For cerebrospinal fluid and plasma biomarkers of tau pathology, the differential diagnostic value for distinguishing AD from bvFTD is less well established, and as with amyloid-β markers, they become abnormal relatively early in the disease course, which lowers their specificity.102,103 Hence, a full AD-like fluid biomarker profile with abnormalities in both amyloid-β and phosphorylated tau supports a level II diagnosis of possible bvAD. This evidence concerns the gene MAPT and Alzheimer disease.