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Down syndrome. Effects on language development.

The newly formed picture that emerges from these recent investigations of language in children with Down syndrome must include the following: (a) language production among children with Down syndrome lags behind expected performance based on mental age; (b) in many children with Down syndrome language production skills are not commensurate with comprehension skills; the number of subjects who exhibit this uneven profile increases with age; (c) lexical and syntactic development are asynchronous in Down syndrome with syntax lagging behind; and (d) syntactic development, as measured by MLU, is characterized by periods of relatively rapid linear growth alternating with extended plateaus. Although answering some questions, these findings raise new issues that must be addressed. However, it seems clear that the traditional "slow-but-normal" characterization of the language of children with Down syndrome is no longer tenable. Instead, we must begin to think in terms of specific properties that are unique to the development of language by children with Down syndrome.