The relationship between five widely-evaluated variants in CDKN2A/B and CDKAL1 genes and the risk of type 2 diabetes: A meta-analysis

The genes encoding two cyclin-dependent kinases-inhibitor-2A/B (CDKN2A/B) and 5 regulatory subunit-associated protein-like 1 (CDKAL1) have been investigated extensively in associations with type 2 diabetes; the results, however, are often irreproducible. We therefore sought to evaluate these associations by performing a meta-analysis on five widely-evaluated variants from the two genes. There were 38 studies (patients/controls: 51,940/52,234) for rs10811661, 16 studies (20,029/24,419) for rs564398 in CDKN2A/B gene, and 27 studies (28,383/47,635) for rs7756992, 26 studies (28,816/31,713) for rs7754840, 21 studies (29,260/38,400) for rs10946398 in CDKAL1 gene. Overall risk estimates for type 2 diabetes conferred by rs10811661-T, rs564398-A, rs7754840-C, rs7756992-G, and rs10946398-C alleles were 1.17 (95% CI: 1.10–1.23; P < 0.0005; I² = 83.9%), 1.1 (95% CI: 1.0–1.21; P = 0.051; I² = 88.3%), 1.24 (95% CI: 1.18–1.3; P < 0.0005; I² = 74.3%), 1.2 (95% CI: 1.11–1.3; P < 0.0005; I² = 92.0%), and 1.19 (95% CI: 1.1–1.29; P < 0.0005; I² = 90.8%), respectively. There was evident publication bias for rs564398 and rs7754840. Subgroup analyses by ethnicity showed remarkable divergences in risk estimate for rs564398 between Asians (odds ratio [OR] = 1.01; 95% CI: 0.86–1.19; P = 0.868) and Caucasians (OR = 1.19; 95% CI: 1.03–1.35; P = 0.012) (P < 0.05). For all variants examined, the results of studies in retrospective design or with population-based controls were comparative with that of overall studies. In meta-regression analyses, age was found to exert a significant influence on the association between rs10811661 and type 2 diabetes (P = 0.003), as well as between rs7754840 and gender (P = 0.034). Taken together, our findings provide evidence for a significant contribution of CDKN2A/B gene rs10811661 and CDKAL1 gene rs7756992 and rs10946398 to type 2 diabetes.     

Null genotypes of GSTM1 and GSTT1 contribute to increased risk of diabetes mellitus: A meta-analysis

Diabetes mellitus (DM) is a common disease which results from various causes including genetic and environmental factors. Glutathione S-Transferase M1 (GSTM1) and Glutathione S-Transferase T1 (GSTT1) genes are polymorphic in human and the null genotypes lead to the absence of enzyme function. Many studies assessed the associations between GSTM1/GSTT1 null genotypes and DM risk but reported conflicting results. In order to get a more precise estimate of the associations of GSTM1/GSTT1 null genotypes with DM risk, we performed this meta-analysis. Published literature from PubMed, Embase and China Biology Medicine (CBM) databases was searched for eligible studies. Pooled odds ratios (OR) and corresponding 95% confidence intervals (95%CI) were calculated using a fixed- or random-effects model. 11 publications (a total of 2577 cases and 4572 controls) were finally included into this meta-analysis. Meta-analyses indicated that null genotypes of GSTM1/GSTT1 and dual null genotype of GSTM1–GSTT1 were all associated with increased risk of DM (GSTM1: OR _{random-effects} = 1.60, 95%CI 1.10–2.34, P_OR = 0.014; GSTT1: OR _{random-effects} = 1.47, 95%CI 1.12–1.92, P_OR = 0.005; GSTM1–GSTT1: OR _{fixed-effects} = 1.83, 95%CI 1.30–2.59, P_OR = 0.001). Subgroup by ethnicity suggested significant associations between null genotypes of GSTM1 and GSTT1 and DM risk among Asians (GSTM1: OR _{random-effects} = 1.77, 95%CI 1.24–2.53, P_OR = 0.002; GSTT1: OR _{random-effects} = 1.58, 95%CI 1.09–2.27, P_OR = 0.015). This meta-analysis suggests null genotypes of GSTM1/GSTT1 and dual null genotype of GSTM1–GSTT1 are all associated with increased risk of DM, and null genotypes of GSTM1/GSTT1 and dual null genotype of GSTM1–GSTT1 are potential biomarkers of DM.     

Progranulin polymorphism rs5848 is associated with increased risk of Alzheimer's disease

Progranulin is the precursor of granulins, and its down-regulation leads to neurodegeneration. Recent studies have indicated an association of progranulin polymorphism rs5848 with Alzheimer's disease (AD) risk, but the results remain controversial. To verify the association between rs5848 and AD risk, we retrieved the published literature from PubMed and other databases, and performed a meta-analysis by pooling all five studies containing 2502 AD cases and 2162 controls. The results showed that rs5848 is associated with increased risk of AD in homozygous (TT vs. CC: OR, 1.36; 95% CI, 1.11–1.66; P = 0.003) and recessive models (TT vs. CC + CT: OR, 1.31; 95% CI, 1.08–1.58; P = 0.006). This association was remained in Caucasian (2227 cases and 1902 controls). Our data indicate that TT allele of rs5848 is associated with increased risk of AD, suggesting that genetic variant of progranulin gene may play an important role in AD development.     

A common polymorphism in pre-microRNA-146a is associated with lung cancer risk in a Korean population

Introduction

MicroRNAs (miRs) play important roles in the development and progression of human cancers. MiR-146a down-regulates epidermal growth factor receptor and the nuclear factor-κB regulatory kinase interleukin-1 receptor-associated kinase 1 genes that play important roles in lung carcinogenesis. This study was conducted to evaluate the association between rs2910164C>G, a functional polymorphism in the pre-miR-146a, and lung cancer risk.

Material and methods

The rs2910164C>G genotypes were determined in 1094 patients with lung cancer and 1100 healthy controls who were frequency matched for age and gender.

Results

The rs2910164 CG or GG genotype was associated with a significantly decreased risk for lung cancer compared to that of the CC genotype (adjusted odds ratio = 0.80, 95% confidence interval = 0.66–0.96, P = 0.02). When subjects were stratified according to smoking exposure (never, light and heavy smokers), the effect of the rs2910164C>G genotype on lung cancer risk was significant only in never smokers (adjusted odds ratio = 0.66, 95% confidence interval = 0.45–0.96, P = 0.03, under a dominant model for the C allele) and decreased as smoking exposure level increased (P_trend < 0.001). In line with this result, the level of miR-146a expression in the tumor tissues was significantly higher in the GG genotype than in the CC or CG genotype only in never-smokers (P = 0.02).

Conclusions

These findings suggest that the rs2910164C>G in pre-miR-146a may contribute to genetic susceptibility to lung cancer, and that miR-146a might be involved in lung cancer development.     

Single nucleotide polymorphism in hMLH1 promoter and risk of tobacco-related oral carcinoma in high-risk Asian Indians

hMLH1 is a member of mismatch repair genes (MMR) that plays a crucial role in correcting replication errors, cell cycle arrest, apoptosis and oxidative stress. We explored the risk associated with hMLH1 − 93 A>G (rs 1800734) single nucleotide polymorphism (SNP) with the oral squamous cell carcinoma (OSCC) in Asian Indians. We genotyped 242 patients with tobacco-related OSCC and 205 healthy controls by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique. The frequency of AA genotype was found to be significantly (P_c < 0.0006) lower in patients as compared to the controls (21.49% vs. 47.8%) while GG genotype showed significantly higher (P_c < 0.0006) prevalence in patients as compared to the healthy controls (41.32% vs. 13.66%). In logistic regression analysis AG (adjusted OR = 1.95, 95% CI = 0.72–5.26) and GG genotype (adjusted OR = 4.5, 95% CI = 1.54–13.16, P = 0.006) appeared susceptible when compared with the wild-type AA genotype. The allelic distribution showed that variant G allele is significantly higher (P_c < 0.0004) in patients and associated with increased risk (adjusted OR = 2.36, 95% CI = 1.33–4.19, P = 0.003) as compared to the wild-type A allele. Altogether, our results suggest that the hMLH1 − 93 A>G polymorphism is associated with the higher risk of tobacco-related OSCC in Asian Indians and could be useful in screening population at a higher risk.     

Polymorphisms of the TLR4 gene and risk of gastric cancer

Objective

Toll-like receptor 4 (TLR4) is an important lipo-polysaccharide (LPS) receptor in gastric epithelial cell signaling transduction and plays critical roles in the development and progression of gastric cancer (GC). We investigated the effects of TLR4 gene polymorphisms and gene–environmental interactions on the risk of GC in Northeastern China.

Methods

We genotyped two single-nucleotide polymorphisms (SNPs) in TLR4 (rs10116253 and rs1927911) in 217 GC patients and 294 cancer-free controls using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. Odds ratio (OR) and 95% confidence intervals (CIs) were estimated by unconditional logistic-regression models.

Results

Individuals carrying CC genotype of rs10116253 and TT genotype of rs1927911 had a significantly decreased risk of GC (adjusted OR = 0.33, 95% CI 0.18–0.60, P < 0.001 and adjusted OR = 0.37, 95% CI 0.21–0.67, P = 0.001 respectively), compared with TT genotype of rs10116253 and CC genotype of rs1927911. In addition, the SNP effects were additive to the effects of some known environmental factors without any interaction between them in the susceptibility to GC.

Conclusion

Our data suggested that TLR4 gene polymorphisms may be associated with a decreased risk of GC in Chinese population. And these SNPs and their combined effects with environmental factors may be associated with the risk of GC.     

Interleukin (IL)-21 promoter polymorphism increases the risk of thyroid cancer in Chinese population

Polymorphisms in Interleukin (IL)-21 have been researched in several cancers, but the association between IL-21 polymorphisms and thyroid cancer remains unclarified. This case–control study explored the role of five tagSNPs (rs12508721C > T, rs907715G > A, rs13143866G > A, rs2221903A > G and rs4833837A > G) in IL-21 gene in thyroid cancer development. IL-21 genotypes were examined in 615 thyroid cancer patients and 600 controls in Chinese population, and the associations with the risk of thyroid cancer were estimated by logistic regression. Moreover, the potential role of rs12508721C > T in thyroid cancer was further explored by biochemical assays. Compared with the rs12508721CC genotype, CT genotype presented a significantly decreased risk of thyroid cancer (adjusted odds ratios [OR] = 0.72; 95%CI = 0.57–0.94), the TT carriers had a further decreased risk of thyroid cancer (OR = 0.56; 95%CI = 0.41–0.87). Furthermore, our quantitative real-time PCR and Enzyme-linked immunosorbent assay (ELISA) results demonstrated that the presence of rs12508721T allele led to more IL-21 expression. However, no significant difference was found in genotype frequencies for other four sites between cases and controls. These findings suggested that rs12508721 polymorphism in IL-21 might be a genetic modifier for the development of thyroid cancer.     

First evidence for the contribution of the genetic variations of BRCA1-interacting protein 1 (BRIP1) to the genetic susceptibility of cervical cancer

BRIP1 (BRCA1-interacting protein 1), a DNA-dependent ATPase and a DNA helicase, is critical for BRCA-associated DNA damage repair functions, and may be involved in the development of cervical cancer. Genetic markers in different regions of the BRIP1 gene have a plausible role in modulating the risk of cervical cancer. In this study, we evaluate the association between the BRIP1 variations and the risk of cervix cancer. We examined the potential association between cervical cancer and eighteen single nucleotide polymorphisms (SNPs, rs2048718, rs16945692, rs4968451, rs6504074, rs4988344, rs8077088, rs10515211, rs9897121, rs9906313, rs2159450, rs4986764, rs11871785, rs4986763, rs11079454, rs7213430, rs34289250, rs4988345 and rs12937080) of the BRIP1 gene using the MassARRAY system. The participants enrolled in this study included 298 patients with cervical cancer and 286 healthy women as the healthy controls from a Chinese Han population. The results showed that rs16945692 (intron 1), rs4968451 (intron 4), rs4986764 (exon 18) and rs7213430 (3′UTR) were significantly associated with cervical cancer (P < 0.05). Furthermore, strong linkage disequilibrium (LD) was observed in three blocks (D′ > 0.9), and significantly more T–A–C–A haplotypes (block 1) (P = 0.001) were found in the patients with cervical cancer. Significantly higher frequencies of C–A–T haplotypes (block 2) (P = 0.018) and A–A haplotypes (block 3) (P = 0.009) were detected in the healthy controls than in the patients with cervical cancer, suggesting that they may show protective effects against cervical cancer. These findings point to a role for the BRIP1 gene polymorphisms in cervical cancer in a Chinese Han population, and may be informative for future genetic or biological studies on cervical cancer.     

The arachidonate 5-lipoxygenase-activating protein (ALOX5AP) gene SG13S114 polymorphism and ischemic stroke in Chinese population: A meta-analysis

Previous studies have indicated that the arachidonate 5-lipoxygenase-activating protein (ALOX5AP) gene SG13S114 polymorphism is associated with risk of ischemic stroke (IS), but the results remain inconclusive even in Chinese population. A meta-analysis of 10 case-control studies was conducted on the relationship between ALOX5AP SG13S114 polymorphism and susceptibility to IS in Chinese population published domestically and abroad from September 2007 to December 2012. Data were extracted by two authors and pooled odds ratios (ORs) and 95% confidence intervals (CIs) were calculated. Meta-analysis results showed that the significant association between SG13S114 variant and IS was found under the allelic (OR = 0.87, 95% CI: 0.80–0.96, P = 0.004), dominant (OR = 0.75, 95% CI: 0.62–0.92, P = 0.005), and recessive (OR = 0.89, 95% CI: 0.82–0.97, P = 0.005) genetic models in Chinese population. In subgroup meta-analysis, SG13S114 variant and atherothrombotic stroke, rather than lacunar stroke, showed the significant association under the allelic (OR = 0.86, 95% CI: 0.80–0.92, P < 0.0001), dominant (OR = 0.72, 95% CI: 0.57–0.91, P = 0.006), and recessive (OR = 0.86, 95% CI: 0.78–0.95, P = 0.002) models. ALOX5AP SG13S114 polymorphism is associated with susceptibility to IS in Chinese population.     

Meta-analyses of HFE variants in coronary heart disease

Aim

HFE gene variants can cause hereditary hemochromatosis (HH) that often comes along with an increased risk of coronary heart disease (CHD). The goal of our study is to assess the contribution of four HFE gene variants to the risk of CHD.

Methods and results

We conducted four meta-analyses of the studies examining the association between four HFE gene variants and the risk of CHD. A systematic search was conducted using MEDLINE, EMBASE, Web of Science and China National Knowledge Infrastructure (CNKI), Wanfang Chinese Periodical.

Results

Meta-analyses showed that HFE rs1799945-G allele was associated with a 6% increased risk of CHD (P = 0.02, odds ratio (OR) = 1.06, 95% confidence interval (CI) = 1.01–1.11). However, no association between the other three HFE gene variants (rs1800562, rs1800730, and rs9366637) and CHD risk was observed by the meta-analyses (all P values > 0.05). In addition, the results of our case–control study indicated that rs1800562 and rs1800730 were monomorphic, and that rs1799945 and rs9366637 were not associated with CHD in Han Chinese.

Conclusions

Our meta-analysis suggested that a significant association existed between rs1799945 mutation and CHD, although this mutation was rare in Han Chinese.     

Tagging SNPs in the ERCC4 gene are associated with gastric cancer risk

ERCC4 plays an essential role in the nucleotide excision repair (NER) pathway, which is involved in the removal of a wide variety of DNA lesions. To determine whether the ERCC4 tagging SNPs (tSNPs) are associated with risk of gastric cancer, we conducted a hospital-based case-control study of 350 cases and 468 cancer-free controls. In the logistic regression (LR) analysis, we found a significantly decreased risk of gastric cancer associated with the rs744154 GC/CC genotypes [adjusted odds ratio (OR) = 0.56, 95% confidence interval (CI) = 0.42–0.75, false discovery rate (FDR) P = 0.003] compared with the wild-type GG genotype. Haplotype-based association study revealed that the CGC haplotype that containing the rs744154 C allele can decrease the risk of gastric cancer compared with the most common haplotype GGT (adjusted OR = 0.61, 95% CI = 0.46–0.81). Using the multifactor dimensionality reduction (MDR) analysis, we identified that the SNP rs744154 and smoking status were the best two predictive factors for gastric cancer with a testing accuracy of 55.76% and a perfect cross-validation consistency (CVC) of 10 (P = 0.001). Furthermore, the smokers with the rs744154 GC/CC genotypes showed a decreased risk of gastric cancer (adjusted OR = 0.55, 95% CI = 0.35–0.85) compared with the smokers with the GG genotype using multivariate LR analysis. The above findings consistently suggested that genetic variants in the ERCC4 gene may play a protective role in the etiology of gastric cancer, even in the smokers.     

Combined analysis of polymorphism variants in hMTH1, hOGG1 and MUTYH genes on the risk of type 2 diabetes in the Chinese population

Reactive oxygen species are considered to play a role in the development of type 2 diabetes mellitus (T2DM) and its complications. 8-Oxoguanine, which is one of the major oxidation base lesions produced by reactive oxygen species, may cause G:C to T:A transversion mutations because it can mispair with adenine. hMTH1 (human mutT homolog 1), hOGG1 (human 8-oxoguanine glycosylase 1) and MUTYH (human mutY homolog) genes constitute the 8-oxoG repair pathway. In this study, we screened for the polymorphism variants Val83Met (c.247G>A, rs4866) in hMTH1; c.-53G>C (rs56387615), c.-23A>G (rs1801129) and c.-18G>T (rs1801126) in the 5′-UTR of hOGG1; and AluYb8 insertion in MUTYH (AluYb8MUTYH, rs10527342) and investigated their synergistic effect on the risk of T2DM in the Chinese population. The genotypes were determined by electrophoresis, a high-resolution melting technique and sequencing of PCR products. Our results showed that the c.247G>A variant in the hMTH1 gene increased the risk of T2DM in > 55 years of age groups (OR = 1.579; 95%CI: 1.029–2.421). The set of c.-53G>C, c.-23A>G and c.-18G>T variants detected in the 5′-UTR of the hOGG1 gene and the AluYb8 insertion in the MUTYH gene were each associated with an increased risk of T2DM (OR = 1.507, 95%CI: 1.122–2.024; OR = 1.229, 95%CI: 1.030–1.466, respectively). Combined analysis of the variations among the three genes suggested that the c.247G>A variant in hMTH1 combined with AluYb8MUTYH variant had a synergistic effect on increasing the risk of T2DM (OR = 1.635; 95%CI: 1.147–2.330). This synergy was also observed between the variants in the 5′-UTR of the hOGG1 and the AluYb8MUTYH variant (OR = 1.804; 95%CI: 1.254–2.595). Our results suggest, for the first time, the combined effects of AluYb8MUTYH with either hMTH1 c.247G>A or variants in the 5′-UTR of the hOGG1 on the risk of T2DM.     

Association of TLR and TREM-1 gene polymorphisms with risk of coronary artery disease in a Russian population

Atherosclerosis, manifesting itself as acute coronary syndrome, stroke, and peripheral arterial diseases, is a chronic progressive inflammatory disease which is driven by responses of both innate and adaptive immunity. Toll-like receptors (TLRs) and Triggering Receptor Expressed on Myeloid Cells-1 (TREM-1) are important effectors of the innate immune system, and polymorphisms within genes encoding them may increase risk of occurrence of various pathologies including cardiovascular disorders. Thus, we carried out a genetic association study on the sample of 702 consecutive Caucasian (Russian) patients with coronary artery disease (CAD) and 300 age-, sex-, and ethnicity-matched healthy controls. We revealed that the C/C genotype of the TLR1 rs5743551 polymorphism was significantly associated with a reduced risk of CAD according to the recessive model (OR = 0.41, 95% CI = 0.20–0.84, P = 0.017, adjusted by age and gender). Concerning TREM-1 gene polymorphisms, we found that A/A genotype of the rs2234237 polymorphism, the G/G genotype of the rs6910730 polymorphism, the C/C genotype of the rs9471535 polymorphism, and the T/T genotype of the rs4711668 polymorphism were significantly associated with elevated CAD risk according to the recessive model (OR = 5.52, 95% CI = 1.17–25.98, P = 0.011; OR = 4.28, 95% CI = 1.09–16.81, P = 0.021; OR = 5.55, 95% CI = 1.18–26.09, P = 0.011, and OR = 1.66, 95% CI = 1.10–2.52, P = 0.014, respectively, adjusted by age and gender). Conversely, the G allele of the rs1817537 polymorphism, the T allele of the rs2234246 polymorphism, and the T allele of the rs3804277 polymorphism significantly correlated with similarly decreased risk of CAD according to the dominant model (OR = 0.57, 95% CI = 0.40–0.81, P = 0.0013; OR = 0.59, 95% CI = 0.42–0.84, P = 0.003, and OR = 0.58, 95% CI = 0.41–0.81, P = 0.0014, respectively, adjusted by age and gender). We conclude that certain TLR and TREM-1 gene polymorphisms may be associated with CAD in Russian population; however, their significance as predictive and pathogenic markers of CAD should be interpreted with caution in other populations.     

Meta-analysis supports association of a functional SNP (rs1801133) in the MTHFR gene with Parkinson's disease

The MTHFR is a candidate risk gene for Parkinson's disease (PD), and a functional SNP (rs1801133) in the coding region of this gene has been investigated for the associations with the illness extensively among worldwide populations, but overall the results were inconsistent. Here, to assess the relationship between rs1801133 and risk of PD in general populations, we conducted a systematic meta-analysis by combining all available case–control samples in European and Asian populations, with a total of 1820 PD cases and 7530 healthy controls, and the pooled odds ratios (ORs) and 95% confidence intervals (95% CIs) for rs1801133 and PD were calculated using the Mantel–Haenszel method with a fixed-effect model. Overall, rs1801133 was significantly associated with the risk of PD (allelic model, pooled OR = 1.212 for T allele, 95% CI = 1.097–1.340, p-value = 0.0002). When stratifying for ethnicity, significant association was also observed in European (allelic model, pooled OR = 1.187 for T allele, 95% CI = 1.058–1.332, p-value = 0.004) and Asian samples (allelic model, pooled OR = 1.293 for T allele, 95% CI = 1.058–1.580, p-value = 0.012) respectively. In addition, rs1801133 was also significantly associated with MTHFR mRNA expression in both CEU (European, p-value = 0.0149) and CHB (Chinese, p-value = 0.0178) HapMap populations. Collectively, our meta-analysis suggests that rs1801133 is significantly associated with susceptibility to PD in European and Asian populations, and MTHFR is likely an authentic risk gene for PD.     

The genetic polymorphisms of cathepsin S were associated with metabolic disorders in a Chinese Han population

Cathepsin S (CTSS) played an important role in the etiology of cardiovascular disease and metabolic syndrome. Few studies had been reported on the association between the polymorphisms of CTSS and metabolic disorders in Asian population. Therefore we explored the association between the polymorphisms of CTSS and metabolic disorders in a Chinese Han population. The subjects were a Chinese Han cohort with 1160 participants, and the genotyping was performed with PCR-RFLP. Polymorphism rs16827671 was associated with BMI and serum total cholesterol (P = 0.001; P = 0.02, respectively). Subjects with CT genotype of rs16827671 had a higher risk of hypercholesterolemia (OR = 1.64, 95% CI: 1.15–2.33, P = 0.006) compared with TT genotype. Subjects with AG genotype of rs11576175 had lower risks of hypertriglyceridemia and borderline hypercholesterolemia (OR = 0.52, 95% CI: 0.36–0.73, P = 0.0001; OR = 0.52, 95% CI: 0.35–0.77, P = 0.001, respectively) compared with GG genotype. Compared with the haplotype TG, haplotype TA had a lower risk of hypertriglyceridemia and a higher risk of borderline hypercholesterolemia (OR = 0.62, 95% CI: 0.44–0.88, P = 0.002; OR = 1.59, 95% CI: 1.10–2.31, P = 0.008, respectively), and haplotype CA had a lower risk of hypercholesterolemia (OR = 0.35, 95% CI: 0.18–0.68, P = 0.002). In conclusion, we found that the genetic polymorphisms of CTSS were associated with metabolic disorders in a Chinese Han population, which would enrich the knowledge on genetic mechanisms of the pathogenesis of metabolic disorders.     

Association of POL1, MALT1, MC4R, PHLPP and DSEL single nucleotide polymorphisms in chromosome 18q region with type 2 diabetes in Tunisians

Previous studies and replication analyses have linked chromosome 18q21.1–23 with type 2 diabetes (T2DM) and its complications, including diabetic nephropathy (DN). Here we investigated the association of POL1-nearby variant rs488846, MALT1-nearby variant rs2874116, MC4R-nearby variant rs1942872, PHLPP rs9958800 and DSEL-nearby variant rs9966483 single nucleotide polymorphisms (SNPs) in the 18q region, previously linked with DN in African-Americans, with T2DM in (North African) Tunisian subjects, followed by their association with DN, which was performed subsequent to the analysis of the association with T2DM. Study subjects comprised 900 T2DM cases and 748 normoglycemic control, and genotyping was carried out by PCR–RFLP analysis. Of the 5 SNPs analyzed, POL1-nearby variant rs488846 [P = 0.044], and MC4R-nearby variant rs1942872 [P = 0.012] were associated with moderate risk of T2DM. However, there was a lack of consistency in the association of the 5 tested SNPs with DN. As such, it appears that the three chromosome 18q region variants appear to play a role in T2DM pathogenesis, but not with DN in North African Tunisian Arabs.     

XRCC1 polymorphisms and differentiated thyroid carcinoma risk: A meta-analysis

The objective of this study is to quantitatively derive a more precise estimation of the association between X-ray repair cross-complementing group 1 (XRCC1) gene polymorphisms and differentiated thyroid carcinoma risk. A comprehensive literature search of three databases was conducted. Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated with fixed-effect models and random-effect models when appropriate. Overall, no association of the XRCC1 Arg399Gln, Arg280His, and Arg194Trp polymorphisms with differentiated thyroid carcinoma risk was found. In subgroup analyses, a decreased differentiated thyroid carcinoma risk was observed among Caucasians (Gln vs. Arg, OR = 0.86, 95% CI = 0.77–0.96, P = 0.343 for heterogeneity; Gln/Arg vs. Arg/Arg, OR = 0.84, 95% CI = 0.71–0.98, P = 0.229 for heterogeneity; Gln/Gln vs. Arg/Arg, OR = 0.77, 95% CI = 0.60–0.99, P = 0.477 for heterogeneity; dominant genetic model, OR = 0.82, 95% CI = 0.71–0.95, P = 0.272 for heterogeneity), not among Asians. No publication bias was observed. Our results suggest that XRCC1 Arg399Gln polymorphism is not associated with differentiated thyroid carcinoma risk, while a decreased risk is observed among Caucasian population.     

Association of functional FEN1 genetic variants and haplotypes and breast cancer risk

Aim

As a tumor suppressor, FEN1 plays an essential role in preventing tumorigenesis. Two functional germline variants (-69G > A and 4150G > T) in the FEN1 gene have been associated with DNA damage levels in coke-oven workers and multiple cancer risk in general populations. However, it is still unknown how these genetic variants are involved in breast cancer susceptibility.

Methods

We investigated the association between these polymorphisms and breast cancer risk in two independent case–control sets consisted of a total of 1100 breast cancer cases and 1400 controls. The influence of these variations on FEN1 expression was also examined using breast normal tissues.

Results

It was found that the FEN1-69GG genotypes were significantly correlated to increased risk for developing breast cancer compared with the -69AA genotype in both sets [Jinan set: odds ratios (OR) = 1.41, 95% confidence interval (CI) = 1.20–1.65, P = 1.9×10^− 5; Huaian set: OR = 1.51, 95% CI = 1.22–1.86, P = 1.7×10^− 4]. Similar results were observed for 4150G > T polymorphism. The genotype–phenotype correlation analyses demonstrated that the -69G or 4150G allele carriers had more than 2-fold decreased FEN1 expression in breast tissues compared with -69A or 4150T carriers, suggesting that lower FEN1 expression may lead to higher risk for malignant transformation of breast cells.

Conclusion

Our findings highlight FEN1 as an important gene in human breast carcinogenesis and genetic variants in FEN1 confer susceptibility to breast cancer.