LAUSR

ABSTRACT The Forkhead Box G1 (FOXG1) gene encodes a transcription factor with an essential role in mammalian telencephalon development. FOXG1‐related disorders, caused by deletions, intragenic mutations or duplications, are usually associated with severe intellectual disability, autistic features, and, in 87% of subjects, epileptiform manifestations. In a subset of patients with FoxG1 mutations, seizures remain intractable, prompting the need for novel therapeutic options. To address this issue, we took advantage of a haploinsufficient animal model, the FoxG1+/− mouse. In vivo electrophysiological analyses of FoxG1+/− mice detected hippocampal hyperexcitability, which turned into overt seizures upon delivery of the proconvulsant kainic acid, as confirmed by behavioral observations. These alterations were associated with decreased expression of the chloride transporter KCC2. Next, we tested whether a triheptanoin‐based anaplerotic diet could have an impact on the pathological phenotype of FoxG1+/− mice. This manipulation abated altered neural activity and normalized enhanced susceptibility to proconvulsant‐induced seizures, in addition to rescuing altered expression of KCC2 and increasing the levels of the GABA transporter vGAT. In conclusion, our data show that FoxG1 haploinsufficiency causes dysfunction of hippocampal circuits and increases the susceptibility to a proconvulsant insult, and that these alterations are rescued by triheptanoin dietary treatment. HighlightsFoxG1+/− mice show hippocampal hyperexcitability.FoxG1+/− mice are highly vulnerable to proconvulsant‐induced seizures.FoxG1+/− mice have decreased expression of the chloride transporter KCC2.Triheptanoin rescues functional and molecular abnormalities of FoxG1+/− mice.