While p-tau181 levels are elevated in AD, show associations with both Aβ and tau PET using agents such as C-PiB (Aβ) and 18F-AV-1451(tau) (previously known as T807) [102–104], suggesting greater specificity for AD pathology than other tau species [105], overall the correlation of tau species measured from blood with CSF tau is relatively weak, potentially limiting the usefulness of currently available tau assays for screening, diagnosis, and monitoring of disease progression. The gene discussed is MAPT; the disease is Alzheimer disease.