Thus, E2 measurements are useful in assisted reproduction to monitor follicular development and in the clinical evaluation of hypogonadism, hirsutism, polycystic ovary syndrome, amenorrhea, female infertility, menopause, gonadal tumors, and feminization in males or monitoring of aromatase inhibitor therapy in breast cancer, among others [1]. Here, CYP19A1 is linked to breast carcinoma.