<qa>  What is the cause of the disease?Duchenne muscular dystrophy DMD is a progressive devastating disease that affects mainly boys, with an incidence of about 1:3,500 live births. The pathology of DMD is a result of non-repaired muscle damage that leads to muscle-tissue replacement by scar tissue, a process known as fibrosis. Currently, there is no effective treatment for the disease. The only therapy offered to these boys are steroids which slightly delayed the disease progression. The boys lose their ability to walk at around the age of 12, and die in the 4th decade of life from severe heart and lung problems. 