In an animal model, Ziyi Liu, et al. reported an association between hyperhomocysteinemia (HHcy) and AAA (odds ratio, 7.39) in a meta-analysis, furthermore they observed HHcy aggravates AAA formation via activating adventitial fibroblast NADPH oxidase 4 in angiotensin II–infused male apolipoprotein E deficient mice. The gene discussed is NOX4; the disease is hyperhomocysteinemia.