Proteolytically cleaved tau fragments are also present in human tauopathy brain, some of which may have a causal role in tau pathophysiology (Wischik et al., 1988; Zilka et al., 2006; Wray et al., 2008; Amadoro et al., 2010; Gu et al., 2020). Here, MAPT is linked to tauopathy.