In recent years, breast cancer research has focused large ATM Gene Found to Have Role in Frequent Breast Cancer Cases Among Family Members (dateline May 21, 2002) | Breast Health News | Imaginis - The Women's Health & Wellness Resource Network

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ATM Gene Found to Have Role in Frequent Breast Cancer Cases Among Family Members (dateline May 21, 2002)

In recent years, breast cancer research has focused largely on genetic causes for the disease. In 1994, researchers discovered that changes to two genes, BRCA1 (breast cancer gene 1) and/or BRCA2 (breast cancer gene 2), increase a woman's risk of developing breast cancer. Now, a new study sheds light on another gene that may affect breast cancer risk: the ATM gene (ataxia telangiectasia). Australian researchers have found that two specific types of mutations in the ATM gene significantly increase the risk for breast cancer and help explain the frequency of breast cancer diagnoses in some families. Though more research on the ATM gene is needed, if further studies confirm its connection to breast cancer, physicians may be able to begin testing for ATM gene mutations, similar to the way they now test for BRCA gene mutations in some women at high risk for breast cancer.

When functioning normally, ATM helps control cell division. However, inherited mutations of the ATM gene from both the father and the mother have been associated with a loss of brain cells that causes a lack of muscle control and increased cancer rates. Inheriting one mutation of the ATM gene has also been shown to increase the risk for breast cancer in previous research, although the risk was thought to be very small and therefore not associated with a high frequency of breast cancer in some families.

In a new study published in the Journal of the National Cancer Institute, lead researcher Georgia Chenevix-Trench, PhD, of the Queensland Institute of Medical Research in Australia, and her colleagues searched for two types of ATM gene mutations in 76 families with a high incidence of breast cancer. Though the overall number of families with the ATM gene mutations was small, the researchers estimated that those with the ATM mutations were at nearly 16-times higher risk of developing breast cancer, compared to women without the genetic mutations. Among three families found to have the mutations in the study, 60% of the women in those families had developed breast cancer.

Previous research has linked the ATM gene with the BRCA1 gene, another gene associated with a higher risk of breast cancer when mutated. In a 1999 study published in the journal Science, Dr. Stephen Elledge and his colleagues at the Baylor College of Medicine in Houston, Texas and the Howard Hughes Medical Institute explained that BRCA1 might rely on ATM to repair some types of cell damage. When DNA damage occurs in cells, BRCA1 helps the body repair those cells--a process that may prevent tumor development. However, BRCA1 cannot begin the process of repairing cells when the damage is caused by some types of radiation exposure. In these cases, BRCA1 must rely on ATM to initiate the repairs.

According to Dr. Elledge, the ATM gene may become mutated during a person's life, perhaps from exposure to radiation or certain chemicals. Sunlight and even a poor diet may contribute to ATM gene mutations, suggested Dr. Elledge. People may also be born with a mutated form of the ATM gene.

While further research is needed to better understand the connection between ATM gene mutations and breast cancer, experts believe this is an important area of research. BRCA gene mutations are thought to account for approximately 10% of breast cancer cases. It may be that ATM gene mutations also contribute significantly to genetic breast cancer cases.

If further research confirms that ATM gene mutations increases breast cancer risk, physicians may begin testing for the gene mutations in some women at high risk for breast cancer, especially if the disease is common among family members. Currently, BRCA genetic testing is available to select women to determine whether they carry mutations of the BRCA1 or BRCA2 genes, which put them at significantly higher risk of breast cancer and ovarian cancer, compared to the general population. (Eligible candidates for BRCA gene testing include those with a strong family history of breast or ovarian cancer, those with an early onset of breast cancer in family members, and those of Eastern and Central European/Ashkenazi Jewish ancestry with a family history of breast and/or ovarian cancer).

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