Genetic Variants Linked with Risk of Breast Cancer

Breast cancer is the second leading cause of cancer death in women. In order to better understand how breast cancer develops, researchers continue to search for genetic variants that increase risk for the disease. Two well known genes that influence the risk of breast and ovarian cancer are BRCA1 and BRCA2. Mutations in these genes account for a relatively small proportion of all cases of breast cancer, however, and researchers hypothesize that many other genetic variants may also be important. These other variants may not be as strongly linked with breast cancer risk as BRCA1 and BRCA2, but they may be more common and, in combination, may account for the majority of cases of inherited breast cancer.

Identification of genetic variants linked with breast cancer would contribute to our understanding of breast cancer biology, which in turn could lead to more effective treatments. In addition, it may eventually be possible to use information about a broad range of genetic variants in order to predict a woman’s risk of breast cancer and to individualize breast cancer prevention efforts.

Researchers involved in the current study analyzed more than 500,000 gene variants using blood samples from roughly 1,100 women with breast cancer and 1,100 women without breast cancer. The gene variants that appeared to be linked with breast cancer during this initial step were further evaluated in additional groups of women with and without breast cancer.

The end result was the identification of two previously unidentified genetic variants, 1p11.2 and 14q24.1 (RAD51L1), which significantly increased the risk the breast cancer. The first variant is located on a part of chromosome 1 that has an unknown function. The second variant is located within a gene on chromosome 14 that is involved with DNA repair.

Reference: Thomas G, Jacobs KB, Kraft P et al. A multistage genome-wide association study in breast cancer identifies two new risk alleles at 1p11.2 and 14q24.1 (RAD51L1). Nature Genetics. Online publication March 29, 2009.