In AS and MR, non-fibrillar collagens (collagen types 6, 12, 14, and 18) and matricellular proteins (POSTN and TGFBI) were more abundant, as were ECM glycoproteins (TNXB and FBN1), proteoglycans (VCAN and HAPLN1), and three members of the SLRP (small leucine-rich proteoglycan) class, namely, biglycan (BGN), decorin (DCN), and asporin (ASPN). Here, BGN is linked to aortic valve stenosis.