What is FOP?


What is Fibrodysplasia ossificans progressiva (FOP)?

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:

Clinical Characteristics of FOP:

  • Malformation of the great toes is visible at birth
  • Flare-ups that worsen the connection 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 a clinical trial is 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 Stone Man Disease, a documentary about FOP. 








Malformation of the great toes



Flare-ups in the back of a young child



Make a Difference

Donate Connect Fundraise

Already a Member? Sign In

Sign Up for FOP Connection, Our Monthly eNewsletter