The potential therapeutic value of reducing HTT expression in the brains of individuals afflicted with HD or other polyQ disorders is well recognized [37], and antisense oligonucleotides that target Htt sequences common to mutant and normal alleles have been shown to reduce overall production of Htt mRNA and protein in brain tissue when delivered into the cerebrospinal fluid of HD-afflicted mice by transient infusion [18]. This evidence concerns the gene HTT and Huntington disease.