LOSS OF HETEROZYGOSITY IN FAMILIAL BREAST CARCINOMAS

Three loci have been implicated in the etiology of familial breast can cer; the BRCA1 locus on 17q, the p53 gene on 17p, and the androgen rec eptor gene on the X chromosome. However, it has been estimated that in approximately 50% of all breast cancer families the predisposing gene tic defect is not linked to any of these three loci. In an attempt to identify chromosomal regions harboring putative breast cancer genes we performed allelotyping in 82 familial breast carcinomas. Polymorphic markers representing 45 different loci were analyzed and the most freq uently involved chromosomal arms were 8p, 16q, 17p, 17q, and 19p.