SMAD3 and Loeys-Dietz syndrome: TGFBR1/2 and SMAD2/3 encode proteins involved in TGF-β signaling and mutations in these genes cause Loeys-Dietz syndrome (LDS) in patients (TGFBR1; LDS1; MIM 609192, TGFBR2; LDS2; MIM 61068, SMAD2; LDS6; MIM 619656, SMAD3; LDS3 (AOS); MIM 613795).