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Differences in the frequencies of K‐ras c12–13 genotypes by gender and pathologic phenotypes in colorectal tumors measured using the allele discrimination method
Author(s) -
Chow Lihui,
Lin PengChan,
Chang Jeffrey S.,
Chu PeiYi,
Lee PaoKung,
Chen ShanNa,
Cheng YingMin,
Lee JenqChang,
Chang JangYang,
Liu TsangWu
Publication year - 2012
Publication title -
environmental and molecular mutagenesis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1
H-Index - 87
eISSN - 1098-2280
pISSN - 0893-6692
DOI - 10.1002/em.20673
Subject(s) - genotyping , genotype , biology , allele , polymerase chain reaction , colorectal cancer , mutation , genetics , allele frequency , microbiology and biotechnology , cancer , gene
The frequencies of different genotypes of the K‐ras oncogene in colorectal cancer (CRC) reveal complex relationships among gender, age, and tumor aggression, however, differences among these studies could also be attributed to a lack of standardization of the detection methods used. We developed the allele discrimination assay, which uses dual‐color real‐time polymerase chain reaction (qPCR) as a fast K‐ras genotyping method, and demonstrated higher sensitivity and specificity than DNA sequencing with formalin‐fixed paraffin tissues. The assay detected K‐ras mutations among 83 of 204 patients with CRC (40.7%); 20.6% of these mutations were G12D (GAT) mutations, 7.4% were G13D (GAC) and G12V (GTT), and 5.3% were other types. A higher proportion of females was observed overall in tumors with K‐ras mutations (60.2%, P = 0.01), codon 12 mutations (63.2%, P = 0.005), and transversions (69.6%, P = 0.02), which reflected the higher prevalence of females among the well‐ to moderately differentiated tumors (29% in males vs. 53% in females; interaction P = 0.03). The opposite was observed for poorly differentiated tumors (47% in males vs. 35% in females). No significant influence of age was found on the prevalence of K‐ras mutation. Males with pathological changes and females with poorly differentiated tumors displayed GAT as a less common genotype compared with most other prevalence studies. In conclusion, allele discrimination, with no additional amplification step, is a fast and reliable genotyping method for detecting K‐ras c12–13 mutations. Using this method, we demonstrate differences in the frequencies of K‐ras genotypes by gender and pathologic phenotypes of CRC. Environ. Mol. Mutagen., 2012. © 2011 Wiley‐Liss,Inc.