Mecp2 was shown to be critical for GABAergic neuronal function in Rett Syndrome (RTT) as Viaat-Mecp2−/y mice lack Mecp2 in GABAergic neurons, causing RTT-like features that include the development of stereotypes, self-injury, compulsive behavior and progressive motor dysfunction (34). Here, MECP2 is linked to atypical Rett syndrome.