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]. The gene discussed is HTT; the disease is early-onset autosomal dominant Alzheimer disease.