These may also affect TGF-β signaling, like ACTA2 mutations, occurring in 16 % of patients with familial thoracic aortic aneurysm and in sporadic thoracic aortic aneurysms and dissections associated with medial degeneration, focal medial smooth muscle cell hyperplasia and proliferation, and stenotic arteries in the vaso-vasorum (Guo et al. 2007; Morisaki et al. 2009; Renard et al. 2013). This evidence concerns the gene ACTA2 and thoracic aortic aneurysm.