Single Nucleotide Polymorphism (K589E) of the EXO1 Gene: Association with Colorectal Cancer Susceptibility and Clinicopathological Features

Background and aim: Exonuclease1 (EXO1) is a member of the RAD2 nuclease family which is involved in mismatch repair (MMR) system and contributes to the maintenance of genomic stability, modulation of DNA recombination and cell cycle arrest mediation. K589E (rs1047840) as a potentially functional polymorphism in EXO1 gene may alter cancer risk by influencing its repair activity. Method: We designed a case-control study consisting of 319 subjects with colorectal cancer (CRC) and 310 healthy controls to investigate the effect of K589E polymorphism on CRC susceptibility and clinicopathological features in an Iranian population. Genotype determination was performed by PCR-RFLP method. Results: We provided the first evidence that there is not any significant association between EXO1 K589E alleles and genotypes and risk of CRC, even after adjustment for sex, age and smoking status (OR=1.033; 95% CI 0.814-1.312). Also analysis of clinicopathological characteristics and genotype distribution did not show any significant correlation. Conclusion: Despite the well-known role of EXO1, our results revealed that EXO1 K589E polymorphism could not be a potential predisposing risk factor in genetic susceptibility to CRC, at least in the studied population. A large scale case-control study will need to be carried out to further validate this polymorphism as a noncontributor to the risk of CRC in Iranian population.