Duchenne muscular dystrophy (DMD) is the most common fatal genetic disorder diagnosed in early childhood (about 20,000 new cases each year). It occurs across all races and cultures, and it is caused by a mutated gene found on the X-chromosome that encodes for dystrophin (a protein that helps maintain the structure of muscle cells). Duchenne can be passed down from a mother to a child, or it can happen because of a random spontaneous mutation in families with no history of DMD. Thus, ANYONE can have a child with Duchenne. It primarily affects boys, but there are cases of females with DMD. Usually, children with Duchenne lose their ability to walk and need a wheelchair between the ages of 8 and 10. By their late teens, they lose their upper body strength including the use of their arms and eventually need a respirator to help them breath. Young Duchenne patients typically live into their twenties or early thirties because the progressive muscle weakness leads to serious medical problems, particularly issues relating to the heart and lungs.