Becker Muscular Dystrophy (BMD)
Age of onset
2 to 16 years
Similar to Duchenne MD, but less severe. They include general muscle weakness, especially in the upper leg and arms, and pelvic muscles. Calf muscles are generally hypertrophic (bigger than usual). Heart problems are also possible
Rate of Progression
Slower than Duchenne MD
X-linked recessive. BMD primarily affects young males, who inherit the condition through their mothers. Women can be carriers but usually exhibit no symptoms, because the dystrophin gene is located on the X chromosome – of which women have 2 copies – and one functioning copy of the dystrophin gene is generally sufficient for normal muscle function.