In the process of normal aging, heightened signaling from ACE1/AGTR1 expression is predominantly countered by ACE1/AGTR2 expression, while the levels of ACE2, MAS1, and LNPEP remain constant, while in the later stages of Alzheimer’s disease, a decline in MAS1 expression emerges. This evidence concerns the gene ACE2 and early-onset autosomal dominant Alzheimer disease.