Untying the gordian knot: the genetics of Tourette syndrome. A review of the current status of the genetics of Tourette syndrome is presented. Over the course of the 104 years since Gilles de la Tourette described the syndrome that bears his name, a body of carefully collected, described, and analyzed data has produced a model of the genetics that implicates a single dominant gene that is variably penetrant in males and females. Moreover, the locus of action of this gene is most likely in the dopaminergic system of the midbrain. A systematic search for this gene using recombinant DNA techniques is under way. 