Information on Duchenne Muscular Dystrophy

When you think of Muscular Dystrophy, you probably refer to Jerry’s Kids or the Jerry Lewis Telethon.  That is the only relation we had to it also until, the day that Muscular Dystrophy rocked our world.  Our son, was only 5 years old, and seemingly remarkably healthy.  The only concern that we were having was that he was a toe walker, and as he was growing he was starting to seem a little more clumbsy.  Little did we know, we were about to embark on an adventure that no parent wants to have to travel.  Our son, was diagnosed with Duchenne Muscular Dystrophy.

Duchenne Muscular Dystrophy is the most common fatal genetic disorder diagnosed in childhood, affecting approximately 1 in every 3,500 live male births (about 20,000 new cases each year). Because the Duchenne gene is found on the X-chromosome, it primarily affects boys; however, it occurs across all races and cultures.

Duchenne results in progressive loss of strength and is caused by a mutation in the gene that encodes for dystrophin. Because dystrophin is absent, the muscle cells are easily damaged. The progressive muscle weakness leads to serious medical problems, particularly issues relating to the heart and lungs. Young men with Duchenne typically live into their late twenties.

Duchenne can be passed from parent to child, but approximately 35% of cases occur because of a random spontaneous mutation. In other words, it can affect anyone. Although there are medical treatments that may help slow its progression, there is currently no cure for Duchenne.

What Causes Duchenne?

One of our largest known genes, dystrophin is an important muscle protein that acts as a kind of glue, holding muscles together by maintaining the structure of muscle cells.

Dystrophin is also believed to carry signals between the inside and outside of muscle fibers. Without dystrophin, muscles are unable to operate properly, and eventually suffer progressive damage.

The dystrophin gene is carried on the X-chromosome. Boys have only one X-chromosome, making them more susceptible to dystrophin damage, as they lack a second X-chromosome to make up for the damaged gene.

When a boy’s body is not able to produce any dystrophin at all, he is diagnosed with Duchenne. In Becker muscular dystrophy, a shortened form of dystrophin is generated.

Duchenne is usually passed from parent to child, but many cases are the result of random spontaneous genetic mutations, which can occur during any pregnancy.

In fact, about one out of every three cases occurs in families with no previous history of Duchenne.

Who Gets Duchenne?

Duchenne  is not specific to any one group, crossing all cultures and races. What sets this disorder apart from other muscular dystrophies is that it occurs almost exclusively in young men, making it a gender-linked disorder

Why Boys?

The dystrophin gene is carried on the X-chromosome. Young men have one each of the X- and Y-chromosomes, whereas girls have two X-chromosomes. Young men are therefore at greater risk of inheriting disorders caused by damaged genes on the X-chromosome, since they lack a second X-chromosome to “make up” for the damaged gene.

How Duchenne is Identified

Newborn screening is able to detect Duchenne muscular dystrophy, but there are still many issues that need to be considered by the National Institutes of

Health (NIH) before widespread newborn screening will be available.

Observation

Parents or teachers are often the first to notice the early signs of Duchenne, such as speech delay, enlarged calf muscles, and the inability to keep up with peers.

Tests/screens

There are reliable tests to help doctors diagnose a boy with Duchenne. The following tests are typically used to confirm a preliminary diagnosis of Duchenne:

• Creatine Kinase: Creatine phosphate kinase (also known as CPK or CK) is an enzyme that normally lives inside muscles. Boys with Duchenne often have CK levels 10 to 100 times the normal range. Elevated CK levels indicate muscle damage, although a high CK does not confirm a diagnosis of Duchenne.
• Genetic Testing: (using blood cells or muscle cells) is the best way to obtain exact genetic information for a conclusive Duchenne diagnosis. The field of genetic testing is rapidly evolving, and there are several types of testing that provide accurate genetic diagnosis.

Early Phase

Physical symptoms

• The boy will typically move slower or with more difficulty than other children his age.
• He may appear clumsy and fall frequently, and have difficulty climbing, jumping, or running.
• Because of his muscle weakness, he will become tired more easily, or will have low energy.
• He may ask to be carried frequently, or need the use of a stroller for longer distances.
• Some of his muscles (in particular his calves) may appear enlarged or overdeveloped. This happens because muscle cells are being replaced by scar tissue.
• This process may also result in him being less flexible and having loss of elasticity in the joints (also known as contractures).

Braedan’s Bridge will invest in research that will impact every boy touched by Duchenne, no matter his age, stage of progression, or mutation.  We will continue to raise awareness and funds until there is a cure and our boys are safe from this awful disorder.  Thank you.

Information gathered for this flyer from Parent Project Muscular Dystrophy.