In the current study, we compared discordant (CSF+/PET− and CSF−/PET+) with concordant-negative (CSF−/PET−) and concordant-positive (CSF+/PET+) patients across four diagnostic groups (subjective cognitive decline (SCD), mild cognitive impairment (MCI), AD dementia, and non-AD dementia) in terms of (i) baseline demographics, cognition, APOE ε4 status, and CSF tau levels, (ii) longitudinal cognitive trajectories, and (iii) changes in clinical diagnosis. This evidence concerns the gene MAPT and Schnyder corneal dystrophy.