High frequency of chromosome 9 deletion in ovarian cancer: Evidence for three tumour-suppressor loci

We have screened 33 ovarian tumours of various grades and stages for loss of heterozygosity (LOH) of markers on chromosome 9. LOH was detected in 26 cases (79%). Eleven tumours (33%) showed LOH of all informative markers. The remaining 15 cases had partial deletions. Of these, six (18%) had losses on 9p only, three (9%) had LOH confined to 9q and six (18%) had losses on both chromosome arms, four of which had a region of retention of heterozygosity in between. There was no association between tumour grade, stage or histopathology and any losses. High-density deletion mapping was carried out in 12 selected cases that had partial deletions of 9p and/or 9q. The deleted region on 9p incuded the cyclin-dependent kinase inhibitor 2 (CDKN2) locus and one tumour was found to have a homozygous deletion of CDKN2. LOH on 99 extended over a larger region. We found evidence for two regions of deletion on 9q, one at 9q34 and the other encompassing the nevoid basal cell carcinoma (Gorlin) syndrome locus on proximal 9q.