Lack of association between TPH2 gene polymorphisms with major depressive disorder in multiethnic Malaysian population.

Introduction: Numerous association studies of candidate genes studies with major depressive disorder (MDD) have been conducted for many years; however, the evidence of association between genes and the risk of developing MDD still remains inconclusive. In this study, we aimed to investigate the association between the tryptophan hydroxylase 2 (TPH2) gene and MDD in three ethnic groups (Malay, Chinese and Indian) within the Malaysian population.

Methods: Two hundred and sixty five MDD patients who fulfilled the Diagnostic and Statistical Manual of Mental Disorders-IV criteria for MDD and 332 healthy controls were recruited for the study.