Examples of peptides or proteins forming fibrillar deposits in the central nervous system include amyloid-β (Aβ) in Alzheimer’s disease (AD), α-synuclein (α-syn) in Parkinson’s disease (PD), tau in frontotemporal lobar degeneration (FTD), and TDP-43 in amyotrophic lateral sclerosis (ALS) [1,2]. The gene discussed is MAPT; the disease is Alzheimer disease.