Homozygous deletion at the 9q32-33 candidate tumor suppressor locus in primary human bladder cancer.

Loss of heterozygosity (LOH) on chromosome arm 9q is the most frequent genetic alteration found in superficial and invasive transitional cell carcinoma (TCC) in a previous microsatellite-based deletion mapping study of the bladder and upper urinary tract, indicating the presence of one or more important tumor suppressor genes (TSGs). One of the putative tumor suppressor loci on 9q (DBC1) was mapped to 9q32-33 and the candidate region was localized within a single YAC. We report here a case of superficial papillary TCC, which showed a homozygous deletion encompassing this candidate tumor suppressor region. The region of homozygous deletion spanned the interval between D9S275 and AFMA239XA9 at 9q32-33, and was estimated to be </=6 cM. Although homozygous deletion mapping did not narrow down the candidate tumor suppressor region, this case provides further support for the presence of a TSG for TCC in this chromosomal region. To our knowledge, this is the first report to show homozygous deletion at 9q32-33 in TCC or any other type of human tumor. Genes Chromosomes Cancer 26:171-175, 1999. Copyright 1999 Wiley-Liss, Inc.