HTT and early-onset autosomal dominant Alzheimer disease: These include tau protein and amyloid-beta peptide (Aβ) in Alzheimer’s disease (AD) [3], huntingtin (Htt) in Huntington’s disease (HD) [4], α-synuclein in Parkinson’s disease (PD) [5], islet amyloid polypeptide (IAPP), or amylin in type 2 diabetes mellitus (T2DM) [6], TDP-43 in amyotrophic lateral sclerosis (ALS) [7] and frontotemporal dementia (FTD) [7], and prion protein (PrP) in transmissible spongiform encephalopathies or TSEs [8].