In a study involving caregivers of 364 patients with RTT with confirmed MECP2 mutations, registered in the International Rett Syndrome Phenotype Database (InterRett), who completed the validated Sleep Disturbance Scale for Children (SDSC), findings indicated that over 80% of RTT patients experienced night wakings, and nearly half of this group experienced night wakings often. Here, MECP2 is linked to atypical Rett syndrome.