Fibrodysplasia ossificans progressiva (FOP) is a disorder in which muscle tissue and connective tissue such as tendons and ligaments are graduallyreplaced by bone (ossified), forming bone outside the skeleton (extra-skeletal or heterotopic bone) that constrains movement. This process generally becomes noticeable in early childhood, starting withthe neck and shoulders and proceeding down the body and into the limbs.
Extra-skeletal bone formation causes progressive loss of mobility as the joints become affected. Inability to fully open themouth may cause difficulty in speaking and eating. Over time, people with this disorder may experience malnutrition due to their eating problems. They may also have breathing difficulties as a result ofextra bone formation around the rib cage that restricts expansion of the lungs.
Any trauma to the muscles of an individual with fibrodysplasia ossificans progressiva, such as a fall or invasivemedical procedures, may trigger episodes of muscle swelling and inflammation (myositis) followed by more rapid ossification in the injured area. Flare-ups may also be caused by viral illnesses such asinfluenza.
People with fibrodysplasia ossificans progressiva are generally born with malformed big toes. This abnormality of the big toes is a characteristic feature that helps to distinguish thisdisorder from other bone and muscle problems. Affected individuals may also have short thumbs and other skeletal abnormalities.
How common is fibrodysplasia ossificans progressiva?
Fibrodysplasiaossificans progressiva is a very rare disorder, believed to occur in approximately 1 in 2 million people worldwide. Several hundred cases have been reported.
What genes are related to fibrodysplasiaossificans progressiva?
Mutations in the ACVR1 gene cause fibrodysplasia ossificans progressiva.
The ACVR1 gene provides instructions for producing a member of a protein family called bone morphogenetic...