In AD, amyloid-β (Aβ) accumulation leads to a chronic stimulation of the immune system which initiates a vicious circle: Cytokines such as interleukin 1-β, IL-6, and tumor necrosis factor-α stimulate the synthesis of β-amyloid precursor protein and Aβ peptides [55]. The gene discussed is TNF; the disease is Alzheimer disease.