Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD) can have the same symptoms and are caused by mutations in the same gene. BMD symptoms can begin later in life and be less severe than DMD. However, because these two kinds are very similar, they are often studied and referred to together (DBMD).

How many people are affected?
About 14 in 100,000 males 5 – 24 years of age

Who is more likely to be affected: males or females?
Males

When does muscle weakness typically begin?
DMD symptoms usually begin before 5 years of age. In BMD, symptoms usually appear later, even into adulthood.

Which parts of the body show weakness first?
Upper legs and upper arms

What other parts of the body can be affected?
Heart, lungs, throat, stomach, intestines, and spine

• Abnormally developed bones, leading to deformities of the chest and back (scoliosis)
• Abnormality of heart muscle function (cardiomyopathy)
• Congestive heart failure or irregular heartbeat (arrhythmias)
• Muscle deformities
  • Contractures of heels and legs
  • Fat and connective tissue (pseudohypertrophy) in calf muscles
• Muscle wasting that begins in the legs and pelvis, then progresses to the muscles of the shoulders, neck, arms, and respiratory system

• CPK
• Electromyography (EMG)
• Muscle biopsy or genetic testing