The BRCA1 and BRCA2 genes protect against breast and ovarian cancer, and a mutation in either gene increases the risk of cancer. It is estimated that 1 in 350 women has a mutation in BRCA1 or BRCA2.
BRCA1 and BRCA2 are genes that are normally present in breast and other tissue cells, and both produce proteins to help repair damaged DNA, or destroy the cell itself if the DNA is beyond repair.
Angelina Jolie famously underwent a preventive mastectomy in 2013 after discovering that she inherited the BRCA1 mutation, which gave the mutation its name, the “Jolie gene.”
The Monash University study, published in the journal EBioMedicine, found that lacking the BRCA1 gene in mice reduces litter size (the offspring produced in a single birth) and the quality of their eggs, especially as they age.
Egg maturation rates were reduced by 45% in reproductive-age mice lacking BRCA1.
The study analyzed blood hormone levels and estimated the number of eggs in ovarian tissue in women with BRCA mutations.
Lead author Professor Carla Hutt, head of the Hutt Laboratory at the Monash Biomedicine Discovery Institute, said previous clinical models had suggested that partial loss of BRCA1 function could reduce the number of eggs in the ovary.
“The potential effects of complete loss of BRCA1 function on egg count and fertility have not been studied before,” she added. “Using a unique mouse model with targeted loss of BRCA1 specifically in eggs, this study comprehensively assessed fertility across the entire reproductive lifespan. The data show that BRCA1 is important for maintaining egg count, egg quality, and fertility.”
And it was done Mice were created without the BRCA1 gene in their eggs, resulting in a mutation that causes complete loss of BRCA1 function. While their fertility lifespan was unchanged, the mutation resulted in reduced abdominal sizes and egg numbers. Egg maturation was also impaired compared to mice without the mutation.
In women, measuring levels of anti-Müllerian hormone (AMH) in the blood is a standard indirect indicator of how many eggs they may have. However, researchers found no association between AMH levels and the number of eggs estimated from ovarian tissue in a small group of premenopausal women with BRCA mutations. This suggests that more studies are needed to better understand whether the hormone is a good indicator of egg count in women with BRCA mutations.
The study expands knowledge of the critical role of BRCA1 in maintaining fertility, said Dr. Amy Winship, co-senior author of the study, from the Hatt Lab.
Future studies are needed to understand the effects of cancer treatments on fertility in the context of BRCA mutations, said study co-author Dr. Lauren Alessi, of the Hatt lab.
Source: Medical Express
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2024-08-01 23:18:57
