A new study finds that women with BRCA1 gene mutations are more likely to be infertile as a result of an early loss of egg reserves. BRCA mutations increase the risks of breast and ovarian cancer. Infertility has been found to be associated with breast and ovarian cancer risks. The authors therefore decided to test the hypothesis that BRCA mutations may be associated with poor response to fertility treatments designed to increase egg production. In the study, ovarian stimulation was performed on 82 breast cancer patients in order to preserve fertility using embryo or oocyte cryopreservation. Of the 82 patients, 47 women had undergone BRCA testing, and 14 of these had a BRCA mutation of some type. In patients with BRCA mutations, low ovarian response rate was found to be significantly higher compared to those without BRCA mutations (33.3 versus 3.3%) and compared to untested women (2.9%). All of the women with both BRCA mutations and low response to ovarian stimulation had BRCA1 mutations. Compared with controls, women with BRCA1 mutations (but not BRCA2 mutations) produced fewer eggs (7.4 versus 12.4) and had far higher risk of low response.

The authors conclude that BRCA1 mutations are associated with lower egg reserves, a finding that may partially explain the link between infertility and breast/ovarian cancer risks. Although the study was small, the results were statistically significant. Since an estimated one in 1,000 women has a BRCA gene mutation (not all of which cause cancer), there are likely to be many women whose infertility is related to reduced egg reserves caused by a BRCA1 mutation. The rate may be higher for certain ethnic groups such as Ashkenazi Jews that have higher BRCA mutation rates. Women who have been found to have a BRCA1 mutation should take this possible early reduction in egg supply into account when planning their families.