The pathogenic mechanisms of POI are highly heterogeneous and can be divided into four major categories: follicular migration defect early in embryogenesis; an early decrease in the primordial follicles; increased follicular death; and altered maturation or recruitment of primordial follicles. Genetic causes such as Turner syndrome have initial ovarian development but then ovaries degenerate rapidly during prenatal life, often leading to gonadal dysgenesis with streak ovaries. In those cases where POI is associated with adrenal autoimmunity, histological examination almost always confirms the presence of an autoimmune oophoritis in which follicles are infiltrated by lymphocytes, plasma cells, and macrophages that attack mainly steroid-producing cells and eventually result in follicular depletion. (Since the serum
Anti-Müllerian hormone (AMH) level is correlated with the number of remaining primordial follicles some researchers believe the above two phenotypes can be distinguished by measuring serum AMH levels. Genetic associations include genetic disorders,
DNA repair deficiency BRCA1 protein plays an essential role in the repair of DNA double-strand breaks by
homologous recombination. Women with a
germline BRCA1 mutation tend to have premature menopause as evidenced by the final amenorrhea appearing at a younger age. BRCA1 mutations are associated with occult POI. Impairment of the repair of DNA double-strand breaks due to a BRCA1 defect leads to premature ovarian aging in both mice and humans. In addition to BRCA1, the
MCM8-MCM9 protein complex also plays a crucial role in the recombinational repair of DNA double-strand breaks. In humans, an MCM8 mutation can give rise to premature ovarian failure, as well as
chromosomal instability. MCM9, as well as MCM8, mutations are also associated with ovarian failure and
chromosomal instability. The MCM8-MCM9 complex is likely required for the
homologous recombinational repair of DNA double-strand breaks that are present during the pachytene stage of
meiosis I. In women
homozygous for MCM8 or MCM9 mutations, failure to repair breaks apparently leads to
oocyte death and small or absent
ovaries. ==Diagnosis==