In familial nonsyndromic thoracic aortic aneurysms and dissections (FTAAD), while most causative genes remain unidentified, around 20% of cases are associated with mutations in genes that support the contractile apparatus of smooth muscle cells, including smooth muscle actin and myosin (ACTA2 and MYH11, respectively). The gene discussed is MYH11; the disease is familial thoracic aortic aneurysm and aortic dissection.