To confirm the involvement of astrocyte Kir4.1 deficit in neuronal hyperexcitability in FXS, we induced Kir4.1 deletion specifically in hippocampal astrocytes by viral delivery of Cre-GFP under the GFAP promoter into the hippocampus of Kir4.1fl/fl male mice (P15–17; Supplementary Fig. 11). The gene discussed is GFAP; the disease is fragile X syndrome.