What is Duchenne muscular dystrophy?

Learn about dystrophin, symptoms, and care to help you better understand and navigate the Duchenne journey.

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What Is Duchenne Muscular Dystrophy?

Duchenne muscular dystrophy (also called Duchenne or DMD) is a genetic condition where muscles progressively get damaged and weaker over time.

Duchenne is caused by a genetic mutation to the dystrophin (DMD) gene. A DMD gene mutation causes people living with Duchenne to have little to no dystrophin—a vital protein which helps to strengthen and protect muscles.

300,000 Globally

There are around 15,000 people living with Duchenne in the United States and more than 300,000 globally.

Challenges

People with Duchenne face significant challenges, including movement limitations, learning and developmental delays, and heart and breathing problems. 

Understanding Duchenne

Diagram of an exon within the dystrophin gene Diagram of an exon within the dystrophin gene

It's all about dystrophin

In order to function properly, our muscles need dystrophin. Dystrophin is a key part of a group of proteins that all work together to strengthen and protect muscles as they contract and relax.

Duchenne is caused by a mutation in the dystrophin gene

Due to a genetic mutation, people with Duchenne make little or no usable dystrophin. A genetic mutation can mean a couple of things. Some mutations cause deletions, which means a person is missing one or more exons from their dystrophin gene. Some cause other changes to the gene that stop it from working properly.

Without usable dystrophin, people with Duchenne gradually lose healthy muscle tissue. This leads to common DMD symptoms, including muscle weakness, balance issues, and serious health complications over time.

Signs and Symptoms of Duchenne

Some symptoms of Duchenne can be seen as early as 4 months of age. If you suspect your loved one may have Duchenne, be sure to discuss the symptoms with your doctor. There are treatment options available that can help promote dystrophin production and manage the symptoms of Duchenne.

Stages of Duchenne symptoms

While Duchenne is unique to each individual, there is a timeline that symptoms tend to follow as the condition progresses.

Early symptoms (0-5 years)

  • Delayed milestones like sitting, crawling, walking, or talking
  • Calves that look bigger than normal
  • Walking on toes and/or a waddling gait
  • Difficulty running, jumping, or climbing stairs
  • Frequent falling/what appears to be clumsiness
  • Needing to “walk” hands up the legs to get to a standing position (called the Gower’s Maneuver)

School age (5–10 years)

  • Weak muscles in the legs and arms
  • Increased difficulty climbing stairs, getting up from the floor, or keeping up with peers
  • Tiring easily, especially when walking or playing
  • Loss of balance
  • Cognitive challenges (learning differences, attention deficits, autism spectrum disorder)
  • Behavioral issues (hyperactivity, anxiety, mood disorders)

Late childhood/teenager (10–15+ years)

  • Loss of ambulation (ability to walk)
    • Some use of wheelchair or other assistive device, with eventual need for full-time use
  • Muscle/joint pain
  • Slower growth (shorter/smaller than peers)
  • Increased weakness in the arms, neck, and trunk
  • Curving of the spine (scoliosis)
  • Weakening of heart muscle (cardiomyopathy)
  • Effects on respiratory (breathing) muscles, including weakened cough and infections

Adult (18+ years)

  • Increased difficulty with arm and hand function
  • Advanced weakness in heart muscle
    • Increased monitoring and treatment of cardiomyopathy
  • Increasing need for help with daily tasks (eating, personal care) and hobbies
  • Greater need for breathing assistance

What Is Cardiomyopathy?

Cardiomyopathy is a general term for any disease of the heart muscle.

In Duchenne, the lack of dystrophin can damage the heart muscle. This can cause the heart to weaken over time, making it harder for it to pump blood throughout the body.

Over time, most children and young adults will develop cardiomyopathy. In fact, 60% of boys with DMD show signs of cardiomyopathy by age 10, and that number increases to 90% by age 18.

Symptoms of cardiomyopathy

Excessive fatigue

(being more tired than usual)

Respiratory changes like shortness of breath

At first this can come with activity or exercise, but as cardiomyopathy advances, it may happen while sitting or lying down

Fluttering, rapid, or irregular heartbeats

(also called heart palpitations or arrhythmias)

Vomiting or stomach pain

Weight loss

These symptoms may be hard to detect in people living with DMD.

Doctor making a heart symbol with hands in front of chest Doctor making a heart symbol with hands in front of chest

Monitoring cardiomyopathy

Unlike the decline of other muscles that are more visible, cardiomyopathy can begin before symptoms are noticeable. It’s also easy to assume that some of these symptoms are being caused by other Duchenne complications, so it’s very important to be proactive about heart health. This means scheduling regular checkups with a cardiologist as part of your Duchenne care plan, starting at a young age.

During these checkups, a cardiologist can monitor heart health to detect any potential problems and determine the best time to start heart treatments.

A cardiologist may use one of these special tests to check the heart:

  • Electrocardiogram (EKG/ECG): A simple and quick test that records the electrical signals that make your heart beat to check for any signs of damage
  • Cardiac magnetic resonance imaging (MRI): A special type
    of test that gives doctors a very detailed picture of the heart. It can take 30-90 minutes and requires remaining still during the scan
  • Echocardiogram (echo): A simple test that uses sound waves to create moving pictures of the heart
Hands stacking building blocks with medical icons Hands stacking building blocks with medical icons

Treatments

Certain medications used for other heart conditions have been found to help prolong heart strength in people with Duchenne.

Your doctor can help determine the best treatment options and timing.

Learn more about cell therapy and other treatment options for Duchenne.

Get treatment info

Duchenne Care Team

For people with Duchenne, a multidisciplinary care team can provide a more comprehensive and specialized care experience. The team may include specialists such as:

Neuromuscular specialists typically coordinate care across a team of specialists and evaluate treatment options.

Neuromuscular specialists typically coordinate care across a team of specialists and evaluate treatment options.

Emmet sitting on the floor playing with blocks Emmet sitting on the floor playing with blocks

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Triston and Nicholas, both living with Duchenne, smiling together Triston and Nicholas, both living with Duchenne, smiling together

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