Duchenne Muscular Dystrophy: Causes, Symptoms & Diagnosis

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Medically reviewed by William C Lloyd III, MD, FACS — Written by Marissa Selner — Updated on July 14, 2023

Symptoms
Causes
Inheritance
Risk Factors
Diagnosis
Treatment
Outlook
FAQs
Takeaway

Duchenne muscular dystrophy (DMD) is a severe genetic condition characterized by progressive muscle weakening. People with DMD typically only live into their 20s, but life expectancy has been increasing over time.

Muscular dystrophy is a group of genetic conditions that cause you to lose muscle mass and strength over time. There are nine types of muscular dystrophy.

Duchenne muscular dystrophy (DMD) is the most common type of muscular dystrophy. It’s also one of the most severe, worsening more rapidly than other types.

Recent research estimates that DMD affects 48 out of every 1 million people worldwide. But rates may be higher in Europe and North America, according to the Muscular Dystrophy Association.

The symptoms of DMD begin in early childhood. Those with DMD usually die in early adulthood.

What are the symptoms of Duchenne muscular dystrophy?

Symptoms of DMD generally start to appear between ages 2 and 6. Many children with DMD develop regularly during infancy and early childhood.

DMD symptoms may include:

difficulty walking
a loss of ability to walk
enlarged calves
learning disabilities, which occur in about one-third of affected people
a lack of motor skills development
fatigue
rapidly worsening weakness in the legs, pelvis, arms, and neck

What causes Duchenne muscular dystrophy?

DMD is a genetic disease. Those who inherit it have a mutation in the gene related to a muscular protein called dystrophin.

Dystrophin keeps muscle cells intact. Its absence causes rapid muscular deterioration as a child with DMD grows.

How is Duchenne muscular dystrophy inherited?

Humans typically have 46 chromosomes. We get 23 from each biological parent, including 1 sex chromosome — an X chromosome from our biological mother and either an X or Y chromosome from our biological father.

The gene for DMD is on the X chromosome.

People assigned male at birth typically have an X chromosome from their mother and a Y chromosome from their father. If they acquire an X chromosome with a mutated copy of the dystrophin gene, they do not have a second copy of that gene to help produce the protein. This causes them to inherit the disease.

People assigned female at birth typically have two X chromosomes, one from each parent. If they acquire only one X chromosome with a mutated copy of the gene, they are likely to have a second unaffected copy. This is why DMD is much rarer in people assigned female at birth.

But even if they are unaffected by the disease, they can still carry the gene and pass it on the next generation.

Who is at risk of Duchenne muscular dystrophy?

A family history of DMD is a risk factor, but the condition may pass down without a known family history. A person can be a silent carrier of the condition. This means that a family member can carry a copy of the defective gene, but it doesn’t cause DMD in that person.

Sometimes, the gene can pass down for generations before affecting a child.

People assigned male at birth are more likely to have DMD than those assigned female at birth. The National Organization for Rare Diseases estimates it affects 1 out of every 3,500 male births.

In contrast, DMD affects about 1 in 50 million female births.

How do doctors diagnose Duchenne muscular dystrophy?

Routine wellness exams may uncover signs of muscular dystrophy. You and your child’s pediatrician may notice that your child’s muscles are weakening and that your child has a lack of coordination.

Blood tests and muscle biopsies can confirm a diagnosis of DMD.

The blood test doctors use to reach this diagnosis is called a creatine phosphokinase test. When muscles deteriorate, they release a large amount of creatine phosphokinase enzyme into the blood.

If the test detects high levels of creatine phosphokinase, muscle biopsies or genetic tests will determine the type of muscular dystrophy.

What are the treatment options for Duchenne muscular dystrophy?

There’s no cure for DMD. Treatment can only make symptoms less severe and extend life expectancy.

Corticosteroids like prednisone and deflazacort can help prolong stability and independent movement. If bone health is poor, a doctor may also prescribe bisphosphonates.

Children with DMD often lose the ability to walk and require a wheelchair by about age 12. Leg bracing may extend the amount of time a child can walk independently. Regular physical therapy keeps the muscles in the best possible condition. Steroid treatments may also prolong muscle function.

Weakening muscles can cause conditions such as scoliosis, pneumonia, and abnormal heart rate. A doctor should treat and monitor conditions as they occur.

Lung function begins to deteriorate in the late stages of the disease. A ventilator may be necessary to prolong life.

What is the outlook for people with Duchenne muscular dystrophy?

DMD is a fatal condition. According to 2022 research, the median life expectancy for people with DMD is 23.7 years. However, with diligent care, some people with DMD survive into their 40s.

But advances in medical technology are improving the outlook for people with DMD. A 2021 study found that the median life expectancy has been rising steadily, from 18.3 years in people born before 1970 to 28.1 years in people born after 1990.

The condition is degenerative, which means the need for medical care increases as the condition worsens.

As symptoms begin to appear between ages 2 and 6, the child will usually need regular monitoring by a medical team.

In the later stages of the disease, most people with DMD will need full-time care to maintain quality of life.

As the final stages of the disease emerge during the teen and young adult years, the person may need to enter the hospital or receive hospice care.

Resources for support

If you have DMD or are a parent whose child has DMD, seek support from friends and family. You can also locate support groups where you can talk and listen to others going through the same experience. The following are some resources that may help:

Healthline’s Navigating Duchenne Muscular Dystrophy program
Muscular Dystrophy Association Resource Center
Parent Project Muscular Dystrophy

Frequently asked questions

Can I prevent Duchenne muscular dystrophy?

You can’t prevent DMD before conception because it passes down through your genes. Geneticists are researching technology that may be able to prevent the mutated gene from being passed on, but they haven’t discovered a successful cure.

Genetic testing before conception can determine whether a couple has an increased risk of having children with DMD.

How do I know if I’m a carrier for Duchenne muscular dystrophy?

If you have a family history of DMD, you might be interested in knowing if you are a silent carrier. Genetic testing is the best way to know for sure if you’re a silent carrier for the gene that causes DMD.

Are there any emerging treatments for Duchenne muscular dystrophy?

Researchers are looking into several new DMD treatment strategies, but progress has proven challenging. Some medications intended to manage symptoms showed promise in early clinical phase trials but weren’t as effective in later trials.

Some researchers have proposed gene therapy as a potential cure, but attempts so far have been unsuccessful because of the size of the gene. Scientists are also looking into stem cell transplants.

Takeaway

DMD is the most common and severe type of muscular dystrophy. Symptoms usually present in early childhood, with median life expectancy in the 20s.

DMD is an X-linked genetic disease, which means it affects mostly people assigned male at birth. They usually inherit it from a biological mother who is a silent carrier.

Medical advances have increased life expectancy for people with DMD over the last few decades. Scientists hope that emerging therapies may increase it further.

How we reviewed this article:

SourcesHistoryHealthline has strict sourcing guidelines and relies on peer-reviewed studies, academic research institutions, and medical journals and associations. We only use quality, credible sources to ensure content accuracy and integrity. You can learn more about how we ensure our content is accurate and current by reading our editorial policy.

Carrier testing. (n.d.). https://www.parentprojectmd.org/care/for-carriers/carrier-testing/
Duchenne muscular dystrophy. (2023). https://rarediseases.org/rare-diseases/duchenne-muscular-dystrophy/
Duchenne muscular dystrophy (DMD). (n.d.). https://www.mda.org/disease/duchenne-muscular-dystrophy
Broomfield J, et al. (2021). Life expectancy in Duchenne muscular dystrophy: Reproduced individual patient data meta-analysis. https://n.neurology.org/content/97/23/e2304
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Paramsothy P, et al. (2022). Selected clinical and demographic factors and all-cause mortality among individuals with Duchenne muscular dystrophy in the Muscular Dystrophy Surveillance, Tracking, and Research Network. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9214635/
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Medically reviewed by William C Lloyd III, MD, FACS — Written by Marissa Selner — Updated on July 14, 2023

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