Duchenne Muscular Dystrophy
What Is Duchenne Muscular Dystrophy?
Duchenne muscular dystrophy (also called Duchenne MD or DMD) is the most common form of muscular dystrophy, a genetic disorder that gradually makes the body's muscles weaker.
What Are the Signs & Symptoms of Duchenne Muscular Dystrophy?
Children with Duchenne (dew-SHEN) MD may start walking later than average, and have large calves as toddlers. Often the disease goes unnoticed until age 3‒5, when muscle weakness affects walking, climbing steps, and other activities.
At first, children with Duchenne MD may:
- run slowly
- have trouble going up steps or getting up from the floor
- fall often
- toe walk (walking on the toes or balls of the feet) or waddle
Children with Duchenne MD also may have problems with learning.
Duchenne MD is progressive, meaning problems get worse with age. As kids with DMD become teens, they often need to use a wheelchair. Muscle weakness throughout the body can lead to heart and breathing problems.
What Causes Duchenne Muscular Dystrophy?
Muscles need a protein called dystrophin (dis-TRO-fin) to work properly. In Duchenne MD, the gene that makes this protein is mutated (changed in some way). It can’t make enough dystrophin protein needed for the muscles to work properly, and they gradually get weaker.
Duchenne MD mostly affects boys. But girls and women can be carriers of the mutated gene and have mild symptoms. They also can pass the gene to their children.
How Is Duchenne Muscular Dystrophy Diagnosed?
Doctors often diagnose muscular dystrophy based on the child's family history, symptoms, and an exam. They will also order some tests:
- Creatine kinase (CK) level: This blood test checks the level of creatine kinase, a protein that normally stays inside muscle cells. When Duchenne MD damages muscle cells, they release a lot of CK into the blood.
- Electromyography (EMG): This measures how well the muscles are working.
- Genetic testing: This will show the mistake in the dystrophin gene. This helps the medical team decide how to treat the problem and know what to expect in the future.
- Muscle biopsy: Doctors take a biopsy by removing a small piece of muscle, usually from the thigh. This test can show whether the muscular dystrophy is the Duchenne type or the milder Becker type. If the genetic testing, CK level, and physical exam point to a diagnosis of DMD, a muscle biopsy may not be done.
How Is Duchenne Muscular Dystrophy Treated?
There's no cure yet for Duchenne MD. Treatment can include:
- Medicines, such as:
- steroids, which can slow the rate of muscle damage
- an “exon skipping” medicine, which works at the level of the genes to increase the amount of dystrophin protein the body makes. This is given weekly through an IV (into a vein) line.
- gene therapy, which replaces the mutated dystrophin gene with a dystrophin gene that works
- Supportive care, which can include:
- managing infections, breathing problems, scoliosis, and heart problems
- using devices such as nighttime braces to stretch the heel cords, and scooters or wheelchairs when walking becomes harder
A child with Duchenne MD usually is cared for by a team of doctors and other experts from several pediatric specialties.
Many clinical trials are underway and new medicines are being developed to treat and potentially cure Duchenne muscular dystrophy.
What Can I Expect?
Treatment advances let kids with Duchenne MD live longer, more active lives than would have been possible 10 or 20 years ago.
Typically in Duchenne MD:
- Boys will start to use a wheelchair around age 10‒12 because of increasing muscle weakness and tiredness with walking.
- Breathing problems are carefully monitored with regular pulmonary function tests (PFTs) and sleep studies. A pulmonologist (lung specialist) will prescribe medicines to treat infections and improve breathing. Kids with Duchenne MD should receive all routine vaccines, including an updated COVID-19 vaccine, annual flu shots and a vaccine to prevent pneumonia. Kids who are treated with steroids for a long time have weaker immune systems, so the doctor will recommend the vaccines that are most appropriate for them.
- Heart function is monitored and medicines are given as needed to treat heart enlargement (cardiomyopathy) and irregular heart rhythms.
- An orthopedist (bone specialist) will do regular checks for scoliosis.
What Else Should I Know?
- Female carriers of a mutated Duchenne MD gene should have regular visits with a pediatric cardiologist (a doctor who specializes in heart problems).
- Children with Duchenne MD may have a harmful response to anesthesia. If your child must have surgery, make sure the anesthesiologist knows about the DMD.
- Adults with a known mutation in the Duchenne MD gene should consider genetic counseling before they have children.
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