TOWARDS A 2ND-GENERATION ALLELOTYPE OF CO LON-CANCER

A subset of genetic alterations distinguishes two groups of colon canc ers. In the first group instability of micro-satellite loci due to a d efective DNA mismatch repair system is observed. The second group is c haracterized by recurrent losses of chromosome regions, frequently ass ociated with hyperploidization. We have developed a technique which en ables a fine description of allelic losses in this second group of tum ours. The typing of 278 loci in 47 hyperploid colon cancers has provid ed information for an average of 160 loci per tumour. The high frequen cy of allelic losses on chromosomes 17, 18 and 5 was confirmed thus va lidating our methodological approach. Several additional chromosome se gments were observed lost in over 40% of the cases, suggesting that tu mour suppressor genes may map within these regions. Further technical development should contribute to the identification of these genes.