Symptoms

Introduction to FOP
FOP is short for Fibrodysplasia Ossificans Progressiva. The disease is also known as Myositis Ossificans Progressiva; the name was modified in the 1970s to acknowledge the involvement of other soft, or fibrous, tissues in addition to muscle. FOP is a rare genetic disorder in which bone forms in muscles, tendons, ligaments, and other connective tissues. Bridges of extra bone form across the joints in characteristic patterns, progressively restricting movement. FOP is a disease in which the body produces not just too much bone, but an extra skeleton that immobilizes the joints of the body.

Symptoms of FOP
Children with FOP appear normal at birth except for congenital malformations of the great toe. During the first or second decade of life, children form painful fibrous nodules over the neck, back, and shoulders which mature into bone in a process known as heterotopic ossification. FOP then progresses along the trunk and limbs of the body. These lesions slowly replace the body's muscles with normal appearing bone. Any attempt to remove the extra bone results in even more robust bone formation. People who have FOP experience different rates of new bone formation; in some the progress is rapid, while in others it is more gradual. In each case, the exact rate of progression is unpredictable, although there does appear to be a characteristic pattern to the progression. For example, FOP involvement of the upper regions of the body, such as the back and shoulder areas, almost always precedes the development of FOP in the lower portion of the body, i.e. the hips and knees.

Back to Top