Fragile X syndrome (FXS) is the leading inherited cause of intellectual disability. The syndrome is caused by a single gene mutation on the X chromosome. Although individual differences are large, most individuals with FXS display weaknesses across all language and literacy domains compared with peers of the same chronological age with typical…

On average, language and communication characteristics of individuals with Down syndrome (the most common genetic cause of intellectual disability) follow a consistent profile. Despite considerable individual variability, receptive language is typically stronger than expressive language, with particular challenges in phonology and syntax. We…

Velo-cardio-facial syndrome (VCFS) is a genetic disorder caused by a microdeletion of chromosome 22q11.2. Although there is some variability, VCFS is associated with a characteristic physical, behavioral, and cognitive phenotype. This review article focuses on aspects of language and literacy development in VCFS, describing what is known and…

The impact of a disordered phonological system (expressive or receptive) on language development is examined. Research results and guidelines are presented for identification of critical intelligibility and phonological awareness deficiencies and for intervention. Options for expediting intelligibility gains and research findings on enhancing…