What is Duchenne muscular dystrophy?
Duchenne muscular dystrophy (DMD) is an inherited condition and the most common type of muscular dystrophy. It causes weakness in the muscles involved with movement, breathing, and heart function. The disease mainly affects people who are assigned male at birth, with symptoms beginning during the first few years of life and getting worse over time. Although people assigned female at birth aren’t usually affected, they may have mild symptoms or heart issues related to DMD.
Penn Medicine’s specialists use advanced therapies to slow the progression of the disease. With one of the oldest neuromuscular programs in the nation, we draw on a long history of providing exceptional nerve and muscle disease care. We also specialize in cardiovascular care at our Duchenne and Becker Carrier Clinic, which is part of the Center for Inherited Cardiovascular Disease. With our expertise and access to the latest treatments, we provide the highest quality care for people with DMD.
How DMD affects your body
Muscle weakness from Duchenne muscular dystrophy usually begins between ages two and four. It can also occur in infants, but parents may not notice weakness until their child is a toddler. Muscles in the hips, thighs, shoulders, and upper arms are affected early in the disease, with many needing a wheelchair by age 12. Over time, DMD also affects the heart and breathing muscles.
DMD symptoms include:
- Developmental delays, including sitting up, standing, walking, and speaking later than usual
- Waddling when walking, and trouble running and jumping
- Enlarged calves and toe walking
- Scoliosis
- Fatigue
- Learning disabilities
- Breathing problems
- Heart conditions, including cardiomyopathy and arrhythmia
The link between DMD and your genes
Duchenne muscular dystrophy is caused by a gene change (mutation) that occurs on the dystrophin gene, which makes a protein that protects your muscles from damage. When your body can’t make dystrophin, it quickly leads to muscle degeneration and weakness. Researchers have found thousands of gene mutations that can cause DMD. A similar disease called Becker muscular dystrophy (BMD) is also caused by a mutation of the dystrophin gene, but BMD is milder than DMD.
The dystrophin gene is on the X chromosome. People assigned male at birth are more likely to have DMD because they have only one X chromosome passed down from their mother. Because people assigned female at birth have two X chromosomes, they’re less likely to have symptoms because they typically have a second dystrophin gene that works properly. Genetic counseling can help adults with a DMD gene mutation understand the risk of passing the gene to their children.
Diagnosing Duchenne muscular dystrophy
Talk to a pediatrician if you’re concerned about your child’s development. The doctor will ask about your child’s symptoms and medical history and can conduct physical and neurological exams. People with DMD can have high creatine kinase levels in their blood, which can be checked with laboratory tests. Genetic testing can help identify the specific DMD gene mutation to help guide treatment. Other tests, like taking a small sample of muscle for examination and checking heart and respiratory function, may also be recommended.
Therapies and treatments that slow DMD progression
Treatments can’t cure Duchenne muscular dystrophy, but they can slow down muscle degeneration. Corticosteroids can help maintain muscle strength and function, and other drugs can reduce inflammation or inhibit an enzyme to protect muscles from damage. There are also therapies that address the genetic cause of DMD. Exon skipping therapy helps the body create a shorter form of the dystrophin gene to make the disease’s symptoms milder. Gene therapy can deliver a modified dystrophin gene to people with certain gene mutations.
Other therapies can help your child manage DMD symptoms. Physical and occupational therapy can help improve strength, range of motion, and functioning. It’s also important to see heart and respiratory specialists for any heart or breathing problems that may develop.
Duchenne muscular dystrophy and life expectancy
People with Duchenne muscular dystrophy have a shorter lifespan, although treatment can help prolong life. People with DMD may live into their twenties, thirties, or forties.
Coordinated care for muscular dystrophy
Penn Medicine offers precise diagnostic testing and access to the latest treatments for Duchenne muscular dystrophy, helping your child receive therapies that can help them live longer and with less disability. Because we also actively research neuromuscular disorders like DMD, your child may have the opportunity to participate in a clinical trial at Penn Medicine.
A key benefit of our DMD care is the collaborative approach we take to your treatment. Our neuromuscular specialists work with cardiologists, pulmonologists, physical and occupational therapists, and other experts to give your child well-rounded care to manage all DMD symptoms. Experts in genetic testing and services can also provide information about specific gene mutations that cause the disease. And through the Duchenne and Becker Carrier Clinic, we’re one of the first centers with specialists who can identify and treat heart conditions in people who carry the gene that causes DMD. We’re here to help guide and support you and your family manage this complex disease.