FAMILIAL MALE BREAST-CANCER IS NOT LINKED TO THE BRCA1 LOCUS ON CHROMOSOME 17Q

Breast cancer in men is about a hundredfold less common than in women and this has hindered research into its genetic basis. We have examine d 22 families with at least one case of male breast cancer for linkage to the hereditary breast and ovarian cancer locus, BRCA1, on chromoso me 17q. We found strong evidence against linkage to BRCA1 (led score - 16.63) and the best estimate of the proportion of linked families was 0% (95% Cl 0-18%). Our results indicate that there is a gene(s) other than BRCA1 which predisposes to early-onset breast cancer in women an d which confers a higher risk of male breast cancer. Identification of additional pedigrees that include cases of male breast cancer may the refore facilitate the mapping and isolation of this gene.