A ketogenic diet rescues hippocampal memory defects in a mouse model of Kabuki syndrome

Significance Intellectual disability is a common clinical entity with few therapeutic options. Kabuki syndrome is a genetically determined cause of intellectual disability resulting from mutations in either of two components of the histone machinery, both of which play a role in chromatin opening. Previously, in a mouse model, we showed that agents that favor chromatin opening, such as the histone deacetylase inhibitors (HDACis), can rescue aspects of the phenotype. Here we demonstrate rescue of hippocampal memory defects and deficiency of adult neurogenesis in a mouse model of Kabuki syndrome by imposing a ketogenic diet, a strategy that raises the level of the ketone beta-hydroxybutyrate, an endogenous HDACi. This work suggests that dietary manipulation may be a feasible treatment for Kabuki syndrome. Kabuki syndrome is a Mendelian intellectual disability syndrome caused by mutations in either of two genes (KMT2D and KDM6A) involved in chromatin accessibility. We previously showed that an agent that promotes chromatin opening, the histone deacetylase inhibitor (HDACi) AR-42, ameliorates the deficiency of adult neurogenesis in the granule cell layer of the dentate gyrus and rescues hippocampal memory defects in a mouse model of Kabuki syndrome (Kmt2d+/βGeo). Unlike a drug, a dietary intervention could be quickly transitioned to the clinic. Therefore, we have explored whether treatment with a ketogenic diet could lead to a similar rescue through increased amounts of beta-hydroxybutyrate, an endogenous HDACi. Here, we report that a ketogenic diet in Kmt2d+/βGeo mice modulates H3ac and H3K4me3 in the granule cell layer, with concomitant rescue of both the neurogenesis defect and hippocampal memory abnormalities seen in Kmt2d+/βGeo mice; similar effects on neurogenesis were observed on exogenous administration of beta-hydroxybutyrate. These data suggest that dietary modulation of epigenetic modifications through elevation of beta-hydroxybutyrate may provide a feasible strategy to treat the intellectual disability seen in Kabuki syndrome and related disorders.