[Tic disease. Current genetic and neurochemical factors]

We review historical, conceptual, clinical and diagnostic criteria as well as present genetic and neurochemical factors of tic disorders. Epidemiologic data suggest that tic is an organic disease with autosomal dominant transmission. We emphasize immunohistochemical studies particularly related to the dopaminergic, noradrenergic and serotonergic systems. These modulate the activity of the cortico-striato-thalamocortical circuits implicated in both Tourette's syndrome and obsessive-compulsive disorder.