Although concentrations of aggrecan and decorin have not previously been assessed in the blood of children with juvenile idiopathic arthritis, the concentrations of their degradation products, i.e., aggrecan neoepitopes (ARGS) [20], dermatan sulfates (DS) [22], and keratan sulfates (KS) [23], have been studied. This evidence concerns the gene DCN and juvenile idiopathic arthritis.