KRAS and colorectal carcinoma: The majority of the KRAS mutations in the CRC are located in codons 12 and 13 of exon 2 (80% are G12A, G12C, G12D, G12S, G12V, G13C, G13D), and less frequently in codon 61 of exon 3 (5% are Q61H, Q61L, and Q61R) and codon 146 of exon 4 (2% are A146T and A146V) [26].