CCN6 and progressive pseudorheumatoid arthropathy of childhood: Wisp3 mutations have been demonstrated in most patients of an autosomal recessive hereditary cartilage metabolic disorder, spondyloepiphyseal dysplasia tarda with progressive arthropathy (SEDT-PA), or progressive pseudorheumatoid dysplasia (PPD), which characterized by deformation and limitation of most large and small joints clinically, and continuous degeneration and loss of articular cartilage pathologically [7–11].