What is DMD?

This may not be a traditional education post, however, it is educational in nature, so I hope it's okay to put it in this community. In fact, I hope that this post will educate anyone who reads it on a life-limiting muscle-wasting condition called Duchenne muscular dystrophy (DMD). I'm writing about it because early last year, my son was diagnosed with it and since that time, I've discovered that, as a rare condition, a lot of people have never heard of it - even medical personnel often look at me with a blank stare when I mention it.

That scares me. So, here is what you need to know about DMD. I write the following based upon what we experienced and using some medical journals as guidance (sources listed at the end).

What Is It?

DMD is a rare muscle wasting condition that effects approximately 1 in 5000 boys. Manifesting females are even rarer as the condition is carried on an X-chromosome, meaning that if a female has it, she is more likely to be a carrier because she starts with two X-chromosomes. Female manifestations occur in something closer to 1 in 50,000 births.

As you've seen mentioned already, DMD is a muscle-wasting condition. What that means, is that the muscles of a child with DMD will not grow the same as a healthy child. Consider when you exercise. This causes little tears in the muscle fibre, which, over time, heal, filling in with more muscle fibre. Do this repeatedly, and you experience muscle growth. A child with DMD will not have those tears fill in with healthy muscle - they will remain unfilled, or fill in with fatty useless tissue.

What this means for a person who has this condition is that they find it increasingly difficult to perform actions that healthy people take for granted. The most noticeable is walking - a child with DMD will generally lose the ability to walk by the age of 10-12. A person with DMD will also have difficulty breathing and can also develop heart problems, the most common being cardiomyopathy.

Whilst research is underway, there is currently no cure for DMD with most patients succumbing to the condition between the ages of 20-40.

How IS IT Diagnosed?

Diagnosis is formalised through a genetic test, often at the age of 2 - 3 years old, however symptoms can be present from earlier in life. For example, our son was very inactive as an infant, often content to lay on his back rather than move too much, to the point that the rear of his head became quite flat. (He still has a slight flatness to the back of his head today, however, you wouldn't likely notice it unless you were looking for it, which all of you will be now!)

There are quite a few indicators that can prompt a doctor to push for a diagnosis but there are commonalities that all DMD patients exhibit. These are:

Frequent falling;
Difficulty getting off the floor;
Struggling to use stairs, and
A waddling gait.

While these are not exhaustive, they are the most common and will lead a doctor or paediatrician to suggest taking the first step to diagnosing the condition, which is testing the levels of creatine kinase (CK) in the body. This is accomplished by a simple blood test.

I'm not sure how this is accomplished in other countries, but in Australia, a GP (general practitioner) referral is required, but once that's been obtained, a pathologist can draw the sample and send it for testing. Results are usually back in a week or less. CK levels in an healthy person generally range from 0 - 190 U/L, anything higher than that can be cause for concern. I believe anything in the 1000's or higher range should be followed up immediately. A child with DMD will often be much more elevated than that, with some measurements exceeding 20,000 U/L.

The reason for testing the CK levels is because this enzyme occurs in skeletal muscle and higher levels are indicative of muscle damage that is caused by DMD.

After a CK test has returned with an unhealthy reading, a genetic test is required to confirm DMD. This is another blood test to confirm a mutation on the dystrophin gene. Dystrophin is the largest known gene in the body with 79 exons and is found primarily in the the muscles, but is also present (in a lesser extent) in the brain, eyes and other locations. Dystrophin works to strengthen muscle fibres and protect them from injury as they contract and relax.

If the genetic test is inconclusive a biopsy can be ordered, however, my understanding is that with modern medicine this is now very rare. The genetic test is well advanced, and this will generally return the result that is needed for formal diagnosis. Once the genetic test has been confirmed and a diagnosis reached, the child will come under the care (in Australia at least) of a neurologist who oversees the treatment.

Living With DMD

After diagnosis, treatment commences, and it's important to note here, that treatment is not a cure. There isn't a cure for DMD currently. Treatment is designed to prolong muscle use, and early on, one of the primary treatments centres around keeping the patient ambulant (walking) for as long as possible.

As stated in the previous section, a neurologist generally takes point as the condition is genetic in origin. They oversee all other medical treatments. There are also other, non-medical treatments what can be used to help, and together, the aim is to provide the patient with comfort and quality of life.

Treatment varies from patient to patient, but most would require very similar assistance. When our son was first diagnosed, I didn't think much part the physical movement side of things, because that's what you read about on most websites, however, there are so many, and I mean many, different considerations when it comes to this condition.

Below is a list of specialists who we've worked with in the past 20 months since our son's diagnosis. A lot of these are added gradually over time, as they become needed:

Neurologist
Cardiologist
Endocrinologist
Ophthalmologist
Pulmonologist
Paediatrician
Physiotherapist
Behaviour consultant
Educational Assistant
Dietician

It's a long list, and like I said, a lot of these might surprise you, but dystrophin is found in a lot of places. I, for example, was shocked when our neurologist booked an appointment with an ophthalmologist, however, he explained to me that there's muscles and dystrophin in the eyes, and some DMD patients will develop eye problems. Go figure!

Conclusion

It's very liekly that I have been unable to capture the true essence of Duchenne muscular dystrophy and how it impacts on the child and family, but I hope that you've got a better understanding of this condition than you may have had five minutes ago. If you do, well, mission accomplished.

Research into a cure is difficult due to the complex nature of the condition and while there are steps forward, there are also steps backwards too. While I can't contribute to a cure, I can de my very best to spread awareness of DMD and hope that one day they will find a cure.

References

Background image in header: Unsplash - National Cancer Institute
Nature Reviews Disease Primers
National Library of Medicine
Medicine Plus

If you'd like to read a more personal account of how we moved through the diagnosis process with our sone, you can read the first part of that account here: 10,372 - Part One.