Molecular NeuroscienceTryptophan hydroxylase gene polymorphism (A218C) and suicidal behaviorsTsai, Shih-Jen1,2,4; Hong, Chen-Jee1,2; Wang, Ying-Chieh3 Author Information 1Department of Psychiatry, Veterans General Hospital, No. 201, Shih-Pai Road, Sec. 2, Taipei 11217 2School of Medicine, National Yang-Ming University, Taipei 3Section of Psychiatry, Yu-Li Veterans Hospital, Yu-Li, Taiwan, ROC 4Corresponding Author and Address: Shih-Jen Tsai, Department of Psychiatry, Veterans General Hospital, No. 201, Shih-Pai Road, Sec. 2, Taipei 11217 Received 21 September 1999; accepted 30 September 1999 NeuroReport: December 16, 1999 - Volume 10 - Issue 18 - p 3773-3775 Buy Abstract SEROTONERGIC dysfunction is implicated in mood disorders and suicidal behaviors. Genetic variants of tryptophan hydroxylase (TPH), a rate-limiting enzyme in the biosynthesis of serotonin, were associated with suicidal behaviors in three reports, but were not found in other studies. We investigated the TPH A218C polymorphism in 151 subjects with mood disorders and 200 control subjects. The results demonstrated a significant difference in genotypic distribution between controls and depressed patients, but not bipolar patients. A positive association between TPH polymorphism and suicidal behaviors was found in depressed patients and not in bipolar patients. We suggest that the association of TPH variants and suicide might depend on the diagnosis, and TPH mutation plays no major role in the pathogenesis of bipolar disorders. © 1999 Lippincott Williams & Wilkins, Inc.