MECP2 and atypical Rett syndrome: Moreover, MECP2 is mutated in Rett syndrome (RTT), a neurodevelopmental disorder characterized by intellectual disability and some features related to autism spectrum-disorders (Amir et al., 1999) and both RTT mouse and human neuronal models show that, MECP2 deficient neurons have deficits in dendritic complexity and synaptic connectivity, as well as altered neuronal excitability (Jentarra et al., 2010; Marchetto et al., 2010; Xu et al., 2014).