By evaluating skeletal abnormalities in 201 healthy children with JIA aged 0–16 years, authors showed decreased serum cartilage oligomeric matrix protein (COMP) and bone alkaline phosphatase (BAP) concentrations, which, respectively, reflect chondrocytes turnover and osteoblastic activity, and increased serum metalloproteinase-3 (MMP-3), which represents a predictor of joint destruction and disease activity. This evidence concerns the gene COMP and juvenile idiopathic arthritis.