ESR1 and polycystic ovary syndrome: The mechanism for this is unknown; however, the researchers believe the outcome could be possibly by reversal of anomalies in the hypothalamic–pituitary–adrenal axis or by elevation in the brain-derived neurotrophic factor concentration [27] Aberrant expression of Estrogen receptors alpha (ERα) and beta (ERβ) causes folliculogenesis and ovulatory dysfunction in PCOS patients [28].