The impact of familial autism diagnoses on autism symptomatology in infants and toddlers

Debate regarding the etiology of Autism Spectrum Disorders (ASD) is on the rise with numerous theories being put forth. Currently, the theory with the most empirical support is the interaction of multiple genes. Many studies have provided evidence that as the incidence of ASD increases so do genetic similarities. However, very little research has focused on the presentation of ASD symptomatology in those individuals with or without ASD diagnoses who have biological relatives with or without ASD diagnoses. The aim of the current study was to first examine the percentage of toddlers with and without ASD who had biological relatives with ASD. Next, the impact familial ASD had on ASD symptomatology within infants and toddlers with and without diagnoses of ASD was investigated. In the first study, 438 toddlers with an ASD diagnosis and 1,071 who were atypically developing without an ASD diagnosis were examined. A greater percentage of toddlers with ASD were noted to have a biological relative with an identified ASD in comparison to atypically developing toddlers. In the second study, no significant differences emerged between groups dependent on familial ASD of symptoms of autism as measured by the Baby and Infant Screen for Children with aUtIsm Traits (BISCUIT). As such, despite previous research indicating a strong genetic link to ASD, this link is undoubtedly complex and not necessarily related to ASD symptomatology. Suggestions for further research are provided.

► Genetics play an integral role in the development of ASD.
► Toddlers with ASD were more likely to have a relative with ASD than those without ASD.
► Symptomatology of ASD did not differ based on whether or not a family member had ASD (i.e., multi-incidence families).