Approximately 5 to 10 percent of all cases of breast cancer are hereditary and associated with inherited gene mutations. Hereditary breast cancers tend to develop early in a woman’s life and are more likely to affect both breasts. Researchers have identified a correlation between variations in specific genes and the increased risk for developing breast cancer.
BRAC1 and BRAC2
Everyone has the BRAC1 (Breast Cancer Gene 1) and BRAC2 (Breast Cancer Gene2). These two genes function to repair cell damage and maintain the normal growth of breast cells. Women with certain mutations of these genes as well as men with BRAC1 mutations have an increased risk for developing breast cancer. Researchers are learning that additional mutations in areas of chromosomes called SNPs (single nucleotide polymorphisms) may predispose women with and without BRAC1 mutations to developing breast cancer.
Other gene mutations, though rare and of lesser risk than BRAC1 and BRAC2 variations, have been identified. The CDHI gene makes a protein that helps cells bind together to form tissue. Research has shown that women with a CDHI mutation have an increased risk for developing invasive lobular breast cancer. Invasive lobular breast cancer begins in the milk producing glands or lobules of the breast. The cancerous cells then spread to other parts of the body.
The CHEK2 gene produces a protein which stops tumor growth. A prospective study of 9,231 Danish women revealed that a mutation of the CHEK2 gene is associated with a three-fold risk of breast cancer in women in the general population. Leader researcher, M. Weischer, and colleagues reviewed the 34 year observation records of the initial test group and conducted a case-controlled study of 5,766 participants.
The PTEN gene produces a protein, which regulates cell growth and acts as a tumor suppressor. Mutations in the PTEN gene increase the risk for developing breast cancer as part of a rare hereditary cancer syndrome called Cowden syndrome.
The ATM gene produces a protein, which controls the rate at which cells grow and divide.