The videos show children and adults, some seemingly frozen in position, standing straight or with twisted arms and legs. All have fibrodysplasia ossificans progressiva (FOP), a disorder in which normal muscle tissue is gradually turned into bone. The Skeleton Key, an excellent program produced by BBC Horizon (U.K.) and also shown on the Discovery Health Channel (U.S.), gave many viewers their first glimpse of this devastating disorder.
A unique condition
There is no other known disorder where one type of body tissue is transformed into another. Only about 1 person in 2,000,000 people worldwide is affected by FOP. In the disorder, white blood cells which normally attack invading diseases destroy healthy muscle tissue instead. A malfunctioning bone-building protein (called BMP) produces bone to take the place of the muscle. Gradually, pieces of bone form throughout the person's body.
Restricted movement causes problems
Some of these abnormal bone pieces connect to each other, and to normal bones, limiting movement, even freezing joints in place. If the excess bone is in the rib cage or neck, breathing can be restricted, to the point of suffocation. If in the jaw, eating and talking are affected. Viewers of the TV program saw both children and adults unable to walk, turn their heads, or lift their arms up. FOP makes it difficult for people to take care of themselves and do many things that others take for granted, like getting out of bed or using a fork.
Research moving towards causes . . .
Scientists involved in research on FOP believe that the gene which causes bones to develop in a baby prior to birth stays "turned on" and continues to instruct the body to make bones. This idea was borne out by the discovery of a malfunctioning bone-producing protein called BMP. One of the genes controlling BMP must be the one involved in FOP. Researchers have yet to locate the exact gene, but they are looking among the thousands of possibilities in hopes of finding it.
. . . and treatments
If scientists couldn't find the malfunctioning gene to "turn it off," then perhaps they could find a way to counteract the BMP and stop the production of new bone. They realized that bone cells need blood to form, and tiny new blood vessels form around a place where bone is growing. If the new blood vessels could be prevented from forming, the new bone couldn't develop.
Several medications are being tested for their ability to slow or stop blood vessel formation during bone growth in FOP, including thalidomide, squalamine, and Cox-2 inhibitors.
In addition, a protein called noggin has been found to interfere with bone growth caused by BMP. Researchers are working on using gene therapy to increase noggin production in people with FOP.
The International Fibrodysplasia Ossificans Progressiva Association has information on all of the research and clinical trials in progress.
Information for this article was taken from:
- BBC Horizon. Skeleton Key: The race to find a cure for FOP.
- International Fibrodysplasia Ossificans Progressiva Association
