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Fibrodysplasia ossificans progressiva


Other Names for this Disease

  • FOP
  • Myositis ossificans
  • Myositis ossificans progressiva
  • Progressive myositis ossificans
  • Progressive ossifying myositis
See Disclaimer regarding information on this site. Some links on this page may take you to organizations outside of the National Institutes of Health.

Overview

What is fibrodysplasia ossificans progressiva?

What are the symptoms of fibrodysplasia ossificans progressiva?

How is fibrodysplasia ossificans progressiva inherited?

How might fibrodysplasia ossificans progressiva be treated?

What is fibrodysplasia ossificans progressiva?

Fibrodysplasia ossificans progressiva (FOP) is a disorder in which skeletal muscle and connective tissue, such as tendons and ligaments, are gradually replaced by bone (ossified). This condition leads to bone formation outside the skeleton (extra-skeletal or heterotopic bone) that restricts movement. This process generally becomes noticeable in early childhood, starting with the neck and shoulders and moving down the body and into the limbs. People with FOP are born with abnormal big toes (hallux valgus) which can be helpful in making the diagnosis. Trauma, such as a fall or invasive medical procedure, or a viral illness may trigger episodes of muscle swelling and inflammation (myositis). These flareups lasts for several days to months and often result in permanent bone growth in the injured area. FOP almost always caused by a mutation at the same place in the ACVR1 gene and is inherited in an autosomal dominant manner. This condition occurs in about 1 in 1,600,000 newborns and about 800 people worldwide are known to have FOP.[1][2]
Last updated: 6/5/2014

What are the symptoms of fibrodysplasia ossificans progressiva?

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.[1]

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.[1]

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.[1]

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.[1]
Last updated: 4/10/2014

How is fibrodysplasia ossificans progressiva inherited?

Fibrodysplasia ossificans progressiva is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder. [1]

Most cases of fibrodysplasia ossificans progressiva result from new mutations in the gene. These cases occur in people with no history of the disorder in their family. In only a small number of cases, an affected person has inherited the mutation from one affected parent. [1]
Last updated: 6/6/2011

How might fibrodysplasia ossificans progressiva be treated?

There is currently no definitive treatment.  However, a brief course of high-dose corticosteroids, such as Prednisone, started within the first 24 hours of a flare-up, may help reduce the intense inflammation and tissue swelling seen in the early stages of fibrodysplasia ossificans progressiva.  Other medications, such as muscle relaxants, mast cell inhibitors, and aminobisphosphonates, if appropriate, should be closely monitored by a physician.  Surgery to remove heterotopic and extra-skeletal bone is risky and can potentially cause painful new bone growth. [3]
Last updated: 3/21/2011

References
  1. Fibrodysplasia ossificans progressiva. Genetics Home Reference (GHR). August 2007; http://ghr.nlm.nih.gov/condition/fibrodysplasia-ossificans-progressiva.
  2. FOP Fact Sheet. International Fibrodysplasia Ossificans Progressiva Association. http://www.ifopa.org/what-is-fop/overview.html. Accessed 6/5/2014.
  3. Pignolo R, Kaplan F. Pediatric Fibrodysplasia Ossificans Progressiva. E-medicine. July 30, 2009; http://emedicine.medscape.com/article/1007104-overview. Accessed 3/17/2011.


Other Names for this Disease
  • FOP
  • Myositis ossificans
  • Myositis ossificans progressiva
  • Progressive myositis ossificans
  • Progressive ossifying myositis
See Disclaimer regarding information on this site. Some links on this page may take you to organizations outside of the National Institutes of Health.