Positive Association between Tourette’s Disorder and Catechol-O-Methyl Transferase Gene in Korean Subjects

This study was conducted to investigate the association of the Catechol-O-Methyl Transferase (COMT) polymorphism with Tourette’s disorder (TD) in a Korean sample of families with TD probands. The relationship between the risk alleles and specific clinical features (tic severity, comorbidity, drug response) was also explored. Patients were recruited from the Tic Disorder clinic at the Child & Adolescent Psychiatric Division of Seoul National University Hospital and assessed through a 2 stage evaluation. Firstly, all of the patients and parents underwent a semistructured interview using the Korean version of the Kiddie-Schedule for Affeetive Disorders and Schizophrenia for School Age children, Present and Life time Version (K-SADSPL). Secondly, all of the patients underwent a clinical interview and tic severity assessment with the Korean version of the Yale Global Tic Severity Scale (YGTSS). The subjects in the control group were recruited from the health promotion center of our hospital and were evaluated by means of the Symptom Checklist 90 (SCL-90) and Structured Clinical Interview for DSM-IV (SCID-IV). Through this process, a total of 42 children and adolescents with TD, their 84 parents and 86 control subjects were finally recruited. Genotyping for the Val158Met polymorphism of the COMT gene was done by a standardized method. After the collection of the genetic data of all of the patients, parents and control subjects, a casecontrol comparison and transmission dysequilibrium test were performed using SPSS version 11. Based on the case-control comparison, the frequencies of the Lallele and LL genotype were significantly higher in the TD group. However, no differences were found in the transmission disequilibrium test (TDT). No significant differences were found in the family history of tic, Attention Deficit Hyperactivity Disorder (ADHD), Obsessive-Compulsive Disorder (OCD), drug response or comorbid conditions among the TD patients with the three different genotypes. Although the results of this study should be interpreted cautiously, due to the small sample size and negative finding in the TDT test, this is the first report of a positive association between the functional polymorphism of the COMT gene and TD.