This project has the objective of identifying genes influencing susceptibility to Tourette Syndrome (TS). We will examine patients identified in an isolated South American population (Antioquia, Colombia). The patients will be assessed in great detail so as to increase the sensitivity of the genetic analyses and to enable the study of specific clinical manifestations. Using patients from an isolated population increases the chances of detecting genetic effects and should help in identifying the specific gene mutations involved in susceptibility to TS. In addition, this research project parallels a similar study carried out by a collaborator in a closely related Hispanic population (that of the Central valley of Costa Rica). The possibility of combining the results of our investigations in these two related populations provides us with a unique opportunity to unravel the genetic basis of susceptibility to TS. Andres Ruiz-Linares M.D., Ph.D. University College London, London, United Kingdom Award: $74,500 Tourette Association of America Inc. – Research Grant Award 2004-2005