In this context, the decrease in Aβ42, and concomitant increase in Aβ42/Aβ40 and Aβ42/Aβ38 ratios and T-tau and P-tau levels is commonly referred to as the Alzheimer profile or signature, as it offers the possibility of detecting AD in its early stages [35,42,57,58]. The gene discussed is MAPT; the disease is Alzheimer disease.