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Cable J, Purcell RH, Robinson E, Vorstman JAS, Chung WK, Constantino JN, Sanders SJ, Sahin M, Dolmetsch RE, Shah B, Thurm A, Martin CL, Bearden CE, Mulle JG. Harnessing rare variants in neuropsychiatric and neurodevelopment disorders-a Keystone Symposia report. Ann N Y Acad Sci 2021; 1506:5-17. [PMID: 34342000 PMCID: PMC8688183 DOI: 10.1111/nyas.14658] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2021] [Accepted: 06/14/2021] [Indexed: 11/28/2022]
Abstract
Neurodevelopmental neuropsychiatric disorders, such as autism spectrum disorder and schizophrenia, have strong genetic risk components, but the underlying mechanisms have proven difficult to decipher. Rare, high-risk variants may offer an opportunity to delineate the biological mechanisms responsible more clearly for more common idiopathic diseases. Indeed, different rare variants can cause the same behavioral phenotype, demonstrating genetic heterogeneity, while the same rare variant can cause different behavioral phenotypes, demonstrating variable expressivity. These observations suggest convergent underlying biological and neurological mechanisms; identification of these mechanisms may ultimately reveal new therapeutic targets. At the 2021 Keystone eSymposium "Neuropsychiatric and Neurodevelopmental Disorders: Harnessing Rare Variants" a panel of experts in the field described significant progress in genomic discovery and human phenotyping and raised several consistent issues, including the need for detailed natural history studies of rare disorders, the challenges in cohort recruitment, and the importance of viewing phenotypes as quantitative traits that are impacted by rare variants.
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Affiliation(s)
| | - Ryan H. Purcell
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia
| | - Elise Robinson
- Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, Massachusetts
- Department of Epidemiology, Harvard T. H. Chan School of Public Health, Boston, Massachusetts
| | - Jacob A. S. Vorstman
- Department of Psychiatry and The Centre for Applied Genomics, Program in Genetics and Genome Biology, Hospital for Sick Children, Toronto, ON, Canada
- Department of Psychiatry, University of Toronto, Toronto, ON, Canada
| | - Wendy K. Chung
- Departments of Pediatrics and Medicine, Columbia University, New York, New York
- Simons Foundation, New York, New York
| | - John N. Constantino
- Department of Psychiatry, Washington University School of Medicine, St. Louis, Missouri
| | - Stephan J. Sanders
- Department of Psychiatry and Behavioral Sciences, UCSF Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA
| | - Mustafa Sahin
- Rosamund Stone Zander Translational Neuroscience Center, F.M. Kirby Neurobiology Center, Department of Neurology, Boston Children’s Hospital, Harvard Medical School, Boston, Massachusetts
| | | | - Bina Shah
- Project 8p Foundation, Commission on Novel Technologies for Neurodevelopmental CNVs, New York, New York
| | - Audrey Thurm
- Neurodevelopmental and Behavioral Phenotyping, NIMH, National Institutes of Health, Bethesda, Maryland
| | - Christa L. Martin
- Autism & Developmental Medicine Institute, Geisinger, Danville, Pennsylvania
| | - Carrie E. Bearden
- Integrative Center for Neurogenetics, Departments of Psychiatry and Biobehavioral Science and Psychology, University of California Los Angeles, Los Angeles, California
| | - Jennifer G. Mulle
- Department of Human Genetics, Emory University School of Medicine, Atlanta, Georgia
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McCracken JT, Anagnostou E, Arango C, Dawson G, Farchione T, Mantua V, McPartland J, Murphy D, Pandina G, Veenstra-VanderWeele J. Drug development for Autism Spectrum Disorder (ASD): Progress, challenges, and future directions. Eur Neuropsychopharmacol 2021; 48:3-31. [PMID: 34158222 PMCID: PMC10062405 DOI: 10.1016/j.euroneuro.2021.05.010] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 05/13/2021] [Accepted: 05/18/2021] [Indexed: 12/11/2022]
Abstract
In 2017, facing lack of progress and failures encountered in targeted drug development for Autism Spectrum Disorder (ASD) and related neurodevelopmental disorders, the ISCTM with the ECNP created the ASD Working Group charged to identify barriers to progress and recommending research strategies for the field to gain traction. Working Group international academic, regulatory and industry representatives held multiple in-person meetings, teleconferences, and subgroup communications to gather a wide range of perspectives on lessons learned from extant studies, current challenges, and paths for fundamental advances in ASD therapeutics. This overview delineates the barriers identified, and outlines major goals for next generation biomedical intervention development in ASD. Current challenges for ASD research are many: heterogeneity, lack of validated biomarkers, need for improved endpoints, prioritizing molecular targets, comorbidities, and more. The Working Group emphasized cautious but unwavering optimism for therapeutic progress for ASD core features given advances in the basic neuroscience of ASD and related disorders. Leveraging genetic data, intermediate phenotypes, digital phenotyping, big database discovery, refined endpoints, and earlier intervention, the prospects for breakthrough treatments are substantial. Recommendations include new priorities for expanded research funding to overcome challenges in translational clinical ASD therapeutic research.
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Affiliation(s)
- James T McCracken
- Department of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine at UCLA, Los Angeles, CA 90024, United States.
| | | | - Celso Arango
- Department of Child and Adolescent Psychiatry, Institute of Psychiatry and Mental Health, Hospital General Univesitario Gregorio Maranon, and School of Medicine, Universidad Complutense de Madrid, CIBERSAM, Madrid, Spain
| | - Geraldine Dawson
- Duke University Medical Center, Durham, North Carolina, United States
| | - Tiffany Farchione
- Food and Drug Administration, Silver Spring, Maryland, United States
| | - Valentina Mantua
- Food and Drug Administration, Silver Spring, Maryland, United States
| | | | - Declan Murphy
- Institute of Psychiatry, Psychology and Neuroscience, King's College De Crespigny Park, Denmark Hill, London SE5 8AF, United Kingdom
| | - Gahan Pandina
- Neuroscience Therapeutic Area, Janssen Research & Development, Pennington, New Jersey, United States
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Constantino JN. Response to "A Radical Change in Our Autism Research Strategy is Needed: Back to Prototypes" by Mottron et al. (2021). Autism Res 2021; 14:2221-2223. [PMID: 34077599 DOI: 10.1002/aur.2529] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Accepted: 04/20/2021] [Indexed: 12/21/2022]
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Constantino JN. New guidance to seekers of autism biomarkers: an update from studies of identical twins. Mol Autism 2021; 12:28. [PMID: 33875018 PMCID: PMC8056556 DOI: 10.1186/s13229-021-00434-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Accepted: 03/15/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The autism spectrum disorders (ASD) are common neuropsychiatric conditions of childhood for which the vast proportion of population risk is attributable to inheritance, and for which there exist few if any replicated biomarkers. MAIN BODY This commentary summarizes a set of recent studies involving identical (monozygotic, MZ) twins which, taken together, have significant implications for the search for biomarkers of inherited susceptibility to autism. A first is that variation-in-severity of the condition (above the threshold for clinical diagnosis) appears more strongly influenced by stochastic/non-shared environmental influences than by heredity. Second is that there exist disparate early behavioral predictors of the familial recurrence of autism, which are themselves strongly genetically influenced but largely independent from one another. The nature of these postnatal predictors is that they are trait-like, continuously distributed in the general population, and largely independent from variation in general cognition, thereby reflecting a developmental substructure for familial autism. A corollary of these findings is that autism may arise as a developmental consequence of an allostatic load of earlier-occurring liabilities, indexed by early behavioral endophenotypes, in varying permutations and combinations. The clinical threshold can be viewed as a "tipping point" at which stochastic influences and/or other non-shared environmental influences assert much stronger influence on variation-in-severity (a) than do the genetic factors which contributed to the condition in the first place, and (b) than is observed in typical development. CONCLUSION Biomarkers identified on the basis of association with clinical symptom severity in ASD may reflect effects rather than causes of autism. The search for biomarkers of pathogenesis may benefit from a greater focus on traits that predict autism recurrence, among both clinical and general populations. In case-control studies, salient developmental liabilities should be systematically measured in both cases and controls, to avoid the erosion in statistical power (i.e., to detect differences) that can occur if control subjects carry sub-clinical aggregations of the same unmeasured traits that exert causal influences on the development of autism.
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Affiliation(s)
- John N Constantino
- Department of Psychiatry, Washington University in St. Louis, 660 S Euclid Ave, Campus Box 8504, St. Louis, MO, 63110, USA.
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5
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Girault JB, Swanson MR, Meera SS, Grzadzinski RL, Shen MD, Burrows CA, Wolff JJ, Pandey J, John TS, Estes A, Zwaigenbaum L, Botteron KN, Hazlett HC, Dager SR, Schultz RT, Constantino JN, Piven J. Quantitative trait variation in ASD probands and toddler sibling outcomes at 24 months. J Neurodev Disord 2020; 12:5. [PMID: 32024459 PMCID: PMC7003330 DOI: 10.1186/s11689-020-9308-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Accepted: 01/21/2020] [Indexed: 12/28/2022] Open
Abstract
Background Younger siblings of children with autism spectrum disorder (ASD) are at increased likelihood of receiving an ASD diagnosis and exhibiting other developmental concerns. It is unknown how quantitative variation in ASD traits and broader developmental domains in older siblings with ASD (probands) may inform outcomes in their younger siblings. Methods Participants included 385 pairs of toddler siblings and probands from the Infant Brain Imaging Study. ASD probands (mean age 5.5 years, range 1.7 to 15.5 years) were phenotyped using the Autism Diagnostic Interview-Revised (ADI-R), the Social Communication Questionnaire (SCQ), and the Vineland Adaptive Behavior Scales, Second Edition (VABS-II). Siblings were assessed using the ADI-R, VABS-II, Mullen Scales of Early Learning (MSEL), and Autism Diagnostic Observation Schedule (ADOS) and received a clinical best estimate diagnosis at 24 months using DSM-IV-TR criteria (n = 89 concordant for ASD; n = 296 discordant). We addressed two aims: (1) to determine whether proband characteristics are predictive of recurrence in siblings and (2) to assess associations between proband traits and sibling dimensional outcomes at 24 months. Results Regarding recurrence risk, proband SCQ scores were found to significantly predict sibling 24-month diagnostic outcome (OR for a 1-point increase in SCQ = 1.06; 95% CI = 1.01, 1.12). Regarding quantitative trait associations, we found no significant correlations in ASD traits among proband-sibling pairs. However, quantitative variation in proband adaptive behavior, communication, and expressive and receptive language was significantly associated with sibling outcomes in the same domains; proband scores explained 9–18% of the variation in cognition and behavior in siblings with ASD. Receptive language was particularly strongly associated in concordant pairs (ICC = 0.50, p < 0.001). Conclusions Proband ASD symptomology, indexed by the SCQ, is a predictor of familial ASD recurrence risk. While quantitative variation in social communication and restricted and repetitive behavior were not associated among sibling pairs, standardized ratings of proband language and communication explained significant variation in the same domains in the sibling at 24 months, especially among toddlers with an ASD diagnosis. These data suggest that proband characteristics can alert clinicians to areas of developmental concern for young children with familial risk for ASD.
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Affiliation(s)
- Jessica B Girault
- Carolina Institute for Developmental Disabilities, University of North Carolina at Chapel Hill, Campus Box 3376, Chapel Hill, NC, 27599, USA.
| | - Meghan R Swanson
- Department of Psychology, School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, TX, USA
| | - Shoba S Meera
- Carolina Institute for Developmental Disabilities, University of North Carolina at Chapel Hill, Campus Box 3376, Chapel Hill, NC, 27599, USA.,National Institute of Mental Health and Neurosciences, Bangalore, India
| | - Rebecca L Grzadzinski
- Carolina Institute for Developmental Disabilities, University of North Carolina at Chapel Hill, Campus Box 3376, Chapel Hill, NC, 27599, USA
| | - Mark D Shen
- Carolina Institute for Developmental Disabilities, University of North Carolina at Chapel Hill, Campus Box 3376, Chapel Hill, NC, 27599, USA.,Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | | | - Jason J Wolff
- Department of Educational Psychology, University of Minnesota, Minneapolis, MN, USA
| | - Juhi Pandey
- Center for Autism Research, Children's Hospital of Philadelphia, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Tanya St John
- Department of Speech and Hearing Science, University of Washington, Seattle, WA, USA
| | - Annette Estes
- Department of Speech and Hearing Science, University of Washington, Seattle, WA, USA
| | | | - Kelly N Botteron
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO, USA
| | - Heather C Hazlett
- Carolina Institute for Developmental Disabilities, University of North Carolina at Chapel Hill, Campus Box 3376, Chapel Hill, NC, 27599, USA.,Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Stephen R Dager
- Department of Radiology, University of Washington Medical Center, Seattle, WA, USA
| | - Robert T Schultz
- Center for Autism Research, Children's Hospital of Philadelphia, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - John N Constantino
- Division of Child Psychiatry, Department of Psychiatry, Washington University School of Medicine, St. Louis, MO, USA
| | - Joseph Piven
- Carolina Institute for Developmental Disabilities, University of North Carolina at Chapel Hill, Campus Box 3376, Chapel Hill, NC, 27599, USA.,Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
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Castelbaum L, Sylvester CM, Zhang Y, Yu Q, Constantino JN. On the Nature of Monozygotic Twin Concordance and Discordance for Autistic Trait Severity: A Quantitative Analysis. Behav Genet 2019; 50:263-272. [PMID: 31853901 PMCID: PMC7355281 DOI: 10.1007/s10519-019-09987-2] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Revised: 11/22/2019] [Accepted: 11/26/2019] [Indexed: 01/12/2023]
Abstract
The characterizing features of autism spectrum disorder (ASD) are continuously distributed in nature; however, prior twin studies have not systematically incorporated this knowledge into estimations of concordance and discordance. We conducted a quantitative analysis of twin–twin similarity for autistic trait severity in three existing data sets involving 366 pairs of uniformly-phenotyped monozygotic (MZ) twins with and without ASD. Probandwise concordance for ASD was 96%; however, MZ trait correlations differed markedly for pairs with ASD trait burden below versus above the threshold for clinical diagnosis, with R2s on the order of 0.6 versus 0.1, respectively. Categorical MZ twin discordance for ASD diagnosis is rare and more appropriately operationalized by standardized quantification of twin–twin differences. Here we provide new evidence that although ASD itself is highly heritable, variation-in-severity of symptomatology above the diagnostic threshold is substantially influenced, in contrast, by non-shared environmental factors which may identify novel targets of early ASD amelioration.
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Affiliation(s)
- Lauren Castelbaum
- Department of Psychiatry, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Chad M Sylvester
- Department of Psychiatry, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Yi Zhang
- Department of Psychiatry, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Qiongru Yu
- Department of Psychiatry, Washington University School of Medicine, St. Louis, Missouri, USA
| | - John N Constantino
- Department of Psychiatry, Washington University School of Medicine, St. Louis, Missouri, USA. .,Department of Pediatrics, Washington University School of Medicine, 660 S. Euclid Avenue, Campus Box 8504, St. Louis, Missouri, 63110, USA.
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7
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Human–Robot Interaction in Autism Treatment: A Case Study on Three Pairs of Autistic Children as Twins, Siblings, and Classmates. Int J Soc Robot 2017. [DOI: 10.1007/s12369-017-0433-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Brukner-Wertman Y, Laor N, Golan O. Social (Pragmatic) Communication Disorder and Its Relation to the Autism Spectrum: Dilemmas Arising From the DSM-5 Classification. J Autism Dev Disord 2016; 46:2821-2829. [DOI: 10.1007/s10803-016-2814-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Deng W, Zou X, Deng H, Li J, Tang C, Wang X, Guo X. The Relationship Among Genetic Heritability, Environmental Effects, and Autism Spectrum Disorders: 37 Pairs of Ascertained Twin Study. J Child Neurol 2015; 30:1794-9. [PMID: 25873587 DOI: 10.1177/0883073815580645] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2014] [Accepted: 03/09/2015] [Indexed: 11/15/2022]
Abstract
Autism spectrum disorders (ASD) comprise a heterogeneous group of neurodevelopmental disorders that have strong heritability. To better understand the heritable factors in twins with clinically diagnosed ASD and to discuss the relationship between social impairments and genetic and environmental factors. In last 13 years, over 12,000 cases of ASD were diagnosed in the children's development and behavior center, the authors review 37 pairs of these twins, in each pair, and at least 1 twin had been diagnosed with an ASD, and found that the concordance rate was 80% [95% confidence interval (CI) 51.9-95.7%] for monozygotic twins and 13.6% (95% CI: 2.9-34.9%) for dizygotic twins. The heritability of social impairments for ASD was 60.9% (95% CI: 47.3-74.5%). In addition, the rate of nonshared environmental factors was 39.1% (95% CI: 25.5-52.7%), and there were no shared environmental effects. Genetics and special environmental effect play an important role on ASD social impairments.
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Affiliation(s)
- Wenlin Deng
- Children's Development Behavior Center, Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Xiaobing Zou
- Children's Development Behavior Center, Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Hongzhu Deng
- Children's Development Behavior Center, Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Jianying Li
- Children's Development Behavior Center, Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Chun Tang
- Children's Development Behavior Center, Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Xueqin Wang
- Department of Statistical Science School of Mathematics and Computational Science, Sun Yat-sen University, Guangdong, China
| | - Xiaobo Guo
- Department of Statistical Science School of Mathematics and Computational Science, Sun Yat-sen University, Guangdong, China
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Neuhaus E, Kresse A, Faja S, Bernier RA, Webb SJ. Face processing among twins with and without autism: social correlates and twin concordance. Soc Cogn Affect Neurosci 2015; 11:44-54. [PMID: 26137974 DOI: 10.1093/scan/nsv085] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Accepted: 06/26/2015] [Indexed: 01/21/2023] Open
Abstract
Autism spectrum disorder (ASD) has a strong heritable basis, as evidenced by twin concordance rates. Within ASD, symptom domains may arise via independent genetic contributions, with varying heritabilities and genetic mechanisms. In this article, we explore social functioning in the form of (i) electrophysiological and behavioral measures of face processing (P1 and N170) and (ii) social behavior among child and adolescent twins with (N = 52) and without ASD (N = 66). Twins without ASD had better holistic face processing and face memory, faster P1 responses and greater sensitivity to the effects of facial inversion on P1. In contrast, N170 responses to faces were similar across diagnosis, with more negative amplitudes for faces vs non-face images. Across the sample, stronger social skills and fewer social difficulties were associated with faster P1 and N170 responses to upright faces, and better face memory. Twins were highly correlated within pairs across most measures, but correlations were significantly stronger for monozygotic vs dizygotic pairs on N170 latency and social problems. We suggest common developmental influences across twins for face processing and social behavior, but highlight (i) neural speed of face processing and (ii) social difficulties as important avenues in the search for genetic underpinnings in ASD.
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Affiliation(s)
- Emily Neuhaus
- Center on Human Development & Disability, University of Washington, Center on Child Health, Behavior, & Development, Seattle Children's Research Institute, Department of Psychiatry & Behavioral Sciences, University of Washington, Seattle, WA, USA
| | - Anna Kresse
- Center on Human Development & Disability, University of Washington, Center on Child Health, Behavior, & Development, Seattle Children's Research Institute
| | - Susan Faja
- Boston Children's Hospital, Boston, MA, USA, and Harvard University, Boston, MA, USA
| | - Raphael A Bernier
- Center on Human Development & Disability, University of Washington, Department of Psychiatry & Behavioral Sciences, University of Washington, Seattle, WA, USA
| | - Sara Jane Webb
- Center on Human Development & Disability, University of Washington, Center on Child Health, Behavior, & Development, Seattle Children's Research Institute, Department of Psychiatry & Behavioral Sciences, University of Washington, Seattle, WA, USA,
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Murray AL, McKenzie K, Kuenssberg R, O'Donnell M. Are we under-estimating the association between autism symptoms?: The importance of considering simultaneous selection when using samples of individuals who meet diagnostic criteria for an autism spectrum disorder. J Autism Dev Disord 2015; 44:2921-30. [PMID: 24898911 DOI: 10.1007/s10803-014-2154-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The magnitude of symptom inter-correlations in diagnosed individuals has contributed to the evidence that autism spectrum disorders (ASD) is a fractionable disorder. Such correlations may substantially under-estimate the population correlations among symptoms due to simultaneous selection on the areas of deficit required for diagnosis. Using statistical simulations of this selection mechanism, we provide estimates of the extent of this bias, given different levels of population correlation between symptoms. We then use real data to compare domain inter-correlations in the Autism Spectrum Quotient, in those with ASD versus a combined ASD and non-ASD sample. Results from both studies indicate that samples restricted to individuals with a diagnosis of ASD potentially substantially under-estimate the magnitude of association between features of ASD.
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Affiliation(s)
- Aja Louise Murray
- Centre for Cognitive Ageing and Cognitive Epidemiology, University of Edinburgh, 7 George Square, Edinburgh, EH8 9JZ, UK,
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12
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Robinson EB, Koenen KC, McCormick MC, Munir K, Hallett V, Happé F, Plomin R, Ronald A. A multivariate twin study of autistic traits in 12-year-olds: testing the fractionable autism triad hypothesis. Behav Genet 2012; 42:245-55. [PMID: 21927971 PMCID: PMC3256271 DOI: 10.1007/s10519-011-9500-3] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2011] [Accepted: 08/20/2011] [Indexed: 10/17/2022]
Abstract
Autistic traits-social impairment, communication impairment, and restricted and repetitive behaviors and interests-are heritable in the general population. Previous analyses have consistently reported limited genetic and environmental overlap between autistic trait domains in samples assessed in middle childhood. Here we extend this research to parent-report data for 12-year-olds. Data from 5,944 pairs in the Twins Early Development Study were analyzed to explore the domain-specific heritability and degree of shared genetic and environmental influences across different autistic traits in the general population and among individuals scoring in the top 5% of each domain. Sex differences in the etiological estimates were also tested in these analyses. Autistic traits were moderately to highly heritable (0.58-0.88) at age 12. Bivariate genetic correlations in the full sample (0.18-0.40) and the extremes (0.24-0.67), as well as even lower unique environmental correlations, all suggested considerable fractionation of genetic and environmental influences across autistic trait domains, in line with previous findings.
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Affiliation(s)
- Elise B Robinson
- Department of Epidemiology, Harvard School of Public Health, 185 Cambridge St., Boston, MA 02114, USA.
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13
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Ronald A, Larsson H, Anckarsäter H, Lichtenstein P. A twin study of autism symptoms in Sweden. Mol Psychiatry 2011; 16:1039-47. [PMID: 20644553 DOI: 10.1038/mp.2010.82] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
This study aimed to identify empirically the number of factors underlying autism symptoms-social impairments, communication impairments, and restricted repetitive behaviors and interests-when assessed in a general population sample. It also investigated to what extent these autism symptoms are caused by the same or different genetic and environmental influences. Autistic symptoms were assessed in a population-based twin cohort of >12,000 (9- and 12-year-old) children by parental interviews. Confirmatory factor analyses, principal component analyses and multivariate structural equation model fitting were carried out. A multiple factor solution was suggested, with nearly all analyses pointing to a three-factor model for both boys and girls and at both ages. A common pathway twin model fit the data best, which showed that there were some underlying common genetic and environmental influences across the different autism dimensions, but also significant specific genetic effects on each symptom type. These results suggest that the autism triad consists of three partly independent dimensions when assessed in the general population, and that these different autism symptoms, to a considerable extent, have partly separate genetic influences. These findings may explain the large number of children who do not meet current criteria for autism but who show some autism symptoms. Molecular genetic research may benefit from taking a symptom-specific approach to finding genes associated with autism.
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Affiliation(s)
- A Ronald
- Centre for Brain and Cognitive Development, Department of Psychological Sciences, Birkbeck, University of London, London, UK.
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Ronald A, Hoekstra RA. Autism spectrum disorders and autistic traits: a decade of new twin studies. Am J Med Genet B Neuropsychiatr Genet 2011; 156B:255-74. [PMID: 21438136 DOI: 10.1002/ajmg.b.31159] [Citation(s) in RCA: 354] [Impact Index Per Article: 27.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2010] [Accepted: 11/30/2010] [Indexed: 11/11/2022]
Abstract
Researchers continue to pursue a better understanding of the symptoms, comorbidities, and causes of autism spectrum disorders. In this article we review more than 30 twin studies of autism spectrum disorders (ASDs) and autistic traits published in the last decade that have contributed to this endeavor. These twin studies have reported on the heritability of autism spectrum disorders and autistic traits in different populations and using different measurement and age groups. These studies have also stimulated debate and new hypotheses regarding why ASDs show substantial symptom heterogeneity, and what causes their comorbidity with intellectual disability, language delay, and other psychiatric disorders such as ADHD. These studies also reveal that the etiology of autism and autistic traits assessed in the general population is more similar than different, which contributes to the question of where the boundary lies between autism and typical development. Recent findings regarding molecular genetic and environmental causes of autism are discussed in the relation to these twin studies. Lastly, methodological assumptions of the twin design are given consideration, as well as issues of measurement. Future research directions are suggested to ensure that this decade is as productive as the last in attempting to disentangle the causes of autism spectrum disorders.
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Affiliation(s)
- Angelica Ronald
- Centre for Brain and Cognitive Development, Department of Psychological Sciences, Birkbeck, University of London, UK.
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16
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Kates WR, Ikuta I, Burnette CP. Gyrification patterns in monozygotic twin pairs varying in discordance for autism. Autism Res 2010; 2:267-78. [PMID: 19890876 DOI: 10.1002/aur.98] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
In order to disentangle genetic and environmental contributions to cortical anomalies in children with autism, we investigated cortical folding patterns in a cohort of 14 monozygotic (MZ) twin pairs who displayed a range of phenotypic discordance for autism, and 14 typically developing community controls. Cortical folding was assessed with the gyrification index, which was calculated on high resolution anatomic MR images. We found that the cortical folding patterns across most lobar regions of the cerebral cortex was highly discordant within MZ twin pairs. In addition, children with autism and their co-twins exhibited increased cortical folding in the right parietal lobe, relative to age- and gender-matched typical developing children. Increased folding in the right parietal lobe was associated with more symptoms of autism for co-twins. Finally, the robust association between cortical folding and IQ observed in typical children was not observed in either children with autism or their co-twins. These findings, which contribute to our understanding of the limits of genetic liability in autism, suggest that anomalies in the structural integrity of the cortex in this PDD may disrupt the association between cortical folding and intelligence that has been reported in typical individuals, and may account, in part, for the deficits in visual spatial attention and in social cognition that have been reported in children with autism.
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Affiliation(s)
- Wendy R Kates
- Department of Psychiatry and Behavioral Sciences, State University of New York at Upstate Medical University, Syracuse, New York 13210, USA.
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Relationship between symptom domains in autism spectrum disorders: a population based twin study. J Autism Dev Disord 2009; 39:1197-210. [PMID: 19373549 DOI: 10.1007/s10803-009-0736-1] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2008] [Accepted: 03/22/2009] [Indexed: 12/31/2022]
Abstract
Factor structure and relationship between core features of autism (social impairments, communication difficulties, and restricted, repetitive behaviours or interests (RRBIs)) were explored in 189 children from the Twins Early Development Study, diagnosed with autistic spectrum disorders (ASDs) using the Development and Wellbeing Assessment (DAWBA; Goodman et al. in J Child Psychol Psyc 41:645-655, 2000). A bottom-up approach (analysis 1) used principal component factor analysis of DAWBA items indicating five factors, the first three mapping on the triad. In analysis 2, applying top-down DSM-IV criteria, correlations between domains were modest, strongest between social and communication difficulties. Cross-twin cross-trait correlations suggested small shared genetic effects between RRBIs and other symptoms. These findings from a clinical sample of twins indicate a fractionation of social/communicative and RRBI symptoms in ASD.
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The 'fractionable autism triad': a review of evidence from behavioural, genetic, cognitive and neural research. Neuropsychol Rev 2008; 18:287-304. [PMID: 18956240 DOI: 10.1007/s11065-008-9076-8] [Citation(s) in RCA: 282] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2008] [Accepted: 09/13/2008] [Indexed: 10/21/2022]
Abstract
Autism is diagnosed on the basis of a triad of impairments in social interaction, communication, and flexible imaginative functions (with restricted and repetitive behaviors and interests; RRBIs). There has been a strong presumption that these different features of the syndrome are strongly intertwined and proceed from a common cause at the genetic, cognitive and neural levels. In this review we examine evidence for an alternative approach, considering the triad as largely 'fractionable'. We present evidence from our own twin studies, and review relevant literature on autism and autistic-like traits in other groups. We suggest that largely independent genes may operate on social skills/impairments, communication abilities, and RRBIs, requiring a change in molecular-genetic research approaches. At the cognitive level, we suggest that satisfactory accounts exist for each of the triad domains, but no single unitary account can explain both social and nonsocial features of autism. We discuss the implications of the fractionable-triad approach for both diagnosis and future research directions.
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Goin-Kochel RP, Mazefsky CA, Riley BP. Level of functioning in autism spectrum disorders: phenotypic congruence among affected siblings. J Autism Dev Disord 2007; 38:1019-27. [PMID: 17968643 DOI: 10.1007/s10803-007-0476-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2006] [Accepted: 10/08/2007] [Indexed: 11/30/2022]
Abstract
Little evidence supports that siblings with autism exhibit the same behaviors; however, some findings suggest that level of functioning shows familial aggregation. We tested this notion among multiplex families participating with the Autism Genetic Resource Exchange (AGRE) Consortium, using scores on the Peabody Picture Vocabulary Test-Third Edition (N = 204 families), the Ravens Colored Progressive Matrices (N = 226 families), and the Vineland Adaptive Behavior Scales (N = 348 families). Intraclass Correlation Coefficients revealed that siblings with autism/autism spectrum disorders (ASD) were more similar on measures of verbal and nonverbal IQ and adaptive functioning than were unrelated children with autism/ASD. Preliminary twin correlations indicated strong genetic effects for some skill domains and the influence of shared environmental factors for others.
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Affiliation(s)
- Robin P Goin-Kochel
- Molecular and Human Genetics, Baylor College of Medicine, Texas Children's Hospital, 6621 Fannin Street, CC1560, Houston, TX 77030, USA.
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