Amyloid-β peptides are the proteolytic fragments of the transmembrane receptor, Amyloid Precursor Protein (APP). As illustrated by Figure 1, an abnormal increase in the enzymatic cleavage of APP by β-secretase in AD results in a misfolded amyloid-β protein that is more susceptible to aggregation extracellularly [5]. The gene discussed is APP; the disease is Alzheimer disease.