COMMONLY DELETED REGION ON THE LONG ARM OF CHROMOSOME-7 IN DIFFERENTIATED ADENOCARCINOMA OF THE STOMACH

Loss of heterozygosity (LOH) at several chromosomal loci is a common e vent in human malignancies. Frequent LOH on the long arm of chromosome 7 has been reported in various human malignancies, and investigators have identified the most common site of LOH as 7q31.1. We have identif ied ten chromosomal loci, including chromosome 7q, that have been show n by previous allelotype study to be sites of frequent LOH in differen tiated adenocarcinoma of the stomach. In the present study, we perform ed a polymerase chain reaction (PCR) microsatellite analysis to define the common deleted region on 7q, using 14 polymorphic microsatellite markers in matched tumour and non-tumour DNAs from 53 patients with pr imary gastric carcinoma of the differentiated type. LOH at any locus o n 7q occurred in 34% (18 out of 53) of the tumours. Although many tumo urs exhibited total or large interstitial deletions, we determined the smallest common deleted region to be at D7$480 (7q31.1). This is iden tical to the region identified for other human malignancies. These obs ervations indicate that a putative tumour suppressor gene at 7q31.1. m ay be involved in the pathogenesis of differentiated adenocarcinoma of the stomach.