Women who carry the faulty versions of genes called BRCA1 and BRCA2 are also at an increased risk of developing breast, ovarian and fallopian tube cancers, the team said, suggesting that women carrying BRCA1 mutation should not delay pregnancy till their late 30s or 40s as fertility may be reduced because of their age.
“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 lead researcher Kelly-Anne Phillips, professor and oncologist at the Peter MacCallum Cancer Centre in Melbourne, Australia.
The study analysed the levels of anti-Mullerian hormone (AMH), an indicator of egg counts, in women with either the BRCA1 or BRCA2 mutation.
The team found that women with BRCA1 mutations had 25 percent lower AMH concentrations than non-carriers on average, which is equivalent of a two-year age increase for a non-carrier woman in her 30s.
Also, BRCA1 mutation was found to damage DNA. The team said the BRCA1 mutation might stop DNA being properly repaired, which increases the risk of both cancer and infertility.
The findings also raise the hypothesis that BRCA1 mutations carriers may have a higher than average risk of chemotherapy-induced menopause.
For the results, the team analysed 693 women aged 25 to 45 who had no personal history of cancer.
A total of 172 women were carriers and 216 women non-carriers from families carrying the BRCA1 mutations, and 147 carriers and 158 non-carriers were from families with the BRCA2 mutations.