2005), and plays a fundamental role in the mechanisms of early progression of AD (Selkoe 2004; Gandy 2005). Despite an abundance of information concerning AD pathophysiology, the initial events that trigger Aβ plaque formation are poorly understood. Aβ originates from a large type 1 transmembrane protein, known as the amyloid precursor protein (APP) (Selkoe 2001). The gene discussed is APP; the disease is Alzheimer disease.