The observation that mutations in WISP3/CCN6 lead to progressive pseudorheumatoid dysplasia (PPRD) and polyarticular juvenile idiopathic arthritis, diseases that are associated with cartilage growth plate defects and/or loss of adult articular cartilage indicates that this CCN-protein might be related to the preservation of cartilage integrity [19,20]. Here, CCN6 is linked to progressive pseudorheumatoid arthropathy of childhood.