Occurrence of familial Alzheimer’s disease (FAD) represents the minority (5%–10%) of all AD cases. Familial early onset Alzheimer’s disease (EOAD) can be characterized by the Mendelian inheritance pattern; however, EOAD patients have also been reported without any family history (termed “sporadic EOAD”). Three genes are considered the main risk factors for EOAD: amyloid precursor protein (APP), presenilin 1 (PSEN1), and presenilin 2 (PSEN2; Figure 1). Mutations in these genes might result in alteration of amyloid beta (Abeta) production (both Abeta 40 and Abeta 42), leading to apoptosis of the neurons and dementia.6–9 Figure 2 presents a timeline of AD onset according to age.5,10
