Fragile X syndrome

Pragmatic language is a characteristic weakness in the language profile of individuals with fragile X syndrome (FXS), the most frequent inherited cause of intellectual disability and among the most common known genetic causes of autism spectrum disorder (ASD). However, pragmatic language profiles in FXS are known to be highly heterogeneous, and influenced by other cognitive factors, sex, and ASD status. In this chapter, we review pragmatic strengths and weaknesses across males and females with FXS, including comparisons with individuals with Down syndrome (another form of intellectual disability) as well as the impact of ASD status on pragmatics in FXS. We also consider the role of related underlying mechanisms (e.g. theory of mind, hyperarousal) that may importantly impact pragmatic language profiles, and discuss sex-specific differences. We conclude this chapter with directions for continued investigation and clinical considerations for assessment and intervention.