LINKAGE ANALYSIS OF 26 CANADIAN BREAST AND BREAST-OVARIAN CANCER FAMILIES

We have examined 26 Canadian families with hereditary breast or ovaria n cancer for linkage to markers flanking the BRCA1 gene on chromosome 17q12-q21. Of the 15 families that contain cases of ovarian cancer, 94 % were estimated to be linked to BRCA1. In contrast, there was no over all evidence of linkage in the group of 10 families with breast cancer without ovarian cancer. A genetic recombinant in a breast-ovarian can cer family indicates a placement of BRCA1 telomeric to D17S776, and he lps to define the region of assignment of the cancer susceptibility ge ne. Other cancers of interest that appeared in the BRCA1-linked famili es included primary peri-toneal cancer, cancer of the fallopian tube, and malignant melanoma.