HTT and Alzheimer disease: β-Amyloid, α-synuclein, huntingtin protein, prion protein, tau, TAR-DNA-binding protein 43 kDa, and fused-in sarcoma protein are the most common proteins that contribute to Alzheimer’s disease (AD), Parkinson’s disease (PD), Huntington’s disease (HD), transmissible spongiform encephalopathies, tauopathies, and amyotrophic lateral sclerosis (ALS), respectively [1,2,3,4,5].