HDAC9 and thoracic aortic aneurysm: Bellenguez et al. discovered that expression of histone deacetylase-9 was upregulated in different VSMC types in people with a thoracic aortic aneurysm (Bellenguez et al., 2012). Rho GTPase activating protein-18 was found by Liu and colleagues to protect against formation of thoracic aortic aneurysms by inhibiting the synthetic and proinflammatory phenotypes of smooth muscle cells (Liu et al., 2017).