COMPARATIVE GENOMIC IN-SITU HYBRIDIZATION OF COLON CARCINOMAS WITH REPLICATION ERROR

The aim of the present study was to detect complex; genetic alteration s in colorectal carcinomas with and without microsatellite instability (MIN) by comparative genomic in situ hybridization, MIN due to replic ation errors is the hallmark of hereditary nonpolyposis colon cancer, None of 6 MIN-positive tumors showed amplifications, and only 2 tumors displayed deletions of one chromosomal segment each, In contrast, dif ferent gains and losses were observed in 11 of 12 MIN-negative carcino mas, The most frequent gains affected chromosomes 7, 13, and 20q, wher eas deletions were observed on chromosomes 17, 18, and 9p, These resul ts demonstrate different mechanisms of genetic instability in subgroup s of colorectal carcinomas and may, therefore, support the hypothesis of different etiologies in tumors with and without MIN.