Multitrait genetic association analysis identifies 50 new risk loci for gastro-oesophageal reflux, seven new loci for Barrett's oesophagus and provides insights into clinical heterogeneity in reflux diagnosis

Crosstalk between gastrointestinal tract disorders and obstructive sleep apnea

PURPOSE

Clinical studies suggested associations between obstructive sleep apnea (OSA) and gastrointestinal tract disorders. This study aims to investigate the genetic causal relationship between OSA and gastrointestinal tract disorders, specifically gastroesophageal reflux disease (GERD) and inflammatory bowel disease (IBD).

METHODS

In this study, we employed two-sample Mendelian Randomization (MR) analysis to investigate the potential relationships between OSA and GERD, and between OSA and IBD. More specifically, the primary analysis utilized inverse variance weighting (IVW). Weighted median, MR Egger, and MR PRESSO were applied to complicate potential violations of MR assumptions. Also, sensitivity analysis was evaluated and similar analysis was performed again after outliers were removed. Additionally, multivariable MR (MVMR) was conducted for associated pairs to adjust for obesity.

RESULTS

Genetically predicted risk of GERD increased OSA risk by approximately 60% (ORIVW = 1.62, 95%CI = [1.43,1.84]) which was also stable by other complicated approaches, and even with BMI adjusted by MVMR (ORadjBMI[95%CI] = 1.26 [1.15,1.37]). Besides, OSA showed a mild causal effect on increased GERD risk after adjusting for obesity (ORadjBMI[95%CI] = 1.05 [1.02,1.08]). Additionally, OSA increased the risks for IBD (ORIVW[95%CI] = 1.36 [1.12,1.65]), including a higher risk of CD (ORIVW[95%CI] = 1.41 [1.08,1.83]), and a trend for increasing UC risk (ORIVW[95%CI] = 1.29 [0.99,1.67]).

CONCLUSION

GERD exerts a substantial causality on increasing the risk of OSA. Conversely, the potential for a causal relationship that OSA contributes to the development of GERD or IBD remains probable. These findings support the crosstalk between gastrointestinal tract disorders and OSA.

Causal effects of genetic birth weight and gestational age on adult esophageal diseases: Mendelian randomization study

BACKGROUND

Few studies have investigated the association between gestational age, birth weight, and esophageal cancer risk; however, causality remains debated. We aimed to establish causal links between genetic gestational age and birth weight traits and gastroesophageal reflux disease (GERD), Barrett’s esophagus (BE), and esophageal adenocarcinoma (EA). Additionally, we explored if known risk factors mediate these links.

AIM

To analyze of the relationship between gestational age, birth weight and GERD, BE, and EA.

METHODS

Genetic data on gestational age and birth weight (n = 84689 and 143677) from the Early Growth Genetics Consortium and outcomes for GERD (n = 467253), BE (n = 56429), and EA (n = 21271) from genome-wide association study served as instrumental variables. Mendelian randomization (MR) and mediation analyses were conducted using MR-Egger, weighted median, and inverse variance weighted methods. Robustness was ensured through heterogeneity, pleiotropy tests, and sensitivity analyses.

RESULTS

Birth weight was negatively correlated with GERD and BE risk [odds ratio (OR) = 0.78; 95% confidence interval (CI): 0.69-0.8] and (OR = 0.75; 95%CI: 0.60-0.9), respectively, with no significant association with EA. No causal link was found between gestational age and outcomes. Birth weight was positively correlated with five risk factors: Educational attainment (OR = 1.15; 95%CI: 1.01-1.31), body mass index (OR = 1.06; 95%CI: 1.02-1.1), height (OR = 1.12; 95%CI: 1.06-1.19), weight (OR = 1.13; 95%CI: 1.10-1.1), and alcoholic drinks per week (OR = 1.03; 95%CI: 1.00-1.06). Mediation analysis showed educational attainment and height mediated the birth weight-BE link by 13.99% and 5.46%.

CONCLUSION

Our study supports the protective role of genetically predicted birth weight against GERD, BE, and EA, independent of gestational age and partially mediated by educational attainment and height.

Migraine and gastroesophageal reflux disease: Disentangling the complex connection with depression as a mediator

OBJECTIVE

Gastroesophageal reflux disease (GERD) and migraine are public health concerns worldwide. No observational study has conclusively elucidated the causal relationship between these two conditions. We employed Mendelian randomization (MR) methods to explore the potential causal links between GERD and migraine.

METHODS

Genome-wide association studies were subjected to MR to infer the causality between GERD and migraine. Bidirectional two-sample MR was performed to establish causal relationships. Multivariable MR analysis was conducted to adjust potential confounding factors, and mediation MR analysis was utilized to assess the role of depression between GERD and migraine as a mediator. We primarily utilized the inverse variance weighted method (IVW) and sensitivity analysis methods, including MR-Egger, weighted median, and leave-one-out methods. We assessed heterogeneity and pleiotropy to ensure the reliability of the results.

RESULTS

Bidirectional two-sample MR revealed a positive causal effect of GERD on migraine (IVW: OR = 1.49, 95% CI: 1.34-1.66, p = 3.70E-13). Migraine did not increase the risk of GERD (IVW: OR = 1.07, 95% CI: 0.98-1.17, p = 0.1139). Multivariable MR indicated that the positive causal effect of GERD on migraine remained after adjustment for factors, such as smoking, alcohol consumption, obesity, type 2 diabetes, and depression. Mediation MR revealed that depression mediated 28.72% of GERD's effect on migraine. MR analysis was supported by all sensitivity analyses and was replicated and validated in another independent dataset on migraine.

CONCLUSION

Our findings elucidate the positive causal effect of GERD on migraine and underscores the mediating role of depression in increasing the risk of migraine due to GERD. Effective control of GERD, particularly interventions targeting depression, may aid in preventing the occurrence of migraine. Future research should delve deeper into the specific pathophysiological mechanisms through which GERD affects migraine risk, facilitating the development of more effective drug targets or disease management strategies.

Relationship between Sjogren's syndrome and gastroesophageal reflux: A bidirectional Mendelian randomization study

The clinical incidence of sjogren's syndrome combined with gastroesophageal reflux disease is high. Existing observational studies have shown inconsistent results in the association between gastroesophageal reflux disease (GERD) and Sjogren's syndrome (SS).We observed that the symptoms of SS patients also improved after receiving GERD-related treatment. Therefore, we aimed to investigate the relationship between GERD and SS through a bidirectional two-sample Mendelian randomization (MR) study. Independent SNPs associated with GERD and SS were selected from a genome-wide association study (GWAS) as instrumental variables to conduct a bidirectional two-sample Mendelian analysis of GERD and SS. Genetic data were obtained from two databases for the following two outcomes: Gastroesophageal reflux (IEU Open GWAS) [sample size = 602,604 (patients = 129,080; nonpatients = 473,524)] and SS (FinnGen) [sample size = 392,423 (patients = 2,495; nonpatients = 389,928)]. Statistical methods for the MR analysis included the inverse-variance weighting method, weighted median, simple mode and weighted mode, as well as heterogeneity and sensitivity analyses using the Cochran Q statistic, MR‒Egger regression, outlier detection methods (MR-PRESSO). In addition, Steiger Test was conducted to test the direction of causality. MR analysis showed a positive correlation between GERD and SS risk [odds ratio (OR) = 1.3279 (95% confidence interval 1.0312-1.7099, P = 0.0280)]. However, in contrast, no significant causal effect of SS on GERD was observed [OR = 1.0024 (95% CI 0.9651-1.0412; P = 0.8995)]. This bidirectional two-sample Mendelian randomization study confirmed a causal relationship between SS and GERD, and suggested that GERD is a risk factor for SS, while SS does not affect GERD.

Gastroesophageal Reflux and Chronic Rhinosinusitis: A Mendelian Randomization Study

OBJECTIVE

Chronic rhinosinusitis (CRS) is associated with gastroesophageal reflux (GERD). However, the causal relationship is controversial. We conducted a two-sample Mendelian Randomization (MR) analysis to explore this potential association.

METHODS

Based on genome-wide association studies (GWAS), a univariable MR was performed to explore the causal relationship of GERD with CRS. Instrumental variables (IVs) pertinent to anti-GERD treatment were employed as a means of validation. The primary MR outcome was established using an inverse variance weighted (IVW) method, supplemented by multiple sensitivity analyses. Subsequently, a multivariable MR was conducted to account for potential confounding variables, thereby ascertaining a direct effect of GERD on CRS. Finally, a network MR analysis was carried out to elucidate the mediating role of asthma in the relationship between GERD and CRS.

RESULTS

The univariable MR demonstrated an association between GERD and an elevated risk of CRS (IVW OR = 1.30, 95% CI = 1.18-1.45, p = 4.19 × 10-7). Omeprazole usage was associated with a reduction in CRS risk (IVW OR = 0.64, 95% CI = 0.42-0.98, p = 0.039). The causal relationship between GERD and CRS remained after adjusting for potential confounders, such as smoking characteristics, body mass index, asthma, allergic rhinitis, in the multivariable MR analysis. Besides, the proportion of the causal effect of GERD on CRS mediated by asthma was 19.65% (95% CI = 2.69%-36.62%).

CONCLUSION

GERD was independently associated with an increased risk of CRS. The mediating role of asthma between GERD and CRS also reveals that GERD is one of the mechanisms underlying unified airway disease.

LEVEL OF EVIDENCE

3 Laryngoscope, 134:3086-3092, 2024.

Causal effect between gut microbiota and gastroesophageal reflux disease: a bidirectional two-sample Mendelian randomization study

Previous observational studies have found that the gut microbiota is closely related to the pathogenesis of gastroesophageal reflux disease (GERD), while their causal relationship is unclear. A two-sample multivariate Mendelian randomization analysis was implemented to estimate the causal effect of gut microbiota on GERD. The gut microbiota aggregated statistics were derived from a meta-analysis of the largest available genome-wide association studies (GWAS) conducted by the MiBioGen alliance ( n  = 13 266). GERD aggregated statistics were derived from published GWAS (129 080 cases and 473 524 controls). A bidirectional two-sample Mendelian randomization study was conducted to explore the causal relationship between gut microbiota and GERD using the inverse variance weighted (IVW), Mendelian randomization Egger, single model, weighted median, and weighted model. To verify the stability of the main results of Mendelian randomization analysis, we performed sensitivity analysis. Based on the results of IVW, we found that Anaerostipes was causally associated with an increased risk of GERD [odds ratio (OR): 1.09, P  = 0.018]. Eight gut microbiota taxa ( Actinobacteria, Bifidobacteriales, Bifidobacteriaceae, Clostridiales vadin BB60 group, Rikenellaceae, Lachnospiraceae UCG004, Methanobrevibacter , and unknown genus id.1000000073 ) are predicted to act causally in suppressing the risk of GERD ( P  < 0.05). In addition, reverse Mendelian randomization analyses revealed that the abundance of 15 gut microbiota taxon was found to be affected by GERD. No significant estimation of heterogeneity or pleiotropy is detected. Our study presents a complicated causal relationship between gut microbiota and GERD that offers guidance on the selection of appropriate probiotics as clinical interventions for GERD.

Genetic correlation between smoking behavior and gastroesophageal reflux disease: insights from integrative multi-omics data

BACKGROUND

Observational studies have preliminarily revealed an association between smoking and gastroesophageal reflux disease (GERD). However, little is known about the causal relationship and shared genetic architecture between the two. This study aims to explore their common genetic correlations by leveraging genome-wide association studies (GWAS) of smoking behavior-specifically, smoking initiation (SI), never smoking (NS), ever smoking (ES), cigarettes smoked per day (CPD), age of smoking initiation(ASI) and GERD.

METHODS

Firstly, we conducted global cross-trait genetic correlation analysis and heritability estimation from summary statistics (HESS) to explore the genetic correlation between smoking behavior and GERD. Then, a joint cross-trait meta-analysis was performed to identify shared "pleiotropic SNPs" between smoking behavior and GERD, followed by co-localization analysis. Additionally, multi-marker analyses using annotation (MAGMA) were employed to explore the degree of enrichment of single nucleotide polymorphism (SNP) heritability in specific tissues, and summary data-based Mendelian randomization (SMR) was further utilized to investigate potential functional genes. Finally, Mendelian randomization (MR) analysis was conducted to explore the causal relationship between the smoking behavior and GERD.

RESULTS

Consistent genetic correlations were observed through global and local genetic correlation analyses, wherein SI, ES, and CPD showed significantly positive genetic correlations with GERD, while NS and ASI showed significantly negative correlations. HESS analysis also identified multiple significantly associated loci between them. Furthermore, three novel "pleiotropic SNPs" (rs4382592, rs200968, rs1510719) were identified through cross-trait meta-analysis and co-localization analysis to exist between SI, NS, ES, ASI, and GERD, mapping the genes MED27, HIST1H2BO, MAML3 as new pleiotropic genes between SI, NS, ES, ASI, and GERD. Moreover, both smoking behavior and GERD were found to be co-enriched in multiple brain tissues, with GMPPB, RNF123, and RBM6 identified as potential functional genes co-enriched in Cerebellar Hemisphere, Cerebellum, Cortex/Nucleus accumbens in SI and GERD, and SUOX identified in Caudate nucleus, Cerebellum, Cortex in NS and GERD. Lastly, consistent causal relationships were found through MR analysis, indicating that SI, ES, and CPD increase the risk of GERD, while NS and higher ASI decrease the risk.

CONCLUSION

We identified genetic loci associated with smoking behavior and GERD, as well as brain tissue sites of shared enrichment, prioritizing three new pleiotropic genes and four new functional genes. Finally, the causal relationship between smoking behavior and GERD was demonstrated, providing insights for early prevention strategies for GERD.

Socioeconomic traits and the risk of Barrett’s esophagus and gastroesophageal reflux disease: A Mendelian randomization study

BACKGROUND

Previous observational studies have shown that the prevalence of gastroesophageal reflux disease (GERD) and Barrett’s esophagus (BE) is associated with socioeconomic status. However, due to the methodological limitations of traditional observational studies, it is challenging to definitively establish causality.

AIM

To explore the causal relationship between the prevalence of these conditions and socioeconomic status using Mendelian randomization (MR).

METHODS

We initially screened single nucleotide polymorphisms (SNPs) to serve as proxies for eight socioeconomic status phenotypes for univariate MR analysis. The inverse variance weighted (IVW) method was used as the primary analytical method to estimate the causal relationship between the eight socioeconomic status phenotypes and the risk of GERD and BE. We then collected combinations of SNPs as composite proxies for the eight socioeconomic phenotypes to perform multivariate MR (MVMR) analyses based on the IVW MVMR model. Furthermore, a two-step MR mediation analysis was used to examine the potential mediation of the associations by body mass index, major depressive disorder (MDD), smoking, alcohol consumption, and sleep duration.

RESULTS

The study identified three socioeconomic statuses that had a significant impact on GERD. These included household income [odds ratio (OR): 0.46; 95% confidence interval (95%CI): 0.31-0.70], education attainment (OR: 0.23; 95%CI: 0.18-0.29), and the Townsend Deprivation Index at recruitment (OR: 1.57; 95%CI: 1.04-2.37). These factors were found to independently and predominantly influence the genetic causal effect of GERD. Furthermore, the mediating effect of educational attainment on GERD was found to be mediated by MDD (proportion mediated: 10.83%). Similarly, the effect of educational attainment on BE was mediated by MDD (proportion mediated: 10.58%) and the number of cigarettes smoked per day (proportion mediated: 3.50%). Additionally, the mediating effect of household income on GERD was observed to be mediated by sleep duration (proportion mediated: 9.75%)

CONCLUSION

This MR study shed light on the link between socioeconomic status and GERD or BE, providing insights for the prevention of esophageal cancer and precancerous lesions.

Socioeconomic traits and the risk of Barrett's esophagus and gastroesophageal reflux disease: A Mendelian randomization study

BACKGROUND

Previous observational studies have shown that the prevalence of gastroesophageal reflux disease (GERD) and Barrett's esophagus (BE) is associated with socioeconomic status. However, due to the methodological limitations of traditional observational studies, it is challenging to definitively establish causality.

AIM

To explore the causal relationship between the prevalence of these conditions and socioeconomic status using Mendelian randomization (MR).

METHODS

We initially screened single nucleotide polymorphisms (SNPs) to serve as proxies for eight socioeconomic status phenotypes for univariate MR analysis. The inverse variance weighted (IVW) method was used as the primary analytical method to estimate the causal relationship between the eight socioeconomic status phenotypes and the risk of GERD and BE. We then collected combinations of SNPs as composite proxies for the eight socioeconomic phenotypes to perform multivariate MR (MVMR) analyses based on the IVW MVMR model. Furthermore, a two-step MR mediation analysis was used to examine the potential mediation of the associations by body mass index, major depressive disorder (MDD), smoking, alcohol consumption, and sleep duration.

RESULTS

The study identified three socioeconomic statuses that had a significant impact on GERD. These included household income [odds ratio (OR): 0.46; 95% confidence interval (95%CI): 0.31-0.70], education attainment (OR: 0.23; 95%CI: 0.18-0.29), and the Townsend Deprivation Index at recruitment (OR: 1.57; 95%CI: 1.04-2.37). These factors were found to independently and predominantly influence the genetic causal effect of GERD. Furthermore, the mediating effect of educational attainment on GERD was found to be mediated by MDD (proportion mediated: 10.83%). Similarly, the effect of educational attainment on BE was mediated by MDD (proportion mediated: 10.58%) and the number of cigarettes smoked per day (proportion mediated: 3.50%). Additionally, the mediating effect of household income on GERD was observed to be mediated by sleep duration (proportion mediated: 9.75%).

CONCLUSION

This MR study shed light on the link between socioeconomic status and GERD or BE, providing insights for the prevention of esophageal cancer and precancerous lesions.

Gastroesophageal reflux disease may causally associate with the increased atrial fibrillation risk: evidence from two-sample Mendelian randomization analyses

Background

The risk of atrial fibrillation (AF) is increased in individuals with gastroesophageal reflux disease (GERD), according to observational research. The causal significance of this association is still unclear. This study sought to assess GERD's role as a potential contributing factor in AF.

Methods

With the use of a two-sample Mendelian randomization (MR) technique, we assessed the causal relationship between GERD and AF. The association of genetic variants with GERD was examined using data from a recent genome-wide association study (GWAS) that included 602,604 people. Data on the association between genetic variations and AF was obtained from a second GWAS with 1,030,836 participants. The effect sizes were examined based on the inverse-variance weighted method. Additional statistical techniques, including MR-Egger, simple mode, weighted mode, MR Pleiotropy Residual Sum, outlier, and weighted median were used in the sensitivity analysis.

Results

MR analyses in inverse-variance weighted models, using 76 single nucleotide polymorphisms (SNPs) as markers, revealed a relationship between genetically predicted GERD and a greater AF incidence [odds ratio (OR): 1.165, 95% CI 1.102-1.231; P = 7.637 × 10-8]. According to MR-Egger, there was no evidence of gene pleiotropy that could be found (intercept = 0.003, P = 0.581). The findings of the sensitivity study, which used several MR methods, were found to be reliable.

Conclusion

The MR analysis revealed a correlation between GERD and increased AF incidence, supporting the idea that treating patients with GERD as early as possible might reduce their chance of developing AF.

Gastroesophageal reflux disease and non-alcoholic fatty liver disease: a two-sample Mendelian randomization combined with meta-analysis

Accumulating evidence from observational studies have suggested an association between gastroesophageal reflux disease (GERD) and non-alcoholic fatty liver disease (NAFLD). However, due to that such studies are prone to biases, we imported Mendelian randomization (MR) to explore whether the causal association between two diseases exsit. Hence, we aimed to analysis the potential association with MR. The single nucleotide polymorphisms (SNPs) of GERD were retrieved from the genome-wide association study dataset as the exposure. The SNPs of NAFLD were taken from the FinnGen dataset as the outcome. The relationship was analyzed with the assistance of inverse variance weighted, MR-Egger, and weighted median. We also uitilized the MR-Egger intercept, Cochran's Q test, leave-one-out analysis, MR-PRESSO, and Steiger directionality test to evaluate the robustness of the causal association. The meta-analysis were also implemented to give an overall evaluation. Finally, our analysis showed a causal relationship between GERD and NAFLD with aid of MR and meta-analysis (OR 1.71 95% CI 1.40-2.09; P < 0.0001).

Potential drug targets for gastroesophageal reflux disease and Barrett's esophagus identified through Mendelian randomization analysis

Gastroesophageal reflux disease (GERD) is a prevalent chronic ailment, and present therapeutic approaches are not always effective. This study aimed to find new drug targets for GERD and Barrett's esophagus (BE). We obtained genetic instruments for GERD, BE, and 2004 plasma proteins from recently published genome-wide association studies (GWAS), and Mendelian randomization (MR) was employed to explore potential drug targets. We further winnowed down MR-prioritized proteins through replication, reverse causality testing, colocalization analysis, phenotype scanning, and Phenome-wide MR. Furthermore, we constructed a protein-protein interaction network, unveiling potential associations among candidate proteins. Simultaneously, we acquired mRNA expression quantitative trait loci (eQTL) data from another GWAS encompassing four different tissues to identify additional drug targets. Meanwhile, we searched drug databases to evaluate these targets. Under Bonferroni correction (P < 4.8 × 10-5), we identified 11 plasma proteins significantly associated with GERD. Among these, 7 are protective proteins (MSP, GPX1, ERBB3, BT3A3, ANTR2, CCM2, and DECR2), while 4 are detrimental proteins (TMEM106B, DUSP13, C1-INH, and LINGO1). Ultimately, C1-INH and DECR2 successfully passed the screening process and exhibited similar directional causal effects on BE. Further analysis of eQTLs highlighted 4 potential drug targets, including EDEM3, PBX3, MEIS1-AS3, and NME7. The search of drug databases further supported our conclusions. Our study indicated that the plasma proteins C1-INH and DECR2, along with 4 genes (EDEM3, PBX3, MEIS1-AS3, and NME7), may represent potential drug targets for GERD and BE, warranting further investigation.

Causal association of gastroesophageal reflux disease with chronic sinusitis and chronic disease of the tonsils and adenoids

BACKGROUND

Exploring bidirectional causal associations between gastroesophageal reflux disease (GERD) and chronic disease of the tonsils and adenoids and chronic sinusitis, respectively.

METHODS

We first conducted a TSMR (two-sample mendelian randomization) study using the results of the inverse variance weighting method as the primary basis and bidirectional MR to rule out reverse causation. Subsequently, MVMR (multivariate MR) analysis was performed to identify phenotypes associated with SNPs and to explore the independent effect of GERD on two outcomes. Finally, we calculated MR-Egger intercepts to assess horizontal polytropy and Cochran's Q statistic to assess heterogeneity and ensure the robustness of the study.

RESULTS

For each standard deviation increase in genetically predicted GERD rate, there was an increased risk of chronic disease of the tonsils and adenoids (OR 1.162, 95% CI 1.036-1.304, P: 1.06E-02) and of developing chronic sinusitis (OR 1.365, 95% CI 1.185-1.572, P: 1.52E-05), and there was no reverse causality. Causality for TSMR was obtained on the basis of IVW (inverse variance weighting) and appeared to be reliable in almost all sensitivity analyses, whereas body mass index may be a potential mediator of causality between GERD and chronic sinusitis.

CONCLUSION

There is a causal association between GERD and chronic disease of the tonsils and adenoids and chronic sinusitis, respectively, and the occurrence of GERD increases the risk of developing chronic disease of the tonsils and adenoids and chronic sinusitis.

Genome-wide cross-disease analyses highlight causality and shared biological pathways of type 2 diabetes with gastrointestinal disorders

Studies suggest links between diabetes and gastrointestinal (GI) traits; however, their underlying biological mechanisms remain unclear. Here, we comprehensively assess the genetic relationship between type 2 diabetes (T2D) and GI disorders. Our study demonstrates a significant positive global genetic correlation of T2D with peptic ulcer disease (PUD), irritable bowel syndrome (IBS), gastritis-duodenitis, gastroesophageal reflux disease (GERD), and diverticular disease, but not inflammatory bowel disease (IBD). We identify several positive local genetic correlations (negative for T2D - IBD) contributing to T2D's relationship with GI disorders. Univariable and multivariable Mendelian randomisation analyses suggest causal effects of T2D on PUD and gastritis-duodenitis and bidirectionally with GERD. Gene-based analyses reveal a gene-level genetic overlap between T2D and GI disorders and identify several shared genes reaching genome-wide significance. Pathway-based study implicates leptin (T2D - IBD), thyroid, interferon, and notch signalling (T2D - IBS), abnormal circulating calcium (T2D - PUD), cardiovascular, viral, proinflammatory and (auto)immune-mediated mechanisms in T2D and GI disorders. These findings support a risk-increasing genetic overlap between T2D and GI disorders (except IBD), implicate shared biological pathways with putative causality for certain T2D - GI pairs, and identify targets for further investigation.

Different effects of 24 dietary intakes on gastroesophageal reflux disease: A mendelian randomization

BACKGROUND

In observational studies, dietary intakes are associated with gastroesophageal reflux disease (GERD).

AIM

To conduct a two-sample mendelian randomization (MR) analysis to determine whether those associations are causal.

METHODS

To explore the relationship between dietary intake and the risk of GERD, we extracted appropriate single nucleotide polymorphisms from genome-wide association study data on 24 dietary intakes. Three methods were adopted for data analysis: Inverse variance weighting, weighted median methods, and MR-Egger's method. The odds ratio (OR) and 95% confidence interval (CI) were used to evaluate the causal association between dietary intake and GERD.

RESULTS

Our univariate Mendelian randomization (UVMR) results showed significant evidence that pork intake (OR, 2.83; 95%CI: 1.76-4.55; P = 1.84 × 10-5), beer intake (OR, 2.70, 95%CI: 2.00-3.64; P = 6.54 × 10-11), non-oily fish intake (OR, 2.41; 95%CI: 1.49-3.91; P = 3.59 × 10-4) have a protective effect on GERD. In addition, dried fruit intake (OR, 0.37; 95%CI: 0.27-0.50; 6.27 × 10-11), red wine intake (OR, 0.34; 95%CI: 0.25-0.47; P = 1.90 × 10-11), cheese intake (OR, 0.46; 95%CI: 0.39-0.55; P =3.73 × 10-19), bread intake (OR, 0.72; 95%CI: 0.56-0.92; P = 0.0009) and cereal intake (OR, 0.45; 95%CI: 0.36-0.57; P = 2.07 × 10-11) were negatively associated with the risk of GERD. There was a suggestive association for genetically predicted coffee intake (OR per one SD increase, 1.22, 95%CI: 1.03-1.44; P = 0.019). Multivariate Mendelian randomization further confirmed that dried fruit intake, red wine intake, cheese intake, and cereal intake directly affected GERD. In contrast, the impact of pork intake, beer intake, non-oily fish intake, and bread intake on GERD was partly driven by the common risk factors for GERD. However, after adjusting for all four elements, there was no longer a suggestive association between coffee intake and GERD.

CONCLUSION

This study provides MR evidence to support the causal relationship between a broad range of dietary intake and GERD, providing new insights for the treatment and prevention of GERD.

Investigating the causal relationship of gut microbiota with GERD and BE: a bidirectional mendelian randomization

BACKGROUND

Gut microbiota(GM) have been proven associated with lots of gastrointestinal diseases, but its causal relationship with Gastroesophageal reflux disease(GERD) and Barrett's esophagus(BE) hasn't been explored. We aimed to uncover the causal relation between GM and GERD/BE and potential mediators by utilizing Mendelian Randomization(MR) analysis.

METHODS

Summary statistics of GM(comprising 301 bacteria taxa and 205 metabolism pathways) were extracted from MiBioGen Consortium(N = 18,340) and Dutch Microbiome Project(N = 7,738), GERD and BE from a multitrait meta-analysis(NGERD=602,604, NBE=56,429). Bidirectional two-sample MR analysis and linkage disequilibrium score regression(LDSC) were used to explore the genetic correlation between GM and GERD/BE. Mediation MR analysis was performed for the risk factors of GERD/BE, including Body mass index(BMI), weight, type 2 diabetes, major depressive disorder(MDD), smoking initiation, alcohol consumption, and dietary intake(including carbohydrate, sugar, fat, protein intake), to detect the potential mediators between GM and GERD/BE.

RESULTS

11 bacterial taxa and 13 metabolism pathways were found associated with GERD, and 18 taxa and 5 pathways exhibited causal relationship with BE. Mediation MR analysis suggested weight and BMI played a crucial role in these relationships. LDSC identified 1 taxon and 4 metabolism pathways related to GERD, and 1 taxon related to BE. Specie Faecalibacterium prausnitzii had a suggestive impact on both GERD(OR = 1.087, 95%CI = 1.01-1.17) and BE(OR = 1.388, 95%CI = 1.03-1.86) and LDSC had determined their correlation. Reverse MR indicated that BE impacted 10 taxa and 4 pathways.

CONCLUSIONS

This study established a causal link between gut microbiota and GERD/BE, and identified the probable mediators. It offers new insights into the role of gut microbiota in the development and progression of GERD and BE in the host.

Gastroesophageal reflux disease and atrial fibrillation: a bidirectional Mendelian randomization study

Background: In observational studies, gastroesophageal reflux disease (GERD) is linked to atrial fibrillation (AF). It is uncertain whether the relationship is due to GERD-induced AF or GERD caused by AF, or confusion with factors related to GERD and AF such as obesity and sleep-disordered breathing. We applied bidirectional Mendelian randomization (MR), in which genetic variations are used as instrumental variables to resolve confounding and reverse causation issues, to determine the causal effect between GERD and AF. Methods: Using summary data from the GERD and AF genome-wide association study (GWAS), a bidirectional MR was performed to estimate the causative impact of GERD on AF risk and AF on GERD risk. The GWAS of GERD meta-analysis comprised 78707 cases and 288734 controls. GWAS summary data for AF, including 45766 AF patients and 191924 controls, were used to genetically predicted AF. The inverse variance weighted (IVW) method was the major MR approach used. MR-PRESSO was implemented to detect heterogeneity and correct the effect of outliers. Weighted median and MR-Egger regression were applied to test heterogeneity and pleiotropy. Results: The genetic instruments of GERD related to increasing the risk of AF, with an OR of 1.339 (95% CI: 1.242-1.444, p < 0.001). However, after removing the outlier 8 SNPs, genetically predicted AF was not associated with an elevated risk of GERD (p = 0.351). Conclusions: Our result suggested that GERD had a causal effect on AF. However, no evidence was identified that AF elevated the risk of GERD.

Causal relationship between air pollution, lung function, gastroesophageal reflux disease, and non-alcoholic fatty liver disease: univariate and multivariate Mendelian randomization study

Background

The association between air pollution, lung function, gastroesophageal reflux disease, and Non-alcoholic fatty liver disease (NAFLD) remains inconclusive. Previous studies were not convincing due to confounding factors and reverse causality. We aim to investigate the causal relationship between air pollution, lung function, gastroesophageal reflux disease, and NAFLD using Mendelian randomization analysis.

Methods

In this study, univariate Mendelian randomization analysis was conducted first. Subsequently, Steiger testing was performed to exclude the possibility of reverse association. Finally, significant risk factors identified from the univariate Mendelian analysis, as well as important factors affecting NAFLD from previous observational studies (type 2 diabetes and body mass index), were included in the multivariable Mendelian randomization analysis.

Results

The results of the univariable Mendelian randomization analysis showed a positive correlation between particulate matter 2.5, gastroesophageal reflux disease, and NAFLD. There was a negative correlation between forced expiratory volume in 1 s, forced vital capacity, and NAFLD. The multivariable Mendelian randomization analysis indicated a direct causal relationship between gastroesophageal reflux disease (OR = 1.537, p = 0.011), type 2 diabetes (OR = 1.261, p < 0.001), and NAFLD.

Conclusion

This Mendelian randomization study confirmed the causal relationships between air pollution, lung function, gastroesophageal reflux, and NAFLD. Furthermore, gastroesophageal reflux and type 2 diabetes were identified as independent risk factors for NAFLD, having a direct causal connection with the occurrence of NAFLD.

The causal associations of circulating lipids with Barrett's Esophagus and Esophageal Cancer: a bi-directional, two sample mendelian randomization analysis

OBJECTIVE

The causal associations of circulating lipids with Barrett's Esophagus (BE) and Esophageal Cancer (EC) has been a topic of debate. This study sought to elucidate the causality between circulating lipids and the risk of BE and EC.

METHODS

We conducted two-sample Mendelian randomization (MR) analyses using single nucleotide polymorphisms (SNPs) of circulating lipids (n = 94,595 - 431,167 individuals), BE (218,792 individuals), and EC (190,190 individuals) obtained from the publicly available IEU OpenGWAS database. The robustness and reliability of the results were ensured by employing inverse-variance weighted (IVW), weighted median, MR-Egger, and MR-PRESSO methods. The presence of horizontal pleiotropy, heterogeneities, and stability of instrumental variables were assessed through MR-Egger intercept test, Cochran's Q test, and leave-one-out sensitivity analysis. Additionally, bidirectional MR and multivariable MR (MVMR) were performed to explore reverse causality and adjust for known confounders, respectively.

RESULTS

None of the testing methods revealed statistically significant horizontal pleiotropy, directional pleiotropy, or heterogeneity. Univariate MR analyses using IVW indicated a robust causal relationship between increased triglycerides and BE (odds ratio [OR] = 1.79, p-value = 0.009), while no significant association with EC was observed. Inverse MR analysis indicated no evidence of reverse causality in the aforementioned outcomes. In MVMR analyses, elevated triglycerides (TRG) were significantly and positively associated with BE risk (OR = 1.79, p-value = 0.041).

CONCLUSION

This MR study suggested that genetically increased triglycerides were closely related to an elevated risk of BE, potentially serving as a biomarker for the diagnosis of BE in the future.

The causal relationship between genetically predicted blood metabolites and idiopathic pulmonary fibrosis: A bidirectional two-sample Mendelian randomization study

BACKGROUND

Numerous metabolomic studies have confirmed the pivotal role of metabolic abnormalities in the development of idiopathic pulmonary fibrosis (IPF). Nevertheless, there is a lack of evidence on the causal relationship between circulating metabolites and the risk of IPF.

METHODS

The potential causality between 486 blood metabolites and IPF was determined through a bidirectional two-sample Mendelian randomization (TSMR) analysis. A genome-wide association study (GWAS) involving 7,824 participants was performed to analyze metabolite data, and a GWAS meta-analysis involving 6,257 IPF cases and 947,616 control European subjects was conducted to analyze IPF data. The TSMR analysis was performed primarily with the inverse variance weighted model, supplemented by weighted mode, MR-Egger regression, and weighted median estimators. A battery of sensitivity analyses was performed, including horizontal pleiotropy assessment, heterogeneity test, Steiger test, and leave-one-out analysis. Furthermore, replication analysis and meta-analysis were conducted with another GWAS dataset of IPF containing 4,125 IPF cases and 20,464 control subjects. Mediation analyses were used to identify the mediating role of confounders in the effect of metabolites on IPF.

RESULTS

There were four metabolites associated with the elevated risk of IPF, namely glucose (odds ratio [OR] = 2.49, 95% confidence interval [95%CI] = 1.13-5.49, P = 0.024), urea (OR = 6.24, 95% CI = 1.77-22.02, P = 0.004), guanosine (OR = 1.57, 95%CI = 1.07-2.30, P = 0.021), and ADpSGEGDFXAEGGGVR (OR = 1.70, 95%CI = 1.00-2.88, P = 0.0496). Of note, the effect of guanosine on IPF was found to be mediated by gastroesophageal reflux disease. Reverse Mendelian randomization analysis displayed that IPF might slightly elevate guanosine levels in the blood.

CONCLUSION

Conclusively, hyperglycemia may confer a promoting effect on IPF, highlighting that attention should be paid to the relationship between diabetes and IPF, not solely to the diagnosis of diabetes. Additionally, urea, guanosine, and ADpSGEGDFXAEGGGVR also facilitate the development of IPF. This study may provide a reference for analyzing the potential mechanism of IPF and carry implications for the prevention and treatment of IPF.

The association between tea consumption and non-malignant digestive system diseases: A Mendelian randomized study

BACKGROUND

Tea consumption might be closely related to non-malignant digestive diseases. Nevertheless, this correlation remains inadequately comprehended. Therefore, our objective was to elucidate the essence of these connections.

METHODS

This study employed a Mendelian randomization approach to investigate the impact of tea consumption on specific digestive disorders. Genetic data associated with tea consumption were obtained from the UK Biobank (UKB), encompassing 447,485 participants. We chose a gene-wide association study with no sample overlap and UKB as our data source for all outcomes. The primary analytical method utilized was inverse variance weighting, and multiple analytical models were employed to enhance the analysis's reliability and ensure robust results.

RESULT

Our investigation revealed that tea consumption was linked to an elevated susceptibility to gastroesophageal reflux disease (GERD). However, there was a lack of substantial evidence suggesting an association between tea intake and Crohn's disease (CD), ulcerative colitis (UC), or non-alcoholic fatty liver disease (NAFLD).

CONCLUSIONS

Our study suggests that the excessive consumption of tea may heighten the likelihood of GERD. These results hold potential significance in guiding dietary pattern modifications for individuals with GERD. Furthermore, there may be value in implementing GERD monitoring and preventive measures in populations with elevated tea consumption.

Modifiable risk factors mediate the effect of gastroesophageal reflux disease on stroke and subtypes: A Mendelian randomization study

OBJECTIVES

Previous observational studies have suggested that gastroesophageal reflux disease (GERD) increases the risk of stroke, but the specific underlying mechanisms are unclear. We investigated the causal associations of GERD with stroke and its subtypes using Mendelian randomization (MR), and evaluated the potential mediating effects of modifiable stroke risk factors in the causal pathway.

METHODS

Genetic instrumental variables for GERD were extracted from the latest genome-wide association study (GWAS) summary level data. We initially performed two-sample MR to examine the association of GERD with stroke and its subtypes, including ischemic stroke, intracranial hemorrhage, and the major subtypes of ischemic stroke. Two-step MR was further employed to investigate the mediating effect of 15 risk factors in the causal pathway.

RESULTS

We found significant causal associations of genetically predicted GERD with increased risk of stroke (OR: 1.22 95% CI: 1.126-1.322), ischemic stroke (OR: 1.19 95% CI: 1.098-1.299), and large-artery stroke (OR: 1.49 95% CI: 1.214-1.836). Replication and sensitivity analyses yielded consistent effect directions and similar estimates. Further mediation analyses indicated that hypertension (HTN), systolic blood pressure (SBP), and type 2 diabetes (T2D) mediated 36.0%, 9.0%, and 15.8% of the effect of GERD on stroke; 42.9%, 10.8%, and 21.4% for ischemic stroke, and 23.3%; 7.9%, and 18.7% for large-artery stroke, respectively.

CONCLUSIONS

This study supports that GERD increases susceptibility to stroke, ischemic stroke, and large-artery stroke, and is partially mediated by HTN, SBP, and T2D.

Gastroesophageal reflux disease with 6 neurodegenerative and psychiatric disorders: Genetic correlations, causality, and potential molecular mechanisms

The comorbidities between gastroesophageal reflux disease (GERD) and various neurodegenerative and psychiatric disorders have been widely reported. However, the genetic correlations, causal relationships, and underlying mechanisms linking GERD to these disorders remain largely unknown. Here, we conducted a bidirectional Mendelian randomization (MR) analysis to determine the causality between GERD and 6 neurodegenerative and psychiatric disorders. Sensitivity analyses and multivariable MR were performed to test the robustness of our findings. Linkage disequilibrium score regression was used to assess the genetic correlation between these diseases as affected by heredity. Multiple bioinformatics tools combining two machine learning algorithms were applied to further investigate the potential mechanisms underlying these diseases. We found that genetically predicted GERD significantly increased the risk of Alzheimer's disease, major depressive disorder, and anxiety disorders. There might be a bidirectional relationship between GERD and insomnia. GERD has varying degrees of genetic correlations with AD, ALS, anxiety disorders, insomnia, and depressive disorder. Bioinformatics analyses revealed the hub shared genes and the common pathways between GERD and 6 neurodegenerative and psychiatric disorders. Our findings demonstrated the complex nature of the genetic architecture across these diseases and clarified their causality, highlighting that treatments for the cure or remission of GERD may serve as potential strategies for preventing and managing neurodegenerative and psychiatric disorders.

Causal association of gastroesophageal reflux disease on irritable bowel syndrome: a two-sample Mendelian randomization study

Background

Recently, observational studies have reported that gastroesophageal reflux disease (GERD) is commonly associated with irritable bowel syndrome (IBS), but the causal relationship is unclear.

Methods

We conducted a two-sample Mendelian randomization study using summary data from genome-wide association studies (GWASs) to explore a causal relationship between GERD (N cases = 129,080) and IBS (N cases = 4,605) of European ancestry. Furthermore, the inverse-variance weighted (IVW) method and a series of sensitivity analyses were used to assess the accuracy and confidence of our results.

Results

We found a significant association of GERD with IBS (NSNP = 74; OR: 1.375; 95% CI: 1.164-1.624; p < 0.001). Reverse MR analysis showed no evidence of a causal association for IBS with GERD (NSNP = 6; OR: 0.996; 95% CI: 0.960-1.034; p = 0.845).

Conclusion

This study provides evidence that the presence of GERD increases the risk of developing IBS, and it is observed from the reverse MR results that IBS did not increase the risk of GERD.

The Role of Inflammatory Biomarkers in Mediating the Effect of Inflammatory Bowel Disease on nonmalignant Digestive System Diseases: A Multivariable Mendelian Randomized Study

Background

While observation studies have shown a positive correlation between inflammatory bowel disease (IBD) and the risk of nonmalignant digestive system diseases, a definitive causal relationship has not yet been clearly established.

Methods

Mendelian randomization (MR) was employed to investigate the potential causal association between genetic susceptibility to IBD and nonmalignant gastrointestinal diseases. Genetic variants were extracted as instrumental variables (IVs) from a genome-wide association study (GWAS) meta-analysis, which included 12,194 cases of Crohn's disease (CD) and 28,072 control cases of European ancestry. The GWAS for ulcerative colitis (UC) included 12,366 UC and 33,609 control cases of European ancestry. All IVs reached genome-wide significance (GWAS p value <5 × 10-8). Summary-level data for acute pancreatitis (AP), irritable bowel syndrome (IBS), gastroesophageal reflux disease, cholelithiasis, and CeD (celiac disease) were obtained from the GWAS meta-analysis and the FinnGen dataset. Summary-level data on relevant inflammatory factors were provided by the International Genetic Consortium. Univariate MR analysis was conducted using inverse variance weighting as the primary method for estimating causal effects. Multivariate MR analyses were also performed to detect possible mediators.

Results

Genetic susceptibility to UC was associated with an increased risk of AP (OR = 1.08; 95% CI = 1.03-1.13; p=0.002) and IBS odds ratio (OR] = 1.07; 95% confidence interval (CI] = 1.03-1.11; (p < 0.001). In terms of potential mediators, interleukin 6 (IL-6) had a driving effect on the association between UC and AP. There was no apparent evidence of increased risk with CD. Meanwhile, genetic susceptibility to CD increases the risk of CeD (OR = 1.14; 95% CI = 1.03-1.25; p=0.01).

Conclusions

The evidence suggests that UC is associated with an elevated risk of AP and IBS, and IL-6 may be responsible in AP. CD is associated with an increased risk of developing CeD. Implementing a proactive monitoring program for assessing the risk of gastrointestinal diseases in UC patients, particularly those with elevated IL-6 levels, may be of interest. In addition, the presence of AP and IBS may indicate the presence of UC. Preventing CeD is an essential consideration in the therapeutic management of patients with CD.

Gastroesophageal reflux disease increases the risk of essential hypertension: results from the Nationwide Readmission Database and Mendelian randomization analysis

BACKGROUND

The link between gastroesophageal reflux disease (GERD) and essential hypertension (EH) and its causal nature remains controversial. Our study examined the connection between GERD and the risk of hypertension and assessed further whether this correlation has a causal relationship.

METHODS

First, we utilized the National Readmission Database including 14 422 183 participants to conduct an observational study. Dividing the population into GERD and non-GERD groups, we investigated the correlation between GERD and EH using multivariate logistic regression. Next, bidirectional two-sample Mendelian randomization was adopted. The summary statistics for GERD were obtained from a published genome-wide association study including 78 707 cases and 288 734 controls. We collected summary statistics for hypertension containing 70 651 cases and 223 663 controls from the FinnGen consortium. We assessed causality primarily by the inverse-variance weighted method with validation by four other Mendelian randomization approaches as well as an array of sensitivity analyses.

RESULTS

In the unadjusted model, GERD patients had a higher risk of EH than the non-GERD group, regardless of gender (odds ratio, 1.43; 95% confidence interval: 1.42-1.43; P < .001). Further adjusting for critical confounders did not change this association. For Mendelian randomization, we found that genetically predicted GERD was causally linked to an enhanced risk of EH in inverse-variance weighted technique (odds ratio, 1.52; 95% confidence interval: 1.39-1.67; P = 3.51 × 10-18); conversely, EH did not raise the risk of GERD causally.

CONCLUSIONS

GERD is a causal risk factor for EH. Further research is required to probe the mechanism underlying this causal connection.

Causal analysis of gastroesophageal reflux disease and esophageal cancer

Patients with gastroesophageal reflux disease (GERD) are more likely to develop esophageal cancer (EC). However, a causal relationship between the 2 has been difficult to determine. Therefore, this study aimed to evaluate the impact of GERD on EC using the Mendelian randomization (MR) method. The causal association between GERD and EC was analyzed based on 2 publicly available genetic summary datasets for the GERD cohort (129,080 cases vs 473,524 controls) and the EC cohort (740 cases vs 372,016 controls). The causal inference was mainly evaluated by the inverse variance weighted MR. The MR-Egger regression, MR Pleiotropy Residual Sum and Outlier test, and leave-one-out test were used to confirm the sensitivity of the MR results. Possible interfering factors were excluded by multivariate MR (MVMR) analysis. We used 73 single nucleotide polymorphisms as instrumental variables. GERD was associated with increasing EC risk (odds ratio [OR], 1.001; 95% confidence interval, 1.001-1.002; P < .001), which was identified using the inverse variance weighted method. The sensitivity analysis also demonstrated similar results with the causal explanation, and major bias in genetic pleiotropy was not identified (intercept, 0.001; standard error, 0.001; P = .418). The multivariate MR analysis demonstrated the effect of GERD on EC even after excluding possible mediating factors (OR, 1.003; 95% confidence interval, 1.001-1.005; P = .012). This study confirmed that GERD has a causal effect on EC. Therefore, interventional measures are recommended to prevent EC.

A Mendelian randomization analysis identifies causal association between sarcopenia and gastroesophageal reflux disease

The incidence of gastroesophageal reflux disease (GERD) is increasing with the advancement of world population aging, affecting the population health worldwide. Recently, there were several researches to suggest the association between GERD and sarcopenia, but evidence supporting the causal effect was absent. The purpose of this study is to determine the causal relationship between GERD and sarcopenia through a Mendelian randomization (MR) study. We conducted an MR analysis by using summary-level data of genome-wide association studies (GWASs) in the European population. The inverse variance weighted (IVW) method was used as the primary analytical method for evaluating causality. In addition, four other MR methods were performed to supplement the IVW results. We also used the Mendelian randomization pleiotropy residual sum and outlier (MR-PRESSO) and the multivariable Mendelian randomization (MVMR) to validate the robustness of our results. IVW analysis revealed a causally positive correlation between low hand grip strength (OR = 1.2358, 95% C.I.: 1.0521-1.4514, P = 0.0099), decreased walking pace (OR = 0.1181, 95% C.I.: 0.0838-0.1666, P = 4×10-34), and decreased appendicular lean mass (ALM) (OR = 0.8612, 95% C.I.: 0.8263-0.8975, P = 1×10-12) and GERD. MR-PRESSO and MVMR analysis confirmed the association evidence. In conclusion, this MR analysis supported the causal association between sarcopenia-related traits and GERD.

Causal relationships between dietary habits and Barrett's esophagus risk: a univariable and multivariable Mendelian randomization study

Aims: Dietary habits are reported to be associated with Barrett's esophagus (BE) risk; however, whether there is a causal relationship remains controversial. Here, we systematically examined the causal effects of genetically predicted dietary habits on BE risk through a Mendelian randomization (MR) analysis approach. Methods: Data for exposures were obtained from the UK Biobank (UKB), while the summary-level data for outcomes were obtained from a large sample-size GWAS meta-analysis. Genetic variants associated with 17 ordinary dietary habits at the genome-wide significance level were regarded as instrumental variables (IVs). Univariable and multivariable MR analyses were conducted to explore the causal relationships between dietary habits and BE risk. Sensitivity analyses were implemented to evaluate robustness of the results and determine the potential pleiotropy bias. Results: Univariable MR (UVMR) analysis showed that genetic predisposition to alcohol intake frequency, cooked vegetable intake, beef intake, bread intake, fresh fruit intake, salad/raw vegetable intake, and dried fruit intake were associated with BE risk, with all P values <0.05. After adjusting confounders, the effects of four dietary habits on BE risk persisted; multivariable MR (MVMR) analysis revealed that alcohol intake frequency (adjusted odds ratio (OR) = 1.74 (1.34, 2.27); P = 3.42 × 10-5) was causally associated with higher BE risk, the cooked vegetable intake (adjusted OR = 2.64 (1.16, 5.97); P = 0.02) had suggestively increased BE risk, while higher consumption of bread (adjusted OR = 0.54 (0.32-0.91); P = 0.02) and fresh fruit (adjusted OR = 0.34 (0.15, 0.77); P = 0.01) were suggestively associated with lower BE risk. Conclusions: These MR analyses demonstrate evidence of causal relationships between dietary habits and BE risk. These findings provide new insights into targeted dietary intervention strategies for BE prevention.

Genetic correlation, shared loci, but no causality between bipolar disorder and inflammatory bowel disease: A genome-wide pleiotropic analysis

BACKGROUND AND AIMS

The comorbidity between bipolar disorder (BD) and inflammatory bowel disease (IBD) has been widely reported in observational studies. However, unclear whether this comorbidity reflects a shared genetic architecture.

METHODS

Leveraging large-scale genome-wide association study (GWAS) summary statistics of BD, IBD and its subtypes, ulcerative colitis (UC) and Crohn's disease (CD), we performed a genome-wide pleiotropic analysis to estimate heritability and genetic correlation, identify pleiotropy loci/genes, and explore the shared biological pathway. Mendelian randomization (MR) studies were subsequently employed to infer whether the potential causal relationship is present.

RESULTS

We found a positive significant genetic correlation between BD and IBD (rg = 0.10, P = 7.00 × 10-4), UC (rg = 0.09, P = 2.90 × 10-3), CD (rg = 0.08, P = 6.10 × 10-3). In cross-trait meta-analysis, a total of 29, 24, and 23 independent SNPs passed the threshold for significant association between BD and IBD, UC, and CD, respectively. We identified five novel pleiotropy genes including ZDHHC2, SCRN1, INPP4B, C1orf123, and BRD3 in both BD and IBD, as well as in its subtypes UC and CD. Pathway enrichment analyses revealed that those pleiotropy genes were mainly enriched in several immune-related signal transduction pathways and cerebral disease-related pathways. MR analyses provided no evidence for a causal relationship between BD and IBD.

CONCLUSION

Our findings corroborated that shared genetic basis and common biological pathways may explain the comorbidity of BD and IBD. These findings further our understanding of shared genetic mechanisms underlying BD and IBD, and potentially provide points of intervention that may allow the development of new therapies for these co-occurrent disorders.

Mendelian randomization analysis reveals the impact of physical and occupational activities on the risk of gastroesophageal reflux disease and Barrett's esophagus

BACKGROUND

Recent studies have indicated that participating in physical activity may provide a safeguard against gastroesophageal reflux disease (GERD). Nevertheless, the precise links between physical and occupational activity and the occurrence of GERD and Barrett's esophagus (BE) are still uncertain.

METHODS

Conducting univariate and multivariate Mendelian randomization investigations to examine the causal relationship between exposures and outcomes. Genetic variation simulation was used in randomized experiments. Data on physical and occupational activity were obtained from the UK Biobank and GWAS catalog. In the meantime, data on GERD and BE were extracted from a high quality meta-analysis.

RESULTS

The results of univariate Mendelian randomization analysis using multiple methods suggest a causal relationship between strenuous sports or other forms of exercise (as a protective factor) and GERD/BE. At the same time, three types of occupational related physical activities, including heavy manual or physical work, shift work and walking or standing work, are risk factors for GERD/BE and have a causal relationship with them. These results were reconfirmed through multivariate Mendelian randomization analysis, which excluding the influence of other potential confounding factors.

CONCLUSIONS

The findings indicated that strenuous sports or other forms of exercise could lower the likelihood of GERD/BE, while excessive physical strain in the workplace, prolonged periods of standing or walking, and shift work could raise the risk of GERD/BE. Acknowledging this risk and implementing suitable measures can contribute to the prevention of GERD and BE, thus mitigating the associated health burden.

Causal relationship between gut microbiota and risk of gastroesophageal reflux disease: a genetic correlation and bidirectional Mendelian randomization study

Background

Numerous observational studies have identified a linkage between the gut microbiota and gastroesophageal reflux disease (GERD). However, a clear causative association between the gut microbiota and GERD has yet to be definitively ascertained, given the presence of confounding variables.

Methods

The genome-wide association study (GWAS) pertaining to the microbiome, conducted by the MiBioGen consortium and comprising 18,340 samples from 24 population-based cohorts, served as the exposure dataset. Summary-level data for GERD were obtained from a recent publicly available genome-wide association involving 78 707 GERD cases and 288 734 controls of European descent. The inverse variance-weighted (IVW) method was performed as a primary analysis, the other four methods were used as supporting analyses. Furthermore, sensitivity analyses encompassing Cochran's Q statistics, MR-Egger intercept, MR-PRESSO global test, and leave-one-out methodology were carried out to identify potential heterogeneity and horizontal pleiotropy. Ultimately, a reverse MR assessment was conducted to investigate the potential for reverse causation.

Results

The IVW method's findings suggested protective roles against GERD for the Family Clostridiales Vadin BB60 group (P = 0.027), Genus Lachnospiraceae UCG004 (P = 0.026), Genus Methanobrevibacter (P = 0.026), and Phylum Actinobacteria (P = 0.019). In contrast, Class Mollicutes (P = 0.037), Genus Anaerostipes (P = 0.049), and Phylum Tenericutes (P = 0.024) emerged as potential GERD risk factors. In assessing reverse causation with GERD as the exposure and gut microbiota as the outcome, the findings indicate that GERD leads to dysbiosis in 13 distinct gut microbiota classes. The MR results' reliability was confirmed by thorough assessments of heterogeneity and pleiotropy.

Conclusions

For the first time, the MR analysis indicates a genetic link between gut microbiota abundance changes and GERD risk. This not only substantiates the potential of intestinal microecological therapy for GERD, but also establishes a basis for advanced research into the role of intestinal microbiota in the etiology of GERD.

Causal associations between gastroesophageal reflux disease and essential hypertension: A bidirectional Mendelian randomization study

BACKGROUND

Clinical studies have reported that patients with gastroesophageal reflux disease (GERD) have a higher prevalence of hypertension.

AIM

To performed a bidirectional Mendelian randomization (MR) analysis to investigate the causal link between GERD and essential hypertension.

METHODS

Eligible single nucleotide polymorphisms (SNPs) were selected, and weighted median, inverse variance weighted (IVW) as well as MR egger (MR-Egger) regression were used to examine the potential causal association between GERD and hypertension. The MR-Pleiotropy RESidual Sum and Outlier analysis was used to detect and attempt to reduce horizontal pleiotropy by removing outliers SNPs. The MR-Egger intercept test, Cochran's Q test and "leave-one-out" sensitivity analysis were performed to evaluate the horizontal pleiotropy, heterogeneities, and stability of single instrumental variable.

RESULTS

IVW analysis exhibited an increased risk of hypertension (OR = 1.46, 95%CI: 1.33-1.59, P = 2.14E-16) in GERD patients. And the same result was obtained in replication practice (OR = 1.002, 95%CI: 1.0008-1.003, P = 0.000498). Meanwhile, the IVW analysis showed an increased risk of systolic blood pressure (β = 0.78, 95%CI: 0.11-1.44, P = 0.021) and hypertensive heart disease (OR = 1.68, 95%CI: 1.36-2.08, P = 0.0000016) in GERD patients. Moreover, we found an decreased risk of Barrett's esophagus (OR = 0.91, 95%CI: 0.83-0.99, P = 0.043) in essential hypertension patients.

CONCLUSION

We found that GERD would increase the risk of essential hypertension, which provided a novel prevent and therapeutic perspectives of essential hypertension.

Identifying causal relationships between gastroesophageal reflux and extraesophageal diseases: A Mendelian randomization study

Traditional observational and in vivo studies have suggested an etiological link between gastroesophageal reflux disease (GERD) and the development of extraesophageal diseases (EEDs), such as noncardiac chest pain. However, evidence demonstrating potential causal relationships is lacking. This study evaluated the potential causal relationship between GERD and EEDs, including throat and chest pain, asthma, bronchitis, chronic rhinitis, nasopharyngitis and pharyngitis, gingivitis and periodontal disease, cough, using multiple Mendelian randomization (MR) methods, and sensitivity analysis was performed. The Mendelian randomization Pleiotropy RESidual Sum and Outlier and PhenoScanner tools were used to further check for heterogeneous results and remove outliers. MR with inverse-variance weighted (IVW) showed a significant causal relationship between GERD and EEDs after Bonferroni correction. IVW results indicated that GERD increased the risk of chronic rhinitis, nasopharyngitis and pharyngitis (odds ratio [OR] = 1.482, 95% confidence interval [CI] = 1.267-1.734, P < .001], gingivitis and periodontal disease (OR = 1.166, 95% CI = 1.046-1.190, P = .001), throat and chest pain (OR = 1.585, 95% CI = 1.455-1.726, P < .001), asthma (OR = 1.539, 95% CI = 1.379-1.717, P < .001), and bronchitis (OR = 1.249, 95% CI = 1.168-1.335, P < .001). Sensitivity analysis did not detect pleiotropy. Leave-one-out analysis shows that MR results were not affected by individual single nucleotide polymorphisms. The funnel plot considers the genetic instrumental variables to be almost symmetrically distributed. This MR supports a causal relationship among GERD and EEDs. Precise moderation based on causality and active promotion of collaboration among multidisciplinary physicians ensure high-quality diagnostic and treatment recommendations and maximize patient benefit.

Elucidating shared biomarkers in gastroesophageal reflux disease and idiopathic pulmonary fibrosis: insights into novel therapeutic targets and the role of angelicae sinensis radix

Background: The etiological underpinnings of gastroesophageal reflux disease (GERD) and idiopathic pulmonary fibrosis (IPF) remain elusive, coupled with a scarcity of effective therapeutic interventions for IPF. Angelicae sinensis radix (ASR, also named Danggui) is a Chinese herb with potential anti-fibrotic properties, that holds promise as a therapeutic agent for IPF. Objective: This study seeks to elucidate the causal interplay and potential mechanisms underlying the coexistence of GERD and IPF. Furthermore, it aims to investigate the regulatory effect of ASR on this complex relationship. Methods: A two-sample Mendelian randomization (TSMR) approach was employed to delineate the causal connection between gastroesophageal reflux disease and IPF, with Phennoscanner V2 employed to mitigate confounding factors. Utilizing single nucleotide polymorphism (SNPs) and publicly available microarray data, we analyzed potential targets and mechanisms related to IPF in GERD. Network pharmacology and molecular docking were employed to explore the targets and efficacy of ASR in treating GERD-related IPF. External datasets were subsequently utilized to identify potential diagnostic biomarkers for GERD-related IPF. Results: The IVW analysis demonstrated a positive causal relationship between GERD and IPF (IVW: OR = 1.002, 95%CI: 1.001, 1.003; p < 0.001). Twenty-five shared differentially expressed genes (DEGs) were identified. GO functional analysis revealed enrichment in neural, cellular, and brain development processes, concentrated in chromosomes and plasma membranes, with protein binding and activation involvement. KEGG analysis unveiled enrichment in proteoglycan, ERBB, and neuroactive ligand-receptor interaction pathways in cancer. Protein-protein interaction (PPI) analysis identified seven hub genes. Network pharmacology analysis demonstrated that 104 components of ASR targeted five hub genes (PDE4B, DRD2, ERBB4, ESR1, GRM8), with molecular docking confirming their excellent binding efficiency. GRM8 and ESR1 emerged as potential diagnostic biomarkers for GERD-related IPF (ESR1: AUCGERD = 0.762, AUCIPF = 0.725; GRM8: AUCGERD = 0.717, AUCIPF = 0.908). GRM8 and ESR1 emerged as potential diagnostic biomarkers for GERD-related IPF, validated in external datasets. Conclusion: This study establishes a causal link between GERD and IPF, identifying five key targets and two potential diagnostic biomarkers for GERD-related IPF. ASR exhibits intervention efficacy and favorable binding characteristics, positioning it as a promising candidate for treating GERD-related IPF. The potential regulatory mechanisms may involve cell responses to fibroblast growth factor stimulation and steroidal hormone-mediated signaling pathways.

Association between gastroesophageal reflux disease and stroke: a bidirectional Mendelian randomization study

Objective

Some previous studies have suggested a potential link between stroke and gastroesophageal reflux disease (GERD). We used a two-sample bidirectional Mendelian randomization (MR) method to explore the causal relationship between stroke and GERD.

Design

Summary-level data derived from the published genome-wide association studies (GWAS) were employed for analyses. Single-nucleotide polymorphisms (SNPs) as instrumental variables (IVs) for stroke (n = 446,696) and its common subtypes ischemic stroke (IS) (n = 440,328), large vessel stroke (LVS) (n = 410,484), small vessel stroke (SVS) (n = 198,048), and cardioembolic stroke (CES) (n = 413,304) were obtained from the MEGASTROKE consortium. The data on intracerebral hemorrhage (ICH) (n = 721,135) come from the UK Biobank. Instrumental variables (IVs) for lacunar stroke (LS) (n = 474,348) and GERD (n = 602,604) were screened from publicly available genetic summary data. The inverse variance weighted (IVW) method was used as the main MR method. Pleiotropy was detected by the MR-Egger intercept test, MR pleiotropy residual sum and outlier, and leave-one-out analysis. Cochran Q statistics were used as supplements to detect pleiotropy.

Results

We found that GERD can causally increase the risk of stroke [IVW odds ratio (OR): 1.22, 95% confidence interval (CI): 1.13-1.32, p = 1.16 × 10-6] and its common subtypes IS (OR: 1.19, 95% CI: 1.10-1.30, p = 3.22 × 10-5), LVS (OR: 1.49, 95% CI: 1.21-1.84, p = 1.47 × 10-4), and LS (OR: 1.20, 95% CI: 1.001-1.44, p = 0.048). Several important risk factors for stroke have also been implicated in the above causal relationship, including type 2 diabetes, sleep apnea syndrome, high body mass index, high waist-to-hip ratio, and elevated serum triglyceride levels. In reverse MR analysis, we found that overall stroke (OR: 1.09, 95% CI: 1.004-1.19, p = 0.039) and IS (OR: 1.10, 95% CI: 1.03-1.17, p = 0.007) have the causal potential to enhance GERD risk.

Conclusion

This MR study provides evidence supporting a causal relationship between GERD and stroke and some of its common subtypes. We need to further explore the interconnected mechanisms between these two common diseases to better prevent and treat them.

Gastroesophageal reflux disease and the risk of respiratory diseases: a Mendelian randomization study

BACKGROUND

Observational studies have suggested a suspected association between gastroesophageal reflux disease (GERD) and respiratory diseases, but the causality remains equivocal. The goal of this study was to evaluate the causal role of GERD in respiratory diseases by employing Mendelian randomization (MR) studies.

METHODS

We conducted Mendelian randomization analysis based on summary data of genome-wide association studies (GWASs) and three MR statistical techniques (inverse variance weighted, weighted median and MR-Egger) were employed to assess the probable causal relationship between GERD and the risk of respiratory diseases. Sensitivity analysis was also carried out to ensure more trustworthy results, which involves examining the heterogeneity, pleiotropy and leave-one-SNP-out method. We also identified 33 relevant genes and explored their distribution in 26 normal tissues.

RESULTS

In the analysis, for every unit increase in developing GERD, the odds ratio for developing COPD, bronchitis, pneumonia, lung cancer and pulmonary embolism rose by 72% (ORIVW = 1.72, 95% CI 1.50; 1.99), 19% (ORIVW = 1.19, 95% CI 1.11; 1.28), 16% (ORIVW = 1.16, 95% CI 1.07; 1.26), 0. 3% (ORIVW = 1.003, 95% CI 1.0012; 1.0043) and 33% (ORIVW = 1.33, 95% CI 1.12; 1.58), respectively, in comparison with non-GERD cases. In addition, neither heterogeneity nor pleiotropy was found in the study. This study also found that gene expression was higher in the central nervous system and brain tissue than in other normal tissues.

CONCLUSIONS

This study provided evidence that people who developed GERD had a higher risk of developing COPD, bronchitis, pneumonia, lung cancer and pulmonary embolism. Our research suggests physicians to give effective treatments for GERD on respiratory diseases. By exploring the gene expression, our study may also help to reveal the role played by the central nervous system and brain tissue in developing respiratory diseases caused by GERD.

Association of Barrett's esophagus with obstructive sleep apnea syndrome: a bidirectional analysis of Mendelian randomization

Background

Observational studies have reported associations between Barrett's esophagus (BE) and obstructive sleep apnea syndrome (OSAS), but the causal relationship remained unclear due to potential confounding biases. Our study aimed to elucidate this causal relationship by deploying a two-sample Mendelian randomization (MR) methodology.

Methods

Instrumental variables (IVs) for Barrett's esophagus were obtained from a public database that comprised 13,358 cases and 43,071 controls. To investigate OSAS, we utilized summary statistics from a comprehensive genome-wide association study (GWAS) encompassing 38,998 cases of OSAS and 336,659 controls. Our MR analyses adopted multiple techniques, including inverse variance weighted (IVW), weighted median, weighted mode, MR-Egger, and simple mode.

Results

The IVW analysis established a causal relationship between Barrett's esophagus and OSAS, with an odds ratio (OR) of 1.19 and a 95% confidence interval (CI) of 1.11-1.28 (p = 8.88E-07). Furthermore, OSAS was identified as a contributing factor to the onset of Barrett's esophagus, with an OR of 1.44 and a 95% CI of 1.33-1.57 (p = 7.74E-19). Notably, the MR-Egger intercept test found no evidence of directional pleiotropy (p > 0.05).

Conclusion

This study identifies a potential association between BE and an increased occurrence of OSAS, as well as the reverse relationship. These insights could influence future screening protocols and prevention strategies for both conditions.

Mendelian randomization analysis suggests no causal influence of gastroesophageal reflux disease on the susceptibility and prognosis of idiopathic pulmonary fibrosis

BACKGROUND

The relationship between gastroesophageal reflux disease (GERD) and the susceptibility as well as the prognosis of idiopathic pulmonary fibrosis (IPF) has been previously suggested, with the potential confounding factor of smoking not adequately addressed. In light of this, we conducted a Mendelian randomization (MR) study to investigate the causal effects of GERD on the susceptibility and prognosis of IPF while excluding smoking.

METHODS

We chose GERD as the exposure variable and employed genome-wide association data to examine its association with susceptibility, forced vital capacity (FVC), diffusing capacity of the lung for carbon monoxide (DLco), and transplant-free survival (TFS) in patients with IPF as the outcome variables. MR analyses were performed using the inverse variance weighted (IVW) method, and sensitivity analyses were conducted using the MR-PRESSO outlier test, Cochran's Q test, MR-Egger intercept test, and leave-one-out sensitivity analysis. Additionally, to mitigate the potential effects of smoking on our MR estimates, we conducted a multivariable MR (MVMR) analysis by adjusting for smoking.

RESULTS

The univariable MR analysis demonstrated no causal effect of GERD on FVC (βIVW = 26.63, SE = 48.23, P = 0.581), DLco (βIVW = 0.12, SE = 0.12, P = 0.319), and TFS (HRIVW = 0.87, 95% CI = 0.56 to 1.35, P = 0.533) in patients with IPF. Furthermore, sensitivity analysis revealed no evidence of heterogeneity, horizontal pleiotropy, or outlier single nucleotide polymorphisms. The MVMR analysis showed no causal effect of GERD on susceptibility to IPF after adjusting for smoking (ORIVW = 1.30, 95% CI = 0.93 to 1.68, P = 0.071). These findings were consistent in the replication cohort.

CONCLUSIONS

The link between GERD and its potential impact on susceptibility to IPF may not be of a direct causal nature and could be influenced by factors such as smoking. Our findings did not reveal any evidence of a causal relationship between GERD and the FVC, DLco, and TFS of patients with IPF.

Evaluating the causal relationship between human blood metabolites and gastroesophageal reflux disease

BACKGROUND

Gastroesophageal reflux disease (GERD) affects approximately 13% of the global population. However, the pathogenesis of GERD has not been fully elucidated. The development of metabolomics as a branch of systems biology in recent years has opened up new avenues for the investigation of disease processes. As a powerful statistical tool, Mendelian randomization (MR) is widely used to explore the causal relationship between exposure and outcome.

AIM

To analyze of the relationship between 486 blood metabolites and GERD.

METHODS

Two-sample MR analysis was used to assess the causal relationship between blood metabolites and GERD. A genome-wide association study (GWAS) of 486 metabolites was the exposure, and two different GWAS datasets of GERD were used as endpoints for the base analysis and replication and meta-analysis. Bonferroni correction is used to determine causal correlation features (P < 1.03 × 10-4). The results were subjected to sensitivity analysis to assess heterogeneity and pleiotropy. Using the MR Steiger filtration method to detect whether there is a reverse causal relationship between metabolites and GERD. In addition, metabolic pathway analysis was conducted using the online database based MetaboAnalyst 5.0 software.

RESULTS

In MR analysis, four blood metabolites are negatively correlated with GERD: Levulinate (4-oxovalerate), stearate (18:0), adrenate (22:4n6) and p-acetamidophenylglucuronide. However, we also found a positive correlation between four blood metabolites and GERD: Kynurenine, 1-linoleoylglycerophosphoethanolamine, butyrylcarnitine and guanosine. And bonferroni correction showed that butyrylcarnitine (odd ratio 1.10, 95% confidence interval: 1.05-1.16, P = 7.71 × 10-5) was the most reliable causal metabolite. In addition, one significant pathways, the "glycerophospholipid metabolism" pathway, can be involved in the pathogenesis of GERD.

CONCLUSION

Our study found through the integration of genomics and metabolomics that butyrylcarnitine may be a potential biomarker for GERD, which will help further elucidate the pathogenesis of GERD and better guide its treatment. At the same time, this also contributes to early screening and prevention of GERD. However, the results of this study require further confirmation from both basic and clinical real-world studies.

Association Between Anxiety/Depression and Gastroesophageal Reflux: A Systematic Review and Meta-Analysis

INTRODUCTION

An association between gastroesophageal reflux disease (GERD) and common psychiatric conditions, most notably anxiety and depression, has been reported. However, the magnitude of this association is poorly understood. Therefore, we aimed to systematically assess this issue.

METHODS

We comprehensively searched multiple bibliographic databases (Embase, PubMed, Scopus, and Web of Science) from inception to May 15, 2023. We retrieved observational studies that reported the prevalence of anxiety and/or depressive symptoms diagnosed by validated questionnaires in ≥100 adults (aged 18 years or older) with GERD. We also included cohort studies that explored the risk of incident GERD in subjects with anxiety/depression vice versa scenario. Finally, we included Mendelian randomization studies that assessed the cause-and-effect relationship between anxiety/depression and GERD. The extracted data were combined using a random-effects model.

RESULTS

In total, 36 eligible studies were included. The pooled prevalences of anxiety and depressive symptoms were 34.4% (95% confidence interval [CI] 24.7-44.2; I2 = 99.4%) and 24.2% (95% CI 19.9-28.5; I2 = 98.8%) in subjects with GERD based on 30 studies, respectively. Both anxiety and depressive symptoms were more common in subjects with GERD compared with those in healthy controls (odds ratio = 4.46 [95% CI 1.94-10.25] and odds ratio = 2.56 [95% CI 1.11-5.87], respectively). According to 3 cohort studies, subjects with GERD were at an increased risk of developing anxiety/depression and vice versa. Finally, 3 Mendelian randomization studies showed that genetic liability to these mood disorders is linked to an increased risk of developing GERD and vice versa.

DISCUSSION

Up to 1 in 3 subjects with GERD experience anxiety and depression. There is likely a bidirectional causal relationship between anxiety/depression and GERD.

Unraveling the Complex Relationship Between Gastroesophageal Reflux Disease, Lifestyle Factors, and Interstitial Lung Disease: Insights From Two-Sample Mendelian Randomization Analyses

Background Although the cause of interstitial lung disease (ILD) remains uncertain, it is believed to be a combination of genetic and non-inherited factors, such as smoking and diet. This research aims to evaluate the impact of gastroesophageal reflux disease (GERD) and other modifiable risk factors on the likelihood of developing ILD by utilizing two-sample Mendelian randomization. Methodology The research utilized publicly accessible single-nucleotide polymorphisms (SNPs) that were deemed significant on a genome-wide scale. These SNPs were chosen from prior studies conducted by various consortia. The study examined GERD and a wide range of smoking habits, including the age at which individuals started smoking, the intensity of their smoking, and whether their mothers smoked. Additionally, the study considered other relevant risk factors such as key dietary factors, coffee consumption, body mass index (BMI), and physical activity. The study focused on self-reported ILD as its outcome measure. The genetic information for ILD was sourced from the FinnGen and UK Biobank (UKB) cohorts. Results The study encompassed a wide range of sample sizes, varying from 64,949 to 632,802, for each risk factor collected from multiple consortia. In total, 593 SNPs were included for all risk factors. The findings revealed significant associations between genetically estimated GERD, dietary factors, BMI, and the risk of ILD within the FinnGen consortium. The odds ratios (ORs) indicated an increase in the risk of ILD per unit of GERD (OR = 1.17, p = 0.001), smoking initiation (OR = 1.10, p < 0.05), BMI (OR = 1.15, p = 0.006), and low-density lipoprotein (LDL) (OR = 1.10, p = 0.02). On the other hand, there was a decrease in the risk of ILD per unit increase in coffee intake (OR = 0.64, p = 0.01) and physical activity (OR = 0.79, p=0.03). Additionally, the results demonstrated a significant association between genetically estimated GERD (OR = 1.01, p < 0.05), coffee intake (OR = 1.14, p=0.03), and high-density lipoproteins (HDL) (OR = 1.01, p=0.04) and increased risk of ILD specifically within the UKB. Conclusions This research indicates that the development of ILDs may be causally associated with GERD and various factors such as coffee intake, smoking, BMI, physical activity, LDL, and HDL These results hold great importance in terms of devising effective strategies for the treatment and prevention of ILDs.

Causal association of gastroesophageal reflux disease with obstructive sleep apnea and sleep-related phenotypes: a bidirectional two-sample Mendelian randomization study

Background

The interactions and associations between obstructive sleep apnea (OSA), sleep-related phenotypes (SRPs), and gastroesophageal reflux disease (GERD) are complex, thus it is hard to explore the effect and direction of causalities.

Study objectives

A bidirectional Mendelian randomization (MR) study was performed to explore causal associations of GERD with OSA and SRPs (including insomnia, morningness, sleep duration, ease of getting up, daytime napping, daytime dozing, and snoring).

Methods

First, we gathered summary statistics from publicly available databases. Subsequently, we identified single-nucleotide polymorphisms without strong linkage (r2 ≤ 0.001) by referencing relevant genome-wide association studies that met genome-wide significance criteria. Our primary analysis relied on inverse variance weighted to estimate the causal relationship. To ensure the validity of our findings, we also conducted several sensitivity analyses. These included MR Pleiotropy RESidual Sum and Outlier to detect and correct for potential pleiotropic effects, MR-Egger to assess directional pleiotropy, and weighted median analysis to further evaluate heterogeneity and pleiotropy. For the initial MR analysis, when causality was indicated by the results, instrumental variables that were significantly linked to the aforementioned confounding factors were removed. We will re-analyze the data after excluding outcome-related single nucleotide polymorphisms to confirm that the results are still consistent with the previous results.

Results

GERD was found to increase the risk of OSA (OR = 1.53, 95% CI = 1.37-1.70, p = 5.3 × 10-15), insomnia (OR = 1.14, 95% CI = 1.10-1.19, p = 1.3 × 10-10), snoring (OR = 1.09, 95% CI = 1.04-1.13, p = 6.3 × 10-5) and less sleep duration (OR = 0.94, 95% CI = 0.91-0.97, p = 3.7 × 10-4). According to the reverse-direction analysis, there is an elevated risk of GERD associated with OSA (OR = 1.07, 95% CI = 1.02-1.12, p = 0.005), insomnia (OR = 1.95, 95% CI = 1.60-2.37, p = 1.92 × 10-11) and snoring (OR = 1.74, 95% CI = 1.37-2.21, p = 4.4 × 10-6).

Conclusion

Genetic susceptibility to GERD can elevate the likelihood of experiencing insomnia, snoring, and OSA, in addition to diminishing sleep duration. Conversely, a reverse MR analysis indicates that ameliorating any one of insomnia, snoring, or OSA can mitigate the risk of developing GERD.

Gut microbiota and common gastrointestinal diseases: a bidirectional two-sample Mendelian randomized study

Background

Several recent studies have shown an association between gut microbiota and gastrointestinal diseases. However, the causal relationship between gut microbiota and gastrointestinal disorders is unclear.

Methods

We assessed causal relationships between gut microbiota and eight common gastrointestinal diseases using Mendelian randomization (MR) analyses. IVW results were considered primary results. Cochrane's Q and MR-Egger tests were used to test for heterogeneity and pleiotropy. Leave-one-out was used to test the stability of the MR results, and Bonferroni correction was used to test the strength of the causal relationship between exposure and outcome.

Results

MR analyses of 196 gut microbiota and eight common gastrointestinal disease phenotypes showed 62 flora and common gastrointestinal diseases with potential causal relationships. Among these potential causal relationships, after the Bonferroni-corrected test, significant causal relationships remained between Genus Oxalobacter and CD (OR = 1.29, 95% CI: 1.13-1.48, p = 2.5 × 10-4, q = 4.20 × 10-4), and between Family Clostridiaceae1 and IBS (OR = 0.9967, 95% CI: 0.9944-0.9991, p = 1.3 × 10-3, q = 1.56 × 10-3). Cochrane's Q-test showed no significant heterogeneity among the various single nucleotide polymorphisms (SNPs). In addition, no significant level of pleiotropy was found according to the MR-Egger.

Conclusion

This study provides new insights into the mechanisms of gut microbiota-mediated gastrointestinal disorders and some guidance for targeting specific gut microbiota for treating gastrointestinal disorders.

Common gastrointestinal diseases and chronic obstructive pulmonary disease risk: a bidirectional Mendelian randomization analysis

Background: Observational studies suggest an association between gastrointestinal diseases and chronic obstructive pulmonary disease (COPD), but the causal relationship remains unclear. Methods: We conducted bidirectional Mendelian randomization (MR) analysis using summary data from genome-wide association study (GWAS) to explore the causal relationship between common gastrointestinal diseases and COPD. Gastrointestinal diseases included gastroesophageal reflux disease (GERD), peptic ulcer disease (PUD), irritable bowel syndrome (IBS), Crohn's disease (CD), ulcerative colitis (UC), functional dyspepsia (FD), non-infectious gastroenteritis (NGE), and constipation (CP). Significant MR analysis results were replicated in the COPD validation cohort. Results: Bidirectional MR analysis supported a bidirectional causal relationship between GERD and COPD, and COPD was also found to increase the risk of IBS and CP. Our study also provided evidence for a bidirectional causal relationship between PUD and COPD, although the strength of evidence may be insufficient. Furthermore, we provided evidence that there is no causal association between CD, UC, FD, NGE, and COPD. Conclusion: This study offers some evidence to clarify the causal relationship between common gastrointestinal diseases and COPD. Further research is needed to understand the underlying mechanisms of these associations.

Causal relationship between gastro-esophageal reflux disease and risk of lung cancer: insights from multivariable Mendelian randomization and mediation analysis

AIM

A recent study has reported that anti-reflux surgery reduced the risk of lung cancer. However, the exact causal association between gastro-esophageal reflux disease (GORD) and lung cancer remains obscure. Therefore, we conducted a multivariable and network Mendelian randomization (MR) study to explore this potential association and mediation effect.

METHODS

Independent single nucleotide polymorphisms (SNPs) strongly associated with GORD were selected as instrumental variables (IVs) from the corresponding genome-wide association studies (GWAS). The summary statistics were obtained from the largest GORD GWAS meta-analysis of 367 441 (78 707 cases) European individuals, and the summary statistics of lung cancer and pathological subtypes came from International Lung Cancer Consortium (ILCCO) and FinnGen databases. Univariable and multivariable MR analyses were performed to investigate and verify the causal relationship between genetically predicted GORD and lung cancer. Network MR analysis was conducted to reveal the mediating role of GORD between smoking initiation and lung cancer.

RESULTS

The univariable MR analysis demonstrated that GORD was associated with an increased risk of total lung cancer in both ILCCO [inverse variance weighted (IVW): odds ratio (OR) = 1.37, 95% confidence interval (CI) 1.16-1.62, P = 1.70E-04] and FinnGen database (IVW: OR = 1.25, 95% confidence interval CI 1.03-1.52, P = 2.27E-02). The consistent results were observed after adjusting the potential confounders [smoking traits, body mass index (BMI) and type 2 diabetes] in multivariable MR analyses. In subtype analyses, GORD was associated with lung adenocarcinoma (IVW: OR = 1.27, 95% CI 1.02-1.59, P = 3.48E-02) and lung squamous cell carcinomas (IVW: OR = 1.50, 95% CI 1.22-1.86, P = 1.52E-04). Moreover, GORD mediated 32.43% (95% CI 14.18-49.82%) and 25.00% (95% CI 3.13-50.00%) of the smoking initiation effects on lung cancer risk in the ILCCO and FinnGen databases, respectively.

CONCLUSION

This study provides credible evidence that genetically predicted GORD was significantly associated with an increased risk of total lung cancer, lung adenocarcinoma and lung squamous cell carcinomas. Furthermore, our results suggest GORD is involved in the mechanism of smoking initiation-induced lung cancer.

Mendelian randomization study of gastroesophageal reflux disease and major depression

This study systematically investigated the causal relationship between gastroesophageal reflux disease (GERD) and major depression (MD). Single-nucleotide polymorphisms (SNPs) associated with disorders of interest were screened via the genome-wide association study (GWAS) enrolling individuals of European descent. Summary-level data for GERD and MD were extracted from the UK Biobank. The inverse-variance-weighted (IVW) method was utilized as the primary analysis. Sensitivity analyses were performed using the MR-Egger method, the Maximum likelihood method, the MR-pleiotropy residual sum outlier (MR-PRESSO) method, and MR-robust adjusted profile score (MR-RAPS) method. MR-Egger regression, heterogeneity tests, pleiotropy tests, and leave-one-out tests were also performed to analyze sensitivity. The MR Steiger test was used to verify the directionality of the exposure to the outcome. An available website tool (https://shiny.cnsgenomics.com/mRnd/) was used to calculate the statistical power of MR analysis. Meta-analysis was applied to test MD's average genetically predicted effect on GERD. Our MR study showed a bidirectional causal association between MD and GERD. Regarding MD to GERD, there was a positive association between them; the ORs were 1.500 (95% CI = 1.320-1.704; P = 4.91E-10) and 2.058 (95% CI = 1.868-2.267; P = 2.20E-48) in the IVW method, respectively. In addition, the meta-analysis also showed a strong positive causal association between MD and GERD. When exposure and outcome were reversed, genetic predisposition to GERD was significantly associated with the overall Risk of advanced MD (ieu-a-1187, OR = 1.982, 95% CI = 1.694-2.319, P = 1.41E-17; ieu-b-102, OR = 1.612, 95% CI = 1.530-2.700, P = 1.15E-70). Our study provides 100% power to detect the causal effect of MD on GERD and vice versa. Genetically predicted MD was positively associated with higher GERD risk, and vice versa. Our study reminds clinicians to pay attention to screening for GERD when diagnosing and treating MD and vice versa. Moreover, there may be positive feedback between MD and GERD when treating and preventing one disorder may benefit the treatment and prevention of the other.