BRCA1 Cancer Gene Mutation is linked to Women Having Fewer Eggs

By Ed Uthman from Houston, TX, USA (Human Egg  Uploaded by CFCF) [CC BY 2.0 (], via W

European researchers have uncovered a link between the BRCA1 gene mutation and lowered level of a hormone that is an indicator of the number of eggs a female has remaining in her ovaries. The new study was published in Human Reproduction, one of the world’s most authoritative reproductive medical journals.

The Study

In the first large study reviewing the BRCA1 and BRCA2 genetic mutations and levels of anti-Mullerian hormone or AMH in women who carry the mutation, a group of international researchers found that carrying the BRCA1 gene mutation was associated with AMH concentrations which were on average, 25 percent lower than non-carriers. The effect was not witnessed in women who are carries of the BRCA2 mutation.

Professor Kelly-Anne Phillips, a consultant medical oncologist at Peter MacCullum Cancer Center in Victoria, Australia states, “This means that women in the mid-30s, who carry the BRCA1 mutation have, on average, ovarian reserves similar to those of non-carriers who are two years older.”

Although AMH is a reliable indicator of ovarian reserve levels, Professor Phillips said, “It’s important to remember AMH is only one indicator of a woman’s potential fertility, the ability to conceive and carry a baby to full term is affected by many other factors as well, including egg quality and whether the fallopian tubes are unobstructed, neither of which is measured by AMH. Women with low AMH levels can sometimes still have a baby and, conversely, women with high AMH levels are sometimes unable to do so.”

She further states, “However, our findings suggest that women carrying the BRCA1 mutation should try to avoid delaying pregnancy until their late 30s or 40s when fertility is reduced anyway because of their age. For women trying to conceive in their 20s, any difference in ovarian reserve between BRCA1 mutation carriers and non-carriers is unlikely to be of clinical significance.”

Women who carry both gene mutations have a much higher risk of certain cancers including; breast, ovarian, peritoneum and fallopian tubes. The risk increases as a woman becomes older and it is also higher for those with the BRCA1 mutation than it is for those with the BRCA2 mutation.

Because these cancers are harder to detect in their earlier stages, it is recommended for a woman who carries these mutations to have her ovaries and fallopian tubes removed. For this reason, many women who know they carry these gene mutations will try to have a baby when they are younger.


The research team says their findings raise the hypothesis that BRCA1 mutation carriers might have a higher than average risk of chemotherapy-induced menopause. Professor Phillips said in conclusion, “The hypothesis is that if BRCA1 mutation carriers have lower ovarian reserve than their non-carrier counterparts when they start chemotherapy for cancer treatment, the carriers may be more likely to develop menopause associated with the chemotherapy. However, this is just a hypothesis at this stage and requires further research.”


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