Fibrodysplasia ossificans progressiva

Best Pract Res Clin Rheumatol. 2008 Mar;22(1):191-205. doi: 10.1016/j.berh.2007.11.007.


Fibrodysplasia ossificans progressiva (FOP), a rare and disabling genetic condition of congenital skeletal malformations and progressive heterotopic ossification (HO), is the most catastrophic disorder of HO in humans. Episodic disease flare-ups are precipitated by soft tissue injury, and immobility is cumulative. Recently, a recurrent mutation in activin receptor IA/activin-like kinase 2 (ACVR1/ALK2), a bone morphogenetic protein (BMP) type I receptor, was reported in all sporadic and familial cases of classic FOP, making this one of the most highly specific disease-causing mutations in the human genome. The discovery of the FOP gene establishes a critical milestone in understanding FOP, reveals a highly conserved target for drug development in the transforming growth factor (TGF)-beta/BMP signalling pathway, and compels therapeutic approaches for the development of small molecule signal transduction inhibitors for ACVR1/ALK2. Present management involves early diagnosis, assiduous avoidance of iatrogenic harm, and symptomatic amelioration of painful flare-ups. Effective therapies for FOP, and possibly for other common conditions of HO, may potentially be based on future interventions that block ACVR1/ALK2 signalling.

Publication types

  • Review

MeSH terms

  • Activin Receptors, Type I / genetics
  • Animals
  • Bone Morphogenetic Protein Receptors, Type I / genetics
  • Bone Morphogenetic Proteins / genetics
  • Disease Models, Animal
  • Humans
  • Mutation
  • Myositis Ossificans* / diagnosis
  • Myositis Ossificans* / diagnostic imaging
  • Myositis Ossificans* / genetics
  • Myositis Ossificans* / physiopathology
  • Myositis Ossificans* / therapy
  • Ossification, Heterotopic
  • Radiography
  • Smad Proteins / genetics


  • Bone Morphogenetic Proteins
  • Smad Proteins
  • ACVR1 protein, human
  • Activin Receptors, Type I
  • Bone Morphogenetic Protein Receptors, Type I