Ankylosing spondylitis and glaucoma in European population: A Mendelian randomization study

Causal Effect of Fatty Fish Consumption on Influenza: Evidence From Two-Sample Mendelian Randomization

Background

Influenza continues to pose a significant public health threat, with substantial morbidity and mortality worldwide. While vaccines and antiviral treatments exist, the role of dietary factors, particularly fatty fish consumption, in modulating influenza susceptibility remains underexplored. Fatty fish, rich in omega-3 polyunsaturated fatty acids (PUFAs), is believed to influence immune responses, but its specific impact on influenza risk is not fully understood. This study aims to investigate the causal relationship between fatty fish consumption and influenza susceptibility using a two-sample Mendelian randomization (MR) approach.

Methods

Genetic instruments for fatty fish consumption were derived from publicly available genome-wide association studies (GWAS). Summary-level data on influenza susceptibility were sourced from the largest GWAS available. A two-sample MR analysis was conducted using inverse-variance weighted (IVW) and MR-Egger methods to assess the causal effect of fatty fish consumption on influenza risk.

Results

The analysis revealed a potential protective effect of higher fatty fish consumption on influenza susceptibility. Genetically predicted higher intake of fatty fish was associated with a reduced risk of influenza, suggesting that omega-3 PUFAs may help lower susceptibility to the virus. Sensitivity analyses confirmed the absence of horizontal pleiotropy, supporting the robustness of the results.

Conclusion

This study provides evidence for a potential causal relationship between increased fatty fish consumption and a decreased risk of influenza. These findings have implications for dietary recommendations and public health strategies aimed at reducing influenza burden. However, this study has some limitations, such as the potential influence of gene-environment interactions and the predominantly European-based study population, which may limit generalizability. Future research should aim to replicate these findings in diverse populations and further explore the biological mechanisms linking fatty fish intake with influenza susceptibility.

Causal relationship between branched-chain amino acids and leukemia risk: insights from a two-sample Mendelian randomization study

BACKGROUND

Branched-chain amino acids (BCAAs), including leucine, isoleucine, and valine, are essential amino acids involved in protein synthesis, energy metabolism, and immune regulation. While BCAAs are known to influence cancer biology, their role in leukemia remains unclear. This study employs Mendelian randomization (MR) analysis to explore the causal relationship between BCAA levels and four leukemia subtypes: acute myeloid leukemia (AML), acute lymphoblastic leukemia (ALL), chronic lymphocytic leukemia (CLL), and chronic myeloid leukemia (CML).

METHODS

Data from genome-wide association studies (GWAS) were used to select single nucleotide polymorphisms (SNPs) as instrumental variables (IVs) for BCAA levels. The inverse-variance weighted (IVW) method served as the primary analytical approach, with heterogeneity assessed via Cochran's Q test and pleiotropy through MR-Egger intercept. Sensitivity analysis was performed using leave-one-out analysis.

RESULTS

A significant inverse association was observed between total BCAA levels, leucine, valine, and ALL risk. Total BCAA levels showed an odds ratio (OR) of 0.16 (95% CI: 0.05-0.54, p=0.003), leucine 0.17 (95% CI: 0.04-0.61, p=0.007), and valine 0.21 (95% CI: 0.07-0.61, p=0.004). No significant associations were found for AML, CLL, or CML.

CONCLUSION

This study suggests that BCAAs, particularly leucine and valine, may protect against ALL, offering insights into leukemia metabolic regulation and potential targets for prevention and therapy.

Candidate SNP Markers Significantly Altering the Affinity of the TATA-Binding Protein for the Promoters of Human Genes Associated with Primary Open-Angle Glaucoma

Primary open-angle glaucoma (POAG) is the most common form of glaucoma. This condition leads to optic nerve degeneration and eventually to blindness. Tobacco smoking, alcohol consumption, fast-food diets, obesity, heavy weight lifting, high-intensity physical exercises, and many other bad habits are lifestyle-related risk factors for POAG. By contrast, moderate-intensity aerobic exercise and the Mediterranean diet can alleviate POAG. In this work, we for the first time estimated the phylostratigraphic age indices (PAIs) of all 153 POAG-related human genes in the NCBI Gene Database. This allowed us to separate them into two groups: POAG-related genes that appeared before and after the phylum Chordata, that is, ophthalmologically speaking, before and after the camera-type eye evolved. Next, in the POAG-related genes' promoters, we in silico predicted all 3835 candidate SNP markers that significantly change the TATA-binding protein (TBP) affinity for these promoters and, through this molecular mechanism, the expression levels of these genes. Finally, we verified our results against five independent web services-PANTHER, DAVID, STRING, MetaScape, and GeneMANIA-as well as the ClinVar database. It was concluded that POAG is likely to be a symptom of the human self-domestication syndrome, a downside of being civilized.

Mendelian randomization studies in ankylosing spondylitis: A systematic review

INTRODUCTION

Previous research has revealed connections between ankylosing spondylitis (AS) and comorbid conditions. However, observational studies frequently encounter difficulties in establishing definitive causal links between potential risk factors and AS. In contrast, Mendelian randomization (MR) offers a more robust approach to exploring causality by leveraging the random allocation of alleles at birth, thereby minimizing confounding factors.

METHODS

The PubMed, Web of Science, and Cochrane databases were searched for MR studies related to AS with a time frame of database creation to May 2024. Information on authors, exposures, outcomes, data sources, SNPs, MR analysis methods, ORs (95% CIs), and p-values was extracted. Quality assessment was performed using the Critical Appraisal Skills Program (CASP) checklist.

RESULTS

We systematically reviewed 42 MR studies in AS. Health behaviors, comorbidities, and serum markers were involved. Overall, physical activity, inflammatory bowel disease, and specific intestinal flora with serum markers as exposures were causally associated with AS, which leads to an increased risk with several comorbidities.

CONCLUSIONS

MR is a powerful tool for assessing causal relationships between risk factors and outcomes. Specific intestinal flora and inflammatory bowel disease appear to be uncontroversial risk factors that increase the risk of AS. Reliable and robust MR findings may provide a more comprehensive health management strategy for patients with AS.

Genetic association of lipid traits and lipid-related drug targets with normal tension glaucoma: a Mendelian randomization study for predictive preventive and personalized medicine

Background

Glaucoma is the leading cause of irreversible blindness worldwide. Normal tension glaucoma (NTG) is a distinct subtype characterized by intraocular pressures (IOP) within the normal range (< 21 mm Hg). Due to its insidious onset and optic nerve damage, patients often present with advanced conditions upon diagnosis. NTG poses an additional challenge as it is difficult to identify with normal IOP, complicating its prediction, prevention, and treatment. Observational studies suggest a potential association between NTG and abnormal lipid metabolism, yet conclusive evidence establishing a direct causal relationship is lacking. This study aims to explore the causal link between serum lipids and NTG, while identifying lipid-related therapeutic targets. From the perspective of predictive, preventive, and personalized medicine (PPPM), clarifying the role of dyslipidemia in the development of NTG could provide a new strategy for primary prediction, targeted prevention, and personalized treatment of the disease.

Working hypothesis and methods

In our study, we hypothesized that individuals with dyslipidemia may be more susceptible to NTG due to a dysregulation of microvasculature in optic nerve head. To verify the working hypothesis, univariable Mendelian randomization (UVMR) and multivariable Mendelian randomization (MVMR) were utilized to estimate the causal effects of lipid traits on NTG. Drug target MR was used to explore possible target genes for NTG treatment. Genetic variants associated with lipid traits and variants of genes encoding seven lipid-related drug targets were extracted from the Global Lipids Genetics Consortium genome-wide association study (GWAS). GWAS data for NTG, primary open angle glaucoma (POAG), and suspected glaucoma (GLAUSUSP) were obtained from FinnGen Consortium. For apolipoproteins, we used summary statistics from a GWAS study by Kettunen et al. in 2016. For metabolic syndrome, summary statistics were extracted from UK Biobank participants. In the end, these findings could help identify individuals at risk of NTG by screening for lipid dyslipidemia, potentially leading to new targeted prevention and personalized treatment approaches.

Results

Genetically assessed high-density cholesterol (HDL) was negatively associated with NTG risk (inverse-variance weighted [IVW] model: OR per SD change of HDL level = 0.64; 95% CI, 0.49-0.85; P = 1.84 × 10-3), and the causal effect was independent of apolipoproteins and metabolic syndrome (IVW model: OR = 0.29; 95% CI, 0.14-0.60; P = 0.001 adjusted by ApoB and ApoA1; OR = 0.70; 95% CI, 0.52-0.95; P = 0.023 adjusted by BMI, HTN, and T2DM). Triglyceride (TG) was positively associated with NTG risk (IVW model: OR = 1.62; 95% CI, 1.15-2.29; P = 6.31 × 10-3), and the causal effect was independent of metabolic syndrome (IVW model: OR = 1.66; 95% CI, 1.18-2.34; P = 0.003 adjusted by BMI, HTN, and T2DM), but not apolipoproteins (IVW model: OR = 1.71; 95% CI, 0.99-2.95; P = 0.050 adjusted by ApoB and ApoA1). Genetic mimicry of apolipoprotein B (APOB) enhancement was associated with lower NTG risks (IVW model: OR = 0.09; 95% CI, 0.03-0.26; P = 9.32 × 10-6).

Conclusions

Our findings supported dyslipidemia as a predictive causal factor for NTG, independent of other factors such as metabolic comorbidities. Among seven lipid-related drug targets, APOB is a potential candidate drug target for preventing NTG. Personalized health profiles can be developed by integrating lipid metabolism with life styles, visual quality of life such as reading, driving, and walking. This comprehensive approach will aid in shifting from reactive medical services to PPPM in the management of NTG.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13167-024-00373-5.

Association between copper intake and essential hypertension: dual evidence from Mendelian randomization analysis and the NHANES database

Background

Although previous studies have identified an association between trace elements and essential hypertension, the specific trace elements involved and the mechanisms of their association remain unclear. This study aimed to elucidate the relationship between various human trace elements and essential hypertension, thereby addressing existing gaps in the research.

Methods

This study employed two-sample, multivariate, and inverse Mendelian randomization (MR) analyses to investigate the causal relationship between 15 human trace elements as exposure factors and essential hypertension as the outcome. The analysis revealed a statistically significant association between copper intake and essential hypertension. Further validation was conducted using logistic regression models based on data from the National Health and Nutrition Examination Survey (NHANES).

Results

Eighteen trace elements were initially identified through searches in the GWAS database and PubMed. After screening, 15 trace elements were selected as potential exposure factors. MR analysis, utilizing the 2021 genome-wide dataset for essential hypertension, identified copper as a risk factor, showing a positive association with hypertension. Subsequent logistic regression analyses based on NHANES data further confirmed a significant association between dietary copper intake and the risk of essential hypertension, except for the 0.80-1.08 mg/d group in model 3 (p < 0.05). Restricted cubic spline (RCS) analysis indicated a nonlinear relationship between copper intake and the risk of developing essential hypertension.

Conclusion

This study demonstrates a significant association between copper intake and the development of essential hypertension. The findings suggest that higher copper intake is linked to an increased risk of hypertension, underscoring the need to monitor copper intake levels in the prevention and management of this condition.

Gastroesophageal reflux disease and risk for arrhythmias: a Mendelian randomization analysis

Background

Clinical observations and epidemiological studies suggest a potential linkage between gastroesophageal reflux disease (GERD) and arrhythmias, yet the underlying mechanism remains elusive. This study investigates the causal relationship between GERD and four types of arrhythmia through a genetic lens, employing Mendelian randomization analysis to elucidate the directionality of these associations.

Methods

Selected single nucleotide polymorphisms (SNPs) from genome-wide association study (GWAS) data were utilized as instrumental variables. The inverse variance weighting (IVW) method, MR-Egger regression analysis, and the weighted median method were employed in two-sample Mendelian randomization analysis. Horizontal pleiotropy was detected and corrected using the MR-PRESSO test and MR-Egger regression. The stability and reliability of the Mendelian randomization results were assessed using the leave-one-out method, Cochran's Q test, and funnel plots. The causal relationship between GERD and four types of arrhythmias was evaluated using the odds ratio (OR).

Results

IVW results indicated that GERD could increase the risk of arrhythmias. A one standard deviation increases in the logarithmically transformed GERD score resulted in a 34% increase in the risk of arrhythmia (OR = 1.34; 95% CI 1.19-1.51; p = 1.66E-06). No significant correlation was found between GERD and other arrhythmias.

Conclusion

A causal relationship exists between GERD and arrhythmias, suggesting that GERD increases the risk of developing these arrhythmias.

Mendelian randomization supports causality between COVID-19 and glaucoma

To determine whether there is a causal relationship between Corona Virus Disease 2019 (COVID-19) and glaucoma, a 2-sample Mendelian Randomization (MR) design was applied with the main analysis method of inverse-variance-weighted. The reliability of the results was checked using the heterogeneity test, pleiotropy test, and leave-one-out method. Four sets of instrumental variables (IVs) were used to investigate the causality between COVID-19 and glaucoma risk according to data from the IEU Genome Wide Association Study (GWAS). The results showed that 2 sets of COVID-19(RELEASE) were significantly associated with the risk of glaucoma [ID: ebi-a-GCST011071, OR (95% CI) = 1.227 (1.076-1.400), P = .002259; ID: ebi-a-GCST011073: OR (95% CI) = 1.164 (1.022-1.327), P = .022450; 2 sets of COVID-19 hospitalizations were significantly associated with the risk of glaucoma (ID: ebi-a-GCST011081, OR (95% CI) = 1.156 (1.033-1.292), P = .011342; ID: ebi-a-GCST011082: OR (95% CI) = 1.097 (1.007-1.196), P = .034908)]. The sensitivity of the results was acceptable (P > .05) for the 3 test methods. In conclusion, this MR analysis provides preliminary evidence of a potential causal relationship between COVID-19 and glaucoma.

Statins as a risk factor for diabetic retinopathy: a Mendelian randomization and cross-sectional observational study

BACKGROUND

Diabetic retinopathy (DR) is the foremost cause of vision loss among the global working-age population, and statins are among the most frequently prescribed drugs for lipid management in patients with DR. The exact relationship between statins and DR has not been determined. This study sought to validate the causal association between statins usage and diabetic retinopathy.

METHODS

The summary-data-based Mendelian randomization (SMR) method and inverse-variance-weighted Mendelian randomization (IVW-MR) were used to identify the causal relationship between statins and DR via the use of expression quantitative trait loci (eQTL) data for 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR) (31,684 blood samples), low density lipoprotein cholesterol-related GWAS data (sample size: 440,546), and DR-related GWAS data (14,584 cases and 176,010 controls). Additionally, a cross-sectional observational study based on the data from the National Health and Nutrition Examination Survey (NHANES) was conducted to supplement the association between DR and statins (sample size: 106,911). The odds ratios (ORs) with corresponding 95% confidence intervals (CIs) was employed to evaluate the results.

RESULTS

Based on the results of the MR analysis, HMGCR inhibitors were causally connected with a noticeably greater incidence of DR (IVW: OR = 0.54, 95% CI [0.42, 0.69], p = 0.000002; SMR: OR = 0.66, 95% CI [0.52, 0.84], p = 0.00073). Subgroup analysis revealed that the results were not affected by the severity of DR. The sensitivity analysis revealed the stability and reliability of the MR analysis results. The results from the cross-sectional study based on NHANES also support the association between not taking statins and a decreased risk of DR (OR = 0.54, 95% CI [0.37, 0.79], p = 0.001).

CONCLUSIONS

This study revealed that a significant increase in DR risk was causally related to statins use, providing novel insights into the role of statins in DR. However, further investigations are needed to verify these findings.