Neurons from a mouse model of Rett syndrome (lacking Mecp2) or derived from induced pluripotent stem cells (iPSCs) of patients with Rett syndrome exhibit a more depolarizing GABA signaling26 that could be rescued by either KCC2 exogenous expression65 or pharmacological drugs enhancing KCC2 activity97. Here, SLC12A5 is linked to atypical Rett syndrome.