Detection of BRCA1 gene mutations in families with breast cancer patients and their healthy relatives.

Eighty-three families with two or more cases of breast and ovarian cancer were selected to evaluate the prevalence rate of BRCA1 gene mutations, and identify healthy carriers. Blood samples from patients and healthy relatives were obtained. Haplotype study of the 17q21 region using 7 polymorphic markers was performed. Mutational analysis of the coding exons of the BRCA1 gene was performed by the PCR-SSCP method and direct sequencing. We detected germline mutations (frameshift and missense) in 6 families (9.1%). Combining haplotype analysis and PCR-SSCP screening, 18 (15%) healthy female carriers were identified. The prevalence rate of germline BRCA1 gene mutations among our families with breast cancer syndrome is low, and relatives having the same haplotype for the 17q21 region as mutation-carrying patients usually display the same genomic sequence as the patients.