A Comparison of Pragmatic Language in Boys With Autism and Fragile X Syndrome

Purpose: Impaired pragmatic language (i.e., language use for social interaction) is a hallmark feature of both autism spectrum disorder (ASD) and fragile X syndrome (FXS), the most common known monogenic disorder associated with ASD. However, few cross-population comparisons of ASD and FXS have been conducted, and it is unclear whether pragmatic language profiles in these conditions overlap. Method: The authors used seminaturalistic and standardized assessment methods to characterize pragmatic language abilities of 29 school-aged boys with idiopathic ASD, 38 with FXS and comorbid ASD, 16 with FXS without ASD, 20 with Down syndrome, and 20 with typical development. Results: Similar severity of pragmatic language deficits was observed in both of the groups with ASD (idiopathic and fragile X-associated). ASD comorbidity had a detrimental effect on the pragmatic language skills of the boys with FXS. Some different patterns emerged across the two pragmatic assessment tools, with more robust group differences observed in pragmatics assessed in a seminaturalistic conversational context. Conclusion: These findings have implications for pragmatic language assessment and intervention, as well as for understanding the potential role of the fragile X gene, Fragile X Mental Retardation-1, in the pragmatic language phenotype of ASD.