The phenotype of fibrodysplasia ossificans progressiva

The phenotype of fibrodysplasia ossificans progressiva (FOP) includes two defining features: congenital malformation of the great toes and progressive heterotopic ossification in characteristic anatomic patterns. Additional common features include proximal medial tibial osteochondromas, orthotopic fusions of the posterior elements of the cervical spine, broad short femoral necks, and conductive hearing loss. The FOP phenotype supports that the primary molecular pathology involves the bone morphogenetic protein (BMP)-signaling pathway directly or a BMP-interacting pathway.