Diseases and Conditions Feature

The Rarest Medical Conditions in the World


Fibrodysplasia ossificans progressiva, “Stone Man Syndrome”

Fibrodysplasia ossificans progressiva, more commonly known as “Stone Man Syndrome” or FOP is a progressive genetic disorder that targets the body’s connective tissues. This disease is so rare that only one person in two million are believed to be affected by this disease with a total of 700 cases worldwide and almost 300 in the United States specifically. In those individuals with FOP, when any of the fibrous tissues such as a ligament, muscle, or tendon become damaged, they turn into bone via a process known as ossification. In no other disease or disorder does a part of one the body’s systems turn into something completely different.

One main indicator of FOP at birth is a malformed big toe. Unfortunately, to date there has been no medical breakthroughs in the treatment of FOP. Moreover, when treatment is attempted to get rid of the bone that is formed, more bone seems to be produced in this area. The cause behind FOP is a defective ACVR1 gene. This gene’s main purpose is to allow the body to convert cartilage into bone when we are children; however, due to a strange mutation of this gene it can also cause connective tissues to turn into bone and for joints to be fused together.