Fibrodysplasia ossificans progressiva (FOP) is characterized by the gradual replacement of muscle tissue and connective tissue (such as tendons and ligaments) by bone, restricting movement. This process generally becomes noticeable in early childhood, starting with the neck and shoulders and proceeding down the body and into the limbs.
The formation of extra-skeletal bone causes progressive loss of mobility as the joints become affected. Speaking and eating may also become difficult as the mouth becomes affected. Over time, people with FOP may become malnourished because of the inability to eat. They may also develop breathing difficulties as a result of extra bone formation around the rib cage that restricts expansion of the lungs.
Any trauma to the muscles of an individual with FOP (a fall or an invasive medical procedure) may trigger episodes of muscle swelling and inflammation followed by more rapid ossification in the injured area. Flare-ups may also be caused by viral illnesses such as the flu.
People with FOP are generally born with malformed big toes. This abnormality of the big toes is a characteristic feature that helps to distinguish this disorder from other bone and muscle problems. Affected individuals may also have short thumbs and other skeletal abnormalities.
Last updated: 4/10/2014
We hope this information is helpful. We strongly recommend you discuss this information with your doctor. If you still have questions, please