Early development in infants at risk of childhood apraxia of speech: a longitudinal investigation.

This study examined early features of the heritable phenotype associated with childhood apraxia-of-speech (CAS). We compared speech and language development from 9 to 24 months of age in eight children at familial risk of CAS to that of eight infants with no such family history. At-risk infants scored lower on expressive language, speech development, and fine motor skills. Results support a broad, heritable verbal trait deficit for children at risk of CAS. Single case analyses showed poor prelinguistic speech development can dissociate from emerging receptive language and conceptualization skills, consistent with a deficit originating in speech motor control.