Commonly deleted regions on the long arm of chromosome 21 in differentiated adenocarcinoma of the stomach.

During an allelotype analysis of differentiated adenocarcinoma of the stomach, we observed frequent loss of heterozygosity (LOH) on several chromosomes including the long arm of chromosome 21 (21q). Therefore, we analyzed DNA isolated from 45 tumors for LOH at 10 loci on 21q by using polymorphic microsatellite markers. In 20 (44%) of 45 tumors, we detected LOH at single or multiple loci on 21q. Deletion mapping of these 20 tumors revealed two separate commonly deleted regions. Our findings suggest that 21q contains at least two potential tumor suppressor genes which play crucial roles in the development of differentiated adenocarcinoma of the stomach.