MMP-9 expression in patients with CAA-related intracerebral hemorrhage (CAA-ICH) was significantly higher than in those without hemorrhage, while TIMP-3 expression was lower in patients with CAA-ICH; these findings suggest that an imbalance between MMP-9 and TIMP-3 may increase the risk of hemorrhage. This evidence concerns the gene MMP9 and intracerebral hemorrhage.