Based on studies in mice, both isoforms of MECP2, MECP2_e1 and MECP2_e2, bind to transcription factor FOXG1, with MECP2_e2 binding more strongly. Increased expression of Mecp2_e2 may contribute to neuronal death and this function of Mecp2_e2 may be inhibited by FoxG1 (Dastidar et al. 2012). FOXG1 mutations can, in addition to MECP2 and CDKL5 mutations, also cause Rett syndrome (Ariani et al. 2008).