ACTA2 and Marfan syndrome: The best characterized genes include FBN1 [Marfan syndrome (MFS)], TGFBR1 and TGFBR2 [Loeys-Dietz syndrome (LDS)], SMAD3 [aneurysm-osteoarthritis syndrome (AOS)], and ACTA2 [Aortic and Cerebral Aneurysm (ACA)].