Definition of Gilles de la Tourette syndrome:

Gilles de la Tourette syndrome is a disorder of the nervous system that causes a person to make repeated and uncontrolled (involuntary) movements and sounds (vocalizations) called tics. The disorder is commonly called Tourette syndrome.

See also:

• Chronic motor tic disorder
• Facial tics
• Transient tic disorder

Causes, incidence, and risk factors:

Tourette syndrome is named for Georges Gilles de la Tourette, who first described this disorder in 1885. There is strong evidence that Tourette syndrome is passed down through families, although the gene has not yet been found.

The syndrome may be linked to problems in certain areas of the brain, and the chemical substances (dopamine, serotonin, and norepinephrine) that help nerve cells talk to one another.

Tourette syndrome can be either severe or mild. About 10% of Americans have a mild tic disorder, but far fewer have more severe forms of Tourette syndrome. Many people with very mild tics may not be aware of them and never seek medical help.

Tourette syndrome is four times as likely to occur in boys as in girls.