International journal of molecular epidemiology and genetics最新文献

The leptin gene (LEP) plays a regulatory role in satiety, inflammation, and allergy. Prior findings linking leptin to asthma motivated us to investigate whether DNA methylation (DNA-M) of CpG (cytosine-phosphate-guanine) sites in concert with single nucleotide polymorphisms (SNPs) of LEP can explain the risk of asthma and lung function. Methylation of CpG sites was assessed using the Illumina Infinium Human Methylation 450 beadchip in blood samples collected from 10- and 18-year-old boys and girls from the Isle of Wight (IOW) birth cohort (UK). Four LEP SNPs were genotyped. Linear and log linear models were used for the analysis, adjusting for false discovery rate (FDR). The analyses were repeated in the BAMSE cohort (Sweden). In the IOW study, the interaction of cg00666422 and rs11763517 (CT vs TT and CC) was associated with FEV1 (FDR-adjusted p-value: 0.03), FEV1/FVC ratio (FDR-adjusted p-value: 0.0096), and FEF25-75% (FDR-adjusted p-value: 0.00048) such that they decreased with increasing DNA-M. The interaction of the same CpG-SNP pair was also associated with increased risk of asthma at age 18. We replicated the findings for FEV1/FVC and FEF25-75% in a smaller sample of 34 participants at age 10. Regarding the BAMSE cohort, although, the interaction of cg00666422 and rs11763517 on lung function were not significant, the direction of the effect was the same as in IOW cohort. Thus, penetrance of LEP genotype seems to be modified by methylation at cg00666422 and is linked to airway obstruction and asthma.

Background: A gene signature associated with chemo-response in ovarian cancer was created through integration of biological data in The Cancer Genome Atlas (TCGA) and validated in five independent microarray experiments. Our study aimed to determine if single nucleotide polymorphisms (SNPs) within the 422-gene signature were associated with a genetic predisposition to platinum-based chemotherapy response in serous ovarian cancer.

Methods: An association analysis between SNPs within the 422-gene signature and chemo-response in serous ovarian cancer was performed under the log-additive genetic model using the 'SNPassoc' package within the R environment (p<0.0001). Subsequent validation of statistically significant SNPs was done in the Ovarian Cancer Association Consortium (OCAC) database.

Results: 19 SNPs were found to be associated with chemo-response with statistical significance. None of the SNPs found significant in TCGA were validated within OCAC for the outcome of interest, chemo-response.

Conclusions: SNPs associated with chemo-response in ovarian cancer within TGCA database were not validated in a larger database of patients and controls from OCAC. New strategies integrating somatic and germline information may help to characterize genetic predictors for treatment response in ovarian cancer.

The genetic architecture of placental abruption (PA) remains poorly understood. We examined variations in SNPs of circadian clock-related genes in placenta with PA risk. We also explored placental and maternal genomic contributions to PA risk. Placental genomic DNA samples were isolated from 280 PA cases and 244 controls. Genotyping was performed using the Illumina Cardio-MetaboChip. We examined 116 SNPs in 13 genes known to moderate circadian rhythms. Logistic regression models were fit to estimate odds ratios (ORs). The combined effect of multiple SNPs on PA risk was estimated using a weighted genetic risk score. We examined independent and joint associations of wGRS derived from placental and maternal genomes with PA. Seven SNPs in five genes (ARNTL2, CRY2, DEC1, PER3 and RORA), in the placental genome, were associated with PA risk. Each copy of the minor allele (G) of a SNP in the RORA gene (rs2899663) was associated with a 30% reduced odds of PA (95% CI 0.52-0.95). The odds of PA increased with increasing placental-wGRS (Ptrend<0.001). The ORs were 1.00, 2.16, 3.24 and 4.48 across quartiles. Associations persisted after the maternal-wGRS was included in the model. There was evidence of an additive contribution of placental and maternal genetic contributions to PA risk. Participants with placental- and maternal-wGRS in the highest quartile, compared with those in the lowest quartile, had a 15.57-fold (95% CI 3.34-72.60) increased odds of PA. Placental variants in circadian clock-related genes are associated with PA risk; and the association persists after control of genetic variants in the maternal genome.

Background: Host genetic factors may a play role in susceptibility to infection. Vitamin-D is an immunomodulator that may play a role in HIV infection. Vitamin-D action is mediated by the vitamin-D receptor. We establish prevalence of ApaI, BsmI, FokI and TaqI polymorphisms (VDRPs) amongst a black southern African HIV+ve population and investigate polymorphic differences between HIV+ve and -ve people.

Methods: Seventy-nine sex and age-group matched HIV+ve patients of African origin initiating antiretroviral therapy (ART) and 79 HIV-ve participants, also of African origin, were recruited from a public sector HIV testing and treatment clinic and investigated for the 4 polymorphisms. The genotype frequencies were compared, odds ratios and 95% confidence intervals of the association of HIV status and each genotype were calculated. Both dominant, co-dominant, recessive and allele models were tested.

Results: We found no evidence of difference in distribution and association between HIV infection and the genotypes of the BsmI, FokI and TaqI VDR polymorphisms. The genotype distributions were consistent with Hardy-Weinberg equilibrium for these genotypes. The ApaI genotype showed differences in distribution by HIV status in the dominant and co-dominant models. However this finding is cautiously stated as the ApaI genotype violated the Hardy-Weinberg equilibrium and frequency of the minor variant was unexpectedly low in this population.

Conclusion: We do not show convincing differences in distribution of the VDR genotypes among HIV+ve and HIV-ve black southern African persons. Future studies need to be replicated in larger study populations as understanding polymorphic differences and similarities may offer insights into the different susceptibility and progression of HIV in southern African populations.

Telomere length (TL) is a potential biomarker of aging and age-related disease risk. We recently published a novel Luminex-based method for high-throughput, low-cost TL measurement. Here we describe a blinded comparison of the Luminex method to Southern blot, the most precise TL measurement method. Luminex and Southern blot measurements for the same 50 DNA samples were taken in two independent laboratories; each sample was measured twice, several months apart. The inter-assay CV for Luminex ranged from 5.5 to 9.1 (depending on CV estimation method), and Southern blot CV from 1.0 to 1.7. Both measures were inversely associated with age. The correlation between the repeated measurements was 0.66 for Luminex and 0.97 for Southern blot. The correlation between Southern blot and Luminex was 0.65 in round 1 and 0.75 in round 2, and the relationship showed no evidence of non-linearity. Our results demonstrate that the Luminex assay is a valid and reproducible method for high-throughput TL measurement. The Luminex assay involves no DNA amplification, which may make Luminex an attractive alternative to PCR-based TL measurement.

Human RAD17, a human homolog of the Schizosaccharomyces pombe cell cycle checkpoint gene RAD17, plays a significant role in activating checkpoint signals in response to DNA damage. We evaluated the association of hRAD17 Leu546Arg (rs1045051), a missense single nucleotide polymorphism, with the risk of esophageal squamous cell carcinoma in relation to smoking and alcohol consumption history in 154 esophageal squamous cell carcinoma male patients and 695 cancer-free male controls by a case-control study conducted in Japan. The results showed that the hRAD17 Arg/Arg genotype compared to the Leu/Leu and Leu/Arg genotypes was significantly associated with the risk of the esophageal squamous cell carcinoma with an adjusted odds ratios of 2.22 (95% CI: 1.19-4.16 P=0.013). In stratified studies, the risk of esophageal squamous cell carcinoma was markedly higher in light drinkers (less than 23 g ethanol/day) with the Arg/Arg genotype than in heavy drinkers (excess of 23 g ethanol/day) with the Arg/Arg genotype (OR=2.83, 95% CI: 1.05-7.61, P=0.04). We concluded that the genetic variant of hRAD17 Leu546Arg polymorphism exerts a significant effect on esophageal squamous cell carcinoma risk among Japanese men.

Obesity in adolescents has been associated with increased cardiovascular risk factors such as dyslipidemia and insulin resistance. Several factors have been proposed to be associated with cardiovascular risk factors in adolescents including dietary habit, physical activity and genetic. This study was aimed to evaluate the interaction between genetic variation and dietary intake on cardiovascular metabolic risk factors in obese and normal weight adolescents. The UCP2 gene was chosen because it was previously correlated with dietary intake and cardiovascular risk factors. This study is a case control study done in 10 senior high school in Yogyakarta. Subjects were obese and normal weight adolescents taken from an obesity screening with age ranged between 16 and 18 years old. Dyslipidemia was observed by measuring total cholesterol, triglyceride, LDL dan HDL level while insulin resistance was determined by calculating fasting glucose and insulin level. Lipid profile, glucose and insulin level were measured after 8 hours of fasting. UCP2 -866G/A gene polymorphism were determined using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The results show that obese adolescents had significantly higher blood pressure, total cholesterol, LDL, triglyceride, insulin level and lower HDL level than their normal weight counterparts (all p<0.001). In obese adolescents, UCP2 -866G/A was associated with blood pressure (p=0.025), total cholesterol level (p=0.025), LDL (p=0.024) level and HOMA IR (p<0.001) but not with dietary fat intake (p=0.386). Additionally, subjects with UCP2 -866G/A gene polymorphism and high dietary fat intake had lower risk on obesity compared to those without UCP2 -866G/A gene polymorphism and low dietary fat intake. We conclude that the UCP2 -866G/A was associated with dyslipidemia, insulin resistance in obese adolescents. Additionally, we also observed the interaction between UCP2 -866G/A gene polymorphism and dietary intake on the risk of obesity.

Mutations of the gene GNAS have been shown to activate the adenylate cyclase gene and lead to constitutive cAMP signaling. Several preliminary reports have suggested a role for GNAS gene mutations during colorectal carcinogenesis, particularly mucinous carcinomas. The aim of this study was to clarify the incidence of GNAS mutations in adenomas (tubular, tubulovillous, and villous), carcinomas with residual adenoma, and carcinomas, and to relate these findings to mutations of the KRAS gene and to the mucinous status of the tumors. We used standard PCR techniques and direct gene sequencing to evaluate tumors for gene mutations. No GNAS mutations were identified in 25 tubular adenomas, but were present in 6.4% of tubulovillous adenomas and 11.2% of villous adenomas. A GNAS mutation was found in 9.7% of the benign portion of carcinoma with residual adenoma, but in none of 86 carcinomas. A similar trend was seen for KRAS mutation across the five groups of tumors. GNAS mutations may function as an important driver mutation during certain phases of colorectal carcinogenesis, but may then be lost once the biological advantage gained by the mutated gene is no longer necessary to sustain or advance tumor development.

Substantial uncertainty exists as to whether combining multiple disease-associated single nucleotide polymorphisms (SNPs) into a genotype risk score (GRS) can improve the ability to predict the risk of disease in a clinically relevant way. We calculated the ability of a simple count GRS to predict the risk of a dichotomous outcome under both multiplicative and additive models of combined effects. We then compared the results of these simulations with the observed results of published GRS measured within multiple epidemiologic cohorts. If the combined effect of each disease-associated SNP included in a GRS is multiplicative on the risk scale, then a count GRS score should be useful for risk prediction with as few as 10-20 SNPs. Adding additional SNPs to the GRS under this model dramatically improves risk prediction. By contrast, if the combined effect of each SNP included in a GRS is linearly additive on the risk scale, a simple count GRS is unlikely to provide clinically useful risk prediction. Adding additional SNPs to the GRS under this model does not improve risk prediction. The combined effect of SNPs included in several published GRS measured in several well-phenotyped epidemiologic cohort studies appears to be more consistent with a linearly additive effect. A simple count GRS is unlikely to be clinically useful for predicting the risk of a dichotomous outcome. Alternative methods for constructing GRS that attempt to identify and include SNPs that demonstrate multiplicative gene-gene or gene-environment interactive effects are needed.