Habashi et al. reported that AT1R blocker (ARB) losartan reduced blood pressure and inhibited aortic aneurysm formation in Fbn1C1039G/+ mice, but it could not in Fbn1C1039G/+ mice lacking the AngII type 2 receptor gene (Fbn1C1039G/+; AT2−/−). This evidence concerns the gene AGTR1 and aortic aneurysm.