Mutations causing hereditary TAAD affect proteins regulating transforming growth factor-β (TGF-β) signaling, e.g., TGF-β receptors-1 and -2 in Loeys–Dietz syndrome and fibrillin-1 in Marfan syndrome, or components of the SMC contractile apparatus, e.g., SM-α-actin (ACTA2) and myosin heavy chain-11 (MYH11)2,4. The gene discussed is MYH11; the disease is Marfan syndrome.