The pathogenesis of certain neurodegenerative and autoimmune diseases is characterized by the misfolding and aggregation of proteins with prion-like properties, such as β-amyloid (Aβ) and tau in Alzheimer’s disease (AD), alpha-synuclein (α-syn) in Parkinson’s disease, TDP-43 and SOD1 in amyotrophic lateral sclerosis, and IAPP in type 2 diabetes1–5. The gene discussed is MAPT; the disease is Alzheimer disease.