Receptive language skills of adolescents and young adults with down or fragile X syndrome.

We investigated the receptive language of adolescents and young adults with Down syndrome (n = 25) or fragile X syndrome (n = 19). We were interested in syndrome differences and gender differences within fragile X. Comparison of the syndromes and MA-matched typically developing children (n = 24) revealed that individuals with the syndromes differed in relative achievements across the domains of receptive vocabulary, receptive syntax, and nonverbal cognition as well as in the organization of their linguistic knowledge. Comparison of males and females with fragile X revealed that each displayed synchronous development across the three domains, despite the fact that the receptive language levels of females surpassed that of males.