In addition, three familial AD-associated mutations were introduced into the endogenous mouse App locus: the Swedish (NL) mutation, which elevates total Aβ production [13]; the Beyreuther/Iberian (F) mutation, which increases the Aβ42/Aβ40 ratio [14, 15]; and the Arctic (G) mutation, which promotes Aβ aggregation [16, 17]. This evidence concerns the gene APP and Alzheimer disease.