While familial-AD has been associated with mutations in the genes coding for the amyloid precursor protein (APP) and the presenilins (PSEN1 and PSEN2) proteins, the only genetic factor extensively replicated for sporadic AD is the apolipoprotein E-ε4 (APOE-ε4) allele [4]–[6], which is present in ca. 60% of the cases [1], [7]–[9]. The gene discussed is APOE; the disease is Alzheimer disease.