HDAC4 and Huntington disease: The impact of genetic knock-out or reduction of several Hdac genes (Hdac3, Hdac4, Hdac6, Hdac7) has previously been investigated in the R6/2 exon 1 mouse model of HD and in HdhQ150 knock-in mice with the goal of understanding which HDAC targets mediated the beneficial effects of broad-acting HDAC inhibitors (Benn et al., 2009; Bobrowska et al., 2011; Moumné et al., 2012; Mielcarek et al., 2013).