The contribution of tau to HD pathogenesis involves, but is not limited to, the presence of aggregated tau inclusions in the brain of HD patients [7, 9, 11, 17, 23, 25, 26, 31, 38], the influence of MAPT haplotype in cognition of HD patients (patients with the H2 haplotype are more severely cognitively impaired than those with the H1 haplotype) [38], the amelioration of behavioral abnormalities of HD mice by genetic ablation of Mapt [11], and the mHTT-mediated alterations in tau splicing isoform expression [11] and tau hyperphosphorylation [6, 13]. This evidence concerns the gene MAPT and Huntington disease.