Understanding Duchenne Muscular Dystrophy

Duchenne muscular dystrophy (DMD) is a rare genetic condition 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 males. Because of its impact on the musculoskeletal system, DMD is a life-limiting and life-threatening disease.¹

Causes of 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 lose their strength, becoming fragile and weak, and they gradually become damaged over time.^1-3

Populations affected by DMD

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

DMD is far more common in males than females 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

Early signs and symptoms of DMD

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

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

Other symptoms of this muscular dystrophy condition include:^2-4

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

Children with DMD typically lose the ability to walk by around age 12, requiring them to use a wheelchair. As they grow older, their muscles continue to weaken, which leads to heart and lung problems. By their teens and early 20s, heart failure becomes common. This condition occurs when the heart muscle loses its ability to pump blood effectively.^1,2,4

When scoliosis worsens alongside weakened muscles, it leads to severe lung problems and difficulty breathing. Over time, this progression can cause acute respiratory failure.^1,3,4

Diagnostic procedures for Duchenne muscular dystrophy

To make a DMD diagnosis, doctors perform a series of tests, including:^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 a loss of muscle strength. 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.

Life expectancy for individuals with Duchenne muscular dystrophy

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

Treatment and management of DMD

There is currently no cure for this muscular dystrophy condition. Instead, treatment focuses on managing symptoms, slowing the progression of the disease, and improving overall quality of life. Treatment options include:^1,4,5

• Steroids – Steroid drugs, like prednisone and deflazacort, help to slow muscle degeneration and improve strength. These medications represent 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 for maintaining and building physical strength.
• Assistive devices – Leg braces, wheelchairs, and other mobility aids can help people maintain independence as the disease progresses.
• Cardiac care – Cardiomyopathy is a common complication of DMD. Treating it often involves taking drugs that reduce the risk of heart failure. Experts strongly recommend that people with DMD have their heart monitored regularly.
• Respiratory care – Because DMD weakens the muscles used for breathing, respiratory support may become necessary. This support can include noninvasive ventilation. In severe cases, a doctor may recommend a tracheostomy. This surgery creates an opening through the neck to provide a direct airway.

Emerging research and future outlook

DMD is a challenging muscular dystrophy 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. In recent years, the US Food and Drug Administration (FDA) has approved several gene therapy drugs. Additionally, researchers continue to test other gene therapies in clinical trials.³