Fibrodysplasia Ossificans Progressiva (FOP)

Also known as Stone Man Syndrome, it's a very rare genetic condition in which the soft tissue in the body, such as muscles or connective tissue (tendons and ligaments) ossifies when injured. In other words, it turns into bone tissue when damaged and subsequently repaired. A common consequence of this disease presents itself when injuries cause the body joints to become frozen in place, inhibiting  articulation movement and rendering the patient paralyzed. 

Symptoms:

Being a genetic disease it has some phenotypic markers that could be identifiable in children who have FOP. These include deformed big toes, notable lumps in minor joints and absence of body minor joints. The bone grows from the top and makes its way down. Children with FOP may present bone growth starting in the neck and shoulders and progressing towards their arms, chest, abdominal area and legs. Despite this, there is no specific order of bone appearance since its synthesis is due to injury-caused flare-ups. After these injuries, the resulting bone expresses independently from the skeletal structure, generating tumor-like lumps that may fuse with the normal skeleton. The only tissues that don't participate in this process are found in diaphragm, tongue and in ocular, smooth and cardiac muscles. Since its such a rare disease, the diagnosis may be mistaken for cancer or fibrosis which leads to surgical procedures (biopsies) which cause more bone growth.

Causes: 

This disease is caused by a mutation in the gene ACVR1. This causes this gene to express itself after fetus formation when it should usually suppress itself in this moment of growth. After an injury occurs in the soft tissues, the immune response sends lymphocytes with an excess of bone morphogenetic protein 4 which causes the damaged cells to express an enzyme for bone repair. This causes endothelial cells to become mesenchymal  stem cells (multipotent stormal cells that may become bone, cartilage, or fat cells) and then bone cells. There have been approximately 700 confirmed cases in history across the world.

Treatment:

There is no known cure for FOP. Every risky activity should be avoided by the patient such as surgery or any activity that may cause falling. Research including squalamine protein found in sharks and kinase inhibitors are being studied to block the ACVR1  effects in the organism of the patient, but there is no approved treatment for the disease.


Reference: http://en.wikipedia.org/wiki/Fibrodysplasia_ossificans_progressiva