1
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Frye RE, Rincon N, McCarty PJ, Brister D, Scheck AC, Rossignol DA. Biomarkers of mitochondrial dysfunction in autism spectrum disorder: A systematic review and meta-analysis. Neurobiol Dis 2024; 197:106520. [PMID: 38703861 DOI: 10.1016/j.nbd.2024.106520] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2024] [Revised: 04/27/2024] [Accepted: 04/29/2024] [Indexed: 05/06/2024] Open
Abstract
Autism spectrum disorder (ASD) is a neurodevelopmental disorder affecting 1 in 36 children and is associated with physiological abnormalities, most notably mitochondrial dysfunction, at least in a subset of individuals. This systematic review and meta-analysis discovered 204 relevant articles which evaluated biomarkers of mitochondrial dysfunction in ASD individuals. Significant elevations (all p < 0.01) in the prevalence of lactate (17%), pyruvate (41%), alanine (15%) and creatine kinase (9%) were found in ASD. Individuals with ASD had significant differences (all p < 0.01) with moderate to large effect sizes (Cohen's d' ≥ 0.6) compared to controls in mean pyruvate, lactate-to-pyruvate ratio, ATP, and creatine kinase. Some studies found abnormal TCA cycle metabolites associated with ASD. Thirteen controlled studies reported mitochondrial DNA (mtDNA) deletions or variations in the ASD group in blood, peripheral blood mononuclear cells, lymphocytes, leucocytes, granulocytes, and brain. Meta-analyses discovered significant differences (p < 0.01) in copy number of mtDNA overall and in ND1, ND4 and CytB genes. Four studies linked specific mtDNA haplogroups to ASD. A series of studies found a subgroup of ASD with elevated mitochondrial respiration which was associated with increased sensitivity of the mitochondria to physiological stressors and neurodevelopmental regression. Lactate, pyruvate, lactate-to-pyruvate ratio, carnitine, and acyl-carnitines were associated with clinical features such as delays in language, social interaction, cognition, motor skills, and with repetitive behaviors and gastrointestinal symptoms, although not all studies found an association. Lactate, carnitine, acyl-carnitines, ATP, CoQ10, as well as mtDNA variants, heteroplasmy, haplogroups and copy number were associated with ASD severity. Variability was found across biomarker studies primarily due to differences in collection and processing techniques as well as the intrinsic heterogeneity of the ASD population. Several studies reported alterations in mitochondrial metabolism in mothers of children with ASD and in neonates who develop ASD. Treatments targeting mitochondria, particularly carnitine and ubiquinol, appear beneficial in ASD. The link between mitochondrial dysfunction in ASD and common physiological abnormalities in individuals with ASD including gastrointestinal disorders, oxidative stress, and immune dysfunction is outlined. Several subtypes of mitochondrial dysfunction in ASD are discussed, including one related to neurodevelopmental regression, another related to alterations in microbiome metabolites, and another related to elevations in acyl-carnitines. Mechanisms linking abnormal mitochondrial function with alterations in prenatal brain development and postnatal brain function are outlined. Given the multisystem complexity of some individuals with ASD, this review presents evidence for the mitochondria being central to ASD by contributing to abnormalities in brain development, cognition, and comorbidities such as immune and gastrointestinal dysfunction as well as neurodevelopmental regression. A diagnostic approach to identify mitochondrial dysfunction in ASD is outlined. From this evidence, it is clear that many individuals with ASD have alterations in mitochondrial function which may need to be addressed in order to achieve optimal clinical outcomes. The fact that alterations in mitochondrial metabolism may be found during pregnancy and early in the life of individuals who eventually develop ASD provides promise for early life predictive biomarkers of ASD. Further studies may improve the understanding of the role of the mitochondria in ASD by better defining subgroups and understanding the molecular mechanisms driving some of the unique changes found in mitochondrial function in those with ASD.
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Affiliation(s)
- Richard E Frye
- Autism Discovery and Treatment Foundation, Phoenix, AZ, USA; Southwest Autism Research and Resource Center, Phoenix, AZ, USA; Rossignol Medical Center, Phoenix, AZ, USA.
| | | | - Patrick J McCarty
- Tulane University School of Medicine, New Orleans, LA 70113, United States of America.
| | | | - Adrienne C Scheck
- Autism Discovery and Treatment Foundation, Phoenix, AZ, USA; Department of Child Health, University of Arizona College of Medicine - Phoenix, Phoenix, AZ 85004, United States of America.
| | - Daniel A Rossignol
- Autism Discovery and Treatment Foundation, Phoenix, AZ, USA; Rossignol Medical Center, Aliso Viejo, CA, USA
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2
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Boterberg S, Vantroys E, De Paepe B, Van Coster R, Roeyers H. Urine lactate concentration as a non-invasive screener for metabolic abnormalities: Findings in children with autism spectrum disorder and regression. PLoS One 2022; 17:e0274310. [PMID: 36084111 PMCID: PMC9462744 DOI: 10.1371/journal.pone.0274310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Accepted: 08/25/2022] [Indexed: 11/19/2022] Open
Abstract
There is increasing evidence that diseases caused by dysfunctional mitochondria (MD) are associated with autism spectrum disorder (ASD). A comprehensive meta-analysis showed that developmental regression was reported in half of the children with ASD and mitochondrial dysfunction which is much higher than in the general population of ASD. The aim of the present exploratory study was to determine lactate concentrations in urine of children with ASD, as a non-invasive large-scale screening method for metabolic abnormalities including mitochondrial dysfunction and its possible association with regression. First, clinical characteristics of MD were examined in 99 children (3–11 years) with ASD. Second, clinical characteristics of MD, severity of ASD and reported regression were compared between children with the 20% lowest lactate concentrations and those with the 20% highest lactate concentrations in urine. Third, clinical characteristics of MD and lactate concentration in urine were compared in children with (n = 37) and without (n = 62) reported regression. An association of urine lactate concentrations with mitochondrial dysfunction and regression could not be demonstrated in our large ASD cohort. However, since ASD children were reported by their parents to show a broad range of phenotypic characteristics of MD (e.g., gastro-intestinal and respiratory impairments), and lactate concentrations in urine are not always increased in individuals with MD, the presence of milder mitochondrial dysfunction cannot be excluded. Development of alternative biomarkers and their implementation in prospective studies following developmental trajectories of infants at elevated likelihood for ASD will be needed in the future to further unravel the association of ASD with mitochondrial dysfunction and eventually improve early detection.
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Affiliation(s)
- Sofie Boterberg
- Faculty of Psychology and Educational Sciences, Department of Experimental Clinical and Health Psychology, Research in Developmental Disorders Lab, Ghent University, Ghent, Belgium
- * E-mail:
| | - Elise Vantroys
- Faculty of Medicine and Health Sciences, Department of Internal Medicine and Paediatrics, Ghent University, Ghent, Belgium
| | - Boel De Paepe
- Faculty of Medicine and Health Sciences, Department of Internal Medicine and Paediatrics, Ghent University, Ghent, Belgium
| | - Rudy Van Coster
- Faculty of Medicine and Health Sciences, Department of Internal Medicine and Paediatrics, Ghent University, Ghent, Belgium
| | - Herbert Roeyers
- Faculty of Psychology and Educational Sciences, Department of Experimental Clinical and Health Psychology, Research in Developmental Disorders Lab, Ghent University, Ghent, Belgium
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3
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Ortiz-González XR. Mitochondrial Dysfunction: A Common Denominator in Neurodevelopmental Disorders? Dev Neurosci 2021; 43:222-229. [PMID: 34350863 PMCID: PMC8440386 DOI: 10.1159/000517870] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Accepted: 06/12/2021] [Indexed: 11/19/2022] Open
Abstract
Mitochondria, the organelles classically seen as the powerhouse of the cell, are increasingly associated with a wide variety of neurodevelopmental disorders. Although individually rare, a myriad of pediatric neurogenetic disorders have been identified in the last few years, thanks to advances in clinical genetic sequencing and data analysis. As this exponential growth continues, mitochondrial dysfunction is increasingly implicated in childhood neurodevelopmental disorders, with clinical presentations ranging from syndromic autism, intellectual disability, and epileptic encephalopathies to childhood onset neurodegeneration. Here we review recent evidence demonstrating mitochondrial involvement in neurodevelopmental disorders, identify emerging mechanistic trends, and reconsider the long-standing question of the role of mitochondria in light of new evidence: causation versus mere association.
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Affiliation(s)
- Xilma R Ortiz-González
- Division of Neurology, Department of Pediatrics, The Children's Hospital of Philadelphia and Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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4
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Mahalaxmi I, Subramaniam MD, Gopalakrishnan AV, Vellingiri B. Dysfunction in Mitochondrial Electron Transport Chain Complex I, Pyruvate Dehydrogenase Activity, and Mutations in ND1 and ND4 Gene in Autism Spectrum Disorder Subjects from Tamil Nadu Population, India. Mol Neurobiol 2021; 58:5303-5311. [PMID: 34279772 DOI: 10.1007/s12035-021-02492-w] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Accepted: 07/11/2021] [Indexed: 12/15/2022]
Abstract
Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterised by impaired social interaction and behavioural abnormalities. Growing evidence proved that impairment in mitochondrial functions could inhibit energy production and may contribute to the onset of ASD. Genetic variants in the genes of mitochondrial DNA (mtDNA) could interrupt the normal energy metabolism and production in the brain which lead to a wide range of structural and functional changes in the brain resulting in ASD. The present study aims to compare the activities of mitochondrial electron transport chain (ETC) complex I, pyruvate dehydrogenase (PDH) and specific mitochondrial DNA gene (MT-ND1 and MT-ND4) variants associated with ASD subjects in the Tamil Nadu population. Mutational analysis revealed that most mutations in ASD subjects showed synonymous type followed by missense in both the ND1 and ND4 genes. Interestingly, we found that the complex I and PDH dysfunctions may have a role in ASD compared to the controls (p ≤ 0.0001). Hence, the results of the present study suggest that mitochondrial dysfunction, specifically the complex I genes, may play a major role in the onset of ASD, concluding that further research on mitochondrial genes are mandatory to unravel the mechanism behind ASD pathogenesis.
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Affiliation(s)
- Iyer Mahalaxmi
- Livestock Farming and Bioresource Technology, Tamil Nadu, India
| | - Mohana Devi Subramaniam
- SN ONGC, Department of Genetics and Molecular Biology, Vision Research Foundation, Chennai, 600-006, India
| | - Abilash Valsala Gopalakrishnan
- Department of Biomedical Sciences, School of Biosciences and Technology, Vellore Institute of Technology, Tamil Nadu, Vellore, 632 014, India
| | - Balachandar Vellingiri
- Human Molecular Cytogenetics and Stem Cell Laboratory, Department of Human Genetics and Molecular Biology, Bharathiar University, Coimbatore, 641-046, Tamil Nadu, India.
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5
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Frye RE, Cakir J, Rose S, Palmer RF, Austin C, Curtin P, Arora M. Mitochondria May Mediate Prenatal Environmental Influences in Autism Spectrum Disorder. J Pers Med 2021; 11:218. [PMID: 33803789 PMCID: PMC8003154 DOI: 10.3390/jpm11030218] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 03/17/2021] [Accepted: 03/17/2021] [Indexed: 12/13/2022] Open
Abstract
We propose that the mitochondrion, an essential cellular organelle, mediates the long-term prenatal environmental effects of disease in autism spectrum disorder (ASD). Many prenatal environmental factors which increase the risk of developing ASD influence mitochondria physiology, including toxicant exposures, immune activation, and nutritional factors. Unique types of mitochondrial dysfunction have been associated with ASD and recent studies have linked prenatal environmental exposures to long-term changes in mitochondrial physiology in children with ASD. A better understanding of the role of the mitochondria in the etiology of ASD can lead to targeted therapeutics and strategies to potentially prevent the development of ASD.
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Affiliation(s)
- Richard E. Frye
- Barrow Neurological Institute at Phoenix Children’s Hospital, Phoenix, AZ 85016, USA
| | - Janet Cakir
- Department of Applied Ecology, North Carolina State University, Raleigh, NC 27695, USA;
| | - Shannon Rose
- Department of Pediatrics, Arkansas Children’s Research Institute, University of Arkansas for Medical Sciences, Little Rock, AR 72202, USA;
| | - Raymond F. Palmer
- Department of Family and Community Medicine, University of Texas Health Science Center, San Antonio, TX 78229, USA;
| | - Christine Austin
- Department of Environmental Medicine and Public Health, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA; (C.A.); (P.C.); (M.A.)
| | - Paul Curtin
- Department of Environmental Medicine and Public Health, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA; (C.A.); (P.C.); (M.A.)
| | - Manish Arora
- Department of Environmental Medicine and Public Health, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA; (C.A.); (P.C.); (M.A.)
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6
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Abnormalities of synaptic mitochondria in autism spectrum disorder and related neurodevelopmental disorders. J Mol Med (Berl) 2020; 99:161-178. [PMID: 33340060 PMCID: PMC7819932 DOI: 10.1007/s00109-020-02018-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Revised: 11/27/2020] [Accepted: 12/02/2020] [Indexed: 12/18/2022]
Abstract
Autism spectrum disorder (ASD) is a neurodevelopmental condition primarily characterized by an impairment of social interaction combined with the occurrence of repetitive behaviors. ASD starts in childhood and prevails across the lifespan. The variability of its clinical presentation renders early diagnosis difficult. Mutations in synaptic genes and alterations of mitochondrial functions are considered important underlying pathogenic factors, but it is obvious that we are far from a comprehensive understanding of ASD pathophysiology. At the synapse, mitochondria perform diverse functions, which are clearly not limited to their classical role as energy providers. Here, we review the current knowledge about mitochondria at the synapse and summarize the mitochondrial disturbances found in mouse models of ASD and other ASD-related neurodevelopmental disorders, like DiGeorge syndrome, Rett syndrome, Tuberous sclerosis complex, and Down syndrome.
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7
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Frye RE. Mitochondrial Dysfunction in Autism Spectrum Disorder: Unique Abnormalities and Targeted Treatments. Semin Pediatr Neurol 2020; 35:100829. [PMID: 32892956 DOI: 10.1016/j.spen.2020.100829] [Citation(s) in RCA: 54] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Several lines of evidence implicate mitochondria in the pathophysiology of autism spectrum disorder (ASD). In this review, we outline some of the evidence supporting this notion, as well as discuss novel abnormalities in mitochondrial function that appear to be related to ASD, and treatments that both target mitochondria and have evidence of usefulness in the treatment of ASD in clinical trials. A suspicion of the mitochondrion's involvement in ASD can be traced back to 1985 when lactic acidosis was noted in a subset of children with ASD. A large population-based study in 2007 confirmed this notion and found that a subset of children with ASD (∼4%) could be diagnosed with a definite mitochondrial disease. Further studies suggested that children with ASD and mitochondrial disease may have certain characteristics such as fatigability, gastrointestinal disorders, unusual types of neurodevelopmental regression, seizures/epilepsy, and motor delay. Further research examining biomarkers of mitochondrial dysfunction and electron transport chain activity suggest that abnormalities of mitochondrial function could affect a much higher number of children with ASD, perhaps up to 80%. Recent research has identified a type of dysfunction of mitochondria in which the activity of the electron transport chain is significantly increased. This novel type of mitochondrial dysfunction may be associated with environmental exposures and neurodevelopmental regression. Several treatments that target mitochondria appear to have evidence for use in children with ASD, including cofactors such as L-Carnitine and the ketogenic diet. Although the understanding of the involvement of mitochondria in ASD is evolving, the mitochondrion is clearly a novel molecular target which can be helpful in understanding the etiology of ASD and treatments that may improve function of children with ASD.
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Affiliation(s)
- Richard E Frye
- Division of Neurology, Section on Neurodevelopmental Disorders, Barrow Neurological Institute at Phoenix Children's Hospital, Phoenix, AZ; Department of Child Health, University of Arizona College of Medicine - Phoenix, Phoenix, AZ.
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8
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Parikh S, Karaa A, Goldstein A, Bertini ES, Chinnery PF, Christodoulou J, Cohen BH, Davis RL, Falk MJ, Fratter C, Horvath R, Koenig MK, Mancuso M, McCormack S, McCormick EM, McFarland R, Nesbitt V, Schiff M, Steele H, Stockler S, Sue C, Tarnopolsky M, Thorburn DR, Vockley J, Rahman S. Diagnosis of 'possible' mitochondrial disease: an existential crisis. J Med Genet 2019; 56:123-130. [PMID: 30683676 DOI: 10.1136/jmedgenet-2018-105800] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Revised: 12/11/2018] [Accepted: 12/23/2018] [Indexed: 02/02/2023]
Abstract
Primary genetic mitochondrial diseases are often difficult to diagnose, and the term 'possible' mitochondrial disease is used frequently by clinicians when such a diagnosis is suspected. There are now many known phenocopies of mitochondrial disease. Advances in genomic testing have shown that some patients with a clinical phenotype and biochemical abnormalities suggesting mitochondrial disease may have other genetic disorders. In instances when a genetic diagnosis cannot be confirmed, a diagnosis of 'possible' mitochondrial disease may result in harm to patients and their families, creating anxiety, delaying appropriate diagnosis and leading to inappropriate management or care. A categorisation of 'diagnosis uncertain', together with a specific description of the metabolic or genetic abnormalities identified, is preferred when a mitochondrial disease cannot be genetically confirmed.
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Affiliation(s)
- Sumit Parikh
- Mitochondrial Medicine Center, Neurologic Institute, Cleveland Clinic, Cleveland, Ohio, USA
| | - Amel Karaa
- Genetics Unit, Mitochondrial Disease Program, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Amy Goldstein
- Mitochondrial Medicine Frontier Program, Division of Human Genetics, Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA.,University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
| | - Enrico Silvio Bertini
- Unit of Neuromuscular and Neurodegenerative Disorders, Bambino Gesu Children's Hospital, IRCCS, Rome, Italy
| | - Patrick F Chinnery
- MRC Mitochondrial Biology Unit and Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - John Christodoulou
- Neurodevelopmental Genomics Research Group, Murdoch Children's Research Institute, Melbourne, Victoria, Australia.,Department of Paediatrics, Melbourne Medical School, University of Melbourne, Melbourne, Victoria, Australia
| | - Bruce H Cohen
- Department of Pediatrics and Rebecca D. Considine Research Institute, Akron Children's Hospital, Akron, Ohio, USA.,Northeast Ohio Medical University, Rootstown, Ohio, USA
| | - Ryan L Davis
- Northern Clinical School, University of Sydney, Sydney, New South Wales, Australia.,Department of Neurogenetics, Koling Institute, University of Sydney and Royal North Shore Hospital, Sydney, New South Wales, Australia
| | - Marni J Falk
- Mitochondrial Medicine Frontier Program, Division of Human Genetics, Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA.,University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
| | - Carl Fratter
- NHS Specialized Services for Rare Mitochondrial Disorders of Adults and Children UK, Oxford, UK.,Oxford Medical Genetics Laboratories, Oxford University, Oxford, UK
| | - Rita Horvath
- Wellcome Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK.,Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - Mary Kay Koenig
- Department of Pediatrics, Mitochondrial Center, University of Texas McGovern Medical School, Houston, Texas, USA
| | - Michaelangelo Mancuso
- Department of Experimental and Clinical Medicine, Neurological Institute, University of Pisa, Pisa, Italy
| | - Shana McCormack
- Mitochondrial Medicine Frontier Program, Division of Human Genetics, Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA.,University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
| | - Elizabeth M McCormick
- Mitochondrial Medicine Frontier Program, Division of Human Genetics, Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Robert McFarland
- Institute of Neurosciences, Wellcome Trust Centre for Mitochondrial Research, Newcastle University, Newcastle, UK
| | - Victoria Nesbitt
- Institute of Neurosciences, Wellcome Trust Centre for Mitochondrial Research, Newcastle University, Newcastle, UK.,NHS Highly Specialised Services for Rare Mitochondrial Disorders, Oxford University Hospitals, Oxford, UK
| | - Manuel Schiff
- Reference Center for Inborn Errors of Metabolism, Robert-Debré University Hospital, APHP, UMR1141, PROTECT, INSERM, Université Paris-Diderot, Paris, France
| | - Hannah Steele
- Wellcome Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK.,Department of Neurology, Sunderland Royal Hospital, Sunderland, UK
| | - Silvia Stockler
- Department of Pediatrics, Division of Biochemical Diseases, University of British Columbia, Vancouver, Canada
| | - Carolyn Sue
- Northern Clinical School, University of Sydney, Sydney, New South Wales, Australia.,Department of Neurogenetics, Koling Institute, University of Sydney and Royal North Shore Hospital, Sydney, New South Wales, Australia.,Department of Neurology, Royal North Shore Hospital, Sydney, NewSouth Wales, Australia
| | - Mark Tarnopolsky
- Department of Pediatrics, Neuromuscular and Neurometabolic Clinic, McMaster University, Hamilton, Ontario, Canada
| | - David R Thorburn
- Royal Children's Hospital, Murdoch Childrens Research Institute, Melbourne, Victoria, Australia.,Victorian Clinical Genetics Services, Royal Children's Hospital, Melbourne, Victoria, Australia.,Department of Paediatrics, University of Melbourne, Melbourne, Victoria, Australia
| | - Jerry Vockley
- Department of Pediatrics, University of Pittsburgh School of Medicine; Center for Rare Disease Therapy, Children's Hospital of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Shamima Rahman
- Mitochondrial Research Group, UCL Great Ormond Street Institute of Child Health, London, UK.,Metabolic Unit, Great Ormond Street Hospital NHS Foundation Trust, London, UK
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9
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Bennuri SC, Rose S, Frye RE. Mitochondrial Dysfunction Is Inducible in Lymphoblastoid Cell Lines From Children With Autism and May Involve the TORC1 Pathway. Front Psychiatry 2019; 10:269. [PMID: 31133888 PMCID: PMC6514096 DOI: 10.3389/fpsyt.2019.00269] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 04/09/2019] [Indexed: 01/25/2023] Open
Abstract
We previously developed a lymphoblastoid cell line (LCL) model of mitochondrial dysfunction in autism spectrum disorder (ASD); some individuals with ASD showed mitochondrial dysfunction (AD-A) while other individuals (AD-N) demonstrated mitochondrial respiration similar to controls (CNT). To test the hypothesis that mitochondrial dysfunction could be a consequence of environmental exposures through chronic elevations in reactive oxygen species (ROS), we exposed LCLs to prolonged ROS. We also examined expression of metabolic regulatory genes and the modulating effect of the mechanistic target of rapamycin (mTOR) pathway. Prolonged ROS exposure induced or worsened mitochondrial dysfunction in all LCL groups. Expression of genes associated with ROS protection was elevated in both AD-N and AD-A LCLs, but mitochondrial fission/fusion and mitoplasticity gene expression was only increased in AD-N LCLs. Partial least squares discriminant analysis showed that mTOR, UCP2 (uncoupling protein 2), SIRT1 (sirtuin 1), and MFN2 (mitofusin-2) gene expression differentiated LCL groups. Low-dose rapamycin (0.1 nM) normalized respiration with the magnitude of this normalization greater for AD-A LCLs, suggesting that the mammalian target of rapamycin complex 1 (mTORC1) pathway may have a different dynamic range for regulating mitochondrial activity in individuals with ASD with and without mitochondrial dysfunction, potentially related to S6K1 (S6 kinase beta-1) regulation. Understanding pathways that underlie mitochondrial dysfunction in ASD may lead to novel treatments.
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Affiliation(s)
- Sirish C Bennuri
- Arkansas Children's Research Institute and Department of Pediatrics, University of Arkansas for Medical Sciences, Little Rock, AR, United States
| | - Shannon Rose
- Arkansas Children's Research Institute and Department of Pediatrics, University of Arkansas for Medical Sciences, Little Rock, AR, United States
| | - Richard E Frye
- Barrow Neurologic Institute at Phoenix Children's Hospital, Phoenix, AZ, United States.,Department of Child Health, University of Arizona College of Medicine-Phoenix, Phoenix, AZ, United States
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10
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Wong S, Giulivi C. Autism, Mitochondria and Polybrominated Diphenyl Ether Exposure. CNS & NEUROLOGICAL DISORDERS-DRUG TARGETS 2017; 15:614-23. [PMID: 27071785 DOI: 10.2174/1871527315666160413122624] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Revised: 12/29/2015] [Accepted: 01/09/2016] [Indexed: 12/11/2022]
Abstract
BACKGROUND Autism spectrum disorders (ASD) are a growing concern with more than 1 in every 68 children affected in the United States by age 8. Limited scientific advances have been made regarding the etiology of autism, with general agreement that both genetic and environmental factors contribute to this disorder. OBJECTIVE To explore the link between exposure to PBDE, mitochondrial dysfunction and autism risk. RESULTS Perinatal exposures to PBDEs may contribute to the etiology or morbidity of ASD including mitochondrial dysfunction based on (i) their increased environmental abundance and human exposures, (ii) their activity towards implicated in neuronal development and synaptic plasticity including mitochondria, and (iii) their bioaccumulation in mitochondria. CONCLUSION In this review, we propose that PBDE, and possibly other environmental exposures, during child development can induce or compound mitochondrial dysfunction, which in conjunction with a dysregulated antioxidant response, increase a child's susceptibility of autism.
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Affiliation(s)
| | - Cecilia Giulivi
- University of California, Department of Molecular Biosciences, 1089 Veterinary Medicine Dr., 3009 VetMed3B, Davis, CA 95616, USA.
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11
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Burger BJ, Rose S, Bennuri SC, Gill PS, Tippett ML, Delhey L, Melnyk S, Frye RE. Autistic Siblings with Novel Mutations in Two Different Genes: Insight for Genetic Workups of Autistic Siblings and Connection to Mitochondrial Dysfunction. Front Pediatr 2017; 5:219. [PMID: 29075622 PMCID: PMC5643424 DOI: 10.3389/fped.2017.00219] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Accepted: 09/27/2017] [Indexed: 12/12/2022] Open
Abstract
The prevalence of autism spectrum disorder (ASD) is high, yet the etiology of this disorder is still uncertain. Advancements in genetic analysis have provided the ability to identify potential genetic changes that may contribute to ASD. Interestingly, several genetic syndromes have been linked to metabolic dysfunction, suggesting an avenue for treatment. In this case study, we report siblings with ASD who had similar initial phenotypic presentations. Whole exome sequencing (WES) revealed a novel c.795delT mutation in the WDR45 gene affecting the girl, which was consistent with her eventual progression to a Rett-like syndrome phenotype including seizures along with a stereotypical cyclic breathing pattern. Interestingly, WES identified that the brother harbored a novel heterozygous Y1546H variant in the DEP domain-containing protein 5 (DEPDC5) gene, consistent with his presentation. Both siblings underwent a metabolic workup that demonstrated different patterns of mitochondrial dysfunction. The girl demonstrated statistically significant elevations in mitochondrial activity of complex I + III in both muscle and fibroblasts and increased respiration in peripheral blood mononuclear cells (PBMCs) on Seahorse Extracellular Flux analysis. The boy demonstrates a statistically significant decrease in complex IV activity in buccal epithelium and decreased respiration in PBMCs. These cases highlight the differences in genetic abnormalities even in siblings with ASD phenotypes as well as highlights the individual role of novel mutations in the WDR45 and DEPDC5 genes. These cases demonstrate the importance of advanced genetic testing combined with metabolic evaluations in the workup of children with ASD.
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Affiliation(s)
- Barrett J Burger
- University of Arkansas for Medical Sciences, Little Rock, AR, United States
| | - Shannon Rose
- University of Arkansas for Medical Sciences, Little Rock, AR, United States.,Autism Research Program, Arkansas Children's Research Institute, Little Rock, AR, United States
| | - Sirish C Bennuri
- University of Arkansas for Medical Sciences, Little Rock, AR, United States.,Autism Research Program, Arkansas Children's Research Institute, Little Rock, AR, United States
| | | | - Marie L Tippett
- University of Arkansas for Medical Sciences, Little Rock, AR, United States.,Autism Research Program, Arkansas Children's Research Institute, Little Rock, AR, United States
| | - Leanna Delhey
- University of Arkansas for Medical Sciences, Little Rock, AR, United States.,Autism Research Program, Arkansas Children's Research Institute, Little Rock, AR, United States
| | - Stepan Melnyk
- University of Arkansas for Medical Sciences, Little Rock, AR, United States.,Autism Research Program, Arkansas Children's Research Institute, Little Rock, AR, United States
| | - Richard E Frye
- University of Arkansas for Medical Sciences, Little Rock, AR, United States.,Autism Research Program, Arkansas Children's Research Institute, Little Rock, AR, United States
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12
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Frye RE, Rossignol DA. Identification and Treatment of Pathophysiological Comorbidities of Autism Spectrum Disorder to Achieve Optimal Outcomes. CLINICAL MEDICINE INSIGHTS-PEDIATRICS 2016; 10:43-56. [PMID: 27330338 PMCID: PMC4910649 DOI: 10.4137/cmped.s38337] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Revised: 05/15/2016] [Accepted: 05/18/2016] [Indexed: 02/06/2023]
Abstract
Despite the fact that the prevalence of autism spectrum disorder (ASD) continues to rise, no effective medical treatments have become standard of care. In this paper we review some of the pathophysiological abnormalities associated with ASD and their potential associated treatments. Overall, there is evidence for some children with ASD being affected by seizure and epilepsy, neurotransmitter dysfunction, sleep disorders, metabolic abnormalities, including abnormalities in folate, cobalamin, tetrahydrobiopterin, carnitine, redox and mitochondrial metabolism, and immune and gastrointestinal disorders. Although evidence for an association between these pathophysiological abnormalities and ASD exists, the exact relationship to the etiology of ASD and its associated symptoms remains to be further defined in many cases. Despite these limitations, treatments targeting some of these pathophysiological abnormalities have been studied in some cases with high-quality studies, whereas treatments for other pathophysiological abnormalities have not been well studied in many cases. There are some areas of more promising treatments specific for ASD including neurotransmitter abnormalities, particularly imbalances in glutamate and acetylcholine, sleep onset disorder (with behavioral therapy and melatonin), and metabolic abnormalities in folate, cobalamin, tetrahydrobiopterin, carnitine, and redox pathways. There is some evidence for treatments of epilepsy and seizures, mitochondrial and immune disorders, and gastrointestinal abnormalities, particularly imbalances in the enteric microbiome, but further clinical studies are needed in these areas to better define treatments specific to children with ASD. Clearly, there are some promising areas of ASD research that could lead to novel treatments that could become standard of care in the future, but more research is needed to better define subgroups of children with ASD who are affected by specific pathophysiological abnormalities and the optimal treatments for these abnormalities.
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Affiliation(s)
- Richard E Frye
- Arkansas Children's Research Institute, Little Rock, AR, USA.; Division of Neurology, Department of Pediatrics, University of Arkansas for Medical Sciences, Little Rock, AR, USA
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Niyazov DM, Kahler SG, Frye RE. Primary Mitochondrial Disease and Secondary Mitochondrial Dysfunction: Importance of Distinction for Diagnosis and Treatment. Mol Syndromol 2016; 7:122-37. [PMID: 27587988 DOI: 10.1159/000446586] [Citation(s) in RCA: 145] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/11/2016] [Indexed: 12/28/2022] Open
Abstract
Mitochondrial disease refers to a heterogeneous group of disorders resulting in defective cellular energy production due to abnormal oxidative phosphorylation (oxphos). Primary mitochondrial disease (PMD) is diagnosed clinically and ideally, but not always, confirmed by a known or indisputably pathogenic mitochondrial DNA (mtDNA) or nuclear DNA (nDNA) mutation. The PMD genes either encode oxphos proteins directly or they affect oxphos function by impacting production of the complex machinery needed to run the oxphos process. However, many disorders have the 'mitochondrial' phenotype without an identifiable mtDNA or nDNA mutation or they have a variant of unknown clinical significance. Secondary mitochondrial dysfunction (SMD) can be caused by genes encoding neither function nor production of the oxphos proteins and accompanies many hereditary non-mitochondrial diseases. SMD may also be due to nongenetic causes such as environmental factors. In our practice, we see many patients with clinical signs of mitochondrial dysfunction based on phenotype, biomarkers, imaging, muscle biopsy, or negative/equivocal mtDNA or nDNA test results. In these cases, it is often tempting to assign a patient's phenotype to 'mitochondrial disease', but SMD is often challenging to distinguish from PMD. Fortunately, rapid advances in molecular testing, made possible by next generation sequencing, have been effective at least in some cases in establishing accurate diagnoses to distinguish between PMD and SMD. This is important, since their treatments and prognoses can be quite different. However, even in the absence of the ability to distinguish between PMD and SMD, treating SMD with standard treatments for PMD can be effective. We review the latest findings regarding mitochondrial disease/dysfunction and give representative examples in which differentiation between PMD and SMD has been crucial for diagnosis and treatment.
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Affiliation(s)
- Dmitriy M Niyazov
- Department of Pediatrics, Ochsner Clinic Foundation, New Orleans, La, USA
| | - Stephan G Kahler
- Department of Pediatrics, Arkansas Children's Hospital and Arkansas Children's Research Institute, University of Arkansas for Medical Sciences, Little Rock, Ark., USA
| | - Richard E Frye
- Department of Pediatrics, Arkansas Children's Hospital and Arkansas Children's Research Institute, University of Arkansas for Medical Sciences, Little Rock, Ark., USA
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Frye RE. Metabolic and mitochondrial disorders associated with epilepsy in children with autism spectrum disorder. Epilepsy Behav 2015; 47:147-57. [PMID: 25440829 DOI: 10.1016/j.yebeh.2014.08.134] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Revised: 08/25/2014] [Accepted: 08/27/2014] [Indexed: 01/07/2023]
Abstract
Autism spectrum disorder (ASD) affects a significant number of individuals in the United States, with the prevalence continuing to grow. A significant proportion of individuals with ASD have comorbid medical conditions such as epilepsy. In fact, treatment-resistant epilepsy appears to have a higher prevalence in children with ASD than in children without ASD, suggesting that current antiepileptic treatments may be suboptimal in controlling seizures in many individuals with ASD. Many individuals with ASD also appear to have underlying metabolic conditions. Metabolic conditions such as mitochondrial disease and dysfunction and abnormalities in cerebral folate metabolism may affect a substantial number of children with ASD, while other metabolic conditions that have been associated with ASD such as disorders of creatine, cholesterol, pyridoxine, biotin, carnitine, γ-aminobutyric acid, purine, pyrimidine, and amino acid metabolism and urea cycle disorders have also been associated with ASD without the prevalence clearly known. Interestingly, all of these metabolic conditions have been associated with epilepsy in children with ASD. The identification and treatment of these disorders could improve the underlying metabolic derangements and potentially improve behavior and seizure frequency and/or severity in these individuals. This paper provides an overview of these metabolic disorders in the context of ASD and discusses their characteristics, diagnostic testing, and treatment with concentration on mitochondrial disorders. To this end, this paper aims to help optimize the diagnosis and treatment of children with ASD and epilepsy. This article is part of a Special Issue entitled "Autism and Epilepsy".
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Affiliation(s)
- Richard E Frye
- Autism Research Program, Arkansas Children's Hospital Research Institute, Little Rock, AR, USA; Department of Pediatrics, University of Arkansas for Medical Sciences, Little Rock, AR, USA.
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Frye RE, Rose S, Slattery J, MacFabe DF. Gastrointestinal dysfunction in autism spectrum disorder: the role of the mitochondria and the enteric microbiome. MICROBIAL ECOLOGY IN HEALTH AND DISEASE 2015; 26:27458. [PMID: 25956238 PMCID: PMC4425813 DOI: 10.3402/mehd.v26.27458] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/01/2015] [Revised: 04/09/2015] [Accepted: 04/10/2015] [Indexed: 12/26/2022]
Abstract
Autism spectrum disorder (ASD) affects a significant number of individuals worldwide with the prevalence continuing to grow. It is becoming clear that a large subgroup of individuals with ASD demonstrate abnormalities in mitochondrial function as well as gastrointestinal (GI) symptoms. Interestingly, GI disturbances are common in individuals with mitochondrial disorders and have been reported to be highly prevalent in individuals with co-occurring ASD and mitochondrial disease. The majority of individuals with ASD and mitochondrial disorders do not manifest a primary genetic mutation, raising the possibility that their mitochondrial disorder is acquired or, at least, results from a combination of genetic susceptibility interacting with a wide range of environmental triggers. Mitochondria are very sensitive to both endogenous and exogenous environmental stressors such as toxicants, iatrogenic medications, immune activation, and metabolic disturbances. Many of these same environmental stressors have been associated with ASD, suggesting that the mitochondria could be the biological link between environmental stressors and neurometabolic abnormalities associated with ASD. This paper reviews the possible links between GI abnormalities, mitochondria, and ASD. First, we review the link between GI symptoms and abnormalities in mitochondrial function. Second, we review the evidence supporting the notion that environmental stressors linked to ASD can also adversely affect both mitochondria and GI function. Third, we review the evidence that enteric bacteria that are overrepresented in children with ASD, particularly Clostridia spp., produce short-chain fatty acid metabolites that are potentially toxic to the mitochondria. We provide an example of this gut–brain connection by highlighting the propionic acid rodent model of ASD and the clinical evidence that supports this animal model. Lastly, we discuss the potential therapeutic approaches that could be helpful for GI symptoms in ASD and mitochondrial disorders. To this end, this review aims to help better understand the underlying pathophysiology associated with ASD that may be related to concurrent mitochondrial and GI dysfunction.
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Affiliation(s)
- Richard E Frye
- Autism Research Program, Arkansas Children's Hospital Research Institute, Little Rock, AR, USA.,Department of Pediatrics, University of Arkansas for Medical Sciences, Little Rock, AR, USA;
| | - Shannon Rose
- Autism Research Program, Arkansas Children's Hospital Research Institute, Little Rock, AR, USA.,Department of Pediatrics, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - John Slattery
- Autism Research Program, Arkansas Children's Hospital Research Institute, Little Rock, AR, USA.,Department of Pediatrics, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Derrick F MacFabe
- Kilee Patchell-Evans Autism Research Group, Division of Developmental Disabilities, Departments of Psychology and Psychiatry, University of Western Ontario, London, ON, Canada
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Yiş U, Ezgü FS, Karakaya P, Polat İ, Arslan N, Çankaya T, Bozkaya ÖG, Kurul SH. A novel mutation in the mitochondrial DNA cytochrome b gene (MTCYB) in a patient with Prader Willi syndrome. J Child Neurol 2015; 30:378-81. [PMID: 24771578 DOI: 10.1177/0883073814530499] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
In recent years, it has been suggested that defects in energy metabolism may accompany Prader Willi syndrome. Mutations in the mitochondrial cytochrome b gene have been commonly associated isolated mitochondrial myopathy and exercise intolerance, rarely with multisystem disorders. The authors describe a novel mutation (mt. 15209T>C) in mitochondrial cytochrome b gene in a 2-year-old girl with Prader-Willi syndrome with a clinical history of lactic acidosis attacks, renal sodium loss, hepatopathy, progressive cerebral atrophy, and sudden death. The authors suggest that atypical clinical findings in patients with Prader-Willi syndrome should direct the physician to search for a mitochondrial disease.
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Affiliation(s)
- Uluç Yiş
- Department of Pediatrics, Division of Child Neurology, Dokuz Eylül University, School of Medicine, İzmir, Turkey
| | - Fatih Süheyl Ezgü
- Department of Pediatrics, Division of Pediatric Metabolism and Nutrition, Gazi University, School of Medicine, Ankara, Turkey
| | - Pakize Karakaya
- Department of Pediatrics, Division of Child Neurology, Dokuz Eylül University, School of Medicine, İzmir, Turkey
| | - İpek Polat
- Department of Pediatrics, Division of Child Neurology, Dokuz Eylül University, School of Medicine, İzmir, Turkey
| | - Nur Arslan
- Department of Pediatrics, Division of Pediatric Metabolism and Nutrition, Dokuz Eylül University, School of Medicine, Ankara, Turkey
| | - Tufan Çankaya
- Department of Pediatrics, Division of Genetics, Dokuz Eylül University, School of Medicine, Ankara, Turkey
| | - Özlem Giray Bozkaya
- Department of Pediatrics, Division of Genetics, Dokuz Eylül University, School of Medicine, Ankara, Turkey
| | - Semra Hız Kurul
- Department of Pediatrics, Division of Child Neurology, Dokuz Eylül University, School of Medicine, İzmir, Turkey
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Frye RE, Rossignol DA. Treatments for biomedical abnormalities associated with autism spectrum disorder. Front Pediatr 2014; 2:66. [PMID: 25019065 PMCID: PMC4073259 DOI: 10.3389/fped.2014.00066] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Accepted: 06/09/2014] [Indexed: 11/13/2022] Open
Abstract
Recent studies point to the effectiveness of novel treatments that address physiological abnormalities associated with autism spectrum disorder (ASD). This is significant because safe and effective treatments for ASD remain limited. These physiological abnormalities as well as studies addressing treatments of these abnormalities are reviewed in this article. Treatments commonly used to treat mitochondrial disease have been found to improve both core and associated ASD symptoms. Double-blind, placebo-controlled (DBPC) studies have investigated l-carnitine and a multivitamin containing B vitamins, antioxidants, vitamin E, and co-enzyme Q10 while non-blinded studies have investigated ubiquinol. Controlled and uncontrolled studies using folinic acid, a reduced form of folate, have reported marked improvements in core and associated ASD symptoms in some children with ASD and folate related pathway abnormities. Treatments that could address redox metabolism abnormalities include methylcobalamin with and without folinic acid in open-label studies and vitamin C and N-acetyl-l-cysteine in DBPC studies. These studies have reported improved core and associated ASD symptoms with these treatments. Lastly, both open-label and DBPC studies have reported improvements in core and associated ASD symptoms with tetrahydrobiopterin. Overall, these treatments were generally well-tolerated without significant adverse effects for most children, although we review the reported adverse effects in detail. This review provides evidence for potentially safe and effective treatments for core and associated symptoms of ASD that target underlying known physiological abnormalities associated with ASD. Further research is needed to define subgroups of children with ASD in which these treatments may be most effective as well as confirm their efficacy in DBPC, large-scale multicenter studies.
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Affiliation(s)
- Richard Eugene Frye
- Department of Pediatrics, Arkansas Children’s Hospital Research Institute, University of Arkansas for Medical Sciences, Little Rock, AR, USA
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Abstract
A comprehensive literature search was performed to collate evidence of mitochondrial dysfunction in autism spectrum disorders (ASDs) with two primary objectives. First, features of mitochondrial dysfunction in the general population of children with ASD were identified. Second, characteristics of mitochondrial dysfunction in children with ASD and concomitant mitochondrial disease (MD) were compared with published literature of two general populations: ASD children without MD, and non-ASD children with MD. The prevalence of MD in the general population of ASD was 5.0% (95% confidence interval 3.2, 6.9%), much higher than found in the general population (≈ 0.01%). The prevalence of abnormal biomarker values of mitochondrial dysfunction was high in ASD, much higher than the prevalence of MD. Variances and mean values of many mitochondrial biomarkers (lactate, pyruvate, carnitine and ubiquinone) were significantly different between ASD and controls. Some markers correlated with ASD severity. Neuroimaging, in vitro and post-mortem brain studies were consistent with an elevated prevalence of mitochondrial dysfunction in ASD. Taken together, these findings suggest children with ASD have a spectrum of mitochondrial dysfunction of differing severity. Eighteen publications representing a total of 112 children with ASD and MD (ASD/MD) were identified. The prevalence of developmental regression (52%), seizures (41%), motor delay (51%), gastrointestinal abnormalities (74%), female gender (39%), and elevated lactate (78%) and pyruvate (45%) was significantly higher in ASD/MD compared with the general ASD population. The prevalence of many of these abnormalities was similar to the general population of children with MD, suggesting that ASD/MD represents a distinct subgroup of children with MD. Most ASD/MD cases (79%) were not associated with genetic abnormalities, raising the possibility of secondary mitochondrial dysfunction. Treatment studies for ASD/MD were limited, although improvements were noted in some studies with carnitine, co-enzyme Q10 and B-vitamins. Many studies suffered from limitations, including small sample sizes, referral or publication biases, and variability in protocols for selecting children for MD workup, collecting mitochondrial biomarkers and defining MD. Overall, this evidence supports the notion that mitochondrial dysfunction is associated with ASD. Additional studies are needed to further define the role of mitochondrial dysfunction in ASD.
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Elahi M, Mahmood M, Shahbaz A, Malick N, Sajid J, Asopa S, Matata BM. Current concepts underlying benefits of exercise training in congestive heart failure patients. Curr Cardiol Rev 2011; 6:104-11. [PMID: 21532776 PMCID: PMC2892075 DOI: 10.2174/157340310791162640] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2009] [Revised: 01/09/2010] [Accepted: 02/01/2010] [Indexed: 01/14/2023] Open
Abstract
The pathophysiology of several conditions including heart failure is partly attributable to a failure of the cell energy metabolism. Studies have shown that exercise training (ET) improves quality of life (QOL) and is beneficial in terms of reduction of symptoms, mortality and duration of hospitalization. Increasingly, ET is now achieving acceptance as complimentary therapy in addition to routine clinical practice in patients with chronic heart failure (CHF). However, the mechanisms underlying the beneficial effects of ET are far less understood and need further evaluation. Evidence suggests that while CHF induces generalized metabolic energy depletion, ET largely enhances the overall function of the heart muscle. Hence, research efforts are now aiming to uncover why ET is beneficial as a complimentary treatment of CHF in the context of improving endothelial function and coronary perfusion, decreasing peripheral resistance, induction of cardiac and skeletal muscle cells remodeling, increasing oxygen uptake, substrate oxidation, and resistance to fatigue. Here we discuss the current evidence that suggest that there are beneficial effects of ET on cardiac and skeletal muscle cells oxidative metabolism and intracellular energy transfer in patients with CHF.
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Affiliation(s)
- Maqsood Elahi
- Wessex Cardiothoracic Centre, General/ BUPA, Chalybeate Close, Southampton, SO16 6UY, United Kingdom
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