Individuals who carry a rare genetic variant have an increased risk of developing breast cancer over their lifetimes, compared with those who do not have the variant.

Few genes have been found to have a large impact on the risk of familial breast cancer, and researchers expect that most breast cancers are influenced by the combined effects of multiple genes, each of which has a small impact on its own. One of those genes may be AKAP9.

To determine whether a rare sequence variant of the AKAP9 gene increases the risk of breast cancer, Barbara Burwinkel, Ph.D., of the German Cancer Research Center in Heidelberg and colleagues compared the frequency of the variant in 9,523 breast cancer patients with its frequency in 13,770 healthy control subjects from a large international collaboration project. Their findings were published in the Journal of the National Cancer Institute.

The team found that individuals who carry two copies of the rare variant have a 17 percent increased relative risk of developing breast cancer compared with those who carry two copies of the normal sequence. For those individuals who carry one copy of the rare variant and one copy of the normal sequence, their relative risk increased 10 percent over their lifetime.

“It is also of interest that this variant has previously been found to be associated with colorectal and lung cancer risk,” the authors write.

SOURCE:
Journal of the National Cancer Institute, March 11, 2008