PCOS: polycystic ovary syndrome; FSHR: follicle-stimulating hormone receptor; ESR1: estrogen receptor 1; IVF: in vitro fertilization; rhFSH: recombinant human follicle-stimulating hormone; MII: metaphase II; MI: metaphase I; GV: germinal vesicle. Here, ESR1 is linked to polycystic ovary syndrome.