MECP2 and Rett syndrome: However, Mecp2 expression has been detected also in glial cells and, although in astrocytes its levels are five-fold lower than in neurons (Rusconi et al., 2008; Ballas et al., 2009; Maezawa et al., 2009; Olson et al., 2014), in vitro and in vivo studies reported that Mecp2 deficiency in astrocytes contributes to the neuropathological manifestations of RTT.