HIGH-THROUGHPUT FLUORESCENCE-BASED CONFORMATION-SENSITIVE GEL-ELECTROPHORESIS (F-CSGE) IDENTIFIES 6 UNIQUE BRCA2 MUTATIONS AND AN OVERALL LOW INCIDENCE OF BRCA2 MUTATIONS IN HIGH-RISK BRCA1-NEGATIVE BREAST-CANCER FAMILIES

Mutational analysis of cancer susceptibility genes has opened up a new era in clinical genetics. In this report we present the results of mu tational analysis of the BRCA2 coding sequences in 105 high-risk indiv iduals affected with breast cancer and/or ovarian cancer and previousl y found to be negative for mutations of the BRCA1 coding sequence in o ur laboratory. These individuals have a positive family history with t hree or more cases of breast cancer and/or ovarian cancer at any age f rom the same side of the family tree. In order to perform a high throu ghput and reliable mutational analysis of the BRCA genes, we have adap ted the conformation-sensitive gel electrophoresis mutation-scanning a ssay to a fluorescent platform. The advantages are speed, reproducibil ity and enhanced resolving power of the scanning method. Four unique m utations, including one missense and three frameshift mutations, were identified in the pool of 60 non-Jewish patients (7%). Two cases of th e 6174delT mutation were identified in the 45 Ashkenazi Jewish individ uals studied (5%). In addition, two novel frameshift mutations, not ch aracteristic of the Jewish subgroup, were identified. Thus there were four mutations in total in this ethnic subgroup (9%). The six mutation s identified in this combined patient pool, excluding the 6174delT mut ations, are novel and have not been previously reported in the Breast Cancer Information Core (BIC) database. The results indicate that BRCA 2 mutations account for the disease in less than 10% of this patient p opulation. In addition, there is no significant difference in frequenc y of BRCA2 mutations between the Ashkenazi Jewish and non-Jewish famil ies in our clinical patient pool.