Duchenne muscular dystrophy (DMD) is a progressive muscle disease that usually appears in early childhood. As the most common inherited muscle disorder in children, DMD causes muscle weakness over time, making movement less stable. If you’re a new or expecting parent, you might wonder if there’s a way to prevent DMD or slow it down.

Duchenne muscular dystrophy is a genetic condition (passed down through family DNA), so it can’t be prevented. However, early diagnosis can help guide treatment, give you access to support groups, and connect you with ongoing clinical trials for new therapies. Although there’s no cure, early intervention may help slow DMD progression so your child can maintain their muscle strength longer.

Although you can’t prevent DMD, understanding how it starts and what signs to look for can help you get the support you need. Here are six key facts about Duchenne muscular dystrophy.

1. DMD Stems From Mutations of the Dystrophin Gene

DMD is caused by a mutation in the dystrophin gene, which is located on the X chromosome. Sometimes called the DMD gene, this gene provides instructions for making dystrophin, a protein that helps muscles stay strong and stable. When the gene is mutated (changed in a way that prevents it from working properly), the body can’t produce enough dystrophin. Without this protein, muscle cells become weak, fragile, and prone to damage.

Although you might notice some symptoms as early as 4 months, the most common age range for DMD diagnosis is between 2 and 5 years.

Because the dystrophin gene is on the X chromosome, DMD mostly affects boys, according to the Muscular Dystrophy Association. Typically, females have two X chromosomes (XX), while males have one X and one Y chromosome (XY). If a female inherits a mutated dystrophin gene, the second X chromosome can often compensate by providing a working copy. Males typically have only one X chromosome, and without a backup, a person is much more likely to develop DMD.

2. Early Symptoms May Point to a Need for Testing

Muscle degeneration from DMD can begin at birth, but symptoms usually aren’t noticeable until a child starts growing. Some symptoms may appear in babies as young as 4 months, but a DMD diagnosis is usually made between ages 2 and 5 years. Symptoms of DMD become more apparent as a child reaches key developmental milestones, such as crawling, walking, and talking.

The main symptom, muscle weakness, typically starts in a child’s core muscles before affecting the limbs, beginning with the legs. Recognizing these early signs can help you decide when to seek diagnostic testing.

Early signs and symptoms of Duchenne muscular dystrophy include:

• Slow or difficult movement
• Clumsiness and frequent falling
• Difficulty walking, running, jumping, or climbing
• Tendency to become tired or lack energy
• Large-looking or overdeveloped leg muscles (caused by scar tissue buildup)
• An inward curvature of the spine
• Waddling gait (a swaying, side-to-side walk) or walking on tiptoes
• Delayed speech and language development
• Gower’s sign (using hands to “walk up” the legs when standing up)

Over time, DMD can weaken the heart muscle or lead to respiratory failure. In addition to the physical symptoms, children with DMD often have neurodevelopmental conditions (those that affect the development of the brain and nervous system). These include autism spectrum disorder and attention-deficit/hyperactivity disorder (ADHD), which can contribute to learning, social, and behavioral challenges.

If you notice these early symptoms in your child, don’t wait to talk to their pediatrician. Research shows that caregivers who suspect developmental delays are correct at least 80 percent of the time. Plus, since it can take up to two years from the first symptoms to get a DMD diagnosis, bringing up concerns early can help your child get the care and support they need sooner.

3. Diagnostic Tools Guide DMD Treatment

Several diagnostic tests can suggest DMD in a child with symptoms, but a confirmed diagnosis requires genetic testing. After a physical exam and a review of your family history, your child’s healthcare provider might recommend one or more tests.

Creatine Kinase Testing

People with DMD typically have high levels of an enzyme called creatine kinase (CK), which leaks out of damaged muscles. A CK test is a simple blood test that helps doctors determine if muscle weakness or developmental delays are linked to a neuromuscular condition like DMD.

A creatine kinase test can help confirm whether muscle weakness or developmental delays are linked to a neuromuscular condition like DMD.

In many cases, infants and young children with DMD have high levels of creatine kinase even before symptoms appear. CK levels in children with DMD peak by age 2, then gradually fall as fat and scar tissue replace damaged muscle.

Muscle Biopsy

Thanks to advances in genetic testing, muscle biopsies aren’t commonly used to diagnose DMD. However, a muscle biopsy can provide more information, especially if genetic test results are inconclusive.

During a muscle biopsy, a doctor surgically removes a small sample of muscle tissue, usually from the thigh or calf muscle, to be examined in a laboratory. This test can help confirm DMD and distinguish it from other types of muscular dystrophy, such as Becker muscular dystrophy.

4. Advances in Genetic Testing Support Earlier Diagnosis

Genetic testing for DMD examines DNA in your child’s cells to look for dystrophin gene mutations that point to DMD. This usually involves a blood test. If the mutation is found, it can confirm a DMD diagnosis.

Your child’s pediatrician may recommend genetic testing for DMD if a CK test shows high serum CK levels. Several types of genetic tests for DMD can help identify the specific mutation, which guides treatment — different drugs target specific gene mutations.

Genetic testing for DMD examines DNA in your child’s cells to look for dystrophin gene mutations that point to DMD.

According to the Muscular Dystrophy Association, females who have a relative with DMD can undergo genetic testing to find out if they’re carriers, meaning one of their two X chromosomes has the dystrophin mutation. Although carriers may not have DMD themselves, they can pass the mutation to their children. In rare cases, women and girls who are carriers may develop DMD symptoms such as muscle weakness or heart problems, which might not show up until adulthood.

5. Genetic Counseling Can Help Your Family Make Decisions

Genetic counseling often goes hand in hand with genetic testing. A genetic counselor can help you decide which genetic tests to get for DMD. They can also interpret the results so your family can make informed decisions. Genetic counseling can help you:

• Learn more about DMD and how it’s inherited
• Ask questions and receive knowledgeable guidance
• Decide if carrier screening is right for you
• Explore family planning options
• Access research opportunities, such as clinical trials

6. Early Detection Leads to Better DMD Management

Duchenne muscular dystrophy can’t be prevented, but early detection can improve management and long-term outcomes. Researchers continue to study promising therapies to help repair muscle and reduce muscle damage.

Disease-modifying therapies for DMD are now available and work best when started early, before irreversible muscle damage happens. Gene therapy, for example, aims to introduce a functional version of the dystrophin gene in children with DMD to help slow muscle damage.

Talk to your doctor about testing for DMD, treatment options, and available clinical trials that may benefit your child.

Talk With Others Who Understand

On myMDteam, the social network for people with muscular dystrophy and their loved ones, members come together to ask questions, give advice, and share their stories with others who understand life with muscular dystrophy.

Do you care for someone with Duchenne muscular dystrophy? Have you taken steps to help slow the progression of DMD? Share your experience in the comments below, start a conversation by posting on your Activities page, or connect with like-minded members in Groups.