MECP2 and Rett syndrome: Numerous conditional knockout mice have revealed the importance of MeCP2 function in different cell populations in the brain as well as the etiology of RTT symptoms (Chen et al., 2001; Gemelli et al., 2006; Fyffe et al., 2008; Samaco et al., 2009; Chao et al., 2010; Ito-Ishida et al., 2015; Meng et al., 2016; Zhang et al., 2014; Wang et al., 2014; Goffin et al., 2014; Ward et al., 2011; Adachi et al., 2009; Guy et al., 2001; Su et al., 2015; Johnson et al., 2017).