Fibrodysplasia ossificans progessiva (FOP) is an ultra-rare disease caused by a mutation, almost always identical, in the ACVR1 gene. This gene encodes a type I bone morphogenetic protein (BMP) receptor. The clinical picture includes outbreaks of heterotopic ossification in the muscles, leading to true ankylosis.
- Among the many therapeutic avenues considered, the specific blocking of the receptor ligand seemed very attractive;
- however, two independent groups of researchers have just demonstrated that the use of these monoclonal antibodies is deleterious, at least in animals;
- the FOP model animals used for this purpose tended to develop more heterotopic ossification, the opposite of what was expected.