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Insight into breast cancer risk

Researchers at the Queensland Institute of Medical Research (QIMR), as part of an international study, have identified the first region of DNA which influences the breast cancer risk associated with the BRCA1 gene.

“We have long known that mutations in BRCA1 and BRCA2 genes confer a high risk of developing breast and ovarian cancer – up to 80% for breast cancer,” said Professor Georgia Chenevix-Trench, Head of QIMR’s Cancer Genetics Laboratory.

“However, we knew something else was at play due to the variation in breast cancer risk between people who carry the BRCA1 and BRCA 2 mutations. So we went looking for other genetic variants outside the mutated genes.”

“We studied the DNA of over 8,000 women from eleven different countries who were carrying a faulty (mutated) BRCA1 gene.”

“What we found a stretch of DNA that acted like a volume control – specific changes in the gene sequence were associated with an increased breast cancer risk in women who carried a mutated BRCA1 gene. In addition, we found that the same genetic changes in women without the BRCA1 mutation influenced the risk of developing the type of breast cancer that is found in women who carry BRCA1 mutations.

“Furthermore, and quite independently, a different group of investigators found that the same genetics variants influence ovarian cancer risk in the general population. These results strengthen the evidence that breast and ovarian cancer share a similar genetic basis.”

This research is part of a larger international study to identify genetic facts that modify breast cancer risk in women carrying BRCA1 mutations.

“Our ultimate goal is to better understand the impact of the BRCA1 gene on breast cancer risk and I hope our research might one day lead to a diagnostic tool to assess breast cancer risk in the general population.”

The research was conducted in collaboration with Dr Fergus Couch at the Mayo Clinic in the USA, and Dr Antonis Antoniou from Cambridge University in the UK, as well as many other investigators from around the world.

The research has been published in Nature Genetics on 20 September 2010 and can be found at