Familial thoracic aortic aneurysm and dissection (FTAAD), caused by the pathogenic Myh11 K1256del variant, is characterized by impaired aortic contractility; however, how reduced contractility predisposes the aorta to dissection remains incompletely understood. The gene discussed is MYH11; the disease is familial thoracic aortic aneurysm and aortic dissection.