Understanding Duchenne Muscular Dystrophy

Duchenne muscular dystrophy (DMD) is a rare genetic disorder that causes muscle weakness and degeneration that gets worse over time. It is the most common and, unfortunately, one of the most severe forms of muscular dystrophy.¹

DMD usually begins in early childhood. It mostly affects men. Because of its impact on the musculoskeletal system, DMD is a life-limiting and life-threatening disease.¹

What causes Duchenne muscular dystrophy?

A change (mutation) in the DMD gene causes DMD. This gene is responsible for producing a protein called dystrophin. Dystrophin keeps muscle cells intact and functioning. Without enough dystrophin, muscle cells are fragile and weak, and they become damaged over time.^1-3

Who does it affect?

DMD almost exclusively affects people assigned male at birth. Experts estimate that about 1 in 3,600 male infants have DMD. DMD can occur at random or be inherited. It can affect all races and ethnicities.^1,2,4

DMD is far more common in men than women because of the way it is inherited. But in rare cases, it can affect people assigned female at birth. They can be carriers of the disease and pass it on to their children.^1-3

What are the symptoms of Duchenne muscular dystrophy?

The signs of DMD usually appear in early childhood, between the ages of 2 and 5. Parents may notice that their child has trouble:^2-4

• Walking and running
• Climbing stairs
• Raising their arms
• Getting up from the floor

Other Duchenne muscular dystrophy symptoms include:^2-4

• Frequent falls
• Waddling gait
• Curving of the spine (scoliosis)
• Extreme tiredness (fatigue)
• Learning difficulties

By around age 12, children with DMD lose the ability to walk and must use a wheelchair. As they grow older and muscles continue to weaken, heart and lung problems occur. By their teens and early 20s, heart failure is common. This term refers to when the heart muscle loses its ability to pump blood effectively.^1,2,4

Worsening scoliosis, together with weakened muscles, leads to lung problems and difficulty breathing. This can eventually cause acute respiratory failure.^1,3,4

How is Duchenne muscular dystrophy diagnosed?

To make a DMD diagnosis, doctors perform a series of tests that include:^1,2,4

• Physical exam – Doctors check for muscle weakness, especially in the legs and pelvis.
• Blood tests – Higher levels of creatine kinase in the blood can suggest muscle decline. Creatine kinase is an enzyme that leaks out of damaged muscle cells.
• Genetic testing – This test can identify mutations in the DMD gene. This is the most definitive test for DMD.
• Muscle biopsy – In some cases, doctors take a small sample of muscle tissue to check for dystrophin.

What is the life expectancy of someone with Duchenne muscle dystrophy?

The life expectancy of people with DMD has greatly improved over the years. In the past, most people with DMD would live only to their teens. Now, thanks to advancements in medical care and supportive treatments, people with DMD can live into their 30s.^1,3

How is Duchenne muscular dystrophy treated?

There is currently no cure for DMD. Treatment focuses on managing symptoms, slowing the progression of the disease, and improving quality of life. Treatment options include:^1,4,5

• Steroids – Steroid drugs, like prednisone and deflazacort, help to slow muscle degeneration and improve strength. Steroids are the most common treatment for DMD.
• Physical therapy – Physical therapy can help maintain muscle strength and flexibility. Stretching exercises and low-impact activities like swimming and cycling can be helpful to maintain and gain strength.
• Assistive devices – Leg braces, wheelchairs, and other mobility aids can help people maintain independence as the disease progresses.
• Cardiac care – Treating cardiomyopathy, a common complication of DMD, can involve taking drugs that reduce the chance of heart failure. Experts recommend that people with DMD have their heart monitored regularly.
• Respiratory care – As DMD affects the muscles used for breathing, respiratory support may be necessary. This can include noninvasive ventilation. In severe cases, a tracheostomy may be needed. This is a surgery that creates an opening through the neck to provide an airway.

Emerging research

DMD is a challenging condition. But advancements in medical care and research offer hope.^1,3

Nonsteroidal drugs show promise and may have fewer side effects than steroids. Gene therapy has made excellent progress as well. Several gene therapy drugs have been approved by the US Food and Drug Administration (FDA) in recent years. And other gene therapies continue to be tested in clinical trials.³