The phosphorylated Tau (p-Tau) present in the cerebrospinal fluid (CSF) and blood plasma are being measured for p-Tau181, 217, 231, and 235 in plasma and CSF and used for the staging of AD and Down’s syndrome (DS) [3,4,5,6,7,8] (Table 1). The gene discussed is MAPT; the disease is Down syndrome.