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Leung KY, Santos C, De Castro SCP, Diaz DG, Copp AJ, Waddington S, Greene NDE. AAV-mediated expression of mouse or human GLDC normalises metabolic biomarkers in a GLDC-deficient mouse model of Non-Ketotic Hyperglycinemia. Mol Genet Metab 2024; 142:108496. [PMID: 38761651 DOI: 10.1016/j.ymgme.2024.108496] [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: 02/14/2024] [Revised: 04/04/2024] [Accepted: 05/13/2024] [Indexed: 05/20/2024]
Abstract
Non-Ketotic Hyperglycinemia (NKH) is a rare inborn error of metabolism caused by impaired function of the glycine cleavage system (GCS) and characterised by accumulation of glycine in body fluids and tissues. NKH is an autosomal recessive condition and the majority of affected individuals carry mutations in GLDC (glycine decarboxylase). Current treatments for NKH have limited effect and are not curative. As a monogenic condition with known genetic causation, NKH is potentially amenable to gene therapy. An AAV9-based expression vector was designed to target sites of GCS activity. Using a ubiquitous promoter to drive expression of a GFP reporter, transduction of liver and brain was confirmed following intra-venous and/or intra-cerebroventricular administration to neonatal mice. Using the same capsid and promoter with transgenes to express mouse or human GLDC, vectors were then tested in GLDC-deficient mice that provide a model of NKH. GLDC-deficient mice exhibited elevated plasma glycine concentration and accumulation of glycine in liver and brain tissues as previously observed. Moreover, the folate profile indicated suppression of folate one‑carbon metabolism (FOCM) in brain tissue, as found at embryonic stages, and reduced abundance of FOCM metabolites including betaine and choline. Neonatal administration of vector achieved reinstatement of GLDC mRNA and protein expression in GLDC-deficient mice. Treated GLDC-deficient mice showed significant lowering of plasma glycine, confirming functionality of vector expressed protein. AAV9-GLDC treatment also led to lowering of brain tissue glycine, and normalisation of the folate profile indicating restoration of glycine-derived one‑carbon supply. These findings support the hypothesis that AAV-mediated gene therapy may offer potential in treatment of NKH.
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Affiliation(s)
- Kit-Yi Leung
- Developmental Biology and Cancer Department, Great Ormond Street Institute of Child Health, University College London, London, UK
| | - Chloe Santos
- Developmental Biology and Cancer Department, Great Ormond Street Institute of Child Health, University College London, London, UK
| | - Sandra C P De Castro
- Developmental Biology and Cancer Department, Great Ormond Street Institute of Child Health, University College London, London, UK
| | - Diana Gold Diaz
- Developmental Biology and Cancer Department, Great Ormond Street Institute of Child Health, University College London, London, UK
| | - Andrew J Copp
- Developmental Biology and Cancer Department, Great Ormond Street Institute of Child Health, University College London, London, UK
| | - Simon Waddington
- EGA Institute for Women's Health, University College London, London, UK
| | - Nicholas D E Greene
- Developmental Biology and Cancer Department, Great Ormond Street Institute of Child Health, University College London, London, UK.
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2
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Leipnitz G, da Rosa JS, Wajner M. The Role of Excitotoxicity, Oxidative Stress and Bioenergetics Disruption in the Neuropathology of Nonketotic Hyperglycinemia. Neurotox Res 2024; 42:32. [PMID: 38949693 DOI: 10.1007/s12640-024-00711-5] [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: 01/16/2024] [Revised: 06/11/2024] [Accepted: 06/20/2024] [Indexed: 07/02/2024]
Abstract
Nonketotic hyperglycinemia (NKH) is an inherited disorder of amino acid metabolism biochemically characterized by the accumulation of glycine (Gly) predominantly in the brain. Affected patients usually manifest with neurological symptoms including hypotonia, seizures, epilepsy, lethargy, and coma, the pathophysiology of which is still not completely understood. Treatment is limited and based on lowering Gly levels aiming to reduce overstimulation of N-methyl-D-aspartate (NMDA) receptors. Mounting in vitro and in vivo animal and human evidence have recently suggested that excitotoxicity, oxidative stress, and bioenergetics disruption induced by Gly are relevant mechanisms involved in the neuropathology of NKH. This brief review gives emphasis to the deleterious effects of Gly in the brain of patients and animal models of NKH that may offer perspectives for the development of novel adjuvant treatments for this disorder.
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Affiliation(s)
- Guilhian Leipnitz
- Programa de Pós-Graduação em Ciências Biológicas: Bioquímica, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2600-Anexo, Porto Alegre, RS, 90035-003, Brazil.
- Programa de Pós-Graduação em Ciências Biológicas: Fisiologia, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2600-Anexo, Porto Alegre, RS, CEP 90035-003, Brazil.
| | - Jaqueline Santana da Rosa
- Programa de Pós-Graduação em Ciências Biológicas: Bioquímica, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2600-Anexo, Porto Alegre, RS, 90035-003, Brazil
| | - Moacir Wajner
- Programa de Pós-Graduação em Ciências Biológicas: Bioquímica, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2600-Anexo, Porto Alegre, RS, 90035-003, Brazil
- Programa de Pós-Graduação em Ciências Biológicas: Fisiologia, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2600-Anexo, Porto Alegre, RS, CEP 90035-003, Brazil
- Serviço de Genética Médica, Hospital de Clínicas de Porto Alegre, Rua Ramiro Barcelos, 2350, Porto Alegre, 90035-903, RS, Brazil
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Swanson MA, Jiang H, Busquet N, Carlsen J, Brindley C, Benke TA, Van Hove RA, Friederich MW, MacLean KN, Mesches MH, Van Hove JLK. Deep postnatal phenotyping of a new mouse model of nonketotic hyperglycinemia. J Inherit Metab Dis 2024. [PMID: 38840294 DOI: 10.1002/jimd.12755] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2023] [Revised: 04/18/2024] [Accepted: 05/02/2024] [Indexed: 06/07/2024]
Abstract
Nonketotic hyperglycinemia due to deficient glycine cleavage enzyme activity causes a severe neonatal epileptic encephalopathy. Current therapies based on mitigating glycine excess have only limited impact. An animal model with postnatal phenotyping is needed to explore new therapeutic approaches. We developed a Gldc p.Ala394Val mutant model and bred it to congenic status in two colonies on C57Bl/6J (B6) and J129X1/SvJ (J129) backgrounds. Mutant mice had reduced P-protein and enzyme activity indicating a hypomorphic mutant. Glycine levels were increased in blood and brain regions, exacerbated by dietary glycine, with higher levels in female than male J129 mice. Birth defects were more prevalent in mutant B6 than J129 mice, and hydrocephalus was more frequent in B6 (40%) compared to J129 (none). The hydrocephalus rate was increased by postnatal glycine challenge in B6 mice, more so when delivered from the first neonatal week than from the fourth. Mutant mice had reduced weight gain following weaning until the eighth postnatal week, which was exacerbated by glycine loading. The electrographic spike rate was increased in mutant mice following glycine loading, but no seizures were observed. The alpha/delta band intensity ratio was decreased in the left cortex in female J129 mice, which were less active in an open field test and explored less in a Y-maze, suggesting an encephalopathic effect. Mutant mice showed no evidence of memory dysfunction. This partial recapitulation of human symptoms and biochemistry will facilitate the evaluation of new therapeutic approaches with an early postnatal time window likely most effective.
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Affiliation(s)
- Michael A Swanson
- Department of Pediatrics, Section of Clinical Genetics and Metabolism, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Hua Jiang
- Department of Pediatrics, Section of Clinical Genetics and Metabolism, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Nicolas Busquet
- NeuroTechnology Center, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
- Department of Neurology, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Jessica Carlsen
- NeuroTechnology Center, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Connie Brindley
- NeuroTechnology Center, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Tim A Benke
- Department of Pediatrics, Section of Pediatric Neurology, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Roxanne A Van Hove
- Department of Pediatrics, Section of Clinical Genetics and Metabolism, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Marisa W Friederich
- Department of Pediatrics, Section of Clinical Genetics and Metabolism, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Kenneth N MacLean
- Department of Pediatrics, Section of Clinical Genetics and Metabolism, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Michael H Mesches
- NeuroTechnology Center, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
- Department of Pediatrics, Section of Pediatric Neurology, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Johan L K Van Hove
- Department of Pediatrics, Section of Clinical Genetics and Metabolism, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
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Van Hirtum LDFM, Van Damme T, Van Hove JLK, Steyaert JG. The behavioral phenotype of children and adolescents with attenuated non-ketotic hyperglycinemia, intermediate to good subtype. Orphanet J Rare Dis 2024; 19:150. [PMID: 38589924 PMCID: PMC11003182 DOI: 10.1186/s13023-024-03172-3] [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: 11/28/2023] [Accepted: 03/30/2024] [Indexed: 04/10/2024] Open
Abstract
AIM We aim to describe the behavioral phenotype of children and adolescents with the good to intermediate attenuated form of non-ketotic hyperglycinemia (NKH) and to explore associations between the behavioral phenotype and age, sex, plasma glycine levels and drug treatment. METHOD Parents of children with attenuated NKH completed questionnaires assessing maladaptive behavior, adaptive behavior, social communication, speech/language development and motor development in addition to demographic and medical questions. RESULTS AND INTERPRETATION Twelve children, age 6 to 21y, functioned at mild to severe intellectual disability levels. Their speech/language development was in line with their developmental quotient. Relative to their intellectual functioning, their motor development and communication were weaker in comparison to their general development. Their adaptive behavior, however, appeared a relative strength. There was no evidence for autism spectrum disorder occurring more frequently than expected, rather social skills, except for communication, were rated as a relative strength. Maladaptive behaviors with ADHD-like characteristics were present in more than two thirds of children. Maladaptive behaviors were significantly related to female sex and to taking dextromethorphan, but no significant relation between plasma glycine levels and behavior was found. Future studies will need to evaluate causality in the observed relation between dextromethorphan use and maladaptive behaviors. Clinicians should reconsider the benefit of dextromethorphan when presented with disruptive behaviors in children with attenuated NKH.
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Affiliation(s)
- Liesbet D F M Van Hirtum
- Department of Child- and Adolescent Psychiatry, KU Leuven, Leuven, Belgium.
- Ankerpunt vzw, Leuven, Belgium.
| | - Tine Van Damme
- Department of Child Psychiatry, UPC Z.Org, Leuven, Belgium
- Department of Rehabilitation Sciences, KU Leuven, Leuven, Belgium
| | - Johan L K Van Hove
- Section of Clinical Genetics and Metabolism, Department of Pediatrics, University of Colorado, Aurora, Colorado, USA
| | - Jean G Steyaert
- Department of Child- and Adolescent Psychiatry, KU Leuven, Leuven, Belgium
- Leuven Autism Research Consortium, Leuven, Belgium
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Swanson MA, Jiang H, Busquet N, Carlsen J, Brindley C, Benke TA, Van Hove RA, Friederich MW, MacLean KN, Mesches MH, Van Hove JLK. Deep postnatal phenotyping of a new mouse model of nonketotic hyperglycinemia. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.26.586818. [PMID: 38586005 PMCID: PMC10996592 DOI: 10.1101/2024.03.26.586818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/09/2024]
Abstract
Nonketotic hyperglycinemia due to deficient glycine cleavage enzyme activity causes a severe neonatal epileptic encephalopathy. Current therapies based on mitigating glycine excess have only limited impact. An animal model with postnatal phenotyping is needed to explore new therapeutic approaches. We developed a Gldc p.Ala394Val mutant model and bred it to congenic status in 2 colonies on C57Bl/6J (B6) and J129X1/SvJ (J129) backgrounds. Mutant mice had reduced P-protein and enzyme activity indicating a hypomorphic mutant. Glycine levels were increased in blood and brain regions, exacerbated by dietary glycine, with higher levels in female than male J129 mice. Birth defects were more prevalent in mutant B6 than J129 mice, and hydrocephalus was more frequent in B6 (40%) compared to J129 (none). The hydrocephalus rate was increased by postnatal glycine challenge in B6 mice, more so when delivered from the first neonatal week than from the fourth. Mutant mice had reduced weight gain following weaning until the eighth postnatal week, which was exacerbated by glycine loading. The electrographic spike rate was increased in mutant mice following glycine loading, but no seizures were observed. The alpha/delta band intensity ratio was decreased in the left cortex in female J129 mice, which were less active in an open field test and explored less in a Y-maze, suggesting an encephalopathic effect. Mutant mice showed no evidence of memory dysfunction. This partial recapitulation of human symptoms and biochemistry will facilitate the evaluation of new therapeutic approaches with an early postnatal time window likely most effective. Take home message A mouse model of nonketotic hyperglycinemia is described that shows postnatal abnormalities in glycine levels, neural tube defects, body weight, electroencephalographic recordings, and in activity in young mice making it amenable for the evaluation of novel treatment interventions. Author contributions Study concept and design: JVH, MHM, NB, KNMAnimal study data: MAS, HJ, NB, MHM, JC, CBBiochemical and genetic studies: MAS, RAVH, MWFStatistical analysis: NB, JVHFirst draft writing: JVH, NB, MHMCritical rewriting: MAS, NB, MHM, TAB, JC, MWF, KNM, JVHFinal responsibility, guarantor, and communicating author: JVH. Competing interest statement The University of Colorado (JVH, MS, KNM, HJ) has the intention to file Intellectual property protection for certain biochemical treatments of NKH. Otherwise, the authors have stated that they had no interests that might be perceived as posing a conflict or bias to this subject matter. Funding support Financial support is acknowledged form the NKH Crusaders, Brodyn's Friends, Nora Jane Almany Foundation, the Dickens Family Foundation, the Lucas John Foundation, Les Petits Bourdons, Joseph's Fund, the Barnett Family, Maud & Vic Foundation, Lucy's BEElievers fund, Hope for NKH, Madi's Mission NKH fund, and from Dr. and Ms. Shaw, and the University of Colorado Foundation NKH research fund. The study was supported by a grant (CNS-X-19-103) from the University of Colorado School of Medicine and the Colorado Clinical Translational Science Institute, which is supported by NIH/NCATS Colorado CTSA Grant Number UL1 TR002535. Contents are the authors' sole responsibility and do not necessarily represent official NIH views. All funding sources had no role in the design or execution of the study, the interpretation of data, or the writing of the study. Ethics approval on Laboratory Animal Studies Mouse studies were carried out with approval from the Institutional Animal Care and Use Committee of the University of Colorado Anschutz Medical Campus (IACUC# 00413). Data sharing statement The data that support the findings of this study are available from the corresponding author upon reasonable request.
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Martelli F, Lin J, Mele S, Imlach W, Kanca O, Barlow CK, Paril J, Schittenhelm RB, Christodoulou J, Bellen HJ, Piper MDW, Johnson TK. Identifying potential dietary treatments for inherited metabolic disorders using Drosophila nutrigenomics. Cell Rep 2024; 43:113861. [PMID: 38416643 PMCID: PMC11037929 DOI: 10.1016/j.celrep.2024.113861] [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: 05/16/2023] [Revised: 12/09/2023] [Accepted: 02/08/2024] [Indexed: 03/01/2024] Open
Abstract
Inherited metabolic disorders are a group of genetic conditions that can cause severe neurological impairment and child mortality. Uniquely, these disorders respond to dietary treatment; however, this option remains largely unexplored because of low disorder prevalence and the lack of a suitable paradigm for testing diets. Here, we screened 35 Drosophila amino acid disorder models for disease-diet interactions and found 26 with diet-altered development and/or survival. Using a targeted multi-nutrient array, we examine the interaction in a model of isolated sulfite oxidase deficiency, an infant-lethal disorder. We show that dietary cysteine depletion normalizes their metabolic profile and rescues development, neurophysiology, behavior, and lifelong fly survival, thus providing a basis for further study into the pathogenic mechanisms involved in this disorder. Our work highlights the diet-sensitive nature of metabolic disorders and establishes Drosophila as a valuable tool for nutrigenomic studies for informing potential dietary therapies.
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Affiliation(s)
- Felipe Martelli
- School of Biological Sciences, Monash University, Clayton, VIC 3800, Australia
| | - Jiayi Lin
- School of Biological Sciences, Monash University, Clayton, VIC 3800, Australia
| | - Sarah Mele
- School of Biological Sciences, Monash University, Clayton, VIC 3800, Australia
| | - Wendy Imlach
- Department of Physiology, Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC 3800, Australia
| | - Oguz Kanca
- Department of Molecular and Human Genetics and Duncan Neurological Research Institute at Texas Children's Hospital, Baylor College of Medicine, Houston, TX, USA
| | - Christopher K Barlow
- Monash Proteomics & Metabolomics Facility, Monash Biomedicine Discovery Institute & Department of Biochemistry and Molecular Biology, Monash University, Clayton, VIC 3800, Australia
| | - Jefferson Paril
- School of BioSciences, The University of Melbourne, Melbourne, VIC 3052, Australia
| | - Ralf B Schittenhelm
- Monash Proteomics & Metabolomics Facility, Monash Biomedicine Discovery Institute & Department of Biochemistry and Molecular Biology, Monash University, Clayton, VIC 3800, Australia
| | - John Christodoulou
- Murdoch Children's Research Institute, Parkville, VIC 3052, Australia; Department of Paediatrics, The University of Melbourne, Melbourne, VIC 3052, Australia
| | - Hugo J Bellen
- Department of Molecular and Human Genetics and Duncan Neurological Research Institute at Texas Children's Hospital, Baylor College of Medicine, Houston, TX, USA
| | - Matthew D W Piper
- School of Biological Sciences, Monash University, Clayton, VIC 3800, Australia.
| | - Travis K Johnson
- School of Biological Sciences, Monash University, Clayton, VIC 3800, Australia; Department of Biochemistry and Chemistry and La Trobe Institute for Molecular Science, La Trobe University, Bundoora, VIC 3086, Australia.
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7
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Latzer IT, Pearl PL. Treatable inherited metabolic epilepsies. Epilepsy Behav 2024; 151:109621. [PMID: 38237465 DOI: 10.1016/j.yebeh.2024.109621] [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: 12/26/2023] [Revised: 12/30/2023] [Accepted: 01/02/2024] [Indexed: 02/09/2024]
Abstract
Inherited metabolic epilepsies (IMEs) represent inherited metabolic disorders predominately presenting with seizures. While most IMEs are currently managed with symptomatic and supportive therapies, some are amenable to disorder-specific targeted treatments. In most cases, these treatments are effective only if given in a narrow time window early in the lives of affected patients. Hence, prompt recognition of treatable inherited metabolic epilepsies at an early age and as soon as symptoms appear has paramount importance. Herein, we provide an overview of inherited metabolic epilepsies, which presently have established targeted treatments showing clinical efficacy in reducing seizure burden and improving neurodevelopmental outcomes. These therapeutic modalities range from specific diets, vitamins, and supplementation of organic compounds to synthetic pharmacological agents and novel genetic-based therapies that alter the biochemical pathways of these disorders at the cellular or molecular level, steering them to their normal function.
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Affiliation(s)
- Itay Tokatly Latzer
- Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA; Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel
| | - Phillip L Pearl
- Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA.
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8
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Nevin SM, McGill BC, Kelada L, Hilton G, Maack M, Elvidge KL, Farrar MA, Baynam G, Katz NT, Donovan L, Grattan S, Signorelli C, Bhattacharya K, Nunn K, Wakefield CE. The psychosocial impact of childhood dementia on children and their parents: a systematic review. Orphanet J Rare Dis 2023; 18:277. [PMID: 37679855 PMCID: PMC10486052 DOI: 10.1186/s13023-023-02859-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Accepted: 08/20/2023] [Indexed: 09/09/2023] Open
Abstract
BACKGROUND Childhood dementias are a group of rare and ultra-rare paediatric conditions clinically characterised by enduring global decline in central nervous system function, associated with a progressive loss of developmentally acquired skills, quality of life and shortened life expectancy. Traditional research, service development and advocacy efforts have been fragmented due to a focus on individual disorders, or groups classified by specific mechanisms or molecular pathogenesis. There are significant knowledge and clinician skill gaps regarding the shared psychosocial impacts of childhood dementia conditions. This systematic review integrates the existing international evidence of the collective psychosocial experiences of parents of children living with dementia. METHODS We used the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. We systematically searched four databases to identify original, peer-reviewed research reporting on the psychosocial impacts of childhood dementia, from the parent perspective. We synthesised the data into three thematic categories: parents' healthcare experiences, psychosocial impacts, and information and support needs. RESULTS Nineteen articles met review criteria, representing 1856 parents. Parents highlighted extensive difficulties connecting with an engaged clinical team and navigating their child's rare, life-limiting, and progressive condition. Psychosocial challenges were manifold and encompassed physical, economic, social, emotional and psychological implications. Access to coordinated healthcare and community-based psychosocial supports was associated with improved parent coping, psychological resilience and reduced psychological isolation. Analysis identified a critical need to prioritize access to integrated family-centred psychosocial supports throughout distinct stages of their child's condition trajectory. CONCLUSION This review will encourage and guide the development of evidence-based and integrated psychosocial resources to optimise quality of life outcomes for of children with dementia and their families.
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Affiliation(s)
- Suzanne M Nevin
- School of Clinical Medicine, UNSW Medicine and Health, Discipline of Paediatrics and Child Health, Sydney, Australia.
- Behavioral Sciences Unit, Kids Cancer Centre, Sydney Children's Hospital, Randwick, Australia.
| | - Brittany C McGill
- School of Clinical Medicine, UNSW Medicine and Health, Discipline of Paediatrics and Child Health, Sydney, Australia
- Behavioral Sciences Unit, Kids Cancer Centre, Sydney Children's Hospital, Randwick, Australia
| | - Lauren Kelada
- School of Clinical Medicine, UNSW Medicine and Health, Discipline of Paediatrics and Child Health, Sydney, Australia
- Behavioral Sciences Unit, Kids Cancer Centre, Sydney Children's Hospital, Randwick, Australia
| | - Gail Hilton
- Childhood Dementia Initiative, Sydney, NSW, Australia
| | - Megan Maack
- Childhood Dementia Initiative, Sydney, NSW, Australia
| | | | - Michelle A Farrar
- School of Clinical Medicine, UNSW Medicine and Health, Discipline of Paediatrics and Child Health, Sydney, Australia
- Department of Neurology, Sydney Children's Hospital, Randwick, Australia
| | - Gareth Baynam
- Faculty of Health and Medical Sciences, Division of Paediatrics, University of Western Australia, Western Australia, Australia
- Rare Care Centre, Perth Children's Hospital, Perth, WA, Australia
- Telethon Kids Institute, Perth, WA, Australia
| | - Naomi T Katz
- Victorian Paediatric Palliative Care Program, Royal Children's Hospital, Melbourne, VIC, Australia
| | - Leigh Donovan
- School of Clinical Medicine, UNSW Medicine and Health, Discipline of Paediatrics and Child Health, Sydney, Australia
- Behavioral Sciences Unit, Kids Cancer Centre, Sydney Children's Hospital, Randwick, Australia
| | - Sarah Grattan
- School of Clinical Medicine, UNSW Medicine and Health, Discipline of Paediatrics and Child Health, Sydney, Australia
| | - Christina Signorelli
- School of Clinical Medicine, UNSW Medicine and Health, Discipline of Paediatrics and Child Health, Sydney, Australia
- Behavioral Sciences Unit, Kids Cancer Centre, Sydney Children's Hospital, Randwick, Australia
| | - Kaustuv Bhattacharya
- Genetic Metabolic Disorders Service, Sydney Children's Hospitals' Network, Randwick and Westmead, Australia
- Faculty of Medicine and Health, Discipline of Genomics, Sydney University, Westmead, Australia
| | - Kenneth Nunn
- Department of Psychological Medicine, Children's Hospital at Westmead, Sydney, NSW, Australia
| | - Claire E Wakefield
- School of Clinical Medicine, UNSW Medicine and Health, Discipline of Paediatrics and Child Health, Sydney, Australia
- Behavioral Sciences Unit, Kids Cancer Centre, Sydney Children's Hospital, Randwick, Australia
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9
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Thewamit R, Khongkhatithum C, Thampratankul L, Kamolvisit W, Khongkrapan A, Wattanasirichaigoon D. Case report: Severe nonketotic hyperglycinemia in a neonate without apparent seizures but concomitant cleft palate and cerebral sinovenous thrombosis. Front Pediatr 2023; 11:1155035. [PMID: 37614902 PMCID: PMC10442541 DOI: 10.3389/fped.2023.1155035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Accepted: 07/20/2023] [Indexed: 08/25/2023] Open
Abstract
Nonketotic hyperglycinemia (NKH) is in most cases a fatal inborn error of metabolism which usually presents during the neonatal period as encephalopathy and refractory seizures. The reported congenital anomalies associated with NKH included corpus callosal agenesis, club foot, cleft palate, and congenital heart disease. Here, we report a newborn who presented with encephalopathy without overt seizures, cerebral venous sinus thrombosis, and cleft palate. Electroencephalography showed a burst suppression pattern, which suggests the etiology could be due to a metabolic or genetic disorder. The amino acid analysis of plasma and cerebrospinal fluid showed elevated glycine. Whole exome sequencing identified a heterozygous c.492C > G; p.Tyr164Ter variant in exon 4 of the GLDC gene inherited from the patient's father. Further long-read whole genome sequencing revealed an exon 1-2 deletion in the GLDC gene inherited from the patient's mother. Additional analyses revealed no pathogenic variants of the cleft palate-related genes. The cleft palate may be an associated congenital anomaly in NKH. Regarding cerebral venous sinus thrombosis, we found a heterozygous variant (p.Arg189Trp) of the PROC gene, which is a common cause of thrombophilia among Thai newborns. A neonate with NKH could present with severe encephalopathy without seizures. A close follow up for clinical changes and further next generation sequencing are crucial for definite diagnosis in neonates with encephalopathy of unclear cause.
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Affiliation(s)
- Rapeepat Thewamit
- Division of Neurology, Department of Pediatrics, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
| | - Chaiyos Khongkhatithum
- Division of Neurology, Department of Pediatrics, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
| | - Lunliya Thampratankul
- Division of Neurology, Department of Pediatrics, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
| | - Wuttichart Kamolvisit
- Division of Medical Genetics and Metabolism, Department of Pediatrics, King Chulalongkorn Memorial Hospital, Bangkok, Thailand
| | - Arthaporn Khongkrapan
- Division of Medical Genetics, Department of Pediatrics, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
| | - Duangrurdee Wattanasirichaigoon
- Division of Medical Genetics, Department of Pediatrics, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
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10
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Jiménez-Fernández S, Gurpegui M, de Leon J, Gutiérrez-Rojas L. Clozapine for the treatment of pediatric encephalopathy associated with nonketotic hyperglycinemia. REVISTA DE PSIQUIATRIA Y SALUD MENTAL 2022; 15:287-289. [PMID: 36513404 DOI: 10.1016/j.rpsmen.2022.10.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Accepted: 06/15/2022] [Indexed: 12/14/2022]
Affiliation(s)
- Sara Jiménez-Fernández
- Child and Adolescent Mental Health Unit, Jaén University Hospital, Jaén, Spain; CTS-549 Research Group (Psychiatry and Neurosciences), Junta de Andalucía, Granada, Spain.
| | - Manuel Gurpegui
- CTS-549 Research Group (Psychiatry and Neurosciences), Junta de Andalucía, Granada, Spain; Granada Center for Psychiatric Studies, Granada, Spain
| | - Jose de Leon
- Mental Health Research Center at Eastern State Hospital, Lexington, KY, USA; Biomedical Research Centre in Mental Health Net (CIBERSAM), Santiago Apóstol Hospital, University of the Basque Country, Vitoria, Spain
| | - Luis Gutiérrez-Rojas
- CTS-549 Research Group (Psychiatry and Neurosciences), Junta de Andalucía, Granada, Spain; Department of Psychiatry, University of Granada, Granada, Spain; Psychiatry Service, San Cecilio University Hospital, Granada, Spain
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11
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Ning JJ, Li F, Li SQ. Clinical and genetic analysis of nonketotic hyperglycinemia: A case report. World J Clin Cases 2022; 10:7982-7988. [PMID: 36158497 PMCID: PMC9372859 DOI: 10.12998/wjcc.v10.i22.7982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Revised: 05/19/2022] [Accepted: 07/06/2022] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Nonketotic hyperglycinemia (NKH) is a rare autosomal recessive genetic disorder of abnormal glycine metabolism caused by insufficient activity of the glycine cleavage enzyme system. Glycine is believed to function mainly as an inhibitory neurotransmitter, but it can also act as a co-agonist of the N-methyl-D-aspartate (NMDA) receptor. The accumulation of a large amount of glycine in the brain leads to neuronal and axonal injury via overactivation of NMDA receptors located in the hippocampus, cerebral cortex, olfactory bulb, and cerebellum and to stimulation of the inhibitory function of glycine receptors located in the spinal cord and brain stem, resulting in central apnea, hiccups, and hypotonia in the early stage of the disease.
CASE SUMMARY The child described in this report had typical clinical manifestations of NKH, such as hiccups, disturbance of consciousness, hypotonia, and convulsions, within the first week after birth. Whole-exome genetic testing revealed that the child had a compound heterozygous mutation, namely, c.395C>A (p.S132X) and c.2182G>A (p.G728R), in the GLDC gene, and he was diagnosed with NKH. For treatment, we administered an oral levetiracetam solution and added topiramate and prednisone for epilepsy control, but the epilepsy remained uncontrollable. Ketogenic diet therapy was started at 6 mo of age, his seizures were significantly reduced, and there were no obvious adverse reactions during ketogenic treatment. Furthermore, we found that with the development of the disease, high levels of serum glycine decreased or even disappeared without intervention, and as the disease progressed, the corpus callosum became dysplastic.
CONCLUSION This case shows that plasma glycine levels cannot be used to evaluate the prognosis of NKH, that the development of the corpus callosum can be affected by NKH, and that a ketogenic diet may be effective for seizure control in NKH patients.
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Affiliation(s)
- Jun-Jie Ning
- Department of Pediatric Intensive Care Unit, First People's Hospital of Zigong City, Zigong 643000, Sichuan Province, China
| | - Feng Li
- Department of Pediatric Intensive Care Unit, First People's Hospital of Zigong City, Zigong 643000, Sichuan Province, China
| | - Sheng-Qiu Li
- Department of Pediatric Intensive Care Unit, First People's Hospital of Zigong City, Zigong 643000, Sichuan Province, China
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12
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Silksmith B, Munot P, Starling L, Pujar S, Matthews E. Accelerating the genetic diagnosis of neurological disorders presenting with episodic apnoea in infancy. THE LANCET. CHILD & ADOLESCENT HEALTH 2022; 6:495-508. [PMID: 35525254 DOI: 10.1016/s2352-4642(22)00091-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Revised: 02/25/2022] [Accepted: 03/03/2022] [Indexed: 11/26/2022]
Abstract
Unexplained episodic apnoea in infants (aged ≤1 year), including recurrent brief (<1 min) resolved unexplained events (known as BRUE), can be a diagnostic challenge. Recurrent unexplained apnoea might suggest a persistent, debilitating, and potentially fatal disorder. Genetic diseases are prevalent among this group, particularly in those who present with paroxysmal or episodic neurological symptoms. These disorders are individually rare and challenging for a general paediatrician to recognise, and there is often a delayed or even posthumous diagnosis (sometimes only made in retrospect when a second sibling becomes unwell). The disorders can be debilitating if untreated but pharmacotherapies are available for the vast majority. That any child should suffer from unnecessary morbidity or die from one of these disorders without a diagnosis or treatment having been offered is a tragedy; therefore, there is an urgent need to simplify and expedite the diagnostic journey. We propose an apnoea gene panel for hospital specialists caring for any infant who has recurrent apnoea without an obvious cause. This approach could remove the need to identify individual rare conditions, speed up diagnosis, and improve access to therapy, with the ultimate aim of reducing morbidity and mortality.
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Affiliation(s)
- Bryony Silksmith
- Department of Neurology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Pinki Munot
- Dubowitz Neuromuscular Centre, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Luke Starling
- Centre for Inherited Cardiovascular Diseases, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Suresh Pujar
- Department of Neurology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Emma Matthews
- Atkinson-Morley Neuromuscular Centre, Department of Neurology, St George's University Hospitals NHS Foundation Trust, London, UK; Molecular and Clinical Sciences Research Institute, St George's University of London, London, UK.
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13
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Clozapine for the treatment of pediatric encephalopathy associated with nonketotic hyperglycinemia. REVISTA DE PSIQUIATRÍA Y SALUD MENTAL 2022. [DOI: 10.1016/j.rpsm.2022.06.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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14
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Nonketotic Hyperglycinemia: Insight into Current Therapies. J Clin Med 2022; 11:jcm11113027. [PMID: 35683414 PMCID: PMC9181064 DOI: 10.3390/jcm11113027] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2022] [Revised: 05/19/2022] [Accepted: 05/24/2022] [Indexed: 12/10/2022] Open
Abstract
Nonketotic hyperglycinemia (NKH) is a rare inborn error of glycine metabolism that is characterized by the accumulation of glycine in all tissues, especially in the central nervous system (CNS). Based on clinical outcomes, NKH can be divided into two forms, i.e., severe and attenuated NKH. A poor prognosis, including no developmental progress and intractable epilepsy, is typical of severe NKH, whereas patients with the attenuated form present with varied symptoms and neurodevelopmental outcomes. So far, no causal treatment of NKH is known. Currently, the therapy is based on sodium benzoate and NMDA (The N-methyl-D-aspartate receptor) receptor site antagonists (dextromethorphan, ketamine). Different clinical outcomes of the therapy raise doubts about the effectiveness of the treatment. The purpose of this review is to summarize the therapeutic potential, challenges and effectiveness of different NKH therapies.
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15
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Kuseyri Hübschmann O, Palacios NAJ, Olivella M, Guder P, Zafeiriou DI, Horvath G, Kulhánek J, Pearson TS, Kuster A, Cortès-Saladelafont E, Ibáñez S, García-Jiménez MC, Honzík T, Santer R, Jeltsch K, Garbade SF, Hoffmann GF, Opladen T, García-Cazorla Á. An integrative approach to predict severity in nonketotic hyperglycinemia. Ann Neurol 2022; 92:292-303. [PMID: 35616651 DOI: 10.1002/ana.26423] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Revised: 05/19/2022] [Accepted: 05/23/2022] [Indexed: 11/11/2022]
Abstract
OBJECTIVE Glycine encephalopathy, also known as nonketotic hyperglycinemia (NKH), is an inherited neurometabolic disorder with variable clinical course and severity, ranging from infantile epileptic encephalopathy to psychiatric disorders. A precise phenotypic characterization and an evaluation of predictive approaches are needed. METHODS Longitudinal clinical and biochemical data of 25 individuals with NKH from the patient registry of International Working Group on Neurotransmitter related Disorders were studied with in silico analyses, pathogenicity scores and molecular modeling of GLDC and AMT variants. RESULTS Symptom onset (p<0· 01) and diagnosis occur earlier in life in severe NKH (p<0· 01). Presenting symptoms affect the age at diagnosis. Psychiatric problems occur predominantly in attenuated NKH. Onset-age ≥3 months (66% specificity, 100% sensitivity, AUC = 0·87) and cerebrospinal fluid (CSF)/plasma glycine ratio ≤0· 09 (57% specificity, 100% sensitivity, AUC = 0·88) are sensitive indicators for attenuated NKH while CSF glycine concentration ≥116· 5 μmol/L (100% specificity, 93% sensitivity, AUC = 0·97) and CSF/plasma glycine ratio ≥0· 15 (100% specificity, 64% sensitivity, AUC = 0·88) are specific for severe forms. A ratio threshold of 0· 128 discriminates the overlapping range. We present ten new GLDC variants. Two mild variants resulted in attenuated, while two severe variants or one mild and one severe variant lead to severe phenotype. Based on clinical, biochemical and genetic parameter we propose a severity prediction model. INTERPRETATION This study widens the phenotypic spectrum of attenuated NKH and expands the number of pathogenic variants. The multiparametric approach provides a promising tool to predict disease severity, helping to improve clinical management strategies. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Oya Kuseyri Hübschmann
- University Children's Hospital Heidelberg, Division of Child Neurology and Metabolic Disorders, Heidelberg, Germany
| | - Natalia Alexandra Julia Palacios
- Inborn errors of metabolism Unit, Department of Neurology, Institut de Recerca Sant Joan de Déu, CIBERER-ISCIII and MetabERN, Barcelona, Spain
| | - Mireia Olivella
- Bioinformatics and Medical Statistics Group. Facultat de Ciències i Tecnologia. Universitat de Vic - Universitat Central de Catalunya (UVic-UCC), Vic, Barcelona, Spain
| | - Philipp Guder
- Children's Hospital, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Dimitrios I Zafeiriou
- First Department of Pediatrics Aristotle University of Thessaloniki Egnatia St. 106 54622, Thessaloniki, Greece
| | - Gabriella Horvath
- University of British Columbia, Department of Pediatrics, Division of Biochemical Genetics, BC Children's Hospital, Vancouver, BC, Canada
| | - Jan Kulhánek
- Department of Pediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague, Czech Republic
| | - Toni S Pearson
- Department of Neurology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Alice Kuster
- Department of Neurometabolism and Metabolic Disorders, University Hospital of Nantes, Nantes, France
| | - Elisenda Cortès-Saladelafont
- Inborn errors of metabolism Unit, Department of Neurology, Institut de Recerca Sant Joan de Déu, CIBERER-ISCIII and MetabERN, Barcelona, Spain.,Inborn Errors of Metabolism and Child Neurology Unit, Department of Pediatrics, Hospital Germans Trias i Pujol, Badalona and Faculty of Medicine, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Salvador Ibáñez
- Department of Pediatric Neurology, Hospital Virgen de la Arrixaca, Murcia, Spain
| | | | - Tomáš Honzík
- Department of Pediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague, Czech Republic
| | - René Santer
- Children's Hospital, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Kathrin Jeltsch
- University Children's Hospital Heidelberg, Division of Child Neurology and Metabolic Disorders, Heidelberg, Germany
| | - Sven F Garbade
- University Children's Hospital Heidelberg, Dietmar-Hopp Metabolic Center, Heidelberg, Germany
| | - Georg F Hoffmann
- University Children's Hospital Heidelberg, Division of Child Neurology and Metabolic Disorders, Heidelberg, Germany
| | - Thomas Opladen
- University Children's Hospital Heidelberg, Division of Child Neurology and Metabolic Disorders, Heidelberg, Germany
| | - Ángeles García-Cazorla
- Inborn errors of metabolism Unit, Department of Neurology, Institut de Recerca Sant Joan de Déu, CIBERER-ISCIII and MetabERN, Barcelona, Spain
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16
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Bayrak H, Yıldız Y, Olgaç A, Kasapkara ÇS, Küçükcongar A, Zenciroğlu A, Yüksel D, Ceylaner S, Kılıç M. Genotypic and phenotypic features in Turkish patients with classic nonketotic hyperglycinemia. Metab Brain Dis 2021; 36:1213-1222. [PMID: 33791923 DOI: 10.1007/s11011-021-00718-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Accepted: 03/14/2021] [Indexed: 10/21/2022]
Abstract
Nonketotic hyperglycinemia is an autosomal recessive inborn error of glycine metabolism, characterized by deficient activity of the glycine cleavage enzyme system. Classic nonketotic hyperglycinemia is caused by mutations or genomic changes in genes that encode the protein components of the glycine cleavage enzyme system. We aimed to investigate clinical, biochemical, radiological findings and molecular genetic data in ten Turkish patients with classic nonketotic hyperglycinemia. Ten Turkish patients who were diagnosed with classic nonketotic hyperglycinemia in a single center from 2013 to 2019 were included in this study. Their clinical, radiological, electrophysiological and laboratory data were collected retrospectively. Sixty percent of the patients were in neonatal group, while 40 % of the patients were infantile. There were no late-onset patients. 90 % of the patients had the severe form. All patients had developmental delay and seizures. Mortality ratio was 30 % in all groups and 50 % in the neonatal group, while no mortality was seen in infantile group. Median (range) values of cerebrospinal fluid (CSF) glycine levels, plasma glycine levels and CSF/plasma glycine ratios were 148 (15-320) µmol/L, 896 (87-1910) µmol/L, 0.17 (0.09-0.21) respectively. Diffuse hypomyelination and corpus callosum anomaly were the most common cranial MRI findings and multifocal epileptic activity and burst supression pattern were the most common electroencephalographic findings. Six patients had variants in GLDC gene and four in AMT gene; five novel variants including AMT gene deletion were detected. Prognosis was poor and treatment was not effective, especially in the severe form. Classic nonketotic hyperglycinemia causes high morbidity and mortality. Neonatal-onset disease was more common and severe than infantile-onset disease. The ratio of AMT gene variants might be higher in Turkey than other countries. AMT gene deletion also plays a role in the etiology of classic nonketotic hyperglycinemia.
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Affiliation(s)
- Harun Bayrak
- Department of Pediatrics, Sami Ulus Children Hospital, Ankara, Turkey
| | - Yılmaz Yıldız
- Metabolism Unit, Sami Ulus Children Hospital, Babur cad. No: 44, Altındağ, Ankara, 06080, Turkey
| | - Asburçe Olgaç
- Metabolism Unit, Sami Ulus Children Hospital, Babur cad. No: 44, Altındağ, Ankara, 06080, Turkey
| | - Çiğdem Seher Kasapkara
- Metabolism Unit, Sami Ulus Children Hospital, Babur cad. No: 44, Altındağ, Ankara, 06080, Turkey
| | | | | | - Deniz Yüksel
- Neurology Unit, Sami Ulus Children Hospital, Ankara, Turkey
| | - Serdar Ceylaner
- Intergen, Genetic and Rare Disease Diagnosis and Research Center, Genetic Laboratory, Ankara, Turkey
| | - Mustafa Kılıç
- Metabolism Unit, Sami Ulus Children Hospital, Babur cad. No: 44, Altındağ, Ankara, 06080, Turkey.
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17
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Stroebel D, Mony L, Paoletti P. Glycine agonism in ionotropic glutamate receptors. Neuropharmacology 2021; 193:108631. [PMID: 34058193 DOI: 10.1016/j.neuropharm.2021.108631] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Revised: 05/21/2021] [Accepted: 05/23/2021] [Indexed: 12/12/2022]
Abstract
Ionotropic glutamate receptors (iGluRs) are ligand-gated ion channels that mediate the majority of excitatory neurotransmission in the vertebrate CNS. Classified as AMPA, kainate, delta and NMDA receptors, iGluRs are central drivers of synaptic plasticity widely considered as a major cellular substrate of learning and memory. Surprisingly however, five out of the eighteen vertebrate iGluR subunits do not bind glutamate but glycine, a neurotransmitter known to mediate inhibitory neurotransmission through its action on pentameric glycine receptors (GlyRs). This is the case of GluN1, GluN3A, GluN3B, GluD1 and GluD2 subunits, all also binding the D amino acid d-serine endogenously present in many brain regions. Glycine and d-serine action and affinities broadly differ between glycinergic iGluR subtypes. On 'conventional' GluN1/GluN2 NMDA receptors, glycine (or d-serine) acts in concert with glutamate as a mandatory co-agonist to set the level of receptor activity. It also regulates the receptor's trafficking and expression independently of glutamate. On 'unconventional' GluN1/GluN3 NMDARs, glycine acts as the sole agonist directly triggering opening of excitatory glycinergic channels recently shown to be physiologically relevant. On GluD receptors, d-serine on its own mediates non-ionotropic signaling involved in excitatory and inhibitory synaptogenesis, further reinforcing the concept of glutamate-insensitive iGluRs. Here we present an overview of our current knowledge on glycine and d-serine agonism in iGluRs emphasizing aspects related to molecular mechanisms, cellular function and pharmacological profile. The growing appreciation of the critical influence of glycine and d-serine on iGluR biology reshapes our understanding of iGluR signaling diversity and complexity, with important implications in neuropharmacology.
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Affiliation(s)
- David Stroebel
- Institut de Biologie de l'Ecole Normale Supérieure (IBENS), Ecole Normale Supérieure, Université PSL, CNRS, INSERM, F-75005, Paris, France.
| | - Laetitia Mony
- Institut de Biologie de l'Ecole Normale Supérieure (IBENS), Ecole Normale Supérieure, Université PSL, CNRS, INSERM, F-75005, Paris, France
| | - Pierre Paoletti
- Institut de Biologie de l'Ecole Normale Supérieure (IBENS), Ecole Normale Supérieure, Université PSL, CNRS, INSERM, F-75005, Paris, France.
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18
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Leung KY, De Castro SCP, Galea GL, Copp AJ, Greene NDE. Glycine Cleavage System H Protein Is Essential for Embryonic Viability, Implying Additional Function Beyond the Glycine Cleavage System. Front Genet 2021; 12:625120. [PMID: 33569080 PMCID: PMC7868403 DOI: 10.3389/fgene.2021.625120] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Accepted: 01/04/2021] [Indexed: 12/03/2022] Open
Abstract
Glycine cleavage system H protein (GCSH) is a component of the glycine cleavage system (GCS), a conserved protein complex that acts to decarboxylate glycine. Mutation of AMT or GLDC, encoding the GCS components aminomethyltransferase and glycine decarboxylase, can cause malformations of the developing CNS (neural tube defects (NTDs) and ventriculomegaly) as well as a post-natal life-limiting neurometabolic disorder, Non-Ketotic Hyperglycinemia. In contrast, it is unclear whether mutation of GCSH contributes to these conditions and we therefore investigated GCSH loss of function in mice. Mice that were heterozygous for a Gcsh null allele were viable and did not exhibit elevated plasma glycine. Moreover, heterozygous mutation of Gcsh did not increase the frequency of NTDs in Gldc mutant embryos. Homozygous Gcsh null mice were not recovered at post-natal stages. Analysis of litters at E8.5-10.5, revealed the presence of homozygous null embryos which were much smaller than littermates and had failed to develop beyond early post-implantation stages with no visible somites or head-folds. Hence, unlike null mutations of Gldc or Amt, which are compatible with embryonic survival despite the presence of NTDs, loss of Gcsh causes embryonic death prior to mid-gestation. Maternal supplementation with formate did not restore embryonic development beyond E7.5, suggesting that the primary cause of lethality was not loss of glycine cleavage activity or suppression of folate one-carbon metabolism. These findings suggest that GCSH has additional roles beyond function in the glycine cleavage system. We hypothesize that GCSH potentially acts in lipoylation of 2-oxoacid dehydrogenase proteins, as reported in bacteria.
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Affiliation(s)
- Kit-Yi Leung
- Great Ormond Street Institute of Child Health, University College London, London, United Kingdom
| | - Sandra C P De Castro
- Great Ormond Street Institute of Child Health, University College London, London, United Kingdom
| | - Gabriel L Galea
- Great Ormond Street Institute of Child Health, University College London, London, United Kingdom
| | - Andrew J Copp
- Great Ormond Street Institute of Child Health, University College London, London, United Kingdom
| | - Nicholas D E Greene
- Great Ormond Street Institute of Child Health, University College London, London, United Kingdom
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19
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Santos C, Pai YJ, Mahmood MR, Leung KY, Savery D, Waddington SN, Copp AJ, Greene NDE. Impaired folate 1-carbon metabolism causes formate-preventable hydrocephalus in glycine decarboxylase-deficient mice. J Clin Invest 2020; 130:1446-1452. [PMID: 31794432 PMCID: PMC7269562 DOI: 10.1172/jci132360] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Accepted: 11/20/2019] [Indexed: 12/16/2022] Open
Abstract
Ventriculomegaly and hydrocephalus are associated with loss of function of glycine decarboxylase (Gldc) in mice and in humans suffering from non-ketotic hyperglycinemia (NKH), a neurometabolic disorder characterized by accumulation of excess glycine. Here, we showed that ventriculomegaly in Gldc-deficient mice is preceded by stenosis of the Sylvian aqueduct and malformation or absence of the subcommissural organ and pineal gland. Gldc functions in the glycine cleavage system, a mitochondrial component of folate metabolism, whose malfunction results in accumulation of glycine and diminished supply of glycine-derived 1-carbon units to the folate cycle. We showed that inadequate 1-carbon supply, as opposed to excess glycine, is the cause of hydrocephalus associated with loss of function of the glycine cleavage system. Maternal supplementation with formate prevented both ventriculomegaly, as assessed at prenatal stages, and postnatal development of hydrocephalus in Gldc-deficient mice. Furthermore, ventriculomegaly was rescued by genetic ablation of 5,10-methylene tetrahydrofolate reductase (Mthfr), which results in retention of 1-carbon groups in the folate cycle at the expense of transfer to the methylation cycle. In conclusion, a defect in folate metabolism can lead to prenatal aqueduct stenosis and resultant hydrocephalus. These defects are preventable by maternal supplementation with formate, which acts as a 1-carbon donor.
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Affiliation(s)
- Chloe Santos
- UCL Great Ormond Street Institute of Child Health and
| | - Yun Jin Pai
- UCL Great Ormond Street Institute of Child Health and
| | | | - Kit-Yi Leung
- UCL Great Ormond Street Institute of Child Health and
| | - Dawn Savery
- UCL Great Ormond Street Institute of Child Health and
| | - Simon N Waddington
- EGA Institute for Women's Health, University College London, London, United Kingdom.,MRC Antiviral Gene Therapy Research Unit, Faculty of Health Science, University of the Witswatersrand, Johannesburg, South Africa
| | - Andrew J Copp
- UCL Great Ormond Street Institute of Child Health and
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20
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Eto F, Sato S, Setou M, Yao I, Sato K. Mass spectrometry imaging reveals glycine distribution in the developing and adult mouse brain. J Chem Neuroanat 2020; 110:101869. [PMID: 33098935 DOI: 10.1016/j.jchemneu.2020.101869] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Revised: 09/30/2020] [Accepted: 10/01/2020] [Indexed: 10/23/2022]
Abstract
Glycine is an important amino acid in the central nervous system. The aberrant conditions of glycine concentrations cause sever neurological disorders, such as nonketotic-hyperglycinemia (NKH), also known as glycine encephalopathy. Therefore, a better understanding of its relative abundance and distribution in the developing and adult brains would provide insights into the pathogeneses of this kind of disorders. Matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) imaging has been used for direct molecular-specific compound detection, distribution mapping, and identifying molecular species in tissue sections. Although a few reports have already shown the imaging of glycine using MALDI-MS in the adult mouse brain, they lack detailed neuroanatomical and developmental evaluations. We, thus, investigated the detailed distribution and abundance of glycine not only in the adult mouse brain but also in the developing mouse brain using this technique. In both brains, we detected derivatized glycine throughout the mouse brain. Interestingly, in both brains, derivatized glycine was abundantly detected in the brain stem. The other areas showed relatively lower signal intensities. As many model mice are used for glycine-related diseases, MALDI-MS is a suitable technique to analyze the pathogenesis of these diseases.
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Affiliation(s)
- Fumihiro Eto
- Department of Optical Imaging, Institute for Medical Photonics Research, Preeminent Medical Photonics Education & Research Center, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, Shizuoka, 431-3192, Japan; Department of Cellular and Molecular Anatomy, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, Shizuoka, 431-3192, Japan
| | - Shumpei Sato
- Department of Cellular and Molecular Anatomy, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, Shizuoka, 431-3192, Japan; International Mass Imaging Center, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, Shizuoka, 431-3192, Japan
| | - Mitsutoshi Setou
- Department of Cellular and Molecular Anatomy, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, Shizuoka, 431-3192, Japan; International Mass Imaging Center, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, Shizuoka, 431-3192, Japan; Department of Systems Molecular Anatomy, Institute for Medical Photonics Research, Preeminent Medical Photonics Education & Research Center, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, Shizuoka, 431-3192, Japan
| | - Ikuko Yao
- Department of Optical Imaging, Institute for Medical Photonics Research, Preeminent Medical Photonics Education & Research Center, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, Shizuoka, 431-3192, Japan; International Mass Imaging Center, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, Shizuoka, 431-3192, Japan
| | - Kohji Sato
- Department of Organ & Tissue Anatomy, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, Shizuoka, 431-3192, Japan.
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21
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Ichikawa K, Inami Y, Kaneko K. Seventeen-year long-term survival of a case of neonatal nonketotic hyperglycinemia. Pediatr Int 2020; 62:1111-1113. [PMID: 32754929 DOI: 10.1111/ped.14254] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/05/2020] [Revised: 04/01/2020] [Accepted: 04/15/2020] [Indexed: 11/29/2022]
Affiliation(s)
- Kazushi Ichikawa
- Department of Pediatrics, Fujisawa City Hospital, Kanagawa, Japan
| | - Yuki Inami
- Department of Pediatrics, Fujisawa City Hospital, Kanagawa, Japan
| | - Kaori Kaneko
- Department of Pediatrics, Fujisawa City Hospital, Kanagawa, Japan
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22
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Bin Arif T, Ahmed J, Malik F, Nasir S, Khan TM. Neonatal Nonketotic Hyperglycinemia: A Rare Case from Pakistan. Cureus 2020; 12:e7235. [PMID: 32280576 PMCID: PMC7145377 DOI: 10.7759/cureus.7235] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Accepted: 03/10/2020] [Indexed: 12/22/2022] Open
Abstract
Nonketotic hyperglycinemia (NKH) is an autosomal recessive disorder caused by a defect in glycine cleavage enzyme. It leads to the accumulation of glycine in the body tissues, blood, and cerebrospinal fluid (CSF). Most NKH cases are diagnosed during the natal period of life and are fatal if not promptly diagnosed and managed. Here we present a case of a two-day-old child who presented with reluctant feeding and lethargy. She had reduced tone in all four limbs and a Glasgow Coma Scale score of 9. Keeping an infectious etiology in mind, she was started on cefotaxime and amikacin. The patient was shifted to the neonatal intensive care unit; however, no improvement in the patient's condition was seen and antibiotics were changed to linezolid and meropenem along with initiation of acyclovir. The patient's blood and CSF cultures were negative. Serum amino acid chromatography showed elevated levels of glycine, and a diagnosis of NKH was made. The patient was managed symptomatically but expired on the 22nd day of admission. The case highlights the importance of prompt diagnosis and management of aminoacidopathies. Nearly all metabolic disorders have similar clinical presentations, and an early diagnosis can improve the outcome in patients.
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Affiliation(s)
- Taha Bin Arif
- Internal Medicine, Dow University of Health Sciences, Karachi, PAK
| | - Jawad Ahmed
- Internal Medicine, Dow University of Health Sciences, Karachi, PAK
| | - Farheen Malik
- Internal Medicine, Dow University of Health Sciences, Karachi, PAK
| | - Sharmeen Nasir
- Pediatrics, Dow University of Health Sciences, Karachi, PAK
| | - Taj M Khan
- Pediatrics, Baylor College of Medicine/Texas Children's Hospital, Houston, USA
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Tatarinova TV, Deiss T, Franckle L, Beaven S, Davis J. The Impact of MNRI Therapy on the Levels of Neurotransmitters Associated with Inflammatory Processes. Int J Mol Sci 2020; 21:E1358. [PMID: 32085403 PMCID: PMC7072967 DOI: 10.3390/ijms21041358] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2019] [Revised: 02/13/2020] [Accepted: 02/14/2020] [Indexed: 01/02/2023] Open
Abstract
The neurotransmitter levels of representatives from five different diagnosis groups were tested before and after participation in the MNRI®-Masgutova Neurosensorimotor Reflex Intervention. The purpose of this study was to ascertain neurological impact on (1) Developmental disorders, (2) Anxiety disorders/OCD (Obsessive Compulsive Disorder), PTSD (Post-Traumatic Stress disorder), (3) Palsy/Seizure disorders, (4) ADD/ADHD (Attention Deficit Disorder/Attention Deficit Disorder Hyperactive Disorder), and (5) ASD (Autism Spectrum Disorder) disorders. Each participant had a form of neurological dysregulation and typical symptoms respective to their diagnosis. These diagnoses have a severe negative impact on the quality of life, immunity, stress coping, cognitive skills, and social assimilation. This study showed a trend towards optimization and normalization of neurological and immunological functioning, thus supporting the claim that the MNRI method is an effective non-pharmacological neuromodulation treatment of neurological disorders. The effects of MNRI on inflammation have not yet been assessed. The resulting post-MNRI changes in participants' neurotransmitters show significant adjustments in the regulation of the neurotransmitter resulting in being calmer, a decrease of hypervigilance, an increase in stress resilience, behavioral and emotional regulation improvements, a more positive emotional state, and greater control of cognitive processes. In this paper, we demonstrate that the MNRI approach is an intervention that reduces inflammation. It is also likely to reduce oxidative stress and encourage homeostasis of excitatory neurotransmitters. MNRI may facilitate neurodevelopment, build stress resiliency, neuroplasticity, and optimal learning opportunity. There have been no reported side effects of MNRI treatments.
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Affiliation(s)
- Tatiana V. Tatarinova
- Department of Biology, University of La Verne, La Verne, CA 91750, USA
- Functional Genomics Group, Vavilov Institute for General Genetics, Moscow 119991, Russia
- Forest Genomics Laboratory, Siberian Federal University, Krasnoyarsk 660041, Russia
- Bioinformatics Center, Information Transmission Problems Institute, Moscow 127051, Russia
| | - Trina Deiss
- Research Department, United1Front Foundation, Minneapolis, MN 55111, USA;
| | - Lorri Franckle
- Laser Health Department, Laser Health, Orlando, FL 33709, USA;
| | - Susan Beaven
- Family Medicine, St. Petersburg Free Clinic, St. Petersburg, FL 33701, USA;
| | - Jeffrey Davis
- Family Medicine, Prairie Health and Wellness, Wichita, KS 67206, USA;
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24
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Why is folate effective in preventing neural tube closure defects? Med Hypotheses 2019; 134:109429. [PMID: 31634773 DOI: 10.1016/j.mehy.2019.109429] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Revised: 10/03/2019] [Accepted: 10/10/2019] [Indexed: 11/20/2022]
Abstract
Neural tube defects (NTDs) originate from a failure of the embryonic neural tube to close. The pathogenesis of NTDs is largely unknown. Fortunately, adequate maternal folate application is known to reduce the risk of human NTDs. However, why folate reduces NTDs is largely unknown. The main cause for NTDs is the disturbance of the cell growth in the neuroepithelium. Of course, rapid cell growth needs enough synthesis of nuclei acids. Interestingly, folate is used as a source for the synthesis of nucleic acids. Furthermore, glycine cleavage system (GCS) is essential for the synthesis of nucleic acids from folate, and very strongly expressed in neuroepithelial cells, suggesting that these highly proliferating cells need enough synthesis of nuclei acids and high amounts of folate. Taken together, I speculate the following hypothesis; (1) The closure of the neural tube requires rapid growth of neuroepithelial cells. (2) High rates of nuclei acids synthesis are needed for the rapid growth. (3) GCS, which is requisite in nucleic acid synthesis from folate, is expressed very strongly and functions robustly in neuroepithelial cells. (4) Pregnant women require 5-10-fold higher amounts of folate compared to non-pregnant women. (5) So, folate-deficient situations are easy to occur in neuroepithelial cells, resulting in NTDs. (6) Thus, folate is effective to prevent NTDs.
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25
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BoAli AY, Alfadhel M, Tabarki B. Neurometabolic disorders and congenital malformations of the central nervous system. ACTA ACUST UNITED AC 2019; 23:97-103. [PMID: 29664449 PMCID: PMC8015440 DOI: 10.17712/nsj.2018.2.20170481] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Both malformations of the central nervous system and neurometabolic disorders are common, mainly in highly consanguineous populations. Both metabolic pathways and developmental pathways are closely related and interact with each other. Neurometabolic disorders can lead to disturbances in brain development through multiple mechanisms that include deficits in energy metabolism, critical nutrient deficiency, accumulation of neurotoxic substrates, abnormality in cell membrane constituents, and interference in cell-to-cell signaling pathways. The anomalies observed include absent or hypoplastic corpus callosum, midline brain defects, and malformations of the cortex, the cerebellum and the brain stem. Early diagnosis of an underlying inherited neurometabolic disorders is critical for the institution of treatment, which may positively influence prognosis, and allow for proper genetic counseling. In this review, we discuss those disorders in which the structural brain malformation is a dominant feature, and propose a practical approach that will permit a physician to investigate, and treat these disorders.
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Affiliation(s)
- Ahmed Y BoAli
- Divisions of Pediatric Neurology, Department of Pediatrics, Prince Sultan Military Medical City,Riyadh, Kingdom of Saudi Arabia
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Magwebu ZE, Mazinu M, Abdul-Rasool S, Chauke CG. The effect of hyperglycinemic treatment in captive-bred Vervet monkeys (Chlorocebus aethiops). Metab Brain Dis 2019; 34:1467-1472. [PMID: 31230217 DOI: 10.1007/s11011-019-00449-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Accepted: 06/10/2019] [Indexed: 12/24/2022]
Abstract
Nonketotic hyperglycinemia (NKH) is a neuro-metabolic disorder caused by a deficiency in the glycine cleavage system (GCS) and glycine transporter 1 (GlyT1). A case of atypical late onset of NKH has been reported in a colony of captive-bred Vervet monkeys. The purpose of this study was to evaluate the effect of sodium benzoate and dextromethorphan in reducing glycine levels in hyperglycinemic monkeys. Twelve captive-bred Vervet monkeys were assigned into three groups consisting of four animals (control, valproate induced and cataract with spontaneous hyperglycinemia). Valproate was used to elevate glycine levels and the induced group was then treated with sodium benzoate and dextromethorphan together with group three to normalise glycine levels in cerebrospinal fluid (CSF) and plasma. Valproate induction elicited changes in phosphate, alkaline phosphatase and platelet count, however, no significant changes in the glycine levels were observed, and this might be due to the individual variability within the group. The treatment intervention was only obtained in the spontaneous group whereby the glycine levels were normalised in CSF and plasma. Therefore, it can be concluded that sodium benzoate and dextromethorphan treatment was effective and beneficial to the hyperglycinemic group.
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Affiliation(s)
- Zandisiwe E Magwebu
- Primate Unit and Delft Animal Centre, South African Medical Research Council, P.O Box 19070, Tygerberg, Cape Town, 7505, South Africa.
| | - Mikateko Mazinu
- Primate Unit and Delft Animal Centre, South African Medical Research Council, P.O Box 19070, Tygerberg, Cape Town, 7505, South Africa
| | - Sahar Abdul-Rasool
- Medical Bioscience Department, University of the Western Cape, Belville, South Africa
| | - Chesa G Chauke
- Primate Unit and Delft Animal Centre, South African Medical Research Council, P.O Box 19070, Tygerberg, Cape Town, 7505, South Africa
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Poothrikovil RP, Al Thihli K, Al Futaisi A, Al Murshidi F. Nonketotic Hyperglycinemia: Two Case Reports and Review. Neurodiagn J 2019; 59:142-151. [PMID: 31433733 DOI: 10.1080/21646821.2019.1645549] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Nonketotic hyperglycinemia (NKH) or glycine encephalopathy is an autosomal recessive disorder of glycine metabolism resulting in an excessive accumulation of glycine in all body tissues, including the central nervous system. It is caused by a biochemical defect in the glycine cleavage system and considered as a rare disorder with an estimated prevalence of 1:60,000. The neonatal form presents in the first few days of life with progressive encephalopathy, hypotonia, myoclonic jerks, hiccups, seizures, rapid progression to coma and often death due to central apnea. Surviving infants often have severe developmental delay and refractory seizures. Atypical forms of NKH present with heterogeneous and nonspecific disease course. Classical glycine encephalopathy usually carries a very poor prognosis. We describe two neonates who presented with neonatal encephalopathy, apnea, and progressive lethargy. Increased CSF glycine level along with an elevated CSF to plasma glycine ratio was suggestive of classic NKH. Burst suppression EEG and agenesis of the corpus callosum were supportive findings. Evolution of the EEG patterns and course of the disease are discussed in detail. Transient phases of clinical stabilization and normalized plasma biochemical results may not necessarily reflect the actual encephalopathic process. Serial EEGs are helpful to assess the efficacy of treatment and to modify the therapeutic approach.
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Affiliation(s)
- Rajesh P Poothrikovil
- Department of Clinical PhysiologySultan Qaboos University Hospital , Muscat , Sultanate of Oman
| | - Khalid Al Thihli
- Department of Clinical GeneticsSultan Qaboos University Hospital , Muscat , Sultanate of Oman
| | - Amna Al Futaisi
- Department of Child HealthSultan Qaboos University Hospital , Muscat , Sultanate of Oman
| | - Fathiya Al Murshidi
- Department of Clinical GeneticsSultan Qaboos University Hospital , Muscat , Sultanate of Oman
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Kose E, Yis U, Hiz S, Arslan N. A novel mutation in the glycine decarboxylase gene in patient with non-ketotic hyperglycinemia. ACTA ACUST UNITED AC 2019; 22:131-133. [PMID: 28416785 PMCID: PMC5726819 DOI: 10.17712/nsj.2017.2.20160468] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Non-ketotic hyperglycinemia (NKH) is a rare inborn error of metabolism and is caused by a glycine cleavage system deficiency. Eighty-five percent of patients present with the neonatal type of NKH, the infants initially develop lethargy, seizures, and episodes of apnea, and most often death. Between 60-90% of cases are caused by mutations in the glycine decarboxylase (GLDC). We believed that more mutation reports especially for rare disease as NKH help to evaluate the genotype-phenotype relationship in patients with GLDC. In this study, we describe a case of a neonate admitted to intensive care unit with hypotonia, respiratory failure, lethargy, poor feeding. Due to the history of 2 non-ketotic hyperglycinemia diagnosed male siblings, molecular prenatal diagnosis in patient was performed and a novel c.2963G>A (Arg998Gln) homozygous mutation within the GLDC gene has been detected. We aimed to contribute to mutation knowledge pool of GLDC gene with a novel mutation.
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Affiliation(s)
| | | | | | - Nur Arslan
- Division of Pediatric Metabolism and Nutrition, Department of Pediatrics, Faculty of Medicine, Dokuz Eylul University, Izmir, Turkey
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29
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Sato K. Why is glycine cleavage system segmentally expressed in radial glia? J Theor Biol 2019; 470:17-19. [PMID: 30858066 DOI: 10.1016/j.jtbi.2019.03.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Revised: 01/11/2019] [Accepted: 03/08/2019] [Indexed: 11/26/2022]
Affiliation(s)
- Kohji Sato
- Department of Organ & Tissue Anatomy, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashiku, Hamamatsu, Shizuoka 431-3192, Japan.
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30
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Stence NV, Fenton LZ, Levek C, Tong S, Coughlin CR, Hennermann JB, Wortmann SB, Van Hove JLK. Brain imaging in classic nonketotic hyperglycinemia: Quantitative analysis and relation to phenotype. J Inherit Metab Dis 2019; 42:438-450. [PMID: 30737808 DOI: 10.1002/jimd.12072] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Accepted: 02/05/2019] [Indexed: 12/22/2022]
Abstract
Patients with severe nonketotic hyperglycinemia (NKH) have absent psychomotor development and intractable epilepsy, whereas attenuated patients have variable psychomotor development and absent or treatable epilepsy; differences in brain magnetic resonance imaging (MRI) between phenotypes have not been reported. In a retrospective cross-sectional study, we reviewed 38 MRI studies from 24 molecularly proven NKH patients, and 2 transient NKH patients. Quantitative analyses included corpus callosum size, apparent diffusion coefficient, automated brain volumetric analysis, and glycine/creatine ratio by spectroscopy. All patients age <3 months had restricted diffusion in the posterior limb of the internal capsule, anterior brainstem, posterior tegmental tracts, and cerebellum, not present in transient NKH. In older infants, the pattern evolved and included generalized diffusion restriction in the supratentorial white matter, which quantitatively peaked between 3 and 12 months. No patient had absent corpus callosum or gyral malformation. The corpus callosum was relatively short in severe compared to attenuated phenotypes, and thin in severe cases only. The corpus callosum growth rate differed by severity; age-matched Z-scores of thickness worsened in severe cases only. Cerebral volume was decreased in the hippocampus, globus pallidus, cerebral cortex, thalamus, and cerebellum. Severe patients had greatest glycine/creatine ratios. In this study, no brain malformations were identified. The growth failure of the corpus callosum is worse in severe NKH, whereas the diffusion restriction pattern, reflecting microspongiosis, does not discriminate by phenotypic severity. NKH is therefore a disorder of brain growth best recognized in the corpus callosum, whereas spongiosis is not prognostic.
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Affiliation(s)
- Nicholas V Stence
- Department of Radiology, University of Colorado and Children's Hospital Colorado, Aurora, Colorado
| | - Laura Z Fenton
- Department of Radiology, University of Colorado and Children's Hospital Colorado, Aurora, Colorado
| | - Claire Levek
- Department of Pediatrics, Research Institute Biostatistics Core, University of Colorado and Children's Hospital Colorado, Aurora, Colorado
| | - Suhong Tong
- Department of Pediatrics, Research Institute Biostatistics Core, University of Colorado and Children's Hospital Colorado, Aurora, Colorado
| | - Curtis R Coughlin
- Department of Pediatrics, Section of Clinical Genetics and Metabolism, University of Colorado, Aurora, Colorado
| | - Julia B Hennermann
- Department of Pediatric and Adolescent Medicine, University Medical Center Mainz, Mainz, Germany
| | - Saskia B Wortmann
- Department of Pediatrics, Salzburger Landeskliniken (SALK) und Paracelsus Medical University (PMU) Salzburg, Salzburg, Austria
| | - Johan L K Van Hove
- Department of Pediatrics, Section of Clinical Genetics and Metabolism, University of Colorado, Aurora, Colorado
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31
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Arya S, Melton K. Case 2: Seizures, Apnea, Lethargy, and Persistent Hiccups in a Full-Term Newborn. Neoreviews 2019; 20:e295-e297. [PMID: 31261082 DOI: 10.1542/neo.20-5-e295] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Affiliation(s)
- Shreyas Arya
- Neonatology and Pulmonary Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH
| | - Kristin Melton
- Neonatology and Pulmonary Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH
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Abstract
Inborn errors of metabolism, also known as inherited metabolic diseases, constitute an important group of conditions presenting with neurologic signs in newborns. They are individually rare but collectively common. Many are treatable through restoration of homeostasis of a disrupted metabolic pathway. Given their frequency and potential for treatment, the clinician should be aware of this group of conditions and learn to identify the typical manifestations of the different inborn errors of metabolism. In this review, we summarize the clinical, laboratory, electrophysiologic, and neuroimaging findings of the different inborn errors of metabolism that can present with florid neurologic signs and symptoms in the neonatal period.
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MESH Headings
- Adult
- Female
- Humans
- Infant, Newborn
- Infant, Newborn, Diseases/diagnosis
- Infant, Newborn, Diseases/diagnostic imaging
- Infant, Newborn, Diseases/physiopathology
- Infant, Newborn, Diseases/therapy
- Metabolism, Inborn Errors/diagnosis
- Metabolism, Inborn Errors/diagnostic imaging
- Metabolism, Inborn Errors/physiopathology
- Metabolism, Inborn Errors/therapy
- Neuroimaging
- Pregnancy
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Affiliation(s)
- Carlos R Ferreira
- Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, United States; Rare Disease Institute, Children's National Health System, Washington, DC, United States
| | - Clara D M van Karnebeek
- Departments of Pediatrics and Clinical Genetics, Amsterdam University Medical Centers, Amsterdam, The Netherlands; Department of Pediatrics, Centre for Molecular Medicine and Therapeutics, University of British Columbia, Vancouver, BC, Canada.
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Abstract
Although the majority of seizures in neonates are related to acute brain injury, a substantial minority are the first symptom of a neonatal-onset epilepsy often linked to a pathogenic genetic variant. Historically, studies on neonatal seizures including treatment response and long-term consequences have lumped all etiologies together. However, etiology has been consistently shown to be the most important determinant of outcome. In the past few years, an increasing number of monogenic disorders have been described and might explain up to a third of neonatal-onset epilepsy syndromes previously included under the umbrella of Ohtahara syndrome and early myoclonic encephalopathy. In this chapter, we define the concept of genetic epilepsy and review the classification. Then, we review the most relevant monogenic neonatal-onset epilepsies, detail their underlying pathophysiologic mechanisms, and present their electroclinical phenotypes. We highlight that, in some cases, such as neonates with KCNQ2 or KCNT1 gene mutations, the early recognition of the electroclinical phenotype can lead to targeted diagnostic testing and precision medicine treatment, enabling the possibility of improved outcome.
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34
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Kölker S. Metabolism of amino acid neurotransmitters: the synaptic disorder underlying inherited metabolic diseases. J Inherit Metab Dis 2018; 41:1055-1063. [PMID: 29869166 DOI: 10.1007/s10545-018-0201-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Revised: 05/09/2018] [Accepted: 05/14/2018] [Indexed: 10/14/2022]
Abstract
Amino acids are involved in various metabolic pathways and some of them also act as neurotransmitters. Since biosynthesis of L-glutamate and γ-aminobutyric acid (GABA) requires 2-oxoglutarate while 3-phosphoglycerate is the precursor of L-glycine and D-serine, evolutionary selection of these amino acid neurotransmitters might have been driven by their capacity to provide important information about the glycolytic pathway and Krebs cycle. Synthesis and recycling of amino acid neurotransmitters as well as composition and function of their receptors are often compromised in inherited metabolic diseases. For instance, increased plasma L-phenylalanine concentrations impair cerebral biosynthesis of protein and bioamines in phenylketonuria, while elevated cerebral L-phenylalanine directly acts via ionotropic glutamate receptors. In succinic semialdehyde dehydrogenase deficiency, the neurotransmitter GABA and neuromodulatory γ-hydroxybutyric acid are elevated. Chronic hyperGABAergic state results in progressive downregulation of GABAA and GABAB receptors and impaired mitophagy. In glycine encephalopathy, the neurological phenotype is precipitated by L-glycine acting both via cortical NMDA receptors and glycine receptors in spinal cord and brain stem neurons. Serine deficiency syndromes are biochemically characterized by decreased biosynthesis of L-serine, an important neurotrophic factor, and the neurotransmitters D-serine and L-glycine. Supplementation with L-serine and L-glycine has a positive effect on seizure frequency and spasticity, while neurocognitive development can only be improved if treatment starts in utero or immediately postnatally. With novel techniques, the study of synaptic dysfunction in inherited metabolic diseases has become an emerging research field. More and better therapies are needed for these difficult-to-treat diseases.
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Affiliation(s)
- Stefan Kölker
- Division of Pediatric Neurology and Metabolic Medicine, Centre for Pediatric and Adolescent Medicine, University Hospital Heidelberg, Im Neuenheimer Feld 430, 69120, Heidelberg, Germany.
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35
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Why does hyperglycinemia exhibit so grave brain anomalies and so severe neurological symptoms? J Theor Biol 2018; 455:97-100. [DOI: 10.1016/j.jtbi.2018.07.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Revised: 07/06/2018] [Accepted: 07/09/2018] [Indexed: 11/23/2022]
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Abstract
West syndrome (WS) is an early life epileptic encephalopathy associated with infantile spasms, interictal electroencephalography (EEG) abnormalities including high amplitude, disorganized background with multifocal epileptic spikes (hypsarrhythmia), and often neurodevelopmental impairments. Approximately 64% of the patients have structural, metabolic, genetic, or infectious etiologies and, in the rest, the etiology is unknown. Here we review the contribution of etiologies due to various metabolic disorders in the pathology of WS. These may include metabolic errors in organic molecules involved in amino acid and glucose metabolism, fatty acid oxidation, metal metabolism, pyridoxine deficiency or dependency, or acidurias in organelles such as mitochondria and lysosomes. We discuss the biochemical, clinical, and EEG features of these disorders as well as the evidence of how they may be implicated in the pathogenesis and treatment of WS. The early recognition of these etiologies in some cases may permit early interventions that may improve the course of the disease.
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Affiliation(s)
- Seda Salar
- Laboratory of Developmental EpilepsySaul R. Korey Department of NeurologyMontefiore/Einstein Epilepsy CenterAlbert Einstein College of MedicineBronxNew YorkU.S.A.
| | - Solomon L. Moshé
- Laboratory of Developmental EpilepsySaul R. Korey Department of NeurologyMontefiore/Einstein Epilepsy CenterAlbert Einstein College of MedicineBronxNew YorkU.S.A.
- Dominick P. Purpura Department of NeuroscienceMontefiore/Einstein Epilepsy CenterAlbert Einstein College of MedicineBronxNew YorkU.S.A.
- Department of PediatricsMontefiore/Einstein Epilepsy CenterAlbert Einstein College of MedicineBronxNew YorkU.S.A.
| | - Aristea S. Galanopoulou
- Laboratory of Developmental EpilepsySaul R. Korey Department of NeurologyMontefiore/Einstein Epilepsy CenterAlbert Einstein College of MedicineBronxNew YorkU.S.A.
- Dominick P. Purpura Department of NeuroscienceMontefiore/Einstein Epilepsy CenterAlbert Einstein College of MedicineBronxNew YorkU.S.A.
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Bezafibrate Prevents Glycine-Induced Increase of Antioxidant Enzyme Activities in Rat Striatum. Mol Neurobiol 2018; 56:29-38. [DOI: 10.1007/s12035-018-1074-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Accepted: 04/10/2018] [Indexed: 02/03/2023]
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Abdel Maksoud M, ELsayed SM, Shatla RH, Imam AA, Elsayed RM, Mosabah AA, Sherif AM. Frequency of inborn errors of metabolism screening for children with unexplained acute encephalopathy at an emergency department. Neuropsychiatr Dis Treat 2018; 14:1715-1720. [PMID: 29988750 PMCID: PMC6029674 DOI: 10.2147/ndt.s165833] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
OBJECTIVE Our study aimed to estimate the frequency of inborn errors of metabolism (IEMs) in patients presenting with acute encephalopathy-like picture at an emergency department (ED). SUBJECTS AND METHODS Our study was a prospective observational study conducted on 30 patients admitted to the pediatric ED with unexplained acute encephalopathy. The study included 30 children with an age ranging from 1 month to 5 years. All patients were subjected to full history taking, thorough clinical examination, and laboratory investigations including serum ammonia, serum lactate, arterial blood gases, tandem mass spectroscopy, organic acid of urine, cerebrospinal fluid examination to exclude central nervous system infection plus the routine laboratory tests (kidney functions, liver functions, random blood glucose, complete blood picture), and brain imaging computed tomography and/or magnetic resonance imaging brain. RESULTS Thirty children presented with acute encephalopathy at the ED. All were screened for suspected IEMs. Ten (33.3%) of them was positive in the initial screening test. There were four (13.3%) patients with possible mitochondrial diseases, four (13.3%) patients with possible organic acidemia, one (3.3%) patient with possible urea cycle defect, and one (3.3%) patient with possible nonketotic hyperglycinemia. CONCLUSION Any case of unexplained acute encephalopathy presenting to the ED should be investigated for suspected IEM, especially in high-risk families, as early interventions will lead to improved outcome.
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Affiliation(s)
| | | | - Rania H Shatla
- Pediatric Department, Ain Shams University, Cairo, Egypt
| | | | - Riad M Elsayed
- Pediatric Neurology Unit, Pediatric Department, Mansoura University, Mansoura, Dakahlia, Egypt,
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Neuroimaging of Pediatric Metabolic Disorders with Emphasis on Diffusion-Weighted Imaging and MR Spectroscopy: A Pictorial Essay. CURRENT RADIOLOGY REPORTS 2017. [DOI: 10.1007/s40134-017-0251-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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40
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Mohammad SA, Abdelkhalek HS. Nonketotic hyperglycinemia: spectrum of imaging findings with emphasis on diffusion-weighted imaging. Neuroradiology 2017; 59:1155-1163. [PMID: 28864914 DOI: 10.1007/s00234-017-1913-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2017] [Accepted: 08/22/2017] [Indexed: 11/26/2022]
Abstract
PURPOSE The purpose of this study was to explore brain abnormalities in nonketotic hyperglycinemia (NKH) using diffusion-weighted imaging (DWI) and when feasible, diffusion tensor imaging (DTI) and tractography. METHODS Seven patients with confirmed diagnosis of NKH (8 days-2 years) underwent brain MRI. Conventional T1 and T2WI were acquired in all patients, DWI in six and DTI and tractography in two (4 months and 2 years). Measurements of fractional anisotropy (FA), radial diffusivity (RD), axial diffusivity (AD) and Trace from eight white matter regions were compared between the two patients and age-matched controls. Tractography of corpus callosum, superior longitudinal fasciculus and corticospinal tracts was performed with extraction of their FA and diffusivity indices. RESULTS MRI showed nonspecific brain atrophy in three children. Corpus callosum atrophy was found as a part of these atrophic changes. Cerebellar vermian hypoplasia and supratentorial hydrocephalus were seen in one patient. The topographic distribution of diffusion restriction was different among patients. The affected white matter regions were not predominantly following the expected areas of myelination according to patients' age. Deep grey matter nuclei were affected in one patient. DTI revealed lower FA with higher RD in most of the measured white matter regions and tracts. These changes were more appreciated in the 2-year-old patient. However, Trace was higher in the 2-year-old patient and lower in the 4-month-old one. The extracted tracts were decreased in volume. CONCLUSION DWI, DTI and tractography with FA and diffusivity measurements can give insights into white matter microstructural alterations that can occur in NKH.
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Affiliation(s)
- Shaimaa Abdelsattar Mohammad
- Radiodiagnosis Department, Faculty of Medicine, Ain-Shams University, 9 Lotfi Elsayed St. Ain-Shams University Staff Buildings, Cairo, 11657, Egypt.
| | - Heba Salah Abdelkhalek
- Medical Genetics Unit, Pediatric Department, Faculty of Medicine, Ain-Shams University, Cairo, Egypt
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Clinical heterogeneity of glycine encephalopathy in three Palestinian siblings: A novel mutation in the glycine decarboxylase (GLDC) gene. Brain Dev 2017; 39:601-605. [PMID: 28325525 DOI: 10.1016/j.braindev.2017.03.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 02/02/2017] [Accepted: 03/02/2017] [Indexed: 12/31/2022]
Abstract
INTRODUCTION Glycine encephalopathy (GE), also known as non-ketotic hyperglycinemia (NKH), is a rare inborn error of glycine metabolism caused by a defect in glycine cleavage system, a multi-enzyme complex located in mitochondrial membrane. This defect results in elevated glycine concentration in plasma and cerebrospinal fluid (CSF). Clinical manifestations vary from severe lethargy, hypoactivity and apneic episodes in the neonatal form, mild or moderate psychomotor delay and seizures in the infantile form, and abnormal behaviors, ataxia and choreoathetoid movements in late onset form. More than 50 GLDC mutations were found, reflecting large heterogeneity of the gene. METHODS We describe the clinical, biochemical and molecular characteristics of three Palestinian siblings who have distinct clinical phenotypes. Molecular study was performed utilizing standard Polymerase Chain Reaction (PCR) amplification then direct DNA sequencing for the affected family members. RESULTS Their phenotypes included severe symptoms in neonatal period, infantile onset of seizure and psychomotor delay and a mild late-onset form with speech delay at age 20months. All siblings were homozygous for a novel mutation Y164H in exon 4 of GLDC gene. The described novel homozygous variant in our study is predicted deleterious and pathogenic. CONCLUSIONS This article further expands the genetic spectrum of glycine encephalopathy and adds an evidence of the clinical heterogeneity of glycine encephalopathy even in siblings with identical mutation.
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Abstract
OPINION STATEMENT In the absence of a culprit epileptogenic lesion, pharmacoresistant seizures should prompt the physician to consider potentially treatable metabolic epilepsies, especially in the presence of developmental delays. Even though the anti-seizure treatment of the epilepsies remains symptomatic and usually tailored to an electroclinical phenotype rather than to an underlying etiology, a thorough metabolic workup might reveal a disease with an etiology-specific treatment. Early diagnosis is essential in the case of treatable metabolic epilepsies allowing timely intervention. Despite the advances in genetic testing, biochemical testing including cerebrospinal fluid studies are still needed to expedite the diagnostic workup and potential therapeutic trials. The diagnostician should have a high index of suspicion despite potential clinical digressions from seminal publications describing the initial cases, as these index patients may represent the most severe form of the condition rather than its most common presenting form. The often gratifying developmental outcome and seizure control with early treatment calls for a prompt diagnostic consideration of treatable metabolic diseases; even though relatively rare or potentially only seemingly so.
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Scalais E, Osterheld E, Weitzel C, De Meirleir L, Mataigne F, Martens G, Shaikh TH, Coughlin CR, Yu HC, Swanson M, Friederich MW, Scharer G, Helbling D, Wendt-Andrae J, Van Hove JLK. X-Linked Cobalamin Disorder (HCFC1) Mimicking Nonketotic Hyperglycinemia With Increased Both Cerebrospinal Fluid Glycine and Methylmalonic Acid. Pediatr Neurol 2017; 71:65-69. [PMID: 28363510 DOI: 10.1016/j.pediatrneurol.2016.12.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/27/2016] [Revised: 11/23/2016] [Accepted: 12/03/2016] [Indexed: 12/13/2022]
Abstract
BACKGROUND Autosomal recessive or X-linked inborn errors of intracellular cobalamin metabolism can lead to methylmalonic aciduria and homocystinuria. In neonates, both increased cerebrospinal fluid glycine and cerebrospinal fluid/plasma glycine ratio are biochemical features of nonketotic hyperglycinemia. METHODS We describe a boy presenting in the neonatal period with hypotonia, tonic, clonic, and later myoclonic seizures, subsequently evolving into refractory epilepsy and severe neurocognitive impairment. RESULTS Increased cerebrospinal fluid glycine and cerebrospinal fluid to plasma glycine ratio were indicative of nonketotic hyperglycinemia. Early magnetic resonance imaging showed restricted diffusion and decreased apparent diffusion coefficient values in posterior limb of internal capsules and later in entire internal capsules and posterior white matter. Sequencing did not show a mutation in AMT, GLDC, or GCSH. Biochemical analysis identified persistently increased cerebrospinal fluid levels of glycine and methylmalonic acid and increased urinary methylmalonic acid and plasma homocysteine levels, which improved on higher parenteral hydroxocobalamin dose. Exome sequencing identified a known pathogenic sequence variant in X-linked cobalamin (HCFC1), c.344C>T, p. Ala115Val. In addition, a hemizygous mutation was found in the ATRX (c. 2728A>G, p. Lys910Glu). Retrospective review of two other patients with X-linked cobalamin deficiency also identified increased cerebrospinal fluid glycine levels. CONCLUSIONS This boy had X-linked cobalamin deficiency (HCFC1) with increased cerebrospinal fluid glycine and methylmalonic acid and increased cerebrospinal fluid to plasma glycine ratio suggesting a brain hyperglycinemia. Putative binding sites for HCFC1 and its binding partner THAP11 were identified near genes of the glycine cleavage enzyme, providing a potential mechanistic link between HCFC1 mutations and increased glycine.
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Affiliation(s)
- Emmanuel Scalais
- Division of Pediatric Neurology, Centre Hospitalier de Luxembourg, Luxembourg, Luxembourg; Department of Pediatrics, Centre Hospitalier de Luxembourg, Luxembourg, Luxembourg.
| | - Elise Osterheld
- Division of Pediatric Neurology, Centre Hospitalier de Luxembourg, Luxembourg, Luxembourg; Department of Pediatrics, Centre Hospitalier de Luxembourg, Luxembourg, Luxembourg
| | - Christiane Weitzel
- Department of Pediatrics, Centre Hospitalier de Luxembourg, Luxembourg, Luxembourg
| | - Linda De Meirleir
- Pediatric Neurology and Metabolism, Universitair Ziekenhuis, Brussel, Belgium
| | - Frederic Mataigne
- Department of Neuroradiology, Centre Hospitalier de Luxembourg, Luxembourg, Luxembourg
| | - Geert Martens
- VUB Metabolomics Platform, Department of Clinical Biology, Universitair Ziekenhuis, Brussel, Belgium
| | - Tamim H Shaikh
- Department of Pediatrics, University of Colorado, School of Medicine, Aurora, Colorado
| | - Curtis R Coughlin
- Department of Pediatrics, University of Colorado, School of Medicine, Aurora, Colorado
| | - Hung-Chun Yu
- Department of Pediatrics, University of Colorado, School of Medicine, Aurora, Colorado
| | - Michael Swanson
- Department of Pediatrics, University of Colorado, School of Medicine, Aurora, Colorado
| | - Marisa W Friederich
- Department of Pediatrics, University of Colorado, School of Medicine, Aurora, Colorado
| | - Gunter Scharer
- Department of Pediatrics, Medical College of Wisconsin, Milwaukee, Wisconsin; Molecular Genetics Supervisor, Sequencing Core Diagnostic Manager, Human Molecular Genetics Center, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Daniel Helbling
- Molecular Genetics Supervisor, Sequencing Core Diagnostic Manager, Human Molecular Genetics Center, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Jamie Wendt-Andrae
- Molecular Genetics Supervisor, Sequencing Core Diagnostic Manager, Human Molecular Genetics Center, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Johan L K Van Hove
- Department of Pediatrics, University of Colorado, School of Medicine, Aurora, Colorado.
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Ascenzi M, Bony G. The building of the neocortex with non-hyperpolarizing neurotransmitters. Dev Neurobiol 2017; 77:1023-1037. [PMID: 28276653 DOI: 10.1002/dneu.22495] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Revised: 02/16/2017] [Accepted: 02/28/2017] [Indexed: 12/12/2022]
Abstract
The development of the neocortex requires the synergic action of several secreted molecules to achieve the right amount of proliferation, differentiation, and migration of neural cells. Neurons are well known to release neurotransmitters (NTs) in adult and a growing body of evidences describes the presence of NTs already in the embryonic brain, long before the generation of synapses. NTs are classified as inhibitory or excitatory based on the physiological responses of the target neuron. However, this view is challenged by the fact that glycine and GABA NTs are excitatory during development. Many reviews have described the role of nonhyperpolarizing GABA at this stage. Nevertheless, a global consideration of the inhibitory neurotransmitters and their downstream signaling during the embryonic cortical development is still needed. For example, taurine, the most abundant neurotransmitter during development is poorly studied regarding its role during cortical development. In the light of recent discoveries, we will discuss the functions of glycine, GABA, and taurine during embryonic cortical development with an emphasis on their downstream signaling. © 2017 Wiley Periodicals, Inc. Develop Neurobiol 77: 1023-1037, 2017.
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Affiliation(s)
| | - Guillaume Bony
- INSERM U1215, NeuroCentre Magendie, Bordeaux, France.,Université de Bordeaux, NeuroCentre Magendie, Bordeaux, France
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45
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Bravo-Alonso I, Navarrete R, Arribas-Carreira L, Perona A, Abia D, Couce ML, García-Cazorla A, Morais A, Domingo R, Ramos MA, Swanson MA, Van Hove JLK, Ugarte M, Pérez B, Pérez-Cerdá C, Rodríguez-Pombo P. Nonketotic hyperglycinemia: Functional assessment of missense variants in GLDC to understand phenotypes of the disease. Hum Mutat 2017; 38:678-691. [PMID: 28244183 DOI: 10.1002/humu.23208] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Revised: 02/22/2017] [Accepted: 02/23/2017] [Indexed: 11/08/2022]
Abstract
The rapid analysis of genomic data is providing effective mutational confirmation in patients with clinical and biochemical hallmarks of a specific disease. This is the case for nonketotic hyperglycinemia (NKH), a Mendelian disorder causing seizures in neonates and early-infants, primarily due to mutations in the GLDC gene. However, understanding the impact of missense variants identified in this gene is a major challenge for the application of genomics into clinical practice. Herein, a comprehensive functional and structural analysis of 19 GLDC missense variants identified in a cohort of 26 NKH patients was performed. Mutant cDNA constructs were expressed in COS7 cells followed by enzymatic assays and Western blot analysis of the GCS P-protein to assess the residual activity and mutant protein stability. Structural analysis, based on molecular modeling of the 3D structure of GCS P-protein, was also performed. We identify hypomorphic variants that produce attenuated phenotypes with improved prognosis of the disease. Structural analysis allows us to interpret the effects of mutations on protein stability and catalytic activity, providing molecular evidence for clinical outcome and disease severity. Moreover, we identify an important number of mutants whose loss-of-functionality is associated with instability and, thus, are potential targets for rescue using folding therapeutic approaches.
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Affiliation(s)
- Irene Bravo-Alonso
- Centro de Diagnóstico de Enfermedades Moleculares, Centro de Biología Molecular Severo Ochoa, CBM-CSIC, Departamento de Biología Molecular, Universidad Autónoma Madrid, Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), IDIPAZ, Madrid, Spain
| | - Rosa Navarrete
- Centro de Diagnóstico de Enfermedades Moleculares, Centro de Biología Molecular Severo Ochoa, CBM-CSIC, Departamento de Biología Molecular, Universidad Autónoma Madrid, Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), IDIPAZ, Madrid, Spain
| | - Laura Arribas-Carreira
- Centro de Diagnóstico de Enfermedades Moleculares, Centro de Biología Molecular Severo Ochoa, CBM-CSIC, Departamento de Biología Molecular, Universidad Autónoma Madrid, Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), IDIPAZ, Madrid, Spain
| | | | - David Abia
- Servicio de Bioinformática, Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Madrid, Spain
| | - María Luz Couce
- Unit of Diagnosis and Treatment of Congenital Metabolic Diseases, Service of Neonatology, Department of Pediatrics, Hospital Clínico Universitario de Santiago, CIBERER, Health Research Institute of Santiago de Compostela (IDIS), Santiago de Compostela, Spain
| | - Angels García-Cazorla
- Institut de Recerca Pediàtrica-Hospital Sant Joan de Déu (IRP-HSJD), Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III, Barcelona, Spain
| | - Ana Morais
- Unidad de Nutrición Infantil y Enfermedades Metabólicas, Hospital Universitario Infantil La Paz, Madrid, Spain
| | - Rosario Domingo
- Servicio de Pediatría, Hospital Virgen de la Arrixaca, Murcia, Spain
| | - María Antonia Ramos
- Servicio de Genética, Hospital B del Complejo Hospitalario de Navarra, Pamplona, Navarra, Spain
| | - Michael A Swanson
- Department of Pediatrics, Section of Clinical Genetics and Metabolism, University of Colorado, Aurora, Colorado
| | - Johan L K Van Hove
- Department of Pediatrics, Section of Clinical Genetics and Metabolism, University of Colorado, Aurora, Colorado
| | - Magdalena Ugarte
- Centro de Diagnóstico de Enfermedades Moleculares, Centro de Biología Molecular Severo Ochoa, CBM-CSIC, Departamento de Biología Molecular, Universidad Autónoma Madrid, Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), IDIPAZ, Madrid, Spain
| | - Belén Pérez
- Centro de Diagnóstico de Enfermedades Moleculares, Centro de Biología Molecular Severo Ochoa, CBM-CSIC, Departamento de Biología Molecular, Universidad Autónoma Madrid, Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), IDIPAZ, Madrid, Spain
| | - Celia Pérez-Cerdá
- Centro de Diagnóstico de Enfermedades Moleculares, Centro de Biología Molecular Severo Ochoa, CBM-CSIC, Departamento de Biología Molecular, Universidad Autónoma Madrid, Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), IDIPAZ, Madrid, Spain
| | - Pilar Rodríguez-Pombo
- Centro de Diagnóstico de Enfermedades Moleculares, Centro de Biología Molecular Severo Ochoa, CBM-CSIC, Departamento de Biología Molecular, Universidad Autónoma Madrid, Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), IDIPAZ, Madrid, Spain
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46
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Li HF. [Clinical and molecular genetic characteristics of nonketotic hyperglycinemia]. ZHONGGUO DANG DAI ER KE ZA ZHI = CHINESE JOURNAL OF CONTEMPORARY PEDIATRICS 2017; 19:272-274. [PMID: 28302195 PMCID: PMC7390138 DOI: 10.7499/j.issn.1008-8830.2017.03.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Received: 11/06/2016] [Accepted: 12/20/2016] [Indexed: 06/06/2023]
Affiliation(s)
- Hai-Feng Li
- Department of Rehabilitation, Children's Hospital, Zhejiang University School of Medicine, Hangzhou 310003, China
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47
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Autuori MC, Pai YJ, Stuckey DJ, Savery D, Marconi AM, Massa V, Lythgoe MF, Copp AJ, David AL, Greene NDE. Use of high-frequency ultrasound to study the prenatal development of cranial neural tube defects and hydrocephalus in Gldc-deficient mice. Prenat Diagn 2017; 37:273-281. [PMID: 28056489 PMCID: PMC5347903 DOI: 10.1002/pd.5004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Revised: 12/16/2016] [Accepted: 12/29/2016] [Indexed: 12/05/2022]
Abstract
Objective We used non‐invasive high‐frequency ultrasound (HFUS) imaging to investigate embryonic brain development in a mouse model for neural tube defects (NTDs) and non‐ketotic hyperglycinemia (NKH). Method Using HFUS, we imaged embryos carrying loss of function alleles of Gldc encoding glycine decarboxylase, a component of the glycine cleavage system in mitochondrial folate metabolism, which is known to be associated with cranial NTDs and NKH in humans. We serially examined the same litter during the second half of embryonic development and quantified cerebral structures. Genotype was confirmed using PCR. Histology was used to confirm ultrasound findings. Results High‐frequency ultrasound allowed in utero detection of two major brain abnormalities in Gldc‐deficient mouse embryos, cranial NTDs (exencephaly) and ventriculomegaly (corresponding with the previous finding of post‐natal hydrocephalus). Serial ultrasound allowed individual embryos to be analysed at successive gestational time points. From embryonic day 16.5 to 18.5, the lateral ventricle volume reduced in wild‐type and heterozygous embryos but increased in homozygous Gldc‐deficient embryos. Conclusion Exencephaly and ventriculomegaly were detectable by HFUS in homozygous Gldc‐deficient mouse embryos indicating this to be an effective tool to study CNS development. Longitudinal analysis of the same embryo allowed the prenatal onset and progression of ventricle enlargement in Gldc‐deficient mice to be determined. © 2017 The Authors. Prenatal Diagnosis published by John Wiley & Sons, Ltd. What's already known about this topic?High‐frequency ultrasound (HFUS) has been used to non‐invasively monitor in utero mouse central nervous system (CNS) development during mid‐gestation (embryonic day 10.5–14.5); later gestational ages are yet to be studied. Missense mutations of the glycine decarboxylase gene (Gldc) are associated clinically with a metabolic disorder, Non‐ketotic hyperglycinemia (NKH) and neural tube defects (NTDs) such as exencephaly.
What does this study add?We extended HFUS imaging of the mouse CNS into late gestation embryonic day 18.5 in a genetic mouse mutant lacking Gldc in which NTDs, such as exencephaly, and hydrocephalus are prevalent. Serial HFUS can determine the age of onset of ventricle dilation that precedes hydrocephalus in this model.
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Affiliation(s)
- Maria C Autuori
- Newlife Birth Defects Research Centre and Developmental Biology and Cancer Programme, Great Ormond Street Institute of Child Health, University College London, London, UK.,Department of Obstetrics and Gynaecology, San Paolo Hospital, Milan, Italy
| | - Yun J Pai
- Newlife Birth Defects Research Centre and Developmental Biology and Cancer Programme, Great Ormond Street Institute of Child Health, University College London, London, UK
| | - Daniel J Stuckey
- Centre for Advanced Biomedical Imaging, University College London, London, UK
| | - Dawn Savery
- Newlife Birth Defects Research Centre and Developmental Biology and Cancer Programme, Great Ormond Street Institute of Child Health, University College London, London, UK
| | - Anna M Marconi
- Department of Obstetrics and Gynaecology, San Paolo Hospital, Milan, Italy
| | - Valentina Massa
- Department of Health Science, San Paolo Hospital, Milan, Italy
| | - Mark F Lythgoe
- Centre for Advanced Biomedical Imaging, University College London, London, UK
| | - Andrew J Copp
- Newlife Birth Defects Research Centre and Developmental Biology and Cancer Programme, Great Ormond Street Institute of Child Health, University College London, London, UK
| | - Anna L David
- Maternal and Fetal Medicine, Institute for Women's Health, University College London, London, UK
| | - Nicholas D E Greene
- Newlife Birth Defects Research Centre and Developmental Biology and Cancer Programme, Great Ormond Street Institute of Child Health, University College London, London, UK
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48
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The genetic basis of classic nonketotic hyperglycinemia due to mutations in GLDC and AMT. Genet Med 2016; 19:104-111. [PMID: 27362913 DOI: 10.1038/gim.2016.74] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Accepted: 04/25/2016] [Indexed: 11/09/2022] Open
Abstract
PURPOSE The study's purpose was to delineate the genetic mutations that cause classic nonketotic hyperglycinemia (NKH). METHODS Genetic results, parental phase, ethnic origin, and gender data were collected from subjects suspected to have classic NKH. Mutations were compared with those in the existing literature and to the population frequency from the Exome Aggregation Consortium (ExAC) database. RESULTS In 578 families, genetic analyses identified 410 unique mutations, including 246 novel mutations. 80% of subjects had mutations in GLDC. Missense mutations were noted in 52% of all GLDC alleles, most private. Missense mutations were 1.5 times as likely to be pathogenic in the carboxy terminal of GLDC than in the amino-terminal part. Intragenic copy-number variations (CNVs) in GLDC were noted in 140 subjects, with biallelic CNVs present in 39 subjects. The position and frequency of the breakpoint for CNVs correlated with intron size and presence of Alu elements. Missense mutations, most often recurring, were the most common type of disease-causing mutation in AMT. Sequencing and CNV analysis identified biallelic pathogenic mutations in 98% of subjects. Based on genotype, 15% of subjects had an attenuated phenotype. The frequency of NKH is estimated at 1:76,000. CONCLUSION The 484 unique mutations now known in classic NKH provide a valuable overview for the development of genotype-based therapies.Genet Med 19 1, 104-111.
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Nickerson SL, Balasubramaniam S, Dryland PA, Love JM, Kava MP, Love DR, Prosser DO. Two Novel GLDC Mutations in a Neonate with Nonketotic Hyperglycinemia. J Pediatr Genet 2016; 5:174-80. [PMID: 27617160 DOI: 10.1055/s-0036-1584358] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Accepted: 09/09/2015] [Indexed: 10/21/2022]
Abstract
Nonketotic hyperglycinemia, also known as glycine encephalopathy (OMIM #605899), is an autosomal recessive disorder of glycine metabolism resulting from a defect in the glycine cleavage system. We report two novel mutations of the glycine decarboxylase (GLDC) gene observed in a compound heterozygous state in a neonate of mixed Maori and Caucasian parentage: c.395C>T p.(Ser132Leu) in exon 3, and c.256-?_334+?del p.(Ser86Valfs*119), resulting in an out-of-frame deletion of exon 2. Additionally, we describe our experience of implementing the ketogenic diet, alongside standard pharmacological therapy, and highlight its potential therapeutic benefit in severe nonketotic hyperglycinemia, particularly in seizure management.
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Affiliation(s)
- Sarah L Nickerson
- Diagnostic Genetics, LabPLUS, Auckland City Hospital, Auckland, New Zealand
| | - Shanti Balasubramaniam
- Metabolic Unit, Department of Rheumatology/Metabolic Medicine, Princess Margaret Hospital, Perth, WA, Australia; School of Paediatrics and Child Health, University of Western Australia, WA, Australia
| | - Philippa A Dryland
- Diagnostic Genetics, LabPLUS, Auckland City Hospital, Auckland, New Zealand
| | - Jennifer M Love
- Diagnostic Genetics, LabPLUS, Auckland City Hospital, Auckland, New Zealand
| | - Maina P Kava
- School of Paediatrics and Child Health, University of Western Australia, WA, Australia; Department of Paediatric Neurology, Princess Margaret Hospital for Children, Perth, WA, Australia
| | - Donald R Love
- Diagnostic Genetics, LabPLUS, Auckland City Hospital, Auckland, New Zealand
| | - Debra O Prosser
- Diagnostic Genetics, LabPLUS, Auckland City Hospital, Auckland, New Zealand
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50
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Abstract
Radical S-adenosylmethionine (SAM) enzymes catalyze an astonishing array of complex and chemically challenging reactions across all domains of life. Of approximately 114,000 of these enzymes, 8 are known to be present in humans: MOCS1, molybdenum cofactor biosynthesis; LIAS, lipoic acid biosynthesis; CDK5RAP1, 2-methylthio-N(6)-isopentenyladenosine biosynthesis; CDKAL1, methylthio-N(6)-threonylcarbamoyladenosine biosynthesis; TYW1, wybutosine biosynthesis; ELP3, 5-methoxycarbonylmethyl uridine; and RSAD1 and viperin, both of unknown function. Aberrations in the genes encoding these proteins result in a variety of diseases. In this review, we summarize the biochemical characterization of these 8 radical S-adenosylmethionine enzymes and, in the context of human health, describe the deleterious effects that result from such genetic mutations.
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Affiliation(s)
- Bradley J Landgraf
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802
| | - Erin L McCarthy
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802
| | - Squire J Booker
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802.,Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802.,The Howard Hughes Medical Institute, The Pennsylvania State University, University Park, Pennsylvania 16802;
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