HDAC9 and Huntington disease: They were first shown to be protective in a Drosophila melanogaster model [25] and following on from the demonstration that SAHA, a potent HDAC inhibitor, improves HD-related phenotypes in the R6/2 mouse, (Hockly et al., 2003), protective effects of the butyrates in HD mouse models were also reported [22], [23].