Studies were selected with the following inclusion/exclusion criteria: Women affected by PCOS, intervention with MI with or without DCI, assessment of insulin levels, insulin sensitivity, HOMA index, BMI, levels of tryglicerides, hormone levels (testosterone, estradiol, androstenedione, sex hormone-binding globulin plasma, DHEAS, AMH, LH, and FSH), menstrual frequency, oocyte quality; english language. The gene discussed is SULT2A1; the disease is polycystic ovary syndrome.