MAPT and semantic dementia: Higuchi and colleagues have reported that AD and several other diseases (tangle predominant dementia, Down syndrome, Guam-Parkinson-dementia complex, atypical CJD with NFTs, Niemann-Pick disease type C, and FTDP-17 with R406W MAPT mutation) have morphologically similar neurofibrillary structures composed of 95 % PHFs and minimal straight filaments (SFs) [51].