AAA is a progressive disease characterized by aortic wall atherosclerosis, in which vascular smooth muscle cells (VSMCs) and infiltrating monocytes/macrophages are activated to release a variety of factors, including matrix metalloproteinases, angiotensin II, tumor necrosis factor (TNF)-α, interleukin-1β, interleukin-6, and interferon-γ, consequently generating a chronic inflammatory state. The gene discussed is TNF; the disease is triple-A syndrome.