Duchene muscular dystrophy (DMD) and Becker muscular dystrophy (BMD) are two types of muscular dystrophy. They have a lot in common, but there are important differences. If you or your child has been diagnosed with DMD or BMD, it’s important to know how they are different and what to expect.

Both Are Caused by Mutations in the Same Gene

DMD and BMD are related genetic disorders. People with Duchenne muscular dystrophy or Becker muscular dystrophy have a mutation (abnormal change) in a gene called the Duchenne gene, dystrophin gene, or DMD gene. This mutation affects a protein called dystrophin, which helps muscles work properly and protects them from damage.

The muscles most affected by this gene mutation in people with DMD or BMD are the skeletal muscles (which control movement) and the heart muscle (cardiac muscle). Both disorders cause muscle weakness and are linked to a heart condition known as cardiomyopathy. This condition damages the heart muscle and makes it harder for the heart to pump blood.

According to Parent Project Muscular Dystrophy, DMD and BMD mostly affect males because the Duchenne gene is on the X chromosome. Females are usually carriers of the gene and can pass the mutation to their children. Both conditions get worse over time.

While most people with DMD and BMD have inherited the genetic mutation, in approximately 30 percent of DMD cases, the genetic mutation occurs randomly. In these cases, the genetic mutation is not passed down by a parent. BMD may also occur due to a random gene mutation.

Mutations Affect the Same Gene Differently

Even though the same gene is affected in DMD and BMD, the mutations work differently. In DMD, the mutation stops the body from making dystrophin protein. This means the protein is either completely missing from the muscles or found at very low levels.

In people with BMD, the body makes some dystrophin but not enough for proper muscle function.

Becker Muscular Dystrophy Is Less Severe

A key difference between DMD and BMD is how serious the symptoms are. The conditions can cause similar symptoms, but DMD is the most severe form of muscular dystrophy. BMD is usually milder, but in some cases, BMD can become almost as severe as DMD.

For some people with Becker MD, symptoms can be as mild as muscle cramps. More often, muscle weakness affects the shoulders, thighs, hips, and pelvis. Symptoms get worse slowly over time. By adulthood, some people with BMD may need a wheelchair, but many can walk with the help of a cane.

In Duchenne MD, symptoms develop in childhood and become severe within a few years. Most people with DMD need a wheelchair by age 12. As the condition progresses, they may also need a respirator to help with breathing. Other serious symptoms can develop, such as scoliosis (curvature of the spine) and cardiomyopathy.

Duchenne MD symptoms develop earlier and are more severe than those of Becker MD.

Approximately 33 percent of people with DMD experience cognitive problems (trouble with thinking and memory). People with DMD also have higher rates of attention-deficit/hyperactivity disorder (ADHD), anxiety, and autism.

Cardiomyopathy can develop into dilated cardiomyopathy, in which the heart muscle weakens and stretches. This condition can be life-threatening for people with both DMD and BMD.

DMD and BMD Develop at Different Ages

DMD symptoms usually start in early childhood. By age 6 or sooner, disability becomes noticeable. In some cases, symptoms can appear as early as infancy. Early symptoms usually affect the pelvis and legs, causing frequent falls and trouble walking, running, standing up, or climbing stairs.

BMD symptoms often start between ages 5 and 15, but they can begin even later.

DMD develops in early childhood, while BMD develops between the ages of 5 and 15 — sometimes later.

Duchenne Muscular Dystrophy Is More Common

Both Duchenne MD and Becker MD are rare diseases. However, DMD is about three times more common than BMD.

A large systematic review and meta-analysis of medical articles in the Journal of Orthopaedic Surgery and Research determined that there are approximately 4.8 cases of DMD per 100,000 people. BMD occurs in just 1.6 cases per 100,000 people.

Diagnostic Tests Can Differ for Children With Duchenne MD

Some tests used to diagnose Duchenne MD or Becker MD are the same, but others are only used only if there’s evidence of DMD.

Doctors often test for muscular dystrophy in young boys who show signs of muscle weakness that gets worse, especially if there’s a family history of MD. Tests may include:

• Blood tests — Checks for an enzyme called creatine kinase, which leaks from damaged muscles
• Genetic tests — Looks for mutations in the Duchenne gene
• Muscle biopsy — Examines a sample of muscle tissue to look for dead or enlarged muscle cells and muscle fibers
• Electromyography — Measures electrical activity in the muscles

If there is evidence of Duchenne muscular dystrophy, two additional tests are usually done by age 6 to check for heart damage:

• Electrocardiography — Measures the heart’s electrical activity to check heartbeat and heart rate
• Echocardiography — Uses ultrasound to see how well the heart muscle is working

If there’s early evidence of DMD, doctors may conduct other tests before age 6 to see if there’s damage to the heart.

Treatment Recommendations Are Similar for Duchenne and Becker MD

There’s no cure for Duchenne muscular dystrophy or Becker muscular dystrophy, but both conditions can be managed. People with BMD often live into adulthood, with an average life expectancy of about 47 years of age. If heart problems are well managed, some people with BMD can live a normal lifespan.

For people with DMD, life expectancy has improved significantly in recent years, thanks to better heart and respiratory care. In the past, many people with DMD didn’t live past their teens. Now many people with DMD live into adulthood and reach their early 30s.

Similar Treatment Options

Some treatments for DMD and BMD are similar, depending on a person’s needs. Common treatments include:

• Mobility aids, including standing frames, braces, and wheelchairs, to help with movement
• Physical therapy and exercise to treat contractures (scarred and stiff joints and muscles) and help preserve range of motion
• Gentle exercise, such as aquatic (water) therapy, to strengthen muscles without causing damage
• Cognitive support, including testing and support for cognitive impairment, such as memory problems
• Diet changes to manage weight, constipation, trouble swallowing, or low calcium or vitamin D levels
• Breathing support, including pressurized air machines or full-time ventilation devices, especially for people with DMD

Medications and Other Treatment Options

If abnormalities in the heart are found in imaging tests, doctors may prescribe heart medications like angiotensin-receptor blockers, ACE inhibitors, and beta-blockers. These drugs may help slow heart damage.

In some cases, a heart transplant may be recommended for people with BMD if their skeletal muscles are strong enough.

For people with DMD, corticosteroids like prednisone and deflazacort (Emflaza) have been shown to improve muscle strength and function, increase pulmonary (lung) function, decrease the risk of scoliosis (curved spine), and delay the loss of mobility.

Corticosteroids may also be used for severe cases of BMD, but more research is needed to know how well they work for BMD.

Newer Treatments for DMD

New genetic drugs are showing promise in slowing disability for people with DMD. Two types of drugs have been developed recently, including exon-skipping drugs that help the body make functional dystrophin, which improves muscle function. These drugs are appropriate for approximately 30 percent of people with DMD who have a specific gene mutation. Exon skipping drugs include:

• Casimersen (Amondys 45)
• Eteplirsen (Exondys 51)
• Golodirsen (Vyondys 53)
• Viltolarsen (Viltepso)

Delandistrogene moxeparvovec-rokl (Elevidys) is another type of gene therapy drug that has been approved to increase the production of functional dystrophin in people ages 4 and older with specific variants of DMD.

If you have questions about treating DMD or BMD, talk to your doctor. Your healthcare provider can give you more information about newer treatments that might work for you or your child. Your doctor can also tell you about clinical trials for new medications that you or your child might be able to join.

Connect With Others Who Understand

On myMDteam — the social network for people living with muscular dystrophy and their loved ones — members share their experiences, ask questions, and find support from others who understand the challenges of living with MD.

Have you or a loved one been diagnosed with Duchenne muscular dystrophy or Becker muscular dystrophy? Share your experiences in the comments below, or start a conversation by posting on your Activities page.