Women with a gene mutation known to increase their cancer risk may have fewer eggs in their ovaries, which may have implications for family planning.
The international study led by Peter MacCallum Cancer Centre Oncologist and National Breast Cancer Foundation Fellow, Professor Kelly-Anne Phillips, checked the levels of an indicator of egg count , the anti-Müllerian hormone (AMH), in women with either the BRCA1 or BRCA2 gene mutation.
Women with these gene mutations are also at higher risk of cancers of the breast, ovaries, fallopian tubes and peritoneum.
BRCA1 mutation plays key part
Women with a BRCA2 mutation were found to have similar AMH levels to women of the same age who did not carry either mutation (non-carriers). However, women with a BRCA1 mutation had AMH concentrations that were, on average, 25% lower than women of the same age who did not carry the mutation.
“This means that women in their mid-30s who carry the BRCA1 mutation have, on average, ovarian reserves similar to those of non-carriers who are two years older,” said Professor Phillips.
Through a woman’s lifetime, AMH levels decline in line with the number of eggs remaining in her ovaries. Professor Phillips says it was important to note AMH was only one indicator of potential fertility; women with low AMH levels can sometimes still have a baby while women with high AMH levels are sometimes unable to do so.
“However, our findings suggest that women carrying the BRCA1 mutation who wish to have children should avoid, where possible, delaying pregnancy until their late 30s or 40s when fertility is reduced anyway because of their age.”
DNA repair and gene mutations
Inefficient DNA repair has been shown to contribute to the ageing of a woman’s eggs and BRCA1 and BRCA2 are both integral to mending breaks that occur in DNA.
“BRCA2 has a more limited role in double-strand DNA break repair compared with BRCA1 and BRCA2 mutation carriers tend to develop fewer cancers, and at a later age, compared with BRCA1 mutation carriers,” Professor Phillips said.
“So it is credible that any effect of mutation status on ovarian reserve would be more pronounced in BRCA1 mutation carriers. There may be a lesser effect in BRCA2 mutation carriers as well, but our study did not have adequate power to detect it.”
Findings also suggest women with BRCA1 mutations who develop cancer could be at a higher than average risk of early chemotherapy-induced menopause, though Professor Phillips said more research was needed to confirm this.
The study was published in the journal Human Reproduction and it was supported by a grant from the National Breast Cancer Foundation browse around this site.
This news article was originally posted on the Peter Mac website. Image of Professor Phillips with her patients provided courtesy of Peter Mac.
The Australian Cancer Research Foundation has supported research at Peter MacCallum Cancer Centre by providing three grants, totalling AUD $7 million, towards cutting edge cancer research equipment and technology.