GNRH1 and hypoalphalipoproteinemia, primary, 1: Functional hypothalamic amenorrhea (FHA) is a reversible endocrine disorder characterized by a disturbance of the pulsatile secretion in the hypothalamus of the gonadotropin-releasing hormone (GnRH), which results in the impaired function of the hypothalamic–pituitary–ovarian axis, chronic anovulation and hypoestrogenism [1].