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AMIRI S, SHEKARI KHANIANI M, MOHAMMADI A, ASADIAN M, MEHDIZADEH FANID L, SHAFIEE-KANDJANI AR. Molecular Evaluation of Ex3 VNTR Polymorphism of the DRD4 Gene in Patients With Autism Spectrum Disorder. IRANIAN JOURNAL OF CHILD NEUROLOGY 2022; 16:23-31. [PMID: 36478994 PMCID: PMC9699926 DOI: 10.22037/ijcn.v16i4.34289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Accepted: 09/26/2021] [Indexed: 01/03/2023]
Abstract
Objective Autism Spectrum Disorders (ASDs) are a group of neurodevelopmental disorders that affect social and communication skills. These diseases are characterized by severe communication and social skills disabilities and limited and repetitive activities. The prevalence of these disorders appears to be steadily increasing. It is proposed that the genes involved in the dopamine pathway may play an essential role in the development of autism. In this study, we investigated the possible association between Ex3 VNTR polymorphism of the DRD4 gene and autism spectrum disorders in the Iranian population. Materials & Methods In this case-control study, 97 children with autism and 103 healthy individuals from a northwestern area of Iran as the case and control groups, respectively. After genomic xtraction from peripheral blood samples by the proteinase K method, the polymerase chain reaction (PCR) technique was used to determine the polymorphism genotypes. The data were then coded and analyzed using SPSS version 22 software. Results The study results showed that the allele frequencies differed in the two groups, some of them being statistically significant. The most common allele in both the ASD and the control group was the 700 bp allele, and its frequency was significantly different in the two groups and was more common in the ASD group (p-value=0.0018). The other allele with a statistically different frequency was the 800 bp allele which was less frequent in the ASD group (p-value=0.0017). Conclusion These results suggest a potential association between Ex3 VNTR polymorphism of the DRD4 gene and autism spectrum disorder in the Iranian population. This necessitates further studies for the evaluation of the DRD4 gene.
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Affiliation(s)
- Shahrokh AMIRI
- Research Center of Psychiatry and Behavioral Sciences, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Mahmoud SHEKARI KHANIANI
- Department of Medical Genetics, Faculty of Medicine, Tabriz University of Medical Science, Tabriz, Iran
| | - Arman MOHAMMADI
- Research Center of Psychiatry and Behavioral Sciences, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Mahan ASADIAN
- Research Center of Psychiatry and Behavioral Sciences, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Leila MEHDIZADEH FANID
- Division of Cognitive Neuroscience, Department of Psychology, Faculty of Education and Psychology, Unive
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Ganesan H, Balasubramanian V, Iyer M, Venugopal A, Subramaniam MD, Cho SG, Vellingiri B. mTOR signalling pathway - A root cause for idiopathic autism? BMB Rep 2020. [PMID: 31186084 PMCID: PMC6675248 DOI: 10.5483/bmbrep.2019.52.7.137] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Autism spectrum disorder (ASD) is a complex neurodevelopmental monogenic disorder with a strong genetic influence. Idiopathic autism could be defined as a type of autism that does not have a specific causative agent. Among signalling cascades, mTOR signalling pathway plays a pivotal role not only in cell cycle, but also in protein synthesis and regulation of brain homeostasis in ASD patients. The present review highlights, underlying mechanism of mTOR and its role in altered signalling cascades as a triggering factor in the onset of idiopathic autism. Further, this review discusses how distorted mTOR signalling pathway stimulates truncated translation in neuronal cells and leads to downregulation of protein synthesis at dendritic spines of the brain. This review concludes by suggesting downstream regulators such as p70S6K, eIF4B, eIF4E of mTOR signalling pathway as promising therapeutic targets for idiopathic autistic individuals. [BMB Reports 2019; 52(7): 424-433].
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Affiliation(s)
- Harsha Ganesan
- Human Molecular Cytogenetics and Stem Cell Laboratory, Department of Human Genetics and Molecular Biology, Bharathiar University, Coimbatore 641046, Tamil Nadu, India
| | - Venkatesh Balasubramanian
- Human Molecular Cytogenetics and Stem Cell Laboratory, Department of Human Genetics and Molecular Biology, Bharathiar University, Coimbatore 641046, Tamil Nadu, India
| | - Mahalaxmi Iyer
- Department of Zoology, Avinashilingam Institute for Home Science and Higher Education for Women, Coimbatore 641043, Tamil Nadu, India
| | - Anila Venugopal
- Human Molecular Cytogenetics and Stem Cell Laboratory, Department of Human Genetics and Molecular Biology, Bharathiar University, Coimbatore 641046, Tamil Nadu, India
| | - Mohana Devi Subramaniam
- Department of Genetics and Molecular Biology, Vision Research Foundation, Sankara Nethralaya, Chennai 600006, Tamil Nadu, India
| | - Ssang-Goo Cho
- Department of Stem Cell and Regenerative Biotechnology, Konkuk University, Seoul 05029, Korea
| | - Balachandar Vellingiri
- Human Molecular Cytogenetics and Stem Cell Laboratory, Department of Human Genetics and Molecular Biology, Bharathiar University, Coimbatore 641046, Tamil Nadu, India
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Luo W, Zhang C, Jiang YH, Brouwer CR. Systematic reconstruction of autism biology from massive genetic mutation profiles. SCIENCE ADVANCES 2018; 4:e1701799. [PMID: 29651456 PMCID: PMC5895441 DOI: 10.1126/sciadv.1701799] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/29/2017] [Accepted: 02/22/2018] [Indexed: 06/08/2023]
Abstract
Autism spectrum disorder (ASD) affects 1% of world population and has become a pressing medical and social problem worldwide. As a paradigmatic complex genetic disease, ASD has been intensively studied and thousands of gene mutations have been reported. Because these mutations rarely recur, it is difficult to (i) pinpoint the fewer disease-causing versus majority random events and (ii) replicate or verify independent studies. A coherent and systematic understanding of autism biology has not been achieved. We analyzed 3392 and 4792 autism-related mutations from two large-scale whole-exome studies across multiple resolution levels, that is, variants (single-nucleotide), genes (protein-coding unit), and pathways (molecular module). These mutations do not recur or replicate at the variant level, but significantly and increasingly do so at gene and pathway levels. Genetic association reveals a novel gene + pathway dual-hit model, where the mutation burden becomes less relevant. In multiple independent analyses, hundreds of variants or genes repeatedly converge to several canonical pathways, either novel or literature-supported. These pathways define recurrent and systematic ASD biology, distinct from previously reported gene groups or networks. They also present a catalog of novel ASD risk factors including 118 variants and 72 genes. At a subpathway level, most variants disrupt the pathway-related gene functions, and in the same gene, they tend to hit residues extremely close to each other and in the same domain. Multiple interacting variants spotlight key modules, including the cAMP (adenosine 3',5'-monophosphate) second-messenger system and mGluR (metabotropic glutamate receptor) signaling regulation by GRKs (G protein-coupled receptor kinases). At a superpathway level, distinct pathways further interconnect and converge to three biology themes: synaptic function, morphology, and plasticity.
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Affiliation(s)
- Weijun Luo
- Department of Bioinformatics and Genomics, University of North Carolina (UNC) at Charlotte, Charlotte, NC 28223, USA
- UNC Charlotte Bioinformatics Service Division, North Carolina Research Campus, Kannapolis, NC 28081, USA
| | - Chaolin Zhang
- Department of Systems Biology, Department of Biochemistry and Molecular Biophysics, Center for Motor Neuron Biology and Disease, Columbia University, New York, NY 10032, USA
| | - Yong-hui Jiang
- Department of Pediatrics, Department of Neurobiology, Program in Genetics and Genomics, School of Medicine, Duke University, Durham, NC 27710, USA
| | - Cory R. Brouwer
- Department of Bioinformatics and Genomics, University of North Carolina (UNC) at Charlotte, Charlotte, NC 28223, USA
- UNC Charlotte Bioinformatics Service Division, North Carolina Research Campus, Kannapolis, NC 28081, USA
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Zhubi A, Chen Y, Guidotti A, Grayson DR. Epigenetic regulation of RELN and GAD1 in the frontal cortex (FC) of autism spectrum disorder (ASD) subjects. Int J Dev Neurosci 2017; 62:63-72. [PMID: 28229923 PMCID: PMC5575980 DOI: 10.1016/j.ijdevneu.2017.02.003] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2017] [Revised: 02/08/2017] [Accepted: 02/09/2017] [Indexed: 01/01/2023] Open
Abstract
Both Reelin (RELN) and glutamate decarboxylase 67 (GAD1) have been implicated in the pathophysiology of Autism Spectrum Disorders (ASD). We have previously shown that both mRNAs are reduced in the cerebella (CB) of ASD subjects through a mechanism that involves increases in the amounts of MECP2 binding to the corresponding promoters. In the current study, we examined the expression of RELN, GAD1, GAD2, and several other mRNAs implicated in this disorder in the frontal cortices (FC) of ASD and CON subjects. We also focused on the role that epigenetic processes play in the regulation of these genes in ASD brain. Our goal is to better understand the molecular basis for the down-regulation of genes expressed in GABAergic neurons in ASD brains. We measured mRNA levels corresponding to selected GABAergic genes using qRT-PCR in RNA isolated from both ASD and CON groups. We determined the extent of binding of MECP2 and DNMT1 repressor proteins by chromatin immunoprecipitation (ChIP) assays. The amount of 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC) present in the promoters of the target genes was quantified by methyl DNA immunoprecipitation (MeDIP) and hydroxyl MeDIP (hMeDIP). We detected significant reductions in the mRNAs associated with RELN and GAD1 and significant increases in mRNAs encoding the Ten-eleven Translocation (TET) enzymes 1, 2, and 3. We also detected increased MECP2 and DNMT1 binding to the corresponding promoter regions of GAD1, RELN, and GAD2. Interestingly, there were decreased amounts of 5mC at both promoters and little change in 5hmC content in these same DNA fragments. Our data demonstrate that RELN, GAD1, and several other genes selectively expressed in GABAergic neurons, are down-regulated in post-mortem ASD FC. In addition, we observed increased DNMT1 and MECP2 binding at the corresponding promoters of these genes. The finding of increased MECP2 binding to the RELN, GAD1 and GAD2 promoters, with reduced amounts of 5mC and unchanged amounts of 5hmC present in these regions, suggests the possibility that DNMT1 interacts with and alters MECP2 binding properties to selected promoters. Comparisons between data obtained from the FC with CB studies showed some common themes between brain regions which are discussed.
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Affiliation(s)
- Adrian Zhubi
- The Psychiatric Institute, Center for Alcohol Research in Epigenetics, Department of Psychiatry, College of Medicine, University of Illinois at Chicago, United States.
| | - Ying Chen
- The Psychiatric Institute, Center for Alcohol Research in Epigenetics, Department of Psychiatry, College of Medicine, University of Illinois at Chicago, United States.
| | - Alessandro Guidotti
- The Psychiatric Institute, Center for Alcohol Research in Epigenetics, Department of Psychiatry, College of Medicine, University of Illinois at Chicago, United States.
| | - Dennis R Grayson
- The Psychiatric Institute, Center for Alcohol Research in Epigenetics, Department of Psychiatry, College of Medicine, University of Illinois at Chicago, United States.
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Klein M, van Donkelaar M, Verhoef E, Franke B. Imaging genetics in neurodevelopmental psychopathology. Am J Med Genet B Neuropsychiatr Genet 2017; 174:485-537. [PMID: 29984470 PMCID: PMC7170264 DOI: 10.1002/ajmg.b.32542] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Revised: 02/02/2017] [Accepted: 03/10/2017] [Indexed: 01/27/2023]
Abstract
Neurodevelopmental disorders are defined by highly heritable problems during development and brain growth. Attention-deficit/hyperactivity disorder (ADHD), autism spectrum disorders (ASDs), and intellectual disability (ID) are frequent neurodevelopmental disorders, with common comorbidity among them. Imaging genetics studies on the role of disease-linked genetic variants on brain structure and function have been performed to unravel the etiology of these disorders. Here, we reviewed imaging genetics literature on these disorders attempting to understand the mechanisms of individual disorders and their clinical overlap. For ADHD and ASD, we selected replicated candidate genes implicated through common genetic variants. For ID, which is mainly caused by rare variants, we included genes for relatively frequent forms of ID occurring comorbid with ADHD or ASD. We reviewed case-control studies and studies of risk variants in healthy individuals. Imaging genetics studies for ADHD were retrieved for SLC6A3/DAT1, DRD2, DRD4, NOS1, and SLC6A4/5HTT. For ASD, studies on CNTNAP2, MET, OXTR, and SLC6A4/5HTT were found. For ID, we reviewed the genes FMR1, TSC1 and TSC2, NF1, and MECP2. Alterations in brain volume, activity, and connectivity were observed. Several findings were consistent across studies, implicating, for example, SLC6A4/5HTT in brain activation and functional connectivity related to emotion regulation. However, many studies had small sample sizes, and hypothesis-based, brain region-specific studies were common. Results from available studies confirm that imaging genetics can provide insight into the link between genes, disease-related behavior, and the brain. However, the field is still in its early stages, and conclusions about shared mechanisms cannot yet be drawn.
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Affiliation(s)
- Marieke Klein
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud university medical center, Nijmegen, The Netherlands
| | - Marjolein van Donkelaar
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud university medical center, Nijmegen, The Netherlands
| | - Ellen Verhoef
- Language and Genetics Department, Max Planck Institute for Psycholinguistics, Nijmegen, The Netherlands
| | - Barbara Franke
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud university medical center, Nijmegen, The Netherlands
- Department of Psychiatry, Donders Institute for Brain, Cognition and Behaviour, Radboud university medical center, Nijmegen, The Netherlands
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Ripamonti S, Ambrozkiewicz MC, Guzzi F, Gravati M, Biella G, Bormuth I, Hammer M, Tuffy LP, Sigler A, Kawabe H, Nishimori K, Toselli M, Brose N, Parenti M, Rhee J. Transient oxytocin signaling primes the development and function of excitatory hippocampal neurons. eLife 2017; 6. [PMID: 28231043 PMCID: PMC5323041 DOI: 10.7554/elife.22466] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Accepted: 02/06/2017] [Indexed: 12/30/2022] Open
Abstract
Beyond its role in parturition and lactation, oxytocin influences higher brain processes that control social behavior of mammals, and perturbed oxytocin signaling has been linked to the pathogenesis of several psychiatric disorders. However, it is still largely unknown how oxytocin exactly regulates neuronal function. We show that early, transient oxytocin exposure in vitro inhibits the development of hippocampal glutamatergic neurons, leading to reduced dendrite complexity, synapse density, and excitatory transmission, while sparing GABAergic neurons. Conversely, genetic elimination of oxytocin receptors increases the expression of protein components of excitatory synapses and excitatory synaptic transmission in vitro. In vivo, oxytocin-receptor-deficient hippocampal pyramidal neurons develop more complex dendrites, which leads to increased spine number and reduced γ-oscillations. These results indicate that oxytocin controls the development of hippocampal excitatory neurons and contributes to the maintenance of a physiological excitation/inhibition balance, whose disruption can cause neurobehavioral disturbances. DOI:http://dx.doi.org/10.7554/eLife.22466.001
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Affiliation(s)
- Silvia Ripamonti
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, Göttingen, Germany.,Department of Medicine and Surgery, University of Milan-Bicocca, Monza, Italy
| | - Mateusz C Ambrozkiewicz
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, Göttingen, Germany.,Cortical Development, Institute of Cell Biology and Neurobiology, Charité-Universitätsmedizin, Berlin, Germany
| | - Francesca Guzzi
- Department of Medicine and Surgery, University of Milan-Bicocca, Monza, Italy.,NeuroMi - Milan Center for Neuroscience, Monza, Italy
| | - Marta Gravati
- Department of Biology and Biotechnology, University of Pavia, Pavia, Italy
| | - Gerardo Biella
- Department of Biology and Biotechnology, University of Pavia, Pavia, Italy
| | - Ingo Bormuth
- Cortical Development, Institute of Cell Biology and Neurobiology, Charité-Universitätsmedizin, Berlin, Germany
| | - Matthieu Hammer
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, Göttingen, Germany
| | - Liam P Tuffy
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, Göttingen, Germany
| | - Albrecht Sigler
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, Göttingen, Germany
| | - Hiroshi Kawabe
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, Göttingen, Germany
| | - Katsuhiko Nishimori
- Department of Molecular and Cell Biology, Graduate School of Agricultural Science, Tohoku University, Miyagi, Japan
| | - Mauro Toselli
- Department of Biology and Biotechnology, University of Pavia, Pavia, Italy
| | - Nils Brose
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, Göttingen, Germany
| | - Marco Parenti
- Department of Medicine and Surgery, University of Milan-Bicocca, Monza, Italy.,NeuroMi - Milan Center for Neuroscience, Monza, Italy
| | - JeongSeop Rhee
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, Göttingen, Germany
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Zatkova M, Bakos J, Hodosy J, Ostatnikova D. Synapse alterations in autism: Review of animal model findings. Biomed Pap Med Fac Univ Palacky Olomouc Czech Repub 2016; 160:201-10. [DOI: 10.5507/bp.2015.066] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Accepted: 12/04/2015] [Indexed: 12/30/2022] Open
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Impairments in dendrite morphogenesis as etiology for neurodevelopmental disorders and implications for therapeutic treatments. Neurosci Biobehav Rev 2016; 68:946-978. [PMID: 27143622 DOI: 10.1016/j.neubiorev.2016.04.008] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2015] [Revised: 04/13/2016] [Accepted: 04/13/2016] [Indexed: 02/08/2023]
Abstract
Dendrite morphology is pivotal for neural circuitry functioning. While the causative relationship between small-scale dendrite morphological abnormalities (shape, density of dendritic spines) and neurodevelopmental disorders is well established, such relationship remains elusive for larger-scale dendrite morphological impairments (size, shape, branching pattern of dendritic trees). Here, we summarize published data on dendrite morphological irregularities in human patients and animal models for neurodevelopmental disorders, with focus on autism and schizophrenia. We next discuss high-risk genes for these disorders and their role in dendrite morphogenesis. We finally overview recent developments in therapeutic attempts and we discuss how they relate to dendrite morphology. We find that both autism and schizophrenia are accompanied by dendritic arbor morphological irregularities, and that majority of their high-risk genes regulate dendrite morphogenesis. Thus, we present a compelling argument that, along with smaller-scale morphological impairments in dendrites (spines and synapse), irregularities in larger-scale dendrite morphology (arbor shape, size) may be an important part of neurodevelopmental disorders' etiology. We suggest that this should not be ignored when developing future therapeutic treatments.
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9
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Hutton J. Does Rubella Cause Autism: A 2015 Reappraisal? Front Hum Neurosci 2016; 10:25. [PMID: 26869906 PMCID: PMC4734211 DOI: 10.3389/fnhum.2016.00025] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2015] [Accepted: 01/18/2016] [Indexed: 01/03/2023] Open
Abstract
In the 1970s, Stella Chess found a high prevalence of autism in children with congenital rubella syndrome (CRS), 200 times that of the general population at the time. Many researchers quote this fact to add proof to the current theory that maternal infection with immune system activation in pregnancy leads to autism in the offspring. This rubella and autism association is presented with the notion that rubella has been eliminated in today’s world. CRS cases are no longer typically seen; yet, autistic children often share findings of CRS including deafness, congenital heart defects, and to a lesser extent visual changes. Autistic children commonly have hyperactivity and spasticity, as do CRS children. Both autistic and CRS individuals may develop type 1 diabetes as young adults. Neuropathology of CRS infants may reveal cerebral vasculitis with narrowed lumens and cerebral necrosis. Neuroradiological findings of children with CRS show calcifications, periventricular leukomalacia, and dilated perivascular spaces. Neuroradiology of autism has also demonstrated hyperintensities, leukomalacia, and prominent perivascular spaces. PET studies of autistic individuals exhibit decreased perfusion to areas of the brain similarly affected by rubella. In both autism and CRS, certain changes in the brain have implicated the immune system. Several children with autism lack antibodies to rubella, as do children with CRS. These numerous similarities increase the probability of an association between rubella virus and autism. Rubella and autism cross many ethnicities in many countries. Contrary to current belief, rubella has not been eradicated and globally affects up to 5% of pregnant women. Susceptibility continues as vaccines are not given worldwide and are not fully protective. Rubella might still cause autism, even in vaccinated populations.
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Affiliation(s)
- Jill Hutton
- Department of Obstetrics and Gynecology, The Woman's Hospital of Texas , Houston, TX , USA
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Loth E, Murphy DG, Spooren W. Defining Precision Medicine Approaches to Autism Spectrum Disorders: Concepts and Challenges. Front Psychiatry 2016; 7:188. [PMID: 27965598 PMCID: PMC5126086 DOI: 10.3389/fpsyt.2016.00188] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Accepted: 11/09/2016] [Indexed: 12/24/2022] Open
Abstract
The tremendous clinical and etiological variability between individuals with autism spectrum disorder (ASD) has made precision medicine the most promising treatment approach. It aims to combine new pathophysiologically based treatments with objective tests (stratification biomarkers) to predict which treatment may be beneficial for a particular person. Here we discuss significant advances and current challenges for this approach: rare monogenic forms of ASD have provided a major breakthrough for the identification of treatment targets by providing a means to trace causal links from a gene to specific molecular alterations and biological pathways. To estimate whether treatment targets thus identified may be useful for larger patient groups we need a better understanding of whether different etiologies (i.e., genetic and environmental risk factors acting at different critical time points) lead to convergent or divergent molecular mechanisms, and how they map onto differences in circuit-level brain and cognitive development, and behavioral symptom profiles. Several recently failed clinical trials with syndromic forms of ASD provide valuable insights into conceptual and methodological issues linked to limitations in the translatability from animal models to humans, placebo effects, and a need for mechanistically plausible, objective outcome measures. To identify stratification biomarkers that enrich participant selection in clinical trials, large-scale multi-modal longitudinal observational studies are underway. Addressing these different factors in the next generation of research studies requires a translatable developmental perspective and multidisciplinary, collaborative efforts, with a commitment to sharing protocols and data, to increase transparency and reproducibility.
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Affiliation(s)
- Eva Loth
- Department of Forensic and Neurodevelopmental Sciences, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK; Sackler Institute for Translational Neurodevelopment, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | - Declan G Murphy
- Department of Forensic and Neurodevelopmental Sciences, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK; Sackler Institute for Translational Neurodevelopment, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | - Will Spooren
- Roche Pharmaceutical Research and Early Development, NORD Discovery and Translational Area, Roche Innovation Center , Basel , Switzerland
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Grayson DR, Guidotti A. Merging data from genetic and epigenetic approaches to better understand autistic spectrum disorder. Epigenomics 2015; 8:85-104. [PMID: 26551091 PMCID: PMC4864049 DOI: 10.2217/epi.15.92] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Autism spectrum disorder (ASD) is a complex neurodevelopmental disorder that is characterized by a wide range of cognitive and behavioral abnormalities. Genetic research has identified large numbers of genes that contribute to ASD phenotypes. There is compelling evidence that environmental factors contribute to ASD through influences that differentially impact the brain through epigenetic mechanisms. Both genetic mutations and epigenetic influences alter gene expression in different cell types of the brain. Mutations impact the expression of large numbers of genes and also have downstream consequences depending on specific pathways associated with the mutation. Environmental factors impact the expression of sets of genes by altering methylation/hydroxymethylation patterns, local histone modification patterns and chromatin remodeling. Herein, we discuss recent developments in the research of ASD with a focus on epigenetic pathways as a complement to current genetic screening.
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Affiliation(s)
- Dennis R Grayson
- Department of Psychiatry, The Psychiatric Institute, University of Illinois at Chicago, 1601 W. Taylor St., Chicago, IL 60607, USA
| | - Alessandro Guidotti
- Department of Psychiatry, The Psychiatric Institute, University of Illinois at Chicago, 1601 W. Taylor St., Chicago, IL 60607, USA
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12
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Ben-Ari Y. Is birth a critical period in the pathogenesis of autism spectrum disorders? Nat Rev Neurosci 2015; 16:498-505. [DOI: 10.1038/nrn3956] [Citation(s) in RCA: 81] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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13
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Bakos J, Bacova Z, Grant SG, Castejon AM, Ostatnikova D. Are Molecules Involved in Neuritogenesis and Axon Guidance Related to Autism Pathogenesis? Neuromolecular Med 2015; 17:297-304. [PMID: 25989848 DOI: 10.1007/s12017-015-8357-7] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Accepted: 05/08/2015] [Indexed: 12/27/2022]
Abstract
Autism spectrum disorder is a heterogeneous disease, and numerous alterations of gene expression come into play to attempt to explain potential molecular and pathophysiological causes. Abnormalities of brain development and connectivity associated with alterations in cytoskeletal rearrangement, neuritogenesis and elongation of axons and dendrites might represent or contribute to the structural basis of autism pathology. Slit/Robo signaling regulates cytoskeletal remodeling related to axonal and dendritic branching. Components of its signaling pathway (ABL and Cdc42) are suspected to be molecular bases of alterations of normal development. The present review describes the most important mechanisms underlying neuritogenesis, axon pathfinding and the role of GTPases in neurite outgrowth, with special emphasis on alterations associated with autism spectrum disorders. On the basis of analysis of publicly available microarray data, potential biomarkers of autism are discussed.
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Affiliation(s)
- Jan Bakos
- Institute of Experimental Endocrinology, Slovak Academy of Sciences, Vlarska 3, Bratislava, Slovakia,
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14
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Baron-Cohen S, Auyeung B, Nørgaard-Pedersen B, Hougaard DM, Abdallah MW, Melgaard L, Cohen AS, Chakrabarti B, Ruta L, Lombardo MV. Elevated fetal steroidogenic activity in autism. Mol Psychiatry 2015; 20:369-76. [PMID: 24888361 PMCID: PMC4184868 DOI: 10.1038/mp.2014.48] [Citation(s) in RCA: 308] [Impact Index Per Article: 34.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2013] [Revised: 03/25/2014] [Accepted: 03/27/2014] [Indexed: 12/16/2022]
Abstract
Autism affects males more than females, giving rise to the idea that the influence of steroid hormones on early fetal brain development may be one important early biological risk factor. Utilizing the Danish Historic Birth Cohort and Danish Psychiatric Central Register, we identified all amniotic fluid samples of males born between 1993 and 1999 who later received ICD-10 (International Classification of Diseases, 10th Revision) diagnoses of autism, Asperger syndrome or PDD-NOS (pervasive developmental disorder not otherwise specified) (n=128) compared with matched typically developing controls. Concentration levels of Δ4 sex steroids (progesterone, 17α-hydroxy-progesterone, androstenedione and testosterone) and cortisol were measured with liquid chromatography tandem mass spectrometry. All hormones were positively associated with each other and principal component analysis confirmed that one generalized latent steroidogenic factor was driving much of the variation in the data. The autism group showed elevations across all hormones on this latent generalized steroidogenic factor (Cohen's d=0.37, P=0.0009) and this elevation was uniform across ICD-10 diagnostic label. These results provide the first direct evidence of elevated fetal steroidogenic activity in autism. Such elevations may be important as epigenetic fetal programming mechanisms and may interact with other important pathophysiological factors in autism.
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Affiliation(s)
- S Baron-Cohen
- Autism Research Centre, Department of Psychiatry, University of Cambridge, Cambridge, UK,Autism Research Centre, Department of Psychiatry, University of Cambridge, Douglas House, 18B Trumpington Road, Cambridge CB2 8AH, UK. E-mail:
| | - B Auyeung
- Autism Research Centre, Department of Psychiatry, University of Cambridge, Cambridge, UK,Department of Psychology, University of Edinburgh, Edinburgh, UK
| | - B Nørgaard-Pedersen
- Department of Clinical Biochemistry and Immunology, Statens Serum Institute Copenhagen, Copenhagen, Denmark
| | - D M Hougaard
- Department of Clinical Biochemistry and Immunology, Statens Serum Institute Copenhagen, Copenhagen, Denmark
| | - M W Abdallah
- Department of Clinical Biochemistry and Immunology, Statens Serum Institute Copenhagen, Copenhagen, Denmark,Department of Child and Adolescent Neuropsychiatry, Rostock University Medical Centre, Rostock, Germany,Section for Epidemiology, Department of Public Health, Aarhus University, Aarhus, Denmark
| | - L Melgaard
- Department of Clinical Biochemistry and Immunology, Statens Serum Institute Copenhagen, Copenhagen, Denmark
| | - A S Cohen
- Department of Clinical Biochemistry and Immunology, Statens Serum Institute Copenhagen, Copenhagen, Denmark
| | - B Chakrabarti
- Autism Research Centre, Department of Psychiatry, University of Cambridge, Cambridge, UK,Centre for Integrative Neuroscience and Neurodynamics, School of Psychology and Clinical Language Sciences, University of Reading, Reading, UK
| | - L Ruta
- Autism Research Centre, Department of Psychiatry, University of Cambridge, Cambridge, UK,Division of Child Neurology and Psychiatry, Stella Maris Scientific Institute, Pisa, Italy
| | - M V Lombardo
- Autism Research Centre, Department of Psychiatry, University of Cambridge, Cambridge, UK,Department of Psychology, University of Cyprus, Nicosia, Cyprus,Centre for Applied Neuroscience, University of Cyprus, Nicosia, Cyprus
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15
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Main PA, Thomas P, Angley MT, Young R, Esterman A, King CE, Fenech MF. Lack of Evidence for Genomic Instability in Autistic Children as Measured by the Cytokinesis-Block Micronucleus Cytome Assay. Autism Res 2014; 8:94-104. [DOI: 10.1002/aur.1428] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2013] [Accepted: 09/26/2014] [Indexed: 01/19/2023]
Affiliation(s)
- Penelope A.E. Main
- Sansom Institute of Health Research; University of South Australia; Adelaide Australia
- Department of Animal, Food and Health Sciences; Commonwealth Scientific and Industrial Research Organisation; Adelaide Australia
| | - Philip Thomas
- Department of Animal, Food and Health Sciences; Commonwealth Scientific and Industrial Research Organisation; Adelaide Australia
| | - Manya T. Angley
- Sansom Institute of Health Research; University of South Australia; Adelaide Australia
| | - Robyn Young
- Finders University of South Australia; Adelaide Australia
| | - Adrian Esterman
- School of Nursing and Midwifery; University of South Australia; Adelaide Australia
- Centre for Research Excellence in Chronic Disease; James Cook University; Townsville Australia
| | - Catherine E. King
- Sansom Institute of Health Research; University of South Australia; Adelaide Australia
| | - Michael F. Fenech
- Department of Animal, Food and Health Sciences; Commonwealth Scientific and Industrial Research Organisation; Adelaide Australia
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16
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The GABA excitatory/inhibitory developmental sequence: a personal journey. Neuroscience 2014; 279:187-219. [PMID: 25168736 DOI: 10.1016/j.neuroscience.2014.08.001] [Citation(s) in RCA: 194] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Revised: 07/17/2014] [Accepted: 08/01/2014] [Indexed: 12/11/2022]
Abstract
The developing brain is talkative but its language is not that of the adult. Most if not all voltage and transmitter-gated ionic currents follow a developmental sequence and network-driven patterns differ in immature and adult brains. This is best illustrated in studies engaged almost three decades ago in which we observed elevated intracellular chloride (Cl(-))i levels and excitatory GABA early during development and a perinatal excitatory/inhibitory shift. This sequence is observed in a wide range of brain structures and animal species suggesting that it has been conserved throughout evolution. It is mediated primarily by a developmentally regulated expression of the NKCC1 and KCC2 chloride importer and exporter respectively. The GABAergic depolarization acts in synergy with N-methyl-d-aspartate (NMDA) receptor-mediated and voltage-gated calcium currents to enhance intracellular calcium exerting trophic effects on neuritic growth, migration and synapse formation. These sequences can be deviated in utero by genetic or environmental insults leading to a persistence of immature features in the adult brain. This "neuroarcheology" concept paves the way to novel therapeutic perspectives based on the use of drugs that block immature but not adult currents. This is illustrated notably with the return to immature high levels of chloride and excitatory actions of GABA observed in many pathological conditions. This is due to the fact that in the immature brain a down regulation of KCC2 and an up regulation of NKCC1 are seen. Here, I present a personal history of how an unexpected observation led to novel concepts in developmental neurobiology and putative treatments of autism and other developmental disorders. Being a personal account, this review is neither exhaustive nor provides an update of this topic with all the studies that have contributed to this evolution. We all rely on previous inventors to allow science to advance. Here, I present a personal summary of this topic primarily to illustrate why we often fail to comprehend the implications of our own observations. They remind us - and policy deciders - why Science cannot be programed, requiring time, and risky investigations that raise interesting questions before being translated from bench to bed. Discoveries are always on sideways, never on highways.
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17
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Casanova MF. Autism as a sequence: from heterochronic germinal cell divisions to abnormalities of cell migration and cortical dysplasias. Med Hypotheses 2014; 83:32-8. [PMID: 24780284 PMCID: PMC4070182 DOI: 10.1016/j.mehy.2014.04.014] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2014] [Revised: 03/11/2014] [Accepted: 04/06/2014] [Indexed: 02/07/2023]
Abstract
The considerable heterogeneity in the number and severity of symptoms observed in autism spectrum disorders (ASD) has been regarded as an obstacle to any future research. Some authors believe that clinical heterogeneity results from the complex interplay of the many genetic and environmental factors that themselves define a condition as multifactorial. However, it is important to note that neuropathological findings in both idiopathic and syndromic autism suggests a single pathophysiological mechanism acting during brain development: the heterochronic division of germinal cells and subsequent migrational abnormalities of daughter cells to their target fields. Multiple exogenous (e.g., viruses, drugs) and endogenous (e.g., genetic mutations) factors are known to disrupt the division of germinal cells and provide for an autism phenotype. The variety of endogenous and exogenous factors, their timing of action during brain development, and the genetic susceptibility of affected individuals (a Triple Hit hypothesis) may all account for the clinical heterogeneity of ASD.
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Affiliation(s)
- Manuel F Casanova
- Department of Psychiatry, University of Louisville, 500 South Preston Street, Building A, Room 217, Louisville, KY 40202, United States.
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18
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Williams AJ, Umemori H. The best-laid plans go oft awry: synaptogenic growth factor signaling in neuropsychiatric disease. Front Synaptic Neurosci 2014; 6:4. [PMID: 24672476 PMCID: PMC3957327 DOI: 10.3389/fnsyn.2014.00004] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Accepted: 02/21/2014] [Indexed: 12/27/2022] Open
Abstract
Growth factors play important roles in synapse formation. Mouse models of neuropsychiatric diseases suggest that defects in synaptogenic growth factors, their receptors, and signaling pathways can lead to disordered neural development and various behavioral phenotypes, including anxiety, memory problems, and social deficits. Genetic association studies in humans have found evidence for similar relationships between growth factor signaling pathways and neuropsychiatric phenotypes. Accumulating data suggest that dysfunction in neuronal circuitry, caused by defects in growth factor-mediated synapse formation, contributes to the susceptibility to multiple neuropsychiatric diseases, including epilepsy, autism, and disorders of thought and mood (e.g., schizophrenia and bipolar disorder, respectively). In this review, we will focus on how specific synaptogenic growth factors and their downstream signaling pathways might be involved in the development of neuropsychiatric diseases.
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Affiliation(s)
- Aislinn J Williams
- Department of Psychiatry, University of Michigan Ann Arbor, MI, USA ; Molecular and Behavioral Neuroscience Institute, University of Michigan Ann Arbor, MI, USA
| | - Hisashi Umemori
- Molecular and Behavioral Neuroscience Institute, University of Michigan Ann Arbor, MI, USA ; Department of Neurology, F.M. Kirby Neurobiology Center, Harvard Medical School, Boston Children's Hospital Boston, MA, USA
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19
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Main PAE, Thomas P, Esterman A, Fenech MF. Necrosis is increased in lymphoblastoid cell lines from children with autism compared with their non-autistic siblings under conditions of oxidative and nitrosative stress. Mutagenesis 2014; 28:475-84. [PMID: 23766106 DOI: 10.1093/mutage/get025] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Autism spectrum disorders are a heterogeneous group of neurodevelopmental conditions characterised by impairments in reciprocal social interaction, communication and stereotyped behaviours. As increased DNA damage events have been observed in a range of other neurological disorders, it was hypothesised that they would be elevated in lymphoblastoid cell lines (LCLs) obtained from children with autism compared with their non-autistic siblings. Six case-sibling pairs of LCLs from children with autistic disorder and their non-autistic siblings were obtained from the Autism Genetic Resource Exchange (AGRE) and cultured in standard RPMI-1640 tissue culture medium. Cells were exposed to medium containing either 0, 25, 50, 100 and 200 µM hydrogen peroxide (an oxidative stressor) or 0, 5, 10, 20 and 40 µM s-nitroprusside (a nitric oxide producer) for 1h. Following exposure, the cells were microscopically scored for DNA damage, cytostasis and cytotoxicity biomarkers as measured using the cytokinesis-block micronucleus cytome assay. Necrosis was significantly increased in cases relative to controls when exposed to oxidative and nitrosative stress (P = 0.001 and 0.01, respectively). Nuclear division index was significantly lower in LCLs from children with autistic disorder than their non-autistic siblings when exposed to hydrogen peroxide (P = 0.016), but there was no difference in apoptosis, micronucleus frequency, nucleoplasmic bridges or nuclear buds. Exposure to s-nitroprusside significantly increased the number of micronuclei in non-autistic siblings compared with cases (P = 0.003); however, other DNA damage biomarkers, apoptosis and nuclear division did not differ significantly between groups. The findings of this study show (i) that LCLs from children with autism are more sensitive to necrosis under conditions of oxidative and nitrosative stress than their non-autistic siblings and (ii) refutes the hypothesis that children with autistic disorder are abnormally susceptible to DNA damage.
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Affiliation(s)
- Penelope A E Main
- Sansom Institute of Health Research, University of South Australia, North Terrace, Adelaide, Australia
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20
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Parellada M, Penzol MJ, Pina L, Moreno C, González-Vioque E, Zalsman G, Arango C. The neurobiology of autism spectrum disorders. Eur Psychiatry 2013; 29:11-9. [PMID: 24275633 DOI: 10.1016/j.eurpsy.2013.02.005] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/19/2013] [Accepted: 02/20/2013] [Indexed: 01/22/2023] Open
Abstract
Data is progressively and robustly accumulating regarding the biological basis of autism. Autism spectrum disorders (ASD) are currently considered a group of neurodevelopmental disorders with onset very early in life and a complex, heterogeneous, multifactorial aetiology. A comprehensive search of the last five years of the Medline database was conducted in order to summarize recent evidence on the neurobiological bases of autism. The main findings on genetic influence, neuropathology, neurostructure and brain networks are summarized. In addition, findings from peripheral samples of subjects with autism and animal models, which show immune, oxidative, mitochondrial dysregulations, are reported. Then, other biomarkers from very different systems associated with autism are reported. Finally, an attempt is made to try and integrate the available evidence, which points to a oligogenetic, multifactorial aetiology that converges in an aberrant micro-organization of the cortex, with abnormal functioning of the synapses and abnormalities in very general physiological pathways (such as inflammatory, immune and redox systems).
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Affiliation(s)
- M Parellada
- Child and Adolescent Psychiatry Department, Instituto de Investigación Sanitaria Gregorio Marañón, IiSGM, Hospital General Universitario Gregorio Marañón, CIBERSAM, Ibiza 43, 28009 Madrid, Spain.
| | - M J Penzol
- Child and Adolescent Psychiatry Department, Instituto de Investigación Sanitaria Gregorio Marañón, IiSGM, Hospital General Universitario Gregorio Marañón, CIBERSAM, Ibiza 43, 28009 Madrid, Spain
| | - L Pina
- Child and Adolescent Psychiatry Department, Instituto de Investigación Sanitaria Gregorio Marañón, IiSGM, Hospital General Universitario Gregorio Marañón, CIBERSAM, Ibiza 43, 28009 Madrid, Spain
| | - C Moreno
- Child and Adolescent Psychiatry Department, Instituto de Investigación Sanitaria Gregorio Marañón, IiSGM, Hospital General Universitario Gregorio Marañón, CIBERSAM, Ibiza 43, 28009 Madrid, Spain
| | - E González-Vioque
- Child and Adolescent Psychiatry Department, Instituto de Investigación Sanitaria Gregorio Marañón, IiSGM, Hospital General Universitario Gregorio Marañón, CIBERSAM, Ibiza 43, 28009 Madrid, Spain
| | - G Zalsman
- Child and Adolescent Psychiatry, Geha Hospital, Petach Tiqva, 49100 Tel Aviv, Israel
| | - C Arango
- Child and Adolescent Psychiatry Department, Instituto de Investigación Sanitaria Gregorio Marañón, IiSGM, Hospital General Universitario Gregorio Marañón, CIBERSAM, Ibiza 43, 28009 Madrid, Spain
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21
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Favre MR, Barkat TR, LaMendola D, Khazen G, Markram H, Markram K. General developmental health in the VPA-rat model of autism. Front Behav Neurosci 2013; 7:88. [PMID: 23898245 PMCID: PMC3721005 DOI: 10.3389/fnbeh.2013.00088] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2013] [Accepted: 07/01/2013] [Indexed: 12/28/2022] Open
Abstract
Autism is a neurodevelopmental condition diagnosed by impaired social interaction, abnormal communication and, stereotyped behaviors. While post-mortem and imaging studies have provided good insights into the neurobiological symptomology of autism, animal models can be used to study the neuroanatomical, neurophysiological and molecular mediators in more detail and in a more controlled environment. The valproic acid (VPA) rat model is an environmentally triggered model with strong construct and clinical validity. It is based on VPA teratogenicity in humans, where mothers who are medicated with VPA during early pregnancy show an increased risk for giving birth to an autistic child. In rats, early embryonic exposure, around the time of neural tube closure, leads to autism-like anatomical and behavioral abnormalities in the offspring. Considering the increasing use of the VPA rat model, we present our observations of the general health of Wistar dams treated with a single intraperitoneal injection of 500 or, 600 mg/kg VPA on embryonic day E12.5, as well as their male and female offspring, in comparison to saline-exposed controls. We report increased rates of complete fetal reabsorption after both VPA doses. VPA 500 mg/kg showed no effect on dam body weight during pregnancy or, on litter size. Offspring exposed to VPA 500 mg/kg showed smaller brain mass on postnatal days 1 (P1) and 14 (P14), in addition to abnormal nest seeking behavior at P10 in the olfactory discrimination test, relative to controls. We also report increased rates of physical malformations in the offspring, rare occurrences of chromodacryorrhea and, developmentally similar body mass gain. Further documentation of developmental health may guide sub-grouping of individuals in a way to better predict core symptom severity.
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Affiliation(s)
- Mônica R. Favre
- Laboratory of Neural Microcircuits, Brain Mind Institute, École Polytechnique Fédérale de LausanneLausanne, Switzerland
| | - Tania R. Barkat
- Department of Neuroscience and Pharmacology, Copenhagen UniversityCopenhagen, Denmark
| | - Deborah LaMendola
- Laboratory of Neural Microcircuits, Brain Mind Institute, École Polytechnique Fédérale de LausanneLausanne, Switzerland
| | - Georges Khazen
- Computer Science and Mathematics Department, School of Arts and Sciences, Lebanese American UniversityByblos, Lebanon
| | - Henry Markram
- Laboratory of Neural Microcircuits, Brain Mind Institute, École Polytechnique Fédérale de LausanneLausanne, Switzerland
| | - Kamila Markram
- Laboratory of Neural Microcircuits, Brain Mind Institute, École Polytechnique Fédérale de LausanneLausanne, Switzerland
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22
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Zafeiriou DI, Ververi A, Dafoulis V, Kalyva E, Vargiami E. Autism spectrum disorders: the quest for genetic syndromes. Am J Med Genet B Neuropsychiatr Genet 2013; 162B:327-66. [PMID: 23650212 DOI: 10.1002/ajmg.b.32152] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2011] [Accepted: 03/01/2013] [Indexed: 11/10/2022]
Abstract
Autism spectrum disorders (ASD) are a heterogeneous group of neurodevelopmental disabilities with various etiologies, but with a heritability estimate of more than 90%. Although the strong correlation between autism and genetic factors has been long established, the exact genetic background of ASD remains unclear. A number of genetic syndromes manifest ASD at higher than expected frequencies compared to the general population. These syndromes account for more than 10% of all ASD cases and include tuberous sclerosis, fragile X, Down, neurofibromatosis, Angelman, Prader-Willi, Williams, Duchenne, etc. Clinicians are increasingly required to recognize genetic disorders in individuals with ASD, in terms of providing proper care and prognosis to the patient, as well as genetic counseling to the family. Vice versa, it is equally essential to identify ASD in patients with genetic syndromes, in order to ensure correct management and appropriate educational placement. During investigation of genetic syndromes, a number of issues emerge: impact of intellectual disability in ASD diagnoses, identification of autistic subphenotypes and differences from idiopathic autism, validity of assessment tools designed for idiopathic autism, possible mechanisms for the association with ASD, etc. Findings from the study of genetic syndromes are incorporated into the ongoing research on autism etiology and pathogenesis; different syndromes converge upon common biological backgrounds (such as disrupted molecular pathways and brain circuitries), which probably account for their comorbidity with autism. This review paper critically examines the prevalence and characteristics of the main genetic syndromes, as well as the possible mechanisms for their association with ASD.
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23
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Sharma JR, Arieff Z, Gameeldien H, Davids M, Kaur M, van der Merwe L. Association analysis of two single-nucleotide polymorphisms of the RELN gene with autism in the South African population. Genet Test Mol Biomarkers 2013; 17:93-8. [PMID: 23216241 PMCID: PMC3552159 DOI: 10.1089/gtmb.2012.0212] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND Autism (MIM209850) is a neurodevelopmental disorder characterized by a triad of impairments, namely impairment in social interaction, impaired communication skills, and restrictive and repetitive behavior. A number of family and twin studies have demonstrated that genetic factors play a pivotal role in the etiology of autistic disorder. Various reports of reduced levels of reelin protein in the brain and plasma in autistic patients highlighted the role of the reelin gene (RELN) in autism. There is no such published study on the South African (SA) population. AIMS The aim of the present study was to find the genetic association of intronic rs736707 and exonic rs362691 (single-nucleotide polymorphisms [SNPs] of the RELN gene) with autism in a SA population. METHODS Genomic DNA was isolated from cheek cell swabs from autistic (136) as well as control (208) subjects. The TaqMan(®) Real-Time polymerase chain reaction and genotyping assay was utilized to determine the genotypes. RESULTS A significant association of SNP rs736707, but not for SNP rs362691, with autism in the SA population is observed. CONCLUSION There might be a possible role of RELN in autism, especially for SA populations. The present study represents the first report on genetic association studies on the RELN gene in the SA population.
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Affiliation(s)
- Jyoti Rajan Sharma
- Biotechnology Department, Faculty of Natural Science, University of Western Cape, Bellville, South Africa
| | - Zainunisha Arieff
- Biotechnology Department, Faculty of Natural Science, University of Western Cape, Bellville, South Africa
| | - Hajirah Gameeldien
- Biotechnology Department, Faculty of Natural Science, University of Western Cape, Bellville, South Africa
| | - Muneera Davids
- Biotechnology Department, Faculty of Natural Science, University of Western Cape, Bellville, South Africa
| | - Mandeep Kaur
- Biotechnology Department, Faculty of Natural Science, University of Western Cape, Bellville, South Africa
- Computational Bioscience Research Center, King Abdullah University of Science and Technology, Thuwal, Kingdom of Saudi Arabia
| | - Lize van der Merwe
- Biostatistics Unit, Medical Research Council, Tygerberg, South Africa
- Department of Statistics, University of Western Cape, Cape Town, South Africa
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24
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Role of IL-6 in the etiology of hyperexcitable neuropsychiatric conditions: experimental evidence and therapeutic implications. Future Med Chem 2012. [DOI: 10.4155/fmc.12.156] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Many neuropsychiatric conditions are primed or triggered by different types of stressors. The mechanisms through which stress induces neuropsychiatric disease are complex and incompletely understood. A ‘double hit’ hypothesis of neuropsychiatric disease postulates that stress induces maladaptive behavior in two phases separated by a dormant period. Recent research shows that the pleiotropic cytokine IL-6 is released centrally and peripherally following physical and psychological stress. In this article, we analyze evidence from clinics and animal models suggesting that stress-induced elevation in the levels of IL-6 may play a key role in the etiology of a heterogeneous family of hyperexcitable central conditions including epilepsy, schizophrenic psychoses, anxiety and disorders of the autistic spectrum. The cellular mechanism leading to hyperexcitable conditions might be a decrease in inhibitory/excitatory synaptic balance in either or both temporal phases of the conditions. Following these observations, we discuss how they may have important implications for optimal prophylactic and therapeutic pharmacological treatment.
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25
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Smith JM, Xu J, Powell EM. Age dependent forebrain structural changes in mice deficient in the autism associated gene Met tyrosine kinase. Neuroimage Clin 2012; 1:66-74. [PMID: 24179738 PMCID: PMC3757733 DOI: 10.1016/j.nicl.2012.09.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2012] [Revised: 08/13/2012] [Accepted: 09/03/2012] [Indexed: 01/06/2023]
Abstract
The MET tyrosine kinase has been identified as a susceptibility gene in patients with autism spectrum disorders. MET is expressed in the forebrain during prenatal and postnatal development. After birth, MET participates in dendritic outgrowth and circuit formation. Alterations in neuronal development, particularly in the cerebral cortex, may contribute to the pathology of developmental disorders, including autism. Patients with autism can exhibit abnormal cortical volumes and head circumferences. We tested the hypothesis that impaired Met signaling during development alters forebrain structure. We have utilized a conditional mutant mouse line which expresses a kinase-dead Met restricted to the cerebral cortex and hippocampal structures. In these mice, we have used magnetic resonance imaging (MRI) to analyze the structure of the cerebral cortex and related structures across postnatal development. We found that the rostral cortex, caudal hippocampus, dorsal striatum, thalamus, and corpus callosum were all larger in adult, but not juvenile, mutant mice relative to control mice. The specificity of the changes suggests that aberrant expansion of the forebrain is consistent with continued axonal and dendritic growth, potentially leading to improper circuit formation and maintenance.
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Key Words
- ANOVA, analysis of variance
- Autism
- CC, corpus callosum
- Corpus callosum
- Frontal cortex
- H,hipp, hippocampus
- HGF, hepatocyte growth factor
- K–S, Kolmogorov–Smirnov
- MRI
- MRI, magnetic resonance imaging
- Met tyrosine kinase
- Mouse
- P, postnatal day
- PCR, polymerase chain reaction
- RARE, rapid acquisition relaxation enhancement
- SEM, standard error of the mean
- bp, base pairs
- ctx, cerebral cortex
- mm, millimeter
- str, striatum
- th,thal, thalamus
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Affiliation(s)
- Jacob M. Smith
- Program in Neuroscience, Graduate Program in Life Sciences, Graduate School, University of Maryland, Baltimore, MD, USA
| | - Jennifer Xu
- Department of Anatomy & Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Elizabeth M. Powell
- Program in Neuroscience, Graduate Program in Life Sciences, Graduate School, University of Maryland, Baltimore, MD, USA
- Department of Anatomy & Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA
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Abstract
Alterations in gyral form and complexity have been consistently noted in both autism and dyslexia. In this present study, we apply spherical harmonics, an established technique which we have exapted to estimate surface complexity of the brain, in order to identify abnormalities in gyrification between autistics, dyslexics, and controls. On the order of absolute surface complexity, autism exhibits the most extreme phenotype, controls occupy the intermediate ranges, and dyslexics exhibit lesser surface complexity. Here, we synthesize our findings which demarcate these three groups and review how factors controlling neocortical proliferation and neuronal migration may lead to these distinctive phenotypes.
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