MAPT and Alzheimer disease: To date, both Aβ protein, which produces plaques, and phosphorylated tau, a key component of NFTs, have long been recognized as the two pathological hallmarks of AD [19]; however, both of these have some limitations in terms of their utility in early diagnosis, such as the sensitivity of instruments required to measure these proteins in the blood and CSF, and due to the peripheral production of Aβ, there is significant overlap between diagnostic groups [20].