Table 2.

Summary of proteins influenced by changes due to SNPs in their respective genes.

System	Protein
Structural	Collagen I (20, 27, 28)
	Collagen IX (20, 29–33)
	Collagen XI (4, 33, 34)
	Aggrecan (24, 43–46)
Structural support	Carbohydrate sulfotransferase (47)
	Vitamin D receptor (12, 20, 48–51)
Cytokines	Interleukin-1a (35, 36)
	Interleukin-6 (13, 36, 37)
Extracellular matrix-degrading enzymes	Matrix metalloproteinase (MMP)-1 (58)
	MMP-2 (38, 39)
	MMP-3 (12, 40)
	MMP-9 (11)
	MMP-14 (41)
	A disintegrin and metalloproteinase with thrombospondin motif (ADAMTS)-4 (42)
	ADAMTS-5 (34)
Apoptotic factors	TNF (tumor necrosis factor)-related apoptosis-inducing ligand (TRAIL) (53)
	Death receptor 4 (25)
	Caspase-9 (1, 52)
	Parkin (56)
Growth factors	Growth differentiation factor 5 (52, 54)
	Vascular endothelial growth factor (55)
Pain mediators	Cyclooxygenase 2 (34)
	Catechol-O-methyltransferase (57)