With this in mind, the aim of this study was to investigate if polymorphisms in the HTR2A (rs9316233), HTR3A (rs1062613), HTR3B (rs1176744), SERT (5-HTTLPR) and COMT (rs4680) genes contribute to pain perception in TMD myalgia and if pain and psychosocial factors such as stress, anxiety and depression correlate. Here, SLC6A4 is linked to major depressive disorder.