KRAS and colorectal carcinoma: Thus, the CRC clinical guideline urges for extended RAS mutation testing including KRAS and (NRAS) neuroblastoma RAS viral oncogene homolog in exon 2 (codons 12 and 13), exon 3 (codon 59 and 61), and exon 4 (codon 117 and 146) [19].