The Broader Autism Phenotype in Parents of Children with Autism Spectrum Disorder: Implications for the Diagnostic Process and Relationship to Child Autism Spectrum Disorder Phenotype

Parents of children diagnosed with autism spectrum disorder (ASD) often exhibit social tendencies similar to ASD, but functioning is not impaired nor reaches levels of clinical significance. This constellation of sub-threshold diagnostic ASD traits is referred to as the broader autism phenotype (BAP) and includes features like pragmatic and communication difficulties and poor social skills. BAP is more common in families with children who have ASD and has neurological components and genetic origins, which make it a promising area for etiologic ASD research. The purpose of this dissertation was to explore two questions related to BAP in parents of children with ASD: 1) to assess the effect of BAP on discordance between maternal reported and clinician observed or estimated instruments reporting child ASD and 2) examine whether child ASD phenotype differs by parental BAP status. Data from the Study to Explore Early Development, a multi-site, community-based, case-control study of children aged 3-5 years with ASD, were used for all analyses. For our first aim, we used a sample of 712 mother-child dyads referred to SEED from educational and health providers of children with developmental delays who completed BAP and child ASD evaluations. BAP was positively associated with mothers meeting thresholds for child ASD on screeners or interviews when clinician reported instruments of child ASD did not (Risk ratios ranging from 1.45 to 2.52). Reporting discordances should be acknowledged and accounted for when diagnosing ASD. In aim two, we used SEED data to derive latent classes for child ASD phenotype from multiple behavioral and developmental measures. BAP in at least one parent was associated with the child having increased odds of being in the class with average non-verbal functioning, mild language and motor delays, and co-occurring conditions like anxiety and depression (OR: 2.44, 95% CI: 1.16, 5.09). Exploratory analyses show similar results if the father alone had BAP. Child sex did not modify this relationship. Children of parents with BAP were more likely to have a phenotype qualitatively similar to BAP presentation; this may have implications for work exploring etiologic origins and crafting parent-mediated interventions.Doctor of Philosoph