PSP is associated with 4-repeat (4R) tau inclusions1,3; FTD is characterized by 3-repeat (3R)-only, 4R-only, or mixed (3R and 4R) tau inclusions or TAR DNA-binding protein 43 aggregates4; and AD is characterized by extracellular amyloid plaques and neurofibrillary tangles (NFTs) composed of hyperphosphorylated tau (mixed 3R and 4R tau inclusions)5,6. This evidence concerns the gene MAPT and supranuclear palsy, progressive, 1.