CYP19A1 and polycystic ovary syndrome: One of the intraovarian steroidogenesis abnormalities that are hypothesised to lead to ovarian failure in PCOS is a decrease in activity of aromatase enzyme, causing an imbalance of hormones, hyperandrogenism, and excess androgens within the ovaries leading to polycystic ovaries could be anticipated from decreased activity of the enzyme aromatase, which determines production rate of production of estrogen from androgen (3, 5).