Level A protein biomarkers comprise those integrated in the current diagnostic criteria for AD2 that provide an in vivo estimate of the presence of Alzheimer's pathology: CSF markers of amyloid pathology (Aβ42/40 ratio, Aβ4236), markers reflecting tau pathophysiology (phospho-tau species 18137 and 21738) and neuro(axo)nal damage (total-tau) according to the ATN criteria. The gene discussed is MAPT; the disease is amyloidosis.