Recently it has been shown that there is an increase in the 4R:3R tau isoform ratio, with nuclear rod-like tau deposits (TNRs) in Huntington’s disease post-mortem brain samples as well as an attenuated motor phenotype in mutant HTT transgenic mice with genetic tau reduction (Fernández-Nogales et al., 2014). Here, MAPT is linked to juvenile Huntington disease.