Rett syndrome: a preliminary analysis of stereotypy, stress, and negative affect.

•Rett syndrome is a neurodevelopmental disorder primarily affecting females.•Stereotypic hand movements are one of the core diagnostic criteria for RTT.•Signs of negative affect were more likely to occur during high versus low stress conditions for females with Rett syndrome.•Hand stereotypy of females with Rett syndrome did not differ across conditions.•The results suggest that hand stereotypy may not be a valid indicator of stress or arousal in females with Rett syndrome.