BRD2 and amenorrhea: Elevated serum follicle-stimulating hormone (FSH) levels (>25 IU/L) on two separate occasions at least one month apart, with concomitant low estradiol (E2) levels (<50 pg/mL), and amenorrhea for at least 4 months in women younger than 40 years of age are collectively required to establish a diagnosis of POI18,20.