In this work, an attempt was made to identify genetic variants that make people more susceptible to CRC, especially those in the cytochrome genes that play a role in phase I PAH metabolism namely; CYP1A1 (rs1048943 and rs4646903) CYP1B1 (rs1056836) (Ghisari et al., 2014). The gene discussed is CYP1A1; the disease is colorectal carcinoma.