Thus, genetic ablation of the MeCP2 gene leads to defects in synaptic development and maturation, and a complete loss of MeCP2 function leads to brain development disorders like Rett Syndrome (RTT), which is a severe autism spectrum disorder (Amir et al., 1999; Chen et al., 2001; Moretti et al., 2006). Here, MECP2 is linked to Rett syndrome.