DETAILED DELETION MAPPING OF CHROMOSOME SEGMENT 17Q12-21 IN SPORADIC BREAST-TUMORS

Linkage studies have indicated that a gene on chromosome arm 17q, desi gnated BRCA1, confers susceptibility to familial breast and ovarian ca ncer. To investigate the possible involvement of the BRCA1 gene in spo radic breast cancer we have analysed loss of heterozygosity (LOH) in a panel of 100 sporadic primary breast tumours using 10 PCR-based polym orphic markers from 17q12-21. Allele losses were detected in 40 of 100 tumours informative for at least one of the markers analysed. Of thes e 40 deleted tumours, 27 showed partial or interstitial loss on 17q. T he pattern of LOH in the tumours with partial or interstitial LOH reve aled three putative distinct deleted regions on 17q12-21. The first li es on the proximal long arm between D17S250 and THRA1; the second one lies between D17S776 and D17S579, the region containing the BRCA1 gene ; and the third is telomeric to D17S733. The most frequently deleted r egion overlaps with the minimal region containing the BRCA1 gene, sugg esting that this gene might also be associated with the development or progression of a proportion of sporadic breast tumours. (C) 1994 Wile y-Liss, Inc.