Genetic risk score of common genetic variants for impaired fasting glucose and newly diagnosed type 2 diabetes influences oxidative stress

Antioxidant enzyme and DNA base repair genetic risk scores' associations with systemic oxidative stress biomarker in pooled cross-sectional studies

Background: Oxidative stress is hypothesized to contribute to the pathogenesis of several chronic diseases. Numerous dietary and lifestyle factors are associated with oxidative stress; however, little is known about associations of genetic factors, individually or jointly with dietary and lifestyle factors, with oxidative stress in humans. Methods: We genotyped 22 haplotype-tagging single nucleotide polymorphisms (SNPs) in 3 antioxidant enzyme (AE) genes and 79 SNPs in 14 DNA base excision repair (BER) genes to develop oxidative stress-specific AE and BER genetic risk scores (GRS) in two pooled cross-sectional studies (n = 245) of 30-74-year-old, White, cancer- and inflammatory bowel disease-free adults. Of the genotypes, based on their associations with a systemic oxidative stress biomarker, plasma F₂-isoprostanes (FiP) concentrations, we selected 4 GSTP1 SNPs for an AE GRS, and 12 SNPs of 5 genes (XRCC1, TDG, PNKP, MUTYH, and FEN1) for a BER GRS. We also calculated a previously-reported, validated, questionnaire-based, oxidative stress biomarker-weighted oxidative balance score (OBS) comprising 17 anti- and pro-oxidant dietary and lifestyle exposures, with higher scores representing a higher predominance of antioxidant exposures. We used general linear regression to assess adjusted mean FiP concentrations across GRS and OBS tertiles, separately and jointly. Results: The adjusted mean FiP concentrations among those in the highest relative to the lowest oxidative stress-specific AE and BER GRS tertiles were, proportionately, 11.8% (p = 0.12) and 21.2% (p = 0.002) higher, respectively. In the joint AE/BER GRS analysis, the highest estimated mean FiP concentration was among those with jointly high AE/BER GRS. Mean FiP concentrations across OBS tertiles were similar across AE and BER GRS strata. Conclusion: Our pilot study findings suggest that DNA BER, and possibly AE, genotypes collectively may be associated with systemic oxidative stress in humans, and support further research in larger, general populations.

Genetic risk score is associated with T2DM and diabetes complications risks

BACKGROUND

Type 2 diabetes mellitus (T2DM) is a prototypical complex disease with polygenic architecture playing an important role in determining susceptibility to develop the disease (and its complications) in subjects exposed to modifiable lifestyle factors. A current challenge is to quantify the degree of the individual's genetic risk using genetic risk scores (GRS) capturing the results of genome-wide association studies while incorporating possible ethnicity- or population-specific differences.

METHODS

This study included three groups of T2DM (T2DM-I, N=1,032; T2DM-II, N=353; and T2DM-III, N=399) patients and 2,481 diabetes-free subjects. The status of the microvascular and macrovascular diabetes complications were known for the T2DM-I patients. Overall, 21 single nucleotide polymorphisms (SNPs) were analyzed, and selected subsets were used to determine the GRS (both weighted - wGRS and unweighted - uGRS) for T2DM risk predictions (6 SNPs) and for predicting the risks of complications (7 SNPs).

RESULTS

The strongest T2DM markers (P<0.0001) were within the genes for TCF7L2 (transcription factor 7-like 2), FTO (fat mass and obesity associated protein) and ARAP1 (ankyrin repeat and PH domain 1). The T2DM-I subjects with uGRS values greater (Odds Ratio, 95% Confidence Interval) than six had at least twice (2.00, 1.72-2.32) the risk of T2DM development (P<0.0001), and these results were confirmed in the independent groups (T2DM-II 1.82, 1.45-2.27; T2DM-III 2.63, 2.11-3.27). The wGRS (>0.6) further improved (P<0.000001) the risk estimations for all three T2DM groups. The uGRS was also a significant predictor of neuropathy (P<0.0001), nephropathy (P<0.005) and leg ischemia (P<0.0005).

CONCLUSIONS

If carefully selected and specified, GRS, both weighted and unweighted, could be significant predictors of T2DM development, as well as the diabetes complications development.

Joint Exposure to Positive Affect, Life Satisfaction, Depressive Symptoms, and Neuroticism and Incident Type 2 Diabetes

CONTEXT

Whether the psychological wellbeing status could be a risk factor for type 2 diabetes is unclear.

OBJECTIVE

We aimed to measure the association between combined psychological wellbeing factors and type 2 diabetes and investigate whether this association was modified by genetic predisposition.

METHODS

Prospective cohort study from the UK Biobank. In total, 127 496 participants who completed a psychological wellbeing questionnaire and did not have type 2 diabetes at baseline (2006-2010) were included; among them, 88 584 (69.5%) were analyzed to determine their genetic predisposition. The main outcome measure was incident type 2 diabetes.

RESULTS

During the median follow-up of 10.0 years, 2547 incident type 2 diabetes cases were documented. Moderate to extreme unhappiness, satisfaction score ≤3, presence of broad depression, and a neuroticism score ≥3 were all significantly and independently associated with an increased risk of diabetes. When considered as a combination indicator, compared with individuals in the highest quartile of the psychological wellbeing score, the fully adjusted hazard ratios (95% CI) of type 2 diabetes were 1.41 (1.21-1.65) in the third quartile, 1.45 (1.24-1.69) in the second quartile, and 1.73 (1.48-2.01) in the lowest quartile. In the stratified analysis, we observed significant interactions between age and physical activity, and type 2 diabetes (Pinteraction < .001 and 0.049, respectively). However, there was no significant interaction between the psychological wellbeing score and genetic susceptibility to diabetes (Pinteraction = .980).

CONCLUSION

Worse overall psychological wellbeing was associated with a significantly increased risk of type 2 diabetes in a dose-response fashion regardless of genetic predisposition.

Early Prediction for Prediabetes and Type 2 Diabetes Using the Genetic Risk Score and Oxidative Stress Score

We aimed to use a genetic risk score (GRS) constructed with prediabetes and type 2 diabetes-related single nucleotide polymorphisms (SNPs) and an oxidative stress score (OSS) to construct an early-prediction model for prediabetes and type 2 diabetes (T2DM) incidence in a Korean population. The study population included 549 prediabetes and T2DM patients and 1036 normal subjects. The GRS was constructed using six prediabetes and T2DM-related SNPs, and the OSS was composed of three recognized oxidative stress biomarkers. Among the nine SNPs, six showed significant associations with the incidence of prediabetes and T2DM. The GRS was profoundly associated with increased prediabetes and T2DM (OR = 1.946) compared with individual SNPs after adjusting for age, sex, and BMI. Each of the three oxidative stress biomarkers was markedly higher in the prediabetes and T2DM group than in the normal group, and the OSS was significantly associated with increased prediabetes and T2DM (OR = 2.270). When BMI was introduced to the model with the OSS and GRS, the area under the ROC curve improved (from 69.3% to 70.5%). We found that the prediction model composed of the OSS, GRS, and BMI showed a significant prediction ability for the incidence of prediabetes and T2DM.

Quantile-specific heritability of 8-isoprostane and the modulating effects of smoking, alcohol, cardiovascular disease and diabetes on 8-isoprostane-gene interactions

BACKGROUND

Urinary 8-isoprostane provides a significantly heritable measure of oxidative stress. Prior reports suggest that genetic variants may modulate oxidative stress due to smoking, other environmental factors, and disease. Alternatively, these apparent modulations may reflect a dependence of genetic effects on 8-isoprostane concentrations.

METHOD

To test whether genetic effects on 8-isoprostane concentrations are quantile-dependent, quantile-specific offspring-parent (β_OP) and full-sib regression slopes (β_FS) were estimated by applying quantile regression to the age- and sex-adjusted creatinine-standardized urinary 8-isoprostane concentrations of Framingham Heart Study families. Quantile-specific heritabilities were calculated as h² = 2β_OP/(1+r_spouse) and h² = {(1+8r_spouseβ_FS)^0.5-1}/(2r_spouse)).

RESULTS

Spouse 8-isoprostane concentrations were weakly concordant (r_spouse = 0.06). 8-isoprostane heritability (h²±SE) increased significantly with increasing percentiles of its distribution (P_{linear trend} = 0.0009, P_{quadratic trend} = 0.0007, P_{cubic trend} = 0.003) when estimated from β_OP, and when estimated from β_FS (P_{linear trend} = 0.005, P_{quadratic trend} = 0.09, P_{cubic trend} = 0.06). Compared to the 10th percentile, β_OP-estimated h² was over 22-fold greater at the 90th percentile (P_difference = 9.2 × 10^-5), and 5.3-fold greater when estimated from β_FS (P_difference = 0.004). Significantly higher 8-isoprostane heritability in smokers than nonsmokers (0.352 ± 0.147 vs. 0.061 ± 0.036, P_difference = 0.01), and heavier than lighter drinkers (0.449 ± 0.216 vs. 0.078 ± 0.037, P_difference = 0.01) were eliminated when corrected for the higher 8-isoprostane concentrations of the smokers and heavier drinkers.

CONCLUSION

Heritability of oxidative stress as measured by 8-isoprostane is quantile-dependent, which may contribute to the larger reported effects on oxidative stress by UCP2 -866G > A, IL6 -572C > G and LTA 252A > G polymorphisms in smokers than nonsmokers, by the UCP2 -866G > A polymorphism in coronary heart disease patients, by the ESRRG rs1890552 A > G polymorphism in type 2 diabetics, by the CYBA 242C > T polymorphism after exercise training, by the PLIN 11482G > A/14995A > T haplotype before weight loss, and by the CYBA -930A > G and GSTP1 I105V haplotypes in patients with pulmonary edema.

Variation in resistance to oxidative stress in Oregon-(R)R-flare and Canton-S strains of Drosophila melanogaster

All aerobic organisms are susceptible to damage by reactive oxygen species (ROS). ROS-induced damage has been associated with aging and diseases such as metabolic syndrome and cancer. However, not all organisms develop these diseases, nor do they age at the same rate; this is partially due to resistance to oxidative stress, a quantitative trait attributable to the interaction of factors including genetics and environmental. Drosophila melanogaster represents an ideal system to study how genetic variation can affect resistance to oxidative stress. In this work, oxidative stress (total and mitochondrial ROS), antioxidant response, and Cap 'n' collar isoform C and Spineless gene expression, one pesticide resistant (Oregon R(R)-flare) and wild-type (Canton-S) strains of D. melanogaster, were analyzed to test resistance to basal oxidative stress. ROS, catalase, and superoxide dismutase were determined by flow cytometry, and Cap 'n' collar isoform C and Spineless expression by qRT-PCR. The intensity of oxidative stress due to the pro-oxidant zearalenone in both was evaluated by flow cytometry. Data confirm expected differences in oxidative stress between strains that differ in Cyp450s levels. The Oregon (R)R-flare showed greater ROS, total and mitochondrial, compared to Canton-S. Regarding oxidative stress genes expression Cap 'n' collar isoform C and Spineless (Ss), Oregon R(R)-flare strain showed higher expression. In terms of response to zearalenone mycotoxin, Canton-S showed higher ROS concentration. Our data show variation in the resistance to oxidative stress among these strains of D. melanogaster.

A Genetic Risk Score Improves the Prediction of Type 2 Diabetes Mellitus in Mexican Youths but Has Lower Predictive Utility Compared With Non-Genetic Factors

Background

Type 2 diabetes (T2D) is a multifactorial disease caused by a complex interplay between environmental risk factors and genetic predisposition. To date, a total of 10 single nucleotide polymorphism (SNPs) have been associated with pediatric-onset T2D in Mexicans, with a small individual effect size. A genetic risk score (GRS) that combines these SNPs could serve as a predictor of the risk for pediatric-onset T2D.

Objective

To assess the clinical utility of a GRS that combines 10 SNPs to improve risk prediction of pediatric-onset T2D in Mexicans.

Methods

This case-control study included 97 individuals with pediatric-onset T2D and 84 controls below 18 years old without T2D. Information regarding family history of T2D, demographics, perinatal risk factors, anthropometric measurements, biochemical variables, lifestyle, and fitness scores were then obtained. Moreover, 10 single nucleotide polymorphisms (SNPs) previously associated with pediatric-onset T2D in Mexicans were genotyped. The GRS was calculated by summing the 10 risk alleles. Pediatric-onset T2D risk variance was assessed using multivariable logistic regression models and the area under the receiver operating characteristic curve (AUC).

Results

The body mass index Z-score (Z-BMI) [odds ratio (OR) = 1.7; p = 0.009] and maternal history of T2D (OR = 7.1; p < 0.001) were found to be independently associated with pediatric-onset T2D. No association with other clinical risk factors was observed. The GRS also showed a significant association with pediatric-onset T2D (OR = 1.3 per risk allele; p = 0.006). The GRS, clinical risk factors, and GRS plus clinical risk factors had an AUC of 0.66 (95% CI 0.56-0.75), 0.72 (95% CI 0.62-0.81), and 0.78 (95% CI 0.70-0.87), respectively (p < 0.01).

Conclusion

The GRS based on 10 SNPs was associated with pediatric-onset T2D in Mexicans and improved its prediction with modest significance. However, clinical factors, such the Z-BMI and family history of T2D, continue to have the highest predictive utility in this population.

MYLK and PTGS1 Genetic Variations Associated with Osteoporosis and Benign Breast Tumors in Korean Women

Osteoporosis, characterized by reduced bone mass and increased bone fragility, is a disease prevalent in women. Likewise, breast cancer is a multifactorial disease and considered the major cause of mortality in premenopausal and postmenopausal women worldwide. Our data demonstrated the association of the MYLK gene and PTGS1 gene variants with osteoporosis and benign breast tumor risk and the impact of ovariectomy on osteoporosis in Korean women. We performed a genome-wide association study (GWAS) of women with osteoporosis and benign breast tumors. There were 60 single nucleotide polymorphisms (SNPs) and 12 SNPs in the MYLK and PTGS1 genes, associated with benign breast tumors and osteoporosis. Our study showed that women with homozygous MYLK rs12163585 major alleles had an increased risk of osteoporosis following ovariectomy compared to those with minor alleles. Women carrying the minor PTGS1 rs1213265 allele and not treated via ovariectomy carried a higher risk of osteoporosis than those who underwent ovariectomy with a homozygous genotype at the major alleles. Our results suggest that both the MYLK and PTGS1 genes are genetic factors associated with the phenotypes, and these associations appear to be modulated by ovariectomy.

Identification of a TMEM182 rs141764639 polymorphism associated with central obesity by regulating tumor necrosis factor-α in a Korean population

AIMS

To investigate the effect of a single nucleotide polymorphism (SNP) in transmembrane protein 182 (TMEM182) on the risk of having central obesity and the related phenotype.

METHODS

In total, 2141 subjects with central obesity (n = 827) and normal controls (n = 1314) were included. The most strongly associated SNPs were related to waist circumference, and one SNP, rs141764639, was identified in TMEM182 (p = 7.30E-06, q = 0.0326).

RESULTS

The TC genotype was associated with more central obesity; higher levels of blood pressure, glucose-related parameters, and inflammatory markers; abnormal lipid profiles; and smaller LDL particle sizes than the major allele homozygotes in the total population. TNF-α in the TC genotype showed extremely high levels compared to the TT genotype. There were significant interactions between the genotypes and waist circumference in relation to LDL particle size, TNF-α level, and IL-6 level. Compared with the reference group, the odds ratio for central obesity in C allele carriers was significantly increased by 2-fold.

CONCLUSIONS

The polymorphism of TMEM182 rs141764639 might have an effect on the incidence of central obesity in the Korean population by interacting with the upregulation of TNF-α, a proinflammatory cytokine. Moreover, LDL particle size, which is an atherogenic lipid profile trait, was associated with the TMEM182 rs141764639 genotype.

Genome-wide association study of metabolic syndrome in Korean populations

Metabolic syndrome (MetS) which is caused by obesity and insulin resistance, is well known for its predictive capability for the risk of type 2 diabetes mellitus and cardiovascular disease. The development of MetS is associated with multiple genetic factors, environmental factors and lifestyle. We performed a genome-wide association study to identify single-nucleotide polymorphism (SNP) related to MetS in large Korean population based samples of 1,362 subjects with MetS and 6,061 controls using the Axiom^® Korean Biobank Array 1.0. We replicated the data in another sample including 502 subjects with MetS and 1,751 controls. After adjusting for age and sex, rs662799 located in the APOA5 gene were significantly associated with MetS. 15 SNPs in GCKR, C2orf16, APOA5, ZPR1, and BUD13 were associated with high triglyceride (TG). 14 SNPs in APOA5, ALDH1A2, LIPC, HERPUD1, and CETP, and 2 SNPs in MTNR1B were associated with low high density lipoprotein cholesterol (HDL-C) and high fasting blood glucose respectively. Among these SNPs, 6 TG SNPs: rs1260326, rs1260333, rs1919127, rs964184, rs2075295 and rs1558861 and 11 HDL-C SNPs: rs4775041, rs10468017, rs1800588, rs72786786, rs173539, rs247616, rs247617, rs3764261, rs4783961, rs708272, and rs7499892 were first discovered in Koreans. Additional research is needed to confirm these 17 novel SNPs in Korean population.

Thai CV risk score and primary prevention in impaired fasting plasma glucose or diabetes mellitus versus normoglycemia in patients with metabolic syndrome

Background:

Impaired fasting plasma glucose (IFG) as well as diabetes mellitus (DM) may influence the presence of another metabolic syndrome (MetS) components resulting in the different risk of cardiovascular (CV) morbidity and mortality. This study aimed to determine the impact of IFG as well as DM on the 10-year CV risk using Thai CV risk score and primary prevention in complying with CV risk score in these patients.

Methods:

This cross-sectional study was conducted at the internal medicine clinic, Pathum Thani Hospital, Thailand. The study was approved by the hospital ethics committee and written informed consent was obtained from all patients. Patients having MetS according to the criteria of the International Diabetes Federation were enrolled while those with a history of CVD were excluded. The 10-year CV risk was assessed using the Thai CV risk score.

Results:

The total of 112 patients were enrolled in the study. They were in old age and female sex was a significantly higher proportion (61.70% vs 35.50%, P = 0.013). Of these, 72.32% had IFG or DM. Proportions of patients with moderate and high CV risk score were significantly greater in IFG/DM group and only 34.48% and 79.31% of patients with moderate or high CV risk score received aspirin and statin. IFG or DM significantly elevated CV risk score (OR = 6.66, 95% CI = 2.29, 19.58).

Conclusions:

IFG/DM significantly elevated CV risk score in these patients with the strongest impact. The assessment of CV risk is highly recommended for primary prevention and long-term CVD benefit.