MECP2 and atypical Rett syndrome: CCC targeting has been particularly effective in clinical trials with bumetanide used to reduce intracellular Cl– in autism spectrum disorders (ASDs) (Ben-Ari, 2017) such as in Rett syndrome (RTT), a disorder caused by a mutation in the transcriptional repressor Methyl CpG binding protein 2 (MeCP2) gene (Chahrour et al., 2008).