Expressive language profiles of verbally expressive adolescents and young adults with Down syndrome or fragile X syndrome

Purpose: In this study, the authors examined the expressive language abilities of a subset of highly verbally expressive adolescents and young adults with Down syndrome (DS) and those with fragile X syndrome (FXS) for evidence of syndromerelated differences. FXS gender differences were also examined in an exploratory fashion. Method: The authors evaluated 24 adolescents and young adults with DS, 17 adolescents and young adults with FXS, and 21 children with typical development (TD), with the groups matched on nonverbal mental age. Language ability was examined using the Oral and Written Language Scales (OWLS; Carrow-Woolfolk, 1995) and Developmental Sentence Scoring (DSS; Lee, 1974) scores derived from an oral narrative language sample. Results: Study analyses revealed the following group differences: The FXS group outperformed the DSand TD groupsonthe OWLS measure; the TD group outperformed both other groups on some of the DSS measures; the FXS group outperformed the DS group on the DSS Sentence Point measure; and females with FXS outperformed males with FXS on several measures. Conclusions: Results contribute to the ongoing construction of the language phenotypes of individuals with DS and individuals with FXS and support the conclusion that there are quantitative rather than qualitative differences in their expressive language profiles.