A novel region of deletion on chromosome 6q23.3 spanning less than 500 Kb in high grade invasive epithelial ovarian cancer

Detailed deletion mapping of chromosome 6q sequences in invasive ovarian tu mors have implicated several broad regions involving 6q14- 16, 6q21 -23, 6q 25 -26, and the telomeric portion in band 6q27 as regions of frequent loss in this malignancy. In order to define regions of loss involved in the deve lopment of ovarian cancer, we used 23 polymorphic markers on 6q to examine allelic loss in 25 high-grade, late stage ovarian tumors. Four nonoverlappi ng deletion regions were observed: (1) at 6q21-22.3 (D6S301-D6S292); (2) wi thin a 1 cM region at 23.2-23.3 between markers D6S978-D6S1637 (at D6S311); (3) at 6q26 (between markers D6S411-D6S1277) and (4) at 6q27 with the mark ers D6S297 and D6S193. The highest region of loss was observed with marker D6S311 (lost in 17 of 19 informative cases, 89%) in 6q23.3, followed by D6S 977 and D6S1637 (71 and 55%, respectively). The average fractional allele l oss in the high-grade tumors was around 35%. Previous reports have shown 6q 27 as the region of most frequent loss in invasive ovarian cancer. However, our results indicate a novel region in 6q23.3 (spanning less than 500 Kb d istance between the markers) with the highest loss, implicating this region of chromosome 6q to harbor a putative tumor suppressor gene involved in th e development of invasive epithelial ovarian cancer.