Tauopathies are further defined by the isoform abundance in their inclusions; specifically, AD aggregates contain both 3R and 4R tau (Goedert et al., 1989a; Jakes et al., 1991), PiD is mostly 3R tau (De Silva et al., 2003), and tau inclusions in CBD are mostly 4R tau (Sergeant et al., 1999). This evidence concerns the gene MAPT and Alzheimer disease.