K-ras activation in colorectal tumors from patients with familial polyposis coli.

K-ras gene mutation in colorectal tumors from patients with familial polyposis coli were investigated using oligonucleotide probes specific for a mutation at codon 12, 13, or 61 of the K-ras gene. The authors examined 22 colorectal carcinomas and 51 colorectal adenomas from 41 familial polyposis coli patients and observed mutations at codons 12 and 13 in eight of 22 colorectal carcinomas (36%) and six of 51 colorectal adenomas (12%). Thus, the frequency and sites of K-ras gene mutation in colorectal carcinoma from familial polyposis coli patients are similar to those in cases of sporadic colorectal carcinoma and may not be the first genetic event linked to the tumorigenesis.