A Deletion Unit on Chromosome 17q in Epithelial Ovarian T\imors Distal to the Familial Breast/Ovarian Cancer Locus

Materials and Methods Linkage analysis in familial breast and ovarian cancer and studies of Tissue Samples and DNA Extraction. OvarÃ-an tumor tissue samples were allelic deletion in sporadic ovarian tumors have suggested that chromo some 17q may be the location of a gene of importance in ovarian cardilogenesis. We have examined tumor and normal DNA samples from 120 patients with ovarian tumors for allelic deletion at 12 loci on chromosome 17q. Allelic deletion was observed in 64 cases (53%) of which 56 showed loss of heterozygosity at all loci analyzed on 17q. The pattern of alÃ-eleloss at metastatic sites was consistent with loss of heterozygosity having oc curred prior to metastasis. A common region of deletion, defined by 6 cases of invasive epithelial ovarian cancer and a benign serous cystadenoma, spanned 16 cM and was delimited by nm23 and (¡II.This region is distal to the region on chromosome 17q to which the familial breast/ovarian cancer susceptibility gene has been mapped. The results suggest that a tumor suppressor gene involved in sporadic ovarian carcinogenesis is located on the distal portion of chromosome 17q and is distinct from the gene linked to familial cases.