LINKAGE STUDIES WITH 17Q AND 18Q MARKERS IN A BREAST OVARIAN-CANCER FAMILY

Genes on chromosomes 17q and 18q have been shown to code for putative tumor suppressors. By a combination of allele-loss studies on sporadic ovarian carcinomas and linkage analysis on a breast/ovarian cancer fa mily, we have investigated the involvement of such genes in these dise ases. Allele loss occurred in sporadic tumors from both chromosome 17p , in 18/26 (69%) cases, and chromosome 17q, in 15/22 (68%) cases. In t he three familial tumors studied, allele loss also occurred on chromos ome 17 (in 2/3 cases for 17p markers and in 2/2 cases for a 17q allele ). Allele loss on chromosome 18q, at the DCC (deleted in colorectal ca rcinomas) locus, was not as common (6/16 cases [38%]) in sporadic ovar ian tumors but had occurred in all three familial tumors. The results of linkage analysis on the breast/ovarian cancer family suggested link age between the disease locus and 17q markers, with a maximum lod scor e of 1.507 obtained with Mfd188 (D17SS79) polymorphism at 5% recombina tion. The maximum lod score for DCC was 0.323 at 0.1% recombination. I n this family our results are consistent with a predisposing gene for breast/ovarian cancer being located at chromosome 17q21.