The most clinically significant syndromes include Marfan syndrome (with a mutation in the fibrillin-1 gene (FBN1)), Loeys–Dietz syndrome (with a mutation in transforming growth factor β 2 and 3 (TGFB2, TGFB3), transforming growth factor β type receptor 1 and 2 (TGFBR1, TGFBR2) and SMAD2 and SMAD3 genes). The gene discussed is SMAD2; the disease is Marfan syndrome.