FOP is caused by activating mutations (mostly, the highly recurrent c.617G>A/p.R206H missense gain-of-function mutation) in the ACVR1/ALK2 gene, that encodes the type 1 activin A receptor and leads to aberrant activation of the bone morphogenetic protein pathway and new neo-ligand activity of the activin A receptor [3]. This evidence concerns the gene ACVR1 and fibrodysplasia ossificans progressiva.