background Family studies on Tourette syndrome and obsessive-compulsive disorder reveal that the symptoms of the two disorders overlap. The nature of the association is complex, and the question of whether the two disorders are different expressions of the same disease or are in fact two distinct disorders has not yet been fully resolved.
method This review addresses the nature of the relationship between Tourette syndrome and obsessive-compulsive disorder. For this purpose Medline was searched for relevant literature published between 1985 and the present. Both phenomenological and genetic aspects of the disorders are compared.
results Data on the genomics of Tourette syndrome and obsessive-compulsive disorder are still incomplete and much research remains to be done. However, the available data seem to support the hypothesis that the subtle differences between Tourette syndrome and tic-related obsessive-compulsive disorder on the one hand and tic-free obsessive-compulsive disorder on the other hand have a genetic basis.
conclusion In the diagnosis and treatment of such disorders it is important to distinguish between tic-free and tic-related forms and to regard them as clinically relevant subtypes.