Disease Progression in DMD

In DMD, the muscle breaks down and is replaced by fat and scar tissue, leading to an increasing loss of muscle function.6,8 In the early stages of Duchenne, the disease primarily affects the muscles of the hips and thighs. This leads to difficulty standing, climbing stairs, and maintaining balance.4,9

As the disease progresses, it affects the muscles in the shoulders and arms, leading to functional difficulties such as raising the arms.

Additional muscles in the legs and trunk are also affected, as are those of the diaphragm and heart.12 The rate of progression varies from child to child.

Note that the graphics show typical clinical and biological signs of DMD at various approximate age ranges. Also, DMD is a heterogeneous disease, and each child may progress differently.

0 to 4 years4,6,8,9,11

  • Inflammation soon after birth
  • Muscle fibrosis seen as early as 1 year old
  • Motor delays
  • Other delays, eg, speech

5 to 7 years4,12-15

  • Progressive muscle weakness
  • Enlarged calves
  • Toe walking
  • Standing-from-supine difficulty
  • Fat accumulation in muscle

8 to 11 Years4,12-15

  • Motor milestone delays
  • Decreased walking ability
  • Part-time wheelchair use

12 to 19 Years4,13-15

  • Decreased upper limb, respiratory, and cardiac function
  • Loss of ambulation
  • Ventilatory support often required
  • Unable to perform activities of daily living (ADL)

Teens and beyond13-15

  • Increasing cardiac dysfunction
  • Heart failure
  • Life expectancy severely reduced