Another study for analyzing the effect of age compared the double transgenic (TG) mice expressing a chimeric mouse/human amyloid precursor protein (APP) and a mutant human presenilin 1 (PSEN1), both APP/PSEN1 mutations ensured an early-onset of D, and C57BL/6 wild-type (WT) mice, and the results unveiled the potential of targeting the gut microbiota in AD animals [52]. This evidence concerns the gene APP and Alzheimer disease.