What Is Duchenne Muscular Dystrophy? Expand Duchenne muscular dystrophy or DMD is a genetic (inherited) disorder that causes muscle weakness and wasting. The muscle weakness starts in early childhood and symptoms are usually first noticed between the ages of 2 and 5 years. The weakness mainly affects the ‘proximal’ muscles which are those near the trunk of the body, around the hips and shoulders, and so the first signs are often when the child has difficulty getting up from the floor, walking or running. The weakness progresses through childhood and adolesence eventually affecting all the muscles used for moving and also those used for breathing and the heart muscle as well. Duchenne affects approximately 1 in every 3500 new born boys and is found in children in all countries and cultures. Very rarely it can also affect girls. In the UK there are around 2500 boys and young men with Duchenne. The name Duchenne comes from the doctor who first described the condition. In general, a steady decline in muscle strength between the ages of 6 and 11 is expected and by 12 years many children are confined to a wheelchair. By their late teens most young people with Duchenne lose the ability to move their arms and experience more problems with breathing and with the heart. Those with Duchenne do have shortened lives, it is unusual for someone with Duchenne to live beyond their 30s. However, advances in management of the condition are increasing life expectancy and enabling more young adults with Duchenne to lead independent lives. There are other types of muscular dystrophy and the different types vary as to how severe the muscle weakness is and how quickly it progresses. Becker muscular dystrophy or BMD is similar to Duchenne but less severe with symptoms starting in the teenage years or early twenties.