Muscular dystrophy (MD) is a group of inherited muscle diseases in which muscle fibers are unusually susceptible to damage. Muscles, primarily voluntary muscles, become progressively weaker. In the late stages of muscular dystrophy, fat and connective tissue often replace muscle fibers. Some types of muscular dystrophy affect heart muscles, other involuntary muscles and other organs.
The most common types of muscular dystrophy appear to be due to a genetic deficiency of the muscle protein dystrophin.
There's no cure for muscular dystrophy, but medications and therapy can slow the course of the disease.
Signs and symptoms vary according to the type of muscular dystrophy. In general, muscular dystrophy symptoms may include:
Specific signs and symptoms vary among the different forms of MD. Each type is different in the age of onset, which parts of the body the symptoms primarily affect and how rapidly the disease progresses.
Duchenne's muscular dystrophy is the most severe form of dystrophinopathy. It occurs mostly in young boys and is the most common form of MD that affects children. Signs and symptoms of Duchenne's MD may include:
Signs and symptoms of Duchenne's usually appear between the ages of 2 and 3. It first affects the muscles of the pelvis, upper arms and upper legs. By late childhood, most children with this form of muscular dystrophy are unable to walk. Most die by their 20s or early 30s, often from pneumonia, respiratory muscle weakness or cardiac complications. Some people with Duchenne's MD may exhibit curvature of their spine (scoliosis).
Becker's muscular dystrophy is a milder form of dystrophinopathy. It generally affects older boys and young men, and progresses more slowly, usually over several decades. Signs and symptoms of Becker's MD are similar to those of Duchenne's. The onset of the signs and symptoms is generally around age 11, but may not occur until the mid-20s or even later. Those affected by Becker's MD usually are able to walk through their teens, and often well into adulthood.
Although this form of MD can affect children, it often doesn't affect people until adulthood. It can vary greatly in its severity. Muscles may feel stiff after using them. Progression of this form of MD is slow. Besides myotonia, signs and symptoms of adult-onset myotonic dystrophy may include:
Rarely, infants have this form of muscular dystrophy, in which case it's called congenital myotonic dystrophy. The infant form is more severe, although infants with myotonic dystrophy don't experience myotonia. Signs in infants may include:
Facioscapulohumeral muscular dystrophy
When someone with facioscapulohumeral MD raises his or her arms, the shoulder blades may stick out like wings. Progression of this form is slow, with some spurts of rapidly increasing weakness. Onset usually occurs during the teen to early adult years.
Other major types of muscular dystrophy
Limb-girdle muscular dystrophy
This form then progresses to the arms and legs, though progression is slow. Limb-girdle MD may begin from early childhood to adulthood.
Congenital muscular dystrophy
Congenital MD is apparent at birth or becomes evident before age 2. The course of this disorder varies significantly depending on the type. Some forms of congenital MD progress slowly and cause only mild disability, while others progress rapidly and cause severe impairment.
Oculopharyngeal muscular dystrophy
Distal muscular dystrophy
Emery-Dreifuss muscular dystrophy
Cardiac arrhythmias, stiffness of the spine and muscle contractures are other features of Emery-Dreifuss MD. Emery-Dreifuss MD usually begins in the childhood to early teen years and progresses slowly.
Myofibrillar myopathies (MFMs)
When to see a doctor
A child with MD may learn to walk later than other children do and may exhibit signs of muscle weakness between the ages of 2 and 6. By school age, a child with MD may walk unsteadily and on the toes or balls of the feet. Duchenne's MD usually results in children losing the ability to walk by age 12.
See your doctor if you're concerned about your child's:
Once muscular dystrophy is diagnosed, medications and physical therapy can help slow its progression.
Because muscular dystrophies are inherited disorders, genetic counseling may be helpful if you're considering having children and to assess the risk of the disease in other family members.
Muscular dystrophy is a general term for a group of inherited diseases involving a defective gene. Each form of muscular dystrophy is caused by a genetic mutation that's particular to that type of the disease. The most common types of muscular dystrophy appear to be due to a genetic deficiency of the muscle protein dystrophin.
Inheriting Duchenne's or Becker's MD
The defective gene that causes Duchenne's and Becker's muscular dystrophies is located on the X-chromosome. Women who have only one X-chromosome with the defective gene that causes these muscular dystrophies are carriers and sometimes develop heart muscle problems (cardiomyopathy) and mild muscle weakness. The disease can skip a generation until another son inherits the defective gene on the X-chromosome. In some cases of Duchenne's and Becker's muscular dystrophies, the disease arises from a new mutation in a gene rather than from an inherited defective gene.
Patterns differ for other types of MD
Some of the less common types of muscular dystrophy are passed along in the same inheritance pattern that marks Duchenne's and Becker's muscular dystrophies. Other types of muscular dystrophy can be passed on from generation to generation and affect males and females equally. Still others require a defective gene from both parents.
X-linked recessive inheritance pattern with carrier mother
Women can pass down X-linked recessive disorders such as Duchenne's muscular dystrophy. A woman who is a carrier of an X-linked recessive disorder has a 25 percent chance of having an unaffected ...
Autosomal dominant inheritance pattern
In an autosomal dominant disorder, the mutated gene is a dominant gene located on one of the nonsex chromosomes (autosomes). You only need one mutated gene to be affected by this type of ...
Preparing for your appointment
Call your doctor if your baby or child develops problems with strength or coordination, isn't reaching expected developmental milestones, or has any other signs or symptoms common to muscular dystrophy. After your initial appointment, you may be referred to a doctor who specializes in the diagnosis and treatment of conditions that affect the brain and nervous system (neurologist).
Here's some information to help you get ready for your appointment, and what to expect from your doctor.
What you can do
Questions to ask your child's doctor at the initial appointment include:
Questions to ask if you're referred to a specialist include:
In addition to the questions that you've prepared to ask your doctor, don't hesitate to ask questions during your appointment at any time that you don't understand something.
What to expect from your doctor
What you can do in the meantime
Tests and diagnosis
A careful review of your family's history of muscle disease can help your doctor reach a diagnosis. In addition to a medical history review and physical examination, your doctor may rely on the following in diagnosing muscular dystrophy:
Treatments and drugs
There's currently no cure for any form of muscular dystrophy. Research into gene therapy may eventually provide treatment to stop the progression of some types of muscular dystrophy. Current treatment is designed to help prevent or reduce deformities in the joints and the spine and to allow people with MD to remain mobile as long as possible. Treatments may include various types of physical therapy, medications, assistive devices and surgery.
One goal of physical therapy is to provide regular range-of-motion exercises to keep your joints as flexible as possible, delaying the progression of contractures, and reducing or delaying curvature of your spine. Using hot baths (hydrotherapy) also can help maintain range of motion in joints.
Coping and support
For family members of people with muscular dystrophy, coping with the illness involves a major commitment of physical, emotional and financial effort. The disease presents challenges in the classroom, in the home and in all aspects of life.
In dealing with a disease such as muscular dystrophy, support groups can be a valuable part of a wider network of social support that includes health care professionals, family, friends and a place of religious worship.
Support groups bring together people, family and friends who are coping with the same kind of physical or mental health challenge. Support groups provide a setting in which people can share their common problems and provide ongoing support to one another.
Ask your doctor about self-help groups that may exist in your community. Your local health department, public library, telephone book and the Internet also may be good sources to locate a support group in your area.
Last Updated: 2009-12-08
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