The Association Of Rad51Polymorphism With The Risk Of Colorectal Cancer

Objective: To explore the relationship of DNA repair gene Rad51twocommon sites rs1801320G/C and rs1801321G/T polymorphisms with the riskof colon cancer and rectal cancer in Hebei province of China using a case-control study.Methods：This experiment adopted the case-control study method, with51cases of colon cancer patients,78cases of rectal cancer patients and70cases of healthy subjects as the research object.Under the condition of asepsis5ml peripheral blood was obtained from each subject. DNA was extractedfrom the peripheral venous using Proteinase K digestion-saturated chlorine ofsodium salt method. Rs1801320G/C and rs1801321G/T were amplified invitro and the genotypes were analyzed by polymerase chain reaction-ligasedetection reaction (PCR-LDR) method.Using SPSS13.0software for statistical analysis of experimental data,it wasconsidered statistically significant when P<0.05.The chi-square test wasadopted to perform frequency Hardy Weinberg equilibrium analysis in controlgenotype. The chi-square test was adopted to analyze and compare the thegenotype and allele distribution between the experimental and control groups.Using EH software and2LD software to analysis the haplotype frequenciesand linkage disequilibrium. Using unconditioned Logistic regression methodto calculate the odds ratio of the relative risk degree and95%confidenceinterval.Results：1The polymorphic genotype frequencies distribution of Rad51rs1801320G/C and rs1801321G/T in control group were in line with the Hardy-Weinb-erg equilibrium (P＞0.05).2Rad51gene rs1801320G/C gene polymorphism G and C allele freque- ncy in rectal cancer group and control group were：77.6%,22.4%and88.5%,11.5%, comparing the two groups, the P value was0.011, and consideredstatistically significant, indicating rs1801320C allele could increase the riskof rectal cancer. G/G, C/G, C/C genotype frequency in rectal cancer group andthe control group were:65.4%,24.4%,10.3%and78.4%,20.3%,1.4%,comparing the two groups, the P value was0.647, without statisticalsignificance. But rectal cancer patients group with C/C genotype frequency(10.3%) was significantly higher than control group (1.4%). Compared withG/G genotype, it could increase the risk of rectal cancer (OR=8.659,95%CI=1.002~78.423).3Rs1801320G/C polymorphism G and C allele frequency in the colonexperimental group and the control group were87.3%,12.7%and88.5%,11.5%, comparing the two groups, the P value was0.763, without statisticalsignificance. In the colon cancer patients experimental group and the controlgroup, G/G, C/G, C/C,genotype frequency were:76.5%,21.6%,2.0%and78.4%,20.3%,1.4%, comparing the two groups, the P value was0.350,,considered no statistical significance.4In the colon cancer experimental group and the control group,rs1801321G/T G and T allele frequency were95.1%,4.9%and97.3%,2.7%,comparing the two groups, the P value was0.359, considered no statisticalsignificance. In the rectal cancer patients experimental group and the controlgroup, rs1801321G/T G and T allele frequencies were98.1%,1.9%and97.3%,2.7%, comparing the two groups, the P value was0.651, considered nostatistical significance. In the colon cancer group and the control group, G/Tand G/G genotype frequency were:9.8%,90.2%and5.4%,94.6%,in therectal cancer experimental group and the control group, G/T and G/Ggenotype frequency were:3.8%,96.2%and5.4%,94.6%, comparing the twogroups by each, the P values were0.350and0.649, there were no statisticalsignificance. Compared with the G/T genotype, no significant were observedbetween G/G genotype and colon cancer risk(OR=0.570,95%CI=0.128~2.539), the same between G/G and colorectal cancer risk (OR=1.538,95%CI =0.286~8.270).5In colon cancer and normal control experimental groups, the linkagedisequilibrium was observed (’ D=0.165) between Rad51rs1801320andrs1801321, but according to the results, the interaction of rs1801320G/C andrs1801321G/T has no correlation with the risk of colon cancer.6In rectal cancer and normal control experimental groups, the linkagedisequilibrium was observed (’ D=0.401) between Rad51rs1801320andrs1801321, the most common haplotype was rs1801320G-rs1801321G, thefrequency in rectal cancer group and normal control group were75.6%and87%, followed by rs1801320C-rs1801321G (22.4%,10.3%) and rs1801320G-rs1801321T (1.9%,1.5%), the proportion of rs1801320C-rs1801321T is thelowest in the crowd(0.0%、1.2%). Rs1801320C-rs1801321G haplotypeincreased the risk of rectal cancer (OR=2.514,95%CI=1.313~4.814),whereas rs1801320G-rs1801321G haplotype would reduce the risk of rectalcancer (OR=0.465,95%CI=0.255~0.849). No relevance was observedbetween the interaction of rs1801320G-rs1801321T and rs1801320C-rs1801321T and colorectal cancer risk.Conclusions:1Rad51gene rs1801320G/C SNP and rectal cancer risk in Hebeiprovince of China was relevant, compared with the G/G genotype, the C/Cgenotype could increase the risk of rectal cancer, carrying C allele mayincrease the risk of rectal cancer. No correlation was observed betweenrs1801320G/C SNP and the risk of colon cancer in Hebei province of China.2No correlation was observed between Rad51gene rs1801321G/T SNPand the risk of colorectal cancer in Hebei province of China.3In the colon cancer experimental group and the normal control group,the phenomenon of linkage disequilibrium was observed (’ D=0.165)between Rad51gene5’UTR rs1801320G/C and rs1801321G/T, but itshaplotype and the risk of colon cancer have no relevance.4In the rectal cancer and normal control groups, the phenomenon oflinkage disequilibrium was observed(’ D=0.401) between rad51gene5’UTR rs1801320G/C and rs1801321G/T, rs1801320C-rs1801321G haplotypeincrease the risk of rectal cancer(OR=2.514,95%CI=1.313~4.814), butrs1801320G-rs1801321G haplotype may reduce the risk of rectal cancer(OR=0.465,95%CI=0.255~0.849), other haplotype may have no relationshipwith the risk of rectal cancer.