• Tau phosphorylation in HD brain tissue: S396, S404, T205, S199 (32) and S202 (AT8 antibody) (42, 43). • ↑ p-tau in cortex and striatum of HD patients (27, 32). • Detection of hyper-p-tau S202 and T205 in healthy fetal neural allografts in two HD patient recipients (42). • ↑ hyper-p-tau in the brains of R6/2 (56, 64), zQ175 (64) and 140CAG knock-in (56) mouse models of HD. Here, MAPT is linked to Huntington disease.