CCN6 and progressive pseudorheumatoid arthropathy of childhood: The PPD is caused by mutation of WISP3 gene on chromosome 6q22.[10]WISP3, expressed in synoviocytes and chondrocytes, belongs to the CCN (cyr61, ctgf, nov) family that encodes proteins for cell growth and differentiation,[11,12] playing a major part in bone growth and cartilage metabolism.