Specific language impairment

Specific language impairment, often shortened to SLI, is diagnosed when a child's language does not develop normally and the difficulties cannot be accounted for by generally slow development, physical abnormality of the speech apparatus, autism spectrum disorder, apraxia, acquired brain damage or hearing loss. Twin studies have shown that it is under genetic influence. Although language impairment can result from a single-gene mutation, this is unusual. More commonly it results from the combined influence of multiple genetic variants, each of which is found in the general population, as well as environmental influences. The condition is therefore defined largely by exclusion: it names a child whose language lags for reasons that the other listed causes do not explain.