HTT and Alzheimer disease: These so-called amyloid diseases include Alzheimer’s disease (AD), Huntington’s disease (HD), Parkinson’s disease (PD), transmissible spongiform encephalopathies (or prion diseases), and type II diabetes (T2D), which are mediated by the aggregation of the amyloid-β peptide (Aβ) and tau protein, huntingtin (HTT), α-synuclein (α-syn), prion protein (PrP), and islet amyloid polypeptide (IAPP, also known as amylin), respectively [1].