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About Duchenne

Duchenne Muscular Dystrophy

Muscular Dystrophy (MD) is a broad term used to label more than 20 specific gene-related disorders that affect the muscles throughout the body. Each type of muscular dystrophy differs with respect to which muscles are affected. The overall result is however, the same in that the affected muscles lose their strength over time, but at different rates of progression. Sometimes MD is confused with MS (Multiple Sclerosis) but they are very different.  MD is caused by a genetic disorder that affects muscles in the body, whereas MS is an auto-immune disease that affects the nerves in the brain, spinal cord and other part of the central nervous system.

Duchenne Muscular Dystrophy (DMD) is the most prevalent of all the Muscular Dystrophies. DMD is also the most common lethal genetic disorder diagnosed during childhood today. Diagnosed in early childhood DMD causes weakening of ALL the muscles in the body. Becker Muscular Dystrophy (BMD) is a milder version of Duchenne. The course of Becker is slower and less predictable than that of DMD>

Within our gene makeup, there is an important muscle protein called “dystrophin”.  Dystrophin is made by a gene that is found ONLY on the X-Chromosome and acts as the “glue” that holds muscles together by maintaining the structure of muscle cells. Without dystrophin, muscles become “unglued”. They are not able to operate properly and eventually suffer progressive and irreversible damage.

DMD primarily affects boys because the gene responsible for causing DMD is found on the X chromosome, making it a sex-linked disorder. Approximately 20,000 children worldwide are born annually with DMD, affecting approximately one in 3,500 boys around the world. The majority of children who have DMD inherit it, while approximately 35% of DMD cases are the result of a random or spontaneous genetic mutation. The genetic mutations that cause DMD can occur during any pregnancy. DMD occurs equally in all races and cultures.

All males have one X-chromosome and one Y-chromosome, while females have two X-chromosomes. If something is missing from the X-chromosome, females have another X-chromosome on which to “fall back”. Since males have only one X-chromosome they only have one chance to produce dystrophin.  Therefore, their bodies have no other way to produce a functional version of that damaged gene. DMD can appear in females but it is very rare.

At birth, there are no symptoms of Duchenne. However during the early years parents will notice that their son is behind their peers in reaching developmental milestones such as walking, hopping and climbing stairs. Often they will also notice that their son's calves appear to be enlarged giving the false impression that they are strong. Boys between the ages of 3 and 5 may appear to be clumsy and will often lose their balance, causing them to fall down a lot. Climbing stairs, running and rising up from the floor become very difficult and tiresome. By school age, DMD causes loss of elasticity in the Achilles tendons, which forces boys with DMD to walk either on their toes or on the balls of their feet, resulting in a "walk" that looks like a "waddle". In order to keep their balance and maintain their center of gravity, boys with DMD will protrude their bellies and push their shoulders back, a condition is called Lordosis. By about 12 years old, a boy with DMD will likely need a wheelchair for at least part of the time because his weakened muscles will cause him to tire easily. In most cases it is during the teen years when the most significant loss of muscle strength occurs. It is at this point that activities involving the arms, legs, or trunk of the body will require even more assistance. Although most young men will retain the use of their fingers thus allowing them to write, use a computer, and operate a power wheelchair, it is at this stage that the muscles in the heart and lungs become vulnerable. Heart and respiratory complications become the main threat to young men with Duchenne. The muscle layer of the heart begins to deteriorate putting the young men at risk of a heart attack.

When symptoms of DMD are managed conventionally, young men with the disorder usually die from respiratory failure before they turn 25. It has been estimated that anywhere from 9-50% of those with DMD die from cardiac failure.

There is no cure at this moment in time for DMD. However, the future is very promising thanks to the scientists and researchers all over the world whose tireless efforts have advanced the understanding and treatment of Duchenne. In the meantime, Duchenne San Diego - along with the many Duchenne Orgnizations around the country and world - is committed to creating new possibilities for the meaning of life and living for those impacted by DMD today and in the future.
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