency syndrome (GLUT1DS) is a neurometabolic disorder with a complex phenotypic spectrum but simple biomarkers in cerebrospinal fluid. The disorder is caused by impaired glucose transport into the brain resulting from variants in SCL2A1. In 10% of GLUT1DS patients, a genetic diagnosis can not be made. Using whole-genome sequencing, we identified a de novo 5'-UTR variant in SLC2A1, generating a novel translation initiation codon, severely compromising SLC2A1 function. This finding expands our understanding of the disease mechanisms underlying GLUT1DS and encourages further in-depth analysis of SLC2A1 non-coding regions in patients without variants in the coding region.
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Van Karnebeek CDM. GLUT1 deficiency: progress in unraveling its genetic basis. Dev Med Child Neurol 2016; 58:1210-1211. [PMID: 27468989 DOI: 10.1111/dmcn.13220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Clara D M Van Karnebeek
- Department of Pediatrics, BC Children's Hospital, Centre for Molecular Medicine and Therapeutics, University of British Columbia, Vancouver, Canada
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