Unless there is a family history of the disorder, the journey towards a Duchenne diagnosis is not always straightforward.
In fact, many families may seek answers from multiple sources regarding their child’s developmental delays before they are referred for diagnostic testing. The reason for this is that every child develops at a different rate, so care providers often resist hasty diagnoses and wait to see if the child will “catch up” to their peers.
Additionally, the signs of Duchenne can be subtle and broad, and the rarity of the disorder means that it is not frequently top-of-mind for pediatricians or family practitioners. However, receiving a timely and accurate diagnosis is a crucial aspect of care. Do not be afraid to ask questions and insist on additional testing or seek a second opinion.
If you are curious about how some of our Defeat Duchenne Canada families received diagnoses, listen to and read their stories here.
Duchenne muscular dystrophy diagnosis.
When a parent has concerns and recognizes their child is experiencing signs and symptoms associated with Duchenne, their first stop should be to their pediatrician or general practitioner.
During this visit, it is unlikely you will receive a diagnosis, but your primary care provider will be able to refer you to the right specialist for appropriate testing. They will likely perform a physical exam and send your child for a blood test for creatine kinase (CK).
Creatine kinase (CK) is an enzyme found in the heart, brain and skeletal muscles. Very high amounts of CK are released into the blood when there is muscle damage, and in Duchenne, this can be 10 to 100 times above normal. If your child’s CK levels come back higher than normal, your primary care provider should refer you to a neuromuscular specialist or neurologist for further testing.
Confirming your child’s Duchenne diagnosis.
A confirmation of Duchenne is achieved through a genetic test. This is a simple blood test where they look at your child’s DNA to find a mutation or changes to the DMD gene. In some cases, these mutations can be large deletions or duplications to part of the DMD gene. In other cases, the mutation may just be a small change referred to as point mutations or nonsense mutations. All these mutations result in the DMD gene not able to make a functional dystrophin protein which is essential for muscle structure and function.
Click here to learn more about the genetics of Duchenne and Becker muscular dystrophy.
Click here to learn more about the role of dystrophin.
Sometimes it may take two genetic tests to confirm a diagnosis, and, in rare instances, a muscle biopsy may be necessary. In this case, a small sample of muscle is surgically removed and tested for dystrophin. The muscle tissue is stained with a special dye that allows you to see the dystrophin protein. In the case of Duchenne, the cells will not stain as there is a lack of dystrophin in the muscle cells. Upon recognizing this lack, the diagnosis of Duchenne can be confirmed.
Understanding your genetic test.
Below is an example of what your genetic test result might look like. You will be asked to meet with a genetic counsellor to review your results, and they will answer any questions you may have. This will be a lot to take in and you may want to meet with your genetic counselor a few times. Take your time: your care team and Defeat Duchenne Canada are here to support you when you are ready.
Click here to learn more about your Duchenne care team.
Don’t forget, we’re here for you. Contact us directly for more information.
Want to learn more about genetic and diagnostic testing?
Watch our latest webinar with Dr. Kimberly Amburgey, Genetic Counsellor in the Division of Neurology and The Hospital for Sick Children (SickKids) in Toronto, ON.