It is noteworthy that several molecular mechanisms including Angiotensin II (Ang II)29, myeloperxidase30, NF-κB31, cyclooxygenase-2 (COX-2) and microsomal prostaglandin E2 synthase-1 (mPGES-1)32, were associated with the adverse outcome after aneurysm rupture, but the detailed mechanisms of leukocyte in cerebral aneurysm remain obscure. The gene discussed is PTGS2; the disease is brain aneurysm.