While the predefined single cut-off for the diagnosis of AD was 50.0 pg/mL, based on our stratified ROC analyses, the cut-off was 45.9 pg/dL for differentiating amyloid-negative from amyloid-positive individuals and 63.9 pg/mL for differentiating tau pathology limited to the transentorhinal region from extensive tau pathology in amyloid-positive individuals. The gene discussed is MAPT; the disease is Alzheimer disease.