Duchenne muscular dystrophy

Flexion contracture

People with duchenne muscular dystrophy may develop joint contractures, where a joint becomes tight and stiff and cannot fully straighten or bend.

Calf muscle pseudohypertrophy

Enlarged-looking calves (calf pseudohypertrophy) are characteristic; the muscle is being replaced by fat and fibrous tissue rather than being strong.

Calf muscle hypertrophy

The calf muscles often look enlarged (calf pseudohypertrophy). This is because muscle is gradually replaced by fat and scar tissue, not because of added strength.

Elevated circulating creatine kinase activity

A markedly raised blood level of creatine kinase (CK), an enzyme released from damaged muscle, is an early clue and is often very high in this condition.

Childhood onset

Duchenne is a childhood-onset muscular dystrophy. It is usually recognized in boys in early childhood.

Loss of ambulation

Walking ability is gradually lost, on average in the early teens, after which a wheelchair is needed.

Obstructive sleep apnea

Younger people with duchenne muscular dystrophy can have pauses in breathing during sleep caused by a blocked airway (obstructive apneas). This risk is linked to weight gain that follows reduced physical activity and long-term corticosteroid treatment.

Mild intellectual disability

Because dystrophin is also active in the brain, some boys with Duchenne have learning or cognitive difficulties, which can be mild and vary widely between individuals.

Delayed gross motor development

Reaching motor milestones late, such as sitting, standing, or walking, is a common early sign of Duchenne.

Dilated cardiomyopathy

The heart muscle is also affected over time, leading to a dilated cardiomyopathy that needs regular monitoring.

Congestive heart failure

If the heart muscle weakens enough, it can lead to heart failure, where the heart cannot pump blood as effectively as the body needs.

Cardiomyopathy

Dystrophin is also needed by the heart muscle. Over time many people with Duchenne develop a weakened, enlarged heart (dilated cardiomyopathy), so heart monitoring is part of routine care.

Arrhythmia

In duchenne muscular dystrophy the heart can develop abnormal rhythms, both in the upper chambers (atrial) and lower chambers (ventricular). These arrhythmias tend to appear later in the course of the condition.

X-linked recessive inheritance

Duchenne muscular dystrophy is inherited in an X-linked recessive pattern, which is why it predominantly affects boys, with the gene change carried on the X chromosome.

Hypoventilation

In duchenne muscular dystrophy, breathing during sleep can become too shallow or slow, so the body takes in less oxygen and clears less carbon dioxide. This under-breathing is called hypoventilation.

Respiratory failure

As the muscles used for breathing weaken, breathing support becomes increasingly important, and respiratory failure is a serious later complication.

Muscle weakness

Progressive weakness of the muscles closest to the trunk (hips, thighs, shoulders) usually appears in early childhood and is the core feature.

Respiratory insufficiency due to muscle weakness

As duchenne muscular dystrophy progresses, the muscles used for breathing, especially the diaphragm, weaken. This weakness can make breathing inadequate, so oxygen levels fall, particularly in older people with the condition.

Difficulty climbing stairs

Weakness in the muscles closest to the hips and shoulders makes activities like climbing stairs and getting up from the floor difficult.

Hypotonia

Young children with Duchenne can have low muscle tone (hypotonia), meaning the muscles feel floppy and provide less support than expected for their age.

Gowers sign

A 'Gowers sign', using the hands to push up the legs when rising from the floor, is a classic early sign of the hip and thigh weakness.

Scoliosis

As trunk muscles weaken, the spine can curve sideways (scoliosis), particularly after a child stops walking.

Duchenne muscular dystrophy

Diagnosed using: Serum creatine kinase (CK).

Duchenne muscular dystrophy

Diagnosed using: Genetic testing for DMD.

Duchenne muscular dystrophy

Diagnosed using: Echocardiography.

Glucocorticoids

Glucocorticoids (corticosteroids such as prednisone or deflazacort) are the mainstay of treatment and can slow the loss of muscle strength, though they carry significant side effects.

Used to help with: Duchenne muscular dystrophy.

Exon-skipping therapy

Exon-skipping medicines help some people with Duchenne make a partially working dystrophin protein. They only help those whose specific mutation matches the targeted exon (currently exons such as 51, 53, and 45), so eligibility depends on a person's exact DMD mutation.

Used to help with: Duchenne muscular dystrophy.

Assisted ventilation

Assisted ventilation is breathing support used in duchenne muscular dystrophy as breathing muscles weaken. It usually starts at night, and daytime support is added as respiratory failure progresses.

Used to help with: Respiratory failure.