LOSS OF HETEROZYGOSITY IN SPORADIC ESOPHAGEAL TUMORS IN THE TYLOSIS ESOPHAGEAL CANCER (TOC) GENE REGION OF CHROMOSOME 17Q

From the genotyping of UK and US tylotic families with a high risk of oesophageal cancer we have previously localized the tylosis-associated cancer susceptibility gene (TOC gene, tylosis oesophageal cancer gene ) to a 1 cM region on the long arm of chromosome 17 (Kelsell et al,, 1 996), In the present study we investigated loss of heterozygosity (LOH ) patterns of 35 sporadic squamous cell carcinomas of the oesophagus u sing six polymorphic microsatellite markers encompassing this locus. T wenty-four of the 35 cases (69%) revealed LOH at one or more loci. Del etion was most frequently observed with the marker D17S801 (64% LOH, i nformative cases), which shows significant linkage to the TOC locus. T he LOH analysis in sporadic oesophageal cancer we report here is thus consistent with the hypothesis that the tylosis oesophageal cancer sus ceptibility gene is also involved in the pathogenesis of a proportion of sporadic squamous cell carcinomas of the oesophagus.