What is Duchenne muscular dystrophy? Duchenne muscular dystrophy is a muscle-wasting condition caused by the lack of a protein called dystrophin. It usually affects only boys. About 100 boys with Duchenne muscular dystrophy are born in the UK each year and there are about 2,500 boys and young men known to be living with the condition in the UK at any one time. For the general population, the risk of having a child with Duchenne muscular dystrophy is about one in every 3,500-5,000 male births.