Indeed, PSEN1-mutation-related AD is conceived as a disease of Aβ anabolism while at least some forms of common, sporadic AD (i.e., that linked to APOE4;[8]) are conceived as a disease of Aβ catabolism. Other genes linked to common, sporadic AD (e.g., CR1) appear to act via the immune response and may modulate cerebral amyloidosis in unexpected ways [9]. The gene discussed is PSEN1; the disease is Alzheimer disease.