Early speech-language development in females with Rett syndrome: focusing on the preserved speech variant

Aim Our aim was to contribute new findings related to the pre‐regressional verbal development of females with a variant of Rett syndrome (RTT) as the loss of spoken language is one of the key clinical features of RTT, and it would be of particular interest to study the early speech–language development of females who are considered to have preserved some speech–language abilities. Method We analysed 461 minutes of audio–video recordings containing play situations and the daily routines of six females (aged 7 to 24 months; mean birthweight 3057g, SD 195g) with the preserved speech variant (PSV) of RTT. All videos were recorded by parents and analysed retrospectively after the diagnosis PSV was made. Results From the age of 7 months onwards, we observed two types of vocalizations, appearing intermittently: (1) apparently normal sequences; and (2) atypical (i.e. inhalatory, pressed, or high‐pitched crying‐like) vocalizations. Some participants failed to reach the milestone of canonical babbling. We observed a limited phonological and lexical complexity and a restricted compositional variability. Volubility was reduced during the whole period under observation. Hand stereotypies with simultaneous atypical vocalizations appeared only during the second year of life. Interpretation The intermittent character of normal versus abnormal verbal behaviours might contribute to an early identification of children with a possible genetic mutation, and provides evidence that speech–language functions are abnormal from the very beginning.