Indeed, reduced DNA methyltransferase activity as well as decreased cortical levels of Dnmt1, Dnmt3a, and MeCP2 proteins were associated with increased expression of the AD-related genes APP and beta-site APP cleaving enzyme 1 (BACE1) in aged monkeys with AD-like neuropathology [61, 62]. The gene discussed is MECP2; the disease is Alzheimer disease.