Novel homozygous deletions of chromosomal band 18q22 in pancreatic adenocarcinoma identified by STS marker scanning

The identification of homozygous deletions in sporadic neoplasms has been pivotal in the positional cloning of several tumor suppressor genes. Chromosomal arm 18q harbors the DPC4, SMAD2, and DCC genes and is suspected on the basis of high frequencies of allelic loss to harbor additional tumor suppressor genes. We applied high-resolution sequence-tagged site (STS) marker scanning to a panel of 106 pancreatic adenocarcinomas to identify novel regions of homozygous deletions on 18q. Three homozygous deletions were identified. Physical mapping of these deletions showed them to be nonoverlapping, but clustered in an approximately 7- to 10-Mb region of chromosome band 18q22. Each deletion spanned physical distances of nearly 1.3 to 3 Mb. A number of transcribed genes map within these deletions. The identification of these homozygous deletions might aid in the identification of novel tumor suppressor genes on chromosomal arm 18q.