As amyloidosis and tauopathy are the neuropathological hallmarks of AD, the positivity of in vivo biomarkers reflecting amyloidosis and tauopathy, i.e., reduced amyloid-β42/β40 ratio (Aβ42/Aβ40) and increased levels of phosphorylated tau (p-Tau) in cerebrospinal fluid (CSF), allows to define AD independently from the clinical stage. Here, MAPT is linked to Alzheimer disease.