HTT and Huntington disease: Moreover, these studies have been extended in both mice and non-human primates, in which administration of siRNAs selective for Huntingtin are effective in delaying neurodegeneration, and may also have some efficacy in preventing the cognitive decline observed in Huntington’s disease (Lombardi et al., 2009; Pfister et al., 2009; Zhang et al., 2009; McBride et al., 2011; Stiles et al., 2012).