One commonly used model, 3xTg-AD, also includes human transgenic microtubule associated protein tau (MAPT) with the P301L mutation in addition to mutant human APP and PS1. All of these models overexpress Aβ in the CNS and develop diffuse Aβ plaques starting as early as 2-3 months of age (19). The gene discussed is APP; the disease is Alzheimer disease.