No heterogeneity or discordance between studies was observed for three KRAS sub-type mutations in CRC patients (I2 = 27%, test for overall effect P = 0.45 for codon12+13, I2 = 0%, P = 0.19 for codon12 and I2 = 0%, P = 0.55 for codon13). The gene discussed is KRAS; the disease is colorectal carcinoma.