It has been suggested that women who carry a mutation in the ATM gene have an estimated 20-60% increased risk for breast cancer (Renwick et al Nature Genetics. 2006; 38(8):873-875). Those with an ATM gene mutation are thought to be at increased risk for early-onset breast cancer and bilateral breast cancer. However, the exact breast cancer risk, and whether or not there is any other cancer risk, conferred by a carrying a mutation in the ATM has not been determined. Some studies have also suggested a possible increased risk of sensitivity to radiation (Broeks et al Breast Cancer Res Treat. 2008; 107:243–248). Research in this area is ongoing and our understanding of the implications of carrying a single ATM mutation may change in the future. It is important for patients to keep in contact with their doctors and genetics providers for updates in this area.
The ATM gene is typically associated with an autosomal recessive condition called ataxia-telangiectasia (AT). AT is characterized lack of muscle coordination (cerebellar ataxia ) at an early age, dilated blood vessels (telangiectases ) in the whites of the eyes, immune defects, and a predisposition to certain cancers, particularly leukemia and lymphoma. For an individual to have AT, he/she would have inherited a changed, or mutated, copy of the ATM gene from both parents. This means that each parent of a child with AT is a carrier of an ATM mutation. It is important to note that carriers are not at an increased risk for developing the neurologic features of AT but do have an increased risk for breast cancer.
Cancer Screening Recommendations
Breast Cancer Screening: Annual mammogram and consider breast MRI with contrast starting at age 40.
Breast Cancer Risk Management: Consider risk reducing mastectomies based on family history.
Comments: Insufficient evidence to recommend against radiation therapy. The 7271T>G missense mutation may act in a dominant-negative fashion resulting in a lifetime cancer risk as high as 60% by age 80 (which is higher than truncating mutations, where risks are in the range of 30-40%). Counsel for risk of autosomal recessive condition in offspring.
Recommendations based on National Comprehensive Cancer Network Guidelines Version 1.2017 Genetic/Familial High Risk Assessment: Breast and Ovarian Cancer