Characteristics of DMD

Duchenne muscular dystrophy (DMD) is one of nine types of muscular dystrophy. DMD is an inherited muscle disorder occurring in early childhood that causes rapid degeneration of the muscles over a short period. The disorder also causes degeneration of the lungs and heart, making breathing difficult as the disorder progresses.

Symptoms

• Duchenne muscular dystrophy symptoms appear in a child around the age of 6 years or earlier. The symptoms include fatigue and muscle weakness. Walking will become difficult and many times the ability will be lost by the age of 12 years. Muscle weakness starts in the legs and pelvis and will affect motor skills and cause frequent falls. The muscle weakness will worsen quickly. Mental retardation is possible and may advance as the disorder progresses.

Cause

• A defective dystrophin gene is the cause of DMD. Dystrophin is a protein in the muscle that works to keep the muscle intact. While the disorder is inherited, it is common in people where there is no known history of the disease. The disease is more common in boys than girls, as it is an X-linked recessive disorder. According to the University of Maryland School of Medicine website, DMD will affect 1 in 3,600 infant boys. Male children of women who are carriers of the disorder have a 50 percent chance of developing DMD. DMD eventually affects all muscle groups including the heart and lungs.

Diagnosis

• A diagnosis is made following the appearance of symptoms. An electromyography test evaluates the health of the muscles and nerves controlling the muscles. The test involves injecting a needle electrode into the muscle. A muscle biopsy is conducted to check for muscle disorders and involves using a needle to take a sample of the muscle. The heart and lungs are also tested to evaluate the extent of the disease.

Treatment

• DMD causes muscle degeneration that is noncurable. Treatment for the disorder involves improving the quality of life for the patient. Activity and physical therapy are the primary treatments, as they encourage muscle movement. Bed rest or confinement decreases the muscle capability. Braces on the legs and wheelchairs are used once the muscle weakness becomes severe. It is rare for survival after the age of 30 years.

Prevention

• There is no way to prevent a newborn from developing DMD; however, genetic counseling will evaluate the risk based on genetic and family history. The testing is completed during pregnancy.