The PCOS patients and control people were genotyped for ESR1 rs2234693 in six studies (16, 17, 19, 20, 22, 23), for ESR1 rs9340799 in five studies (16, 19, 20, 22, 23), and for ESR2 rs4986938 in six studies (16–19, 21, 22). This evidence concerns the gene ESR2 and polycystic ovary syndrome.