Taken together and based on the A/T/N classification scheme for BBMs of brain amyloid pathology [51], the above evidence and recent findings [11,12] support the working hypothesis that plasma Aβ42/40 is an early biomarker for brain amyloid dysmetabolism and amyloid plaque formation that precedes or signals neuronal death, phospho-tau tangle formation, and phospho-tau release into the plasma and CSF [52,53]. The gene discussed is MAPT; the disease is amyloidosis.