COL3A1 and Marfan syndrome: Most common CTD are linked to genes encoding for extracellular matrix proteins in syndromic patterns, like vascular Ehlers–Danlos syndrome with collagen type III alpha 1 chain (COL3A1) gene, Marfan syndrome with fibrillin-1 (FBN1) gene, or Loeys–Dietz syndrome with transforming growth factor beta receptor I and II (TGFBR1 and TGFBR2), or mothers against decapentaplegic homolog 3 (SMAD3) genes.