Genetic Polymorphisms in the DNA Repair Enzyme ERCC2 and Breast Tumour Risk in a Chinese Population

Analysis of ERCC1 and ERCC2 gene variants in osteosarcoma, colorectal and breast cancer

The Asn118Asn (rs11615) variant in the ERCC1 gene, and the Lys751Gln (rs13181) and Asp312Asn (rs1799793) variants in the ERCC2 gene have been associated with the development of varied types of cancer. The aim of the present study was to test for any association between the ERCC1 and ERCC2 gene variants and three different types of cancer in Mexican-mestizo patients. Patients and their respective controls were formed into three groups: The osteosarcoma group, with 28 patients and 97 controls; the colorectal group, with 108 patients and 119 controls; and the breast cancer group, with 71 patients and 74 controls. Genotyping was performed using TaqMan probes and quantitative polymerase chain reaction. Allele and genotype frequencies were compared using a χ² test. Only one SNP (rs1799793) was found to be associated with breast cancer. This is the first study analyzing the SNPs in ERCC1 and ERCC2 genes and the susceptibility to cancer in Mexican-mestizo patients with osteosarcoma, and colorectal and breast cancer.

Genetic polymorphisms associated with breast cancer in malaysian cohort

Genome-wide association studies have discovered multiple single nucleotide polymorphisms (SNPs) associated with the risk of common diseases. The objective of this study was to demonstrate the replication of previously published SNPs that showed statistical significance for breast cancer in the Malaysian population. In this case-control study, 80 subjects for each group were recruited from various hospitals in Malaysia. A total of 768 SNPs were genotyped and analyzed to distinguish risk and protective alleles. A total of three SNPs were found to be associated with increased risk of breast cancer while six SNPs showed protective effect. All nine were statistically significant SNPs (p ≤ 0.01), five SNPs from previous studies were successfully replicated in our study. Significant modifiable (diet) and non-modifiable (family history of breast cancer in first degree relative) risk factors were also observed. We identified nine SNPs from this study to be either conferring susceptibility or protection to breast cancer which may serve as potential markers in risk prediction.

Meta-analysis of two ERCC2 (XPD) polymorphisms, Asp312Asn and Lys751Gln, in breast cancer

The excision repair cross-complementing group 2 gene (ERCC2) plays a key role in DNA repair. Several polymorphisms in the ERCC2 gene have been described, including the commonly occurring Lys751Gln and Asp312Asn polymorphisms. Studies investigating the association of these polymorphisms with breast cancer risk produced controversial results. To evaluate these associations presented in diverse populations, we have conducted a meta-analysis based on 40 studies from 33 publications in PubMed which included analyses of Lys751Gln (14,545 cases, 15,352 controls) and Asp312Asn polymorphisms (16,254 cases, 14,006 controls). Overall findings of both polymorphisms have implicated null effects (OR = 1.01-1.03) when the analyses were limited to the statistically powerful (≥80%) studies. Although modestly increased statistically significant breast cancer risk was detected in the underpowered studies (≤80%), removal of outliers resulted in null associations. Ethnic stratification showed non-significant and relatively null associations for both polymorphisms with breast cancer risk for the overall Caucasians as well as North American and the European sub-populations. Although statistically increased and decreased risks were observed for the homogenous populations of African-Americans (Lys751Gln, OR 1.25, 95% CI 1.03-1.53, P = 0.03) and Asians (Asp312Asn, ORs: 0.53-0.55, P values: 0.02-0.03), respectively, this may be the result of small sample size. Analyses of the homogeneous adduct studies, with relatively large sample size, exhibited increased risk for Lys751Gln (OR 1.20, 95% CI (1.02-1.41), P = 0.03) and Asp312Asn (OR 1.17 95% CI 1.02-1.34, P = 0.03) under the dominant genetic model. In conclusion, our results suggest null associations of both polymorphisms in the overall and the Caucasian subgroups, although some effects can be suggested for relatively smaller minority studies. Increased risk effect was more visible when the adduct studies are considered, suggesting the role of these polymorphisms in the presence of exposure to DNA damaging agents.

Associations between XPD polymorphisms and risk of breast cancer: a meta-analysis

Studies on polymorphisms of Xeroderma Pigmentosum Group D Protein (XPD) and breast cancer risk are inconclusive. To elucidate the role of XPD genotypes, all available studies were considered in this meta-analysis. The study provided 11,362/10,622 cases/controls for XPD K751Q and 9010/9873 cases/controls for XPD D312N, respectively. Overall, no apparent effects of 751Q allele compared to 751K on breast cancer risk was found in all subjects [RE OR = 1.04, 95% confidence interval (CI) (0.97-1.10), P = 0.28]. Insignificant effects were also found under other genetic contrasts (homologous contrast, dominant model, and recessive model). However, the 751Q allele showed significantly increased risk in Caucasians [FE OR = 1.05, 95% CI (1.00-1.11), P = 0.035]. In addition, insignificant risk effects of D312N polymorphism on breast cancer susceptibility were observed in all subjects under any genetic contrast, but protective effects of 312NN genotype were observed under recessive model [P = 0.02, OR = 0.53, 95% CI (0.32, 0.90)] and homozygote contrast [P = 0.03, OR = 0.55; 95% CI (0.32, 0.96)] in Asians. In summary, our meta-analysis suggested 312N allele might act as a recessive allele in its association with breast cancer and the 751Q allele may play a plausible role in breast cancer development whereas the ethnic background should be carefully concerned in further studies.