APP and Alzheimer disease: Aβ was first isolated by Glenner and Wong in 1984.74 Aβ may provide a strategy for diagnostic testing for AD and for understanding its pathogenesis.74 APP was first cloned and sequenced in 1987; APP consists of 695 amino acid residues and a glycosylated receptor located on the cell surface.75,76 Aβ is composed of 39–43 residues derived from multiple proteolytic cleavages of APP.