Fibrodysplasia ossificans progressiva (FOP)
Written by Ada’s Medical Knowledge Team
What is fibrodysplasia ossificans progressiva (FOP)?
Fibrodysplasia ossificans progressiva (FOP) is a very rare genetic condition. It's also called stone man syndrome. This condition is of genetic origin and present from birth, but is often only diagnosed during adolescence. FOP causes bone to form in the muscles and tendons. The bony lumps can occur without a cause or after an injury such as bruises or muscle strains. This causes pain and limits movement. The diagnosis can be confirmed by the symptoms and genetic testing. There's no cure for this condition but there are medicines that can help with some of the symptoms.
What are risk factors for FOP?
The condition most often correlates with a specific gene changing. This altered gene may then be passed down from a parent with the condition to their children who will most likely get the condition. FOP is very rare with only about 800 known cases worldwide. The bony lumps can occur after an injury such as bruises or muscle strains.
What are FOP symptoms?
Affected people are usually born with abnormal great toes. During the first 10 years of life, most children with FOP develop painful lumps across the body. The swellings may happen after injuries such as bruises or muscle strains. They may resolve without treatment or cause bone to grow. This can happen in muscles, ligaments, and tendons. Hearing loss and hair loss may also be present. Problems breathing and chewing are possible. There may also be trouble with body movements.
How is FOP diagnosed?
Diagnosis is based on the history of symptoms and a physical exam. Imaging scans and genetic testing may be helpful. A biopsy, or collection of samples from the affected tissue, should be avoided.
How is FOP treated?
There is no known cure for this condition. However, there are medicines that can help with the symptoms. This usually includes painkillers and medicines that calm the immune system. This can help with joint pain and stiffness.
Can FOP be prevented?
There's no proven way to prevent FOP. This is because the cause of the condition usually is an altered gene. However, it's possible to prevent some of the swelling by avoiding injuries such as bruises or muscle strains.
What is the outlook for FOP?
The outlook of this condition is poor. Most FOP patients are bedridden by the time they are in their 30s, and they usually die around 40 years of age. The most common causes of death are respiratory complications.