APP and Alzheimer disease: Second-generation App knock-in mouse models of AD harboring Swedish, Beyreuther/Iberian, and Arctic mutations (AppNL−G−F/NL−G−F; APP-KI) exhibit increased Aβ(1–42) production, Aβ pathology, neuroinflammation, and age-dependent cognitive impairment without alterations in the expression levels of APP or other fragments [22].