Fibrodysplasia ossificans progressiva (FOP)

Fibrodysplasia ossificans progressiva (FOP)

By A. Zheng duo 

Fibrodysplasia ossificans progressiva, a.k.a FOP or Stoneman Syndrome, is a rare genetic condition affecting one out of two million people where you body's soft tissues, such as your muscles, ligaments, tendons and tissues ossifies, or turns into bone (heterotopic ossification). A genetic mutation of the body's repair mechanism causes this disease-which of course is a bad thing because now, even minor injuries, such as a scrape to the knee, can cause more bone growth. Why? Well, it's because the body "repairs" the injured area with more bone. What's stranger is that the disease can start to progress because of nothing. Also, the additional bone limits mobility in the neck, joints, and more. It is an autosomal dominant condition, which means that a child has a 50% chance of inheriting this genetic disease if one of his/her parents is affected and the other unaffected. Onset of the disease is usually before age 10, and affected patients live until 40 years old if properly managed, but life expectancy can decrease due to late diagnosis, trauma and infections. Unfortunately, patients are usually bedridden by age 20.

Causes

This rare disease is caused by a mutation on the chromosome 2q23-24 in the gene ACVR1,which gives instructions for the formation of the protein "bone morphogenetic protein type-1 receptor" which gives out instructions for the formation of bone. In order not to produce to many signals, an inhibitor gene called FKBP1A binds tightly to the ACVR1 gene, essentially shutting it off. However, the mutated ACVR1 gene produces a bone morphogenetic protein with a different shape of receptor. This makes the FKBP1A inhibitor gene bind less tightly to the receptor, so the receptor is still partially on, and therefore still capable of sending signals out. 

Signs and Symptoms

For unknown reasons, children born with FOP have deformed big toes pointing at a strange angle, sometimes with one less joint, or with a lump at the minor joint. The first flare-up usually occurs before age 10. Additional bones start forming at the head, moves down and ends at the feet. However, injuries, such as the scrape to the knee like I mentioned earlier, can change the order. As the disease progresses, it gets harder to breathe (as your lungs can't fully expand due to bone growths on the rib cage), eat (as the extra bone locks your jaw shut), keep your balance, speak, sit and walk. It sometimes leads to curves in the spine. Chances of infections to the nose, throat and lungs grow higher, and you are also more likely to experience some type of heart failure (as the walls of the heart weaken and it can't pump enough blood to the body). 

Diagnosis

Since the disease is so rare, it is commonly misdiagnosed as cancer, aggressive juvenile fibromatosis, and progressive osseous heteroplasia. It is misdiagnosed about 80% of the time! This usually leads to doctors performing biopsies which actually worsens the disease. However, there are two signs doctors look for : the inward-pointing toes and the tumor-like lumps on the shoulders, back and neck. 

                                                                        Treatment

Unfortunately,