A diminution of ACE activity in the cerebral cortex and other areas in AD patients was described, being the G4-PRiMA complex the ACE form markedly altered, whereas the ACE monomeric form was almost preserved (Atack et al., 1983; Fishman et al., 1986; Sáez-Valero et al., 1999). The gene discussed is ACE; the disease is Alzheimer disease.