Type XII collagen

Type XII collagen is a fibril-associated collagen with interrupted triple helices (FACIT). It is located in the interstitial matrix and is a component of human skeletal muscle. Type XII collagen contains special domains, such as the NC3 domain, which carries glycosaminoglycan chains and interacts with matrix proteins such as decorin, COMP, fibromodulin, and tenascin. Col12a−/− mice display skeletal abnormalities, such as shorter and smaller long bones with reduced mechanical strength and altered vertebrae structure, and disorganized and less polarized osteoblasts with disrupted cell–cell interactions. Recessive and dominant mutations in COL12A1 cause a novel EDS/myopathy overlap syndrome in humans and mice. Currently, there are no biomarkers of type XII collagen.