Language Development in Fragile X Syndrome: Syndrome-specific Features, Within-syndrome Variation, and Contributing Factors

This chapter reviews what is known about the language problems of individuals with fragile X syndrome (FXS). The chapter is organized into four major sections. The first section provides a comprehensive characterization of the language problems typically associated with FXS, describing the extent and profile of delays and impairments and, where possible, the syndrome-specific features of the linguistic profile. The second section describes withinsyndrome variation in the linguistic profile, emphasizing the relationship between language and gender and autism status. The third section considers the genetic and environmental factors that lead to the syndrome-specific features of, and within-syndrome variation in, the linguistic phenotype of FXS. The final section identifies important gaps in our knowledge of the language problems of FXS and suggests some directions for future research.