HDAC9 and psychiatric disorder: Many brain disorders are associated with imbalances in protein acetylation levels and transcriptional dysfunction.76 Histone deacetylase (HDAC) inhibitors represent a promising therapeutic option to correct these deficiencies, and numerous studies using butyrate, the most potent of the SCFA HDAC inhibitors,9,77 demonstrate the medicinal potential of butyrate in the intervention of neurodegenerative diseases and psychiatric disorders.26,64,76,78–85