Also known as TOURETTE'S SYNDROME, this is a hereditary condition of severe and multiple TICS of motor or vocal origin. It usually starts in childhood and becomes chronic (with remissions). With a prevalence of between 0.3 and 1% of the population, a dominant GENE with variable expression may be responsible. The disorder is associated with explosive vocal tics and grunts, occasionally obscene (see COPROLALIA). The patient may also involuntarily repeat the words or imitate the actions of others (see PALILALIA). Behavioural treatments and, in certain circumstances, drugs such as HALOPERIDOL, pimozide (an oral antipsychotic drug similar to CHLORPROMAZINE hydrochloride) and clonidine may be recommended to modify this distressing, but fortunately rare, disorder.