Duchenne muscular dystrophy (DMD)

Overview

Duchenne muscular dystrophy (DMD) is a progressive genetic condition in which the body cannot make dystrophin, a protein essential for muscle strength and structure. It mainly affects boys, usually becomes apparent in early childhood, leads to loss of mobility over time, and eventually affects the heart and breathing muscles — which is why it needs proactive, whole-body management rather than a narrow focus on muscle strength alone.

Symptoms

Weakness typically starts in the pelvis, hips and thighs before spreading to the shoulders and upper arms. Early signs include difficulty with stairs, running, jumping, or getting up off the floor (often using a distinctive technique called a Gower's manoeuvre, 'climbing up' the legs with the hands), and calves that look unusually large (pseudohypertrophy) as muscle is gradually replaced by fat and connective tissue. Many children need a wheelchair somewhere between ages 8 and 11, and fine motor tasks like writing or eating become harder as weakness progresses. Over time the heart, respiratory system and other organs become involved, and some children experience learning or behavioural difficulties alongside the physical symptoms.

Inheritance

DMD follows an X-linked recessive pattern, so it mainly affects boys, who have only one X chromosome; girls, with two X chromosomes, are usually unaffected carriers, though a minority of carriers ('manifesting carriers') develop some muscle weakness themselves. An affected man can't pass DMD to his sons, but every daughter will carry the changed gene.

Getting a diagnosis

Diagnosis is typically made around age 3. A GP refers to a specialist, and a blood test showing raised creatine kinase (CK) usually prompts genetic testing to confirm the specific dystrophin gene change. Genetic counselling for the wider family is generally arranged alongside diagnosis.

Management and outlook

Corticosteroids (prednisone or deflazacort) are a mainstay of treatment, slowing the progression of weakness; vamorolone is a newer alternative with a milder side-effect profile. Care works best through a genuinely multidisciplinary team — neurology, physiotherapy, occupational therapy, and specialists in respiratory, cardiac, endocrine, nutritional, orthopaedic and psychological care all have a role. Physiotherapy helps maintain movement and strength; cardiac care includes regular monitoring and medications such as ACE inhibitors; respiratory care includes sleep studies and non-invasive ventilation as needed; bone health is supported with vitamin D and yearly monitoring; and contractures and scoliosis are managed with orthopaedic input. Swallowing and gut symptoms benefit from specialist support, and psychological support matters throughout, not just at diagnosis. Newer, more targeted treatments — such as Translarna for specific genetic changes — are also available for eligible patients.