Duchenne muscular dystrophy (DMD) is the most common of the more than 30 types of muscular dystrophy. It is a genetic disease that leads to progressive deterioration of muscle fibers. The condition usually affects boys only but girls can also carry the mutated gene and experience some symptoms. They have a 50 percent risk of passing the mutated gene on to their sons, who will be affected by the disease.
DMD, an incurable disease, occurs in roughly one of every 3,500 male births. Symptoms typically begin to appear between ages 1 and 6, and muscle strength and function gradually decline over time. Current research has led to several innovative treatments that can slow progression of Duchenne and control its symptoms.
How does DMD affect the body?
DMD is caused by a genetic mutation in the DMD gene, which gives the instructions necessary to produce a protein called dystrophin. Dystrophin provides structural support and protection for muscle fibers. In DMD patients, a mutation in this gene prevents the body from making dystrophin, leaving the muscle fibers open to potential damage every time a muscle is used.
Symptoms in toddlers usually begin with weakening of muscles in the shoulders, hips and pelvic regions. They have difficulty standing up, running and jumping. As the condition develops, other muscles — including those in the arms, legs and trunk — begin to show indications of damage. At this point, children’s calves become enlarged, due to excessive scar tissue building up in the muscle. The disease can affect the heart, as well as the muscles that control breathing, as early as the teenage years.
How is DMD diagnosed?
Physicians suspecting DMD, based on the physical symptoms they see in the child, may request blood tests to look for indicators of muscle damage. Such tests typically measure levels of creatine kinase — an enzyme released from damaged muscles — in the bloodstream.
Physicians may also suggest genetic testing to look for specific mutations in the dystrophin gene. Relatives may also get tested to determine if they are carriers of the disease. Doctors may also perform a muscle biopsy to physically look for the presence of the dystrophin protein.
How is DMD treated?
Although DMD currently has no cure, treatments can slow muscle degradation. Doctors usually recommend physical activity and physiotherapy to counteract increasing muscle weakness, as well as braces and wheelchairs to keep patients mobile. Corticosteroids are also prescribed to strengthen muscles, though such drugs often have detrimental side effects. New and innovative therapies, such as exon skipping, show hope of possibly reversing some negative effects of DMD. Many of these therapies are still being tested in clinical trials.
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