Duchenne muscular dystrophy is a rare disease that affects the skeletal muscles — the muscles throughout your body that allow you to move. The condition is caused by a mutation (variant) in a gene that’s essential for making a protein called dystrophin. This protein helps muscles work properly. Health care providers use several tests to diagnose DMD and rule out other conditions.

What should you do if your child is showing signs of DMD? You might wonder, when is DMD diagnosed? If you notice signs of DMD, talk to your child’s pediatrician or a health care provider who specializes in muscle disorders in children. Their pediatric health care team can recommend testing for DMD.

Here are five tests health care providers use to diagnose and track the progression of DMD.

1. Physical Exam

During an initial physical exam, the pediatrician will ask you or your child about any symptoms. They may ask how long these symptoms have been present and about any past health issues.

The pediatrician may also do neurological and muscle exams. These tests check how well your child’s nerves and muscles are working. Typical signs include frequent falls, Gowers’ sign (where your child needs to use their hands and arms to stand up from a squat), large calf muscles, and a tendency to walk on their toes.

2. Creatine Kinase Test

This test can help diagnose damage to muscle tissue by measuring levels of creatine kinase, an enzyme normally found in muscle cells. Creatine kinase levels increase when muscles are harmed by injury, inflammation, or muscle diseases like DMD or rhabdomyolysis.

A creatine kinase test can’t diagnose DMD on its own, but it can show if there are problems with the muscles. It is often the first step in finding out whether your child’s muscles are affected by a health condition.

3. Genetic Tests

If muscle problems are found, your child’s doctor may recommend genetic testing. This is the best type of test to confirm whether your child has DMD.

Your doctor may recommend a few types of genetic DMD tests. These tests look for changes in the dystrophin gene, which causes DMD. If genetic testing shows that your child has a DMD gene mutation, your doctor may also recommend testing other family members to see if they also carry these variants.

One organization, Parent Project Muscular Dystrophy, offers free genetic testing and counseling for muscular dystrophy to people living in the U.S. and Canada.

4. Muscle Biopsy

A muscle biopsy may be needed if genetic testing doesn’t find a mutation that causes DMD. During this procedure, your doctor will take a small sample of muscle tissue and send it to a laboratory for further study.

Several tests may be done on the muscle sample, including immunofluorescence, immunostaining, and Western blotting . These tests show if the dystrophin protein that causes DMD is present within muscle tissue. However, since genetic testing usually identifies gene changes, muscle biopsies aren’t often needed for most people with this neuromuscular disease.

5. Electrocardiogram

Most people with DMD don’t have heart problems early on. However, as the disease progresses, cardiomyopathy (a disease of the heart muscle) often develops.

An electrocardiogram can help detect cardiomyopathy and other DMD-related heart problems. This test measures the electrical activity of the heart, showing whether it’s beating normally and if there’s any damage to your heart muscle.

Talk With Others Who Understand

On myMDteam, the site for people with muscular dystrophy and their loved ones, members come together to gain a new understanding of MD and share their stories with others who understand life with MD.

Have you or a loved one been diagnosed with DMD? What was the diagnosis and testing process like? Share your experiences in the comments below or by posting to your Activities page.