FOP is an extremely rare disease. Approximately one in two million people worldwide are affected by this disorder.  More than 800 individuals with FOP have been identified worldwide. There is no ethical, racial, gender, geographic, predilection to FOP.

Fibrodysplasia ossificans progressiva is caused by mutations in the ACVR1 gene. For the majority of people with FOP, the disorder results from a new (spontaneous) mutation in the gene. In instances of a spontaneous new mutation, there is no history of the disorder within their family.

All individuals with FOP have congenital malformations of the great toes. Some the will have short malformed thumbs, as well. Usually, during early childhood, individuals may experience episodes of swellings involving the soft tissues of the body. These swellings may be mistaken for tumors, eventually resolve, but often leave heterotopic bone in the affected areas (e.g. tendons, ligaments, skeletal muscle tissue, and connective tissue). Episodes may occur spontaneously, but more often follow a ‘triggering’ event such as trauma to the soft tissue, muscular stretching, injections directly into muscle tissue, careless dental work, viral infections, fatigue or falls. A person may go months or even years without an episode of new bone formation.

    The progressive formation of bone causes the affected joints to become stiff and eventually locked into place, making movements impossible. If the jaw is involved, individuals may have difficulties eating. Bone development in the middle ear can lead to hearing impairment. Eventually, individuals may have difficulties walking and severe restrictions in their movements. Pain can occur in affected areas from the compression of nearby nerves. Progressive spinal and chest wall deformities may affect normal breathing and put affected individuals at risk for pneumonia and congestive heart failure. Eventually, complete immobilization can occur.

Misdiagnosis is common in individuals with FOP. However, the proper diagnosis can easily be made through physical examination.  

    A diagnosis can be confirmed by sequencing of the ACVR1 gene. Biopsies must not be performed because the local trauma caused by a biopsy can lead to new abnormal bone growth.

Currently, there are no definitive treatments for FOP. Treatment is symptomatic. Various medications have been used to manage symptoms in individuals with FOP. A brief course of high-dose corticosteroids (such as prednisone), started within the first 24 hours of an episode, can reduce the inflammation and the swelling of the tissues during an episode.  Corticosteroid treatment should generally be reserved for episodes that affect the major joints, jaw or the area beneath the lower jaw (submandibular area). Nonsteroidal anti-inflammatory drugs (NSAIDs) are often used between episodes

Other medications have been used to treat individuals FOP. Such medications include muscle relaxants, mast cell inhibitors, Cox-2 inhibitors, and aminobisphosphonates. Ultimately, specific decisions regarding which medications should be used will be up to individuals and their physicians or medical team. A detailed explanation of the current treatment options and guidelines are available from the International Fibrodysplasia Ossificans Progressiva Association (www.ifopa.org).

Occupational therapy can benefit for some individuals with FOP. Specific devices including special shoes or braces can assist in walking and weight-bearing.

Surgery to remove heterotopic and extra-skeletal bone is not recommended due to the individual’s high health risk and the potential for growth of a new bone (which may be painful, as well).

By the second decade of life, individuals may be wheelchair-bound, However, the rate of progression of the disorder varies greatly.

The discovery of the causative gene in 2006 opened new avenues to research for effective treatments for FOP. As of early 2016, a clinical trial is underway to explore a potential drug therapy for individuals with FOP.

Fibrodysplasia ossificans progressiva can be accelerated through trauma. As a result, the individuals with this disorder should try to be gentle at all times and try to prevent falls. In general, individuals should avoid deep tissue trauma (which includes intramuscular injections).

Genetic counseling is recommended for individuals and families affected by FOP. Psychosocial support for the entire family is also beneficial.

Fibrodysplasia Ossificans Progressiva. Genetic Home Reference website. http://ghr.nlm.nih.gov/condition/fibrodysplasia-ossificans-progressiva  Updated August 2007. Accessed October 30, 2015.

Fibrodysplasia Ossificans Progressiva. Online Mendelian Inheritance in Man (OMIM) website. http://omim.org/entry/135100. Updated March 2015. Accessed October 30, 2015.

Fibrodysplasia Ossificans Progressiva. National Organization for Rare Disorders website. https://rarediseases.org/rare-diseases/fibrodysplasia-ossificans-progressiva/. Updated 2014. Accessed October 30, 2015.

Kaplan FS, Pignolo RJ, Shore EM. From mysteries to medicines: drug development for fibrodysplasia ossificans progressive. Expert Opin Drugs. 2013;1(8):637-649.

Kaplan F, Pignolo R, Shore E. Fibrodysplasia Ossificans Progressiva. Orphanet website. http://www.orpha.net/consor/cgi-bin/OC_Exp.php?Lng=GB&Expert=337.0 Updated March 2011. Accessed October 30, 2015.

Pignolo RJ, Shore EM, Kaplan FS. Fibrodysplasia ossificans progressiva: diagnosis, management, and therapeutic horizons. Pediatr Endocrinol Rev. 2013;10 Suppl 2:437-438.

Pignolo RJ, Shore EM, Kaplan FS. Fibrodysplasia ossificans progressiva: clinical and genetic aspects. Orphanet J Rare Dis. 2011;6:80. http://www.ojrd.com/content/6/1/80/abstract  Accessed October 30, 2015.