Candidate genes were selected from two different points of view: Genes already associated with PCOS and its clinical features (CEBPB, EPHX1, EPM2A, FST, IGFBP1, INSR, LHCGR, PPARG1A) and genes involved in the stress response system (SLC6A4, COMT, MAOA, BDNF, NR3C1, FKBP51, TBKBP1) and neurotransmitter signaling (HTR1A, TPH2). The gene discussed is TPH2; the disease is polycystic ovary syndrome.