Progressive pseudorheumatoid dysplasia

Progressive pseudorheumatoid dysplasia, also called progressive pseudorheumatoid arthropathy of childhood, is a disorder of bone and cartilage that affects many joints. It leads to stiff joints, short stature and widening of the ends of the finger, toe and other long bones. Symptoms usually begin between ages three and six, with an abnormal walking pattern, weakness and fatigue and stiffness in the fingers and knees, and over time fingers may stay bent while the finger and knee joints enlarge and the hips hurt. Because it resembles juvenile rheumatoid arthritis, it can at first be misdiagnosed; the diagnosis rests on molecular genetic testing or characteristic skeletal findings on radiographs. It is inherited in an autosomal recessive pattern through changes in the WISP3 (CCN6) gene, which helps maintain cartilage. Treatment is supportive, with anti-inflammatory drugs, therapy and sometimes surgery, and life span is not severely affected. It is extremely rare but thought to be more common in Turkey and the Middle East.