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Hooshmandi M, Wong C, Khoutorsky A. Dysregulation of translational control signaling in autism spectrum disorders. Cell Signal 2020; 75:109746. [PMID: 32858122 DOI: 10.1016/j.cellsig.2020.109746] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 08/17/2020] [Accepted: 08/18/2020] [Indexed: 11/27/2022]
Abstract
Deviations from the optimal level of mRNA translation are linked to disorders with high rates of autism. Loss of function mutations in genes encoding translational repressors such as PTEN, TSC1, TSC2, and FMRP are associated with autism spectrum disorders (ASDs) in humans and their deletion in animals recapitulates many ASD-like phenotypes. Importantly, the activity of key translational control signaling pathways such as PI3K-mTORC1 and ERK is frequently dysregulated in autistic patients and animal models and their normalization rescues many abnormal phenotypes, suggesting a causal relationship. Mutations in several genes encoding proteins not directly involved in translational control have also been shown to mediate ASD phenotypes via altered signaling upstream of translation. This raises the possibility that the dysregulation of translational control signaling is a converging mechanism not only in familiar but also in sporadic forms of autism. Here, we overview the current knowledge on translational signaling in ASD and highlight how correcting the activity of key pathways upstream of translation reverses distinct ASD-like phenotypes.
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Affiliation(s)
- Mehdi Hooshmandi
- Department of Anesthesia, Faculty of Dentistry, McGill University, Montreal, QC H3A 0G1, Canada
| | - Calvin Wong
- Department of Anesthesia, Faculty of Dentistry, McGill University, Montreal, QC H3A 0G1, Canada
| | - Arkady Khoutorsky
- Department of Anesthesia, Faculty of Dentistry, McGill University, Montreal, QC H3A 0G1, Canada.
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2
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Sanders SJ. Next-Generation Sequencing in Autism Spectrum Disorder. Cold Spring Harb Perspect Med 2019; 9:cshperspect.a026872. [PMID: 30420340 DOI: 10.1101/cshperspect.a026872] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Autism spectrum disorder (ASD) is a common disorder that causes substantial distress. Heritability studies consistently show a strong genetic contribution, raising the hope that identifying ASD-associated genetic variants will offer insights into neurobiology and ultimately therapeutics. Next-generation sequencing (NGS) enabled the identification of disruptive variants throughout protein-coding regions of the genome. Alongside large cohorts and novel statistical methods, these NGS methods revolutionized ASD gene discovery. NGS methods have also contributed substantially to functional genetic data, such as gene expression, used to understand the neurobiological consequences of disrupting these ASD-associated genes. These functional data are also critical for annotating the noncoding genome as whole-genome sequencing (WGS) begins to provide initial insights outside of protein-coding regions. NGS methods still have a major role to play, as do similarly transformative advances in stem cell and gene-editing methods, in translating genetic discoveries into a first generation of ASD therapeutics.
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Affiliation(s)
- Stephan J Sanders
- Department of Psychiatry, UCSF Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, California 94158
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3
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Abstract
The MAPK pathway is a prominent intracellular signaling pathway regulating various intracellular functions. Components of this pathway are mutated in a related collection of congenital syndromes collectively referred to as neuro-cardio-facio-cutaneous syndromes (NCFC) or Rasopathies. Recently, it has been appreciated that these disorders are associated with autism spectrum disorders (ASD). In addition, idiopathic ASD has also implicated the MAPK signaling cascade as a common pathway that is affected by many of the genetic variants that have been found to be linked to ASDs. This chapter describes the components of the MAPK pathway and how it is regulated. Furthermore, this chapter will highlight the various functions of the MAPK pathway during both embryonic development of the central nervous system (CNS) and its roles in neuronal physiology and ultimately, behavior. Finally, we will summarize the perturbations to MAPK signaling in various models of autism spectrum disorders and Rasopathies to highlight how dysregulation of this pivotal pathway may contribute to the pathogenesis of autism.
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4
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Fernandez BA, Scherer SW. Syndromic autism spectrum disorders: moving from a clinically defined to a molecularly defined approach. DIALOGUES IN CLINICAL NEUROSCIENCE 2018. [PMID: 29398931 PMCID: PMC5789213 DOI: 10.31887/dcns.2017.19.4/sscherer] [Citation(s) in RCA: 86] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Autism spectrum disorder (ASD) encompasses a group of neurodevelopmental conditions diagnosed solely on the basis of behavioral assessments that reveal social deficits. Progress has been made in understanding its genetic underpinnings, but most ASD-associated genetic variants, which include copy number variants (CNVs) and mutations in ASD-risk genes, account for no more than 1 % of ASD cases. This high level of genetic heterogeneity leads to challenges obtaining and interpreting genetic testing in clinical settings. The traditional definition of syndromic ASD is a disorder with a clinically defined pattern of somatic abnormalities and a neurobehavioral phenotype that may include ASD. Most have a known genetic cause. Examples include fragile X syndrome and tuberous sclerosis complex. We propose dividing syndromic autism into the following two groups: (i) ASD that occurs in the context of a clinically defined syndrome-recognizing these disorders depends on the familiarity of the clinician with the features of the syndrome, and the diagnosis is typically confirmed by targeted genetic testing (eg, mutation screening of FMR1); (ii) ASD that occurs as a feature of a molecularly defined syndrome-for this group of patients, ASD-associated variants are identified by genome-wide testing that is not hypothesis driven (eg, microarray, whole exome sequencing). These ASD groups cannot be easily clinically defined because patients with a given variant have variable somatic abnormalities (dysmorphism and birth defects). In this article, we review common diagnoses from the above categories and suggest a testing strategy for patients, guided by determining whether the individual has essential or complex ASD; patients in the latter group have multiple morphologic anomalies on physical examination. Finally, we recommend that the syndromic versus nonsyndromic designation ultimately be replaced by classification of ASD according to its genetic etiology, which will inform about the associated spectrum and penetrance of neurobehavioral and somatic manifestations.
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Affiliation(s)
- Bridget A Fernandez
- Disciplines of Genetics and Medicine, Faculty of Medicine, Memorial University of Newfoundland, St John's, NL Canada
| | - Stephen W Scherer
- The Center for Applied Genomics and Program in Genetics and Genomic Biology, The Hospital for Sick Children, Toronto, Ontario, Canada; McLaughlin Center and Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
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5
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Bilder DA, Bakian AV, Stevenson DA, Carbone PS, Cunniff C, Goodman AB, McMahon WM, Fisher NP, Viskochil D. Brief Report: The Prevalence of Neurofibromatosis Type 1 among Children with Autism Spectrum Disorder Identified by the Autism and Developmental Disabilities Monitoring Network. J Autism Dev Disord 2017; 46:3369-76. [PMID: 27465244 DOI: 10.1007/s10803-016-2877-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Neurofibromatosis type 1 (NF1) is an inherited neurocutaneous disorder associated with neurodevelopmental disorders including autism spectrum disorder (ASD). The frequency of ASD/NF1 co-occurrence has been subject to debate since the 1980s. This relationship was investigated in a large population-based sample of 8-year-old children identified with ASD (N = 12,271) by the Centers for Disease Control and Prevention's Autism and Developmental Disabilities Monitoring (ADDM) Network. Twenty-two (1-in-558) children with ASD had diagnosed NF1, exceeding NF1 general population estimates by four to five fold. Children with ASD/NF1 versus ASD without NF1 were significantly less likely to receive a community-based ASD diagnosis (p = 0.04) and understand non-verbal communication (p = 0.001). These findings underscore the importance of including social-communication ability among relevant developmental concerns in children with NF1.
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Affiliation(s)
- Deborah A Bilder
- Utah Autism Research Program, Department of Psychiatry, University of Utah, 650 Komas Drive, Suite 206, Salt Lake City, UT, 84108, USA.
| | - Amanda V Bakian
- Utah Autism Research Program, Department of Psychiatry, University of Utah, 650 Komas Drive, Suite 206, Salt Lake City, UT, 84108, USA
| | - David A Stevenson
- Division of Medical Genetics, University of Utah, Salt Lake City, UT, USA.,Division of Medical Genetics, Stanford University, California, USA
| | - Paul S Carbone
- Department of Pediatrics, University of Utah, Salt Lake City, UT, USA
| | - Christopher Cunniff
- Department of Pediatrics, University of Arizona, Tucson, AZ, USA.,Division of Medical Genetics, Weill Cornell Medical College, New York, USA
| | - Alyson B Goodman
- National Center on Birth Defects and Developmental Disabilities, Center for Disease Control and Prevention, Atlanta, GA, USA
| | - William M McMahon
- Department of Psychiatry, University of Utah, Salt Lake City, UT, USA
| | - Nicole P Fisher
- Department of Psychiatry, University of Utah, Salt Lake City, UT, USA
| | - David Viskochil
- Division of Medical Genetics, University of Utah, Salt Lake City, UT, USA
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6
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Young AMH, Chakrabarti B, Roberts D, Lai MC, Suckling J, Baron-Cohen S. From molecules to neural morphology: understanding neuroinflammation in autism spectrum condition. Mol Autism 2016; 7:9. [PMID: 26793298 PMCID: PMC4719563 DOI: 10.1186/s13229-016-0068-x] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Accepted: 01/04/2016] [Indexed: 12/31/2022] Open
Abstract
Growing evidence points toward a critical role for early (prenatal) atypical neurodevelopmental processes in the aetiology of autism spectrum condition (ASC). One such process that could impact early neural development is inflammation. We review the evidence for atypical expression of molecular markers in the amniotic fluid, serum, cerebrospinal fluid (CSF), and the brain parenchyma that suggest a role for inflammation in the emergence of ASC. This is complemented with a number of neuroimaging and neuropathological studies describing microglial activation. Implications for treatment are discussed.
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Affiliation(s)
- Adam M H Young
- Autism Research Centre, Department of Psychiatry, University of Cambridge, Douglas House, 18B Trumpington Road, Cambridge, UK ; School of Clinical Medicine, Addenbrookes Hospital, University of Cambridge, Cambridge, UK
| | - Bhismadev Chakrabarti
- Autism Research Centre, Department of Psychiatry, University of Cambridge, Douglas House, 18B Trumpington Road, Cambridge, UK ; Centre for Integrative Neuroscience and Neurodynamics, School of Psychology and Clinical Language Science, University of Reading, Reading, UK
| | - David Roberts
- School of Clinical Medicine, Addenbrookes Hospital, University of Cambridge, Cambridge, UK
| | - Meng-Chuan Lai
- Autism Research Centre, Department of Psychiatry, University of Cambridge, Douglas House, 18B Trumpington Road, Cambridge, UK ; Centre for Addiction and Mental Health and Department of Psychiatry, University of Toronto, Toronto, Canada ; Department of Psychiatry, National Taiwan University Hospital and College of Medicine, Taipei, Taiwan
| | - John Suckling
- Brain Mapping Unit, Department of Psychiatry, University of Cambridge, Cambridge, UK ; Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, UK
| | - Simon Baron-Cohen
- Autism Research Centre, Department of Psychiatry, University of Cambridge, Douglas House, 18B Trumpington Road, Cambridge, UK ; CLASS Clinic, Cambridgeshire and Peterborough NHS Foundation Trust, Cambridge, UK
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7
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Polyak A, Kubina RM, Girirajan S. Comorbidity of intellectual disability confounds ascertainment of autism: implications for genetic diagnosis. Am J Med Genet B Neuropsychiatr Genet 2015. [PMID: 26198689 DOI: 10.1002/ajmg.b.32338] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
While recent studies suggest a converging role for genetic factors towards risk for nosologically distinct disorders including autism, intellectual disability (ID), and epilepsy, current estimates of autism prevalence fail to take into account the impact of comorbidity of these disorders on autism diagnosis. We aimed to assess the effect of comorbidity on the diagnosis and prevalence of autism by analyzing 11 years (2000-2010) of special education enrollment data on approximately 6.2 million children per year. We found a 331% increase in the prevalence of autism from 2000 to 2010 within special education, potentially due to a diagnostic recategorization from frequently comorbid features such as ID. The decrease in ID prevalence equaled an average of 64.2% of the increase of autism prevalence for children aged 3-18 years. The proportion of ID cases potentially undergoing recategorization to autism was higher (P = 0.007) among older children (75%) than younger children (48%). Some US states showed significant negative correlations between the prevalence of autism compared to that of ID while others did not, suggesting state-specific health policy to be a major factor in categorizing autism. Further, a high frequency of autistic features was observed when individuals with classically defined genetic syndromes were evaluated for autism using standardized instruments. Our results suggest that current ascertainment practices are based on a single facet of autism-specific clinical features and do not consider associated comorbidities that may confound diagnosis. Longitudinal studies with detailed phenotyping and deep molecular genetic analyses are necessary to completely understand the cause of this complex disorder.
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Affiliation(s)
- Andrew Polyak
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania, 16802
| | - Richard M Kubina
- Department of Educational Psychology, Counseling, and Special Education, The Pennsylvania State University, University Park, Pennsylvania, 16802
| | - Santhosh Girirajan
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania, 16802.,Department of Anthropology, The Pennsylvania State University, University Park, Pennsylvania, 16802
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8
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Accordino RE, Lucarelli J, Yan AC. Cutaneous Disease in Autism Spectrum Disorder: A Review. Pediatr Dermatol 2015; 32:455-60. [PMID: 25824343 DOI: 10.1111/pde.12582] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Dermatologic comorbid symptoms and conditions in persons with autism spectrum disorder (ASD) are compelling for several reasons, including problems with tactile sensory dysfunction in this population, a large number of syndromes with dermatologic findings and high rates of autism, nutritional and hormonal problems in ASD and their dermatologic manifestations, and the potential for overrepresentation of dermatologic symptoms that are neurobehavioral in nature. The current article reviews the available literature on the prevalence of comorbid dermatologic symptoms and conditions in children with ASD and identifies strategies for diagnosing and managing cutaneous disease in this population.
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Affiliation(s)
- Robert E Accordino
- Division of Child and Adolescent Psychiatry, Massachusetts General Hospital, Boston, Massachusetts
| | - Jennifer Lucarelli
- Division of Developmental Medicine, Boston Children's Hospital, Boston, Massachusetts
| | - Albert C Yan
- Section of Pediatric Dermatology, Children's Hospital of Philadelphia, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
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9
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Schwetye KE, Gutmann DH. Cognitive and behavioral problems in children with neurofibromatosis type 1: challenges and future directions. Expert Rev Neurother 2014; 14:1139-52. [PMID: 25161109 DOI: 10.1586/14737175.2014.953931] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Cognitive and behavioral disorders affect nearly 80% of all children with the neurofibromatosis type 1 inherited cancer syndrome, and are among the most significant clinical manifestations for patients and their families. One of the barriers to successful therapeutic intervention is the wide spectrum of clinical phenotypic expression, ranging from visuospatial learning problems to social perceptual deficits (autism). Leveraging numerous small-animal models of neurofibromatosis type 1, several promising targets have been identified to treat the learning, attention, and autism spectrum phenotypes in this at-risk population. In this review, we provide an up-to-date summary of our current understanding of these disorders in NF1, and propose future research directions aimed at designing more effective therapeutic approaches and clinical trials.
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Affiliation(s)
- Katherine E Schwetye
- Department of Pathology, Division of Neuropathology, Washington University School of Medicine, Box 8111, 660 S. Euclid Avenue, St. Louis MO 63110, USA
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10
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Tsc2 Haploinsufficiency Has Limited Effects on Fetal Brain Cytokine Levels during Gestational Immune Activation. AUTISM RESEARCH AND TREATMENT 2014; 2014:761279. [PMID: 25114803 PMCID: PMC4119898 DOI: 10.1155/2014/761279] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/09/2014] [Accepted: 06/20/2014] [Indexed: 11/17/2022]
Abstract
Dysregulated TSC/mTOR signaling may play a pathogenetic role in forms of syndromic autism, such as autism associated with tuberous sclerosis, a genetic disorder caused by heterozygous TSC1 or TSC2 mutations. Environmental risk factors, such as gestational viral infections, may, in some cases, also contribute to the pathogenesis of autism and related neuropsychiatric disorders. We have recently found that a heterozygous Tsc2 mutation and the poly I:C model of maternal immune activation (MIA) interactively perturb fetal development and adult social behavior in mice, suggesting that these factors converge on shared pathways. TSC/mTOR signaling plays an important role in the modulation of immune responses, raising the possibility that the damage caused by MIA was greater in Tsc2+/− than in wildtype fetuses because of an exacerbated immune response in the mutants. Here, cytokine antibody arrays were employed to measure relative cytokine abundances in the fetal brain and the placenta during MIA. Cytokines were induced by gestational poly I:C but there was no obvious modulatory effect of Tsc2 haploinsufficiency. The data indicate that cytokine exposure during MIA is comparable in Tsc2 haploinsufficient and wildtype control fetuses, suggesting that downstream molecular and cellular processes may account for the interactive effects of Tsc2 haploinsufficiency and MIA.
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11
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Tinker J, Carbone PS, Viskochil D, Mathiesen A, Ma KN, Stevenson DA. Screening children with neurofibromatosis type 1 for autism spectrum disorder. Am J Med Genet A 2014; 164A:1706-12. [PMID: 24715629 DOI: 10.1002/ajmg.a.36549] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Accepted: 03/03/2014] [Indexed: 11/11/2022]
Abstract
Autism spectrum disorder (ASD) is reported to be increased in neurofibromatosis type 1 (NF1), but it's unknown if ASD screening tools are sensitive and specific for NF1. This study compared the rate at which children with NF1 screen-positive for two ASD screening tools [Modified Checklist for Autism in Toddlers (M-CHAT) and Childhood Autism Spectrum Test (CAST)] to the screen-positive rate of the general population. A retrospective cross-sectional observational design to investigate the association between children with NF1 and at risk status for ASD was used. Medical records of children between 16 months and 11 years of age seen in an NF Clinic were reviewed for an ASD screening questionnaire. There were no statistically significant differences in the screen-positive rate for ASD in NF1 compared to published controls, but mean CAST scores were higher in NF1.
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Affiliation(s)
- Jade Tinker
- Department of Pediatrics, University of Utah, Salt Lake City, Utah
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12
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Banerjee S, Riordan M, Bhat MA. Genetic aspects of autism spectrum disorders: insights from animal models. Front Cell Neurosci 2014; 8:58. [PMID: 24605088 PMCID: PMC3932417 DOI: 10.3389/fncel.2014.00058] [Citation(s) in RCA: 87] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2014] [Accepted: 02/07/2014] [Indexed: 01/26/2023] Open
Abstract
Autism spectrum disorders (ASDs) are a complex neurodevelopmental disorder that display a triad of core behavioral deficits including restricted interests, often accompanied by repetitive behavior, deficits in language and communication, and an inability to engage in reciprocal social interactions. ASD is among the most heritable disorders but is not a simple disorder with a singular pathology and has a rather complex etiology. It is interesting to note that perturbations in synaptic growth, development, and stability underlie a variety of neuropsychiatric disorders, including ASD, schizophrenia, epilepsy, and intellectual disability. Biological characterization of an increasing repertoire of synaptic mutants in various model organisms indicates synaptic dysfunction as causal in the pathophysiology of ASD. Our understanding of the genes and genetic pathways that contribute toward the formation, stabilization, and maintenance of functional synapses coupled with an in-depth phenotypic analysis of the cellular and behavioral characteristics is therefore essential to unraveling the pathogenesis of these disorders. In this review, we discuss the genetic aspects of ASD emphasizing on the well conserved set of genes and genetic pathways implicated in this disorder, many of which contribute to synapse assembly and maintenance across species. We also review how fundamental research using animal models is providing key insights into the various facets of human ASD.
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Affiliation(s)
- Swati Banerjee
- Department of Physiology, Center for Biomedical Neuroscience, School of Medicine, University of Texas Health Science Center San Antonio, TX, USA
| | - Maeveen Riordan
- Department of Physiology, Center for Biomedical Neuroscience, School of Medicine, University of Texas Health Science Center San Antonio, TX, USA
| | - Manzoor A Bhat
- Department of Physiology, Center for Biomedical Neuroscience, School of Medicine, University of Texas Health Science Center San Antonio, TX, USA
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13
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Adviento B, Corbin IL, Widjaja F, Desachy G, Enrique N, Rosser T, Risi S, Marco EJ, Hendren RL, Bearden CE, Rauen KA, Weiss LA. Autism traits in the RASopathies. J Med Genet 2014; 51:10-20. [PMID: 24101678 PMCID: PMC4230531 DOI: 10.1136/jmedgenet-2013-101951] [Citation(s) in RCA: 109] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
BACKGROUND Mutations in Ras/mitogen-activated protein kinase (Ras/MAPK) pathway genes lead to a class of disorders known as RASopathies, including neurofibromatosis type 1 (NF1), Noonan syndrome (NS), Costello syndrome (CS), and cardio-facio-cutaneous syndrome (CFC). Previous work has suggested potential genetic and phenotypic overlap between dysregulation of Ras/MAPK signalling and autism spectrum disorders (ASD). Although the literature offers conflicting evidence for association of NF1 and autism, there has been no systematic evaluation of autism traits in the RASopathies as a class to support a role for germline Ras/MAPK activation in ASDs. METHODS We examined the association of autism traits with NF1, NS, CS and CFC, comparing affected probands with unaffected sibling controls and subjects with idiopathic ASDs using the qualitative Social Communication Questionnaire (SCQ) and the quantitative Social Responsiveness Scale (SRS). RESULTS Each of the four major RASopathies showed evidence for increased qualitative and quantitative autism traits compared with sibling controls. Further, each RASopathy exhibited a distinct distribution of quantitative social impairment. Levels of social responsiveness show some evidence of correlation between sibling pairs, and autism-like impairment showed a male bias similar to idiopathic ASDs. CONCLUSIONS Higher prevalence and severity of autism traits in RASopathies compared to unaffected siblings suggests that dysregulation of Ras/MAPK signalling during development may be implicated in ASD risk. Evidence for sex bias and potential sibling correlation suggests that autism traits in the RASopathies share characteristics with autism traits in the general population and clinical ASD population and can shed light on idiopathic ASDs.
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Affiliation(s)
- Brigid Adviento
- Department of Psychiatry, University of California San Francisco, San Francisco, California, USA
- Institute for Human Genetics, University of California San Francisco, San Francisco, California, USA
| | - Iris L Corbin
- Department of Psychiatry, University of California San Francisco, San Francisco, California, USA
- Institute for Human Genetics, University of California San Francisco, San Francisco, California, USA
- Prenatal Diagnosis Center, Sutter Pacific Medical Foundation, San Francisco, California, USA
| | - Felicia Widjaja
- Department of Psychiatry, University of California San Francisco, San Francisco, California, USA
| | - Guillaume Desachy
- Department of Psychiatry, University of California San Francisco, San Francisco, California, USA
- Institute for Human Genetics, University of California San Francisco, San Francisco, California, USA
| | - Nicole Enrique
- Department of Psychology, Semel Institute for Neuroscience and Human Behavior, University of California Los Angeles, Los Angeles, California, USA
| | - Tena Rosser
- Department of Neurology, Children’s Hospital Los Angeles, Los Angeles, California, USA
| | - Susan Risi
- Department of Psychiatry, University of California San Francisco, San Francisco, California, USA
| | - Elysa J Marco
- Department of Child Neurology, University of California San Francisco, San Francisco, California, USA
| | - Robert L Hendren
- Department of Psychiatry, University of California San Francisco, San Francisco, California, USA
| | - Carrie E Bearden
- Department of Psychology, Semel Institute for Neuroscience and Human Behavior, University of California Los Angeles, Los Angeles, California, USA
- Department of Psychology, University of California Los Angeles, Los Angeles, California, USA
| | - Katherine A Rauen
- Institute for Human Genetics, University of California San Francisco, San Francisco, California, USA
- Department of Pediatrics Genetics, University of California San Francisco, San Francisco, California, USA
| | - Lauren A Weiss
- Department of Psychiatry, University of California San Francisco, San Francisco, California, USA
- Institute for Human Genetics, University of California San Francisco, San Francisco, California, USA
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14
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Garg S, Green J, Leadbitter K, Emsley R, Lehtonen A, Evans DG, Huson SM. Neurofibromatosis type 1 and autism spectrum disorder. Pediatrics 2013; 132:e1642-8. [PMID: 24190681 DOI: 10.1542/peds.2013-1868] [Citation(s) in RCA: 119] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
OBJECTIVE To determine the prevalence of autism spectrum disorder (ASD) in Neurofibromatosis Type 1 (NF1). METHODS Second-phase population-based epidemiologic study using an allcase NF1 registry in a defined UK 4.1 million population area. A total of 109 (52.7%) of 207 responders from the initial screening phase were grouped by using the parent-rated Social Responsiveness Scale (SRS) as significant ASD (SRS≥76; n = 32), moderate ASD (SRS ≥ 60<76; n = 29), or non-ASD (SRS <60, n = 48). Twenty-three cases from the significant ASD group, 16 from moderate ASD, and 8 from non-ASD (total n = 47), invited proportionately by random selection, were seen for detailed confirmatory ascertainment. Assessments on Autism Diagnostic Interview-Revised, Autism Diagnostic Observation Scale-Generic, and verbal IQ were combined by using standard Collaborative Program for Excellence in Autism criteria into an ASD categorization for each case (ASD, broad ASD with partial features, non-ASD). A preplanned weighted analysis was used to derive prevalence estimates for the whole population. RESULTS Fourteen (29.5%) of 47 showed ASD, 13 (27.7%) broad ASD, and 20 (42.5%) non-ASD. The ASD/broad ASD group showed male predominance (1.7:1.0), but did not differ significantly from the non-ASD group on IQ, age, socioeconomic status, inheritance, physical severity, or education. The population prevalence estimate is 24.9% ASD (95% confidence interval 13.1%-42.1%) and 20.8% broad ASD (95% confidence interval 10.0%-38.1%); a total of 45.7% showing some ASD spectrum phenotype. CONCLUSIONS Findings indicate high prevalence of ASD in NF1, with implications for clinical practice and further research into NF1 as a single-gene model for autism.
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Affiliation(s)
- Shruti Garg
- FRCPsych, Child and Adolescent Psychiatry, University of Manchester and Manchester Academic Health Sciences Centre, Royal Manchester Children's Hospital, Room 4.308, Jean McFarlane Building, Oxford Rd, Manchester M13 9PL, UK.
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15
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Persico AM, Napolioni V. Autism genetics. Behav Brain Res 2013; 251:95-112. [PMID: 23769996 DOI: 10.1016/j.bbr.2013.06.012] [Citation(s) in RCA: 190] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Revised: 06/03/2013] [Accepted: 06/04/2013] [Indexed: 12/22/2022]
Abstract
Autism spectrum disorder (ASD) is a severe neuropsychiatric disease with strong genetic underpinnings. However, genetic contributions to autism are extremely heterogeneous, with many different loci underlying the disease to a different extent in different individuals. Moreover, the phenotypic expression (i.e., "penetrance") of these genetic components is also highly variable, ranging from fully penetrant point mutations to polygenic forms with multiple gene-gene and gene-environment interactions. Furthermore, many genes involved in ASD are also involved in intellectual disability, further underscoring their lack of specificity in phenotypic expression. We shall hereby review current knowledge on the genetic basis of ASD, spanning genetic/genomic syndromes associated with autism, monogenic forms due to copy number variants (CNVs) or rare point mutations, mitochondrial forms, and polygenic autisms. Finally, the recent contributions of genome-wide association and whole exome sequencing studies will be highlighted.
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Affiliation(s)
- Antonio M Persico
- Child and Adolescent Neuropsychiatry Unit, University Campus Bio-Medico, Rome, Italy.
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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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Ehninger D. From genes to cognition in tuberous sclerosis: Implications for mTOR inhibitor-based treatment approaches. Neuropharmacology 2013; 68:97-105. [DOI: 10.1016/j.neuropharm.2012.05.015] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2012] [Revised: 05/03/2012] [Accepted: 05/13/2012] [Indexed: 01/27/2023]
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Walsh KS, Vélez JI, Kardel PG, Imas DM, Muenke M, Packer RJ, Castellanos FX, Acosta MT. Symptomatology of autism spectrum disorder in a population with neurofibromatosis type 1. Dev Med Child Neurol 2013; 55:131-138. [PMID: 23163951 DOI: 10.1111/dmcn.12038] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
AIM Difficulties in neurocognition and social interaction are the most prominent causes of morbidity and long-term disability in children with neurofibromatosis type 1 (NF1). Symptoms of attention-deficit-hyperactivity disorder (ADHD) have also been extensively recognized in NF1. However, systematic evaluation of symptoms of autism spectrum disorder (ASD) in children with NF1 has been limited. METHOD We present a retrospective, cross-sectional study of the prevalence of symptoms of ASD and ADHD and their relationship in a consecutive series of 66 patients from our NF1 clinic. The Social Responsiveness Scale and the Vanderbilt ADHD Diagnostic Parent Rating Scale were used to assess symptoms of ASD and ADHD. RESULTS Sixty-six participants (42 males, 24 females) were included in this study. Mean age at assessment was 10 years 11 months (SD 5 y 4 mo). Forty percent of our NF1 sample had raised symptom levels reaching clinical significance on the Social Responsiveness Scale (T ≥ 60), and 14% reached levels consistent with those seen in children with ASDs (T ≥ 75). These raised levels were not explained by NF1 disease severity or externalizing/internalizing behavioral disorders. There was a statistically significant relationship between symptoms of ADHD and ASD (χ(2) =9.11, df=1, p=0.003, φ=0.56). Particularly salient were the relationships between attention and hyperactivity deficits, with impairments in social awareness and social motivation. INTERPRETATION We found that symptoms of ASD in our NF1 population were raised, consistent with previous reports. Further characterization of the specific ASD symptoms and their impact on daily function is fundamental to the development and implementation of effective interventions in this population, which will probably include a combination of medical and behavioral approaches.
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Affiliation(s)
- Karin S Walsh
- The Jennifer and Daniel Gilbert Neurofibromatosis Institute, Washington, DC., Center for Neuroscience and Behavioral Medicine at Children's National Medical Center, Washington, DC
| | - Jorge I Vélez
- Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD
| | - Peter G Kardel
- The Jennifer and Daniel Gilbert Neurofibromatosis Institute, Washington, DC., Center for Neuroscience and Behavioral Medicine at Children's National Medical Center, Washington, DC
| | - Daniel M Imas
- The Jennifer and Daniel Gilbert Neurofibromatosis Institute, Washington, DC., Center for Neuroscience and Behavioral Medicine at Children's National Medical Center, Washington, DC
| | - Maximilian Muenke
- Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD
| | - Roger J Packer
- The Jennifer and Daniel Gilbert Neurofibromatosis Institute, Washington, DC., Center for Neuroscience and Behavioral Medicine at Children's National Medical Center, Washington, DC
| | - Francisco X Castellanos
- Phyllis Green and Randolph Cowen Institute for Pediatric Neuroscience, NYU Langone Medical Center, New York, NY., Nathan Kline Institute, Orangeburg, NY, USA
| | - Maria T Acosta
- The Jennifer and Daniel Gilbert Neurofibromatosis Institute, Washington, DC., Center for Neuroscience and Behavioral Medicine at Children's National Medical Center, Washington, DC., Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD
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A discovery resource of rare copy number variations in individuals with autism spectrum disorder. G3-GENES GENOMES GENETICS 2012; 2:1665-85. [PMID: 23275889 PMCID: PMC3516488 DOI: 10.1534/g3.112.004689] [Citation(s) in RCA: 139] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/01/2012] [Accepted: 10/24/2012] [Indexed: 12/15/2022]
Abstract
The identification of rare inherited and de novo copy number variations (CNVs) in human subjects has proven a productive approach to highlight risk genes for autism spectrum disorder (ASD). A variety of microarrays are available to detect CNVs, including single-nucleotide polymorphism (SNP) arrays and comparative genomic hybridization (CGH) arrays. Here, we examine a cohort of 696 unrelated ASD cases using a high-resolution one-million feature CGH microarray, the majority of which were previously genotyped with SNP arrays. Our objective was to discover new CNVs in ASD cases that were not detected by SNP microarray analysis and to delineate novel ASD risk loci via combined analysis of CGH and SNP array data sets on the ASD cohort and CGH data on an additional 1000 control samples. Of the 615 ASD cases analyzed on both SNP and CGH arrays, we found that 13,572 of 21,346 (64%) of the CNVs were exclusively detected by the CGH array. Several of the CGH-specific CNVs are rare in population frequency and impact previously reported ASD genes (e.g., NRXN1, GRM8, DPYD), as well as novel ASD candidate genes (e.g., CIB2, DAPP1, SAE1), and all were inherited except for a de novo CNV in the GPHN gene. A functional enrichment test of gene-sets in ASD cases over controls revealed nucleotide metabolism as a potential novel pathway involved in ASD, which includes several candidate genes for follow-up (e.g., DPYD, UPB1, UPP1, TYMP). Finally, this extensively phenotyped and genotyped ASD clinical cohort serves as an invaluable resource for the next step of genome sequencing for complete genetic variation detection.
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Potential opposite roles of the extracellular signal-regulated kinase (ERK) pathway in autism spectrum and bipolar disorders. Neurosci Biobehav Rev 2012; 36:2206-13. [DOI: 10.1016/j.neubiorev.2012.07.008] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2012] [Revised: 07/20/2012] [Accepted: 07/28/2012] [Indexed: 11/22/2022]
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Abstract
Advances in genetics and genomics have improved our understanding of autism spectrum disorders. As many genes have been implicated, we look to points of convergence among these genes across biological systems to better understand and treat these disorders.
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Abstract
Advances in genetics and genomics have improved our understanding of autism spectrum disorders. As many genes have been implicated, we look to points of convergence among these genes across biological systems to better understand and treat these disorders.
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Affiliation(s)
- Jamee M Berg
- Program in Neuroscience IDP, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
- Semel Institute for Neuroscience and Human Behavior, University of California, Los Angeles, CA 90095, USA
- Program in Neurogenetics, Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
| | - Daniel H Geschwind
- Semel Institute for Neuroscience and Human Behavior, University of California, Los Angeles, CA 90095, USA
- Program in Neurogenetics, Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
- Center for Autism Research and Treatment and Center for Neurobehavioral Genetics, Semel Institute for Neuroscience and Human Behavior, University of California, Los Angeles, CA 90095, USA
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Gestational immune activation and Tsc2 haploinsufficiency cooperate to disrupt fetal survival and may perturb social behavior in adult mice. Mol Psychiatry 2012; 17:62-70. [PMID: 21079609 PMCID: PMC3118259 DOI: 10.1038/mp.2010.115] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Approximately 40-50% of individuals affected by tuberous sclerosis (TSC) develop autism spectrum disorders (ASDs). One possible explanation for this partial penetrance is an interaction between TSC gene mutations and other risk factors such as gestational immune activation. In this study, we report the interactive effects of these two ASD risk factors in a mouse model of TSC. Combined, but not single, exposure had adverse effects on intrauterine survival. Additionally, provisional results suggest that these factors synergize to disrupt social approach behavior in adult mice. Moreover, studies in human populations are consistent with an interaction between high seasonal flu activity in late gestation and TSC mutations in ASD. Taken together, our studies raise the possibility of a gene × environment interaction between heterozygous TSC gene mutations and gestational immune activation in the pathogenesis of TSC-related ASD.
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Watanabe Y, Yano S, Niihori T, Aoki Y, Matsubara Y, Yoshino M, Matsuishi T. A familial case of LEOPARD syndrome associated with a high-functioning autism spectrum disorder. Brain Dev 2011; 33:576-9. [PMID: 21093184 DOI: 10.1016/j.braindev.2010.10.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2010] [Revised: 10/03/2010] [Accepted: 10/06/2010] [Indexed: 11/29/2022]
Abstract
A connection between LEOPARD syndrome (a rare autosomal dominant disorder) and autism spectrum disorders (ASDs) may exist. Of four related individuals (father and three sons) with LEOPARD syndrome, all patients exhibited clinical symptoms consistent with ASDs. Findings included aggressive behavior and impairment of social interaction, communication, and range of interests. The coexistence of LEOPARD syndrome and ASDs in the related individuals may be an incidental familial event or indicative that ASDs is associated with LEOPARD syndrome. There have been no other independent reports of the association of LEOPARD syndrome and ASDs. Molecular and biochemical mechanisms that may suggest a connection between LEOPARD syndrome and ASDs are discussed.
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Affiliation(s)
- Yoriko Watanabe
- Department of Pediatrics and Child Health, Kurume University School of Medicine, 67 Asahi-machi, Kurume, Japan.
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Legendre CM, Charpentier-Côté C, Drouin R, Bouffard C. Neurofibromatosis type 1 and the "elephant man's" disease: the confusion persists: an ethnographic study. PLoS One 2011; 6:e16409. [PMID: 21347399 PMCID: PMC3036577 DOI: 10.1371/journal.pone.0016409] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2010] [Accepted: 12/22/2010] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND In 1986, two Canadian geneticists had demonstrated that Joseph Merrick, better known as the Elephant Man, suffered from the Proteus syndrome and not from neurofibromatosis type 1 (NF1), as was alleged by dermatologist Parkes in 1909. Despite this and although the two diseases differ at several levels: prevalence, diagnostic criteria, clinical manifestations and transmission, the confusion between NF1 and the "elephant man's" disease continues in medical and social representations by current linguistic usage, and in some media reports. With this article, we want to 1) document the persistence and extent of this fallacy, 2) identify certain critical factors that contribute to its persistence, and 3) evaluate its impact on the health and well being of patients with NF1 and their family members. METHODOLOGY Participant observation in the course of an ethnographic study on intergenerational dialogue between individuals with neurofibromatosis and their parents - Analysis of the scientific literature and of pinpoint articles in the print and online news media. FINDINGS Our findings show that because physicians have little knowledge about NF1, several print and online news media and a lot of physicians continue to make the confusion between NF1 and the disease the "elephant man". This misconception contributes to misinformation about the disease, feeding prejudices against affected patients, exacerbating the negative impacts of the disease on their quality of life, their cognitive development, their reproductive choices, as well as depriving them of proper care and appropriate genetic counseling. CONCLUSION If family physicians and pediatricians were properly informed about the disease, they could refer their patients with NF1 to NF clinics and to specialists. Thus, patients and their family members would benefit from better-tailored clinical management of their cases, perhaps even optimal management. [corrected]
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Affiliation(s)
- Claire-Marie Legendre
- Division of Genetics, Department of Pediatrics, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Québec, Canada.
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Ehninger D, Silva AJ. Rapamycin for treating Tuberous sclerosis and Autism spectrum disorders. Trends Mol Med 2011; 17:78-87. [PMID: 21115397 PMCID: PMC3075964 DOI: 10.1016/j.molmed.2010.10.002] [Citation(s) in RCA: 163] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2010] [Revised: 10/02/2010] [Accepted: 10/04/2010] [Indexed: 12/20/2022]
Abstract
Tuberous sclerosis (TSC) is a genetic disorder caused by heterozygous mutations in the TSC1 or TSC2 genes and is associated with autism spectrum disorders (ASD) in 20-60% of cases. In addition, altered TSC/mTOR signaling is emerging as a feature common to a subset of ASD. Recent findings, in animal models, show that restoration of the underlying molecular defect can improve neurological dysfunction in several of these models, even if treatment is initiated in adult animals, suggesting that pathophysiological processes in the mature brain contribute significantly to the overall neurological phenotype in these models. These findings suggest that windows for therapeutic intervention in ASD could be wider than thought previously.
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Affiliation(s)
- Dan Ehninger
- DZNE, German Center for Neurodegenerative Diseases, Ludwig-Erhard-Allee 2, 53175 Bonn, Germany,
| | - Alcino J. Silva
- University of California – Los Angeles, Departments of Neurobiology, Psychiatry & Biobehavioral Sciences, Psychology and the Brain Research Institute, 695 Charles E. Young Dr South, Los Angeles, CA 90095, USA,
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Betancur C. Etiological heterogeneity in autism spectrum disorders: more than 100 genetic and genomic disorders and still counting. Brain Res 2010; 1380:42-77. [PMID: 21129364 DOI: 10.1016/j.brainres.2010.11.078] [Citation(s) in RCA: 578] [Impact Index Per Article: 41.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2010] [Revised: 11/22/2010] [Accepted: 11/23/2010] [Indexed: 12/31/2022]
Abstract
There is increasing evidence that autism spectrum disorders (ASDs) can arise from rare highly penetrant mutations and genomic imbalances. The rare nature of these variants, and the often differing orbits of clinical and research geneticists, can make it difficult to fully appreciate the extent to which we have made progress in understanding the genetic etiology of autism. In fact, there is a persistent view in the autism research community that there are only a modest number of autism loci known. We carried out an exhaustive review of the clinical genetics and research genetics literature in an attempt to collate all genes and recurrent genomic imbalances that have been implicated in the etiology of ASD. We provide data on 103 disease genes and 44 genomic loci reported in subjects with ASD or autistic behavior. These genes and loci have all been causally implicated in intellectual disability, indicating that these two neurodevelopmental disorders share common genetic bases. A genetic overlap between ASD and epilepsy is also apparent in many cases. Taken together, these findings clearly show that autism is not a single clinical entity but a behavioral manifestation of tens or perhaps hundreds of genetic and genomic disorders. Increased recognition of the etiological heterogeneity of ASD will greatly expand the number of target genes for neurobiological investigations and thereby provide additional avenues for the development of pathway-based pharmacotherapy. Finally, the data provide strong support for high-resolution DNA microarrays as well as whole-exome and whole-genome sequencing as critical approaches for identifying the genetic causes of ASDs.
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Careaga M, Van de Water J, Ashwood P. Immune dysfunction in autism: a pathway to treatment. Neurotherapeutics 2010; 7:283-92. [PMID: 20643381 PMCID: PMC5084232 DOI: 10.1016/j.nurt.2010.05.003] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2010] [Revised: 05/18/2010] [Accepted: 05/18/2010] [Indexed: 11/22/2022] Open
Abstract
Autism is a complex and clinically heterogeneous disorder with a spectrum of symptoms. Clinicians, schools, and service agencies worldwide have reported a dramatic increase in the number of children identified with autism. Despite expanding research, the etiology and underlying biological processes of autism remain poorly understood, and the relative contribution from genetic, epigenetic, and environmental factors remains unclear. Although autism affects primarily brain function (especially affect, social functioning, and cognition), it is unknown to what extent other organs and systems are disrupted. Published findings have identified widespread changes in the immune systems of children with autism, at both systemic and cellular levels. Brain specimens from autism subjects exhibit signs of active, ongoing inflammation, as well as alterations in gene pathways associated with immune signaling and immune function. Moreover, many genetic studies have indicated a link between autism and genes that are relevant to both the nervous system and the immune system. Alterations in these pathways can affect function in both systems. Together, these reports suggest that autism may in fact be a systemic disorder with connections to abnormal immune responses. Such immune system dysfunction may represent novel targets for treatment. A better understanding of the involvement of the immune response in autism, and of how early brain development is altered, may have important therapeutic implications.
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Affiliation(s)
- Milo Careaga
- Department of Medical Microbiology and Immunology, University of California at Davis, 95817 Sacramento, California
- M.I.N.D. Institute, University of California at Davis, 2805 50th Street, 95817 Sacramento, CA
| | - Judy Van de Water
- Division of Rheumatology, Allergy and Clinical Immunology, University of California at Davis, 95817 Sacramento, California
| | - Paul Ashwood
- Department of Medical Microbiology and Immunology, University of California at Davis, 95817 Sacramento, California
- M.I.N.D. Institute, University of California at Davis, 2805 50th Street, 95817 Sacramento, CA
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Ploeger A, Raijmakers MEJ, van der Maas HLJ, Galis F. The association between autism and errors in early embryogenesis: what is the causal mechanism? Biol Psychiatry 2010; 67:602-7. [PMID: 19932467 DOI: 10.1016/j.biopsych.2009.10.010] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/26/2009] [Revised: 09/23/2009] [Accepted: 10/01/2009] [Indexed: 01/22/2023]
Abstract
The association between embryonic errors and the development of autism has been recognized in the literature, but the mechanism underlying this association remains unknown. We propose that pleiotropic effects during a very early and specific stage of embryonic development-early organogenesis-can explain this association. In humans early organogenesis is an embryonic stage, spanning Day 20 to Day 40 after fertilization, which is characterized by intense interactivity among body parts of the embryo. This implies that a single mutation or environmental disturbance affecting development at this stage can have several phenotypic effects (i.e., pleiotropic effects). Disturbances during early organogenesis can lead to many different anomalies, including limb deformities, craniofacial malformations, brain pathology, and anomalies in other organs. We reviewed the literature and found ample evidence for the association between autism and different kinds of physical anomalies, which agrees with the hypothesis that pleiotropic effects are involved in the development of autism. The proposed mechanism integrates findings from a variety of studies on autism, including neurobiological studies and studies on physical anomalies and prenatal influences on neurodevelopmental outcomes. The implication is that the origin of autism can be much earlier in embryologic development than has been frequently reported.
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Affiliation(s)
- Annemie Ploeger
- Department of Psychology, University of Amsterdam, 1018 WB Amsterdam, The Netherlands.
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Abstract
Autism spectrum disorder (ASD) is a behaviourally defined syndrome where the etiology and pathophysiology is only partially understood. In a small proportion of children with the condition, a specific medical disorder is identified, but the causal significance in many instances is unclear. Currently, the medical conditions that are best established as probable causes of ASD include Fragile X syndrome, Tuberous Sclerosis and abnormalities of chromosome 15 involving the 15q11-13 region. Various other single gene mutations, genetic syndromes, chromosomal abnormalities and rare de novo copy number variants have been reported as being possibly implicated in etiology, as have several ante and post natal exposures and complications. However, in most instances the evidence base for an association with ASD is very limited and largely derives from case reports or findings from small, highly selected and uncontrolled case series. Not only therefore, is there uncertainty over whether the condition is associated, but the potential basis for the association is very poorly understood. In some cases the medical condition may be a consequence of autism or simply represent an associated feature deriving from an underlying shared etiology. Nevertheless, it is clear that in a growing proportion of individuals potentially causal medical conditions are being identified and clarification of their role in etio-pathogenesis is necessary. Indeed, investigations into the causal mechanisms underlying the association between conditions such as tuberous sclerosis, Fragile X and chromosome 15 abnormalities are beginning to cast light on the molecular and neurobiological pathways involved in the pathophysiology of ASD. It is evident therefore, that much can be learnt from the study of probably causal medical disorders as they represent simpler and more tractable model systems in which to investigate causal mechanisms. Recent advances in genetics, molecular and systems biology and neuroscience now mean that there are unparalleled opportunities to test causal hypotheses and gain fundamental insights into the nature of autism and its development.
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Affiliation(s)
- Patrick F Bolton
- The Social Genetic & Developmental Psychiatry Centre and The Department of Child and Adolescent Psychiatry, The Institute of Psychiatry, King's College London, London, England,
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Levitt P, Campbell DB. The genetic and neurobiologic compass points toward common signaling dysfunctions in autism spectrum disorders. J Clin Invest 2009; 119:747-54. [PMID: 19339766 DOI: 10.1172/jci37934] [Citation(s) in RCA: 171] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Autism spectrum disorder (ASD) is a common neurodevelopmental disorder with high heritability. Here, we discuss data supporting the view that there are at least two distinct genetic etiologies for ASD: rare, private (de novo) single gene mutations that may have a large effect in causing ASD; and inherited, common functional variants of a combination of genes, each having a small to moderate effect in increasing ASD risk. It also is possible that a combination of the two mechanisms may occur in some individuals with ASD. We further discuss evidence from individuals with a number of different neurodevelopmental syndromes, in which there is a high prevalence of ASD, that some private mutations and common variants converge on dysfunctional ERK and PI3K signaling, which negatively impacts neurodevelopmental events regulated by some receptor tyrosine kinases.
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Affiliation(s)
- Pat Levitt
- Vanderbilt Kennedy Center for Research on Human Development and Department of Pharmacology,Vanderbilt University Medical Center, Nashville, Tennessee, USA.
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Krab LC, Goorden SM, Elgersma Y. Oncogenes on my mind: ERK and MTOR signaling in cognitive diseases. Trends Genet 2008; 24:498-510. [DOI: 10.1016/j.tig.2008.07.005] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2008] [Revised: 07/29/2008] [Accepted: 07/29/2008] [Indexed: 12/20/2022]
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Davis LK, Meyer KJ, Rudd DS, Librant AL, Epping EA, Sheffield VC, Wassink TH. Pax6 3' deletion results in aniridia, autism and mental retardation. Hum Genet 2008; 123:371-8. [PMID: 18322702 DOI: 10.1007/s00439-008-0484-x] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2007] [Accepted: 02/21/2008] [Indexed: 01/03/2023]
Abstract
The PAX6 gene is a transcription factor expressed early in development, predominantly in the eye, brain and gut. It is well known that mutations in PAX6 may result in aniridia, Peter's anomaly and kertatisis. Here, we present mutation analysis of a patient with aniridia, autism and mental retardation. We identified and characterized a 1.3 Mb deletion that disrupts PAX6 transcriptional activity and deletes additional genes expressed in the brain. Our findings provide continued evidence for the role of PAX6 in neural phenotypes associated with aniridia.
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Affiliation(s)
- L K Davis
- Department of Psychiatry, University of Iowa Carver College of Medicine, Iowa City, IA, USA.
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Buxbaum JD, Cai G, Nygren G, Chaste P, Delorme R, Goldsmith J, Råstam M, Silverman JM, Hollander E, Gillberg C, Leboyer M, Betancur C. Mutation analysis of the NSD1 gene in patients with autism spectrum disorders and macrocephaly. BMC MEDICAL GENETICS 2007; 8:68. [PMID: 18001468 PMCID: PMC2248565 DOI: 10.1186/1471-2350-8-68] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 08/06/2007] [Accepted: 11/14/2007] [Indexed: 11/10/2022]
Abstract
Background Sotos syndrome is an overgrowth syndrome characterized by macrocephaly, advanced bone age, characteristic facial features, and learning disabilities, caused by mutations or deletions of the NSD1 gene, located at 5q35. Sotos syndrome has been described in a number of patients with autism spectrum disorders, suggesting that NSD1 could be involved in other cases of autism and macrocephaly. Methods We screened the NSD1 gene for mutations and deletions in 88 patients with autism spectrum disorders and macrocephaly (head circumference 2 standard deviations or more above the mean). Mutation analysis was performed by direct sequencing of all exons and flanking regions. Dosage analysis of NSD1 was carried out using multiplex ligation-dependent probe amplification. Results We identified three missense variants (R604L, S822C and E1499G) in one patient each, but none is within a functional domain. In addition, segregation analysis showed that all variants were inherited from healthy parents and in two cases were also present in unaffected siblings, indicating that they are probably nonpathogenic. No partial or whole gene deletions/duplications were observed. Conclusion Our findings suggest that Sotos syndrome is a rare cause of autism spectrum disorders and that screening for NSD1 mutations and deletions in patients with autism and macrocephaly is not warranted in the absence of other features of Sotos syndrome.
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Affiliation(s)
- Joseph D Buxbaum
- Laboratory of Molecular Neuropsychiatry, Mount Sinai School of Medicine, New York, USA.
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Buxbaum JD, Cai G, Chaste P, Nygren G, Goldsmith J, Reichert J, Anckarsäter H, Rastam M, Smith CJ, Silverman JM, Hollander E, Leboyer M, Gillberg C, Verloes A, Betancur C. Mutation screening of the PTEN gene in patients with autism spectrum disorders and macrocephaly. Am J Med Genet B Neuropsychiatr Genet 2007; 144B:484-91. [PMID: 17427195 PMCID: PMC3381648 DOI: 10.1002/ajmg.b.30493] [Citation(s) in RCA: 223] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Mutations in the PTEN gene are associated with a broad spectrum of disorders, including Cowden syndrome (CS), Bannayan-Riley-Ruvalcaba syndrome, Proteus syndrome, and Lhermitte-Duclos disease. In addition, PTEN mutations have been described in a few patients with autism spectrum disorders (ASDs) and macrocephaly. In this study, we screened the PTEN gene for mutations and deletions in 88 patients with ASDs and macrocephaly (defined as >or=2 SD above the mean). Mutation analysis was performed by direct sequencing of all exons and flanking regions, as well as the promoter region. Dosage analysis of PTEN was carried out using multiplex ligation-dependent probe amplification (MLPA). No partial or whole gene deletions were observed. We identified a de novo missense mutation (D326N) in a highly conserved amino acid in a 5-year-old boy with autism, mental retardation, language delay, extreme macrocephaly (+9.6 SD) and polydactyly of both feet. Polydactyly has previously been described in two patients with Lhermitte-Duclos disease and CS and is thus likely to be a rare sign of PTEN mutations. Our findings suggest that PTEN mutations are a relatively infrequent cause of ASDs with macrocephaly. Screening of PTEN mutations is warranted in patients with autism and pronounced macrocephaly, even in the absence of other features of PTEN-related tumor syndromes.
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Affiliation(s)
- Joseph D. Buxbaum
- Laboratory of Molecular Neuropsychiatry, Mount Sinai School of Medicine, New York, New York
- Department of Psychiatry and Seaver Autism Research Center, Mount Sinai School of Medicine, New York, New York
| | - Guiqing Cai
- Laboratory of Molecular Neuropsychiatry, Mount Sinai School of Medicine, New York, New York
- Department of Psychiatry and Seaver Autism Research Center, Mount Sinai School of Medicine, New York, New York
| | - Pauline Chaste
- INSERM U513, Créteil, France
- Service de Psychopathologie de l’Enfant et de l’Adolescent, AP-HP, Hôpital Robert Debré, Paris, France
| | - Gudrun Nygren
- Department of Child and Adolescent Psychiatry, Goteborg University, Goteborg, Sweden
| | - Juliet Goldsmith
- Laboratory of Molecular Neuropsychiatry, Mount Sinai School of Medicine, New York, New York
- Department of Psychiatry and Seaver Autism Research Center, Mount Sinai School of Medicine, New York, New York
| | - Jennifer Reichert
- Laboratory of Molecular Neuropsychiatry, Mount Sinai School of Medicine, New York, New York
- Department of Psychiatry and Seaver Autism Research Center, Mount Sinai School of Medicine, New York, New York
| | - Henrik Anckarsäter
- Department of Child and Adolescent Psychiatry, Goteborg University, Goteborg, Sweden
| | - Maria Rastam
- Department of Child and Adolescent Psychiatry, Goteborg University, Goteborg, Sweden
| | - Christopher J. Smith
- Department of Psychiatry and Seaver Autism Research Center, Mount Sinai School of Medicine, New York, New York
| | - Jeremy M. Silverman
- Department of Psychiatry and Seaver Autism Research Center, Mount Sinai School of Medicine, New York, New York
| | - Eric Hollander
- Department of Psychiatry and Seaver Autism Research Center, Mount Sinai School of Medicine, New York, New York
| | - Marion Leboyer
- INSERM U513, Créteil, France
- Department of Psychiatry, AP-HP, Hôpital Henri Mondor et Hôpital Albert Chenevier, Créteil, France
| | - Christopher Gillberg
- Department of Child and Adolescent Psychiatry, Goteborg University, Goteborg, Sweden
- Department of Psychiatry, Saint George’s Hospital Medical School, London, United Kingdom
| | - Alain Verloes
- Department of Genetics, AP-HP, Hôpital Robert Debré, Paris, France
| | - Catalina Betancur
- INSERM U513, Créteil, France
- Correspondence to: Dr. Catalina Betancur, INSERM U513, Faculté de Médecine, 8 rue du Général Sarrail, 94010 Créteil, Cedex, France.
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Abstract
Autism is one of the most heritable complex disorders, with compelling evidence for genetic factors and little or no support for environmental influence. The estimated prevalence of autism has increased since molecular genetic studies began, owing to loosening of diagnostic criteria and, more importantly, to more complete ascertainment strategies. This has led to a reduction in the sibling relative risk, but strong heritability estimates remain. It is essential to recognize that genetics is the only current approach to understanding the pathophysiology of autism in which there is not the usual concern about whether one is studying a consequence rather than a cause. There are hundreds, if not thousands, of patients with autism spectrum disorder with documented single-gene mutations or chromosomal abnormalities. Autism may be one of the most complex, yet strongly genetic, disorders in which chromosomal disorders, relatively rare highly penetrant mutations, and multiplicative effects of common variants all have support in different cases and families. The field of complex genetics is replete with many researchers and reviewers who want to promote their overly focused interest in one method at the exclusion of others. However, it is essential that the restricted interests of patients with autism not be reflected in overly restrictive genetic approaches if we are to better understand the genetics of autism in the most expeditious and thorough manner.
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Abstract
Autism spectrum disorders (ASD) are among the most heritable of all neuropsychiatric disorders. Discovery of autism susceptibility genes has been the focus of intense research efforts over the last 10 years, and current estimates suggest that 10 to 20 different interacting genes are involved. Evidence from twin and family studies demonstrates increased risk in family members not only for autistic disorder, but also for a milder constellation of similar symptoms referred to as the broader phenotype. In addition, several genetic syndromes and chromosomal anomalies have been associated with ASD. Large family studies using linkage-analysis techniques have demonstrated several chromosomal regions thought to harbor genes related to the disorder. Finally, specific candidate genes based on function and location have been explored; these studies are reviewed here.
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Affiliation(s)
- Sarah J Spence
- UCLA Center for Autism Research and Treatment, UCLA Neuropsychiatric Institute, and Mattel Children's Hospital at UCLA, David Geffen School of Medicine, Los Angeles, CA, USA
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Abstract
Autism is a disorder characterised by severe difficulties in social interaction and communication, and with unusual behaviours. Once thought of as rare, autism is now recognised as being common. The role of CNS factors in pathogenesis is suggested by high rates of seizure disorder; research has highlighted the role of several specific brain regions in syndrome pathogenesis. Autism is a strongly genetic disorder and probably arises because of multiple genes; recurrence rates in families with one child are high. Early intervention with various techniques is helpful in many cases. Some pharmacological agents may help with certain problematic behaviours but do not address the underlying cause of the disorder.
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Affiliation(s)
- Fred R Volkmar
- Child Study Center, Yale University, PO Box 207900, New Haven, CT 06520, USA.
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Abstract
OBJECTIVE To review systematically the empirical evidence for the involvement of genetic risk factors in infantile autism. METHOD We aimed at including all relevant papers written in English. We conducted a Medline search in September 2000. In addition we searched the reference lists of related papers. RESULTS A relatively small number of reports including family and twin studies, comorbidity, cytogenetic and molecular genetic studies were reviewed. CONCLUSION As well family, twin, cytogenetic and molecular genetic studies supported the importance of genetic risk factors in infantile autism. In most individual cases probably at least a few gene variants simultaneously determine the genetic risk. Presently the most interesting chromosome regions concerning the aetiology of autism are chromosomes 7q31-35, 15q11-13 and 16p13.3 which have been suggested by different lines of genetic research.
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Affiliation(s)
- M Lauritsen
- Department of Psychiatric Demography, Institute for Basic Psychiatric Research, Psychiatric Hospital in Aarhus, Aarhus University Hospital, DK-8240 Risskov, Denmark
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Abstract
OBJECTIVE To summarize recent advances about the nature, diagnosis, and treatment of pervasive developmental disorders. METHOD Review of Medline databases, books, and book chapters published between July 1989 and November 1999. RESULTS Clinical and genetic studies support expansion of the concept of autism to include a broader spectrum of social communication handicaps. The prevalence of autism is approximately 1 per 2,000; the prevalence of autism and Asperger's disorder together is 1 per 1,000. The Checklist for Autism in Toddlers is a useful screening instrument for 18-month-old children; the Autism Diagnostic Interview-Revised and the Autism Diagnostic Observation Schedule are instruments of choice for research. Although twin and family studies clearly support genetic factors as important in autism, linkage analysis studies indicate that many genes may be involved. There is no one treatment of choice. Social-pragmatic approaches, augmented by individualized strategies and social coaching, may be best for teaching social communication skills. Pharmacological interventions have a limited role in improving social communication, but selective serotonin reuptake inhibitors and atypical neuroleptic medications may help ameliorate aggression, hyperactivity, and other secondary problems. CONCLUSIONS Private and government agencies must continue to support basic and applied research.
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Affiliation(s)
- P E Tanguay
- Department of Psychiatry, University of Louisville School of Medicine, KY 40202, USA.
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