Overexpression of an Osteogenic Morphogen in Fibrodysplasia Ossificans Progressiva

The human skeleton is a complex organ system consisting of more than 200 articulated bones of various shapes and sizes. During embryogenesis, the skeleton develops from undifferentiated mesenchyme according to a genetic plan that controls its precise temporal and spatial formation. Postnatally, the initiation of osteogenesis is normally restricted to the regeneration of bone at fracture sites. Heterotopic ossification results from an alteration in the normal regulation of osteogenesis, leading to ectopic bone formation. Fibrodysplasia ossificans progressiva, first described in 1692, is the most extensive disorder of heterotopic osteogenesis in humans and results in the postnatal formation of ectopic bone. . . .