What are Duchenne and Becker muscular dystrophies (MD)?
MD are a group of muscle diseases that have three features in common: they run in families (are hereditary), they get worse over time, and each causes a characteristic pattern of muscle weakness. Duchenne and Becker MD cause similar patterns of weakness and disability and are inherited in the same way. Both are due to a problem with the same gene on the X chromosome. This gene normally makes a protein called dystrophin. People with Duchenne and Becker MD have less dystrophin in their muscles than normal. Becker MD is like a milder form of Duchenne MD, with less severe weakness. All forms of MD are considered rare, but Duchenne MD is the most common. Duchenne MD affects approximately 1 boy in every 3,000 and Becker MD occurs in about 1 in 18,000 births.
