The frequency and spectrum of K-ras mutations among Iraqi patients with sporadic colorectal carcinoma

Abstract

The epidemiology of colorectal cancers (CRC) is well known to differ in different geographical regions. K-ras mutations have been implicated in CRC carcinogenesis and they were extensively studied in developed countries; however, such studies are scarce from developing countries, like Iraq. To determine the frequency and spectrum of K-ras mutations among CRC Iraqi patients, and their clinico-pathological associations, if any. Fifty consecutive surgically resected sporadic CRC were evaluated. The evaluation included screening for ten K-ras mutations in codon 12 and 13 by mutant enriched polymerase chain reaction followed by reverse hybridization to oligospecific probes. Out of the 50 enrolled patients, 24 (48%) had K-ras mutations. A total of 29 mutations were identified in the tumors of the latter 24 patients (20/24 tumors had single mutations, 3/24 had double mutations and 1/24 had triple mutations). The most frequently encountered mutations were the G>T transversions and G>A transitions (41.4% each). Codon 12 mutations constituted 89.7%, while codon 13 the remaining 10.3%. The most frequent mutation was GGT>GTT (Gly>Val) of codon 12 documented in 31%. No significant clinico-pathological correlations with K-ras mutational status were identified. The K-ras mutations are frequently encountered among Iraqi sporadic CRC patients, with relative higher frequencies of G>T transversions and Gly>Val codon 12 substitutions than encountered in their counterparts in developed countries. The latter is most likely to be related to differences in local carcinogens exposure, an aspect which requires further scrutiny.