Individuals with autism spectrum disorders (ASD) who have an identifiable single-gene neurodevelopmental disorder (NDD), such as fragile X syndrome (FXS, FMR1), Smith-Magenis syndrome (SMS, RAI1), or 2q23.1 deletion syndrome (del 2q23.1, MBD5) share phenotypic features, including a high prevalence of sleep disturbance.
Haploinsufficiency of RAI1 results in developmental delay, mental retardation, sleep disturbance, self-abusive behaviors, and most features commonly seen in SMS.