The primary aggregation-prone proteins involved include amyloid-beta (Aβ) and tau in Alzheimer’s disease (AD), α-synuclein (α-Syn) in Parkinson’s disease (PD), and huntingtin (HTT) in Huntington’s disease (HD) (Jucker and Walker, 2018). The gene discussed is HTT; the disease is early-onset autosomal dominant Alzheimer disease.