Women living with the gene mutation that increases their risk of ovarian and breast cancer may also have fewer ovarian eggs and struggle to get pregnant if they leave it too late, new Australian-led research shows.
The international study, published in the leading scientific journal Human Reproduction today, investigates the fertility of women with a BRCA1 or BRCA2 mutation – a genetic abnormality, which heightens their risk of developing cancers of the breast, ovaries, fallopian tubes and peritoneum.
The research found that women with a BRCA1 mutation had 25 per cent less of the anti-Müllerian hormone (AMH), key indicator of egg count, than women of the same age who did not carry the mutation.
Study lead and Peter MacCallum Cancer Centre oncologist, Professor Kelly-Anne Phillips, says the reduction is equivalent to the women having two years' less supply of ovarian eggs.
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.
“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,” says Professor Phillips.
However, the study found that women with a BRCA2 mutation had similar AMH levels to women of the same age without the genetic abnormality. Professor Phillips explains that BRCA1 is more 'potent' than BRCA2 in potentially causing fertility issues for women with the gene mutation.
BRCA mutations are rare in the general population – about 0.1 per cent of the Australian population (or 2.4 million) will have the BRCA1 mutation and around 0.2 per cent (4.8 million) have the BRCA2 mutation.
“This estimate is across our whole population but we know that BRCA1 mutations are more common in some ethnic groups like Ashkenazi Jews,” states Prof Phillips.
“For Australian people who are of Ashkenazi Jewish descent, the prevalence will be something more like one in 100. And across the world, in places like Israel, prevalence is even higher so this research would be very important.”
Australian-born identical twins, Maria Fay and Joanne Weedon both have the BRCA1 gene mutation. At age 38, they each have two children.
Although Ms Weedon has never had any problems getting pregnant, Ms Fay explains that she’s always experienced fertility issues.
“I’ve had several miscarriages and really struggled to get pregnant on every occasion,” says Ms Fay. “At the time, I was diagnosed with unexplained infertility but now looking at the results of this research, it’s put why I’ve had fertility issues all into perspective.”
The differences between women with the BRCA1 and women without genetic abnormalities are subtle in youth but increase as women enter their late 30s and early 40s.
The study shows the differences between women with the BRCA1 and women without genetic abnormalities are subtle in youth but increase as women enter their late 30s and early 40s.
“The findings may be more important for older women with the genetic mutation trying to get pregnant,” says Professor Phillips, the National Breast Cancer Foundation Fellow.
“They should try not to delay childbearing until late 30s and early 40s if they can.”
“For older women: the more information you have regarding BRCA1 or 2, it will be to your advantage.”
Professor Phillips explains that women with the BRCA1 mutation, who also face a heightened risk of ovarian cancer around their 40s, may decide to have their ovaries and fallopian tubes removed.
Hollywood star and human rights activist, Angelina Jolie grabbed the world’s attention in 2013, reporting she undergone a preventative double mastectomy because she had the BRCA1 mutation.
“If you are going to have that procedure done, you have to have babies before you reach 40,” says Professor Phillips. “This is another reason for those women with the BRCA1 gene mutation to think about not delaying childbearing.”
Ms Fay has had her ovaries surgically removed, while Ms Weedon has had her fallopian tubes surgically taken away and made plans to remove her ovaries.
“If women are in their 20s, they know they have BRCA1 and have a choice to get pregnant, do it and don’t put it off,” recommends Ms Weedon.
Inefficient DNA repair has been shown to contribute to the ageing of a woman’s eggs. BRCA1 and BRCA2 are both essential to mending breaks that occur in DNA.