Duchenne muscular dystrophy

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X-linked recessive genetic defects

X-linked recessive genetic defects - how boys are affected

X-linked recessive genetic defects - how girls are affected

Pseudohypertrophic muscular dystrophy; Muscular dystrophy - Duchenne type

• Muscle weakness
  • Rapidly progressive
  • Frequent falls
  • Difficulty with motor skills (running, hopping, jumping)
• Progressive difficulty walking
  • Ability to walk may be lost by age 12
• Fatigue
• Intellectual retardation (possible)
• Skeletal deformities
  • Chest and back (scoliosis)
• Muscle deformities
  • Contractures of heels, legs
  • Pseudohypertrophy of calf muscles

Muscle wasting (atrophy) begins in the legs and pelvis, then progresses to the muscles of the shoulders and neck, followed by loss of arm muscles and respiratory muscles. Calf muscle enlargement (pseudohypertrophy) is quite obvious.

Cardiomyopathy is commonly present, but signs of congestive heart failure or arrhythmias (irregular heartbeats) are rare. Respiratory disorders are common during the later stages, including pneumonia and aspiration of food or fluid into the lungs.

• A serum CPK is highly elevated.
• A neurological exam shows weakness and lack of coordination or balance.
• An EMG (electromyography) shows that weakness is caused by destruction of muscle tissue, rather than nerve damage.
• A muscle biopsy confirms the diagnosis.

Review Date: 08/11/2006
Reviewed By: Brian Kirmse, MD, Mount Sinai School of Medicine, Department of Human Genetics, New York, NY. Review provided by VeriMed Healthcare Network.