An abnormal upregulation in the spontaneous turnover of pyramidal neuron dendritic spines has been observed across several mouse models of autism including the MECP2-duplication mouse (Chow et al., 2009; Cruz-Martín et al., 2010; Jiang et al., 2013; Isshiki et al., 2014; Gdalyahu et al., 2015; Ash et al., 2018), while mouse models of Rett syndrome exhibited decreased dendritic spine motility (Landi et al., 2011), suggestive of an abnormal balance between synaptic stability and plasticity. Here, MECP2 is linked to Rett syndrome.