High-performing assays for plasma amyloid-beta 40 (Aβ40), amyloid-beta 42 (Aβ42), phosphorylated-tau 181 (P-tau181), neurofilament light chain (NfL), and glial fibrillary acidic protein (GFAP) can detect relatively well AD and neurodegeneration-related pathological changes. The gene discussed is MAPT; the disease is Alzheimer disease.