Diagnosed between 2 and 7 years old. Parents and pediatricians note that delays occur in the development goals as sitting, walking and / or speak in the language and / or inability to stay within the parameters of their age mates, they will be the first signs of disease. In addition to these signs, there are currently reliable laboratory studies to help doctors diagnose a child with Duchenne. The following tests are commonly used to confirm a preliminary diagnosis of Duchenne: The study of muscle enzymes.