HTT and Huntington disease: Examples of this in the CNS include AAV-mediated RNAi targeting HTT mRNA for HD,14–16,25,26 ataxin-1 for spinocerebellar ataxia type 1,27 and ataxin-3 for spinocerebellar ataxia type 3.28 However, even with artificial miRNA scaffolds, there is a possibility that the endogenous miRNA biogenesis pathway is overharnessed.