Fibrodysplasia ossificans progressiva (FOP) is a genetic disorder that causes the development of bone where other muscle or other soft tissue is normally present. The tissues affected include muscle, tendons, ligaments, and other connective tissue. This bone formation is often painful and limits the range of motion in the affected area. The disorder is sometimes called “stone man syndrome” because bone growth over joints will severely limit movement, eventually imprisoning the body in bone.
While the first formation of extra bone may not occur until after age 10, a common symptom of children born with FOP is the presence of big toe deformities. The initial symptoms of FOP occur early in life and include swelling and inflammation of the shoulders and back, which eventually resolves but leaves behind new bone. Young children with FOP often do not crawl because of limited mobility in their joints. The symptoms of pain and loss of mobility become worse as the affected individuals ages, although the timeframe for new bone formation is different for each patient. By late stages of FOP, the skeleton becomes fused into one piece by the growth of new bone. Movement becomes impossible because joints are replaced by solid bone.
FOP is caused by a change (mutation) on a specific gene inherited from both parents. Because the disease is so rare, the symptoms may be misdiagnosed as more common diseases, such as myositis ossificans traumatic or other inflammatory diseases or movement disorders. Without proper diagnosis, affected individuals who undergo surgery are at risk of worsening their symptoms.
There is currently no known cures for FOP, and treatments focus on reducing the symptoms. Surgical removal of the excess bone often causes more bone formation, worsening the prognosis for the patient. Medications may be used to decrease inflammation and pain. If you are suffering from FOP, talk to your doctor about the most current treatment options.