What is FOP?

What is Fibrodysplasia ossificans progressiva (FOP)?

Malformation of the great toes

One of the rarest, most disabling genetic conditions known to medicine, FOP causes bone to form in muscles, tendons, ligaments and other connective tissues. Bridges of extra bone develop across joints, progressively restricting movement and forming a second skeleton that imprisons the body in bone. There are no other known examples in medicine of one normal organ system turning into another.

Demographics of FOP:

  • Rare, progressive genetic disorder that has an estimated prevalence of 1 per 735,000 to 1 per 2 million births (Baujat et al. Orphanet Journal of Rare Diseases (2017) 12:123)
  • No ethnic, racial, or gender patterns
  • 900 confirmed cases worldwide
  • 285 known cases in the United States
  • Mahmoud.jpg
    Flare ups on the back of a young child
    View poster of FOP demographics worldwide here

Clinical Characteristics of FOP:

  • Malformation of the great toes is visible at birth
  • Flare-ups that worsen the condition occur spontaneously or following physical trauma such as: childhood immunizations, falls, surgery, biopsy or viral illnesses
  • Rogue bone growth progressively restricts movement
  • Often misdiagnosed as cancer
  • The exact rate of progression is unpredictable, although there appears to be a pattern to the progression (e.g., upper body in childhood and lower body in adolescence)
  • No treatment exists, but seven clinical trials are currently underway

Read A Few Hundred People Turned to Bone article from The Atlantic for a detailed overview of FOP and the research around the disease.

Watch our awareness video about FOP:

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