TPH2 and psychiatric disorder: Genes coding for: interleukin 1, alpha (IL1A), interleukin 1, beta (IL1B), tumor necrosis factor (TNF), serotonin receptor 2A (HTR2A), the promoter of the serotonin transporter gene (5-HTTLPR) and tryptophan hydroxylase 2 (TPH2) are candidate genes whose deregulation is thought to be central to psychiatric disorders [1].