Understanding DMD

Patient Voice spoke with Dr. Craig Campbell about Duchenne muscular dystrophy (DMD), a severe genetic disorder characterized by progressive muscle degeneration. He discusses who’s primarily affected and why, along with the various approaches to treatment that are currently being investigated.

Photography by Thistle & Rose.

Dr. Campbell is the Deputy Chair of Pediatrics (Research), the Head of the Division of Pediatric Neurology, and the Medical Director of the Multidisciplinary Neuromuscular Clinic based at Thames Valley Children’s Centre and the Pediatric Neurophysiology Laboratory at the Children’s Hospital London Health Sciences Centre.

1. What is Duchenne muscular dystrophy (DMD)?

DMD is a degenerative muscle condition. It’s a heart-wrenching diagnosis for families to receive for their child. It’s relentlessly progressive and, for parents, watching your child slowly lose their motor skills is incredibly difficult.

The impacts of DMD vary depending on the stage of the disorder. Early on, the most challenging things are the behavioural and cognitive difficulties that impact many children with DMD. There are challenges associated with things like anxiety disorders, intellectual disabilities, and adjusting at school.

The second big negative milestone is the loss of ambulation. This is often the focal point for many families – trying to prevent this loss. For many families, disease progression somehow feels like a failure. People often try everything they can to continue their child’s ambulation, sometimes even to their own risk of injury or fatigue. In the teenage years, when these children are largely in wheelchairs, some of the challenges revolve around the respiratory support of care and many will require assisted ventilation, particularly at night.

2.Who does DMD primarily affect? Why?

DMD is mainly a disorder of young males because it’s caused by a problem on the X chromosome, and males only have one X chromosome. Females have two X chromosomes, so if one is affected, the other one can compensate. DMD usually starts to become evident around the ages of three to five years old. Of course, the actual muscle damage starts before birth.

We can find evidence of muscle disruption, as reflected in the muscle enzymes in the blood, right from birth. This has led to many people advocating for newborn screening because we could then diagnose DMD early on. Unfortunately, by the time we see a child beginning to struggle at four or five years old, we know that significant muscle damage has already been done.

“DMD is mainly a disorder of young males because it’s caused by a problem on the X chromosome, and males only have one X chromosome. Females have two X chromosomes, so if one is affected, the other one can compensate.”

3.How has our understanding of DMD evolved in recent years?

In recent years, while there have been many developments in the clinical trial space, there hasn’t been a lot of change in our understanding of the disease. We’ve known the genetics and understood the profile of children with DMD for some time. We’ve gotten better at supportive care and there has been lots of research, but more is needed to fully understand what the best intervention and management is.

The things that have happened in the past 10 years that have been the bigger breakthroughs have been the coordination of, and advocacy created by, the DMD community. We have international networks of clinicians, advocacy groups, and scientists that maintain strong working relationships with pharmaceutical innovators. If you don’t have an engaged community with collaboration between multiple stakeholders, it’s extremely hard to develop novel therapeutics.

It's because of this tight-knit community that DMD is one of the most active clinical trial spaces in the rare disease ecosystem. That’s very exciting. A lot of things are setting the stage for what we hope will be a series of major breakthroughs from a therapeutic perspective.

4.Why is it a promising time for patients and their families?

It’s a hopeful time for a few reasons. Although we’ve seen a number of clinical trials fail to meet their endpoints, we can’t let ourselves be discouraged. These failures have allowed us to better understand this disease and to learn valuable lessons about its mechanisms and how best to measure outcomes.

Fortunately, there are multiple approaches to treating DMD that are currently in clinical trials – and each is exciting and promising in its own way. We have muscle modifier therapies that are looking at ways to reduce fibrosis and protect muscles from damage in a more effective way. We’re also seeing advancements in genetic-based therapies, and gene therapies, that could potentially help manipulate the dystrophin gene into producing a better protein product. 

Lastly, we’re on the verge of having new treatments that will mean these boys will have a steroid alternative, therefore avoiding the associated complications. Each would be potentially life-altering for patients and caregivers.

Dr. Campbell has focused his research on pediatric neuromuscular disease.

5.What is your advice to Canada’s DMD community?

I advise families, if they can, to reach out to the wider community and leverage the resources available. There are fantastic patient organizations in Canada that serve as a support resource. There’s a well-established network of tertiary referral centres across Canada that have expert multi-disciplinary teams at the ready.

I would say that, in Canada, we’re amongst the best countries in the world in terms of our structure and level of collaboration. We’re a small country population-wise with large geographies, but Canada has turned out to be an ideal location for DMD clinical trials and other advancements, like care, coordination, education, and advocacy.

I give credit to the patient community, my colleagues, and patient organizations for their tireless efforts to make the situation better for those living with and caring for those with DMD.

Defeat Duchenne Canada is the country’s only national charity dedicated to ending Duchenne muscular dystrophy. We have provided leadership in research, advocacy, and support since 1995. Click here to learn more.

This initiative was supported by Pfizer Canada ULC. This page and the editorial themes covered were developed by Patient Voice.