THE GENE FOR HEREDITARY BREAST-OVARIAN CANCER, BRCA1, MAPS DISTAL TO EDH17B2 IN CHROMOSOME REGION 17Q12-Q21

A gene for hereditary breast and ovarian cancer, BRCA1, has been mappe d to chromosome 17q12 - q21. This gene is responsible for cancer susce ptibility in the majority of families with multiple cases of ovarian c ancer and early-onset breast cancer. We report linkage results of a fa mily with 10 cases of breast cancer and a single case of ovarian cance r. A recombinant event in this family places BRCA1 distal (telomeric) to the locus EDH17B2, which codes for the enzyme estradiol 17 beta-deh ydrogenase II. This recombinant is based on the appearance of breast c ancer in a 45 year old woman. Under our genetic model, we estimate the probability that this woman carries a BRCA1 mutation to be 94%. These data further reduce the region of assignment of BRCA1 on chromosome 1 7q12 - q21 and should expedite positional cloning of this important ge ne.