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Fibrodysplasia ossificans progressiva

Other Names for this Disease
  • FOP
  • Myositis ossificans
  • Myositis ossificans progressiva
  • Progressive myositis ossificans
  • Progressive ossifying myositis
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Fibrodysplasia ossificans progressiva (FOP) is a disorder in which 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) which constrains 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 generally born with abnormally big toes which can be helpful in clarifying the diagnosis.[1]

Trauma to the muscles of an individual with FOP, such as a fall or invasive medical procedure, or a viral illness may trigger episodes of muscle swelling and inflammation (myositis) followed by more rapid bone growth in the injured area.[1]

FOP can be caused by mutations in the ACVR1 gene and is inherited in an autosomal dominant manner.[1]
Last updated: 6/6/2011


  1. Fibrodysplasia ossificans progressiva. Genetics Home Reference (GHR). August 2007; Accessed 4/10/2014.
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Basic Information

  • Genetics Home Reference (GHR) contains information on Fibrodysplasia ossificans progressiva. This website is maintained by the National Library of Medicine.
  • Support guidebooks published by the International Fibrodysplasia Ossificans Progressiva Association contains information about research and treatment options, as well as articles by parents of affected children and adults with FOP offering insights into the condition.
  • The National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS) support research into the causes, treatment, and prevention of arthritis and musculoskeletal and skin diseases, the training of basic and clinical scientists to carry out this research, and the dissemination of information on research progress in these diseases. Click on the link to view information on this topic.
  • The National Organization for Rare Disorders (NORD) is a federation of more than 130 nonprofit voluntary health organizations serving people with rare disorders. Click on the link to view information on this topic.

In Depth Information

  • Medscape Reference provides information on this topic. Click on the link to view this information. You may need to register to view the medical textbook, but registration is free.
  • The Online Mendelian Inheritance in Man (OMIM) is an catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 
  • Orphanet is a European reference portal for information on rare diseases and orphan drugs.  Access to this database is free of charge.
  • PubMed is a searchable database of medical literature and lists journal articles that discuss Fibrodysplasia ossificans progressiva. Click on the link to view a sample search on this topic.

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