Frequently Asked Questions
Fibrodysplasia ossificans progressiva, or FOP, is an ultra-rare genetic condition that affects around 1 in a million people. It is one of the most disabling conditions known to medicine.
FOP causes the soft connective tissue of the body to turn into new bone. When that occurs over or near joints, or within a muscle, it restricts the person’s movements. This new bone, or ossification, can mean that the sufferer is no longer able to move the joint. Once movement has been lost in a part of the body, it is not possible to remove the new bone as that can aggravate the FOP and trigger further bone growth.
Most cases of FOP are new. It is caused by a fault in the ACVR1 gene and this gene mutation usually happens at conception: it is an accident of nature.
Where one parent has FOP, the likelihood of passing the condition on to a child is 50%.
People with FOP appear normal at birth, except for the tell-tale malformed, turned-in big toes. The big toes may be shortened and curl under. The person may also have shorter or turned in thumbs. The toes, combined with unexplained swellings across the body, can be an indicator of FOP.
The swellings are known as flare-ups. These are painful lumps that can appear anywhere across the body. They can be red and inflamed. They can last from a few weeks to a few months, causing inconvenience and discomfort, and be excruciatingly painful for the patient. A flare-up can appear spontaneously or after an incident. As the flare-up subsides, new bone growth may have occurred.
FOP is a variable and progressive illness. Whilst a fall, injury or virus can trigger an FOP flare-up, a flare-up can also appear spontaneously and without warning.
Some people with FOP suffer from flare-ups from very early on in life, even as young as birth, whilst other people may not have any symptoms or restrictions until their 20s or beyond. FOP can cause people to have long periods of flare-ups whilst at other times the FOP can be quiet for months or even years before something triggers it again. People can experience more than one flare-up at a time. They can also suffer one flare-up after another for a period of time; this is known as a flare cycle.
If you are concerned that you or someone else may have FOP, you should see your GP and request a referral to the Centre for Metabolic Bone Disease at the Royal National Orthopaedic Hospital, Stanmore. They have an experienced FOP medical team who will be able to advise and assess your symptoms. They will carry out investigations and/or request a genetic blood test to confirm the diagnosis.
Due to the rarity of FOP, many medical practitioners will never have heard of the condition. Under no circumstances should the lumps be biopsied before confirmation, as this can aggravate the FOP and cause irreversible damage.
A knock or fall can trigger FOP and cause a flare-up. Any impact into the muscle can trigger FOP activity. Precautions need to be taken to reduce the likelihood of a person with FOP encountering unnecessary risks.
Intramuscular injections (IM) can cause FOP activity so should be avoided if at all possible. Where medically necessary, specialist advice should be sought prior to any administration of injections. Injections should be administered by skilled and experienced practitioners and not medical students.
Vaccinations and childhood immunisations can aggravate FOP but the benefits may outweigh the risks. Advice should be sought from an experienced FOP medical specialist before carrying out any immunisations. The NHS childhood vaccination programme can be delayed until the diagnosis is confirmed and the precautionary steps have been advised and agreed. Most vaccines can be administered sub-cutaneously (under the skin) to reduce the risk of aggravating the FOP. Some vaccinations can be omitted, under advice from your GP or FOP specialist.
Muscle fatigue can trigger a flare-up, as can viruses, with flu being of significant risk.
Surgery carries an extremely high risk and should be avoided unless absolutely necessary. Where surgery is required, expert advice should be sought and appropriate steps taken to minimise the risk of any FOP complications. In the event of an emergency, protection of life should be taken as if FOP is not a consideration.
Dental treatment can be extremely invasive and carries the risk of triggering extra bone formation in the jaw, resulting in restrictions in the jaw movement. Seek advice from a Special Care Dentist.
All injections and vaccinations should be administered sub-cutaneously wherever possible. IM injections should be avoided. No vaccinations should be given if a person is suspected to be in a state of active flare.
- People with FOP need to take precautions against flu, as the illness can cause complications for them.
- People with FOP can often develop scoliosis which causes further complications.
- Invasive dental treatments carry a higher risk for people with FOP, so excellent preventative dental hygiene is vital.
- Hearing is affected by FOP, with around 50% of people reporting some or complete loss.
- People with FOP can suffer from mental health issues as they come to terms with living with the condition.
At present there is no known treatment or cure for FOP. There are a number of medications and therapies people use that may have some efficacy. Seek qualified medical guidance before making any decisions.
- Prednisolone: it is generally accepted that there may be benefits to a person with FOP taking a short course of the steroid prednisolone to reduce inflammation. It is not suitable for regular use, nor for all flare-ups.
- Ibuprofen: there is some anecdotal evidence that ibuprofen can help to reduce inflammation after a minor impact.
- Imatantib: whilst there is no definitive evidence that imatinib prevents flare-ups, there have been some reports that it can help to break flare-cycles in children.
- Montelukast (Singulair): this may help control or reduce unwanted inflammation in the lungs. Some people take this daily in the hope it might have a beneficial/potential effect on future flare-ups. There have been no formal studies to assess the drug’s effectiveness for FOP.
There is much research being carried out around the world into a treatment and a cure for FOP. There is real hope for people who are suffering from this disease.
FOP Friends fundraises to support the FOP research team at the University of Oxford and works closely with its researchers.
In July 2019, the International Clinic Council for FOP (a consortium of 26 medical professionals and consultants) released updated medical guidelines for the management of the condition, and treatment considerations for patients with FOP.
For more information, read the ICC Medical Guidelines 2021.
All patients, their carers, their primary medical physician/s, and their local hospital should have a copy. These guidelines can be obtained, free of charge, by contacting FOP Friends or the IFOPA.
The information in this leaflet is given in good faith and is based on sources believed to be accurate at the time of printing. It should not be considered a substitute for qualified medical advice.
Patients or carers who suspect a diagnosis of FOP should consult their GP or their hospital before making any decisions or drawing any conclusions.
We do not accept any legal liability for the content of this leaflet or for the content of external sources.
Reviewed by: Dr Richard Keen MB BS BSc PhD FRCP