Fibrodysplasia Ossificans Progressiva

Fibrodysplasia Ossificans Progressiva is a rare genetic disorder in which connective tissue and muscle tissue are gradually ossified. Extra-skeletal bone formation causes progressive loss of mobility. The process starts in early childhood and often forms a pattern starting with the neck and shoulders and proceeding down the body into the limbs. Ossification happens spontaneously or after trauma. The prevalence is approximately 1:2.000.000 and no ethnic, racial or geographic predisposition has been described.

Trauma is an important factor in heterotopic ossification in FOP, therefore (intramuscular) injections, biopsies, and other invasive procedure are strongly advised against.

A mutation in activin receptor IA/ activin-like kinase 2 (ACVR1/ALK2), a bone morphogenetic protein (BMP) type I receptor, is the cause of all sporadic and familial cases of classic FOP.

Last modified
17 June 2021



ORPHA:337 Fibrodysplasia ossificans progressiva

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FOP Stichting Nederland

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General Medical Guideline
Fibrodysplasia ossificans progressiva (FOP) is characterized by disabling heterotopic ossification (HO) from episodic flare-ups.
Congenital bilateral hallux valgus with associated absence or fusion of the interphalangeal joint is classic diagnostic feature from birth in more than about 98% of...
Torticollis is a common presenting feature of FOP (in about 80%), the head is tilted to one side and there are painful swelling in the...
Flare-ups are swellings around muscles and connective tissue. A flare-up occurs after injury, viral infection, overuse or spontaneous. Usually progresses from the axial regions to...
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