Genetic estimation of correlations and causalities between multifaceted modifiable factors and gastro-oesophageal reflux disease.

Gastro-oesophageal reflux disease (GORD) is a common gastrointestinal dysfunction that significantly affects the quality of daily life, and health interventions are challenging to prevent the risk of GORD. In this study, we used Mendelian randomization framework to genetically determine the causal associations between multifaceted modifiable factors and the risk of GORD. Sixty-six exposures with available instrumental variables (IVs) across 6 modifiable pathways were included in the univariable MR analysis (UVMR). Summary-level genome-wide association studies (GWAS) datasets for GORD were retrieved from the Neale Lab (GORD Neale , Ncases = 29975, Ncontrols = 390556) and FinnGen (GORD Finn , Ncases = 13141, Ncontrols = 89695). Using the METAL software, meta-analysis for single nucleotide polymorphisms (SNPs) from GORD Neale and GORD Finn was conducted with an inverse variance weighted (IVW) fixed-effect model. Moreover, we leveraged partition around medoids (PAM) clustering algorithm to cluster genetic correlation subtypes, whose hub exposures were conditioned for multivariable MR (MVMR) analyses. P-values were adjusted with Bonferroni multiple comparisons. Significant causal associations were identified between 26 exposures (15 risk exposures and 11 protective exposures) and the risk of GORD. Among them, 13 risk exposures [lifetime smoking, cigarette consumption, insomnia, short sleep, leisure sedentary behavior (TV watching), body mass index (BMI), body fat percentage, whole body fat mass, visceral adipose tissue, waist circumference, hip circumference, major depressive disorder, and anxious feeling], and 10 protective exposures (leisure sedentary behavior (computer use), sitting height, hand grip strength (left and right), birth weight, life satisfaction, positive affect, income, educational attainment, and intelligence) showed novel significant causal associations with the risk of GORD. Moreover, 13 exposures still demonstrated independent associations with the risk of GORD following MVMR analyses conditioned for hub exposures (educational attainment, smoking initiation and BMI). In addition, 12 exposures showed suggestive causal associations with the risk of GORD. This study systematically elucidated the modifiable factors causally associated with the risk of GORD from multifaceted perspectives, which provided implications for prevention and treatment of GORD.

Sun Y ，Cao X ，Cao D ，Cui Y ，Su K ，Jia Z ，Wu Y ，Jiang J ... -  《Frontiers in Nutrition》

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

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. 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. 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. 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.

Liu Y ，Lai H ，Zhang R ，Xia L ，Liu L ... -  《-》

Genetic evidence that higher central adiposity causes gastro-oesophageal reflux disease: a Mendelian randomization study.

Gastro-oesophageal reflux disease (GORD) is associated with multiple risk factors but determining causality is difficult. We used a genetic approach [Mendelian randomization (MR)] to identify potential causal modifiable risk factors for GORD. We used data from 451 097 European participants in the UK Biobank and defined GORD using hospital-defined ICD10 and OPCS4 codes and self-report data (N = 41 024 GORD cases). We tested observational and MR-based associations between GORD and four adiposity measures [body mass index (BMI), waist-hip ratio (WHR), a metabolically favourable higher body-fat percentage and waist circumference], smoking status, smoking frequency and caffeine consumption. Observationally, all adiposity measures were associated with higher odds of GORD. Ever and current smoking were associated with higher odds of GORD. Coffee consumption was associated with lower odds of GORD but, among coffee drinkers, more caffeinated-coffee consumption was associated with higher odds of GORD. Using MR, we provide strong evidence that higher WHR and higher WHR adjusted for BMI lead to GORD. There was weak evidence that higher BMI, body-fat percentage, coffee drinking or smoking caused GORD, but only the observational effects for BMI and body-fat percentage could be excluded. This MR estimated effect for WHR equates to a 1.23-fold higher odds of GORD per 5-cm increase in waist circumference. These results provide strong evidence that a higher waist-hip ratio leads to GORD. Our study suggests that central fat distribution is crucial in causing GORD rather than overall weight.

Green HD ，Beaumont RN ，Wood AR ，Hamilton B ，Jones SE ，Goodhand JR ，Kennedy NA ，Ahmad T ，Yaghootkar H ，Weedon MN ，Frayling TM ，Tyrrell J ... -  《-》

Evaluating the causal relationship between five modifiable factors and the risk of spinal stenosis: a multivariable Mendelian randomization analysis.

Spinal stenosis is a neurological disorder related to the compression of the spinal cord or nerve roots, and its incidence increases yearly. We aimed to use Mendelian randomization (MR) to investigate the causal relationship between several modifiable risk factors and the risk of spinal stenosis. We obtained genome-wide association study summary data of large-sample projects (more than 100,000 individuals) from public databases. The data were associated with traits, including years of schooling (educational attainment) from the IEU OpenGWAS Project, smoking behavior (never vs. initiation) from the IEU OpenGWAS Project, body mass index (BMI) from the UK Biobank, length of mobile phone use from the UK Biobank, time spent watching television (TV) from the UK Biobank, and spinal stenosis from FinnGen biobank. Spinal stenosis was used as the outcome, whereas the other four traits were used as exposures. Inverse variance weighted (IVW) regressions were used as a primary to estimate the causal-effect size. Several sensitive analyses (including consistency, heterogenicity, and pleiotropy analyses) were conducted to test the stability and reliability of causal estimates. Univariable MR analyses showed that genetically predicted higher educational attainment (IVW; odds ratio (OR) = 0.606; 95% confidence interval (CI): 0.507-0.724; P = 3.37 × 10-8) and never smoking (IVW; OR = 1.388; 95% CI [1.135-1.697]; P = 0.001) were negatively correlated with the risk of spinal stenosis. Meanwhile, a higher BMI (IVW; OR = 1.569; 95% CI [1.403-1.754]; P = 2.35 × 10-8), longer time spent using a mobile phone (IVW; OR = 1.895; 95% CI [1.306-2.750]; P = 0.001), and watching TV (IVW; OR = 1.776; 95% CI [1.245-2.532]; P = 0.002) were positively associated with the risk of spinal stenosis. Multivariable MR analysis indicated that educational attainment (IVW; OR = 0.670; 95% CI [0.465-0.967]; P = 0.032) and BMI (IVW; OR = 1.365; 95% CI [1.179-1.580]; P = 3.12 × 10-5) were independently causally related to the risk of spinal stenosis. Our findings supported the potential causal associations of the five factors (educational attainment, smoking behavior, BMI, length of mobile phone use, and watching TV) with the risk for spinal stenosis. While replication studies are essential, these findings may provide a new perspective on prevention and intervention strategies directed toward spinal stenosis.

Wan B ，Ma N ，Lu W 《PeerJ》

Modifiable risk factors that mediate the effect of educational attainment on the risk of stroke: a network Mendelian randomization study.

Stroke is a common cerebrovascular disease with great danger to public health. Educational inequality is a universal issue that influences populations' stroke risk. This study aimed to investigate the causal relationship between education and stroke risk and the contributions of effects mediated by four modifiable factors. Public large-scale genome-wide association study (GWAS) summary data associated with educational attainment, hypertensive diseases, body mass index (BMI), smoking behavior, time spent on watching the television (TV), and stroke were obtained from European ancestry. The data were used to investigate the causal relationship among educational attainment, hypertensive disease, BMI, smoking, watching TV, and stroke risk. Inverse variance weighted (IVW) method was used as a primary algorithm for estimating causal direction and effect size in univariable and multivariable Mendelian randomization (MR) analyses. Higher educational attainment was a causal protective factor, while hypertensive diseases, higher BMI, smoking, and longer time spent on watching the TV were all causal risk factors for the risk of stroke. Hypertensive disease, BMI, smoking, and watching TV were all mediators for linking the causal relationship between educational attainment and stroke risk. Hypertensive disease, BMI, smoking, and watching TV explained 47.35%, 24.74%, 15.72%, and 2.29% of the variance in educational attainment's effect on stroke risk, respectively. The explained proportion reached 69.32% after integrating the four factors. These findings support the causal effect of educational attainment on the risk of stroke, with a substantial proportion mediated by modifiable risk factors. Interventions on these modifiable factors would lead to substantial reductions in stroke cases attributable to educational inequality.

Wan B ，Ma N ，Zhou Z ，Lu W ... -  《Molecular Brain》