RG2833 (RGFP109) is a potent and selective brain-penetrant HDAC inhibitor with IC50 of 60 nM and 50 nM for HDAC1 and HDAC3, respectively. It upregulates frataxin mRNA and protein levels dose-dependently in cultures of unstimulated peripheral blood mononuclear cells (PBMC) obtained from FRDA patients. In vivo it corrects frataxin deficiency and increases histone acetylation in the brain and heart of KIKI mice without acute toxicity signs.