Muscular Dystrophy

About MD

Muscular dystrophy (MD) is a genetic disorder that gradually weakens the body's muscles. It's caused by incorrect or missing genetic information that prevents the body from making the proteins needed to build and maintain healthy muscles.

A child who is diagnosed with MD gradually loses the ability to do things like walk, sit upright, breathe easily, and move the arms and hands. This increasing weakness can lead to other health problems.

There are several major forms of muscular dystrophy, which can affect the muscles to varying degrees. In some cases, MD starts causing muscle problems in infancy; in others, symptoms don't appear until adulthood.

There is no cure for MD, but researchers are quickly learning more about how to prevent and treat it. Doctors are also working on improving muscle and joint function and slowing muscle deterioration so that those with MD can live as actively and independently as possible.

First Symptoms

Many kids with muscular dystrophy follow a normal pattern of development during their first few years of life. But in time common symptoms begin to appear. A child who has MD may start to stumble, waddle, have difficulty going up stairs, and toe walk (walk on the toes without the heels hitting the floor). A child may start to struggle to get up from a sitting position or have a hard time pushing things, like a wagon or a tricycle.

Kids with MD often develop enlarged calf muscles (called calf pseudohypertrophy) as muscle tissue is destroyed and replaced by fat.

Diagnosis

When first suspecting that a child has muscular dystrophy, a doctor will do a physical exam, take a family history, and ask about any problems — particularly those affecting the muscles — that the child might be having.

In addition, the doctor may perform tests to determine what type of MD is involved and to rule out other diseases that could cause the problem. These might include a blood test to measure levels of serum creatine kinase, an enzyme that's released into the bloodstream when muscle fibers are deteriorating. Elevated levels indicate that something is causing muscle damage.

The doctor also may do a blood test to check the DNA for gene abnormalities or a muscle biopsy to examine a muscle tissue sample for patterns of deterioration and abnormal levels of dystrophin, a protein that helps muscle cells keep their shape and length. Without dystrophin, the muscles break down.

Types of Muscular Dystrophy

The different types of muscular dystrophy affect different sets of muscles and result in different degrees of muscle weakness.

Duchenne muscular dystrophy is the most common and the most severe form of MD. It affects about 1 out of every 3,500 boys. (Girls can carry the gene that causes the disease, but they usually have no symptoms.) This form occurs because of a problem with the gene that makes dystrophin. Without this protein, the muscles break down and a child becomes weaker.

In cases of Duchenne muscular dystrophy, symptoms usually begin to appear around age 5, as the pelvic muscles begin to weaken. Most kids with this form need to use a wheelchair by age 12. Over time, their muscles weaken in the shoulders, back, arms, and legs.