BGN and intervertebral disk degenerative disorder: The biochemical changes of the major components of the human NP (type II collagen and the proteoglycan aggrecan), and also minor components, including collagen (types III, V, VI, IX-XII and XIV) and small proteoglycans (lumican, biglycan, decorin and fibromodulin), during disc degeneration have been well documented[9, 52].