APP and familial Alzheimer disease: Elevated amyloid β production can be a consequence of altered proteolytic digestion of amyloid precursor protein in response to a variety of stresses (e.g., inflammation, oxidative stress, and lower levels of oxygen, 2-oxoglutarate, or iron) or mutations in genes responsible for familial Alzheimer’s disease (e.g., APP, PSN1, and PSN2) [6,21,22,23].