Several lines of evidence support that mutations in amyloid precursor protein (APP) and presenilin 1 (PSEN1) and 2 (PSEN2) genes lead to the development of the disease and production of toxic Aβ, especially in patients with early-onset autosomal dominant familial Alzheimer’s disease (FAD) [7,8]. This evidence concerns the gene PSEN1 and familial Alzheimer disease.