To test this hypothesis, we measured expression of Notch2 and Hes-related family bHLH transcription factor with YRPW motif 2 (Hey2) and Hes family bHLH transcription factor 1 (Hes1) in granulosa cells of antral follicles of PCOS patients and mice with dehydroepiandrosterone (DHEA)-induced PCOS. This evidence concerns the gene HEY2 and polycystic ovary syndrome.