Those, include, among others, Loeys–Dietz syndrome (LDS) which is caused by heterozygous loss-of-function (LOF) variants in TGFBR1 (MIM: 190181), TGFBR2 (MIM: 190182), TGFB2 (MIM: 190220) or TGFB3 (MIM: 190230), SMAD2 (MIM: 601366) or SMAD3 (MIM: 603109) and Marfan syndrome (MFS) (MIM: 154700) caused by variants in FBN1, encoding fibrillin 1, the main component of extracellular matrix microfibrils that scaffolds latent TGF-β (Figure 1). Here, SMAD2 is linked to Marfan syndrome.