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Language and traits of autism spectrum conditions: evidence of limited phenotypic and etiological overlap.

Abstract

Language difficulties have historically been viewed as integral to autism spectrum conditions (ASC), leading molecular genetic studies to consider whether ASC and language difficulties have overlapping genetic bases. The extent of genetic, and also environmental, overlap between ASC and language is, however, unclear. We hence conducted a twin study of the concurrent association between autistic traits and receptive language abilities. Internet-based language tests were completed by ~3,000 pairs of twins, while autistic traits were assessed via parent ratings. Twin model fitting explored the association between these measures in the full sample, while DeFries-Fulker analysis tested these associations at the extremes of the sample. Phenotypic associations between language ability and autistic traits were modest and negative. The degree of genetic overlap was also negative, indicating that genetic influences on autistic traits lowered language scores in the full sample (mean genetic correlation = -0.13). Genetic overlap was also low at the extremes of the sample (mean genetic correlation = 0.14), indicating that genetic influences on quantitatively defined language difficulties were largely distinct from those on extreme autistic traits. Variation in language ability and autistic traits were also associated with largely different nonshared environmental influences. Language and autistic traits are influenced by largely distinct etiological factors. This has implications for molecular genetic studies of ASC and understanding the etiology of ASC. Additionally, these findings lend support to forthcoming DSM-5 changes to ASC diagnostic criteria that will see language difficulties separated from the core ASC communication symptoms, and instead listed as a clinical specifier.

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  • Authors+Show Affiliations

    ,

    Genes Environment Lifespan Laboratory, Centre for Brain and Cognitive Development, Department of Psychological Sciences, Birkbeck, University of London, London, UK.

    , , , , ,

    Source

    MeSH

    Autistic Disorder
    Child
    Diseases in Twins
    Female
    Follow-Up Studies
    Humans
    Language
    Longitudinal Studies
    Male
    Phenotype
    Prognosis
    Quantitative Trait, Heritable

    Pub Type(s)

    Journal Article
    Research Support, Non-U.S. Gov't
    Twin Study

    Language

    eng

    PubMed ID

    25088445

    Citation

    TY - JOUR T1 - Language and traits of autism spectrum conditions: evidence of limited phenotypic and etiological overlap. AU - Taylor,Mark J, AU - Charman,Tony, AU - Robinson,Elise B, AU - Hayiou-Thomas,Marianna E, AU - Happé,Francesca, AU - Dale,Philip S, AU - Ronald,Angelica, Y1 - 2014/08/02/ PY - 2014/06/12/received PY - 2014/06/26/accepted PY - 2014/8/5/entrez PY - 2014/8/5/pubmed PY - 2015/5/15/medline KW - autism KW - receptive language KW - twin study SP - 587 EP - 95 JF - American journal of medical genetics. Part B, Neuropsychiatric genetics : the official publication of the International Society of Psychiatric Genetics JO - Am. J. Med. Genet. B Neuropsychiatr. Genet. VL - 165B IS - 7 N2 - Language difficulties have historically been viewed as integral to autism spectrum conditions (ASC), leading molecular genetic studies to consider whether ASC and language difficulties have overlapping genetic bases. The extent of genetic, and also environmental, overlap between ASC and language is, however, unclear. We hence conducted a twin study of the concurrent association between autistic traits and receptive language abilities. Internet-based language tests were completed by ~3,000 pairs of twins, while autistic traits were assessed via parent ratings. Twin model fitting explored the association between these measures in the full sample, while DeFries-Fulker analysis tested these associations at the extremes of the sample. Phenotypic associations between language ability and autistic traits were modest and negative. The degree of genetic overlap was also negative, indicating that genetic influences on autistic traits lowered language scores in the full sample (mean genetic correlation = -0.13). Genetic overlap was also low at the extremes of the sample (mean genetic correlation = 0.14), indicating that genetic influences on quantitatively defined language difficulties were largely distinct from those on extreme autistic traits. Variation in language ability and autistic traits were also associated with largely different nonshared environmental influences. Language and autistic traits are influenced by largely distinct etiological factors. This has implications for molecular genetic studies of ASC and understanding the etiology of ASC. Additionally, these findings lend support to forthcoming DSM-5 changes to ASC diagnostic criteria that will see language difficulties separated from the core ASC communication symptoms, and instead listed as a clinical specifier. SN - 1552-485X UR - https://www.unboundmedicine.com/medline/citation/25088445/Language_and_traits_of_autism_spectrum_conditions:_Evidence_of_limited_phenotypic_and_etiological_overlap_ L2 - https://dx.doi.org/10.1002/ajmg.b.32262 ER -