In recent years, however, selective HDAC inhibitors have been developed (Wagner et al., 2015) and there is growing evidence that especially HDAC class I inhibitors are effective in suppressing pathogenic mechanisms in mouse models of HD (Thomas et al., 2008; Chiu et al., 2011; Lim et al., 2011; Jia et al., 2012, 2016; Chen et al., 2013; Suelves et al., 2017). Here, HDAC9 is linked to Huntington disease.