Muscular Dystrophy

What are muscular dystrophies (MD)?
The muscular dystrophies (MD) are a diverse group of genetically determined (inherited) disorders primarily affecting the muscles of the body. Most tend to be progressive, but the rate of disease progression differs based on the specific type. They typically result from an ongoing breakdown of the muscle due to an absence of crucial protein (building block) required to maintain the strength and stability of the muscle. As a result, the muscle is replaced by fibrous (scar) tissue and fatty tissue. Often, the muscles-- especially the calf muscles--may appear abnormally large due this fatty replacement of the muscle ("pseudohypertrophy"), but the muscle is weak.

The muscular dystrophies may also involve the heart muscles, breathing or respiratory muscles, and--less commonly--other body systems such as brain, eye, gastrointestinal tract, and other organ systems. Scoliosis (curvature of the spine) often results as a consequence of the spinal muscle weakness and of a childís being confined to a wheelchair. Obesity is also often a problem since children are less active due to their weakness.

Who is affected by MD?
MD can affect people of all ages. Although some forms first become apparent in infancy or childhood, others may not appear until middle age or later. Duchenne muscular dystrophy is the most common childhood form, usually affecting only males, occurring in about 1 in every 3,500 live male births. Myotonic dystrophy is the most common form MD affecting adults.

What are the types of MD?
The muscular dystrophies are classified based on their clinical features, pattern of inheritance (see below), and the gene defect (when known). They include:

What are the clinical features of MD?
The clinical features of muscular dystrophy vary based on the specific form of MD.

Pain is usually not a feature of MD (except in some cases of myotonic dystrophy). Symptoms usually relate to motor difficulties and may include:

Physical signs include:

How is MD diagnosed?
After carefully evaluating a patientís medical history, the doctor will perform a thorough physical exam to rule out other causes. If MD is suspected, there is a variety of laboratory tests that can be used to confirm a diagnosis. These tests may include:

How is MD inherited?
There are three primary types of inheritance in which the faulty gene that causes MD can be passed along to offspring:

How is MD treated?
There is currently no cure for any of the muscular dystrophies, although a lot of active research is being carried out in the field. Despite this, there are treatments aimed at preventing complications due to the effects of weakness, decreased mobility, contractures, scoliosis, heart defects, and respiratory weakness. Treatments also are meant to maximize functional ability.

Education about muscular dystrophy is the most important tool with which to manage and prevent complications. The following organizations can provide more information about muscular dystrophy:

The Muscular Dystrophy Association
National Headquarters
3300 E. Sunrise Drive
Tucson, AZ 85718

Muscular Dystrophy Family Foundation
3951 N. Meridian Street, Suite 100
Indianapolis, Indiana 46208
Toll Free: (800) 544-1213

Parent Project Muscular Dystrophy
1012 North University Boulevard
Middletown OH 45042
Phone: 800-714-5437; 513-424-0696
Fax: 513-425-9907

European Neuromuscular Centre (ENMC)
Lt. Gen. van Heutszlaan 6
3743 JN Baarn
Phone: 035 54 80 481
Fax: 035 54 80 499

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This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition. For additional health information, please contact the Center for Consumer Health Information at the Cleveland Clinic (216) 444-3771 or toll-free (800) 223-2273 extension 43771. If you prefer, you may visit or This document was last reviewed on: 3/27/2008