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What Will the Doctor Do to Diagnose DMD?


How DMD is diagnosed

Confirming signs and symptoms

If Duchenne muscular dystrophy (DMD) is suspected, the first thing your family doctor will do is perform a physical exam to check for muscle weakness. They will also ask about delays in early developmental milestones, such as sitting, walking, and standing up from the floor.

Performing a blood test

Your doctor will usually recommend a special blood test called a creatine kinase (CK) test. This involves taking a small sample of blood, which will be sent to a lab for analysis. If your child or young person has high CK levels, another sample of blood may be taken to test for changes in genes (called mutations) that cause DMD.

Referring a specialist

If your doctor becomes concerned that your child or young person needs further testing, they will usually refer them to a neuromuscular specialist. The specialist will then work to identify the cause of the symptoms and may recommend genetic testing.

Genetic testing

Genetic testing is the only way to confirm a DMD diagnosis. It can also identify the specific genetic cause of the individual’s DMD to help narrow down treatment options, qualify a patient to participate in a clinical trial and check whether an individual is a Duchenne gene carrier, so appropriate steps can be taken.

What is a CK test?

A CK test checks for an enzyme called creatine kinase, or CK. When muscle fibers are damaged, CK leaks out into the bloodstream. The muscle damage caused by DMD means that the level of CK in the blood will often be higher than normal. 

High CK levels in the blood do not automatically mean that your child or young person has DMD. Genetic testing is the only way to confirm a DMD diagnosis.

The following no-cost testing programs are available:

Decode Duchenne provides no-cost genetic testing, interpretation, and counseling through PPMD and PerkinElmer.

Detect MD provides no-cost genetic testing, interpretation, and counseling through Invitae.


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Date of preparation: September 2022

Important Terms and Concepts

Basic terms and key definitions

Neuromuscular disorders

Neuromuscular disorders affect the muscles and nerves, and most of the causes are genetic. This means they are either passed down through the family or caused by changes in an individual person’s genes.

Most neuromuscular disorders cause muscle weakness that worsens over time. Signs and symptoms of neuromuscular diseases can vary and may be mild, moderate, or severe.

Most often, when a child has a neuromuscular disease, they don’t grow and develop as fast as other children their age. They are often slow to start lifting their head, sitting, walking, and talking.

Treatment and supportive care may improve the symptoms of a neuromuscular disorder, increasing mobility and even life expectancy.

Muscular dystrophy

Muscular dystrophy is the term for a group of neuromuscular disorders that cause muscle weakness and muscle loss.

Duchenne muscular dystrophy (DMD) is a type of muscular dystrophy that causes muscle weakness that worsens over time. The progression and symptoms can vary from person to person.