HTT and juvenile Huntington disease: More recently, similar tau dysregulations have been reported in Huntington's disease (HD) (27, 31, 32, 42, 55, 64, 83, 84) [reviewed in (33, 85)]; a disorder driven by an autosomal dominant pattern of inheritance and caused by a pathological CAG repeat expansion exceeding 35 in exon 1 of the huntingtin (HTT) gene (86) coding for the huntingtin (HTT) protein.