Duchenne muscular dystrophy
Duchenne muscular dystrophy is an inherited disorder that involves muscle weakness, which quickly gets worse.
Pseudohypertrophic muscular dystrophy; Muscular dystrophy - Duchenne type
Duchenne muscular dystrophy is a form of muscular dystrophy. It worsens quickly. Other muscular dystrophies (including Becker's muscular dystrophy) get worse much more slowly.
Duchenne muscular dystrophy is caused by a defective gene for dystrophin (a protein in the muscles). However, it often occurs in people without a known family history of the condition.
Because of the way the disease is inherited, it usually affects boys. The sons of females who are carriers of the disease (women with a defective gene, but no symptoms themselves) each have a 50% chance of having the disease. The daughters each have a 50% chance of being carriers. Very rarely, a girl can be affected by the disease.
Duchenne muscular dystrophy occurs in about 1 out of every 3,600 male infants. Because this is an inherited disorder, risks include a family history of Duchenne muscular dystrophy.
Symptoms usually appear before age 6 and may appear as early as infancy.
They may include:
- Learning difficulties (the IQ can be below 75)
- Intellectual disability (possible, but does not get worse over time)
- Begins in the legs and pelvis, but also occurs less severely in the arms, neck, and other areas of the body
- Problems with motor skills (running, hopping, jumping)
- Frequent falls
- Trouble getting up from a lying position or climbing stairs
- Weakness quickly gets worse
Progressive difficulty walking:
- Ability to walk may be lost by age 12, and the child will have to use a wheelchair
- Breathing difficulties and heart disease usually start by age 20
Exams and Tests
A complete nervous system (neurological), heart, lung, and muscle exam may show:
- Abnormal heart muscle (cardiomyopathy)
- Congestive heart failure or irregular heart rhythm (arrhythmia)
- Deformities of the chest and back (scoliosis)
- Enlarged muscles of the calves, buttocks, and shoulders (around age 4 or 5). These muscles are eventually replaced by fat and connective tissue (pseudohypertrophy).
- Loss of muscle mass (wasting)
- Muscle contractures in the heels, legs
- Muscle deformities
- Respiratory disorders, including pneumonia and swallowing with food or fluid passing into the lungs (in late stages of the disease)
Tests may include:
- Electromyography (EMG)
- Genetic tests
- Muscle biopsy
- Serum CPK
There is no known cure for Duchenne muscular dystrophy. Treatment aims to control symptoms to improve quality of life.
Steroid drugs can slow the loss of muscle strength. They may be started when the child is diagnosed or when muscle strength begins to decline.
Other treatments may include:
- Albuterol--a drug used for people with asthma
- Amino acids
- Coenzyme Q10
- Fish oil
- Green tea extracts
- Vitamin E
However, the effects of these treatments have not been proven. Stem cells and gene therapy may be used in the future.
Activity is encouraged. Inactivity (such as bedrest) can make the muscle disease worse. Physical therapy may help to maintain muscle strength and function. Speech therapy is often needed.
Other treatments may include:
- Assisted ventilation (used during the day or night)
- Drugs to help heart function, such as angiotensin-converting-enzyme inhibitors, beta-blockers, and diuretics
- Orthopedic appliances (such as braces and wheelchairs) to improve mobility
- Proton pump inhibitors (for people with gastroesophageal reflux)
Several new treatments are being studied in trials.
You can ease the stress of illness by joining a support group where members share common experiences and problems. The Muscular Dystrophy Association is an excellent source of information on this disease.
Duchenne muscular dystrophy leads to progressively worsening disability. Death usually occurs by age 25, typically from lung disorders.
- Cardiomyopathy (can also occur in female carriers, who should also be screened)
- Congestive heart failure (rare)
- Heart arrhythmias (rare)
- Mental impairment (varies, usually minimal)
- Permanent, progressive disability, including decreased mobility and decreased ability to care for self
- Pneumonia or other respiratory infections
- Respiratory failure
When to Contact a Medical Professional
Call your health care provider if:
Your child has symptoms of Duchenne muscular dystrophy
Symptoms worsen, or new symptoms develop, particularly fever with cough or breathing difficulties
People with a family history of the disorder may want to seek genetic counseling. Genetic studies done during pregnancy are very accurate in detecting Duchenne muscular dystrophy.
Sarnat HB. Muscular dystrophies. In: Kliegman RM, Stanton BF, St. Geme J, Schor N, Behrman RE. Nelson Textbook of Pediatrics. 19th ed. Philadelphia, PA: Saunders Elsevier; 2011:chap 601.