Fibrodysplasia Ossificans Progressiva
Also known as: FOP, Myositis Ossificans Progressiva, MOP
Fibrodysplasia Ossificans Progressiva (FOP) is an extremely rare genetic disorder characterized by the abnormal development of bone in areas of the body where bone is not normally present (heterotopic ossification), such as muscles, tendons, ligaments, and other connective tissues. This progressive ossification leads to limited movement, disability, and a shortened lifespan. It is caused by a mutation in the ACVR1 gene.
Imagine your body is like a superhero, but instead of healing normally, it accidentally turns muscles and soft parts into bone. This makes it hard to move and can cause problems. Doctors are working hard to find ways to help!
Signs & Symptoms
- Malformation of the great toes (hallux valgus or short great toes)
- Progressive heterotopic ossification (bone formation outside the skeleton)
- Swelling, inflammation, and pain preceding ossification
- Limited range of motion
- Scoliosis
- Breathing difficulties due to chest wall restriction
- Feeding difficulties
Treatment Options
Corticosteroids (e.g., Prednisone)
MODERATELY EFFECTIVE (to reduce inflammation during flare-ups)Nonsteroidal Anti-inflammatory Drugs (NSAIDs)
MODERATELY EFFECTIVE (to manage pain and inflammation)Physical Therapy
SUPPORTIVE (to maintain mobility and prevent contractures, but must be done very carefully to avoid triggering new bone formation)Supportive Care
SUPPORTIVE (managing pain, preventing injuries, and providing assistive devices)Palovarotene
MODERATELY EFFECTIVE (Reduces new heterotopic ossification) Approved 2023Diagnosis
- Clinical examination (presence of malformed great toes and progressive heterotopic ossification)
- Genetic testing (ACVR1 gene mutation analysis)
- Radiographs (X-rays) to visualize heterotopic bone formation
- CT scans to assess the extent of ossification
History
FOP was first described in the late 17th century, but its genetic basis was not discovered until 2006 when the ACVR1 gene was identified as the causative gene. This discovery has led to significant advances in understanding the pathogenesis of FOP and developing potential therapies.
Recent Breakthroughs
FDA Approves Palovarotene for FOP
Palovarotene, a retinoic acid receptor gamma (RARγ) agonist, received FDA approval for reducing the volume of new heterotopic ossification (HO) in adults and children aged 8 years and older with FOP.