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). This evidence concerns the gene EPHX1 and polycystic ovary syndrome.