People diagnosed with neuromuscular disorders undergo muscle deterioration that worsens as they grow older. This is the same with DMD patients, with the only difference being the speed at which their muscles degrade. Duchenne Muscular Dystrophy causes symptoms to worsen extremely quickly,as it's symptoms can appear while the patient is still in their infancy.
During the disorder's early stages, the legs and pelvis are the first areas to deteriorate severely. The other muscles within the body start to deteriorate slowly as well. Many toddlers with DMD will also experience pseudohypertrophy in their calves, which is when a muscle experiences an increase in mass and size due to abnormal growth and the buildup of scar tissue. (DMD - Signs and Symptoms, 2015) Due to all of this, the affected child will have balance issues and will have extreme difficulty with walking, running, jumping, etc. As they grow older, they will eventually gain additional habits to make up for their muscle weaknesses such as walking on their tip toes, sticking out their stomach and pulling back shoulders to maintain balance, and having difficulty in raising their arms. By age 12, it is highly likely that they will lose their ability to walk altogether, thus resulting in them needing a powered wheelchair.
Later on in life, they will start to develop more life threatening symptoms. The myocardium layer of the heart will also start to deteriorate over time. This is primarily due to the fact that this layer is made up of muscle. This would eventually lead to the patient developing a disease known as cardiomyopathy, which occurs when the heart is having difficulty pumping blood throughout the body due to abnormalities in the myocardium. This in turn may also lead to heart failure, and potentially death. Muscles in the lungs and diaphragm also deteriorate with all the other muscles. This would make it hard for the affected person to get oxygen efficiently, causing them to have frequent migraines. These issues can start as early as age 20, which means that DMD patients also suffer from a reduced lifespan. At this day and age, people with DMD usually live to their early thirties. (Haldeman-Englert, 2014)
DMD also has an effect on the person's cognitive ability as well. According to the Muscular Dystrophy Association, "about a third of boys with DMD have some degree of learning disability" ("Signs and Symptoms", 2015) In some cases, their intellectual abilities can be extremely poor, as some patient's IQ can be below 75. It is believed that there is a link between dystrophin levels and cognitive abilities, thus causing those with abnormal levels of said protein to have issues with learning.
Background Image 5. A DMD child using a powered wheelchair in order to manoeuvre around. DMD Boy [Digital image]. (n.d.). Retrieved April 12, 2016, from http://musculardystrophynews.com/wp-content/uploads/2014/12/DMD-boy.jpg