The Frequency and Spectrum of K-ras Mutations among Iraqi Patients with Sporadic Colorectal Carcinoma (CRC)
Iraqi Postgraduate Medical Journal,
2017, Volume 16, Issue 1, Pages 18-24
CRC is one of the most common cancers in the world. K-ras is proto-oncogene with GTPase activity that is lost when the gene is mutated. Analysis of K-ras mutational status is very important for CRC treatment, being the most important predictors of resistance to targeted therapy.
This study aims to determine the frequency and spectrum of K-ras mutation among Iraqi patients with sporadic CRC.
PATIENTS, MATERIALS AND METHODS:
This study enrolled 35 cases with sporadic CRC; their clinicopathological parameters were analyzed. The FFPE blocks were used for DNA extraction; PCR amplification of K-ras gene and hybridization of allele-specific oligoprobes were performed. The assay covers 29 mutations in the K-ras gene (codons 12, 13, 59, 60, 61, 117 and 146).
The majority of cases have left colonic tumours (57%), without LN involvement (57.1%), of non-mucinous adenocarcinoma histology (85.7%), grade II (82.9%) and stage III (37.1%) tumours. Fourteen mutations were detected in 13 (37%) patients with K-ras mutations; 10 (71.4%) mutations were in codon 12 while 4(28.6%) were in codon 13. The most frequent mutation was the G>T transversions [9 (64.4%)] and the most frequent mutation type was GGT>TGT (GLY>CYS) at codon 12.
The incidence of K-ras mutations lies in the middle of the reported figures worldwide; the majority of mutations occurred at codon 12 followed by codon 13; predominantly of G>T transversion and Gly12Cys type that has a poorer prognosis.
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