Progressive pseudorheumatoid arthropathy of childhood
Progressive pseudorheumatoid arthropathy of childhood (PPAC; MIM 208230) is an autosomal recessively inherited arthropathy due to mutations in the WISP3 gene. The WISP3 gene codes for WNT1-inducible signaling pathway protein 3. PPAC is a progressive disorder with childhood onset. Fatigue, muscle weakness, waddling gait, bowed legs and joint stiffness may be early manifestations. It is eventually characterized by osteoarthritis, joint swelling, stiffness, enlarged epiphyses, joint space narrowing, contractures and pain. Acetabular irregularity, coxa vara and periarticular osteoporosis can also occur. This disorder should be discriminated from juvenile rheumatoid arthritis and spondyloepiphyseal dysplasia tarda