The broader autism phenotype in infancy: When does it emerge?

Sally J Ozonoff, Gregory S. Young, Ashleigh Belding, Monique Hill, Alesha Hill, Ted Hutman, Scott Johnson, Meghan Miller, Sally J Rogers, A. J. Schwichtenberg, Marybeth Steinfeld, Ana-Maria Iosif

Research output: Contribution to journalArticlepeer-review

197 Scopus citations


Objective This study had 3 goals, which were to examine the following: the frequency of atypical development, consistent with the broader autism phenotype, in high-risk infant siblings of children with autism spectrum disorder (ASD); the age at which atypical development is first evident; and which developmental domains are affected. Method A prospective longitudinal design was used to compare 294 high-risk infants and 116 low-risk infants. Participants were tested at 6, 12, 18, 24, and 36 months of age. At the final visit, outcome was classified as ASD, Typical Development (TD), or Non-TD (defined as elevated Autism Diagnostic Observation Schedule [ADOS] score, low Mullen Scale scores, or both). Results Of the high-risk group, 28% were classified as Non-TD at 36 months of age. Growth curve models demonstrated that the Non-TD group could not be distinguished from the other groups at 6 months of age, but differed significantly from the Low-Risk TD group by 12 months on multiple measures. The Non-TD group demonstrated atypical development in cognitive, motor, language, and social domains, with differences particularly prominent in the social-communication domain. Conclusions These results demonstrate that features of atypical development, consistent with the broader autism phenotype, are detectable by the first birthday and affect development in multiple domains. This highlights the necessity for close developmental surveillance of infant siblings of children with ASD, along with implementation of appropriate interventions as needed.

Original languageEnglish (US)
JournalJournal of the American Academy of Child and Adolescent Psychiatry
Issue number4
StatePublished - 2014


  • autism spectrum disorder
  • broader autism phenotype
  • infancy
  • siblings
  • social-communication

ASJC Scopus subject areas

  • Psychiatry and Mental health
  • Developmental and Educational Psychology


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