Three different profiles: early socio-communicative capacities in typical Rett syndrome, the preserved speech variant and normal development.

BACKGROUND AND AIMS This is the first study aiming to compare pre-diagnostic socio-communicative development of a female with typical Rett syndrome (RTT), a female with the preserved speech variant of RTT (PSV) and a control toddler. METHODS We analysed 1275 min of family videos at the participants' age between 9 and 24 months and used the Inventory of Potential Communicative Acts (IPCA) to delineate their repertoires of communicative forms and functions. RESULTS The results revealed different profiles for the three different conditions. The repertoire of communicative gestures and (pre)linguistic vocalizations was most comprehensive in the control toddler, followed by the female with PSV and the female with RTT. CONCLUSION These findings contribute to the growing knowledge about early developmental abnormalities in RTT. In order to define distinctive profiles for typical and atypical RTT and evaluate their specificity, a larger body of evidence is needed.