Duchenne Muscular Dystrophy: Causes, Signs & Care Canada

Duchenne muscular dystrophy is one of the most common inherited muscle diseases, affecting approximately 1 in 3,500 to 4,500 boys born in Canada. This serious genetic condition causes progressive muscle weakness that typically appears in early childhood and worsens steadily over time. While there is currently no cure, early diagnosis and proper care can make a meaningful difference in quality of life for affected children and their families.

What Causes Duchenne Muscular Dystrophy and How Does It Develop?

Understanding DMD in children is essential for Canadian parents who want to recognise the early warning signs and access the best available support. This article explains what Duchenne muscular dystrophy is, how it develops, what muscular dystrophy symptoms to watch for, and what treatment and management options are available through the Canadian healthcare system.

What Is Duchenne Muscular Dystrophy?

Stages of Duchenne Muscular Dystrophy: Characteristics and Management

Stage	Age Range	Key Characteristics	Management Approach
Early Ambulatory	2–7 years	Delayed walking, frequent falls, toe-walking, calf pseudohypertrophy, Gowers’ sign when rising from floor	Corticosteroid therapy (deflazacort or prednisone), physiotherapy, monitoring motor milestones
Late Ambulatory	7–12 years	Progressive weakness in hip and thigh muscles, difficulty climbing stairs, reduced walking speed, increased fatigue	Continued corticosteroids, orthotic support, exon-skipping therapies where eligible, respiratory baseline testing
Early Non-Ambulatory	10–15 years	Loss of independent walking, upper limb weakness begins, early scoliosis, declining respiratory function	Power wheelchair, spinal bracing or surgery, non-invasive ventilatory support (BiPAP), cardiac monitoring
Late Non-Ambulatory	15+ years	Severe upper limb and respiratory muscle weakness, cardiomyopathy, dysphagia, high risk of respiratory infections	Assisted ventilation, ACE inhibitors or beta-blockers for cardiac care, nutritional support, palliative care planning
Advanced Care	Late teens–adulthood	Dependence on full-time ventilatory support, significant swallowing difficulties, complex cardiac involvement	Multidisciplinary team care through Canadian neuromuscular centres, advance care directives, psychosocial support

Muscular dystrophy is actually a group of more than 30 genetic conditions. All of them cause muscle weakness and progressive loss of muscle tissue. Duchenne muscular dystrophy (often called DMD) is the most severe and most common form.

In DMD, muscle fibres break down over time. Fatty and connective tissue gradually replaces healthy muscle. As a result, a child’s ability to move, breathe, and eventually maintain heart function becomes increasingly affected.

For more background on muscular dystrophy as a group of conditions, visit Health Canada’s chronic disease resources.

What Causes Duchenne Muscular Dystrophy?

The Role of Genetics

DMD is caused by a mutation in the gene responsible for producing a protein called dystrophin. This protein acts like a shock absorber inside muscle cells. It links the cell’s internal skeleton to the outer membrane, keeping the cell stable during muscle contractions.

When the dystrophin gene is deleted or duplicated, the body cannot produce this protein properly. Without dystrophin, the muscle cell membrane becomes fragile. It tears during normal muscle use, allowing calcium to flood into the cell. This triggers a chain reaction that destroys the muscle fibre from the inside.

How DMD Is Inherited

DMD follows an X-linked recessive inheritance pattern. This means the faulty gene sits on the X chromosome. Biological females carry two X chromosomes, so they can carry the mutation without usually showing symptoms. Biological males have only one X chromosome, so they develop the full disease if that chromosome carries the mutation.

About 30% of DMD cases are not inherited at all. They arise from a new, spontaneous gene mutation with no family history of the disease. Therefore, any family can be affected, even with no prior history of muscular dystrophy.

Learn more about how genetic conditions are inherited at the Mayo Clinic’s muscular dystrophy overview.

Recognising the Signs of Duchenne Muscular Dystrophy

Early Childhood Symptoms

Parents often notice the first signs of Duchenne muscular dystrophy when their son is between 3 and 4 years old. The child may seem clumsy or fall more often than other children. Motor milestones such as running, climbing stairs, or jumping may be delayed or difficult.

A classic early sign is the Gowers’ sign. When getting up from the floor, the child uses his hands to push up along his own legs. This happens because the muscles around the hips and thighs are already weakened. It is often one of the first clear clues that something is wrong.

Muscle Changes Parents May Notice

Interestingly, the calf muscles may look unusually large and firm in the early stages. This is called pseudohypertrophy. The calves appear bulky, but they are actually being filled with fat and scar tissue rather than healthy muscle. This creates a misleadingly strong appearance.

As DMD progresses, children often develop an exaggerated inward curve of the lower back, known as lordosis. The shoulder muscles and abdominal muscles also weaken over time. However, facial muscles and eye muscles are typically not affected, since they do not rely on dystrophin.

Later-Stage Complications

As a child with DMD grows older, the disease affects more of the body. Most boys with DMD require a wheelchair by their early teens. In addition, the heart muscle becomes affected, a condition called cardiomyopathy. This can lead to irregular heart rhythms and eventually heart failure.

Breathing muscles also weaken over time. Respiratory complications are a leading cause of serious illness in DMD. Furthermore, approximately one in three individuals with DMD experiences some degree of learning or intellectual difficulties. These are not related to muscle weakness but to the role dystrophin plays in brain tissue.

How Is Duchenne Muscular Dystrophy Diagnosed?

Initial Blood Tests

A family doctor or paediatrician will usually begin by ordering a blood test measuring creatine kinase (CK). This enzyme leaks into the bloodstream when muscle fibres break down. In DMD, CK levels can be 25 to 200 times higher than normal. This is often one of the earliest indicators of the disease, even before symptoms are obvious.

Further Testing

If CK levels are elevated, further testing is needed to confirm the diagnosis. An electromyography (EMG) test measures the electrical activity of muscles. In DMD, the results show abnormal patterns indicating muscle damage rather than nerve damage.

A muscle biopsy may also be performed. This involves taking a small sample of muscle tissue and examining it under a microscope. In early DMD, the sample will show some muscle fibres breaking down alongside early signs of repair. In later stages, fat and fibrous tissue replace much of the muscle.

An ELISA test can also measure the actual amount of dystrophin protein in a muscle sample, confirming the diagnosis. Genetic testing can identify the specific mutation in the dystrophin gene, which also helps with family planning and understanding the disease pattern.

Heart and Breathing Assessments

Once DMD is diagnosed, regular monitoring of heart and lung function becomes essential. An electrocardiogram (ECG) can detect characteristic changes in heart rhythm associated with DMD. Pulmonary function tests track breathing capacity over time. These are typically arranged through a specialist referral within your provincial health plan.

Treatment and Management in Canada

No Cure, But Meaningful Support

There is currently no treatment that stops or reverses Duchenne muscular dystrophy. However, a combination of therapies can slow the progression of symptoms and significantly improve daily life. Treatment is best managed through a multidisciplinary team, which many major Canadian children’s hospitals and neuromuscular disease centres offer.

Physiotherapy and Physical Activity

Regular physiotherapy is a cornerstone of DMD management. A physiotherapist works to maintain flexibility, prevent joint stiffness, and slow the development of muscle contractures. Contractures occur when muscles and tendons shorten permanently, limiting movement. Gentle stretching exercises are recommended regularly.

Low-impact physical activity, such as swimming, can also help maintain muscle strength and cardiovascular health for as long as possible. Your child’s care team can advise on appropriate activities based on their current abilities.

Orthopaedic and Surgical Interventions

As DMD progresses, orthopaedic support becomes increasingly important. Braces and orthotics can help maintain posture and mobility. In some cases, surgery is used to correct contractures or to stabilise the spine if scoliosis develops. These interventions help maintain independence and comfort.

Medications

Corticosteroids such as prednisone have been shown to temporarily slow muscle deterioration in some individuals with DMD. However, responses vary considerably from person to person. Some individuals experience meaningful benefit, while others may see side effects without clear improvement. Your specialist will weigh the risks and benefits carefully.

Other medications, including methotrexate and intravenous immunoglobulin, have been tried in some cases, but results have been inconsistent. Research into gene therapy and exon-skipping treatments is ongoing and showing promise, though these are not yet widely available through standard provincial coverage in Canada.

Heart and Respiratory Care

Medications to support heart function, such as ACE inhibitors or beta-blockers, are often prescribed once cardiac changes appear. Breathing support, including non-invasive ventilation at night, can be introduced as respiratory muscles weaken. These measures are typically coordinated through paediatric cardiology and respirology specialists.

You can find additional information about ongoing DMD research through Healthline’s guide to Duchenne muscular dystrophy.

When to See a Doctor

If you notice that your son is falling frequently, struggling to climb stairs, rising from the floor in an unusual way, or lagging behind other children in physical development, speak with your family doctor as soon as possible. These signs do not always mean DMD, but they deserve prompt medical attention.

Your family doctor can order initial blood tests and refer you to a paediatric neurologist or neuromuscular specialist. If you cannot reach your family doctor quickly, a walk-in clinic can begin the initial assessment and arrange urgent referrals. Early diagnosis allows for earlier access to therapies that can make a meaningful difference in your child’s life.

Families affected by DMD in Canada can also connect with provincial neuromuscular disease programmes for coordinated, multidisciplinary care. Ask your doctor or specialist about resources available in your province. Always consult a qualified healthcare provider before making any decisions about diagnosis or treatment.

Frequently Asked Questions About Duchenne Muscular Dystrophy

Key Takeaways

• Duchenne muscular dystrophy is the most common inherited muscle disease in boys, affecting roughly 1 in 3,500 to 4,500 male births.
• It is caused by a missing or faulty dystrophin protein, which leads to progressive breakdown of muscle fibres throughout the body.
• Early signs include frequent falls, difficulty climbing stairs, and using the hands to push up from the floor (Gowers’ sign).
• The disease eventually affects the heart and breathing muscles, making ongoing specialist monitoring essential.
• There is no cure, but physiotherapy, medications, and cardiac and respiratory support can slow progression and improve quality of life.
• If you notice signs of muscle weakness or delayed motor development in your child, speak with your family doctor or visit a walk-in clinic promptly.
• Canadians can access multidisciplinary neuromuscular care through children’s hospitals and specialist referrals under provincial health plans.
• Always consult a qualified healthcare professional for diagnosis and treatment guidance specific to your child’s needs.