Homozygous deletions of 9p21 in primary human bladder tumors detected by comparative multiplex polymerase chain reaction.

Deletion mapping studies of primary bladder tumors have identified nonoverlapping areas of loss on each arm of chromosome 9, indicating that two distinct tumor suppressor loci are located on this chromosome. The deleted region on the p arm overlaps an area of 9p previously reported to be lost in a variety of neoplasms. Detailed loss of heterozygosity analysis of 9p in 112 primary bladder tumors using 12 microsatellite markers identified a minimal area of loss around the alpha-interferon locus at 9p21-22. Frequent homozygous deletions of the alpha-interferon locus were then identified in these tumors by a novel, comparative, multiplex polymerase chain reaction assay and were subsequently confirmed by Southern analysis. Based on these deletions, a putative tumor suppressor gene locus involved in bladder tumorigenesis was localized to a 10 cM region (flanked by D9S162 and D9S171), previously implicated in the progression of many neoplasms. Application of the multiplex polymerase chain reaction-based assay will allow rapid identification of homozygous deletions in many neoplasms and thus aid in mapping studies of critical suppressor genes.