Aβ is generated from the proteolysis of amyloid precursor protein (APP) during aging or in subjects with an inherited cause of AD.3 APP is a transmembrane protein whose proteolysis is mediated by α-, β- and γ-secretases that cleave APP at specific sites.3 The amyloidogenic process first involves the cleavage of APP to create a c-terminal fragment (CTF), known as β-CTF, which is subsequently cleaved by a multiprotein γ-secretase complex to produce different lengths of Aβ peptides such as Aβ38, Aβ40 and Aβ42. This evidence concerns the gene APP and Alzheimer disease.