APP and early-onset autosomal dominant Alzheimer disease: It has been shown that the abnormal processing of APP by β and γ-secretase protease enzymes is a key event in the development of Alzheimer’s disease (AD) neuropathology (Sastre et al., 2003), resulting in an increase in the generation of the 42 amino acid form of Aβ peptide which aggregates to form the insoluble amyloid plaques.