At an early stage of aneurysm development (after 2 weeks of co-administration of BAPN and Ang II), serum SM22α levels were markedly decreased compared with saline group (P<0.001), and significantly elevated in mice with ruptured aneurysm after 3 weeks administration (P<0.001), suggesting that it may be associated with SM22α released into the blood stream during the rupture process of aneurysm. The gene discussed is AGT; the disease is aneurysm.