Which receptor and enzyme defects cause amenorrhea?

Updated: Jan 08, 2019
  • Author: Kristi A Tough DeSapri, MD; Chief Editor: Richard Scott Lucidi, MD, FACOG  more...
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Answer

Congenital adrenal hyperplasia as a result of 17 alpha-hydroxylase deficiency (CYP17) causes an excess of deoxycortisone to be produced and deficiency of cortisol and adrenal and gonadal sex steroids. Patients with this disorder who experience primary amenorrhea can be either genotypic males (XY) or females (XX). [3]

Complete androgen insensitivity syndrome is caused by a defective androgen receptor. Although patients with this syndrome have a 46,XY karyotype and produce testicularly derived testosterone, the testosterone cannot activate cellular transcription; therefore, the patient has female external genitalia. In most cases the disorder is X-linked. The testes, located internally and sometimes in the labia or inguinal area, also produce müllerian-inhibiting hormone, so all müllerian-derived structures (ie, the fallopian tubes, uterus, upper third of the vagina) are absent. [16, 17]

Gonadotropin resistance is rare, but inactivating mutations of the receptors for LH and FSH can cause anovulatory amenorrhea. [18]

Aromatase deficiency is also a rare disorder. Aromatase catalyzes the conversion of androgen to estrogen. When estrogen synthesis cannot occur, increased levels of testosterone result and virilization of the female occurs. Often, girls have cystic ovaries and resultant amenorrhea. [19]


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