Researchers identify genes linked to breast cancer
A team of international researchers has identified four new genes linked to the risk of developing breast cancer. While diagnostic testing for the disease is some way off, the findings are helping to explain why some women are more susceptible to developing the disease. The researchers also believe that the 'whole gene association' method they employed in their study can be used to unravel other cancers. Previously, scientists had only identified genes that accounted for 25% of inherited breast cancer cases (which affects hundreds of thousands of European women every year). In the 1990s, scientists located two genes, BRCA1 and BRCA2, which carried a high risk, but these were found to be rare among women. Subsequent genetic linkage studies have failed to identify further major breast cancer genes. The research, which was led by the University of Cambridge in the UK and published in Nature Genetics, confirms the idea that breast cancer susceptibility is conferred by a large number of genes, each of which has a small effect on the level of risk of developing the disease. To test this hypothesis, the researchers studied the DNA of some 50,000 women - a method called 'whole genome association'. Half of the women were victims of the disease, while the other half were healthy. The researchers found five areas of DNA that were more common in cancer sufferers. This led them to identify four genes, a variation of which, they believe, increases the risk of developing breast cancer. Two of the genes, FGFR2 and TNRC9, are believed to increase the risk of breast cancer by as much as 20% in women who have one faulty copy of a gene, and between 40% and 60% for women carrying two faulty copies in either genes. Three of the five areas identified in the study contain genes related to cell growth or cell signalling. The genes previously linked to the risk of breast cancer were involved in DNA repair and sex hormone synthesis, and metabolism pathways. The researchers believe these findings should, therefore, open up new avenues for basic research on breast cancer. 'We are very excited by these results because the regions we identified don't contain previously known inherited cancer genes,' said Professor Douglas Easton, the author of the study and director of Cancer Research UK's genetic epidemiology unit in Cambridge. 'Now we know these search methods are effective, we think that many more breast cancer genes can be found. 'These methods are already being applied by Cancer Research UK to find genes for a whole range of other cancers, including prostate, bowel and lung cancer,' he added.
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