Fibrodysplasia ossificans progressiva

Fibrodysplasia ossificans progressiva (FOP) is an extremely rare and disabl ing genetic disorder of connective tissue. The condition is characterized b y congenital malformation of the great toes and by progressive heterotopic ossification of the tendons, ligaments, fasciae, and striated muscles. Fibr odysplasia ossificans progressiva occurs sporadically and is transmitted as a dominant trait with variable expression and complete penetrance. Reprodu ctive fitness is low. There are fewer than 150 known patients with the diso rder in the United States. A point prevalence of one affected patient in ev ery 2 million of population has been observed. There is no sexual, racial, or ethnic predilection. The disease presents in early life; its course is u navoidably progressive. Most patients are confined to a wheelchair by the t hird decade of life and often succumb to pulmonary complications in the 5th /6th decade of life. At present there is no effective prevention or treatme nt. The recent discovery of overproduction of bone morphogenetic protein-4 in lesional cells and lymphocytic cells of affected patients provides a clu e to both the underlying pathophysiology and potential therapy The FOE gene has recently been mapped to human chromosome 4q 27-31.