Key facts

• Inheritance: X-linked recessive, so it mainly affects boys. Some female carriers can have muscle weakness or heart involvement.
• Onset: usually early childhood, often age 2 to 5 years.
• Typical features:
  • Delayed walking and frequent falls
  • Difficulty running, climbing stairs, or rising from the floor
  • Gowers sign: using the hands to push up on the thighs when standing
  • Waddling gait and enlarged-looking calves, called calf pseudohypertrophy
  • Progressive loss of muscle strength
  • Later scoliosis, breathing muscle weakness, and cardiomyopathy

Diagnosis

• Blood creatine kinase (CK) is usually very high, often more than 10 times the upper limit of normal.
• Confirmation is by genetic testing showing a DMD-gene variant. The exact variant also helps determine whether mutation-specific therapies may be suitable.
• Muscle biopsy is now generally reserved for uncommon cases where genetic testing is not definitive.
  Tietz Textbook of Laboratory Medicine, 7th Edition, pp. 254-258.

Treatment and care

• Corticosteroids such as prednisone/prednisolone or deflazacort can preserve strength and prolong walking ability.
• Regular physiotherapy, stretching, orthoses, mobility support, and prevention or management of contractures and scoliosis.
• Regular heart monitoring, often with echocardiography or cardiac MRI. ACE inhibitors, beta-blockers, and other heart medicines may be used if cardiomyopathy develops.
• Regular lung-function assessment, vaccinations, cough support, and non-invasive ventilation when needed.
• Assessment for learning, speech, psychological, nutrition, and bone-health needs.
• Some patients may be eligible for variant-specific exon-skipping therapies or gene-based therapies, depending on country, age, clinical status, and genetic result.