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). Here, ARHGAP18 is linked to thoracic aortic aneurysm.