PSEN1 and Alzheimer disease: The 5xFAD mouse is a transgenic model of AD carrying five mutations associated with early onset familial Alzheimer's disease (FAD): the K670N/M671L (Swedish), I716V (Florida), and V717I (London) mutations in human amyloid precursor protein (APP) and the M146L and L286V mutations in human presenilin-1 (PS1) [19–22].