In FOP, the mutant receptor causes up-regulation of a transcriptional factor, Id1. Typically, during the first decade of life, sporadic episodes of painful soft tissue swellings (flare-ups) occur, which can transform skeletal muscles, tendons, ligaments, fascia, and aponeuroses into heterotopic bone [3]. This evidence concerns the gene ID1 and fibrodysplasia ossificans progressiva.