Distinct regions of allelic loss on chromosome 4 in human primary bladder carcinoma.

Accumulating evidence implicates the presence of putative tumor suppressor genes on human chromosome 4 that are potentially inactivated in the genesis of several different neoplasms. To accurately determine the frequency of allelic loss on both arms of human chromosome 4, we screened 282 fresh-frozen human bladder carcinomas for allelic loss. Loss of heterozygosity of at least one marker for chromosome 4 was identified in 129 tumors (45.7%). Fine mapping was accomplished using up to 15 polymorphic markers on the p arm and 19 markers on the q arm. We identified a 3-cM minimal area of loss on the p arm between microsatellite markers D4S1608 and D4S404 deleted in 82 tumors (29%). A total of 68 tumors (24%) targeted a 14-cM critical region identified on the distal q arm between markers D4S426 and D4S408. Loss of these two regions correlated with advanced stage and grade of the lesions. These data identify distinct regions of loss on chromosome 4 potentially involved in the late progression of bladder carcinoma.