Susceptibility to Colorectal Cancer and Two Genetic Polymorphisms of XRCC4

The X-ray complementing group 4 (XRCC4, OMIM: 194363) plays a key role in non-homologous end-joining DNA repair pathway in mammalian cells. This pathway is believed to help maintain genomic stability. In the present study, it is hypothesized that genetic polymorphisms in the NHEJ repair XRCC4 gene may be associated with an increased risk in developing colorectal cancer (CRC). We genotyped two polymorphisms of XRCC4, G-1394T (rs6869366) and intron 3 insertion/deletion (I/D; rs28360071) in 200 colorectal cancer patients as well as 256 healthy individuals, and evaluated their association with CRC. We found that in G-1394T polymorphism, neither the TG nor the GG genotypes (versus the TT genotype) were associated with the risk of developing CRC. The results of our study indicate that in comparison with the II genotype, ID and DD genotypes had no significant association with the risk of developing CRC. Subjects with TT genotype and positive family history in colorectal cancer were found to be at a much lower risk of developing CRC in comparison with the reference group (OR = 0.31, 95%CI: 0.11-0.85, P =  .023). It should be noted that participants having at least one G allele (TG+GG genotypes) were at a significantly higher risk to develop the disease compared with the reference group (OR = 9.10, 95%CI: 2.00-41.3, P = 0.004). In relation to I/D polymorphism, among participants, those with positive family history, either with ID (OR =  .78, 95%CI: 2.26-10.0, P < 0.001) or DD genotypes (OR = 5.73, 95%CI: 1.99-16.4, P = 0.001) had a significantly association with the disease. Among participants with a positive family history in CRC, the haplotype GD dramatically increased the risk of developing CRC (OR = 10.2, 95%CI: 2.28-46, P = 0.002). The results of this study indicate that G-1394T and I/D polymorphisms of XRCC4 among individuals with positive family history for colorectal cancer substantially increase the risk factor for developing colorectal cancers.