Journal of Autism and Developmental Disorders

, Volume 44, Issue 8, pp 2013–2025 | Cite as

A Twin Study of Heritable and Shared Environmental Contributions to Autism

  • Thomas W. Frazier
  • Lee Thompson
  • Eric A. Youngstrom
  • Paul Law
  • Antonio Y. Hardan
  • Charis Eng
  • Nathan Morris
Original Paper

Abstract

The present study examined genetic and shared environment contributions to quantitatively-measured autism symptoms and categorically-defined autism spectrum disorders (ASD). Participants included 568 twins from the Interactive Autism Network. Autism symptoms were obtained using the Social Communication Questionnaire and Social Responsiveness Scale. Categorically-defined ASD was based on clinical diagnoses. DeFries-Fulker and liability threshold models examined etiologic influences. Very high heritability was observed for extreme autism symptom levels (\( {\text{h}}_{g}^{2} = . 9 2{-} 1. 20 \)). Extreme levels of social and repetitive behavior symptoms were strongly influenced by common genetic factors. Heritability of categorically-defined ASD diagnosis was comparatively low (.21, 95 % CI 0.15–0.28). High heritability of extreme autism symptom levels confirms previous observations of strong genetic influences on autism. Future studies will require large, carefully ascertained family pedigrees and quantitative symptom measurements.

Keywords

Autism Twins Genetic Heritability Environment Diagnosis 

Supplementary material

10803_2014_2081_MOESM1_ESM.doc (186 kb)
Supplementary material 1 (DOC 186 kb)

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Copyright information

© Springer Science+Business Media New York 2014

Authors and Affiliations

  • Thomas W. Frazier
    • 1
    • 2
  • Lee Thompson
    • 6
  • Eric A. Youngstrom
    • 5
  • Paul Law
    • 3
  • Antonio Y. Hardan
    • 4
  • Charis Eng
    • 2
    • 8
  • Nathan Morris
    • 7
  1. 1.Center for AutismThe Cleveland ClinicClevelandUSA
  2. 2.Genomic Medicine InstituteCleveland ClinicClevelandUSA
  3. 3.Department of Medical Informatics and the Interactive Autism NetworkKennedy Krieger InstituteBaltimoreUSA
  4. 4.Department of Psychiatry and Behavioral SciencesStanfordStanfordUSA
  5. 5.Department of PsychologyThe University of North Carolina at Chapel HillChapel HillUSA
  6. 6.Departments of Psychological SciencesCase Western Reserve UniversityClevelandUSA
  7. 7.Departments of Epidemiology and BiostatisticsCase Western Reserve UniversityClevelandUSA
  8. 8.Departments of GeneticsCase Western Reserve UniversityClevelandUSA

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