There is strong evidence that Tourette Syndrome (TS) is inherited, and yet symptoms, even within families, vary widely. This may mean that that several genes or environmental factors combine to play a role in producing the symptoms of TS. To understand how genes affect TS, rather than looking for mutations in single genes (DNA), we have used “gene arrays,” which are postage stamp sized chips that measure the level of expression (amount of RNA) from thousands of genes simultaneously. This may enable us to understand complex gene-gene and gene-environment interactions that occur in neurological diseases. Although TS symptoms originate in the brain, this tissue is not readily available for research purposes, and consequently we began to use gene-array technology to identify differences in blood RNA levels in several neurological diseases, including TS. Results have been promising. The primary aim of this study is to determine whether altered gene expression (RNA levels) in blood from children and adolescents with TS occurs. If we learn that specific genes are consistently overactive or under-active in TS, we may gain important knowledge about how certain gene-gene or gene-environment interactions produce or worsen TS symptoms. Ultimately, this may allow us to better understand why patients with TS have a broad range of symptoms, different symptom triggers, different medication treatment responses, and different co-morbid conditions (ADHD, OCD). Donald L. Gilbert, M.D., M.S. Cincinnati Childrens Hospital, Cincinnati, OH Award: $73,819 Tourette Association of America Inc. – Research Grant Award 2004-2005