Tau proteins have been detected in the blood using sensitive methods (Zetterberg et al., 2013; Chiu et al., 2017; Tatebe et al., 2017; Fossati et al., 2019; Lue et al., 2019), and our study suggests that blood products containing modified tau proteins might have a potential role in modulating the development of AD pathologies in the brain of elderly people in which the blood–brain barrier permeability is increased with aging. The gene discussed is MAPT; the disease is Alzheimer disease.