Cross Linked C-Telopeptide Of Type II Collagen (CTXII)

The myriad substitutions for glycine residues in the two chains of type I collagen that cause osteogenesis imperfecta illustrate the critical role of the glycine residue in establishing structural integrity. The helix of type I collagen is formed from two a1 chains and one a2 chain; the amino acid sequences of a1 and a2 chains differ slightly from one another. The structure of type II collagen is similar to that of type I, but the helix is formed from three identical a1 chains. As indicated,substitutions of different amino acids at different positions produce either a mild, moderate, or severe form of skeletal diseases. Similar glycine substitutions in type II collagen produce skeletal disorders referred to as chondrodysplasias,but it is more difficult to relate the manifestations of disease to the mutations. The circulating levels of the CTX-II with relation to disease onset and structural damage of cartilage in a rodent model of collagen-induced arthritis (CIA).