• Keping Zhang, Jie Xu, Lixu Yan, Xunhua Liu, Fangping Xu, and Yanhui Liu.
• Department of Pathology, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou 510010, China.
• Zhonghua Bing Li Xue Za Zhi. 2015 Apr 1; 44 (4): 254-7.

ObjectiveTo investigate mutations frequencies of KRAS,NRAS and BRAF genes in colorectal carcinoma.MethodsTissue specimens from 200 colorectal cancer patients at diagnosis were collected and subject to KRAS,NRAS and BRAF mutation analyses by PCR-based direct DNA sequencing targeting exons 2, 3 and 4 of KRAS gene, exons 2, 3 and 4 of NRAS gene and exon 15 of BRAF gene.ResultsActivating mutations were detected in KRAS (44%, 88/200), NRAS (2%, 4/200) and BRAF (5%, 10/200) in this study cohort.Among KRAS mutations, 64.8% (57/88) occurred in codon 12 and 12.5% (11/88) occurred in codon 13. KRAS gene mutation in exon 3 mainly involved codons 59 and 61. KRAS gene mutation in exon 4 mainly involved codons 117 and 146.ConclusionsMutations at exon 2 of KRAS gene have the highest frequency in colorectal carcinoma. Expanding the detection sites of KRAS gene combined with NRAS and BRAF genes may help to identify patients who will most likely benefit from targeted therapies.

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