The phosphorylation sites in the normal brain and AD brain are shown in Figure 2A. The levels of phosphorylation of tau at Ser199, Ser202/Thr205, and Ser422 were comparable in healthy controls and Braak stage I-IV AD patients, but increased in Braak stage V/VI in the isocortex and transentorhinal cortex. Here, MAPT is linked to Alzheimer disease.