scholarly journals Sex-Specific Genetically Predicted Iron Status in relation to 12 Vascular Diseases: A Mendelian Randomization Study in the UK Biobank

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Fangkun Yang ◽  
Qinyi Bao ◽  
Zhuo Wang ◽  
Menghuai Ma ◽  
Jinlian Shen ◽  
...  
Keyword(s):  
Coronary Atherosclerosis ◽  
Serum Iron ◽  
Mendelian Randomization ◽  
Iron Status ◽  
Transferrin Saturation ◽  
Vascular Diseases ◽  
Lower Extremities ◽  
Vascular Pathology ◽  
Uk Biobank ◽  
The Uk

Background. Iron overload has been implicated in the pathogenesis of varicose veins (VVs). However, the association of serum iron status with other vascular diseases (VDs) is not well understood, which might be a potential target for VD prevention. This study was aimed at investigating the causal associations between iron status and VDs using the Mendelian randomization (MR) method. Methods. A two-sample MR was designed to investigate whether iron status was associated with VDs, based on iron data from a published genome-wide association study meta-analysis of 48,972 subjects of European descent and VD data obtained from the UK Biobank, including 361,194 British subjects (167,020 males and 194,174 females). We further explored whether there was sex difference in the associations between genetically predicted iron status and VDs. Results. The results demonstrated that iron status had a significant causal effect on VVs of lower extremities ( P < 0.001 ) and a potential effect on coronary atherosclerosis ( P < 0.05 for serum iron, ferritin, and transferrin saturation, respectively), but not on other VDs. Furthermore, higher iron status exerted a detrimental effect on VVs of lower extremities in both genders ( P < 0.05 ) and a protective effect on male patients with coronary atherosclerosis ( P < 0.05 for serum iron, ferritin, and transferrin saturation, respectively). Conclusions. This MR study provides robust evidence that higher iron status increases the risk of VVs of lower extremities, whereas it reduces the incidence of coronary atherosclerosis in the male population, which indicates that iron has divergent effects on vascular pathology.

scholarly journals Iron Status and Cancer Risk in UK Biobank: A Two-Sample Mendelian Randomization Study

Nutrients ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 526 ◽  
Author(s):  
Shuai Yuan ◽  
Paul Carter ◽  
Mathew Vithayathil ◽  
Siddhartha Kar ◽  
Edward Giovannucci ◽  
...  
Keyword(s):  
Liver Cancer ◽  
Brain Cancer ◽  
Genome Wide Association Study ◽  
Mendelian Randomization ◽  
Iron Status ◽  
Transferrin Saturation ◽  
Nucleotide Polymorphisms ◽  
Uk Biobank ◽  
Odds Ratios ◽  
A Genome

We conducted a two-sample Mendelian randomization study to explore the associations of iron status with overall cancer and 22 site-specific cancers. Single-nucleotide polymorphisms for iron status were obtained from a genome-wide association study of 48,972 European-descent individuals. Summary-level data for breast and other cancers were obtained from the Breast Cancer Association Consortium and UK Biobank. Genetically predicted iron status was positively associated with liver cancer and inversely associated with brain cancer but not associated with overall cancer or the other 20 studied cancer sites at p < 0.05. The odds ratios of liver cancer were 2.45 (95% CI, 0.81, 7.45; p = 0.11), 2.11 (1.16, 3.83; p = 0.02), 10.89 (2.44, 48.59; p = 0.002) and 0.30 (0.17, 0.53; p = 2 × 10−5) for one standard deviation increment of serum iron, transferrin saturation, ferritin and transferrin levels, respectively. For brain cancer, the corresponding odds ratios were 0.69 (0.48, 1.00; p = 0.05), 0.75 (0.59, 0.97; p = 0.03), 0.41 (0.20, 0.88; p = 0.02) and 1.49 (1.04, 2.14; p = 0.03). Genetically high iron status was positively associated with liver cancer and inversely associated with brain cancer.

P6231Iron status and risk of cardio-metabolic diseases in European adults: a Mendelian randomization study

2019 ◽  
Vol 40 (Supplement_1) ◽  
Author(s):  
W Gan ◽  
D Bennett ◽  
A Mahajan ◽  
H Du ◽  
Z Chen ◽  
...  
Keyword(s):  
Serum Iron ◽  
Metabolic Diseases ◽  
Mendelian Randomization ◽  
Iron Status ◽  
Transferrin Saturation ◽  
Sensitivity Analyses ◽  
European Ancestry ◽  
Research Centre ◽  
Inverse Association ◽  
Total N

Abstract Background Observational studies have reported conflicting results about the associations of iron status with risk of cardio-metabolic diseases but such studies are constrained by confounding and reverse causality. Purpose To assess the causal relevance of iron status biomarkers (transferrin, serum iron, and ferritin) for risk of coronary artery diseases (CAD), ischaemic stroke (IS), and type 2 diabetes (T2D), using Mendelian randomization (MR). Methods Effect size estimates for genetic variants associated with iron status biomarkers were obtained from the Genetics of Iron Status consortium (transferrin saturation, serum iron, and ferritin: n=48,972). The corresponding effects of these variants on the risk of CAD, IS and T2D were obtained from a meta-analysis of unrelated participants of European ancestry in the UK Biobank (UKB), together with previously recruited participants in CARDIOGRAMplusC4D (total n=90,377 CAD cases), MEGASTROKE (total n=43,381 IS cases) and DIAGRAM (total n=74,124 T2D cases), respectively. The main analysis used a two-sample inverse-variance weighted MR, while the sensitivity analyses used weighted-median, weighted-mode, MR-PRESSO, and MR-Egger approaches. Results MR analysis demonstrated significant inverse association of each of the three genetically-instrumented iron status biomarker with risk of CAD (transferrin saturation OR=0.96 [95% CI: 0.92–0.99], p=0.02; serum iron OR=0.93 [0.89–0.97], p=0.001; and ferritin OR=0.86 (0.79–0.94), p=0.001, per 1 SD higher level). In contrast, these iron status biomarkers showed positive associations with risk of T2D (transferrin saturation OR=1.06 [1.01–1.11], p=0.01; serum iron OR=1.06 [0.99–1.13], p=0.07; and ferritin OR=1.12 [0.99–1.26], p=0.06, per 1 SD higher level). There was positive, but non-significant, association of IS with each of the iron status biomarker analysed. Sensitivity analyses using several different MR approaches yielded concordant results. Conclusions Among European adults, iron status appeared to have causal associations, but in opposite directions, with the risk of CHD and T2D. Our findings highlight the need for caution about strategies for advocating iron supplementation in individuals with normal haemoglobin levels for prevention of CAD. Acknowledgement/Funding British Heart Found, Medical Research Council, Wellcome Trust, NIHR Biomedical Research Centre, Oxford

scholarly journals Causal Effects of Genetically Predicted Iron Status on Sepsis: A Two-Sample Bidirectional Mendelian Randomization Study

2021 ◽  
Vol 8 ◽  
Author(s):  
Yuanlong Hu ◽  
Xiaomeng Cheng ◽  
Huaiyu Mao ◽  
Xianhai Chen ◽  
Yue Cui ◽  
...  
Keyword(s):  
Fixed Effects ◽  
Serum Iron ◽  
Mendelian Randomization ◽  
Causal Effect ◽  
Iron Status ◽  
Transferrin Saturation ◽  
Reverse Causality ◽  
Clinical Value ◽  
Causal Direction ◽  
Increased Risk

Background/Aim: Several observational studies showed a significant association between elevated iron status biomarkers levels and sepsis with the unclear direction of causality. A two-sample bidirectional mendelian randomization (MR) study was designed to identify the causal direction between seven iron status traits and sepsis.Methods: Seven iron status traits were studied, including serum iron, ferritin, transferrin saturation, transferrin, hemoglobin, erythrocyte count, and reticulocyte count. MR analysis was first performed to estimate the causal effect of iron status on the risk of sepsis and then performed in the opposite direction. The multiplicative random-effects and fixed-effects inverse-variance weighted, weighted median-based method and MR-Egger were applied. MR-Egger regression, MR pleiotropy residual sum and outlier (MR-PRESSO), and Cochran's Q statistic methods were used to assess heterogeneity and pleiotropy.Results: Genetically predicted high levels of serum iron (OR = 1.21, 95%CI = 1.13–1.29, p = 3.16 × 10−4), ferritin (OR = 1.32, 95%CI = 1.07–1.62, p =0.009) and transferrin saturation (OR = 1.14, 95%CI = 1.06–1.23, p = 5.43 × 10−4) were associated with an increased risk of sepsis. No significant causal relationships between sepsis and other four iron status biomarkers were observed.Conclusions: This present bidirectional MR analysis suggested the causal association of the high iron status with sepsis susceptibility, while the reverse causality hypothesis did not hold. The levels of transferrin, hemoglobin, erythrocytes, and reticulocytes were not significantly associated with sepsis. Further studies will be required to confirm the potential clinical value of such a prevention and treatment strategy.

scholarly journals Iron Status and Risk of Stroke

Stroke ◽  
2018 ◽  
Vol 49 (12) ◽  
pp. 2815-2821 ◽  
Author(s):  
Dipender Gill ◽  
Grace Monori ◽  
Ioanna Tzoulaki ◽  
Abbas Dehghan
Keyword(s):  
Genetic Variants ◽  
Serum Iron ◽  
Detrimental Effect ◽  
Stroke Risk ◽  
Mendelian Randomization ◽  
Iron Status ◽  
Transferrin Saturation ◽  
Cardioembolic Stroke ◽  
Sensitivity Analyses ◽  
Ratio Method

Background and Purpose— Both iron deficiency and excess have been associated with stroke risk in observational studies. However, such associations may be attributable to confounding from environmental factors. This study uses the Mendelian randomization technique to overcome these limitations by investigating the association between genetic variants related to iron status and stroke risk. Methods— A study of 48 972 subjects performed by the Genetics of Iron Status consortium identified genetic variants with concordant relations to 4 biomarkers of iron status (serum iron, transferrin saturation, ferritin, and transferrin) that supported their use as instruments for overall iron status. Genetic estimates from the MEGASTROKE consortium were used to investigate the association between the same genetic variants and stroke risk. The 2-sample ratio method Mendelian randomization approach was used for the main analysis, with the MR-Egger and weighted median techniques used in sensitivity analyses. Results— The main results, reported as odds ratio (OR) of stroke per SD unit increase in genetically determined iron status biomarker, showed a detrimental effect of increased iron status on stroke risk (serum iron OR, 1.07; 95% CI, 1.01–1.14; [log-transformed] ferritin OR, 1.18; 95% CI, 1.02–1.36; and transferrin saturation OR, 1.06; 95% CI, 1.01–1.11). A higher transferrin, indicative of lower iron status, was also associated with decreased stroke risk (OR, 0.92; 95% CI, 0.86–0.99). Examining ischemic stroke subtypes, we found the detrimental effect of iron status to be driven by cardioembolic stroke. These results were supported in statistical sensitivity analyses more robust to the inclusion of pleiotropic variants. Conclusions— This study provides Mendelian randomization evidence that higher iron status is associated with increased stroke risk and, in particular, cardioembolic stroke. Further work is required to investigate the underlying mechanism and whether this can be targeted in preventative strategies.

scholarly journals Coffee Consumption and Cardiovascular Diseases: A Mendelian Randomization Study

Nutrients ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 2218
Author(s):  
Shuai Yuan ◽  
Paul Carter ◽  
Amy M. Mason ◽  
Stephen Burgess ◽  
Susanna C. Larsson
Keyword(s):  
Cardiovascular Disease ◽  
Cardiovascular Diseases ◽  
Intracerebral Hemorrhage ◽  
Genetic Variants ◽  
Odds Ratio ◽  
Observational Studies ◽  
Mendelian Randomization ◽  
Coffee Consumption ◽  
Uk Biobank ◽  
The Uk

Coffee consumption has been linked to a lower risk of cardiovascular disease in observational studies, but whether the associations are causal is not known. We conducted a Mendelian randomization investigation to assess the potential causal role of coffee consumption in cardiovascular disease. Twelve independent genetic variants were used to proxy coffee consumption. Summary-level data for the relations between the 12 genetic variants and cardiovascular diseases were taken from the UK Biobank with up to 35,979 cases and the FinnGen consortium with up to 17,325 cases. Genetic predisposition to higher coffee consumption was not associated with any of the 15 studied cardiovascular outcomes in univariable MR analysis. The odds ratio per 50% increase in genetically predicted coffee consumption ranged from 0.97 (95% confidence interval (CI), 0.63, 1.50) for intracerebral hemorrhage to 1.26 (95% CI, 1.00, 1.58) for deep vein thrombosis in the UK Biobank and from 0.86 (95% CI, 0.50, 1.49) for subarachnoid hemorrhage to 1.34 (95% CI, 0.81, 2.22) for intracerebral hemorrhage in FinnGen. The null findings remained in multivariable Mendelian randomization analyses adjusted for genetically predicted body mass index and smoking initiation, except for a suggestive positive association for intracerebral hemorrhage (odds ratio 1.91; 95% CI, 1.03, 3.54) in FinnGen. This Mendelian randomization study showed limited evidence that coffee consumption affects the risk of developing cardiovascular disease, suggesting that previous observational studies may have been confounded.

Causal Association Between Atopic Dermatitis and Inflammatory Bowel Disease: A 2-Sample Bidirectional Mendelian Randomization Study

2021 ◽  
Author(s):  
Christa Meisinger ◽  
Dennis Freuer
Keyword(s):  
Inflammatory Bowel Disease ◽  
Atopic Dermatitis ◽  
Bowel Disease ◽  
Genome Wide Association Study ◽  
Mendelian Randomization ◽  
Causal Effect ◽  
The Other ◽  
Uk Biobank ◽  
Inflammatory Bowel ◽  
The Uk

Abstract Background Observational studies postulated an association between atopic dermatitis (AD) and inflammatory bowel disease (IBD). However, it remains unclear whether this relationship is causal. Methods To determine whether AD is causally related to IBD and vice versa, a 2-sample Mendelian randomization study was conducted. Independent genetic instruments from the largest available genome-wide association study for AD (EAGLE eczema consortium without the 23andMe study including 10,788 cases and 30,047 controls) were used to investigate the association with IBD in the UK Biobank study (7045 cases, 456,327 controls) and a second European IBD sample (12,882 cases, 21,770 controls). Results Atopic dermatitis was strongly associated with higher risk of IBD as a whole (odds ratio [OR], 1.107; 95% confidence interval [CI], 1.035; 1.183; P = .003) in the UK Biobank study. The positive association was not significant in the other IBD study (OR, 1.114; 95% CI, 0.956; 1.298), but in meta-analyses of results from the 2 studies, the strong association could be confirmed (OR, 1.11; 95% CI, 1.04; 1.18). When evaluating the causal relationship in the other direction, IBD as a whole did not show an association with AD. Subtype analyses revealed that AD was suggestively associated with ulcerative colitis (UC; OR, 1.149; 95% CI, 1.018; 1.297) but not Crohn’s disease (CD). However, there was a suggestive association between CD and AD (OR, 1.034; 95% CI, 1.004; 1.064) but not UC and AD. Conclusions This study supports a causal effect between AD and IBD—but not between IBD and AD. There seems to be considerable differences between UC and CD regarding their specific associations with AD. These findings have implications for the management of IBD and AD in clinical practice.

Abstract P147: Genome Wide Assessment of Shared Genetic Architecture Between Rheumatoid Arthritis and Cardiovascular Diseases Using the UK Biobank Data

Circulation ◽  
2020 ◽  
Vol 141 (Suppl_1) ◽  
Author(s):  
Yanjun Guo ◽  
Wonil Chung ◽  
Zhilei Shan ◽  
Liming Liang
Keyword(s):  
Cardiovascular Diseases ◽  
Genetic Correlation ◽  
Multiple Testing ◽  
Mendelian Randomization ◽  
Meta Analysis ◽  
Uk Biobank ◽  
Increased Risk ◽  
The Uk ◽  
Cardiovascular Traits ◽  
Shared Genetic

Background: Patients with RA have a 2-10 folds increased risk of cardiovascular diseases (CVD) and CVD accounts for almost 50% of the excess mortality in patients with RA when compared with general population, but the mechanisms underlying such associations are largely unknown. Methods: We examined the genetic correlation, causality, and shared genetic variants between RA (Ncase=6,756, Ncontrol=452,476) and CVD (Ncase=44,246, Ncontrol=414,986) using LD Score regression (LDSC), generalized summary-data-based Mendelian Randomization (GSMR), and cross-trait meta-analysis in the UK Biobank Data. Results: In the present study, RA was significantly genetically correlated with MI, angina, CHD, and CVD after correcting for multiple testing (Rg ranges from 0.40 to 0.43, P<0.05/5). Interestingly, when stratified by frequent usage of aspirin and paracetamol, we observed increased genetic correlation between RA and CVD for participants without aspirin usage ( Rg increased to 0.54 [95%CI: 0.54, 0.78] for angina; P value=6.69х10 -6 ), and for participants with usage of paracetamol ( Rg increased to 0.75 [95%CI: 0.20, 1.29] for MI; P value=8.90х10 -3 ). Cross-trait meta-analysis identified 9 independent loci that were shared between RA and at least one of the genetically correlated CVD traits including PTPN22 at chr1p13.2 , BCL2L11 at chr2q13 , and CCR3 at chr3p21.31 ( P single trait <1х10 -3 and P meta <5х10 -8 ) highlighting potential shared etiology between them which include accelerating atherosclerosis and upregulating oxidative stress and vascular permeability. Finally, Mendelian randomization analyses observed inconsistent instrumental effects and were unable to conclude the causality and directionality between RA and CVD. Conclusion: Our results supported positive genetic correlation between RA and multiple cardiovascular traits, and frequent usage of aspirin and paracetamol may modify their associations, but instrumental analyses were unable to conclude the causality and directionality between them.

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