FOP is caused due to a genetic mutation in the ACVR1 gene. This gene is involved in growth and development of bones. The mutation allows them to grow unchecked. The gene can be inherited from one parent, but in most cases of FOP there could be a new mutation in a person with no family history of the disease.

It is an autosomal dominant disorder which means a parent with FOP has a 50 percent chance of passing it on to their child.

• Movement can become severely restricted as bone grows into joints.
• The spine can become deformed or fused.
• Limited mobility may cause balance and coordination problems that can lead to injury
• due to falling. Even a minor injury can cause more inflammation and bone growth.
• Bone growth in the chest can restrict breathing, increasing the risk of respiratory
• infection. Any viral illness can trigger a flare-up.
• Limited movement of the jaw can make it hard to eat, which can lead to malnutrition
• and weight loss. Talking can also be difficult.
• About half of people with FOP experience hearing impairment.
• Poor blood flow can lead to pooling of the blood in the arms or legs, causing visible
• swelling

• malformations of the big toe
• spontaneous flare-ups of inflammation or soft tissue swelling
• increased flare-ups after injury, viral illness, or immunisations
• difficulty moving
• frequent injury due to falling

There is currently no treatment that can slow or stop disease progression. FOP is chronic and there is no cure. Treatment can help ease symptoms and improve quality of life. Some of these are:

• corticosteroids to reduce pain and swelling during flare-ups
• non-steroidal anti-inflammatory drugs (NSAIDs) between flare-ups
• assistive devices such as braces or special shoes to help with walking
• occupational therapy

There is nothing that can make the new bones go away. Surgery would result in more bone growth. An important part of the treatment plan has to do with what to avoid. A biopsy, for example, can cause rapid bone growth to the area. Intramuscular injections, such as most immunizations, can also cause problems. Dental work must be performed with great caution, avoiding injections and stretching of the jaw. Blunt trauma or injury due to falling can cause a flare-up. Any physical activities that increase these risks should be avoided.

FOP can be dangerous during pregnancy, which can increase the chances of flare-ups and complications for both mother and baby.

The rate of progression is different for each patient and is difficult to predict. Some people go months or even years without a flare-up.

FOP can become severely disabling. Most people with FOP will need a wheelchair by the time they reach their late 20s. The median lifespan for people with FOP is 40 years.

Some organisations which raise awareness for FOP are:

• Ifopa.org
• Fopindia.org
• Rarediseases.org

If there is a known case of FOP in the family, it is absolutely essential for closest relatives like siblings, uncles, aunts and cousins to test for carrier status.

If a woman with a carrier status is pregnant, prenatal test is essential to determine if the fetus has the disease mutation.