LOSS OF HETEROZYGOSITY ON THE X-CHROMOSOME IN HUMAN BREAST-CANCER

The analysis of loss of heterozygosity (LOH) in tumours can be a power ful tool for mapping the sites of tumour suppressor genes in the human genome. A panel of breast cancer patients was assembled as pairs of t umour and lymphocyte DNA samples and LOH studies carried out by Southe rn hybridisation with polymorphic loci mapping to the X chromosome wit h appropriate controls, Deletion mapping revealed a high frequency of small regionalised deletions, defining at least three independent regi ons, one of which is particularly well mapped to a 500 kb stretch of D NA in the distal portion of the pseudoautosomal region of Xp. A second region has been identified within the pseudoautosomal region close to the pseudoautosomal boundary, and there is a third discrete site of l oss on distal Xq. Perturbations of sequences at these regions represen t independent events in a number of patients, This study represents th e first detailed analysis of LOH on the X chromosome in human breast t umours, the results of which indicate that at least three regions of t his chromosome are involved in the disease. 1995 Wiley-Liss, Inc.