Language symptoms of developmental language disorders: An overview of autism, Down syndrome, fragile X, specific language impairment, and Williams syndrome

Language deficits occur in a variety of developmental disorders including autism spectrum disorders, Down syndrome, fragile X syndrome, specific language impairment, and Williams syndrome. This paper describes the specific pattern of linguistic deficits in each of these disorders in terms of speech production, semantic, and syntactic abilities as well as the relationship between cognitive and linguistic skills and the presence of a deviant or delayed pattern of development. In the spirit of synthesis across diverse literatures, preliminary comparisons among the language profiles of these disorders are made. The full picture, however, is incomplete given the current state of the literature, which tends to focus on the analysis of a narrow range of linguistic phenomena within a single disorder. The field is in need of research that systematically compares these disorders and leads to detailed descriptions of linguistic phenotypes of each disorder.