Alterations in dendrites, spines, glutamatergic neurotransmission, and GABAergic neurotransmission are observed in Rett syndrome (RTT) and CDKL5 disorder (CDD) (Schematic generated with the help of Biorender). Arrows indicate deviations from wild-type (WT) controls. (Blue et al., 1999, 2011 [28,29]; Durand et al., 2012 [30]; Johnston et al., 2014 [31]; Lo et al., 2016 [32]; Banerjee et al., 2016 [33]; Della Sala et al., 2016 [24]; Tang et al., 2016, 2019 [34,35]; Okuda et al., 2017 [36]; Tramarin et al., 2018 [37]; Dong et al., 2018 [38]; Zhu and Xiong, 2019 [22]; Ren et al., 2019 [23]; Yennawar et al., 2019 [39]).