Studies in AD patients (Braak and Braak, 1995) as well as in vitro (Frost et al., 2009) and in vivo (Clavaguera et al., 2009), have shown that the spread of tau accumulation in tauopathy is related to the prion-like properties of tau (Mudher et al., 2017; Duyckaerts et al., 2019). The gene discussed is MAPT; the disease is Alzheimer disease.