Role of the ATM Gene in Bilateral Breast Cancer Following Radiotherapy

The purpose of this project is to determine whether women who developed bilateral breast cancer following radiotherapy for an initial breast cancer had a higher incidence of heterozygosity for a mutation in the ATM gene than either breast cancer patients who did not develop a second breast cancer or bilateral breast cancer patients who did not receive radiotherapy. To accomplish this, during the first three years of this project, DNA samples were isolated from unilateral and bilateral breast cancer patients and screened for ATM mutations using a Non-radioisotopic RNase Cleavage-based Assay NIRCA. However, not a single mutation was discovered from any of these patients which raised a concern as to the sensitivity of this assay. To address this concern, the PI of this project recently purchased an instrument for the performance of denaturing high performance liquid chromatography DHPLC. This is a high throughput technique in which large numbers of DNA samples can be rapidly screened with a high degree of sensitivity and accuracy. During the fourth year of this study, representing a no-cost extension of this project, all of the DNA samples obtained from the unilateral and bilateral breast cancer patients will be re-screened for ATM mutations using DHPLC. We have begun this process with screening eight ATM exons and have already found eight patients possessing base sequence alterations that had previously gone undetected using NIRCA.