APP and Alzheimer disease: Studies in the murine model AD susceptible mice, known as 5XFAD mice that express human APP and presenilin (PSEN1) transgenes with a total of five AD-linked mutations, have shown accelerated accumulation of β-amyloid plaques and exacerbated neuroinflammation even though their adaptive immune system is genetically ablated (Rag2−/−/Il2rγ−/−-5XFAD mice).