Common gene variant boosts breast cancer risk

Washington, Mar 15 : An international research consortium, led by scientists at the German Cancer Research Center (Deutsches Krebsforschungszentrum, DKFZ), has identified a common gene variant that increases the risk of developing breast cancer.

A family history of breast cancer is reported in almost 5-10 pct breast cancer cases, suggesting the role of hereditary and genetic factors in the development of the disease.

The study on 9,523 breast cancer patients including 2,795 familial breast cancer cases and almost 14,000 healthy women, found that alterations in the genes known as BRCAI and BRCAII are a major cause of familial breast cancer and are responsible for almost 25 percent of such cases.

"In Germany, 75 percent of familial breast cancers are not attributable to mutations in BRCAI and BRCAII. We assume that these cancers are caused in part by rare mutations and in part by unfavorable combinations of risk variants in various genes, which, on their own, have only little effect. Only very few of these have been identified so far - we are searching for the other ones," said Dr. Barbara Burwinkel, lead author and Associate Professor at the DKFZ.

It is known that members of the AKAP protein family cause the transmission of important signals in a cell. This led the scientists to suspect that these proteins can be involved in cancer development. And according to the study this also holds true for breast cancer.

In the study, six gene variants in the AKAP family were studied and it was found that 2 of these variants, both located on the AKAP9 gene, are linked to an increased breast cancer risk.

As the two gene variants are always inherited together, further research will be needed to know if one of these or both variants in combination are responsible for the risk effect.

The scientists discovered that women carrying the two variants in both copies of their AKAP9 genes, had a 17 pct increased risk of developing breast cancer in the course of their lifetimes.

On the other hand, the effect is even more significant in women from breast cancer families: their risk is increased by 27 pct. In case only one of the AKAP9 copies is affected, the breast cancer risk is only slightly elevated by approximately 8 pct or 12 pct for women from breast cancer families, respectively.

"This shows that the AKAP9 variants have much less effect on breast cancer risk than, for example, BRCA mutations. On the other hand, these variants are much more common in the population. We also do not know yet which control cycles of the cell metabolism are affected and how this can lead to cancer. But there is already evidence suggesting that the two variants also increase the risk of developing lung cancer or colon cancer," said Dr. Burwinkel.

ANI