The biochemical analysis of Alzheimer’s disease patient brains also suggests the existence of cleaved forms (Wischik et al., 1988; Watanabe et al., 1999; Zilka et al., 2012; Derisbourg et al., 2015) and finally, a mass spectrometric analysis of tau from CSF of Alzheimer’s disease patients identified multiple fragments (Barthélemy et al., 2016a, b; Sato et al., 2018). Here, MAPT is linked to Alzheimer disease.