Assays have been developed to detect blood tau p-tau181 (Mielke et al., 2018; Karikari et al., 2020), and plasma levels of p-tau181 have been reported to be significantly increased in AD, particularly in symptomatic stages, detecting AD with good accuracy (Mielke et al., 2018; Janelidze et al., 2020; Karikari et al., 2020). Here, MAPT is linked to Alzheimer disease.