Bidirectional Two-sample Mendelian Randomization Research Articles

Plasma Proteomes and Genome-Wide Association Data for Causal Protein Identification in Stroke.

Plasma proteins are promising biomarkers and potential drug targets for stroke. This study aimed to explore whether there is a causal relationship between plasma proteins and subtypes of stroke using a Mendelian randomization (MR) approach. A two-sample bidirectional Mendelian randomization approach was employed to investigate the causal link between plasma proteins and stroke. Data on plasma proteins were obtained from three studies, including INTERVAL, and pooled stroke information was sourced from the MEGASTROKE consortium and the UK Biobank dataset, covering four subtypes of stroke. MR analyses were primarily conducted using inverse variance weighting, and sensitivity analyses were also performed. Finally, potential reverse causality was assessed using bidirectional MR. We identified two proteins causally associated with stroke: one as a potential therapeutic target and another as a protective factor. CXCL8 was found to be positively associated with the risk of developing large-artery atherosclerotic (LAA) stroke (OR, 1.005; 95% CI 1.001 to 1.010; p = 0.022), whereas TNFRSF11b was negatively correlated with the risk of developing LAA stroke (OR, 0.937; 95% CI 0.892 to 0.984; p = 0.010), independently of other stroke subtypes. Reverse bivariate analysis did not indicate that ischemic stroke was causally associated with CXCL8 and TNFRSF11b. There is a causal relationship between CXCL8 and TNFRSF11b with LAA stroke, independent of other subtypes. This study offers a new perspective on the genetics of stroke.

Circulating inflammatory cytokines and the risk of sepsis: a bidirectional mendelian randomization analysis

BackgroundSepsis is a life-threatening condition that is characterized by multiorgan dysfunction and caused by dysregulated cytokine networks, which are closely associated with sepsis progression and outcomes. However, currently available treatment strategies that target cytokines have failed. Thus, this study aimed to investigate the interplay between genetically predicted circulating concentrations of cytokines and the outcomes of sepsis and to identify potential targets for sepsis treatment.MethodsData related to 35 circulating cytokines in 31,112 individuals (including 11,643 patients with sepsis) were included in genome-wide association studies (GWASs) from the UK Biobank and FinnGen consortia. A bidirectional two-sample Mendelian randomization (MR) analysis was performed using single nucleotide polymorphisms (SNPs) to evaluate the causal effects of circulating cytokines on sepsis outcomes and other cytokines.ResultsA total of 35 inflammatory cytokine genes were identified in the GWASs, and 11 cytokines, including Interleukin-1 receptor antagonist (IL-1ra), macrophage inflammatory protein 1 (MIP1α), IL-16, et al., were associated with sepsis outcome pairs according to the selection criteria of the cis-pQTL instrument. Multiple MR methods verified that genetically predicted high circulating levels of IL-1ra or MIP1α were negatively correlated with genetic susceptibility to risk of sepsis, including sepsis (28-day mortality), septicaemia, streptococcal and pneumonia-derived septicaemia (P ≤ 0.01). Furthermore, genetic susceptibility of sepsis outcomes except sepsis (28-day mortality) markedly associated with the circulating levels of five cytokines, including active plasminogen activator inhibitor (PAI), interleukin 7 (IL-7), tumour necrosis factor alpha (TNF-α), beta nerve growth factor (NGF-β), hepatic growth factor (HGF) (P < 0.05). Finally, we observed that the causal interaction network between MIP1α or IL-1ra and other cytokines (P < 0.05).ConclusionsThis comprehensive MR analysis provides insights into the potential causal mechanisms that link key cytokines, particularly MIP1α, with risk of sepsis, and the findings suggest that targeting MIP1α may be a potential strategy for preventing sepsis.

Unraveling the association between gut microbiota and chemotherapy efficacy: a two-sample Mendelian randomization study.

Emerging evidence has underscored the complex link between gut microbiota and chemotherapy efficacy; however, establishing causality remains elusive due to confounding factors. This study, leveraging bidirectional two-sample Mendelian randomization (MR) analyses, explores the casual relationship between gut microbiota and chemotherapy efficacy. Utilizing genome-wide association study (GWAS) data from the MiBioGen consortium for gut microbiota and IEU Open GWAS for chemotherapy efficacy, we employed genetic variants as instrumental variables (IVs). The inverse variance weighted (IVW) method, weighted median estimator (WME), and MR-Egger regression method were applied, with sensitivity analyses ensuring robustness. Furthermore, we conducted reverse MR analyses between chemotherapy efficacy and identified significant gut microbial taxa. The results indicated that genus Butyricicoccus (OR = 3.7908, 95% CI: 1.4464-9.9350, P = 0.01), Dorea (OR = 3.3295, 95% CI: 1.2794-8.6643, P = 0.01), Hungatella (OR = 2.6284, 95% CI: 1.0548-6.5498, P = 0.04), and Turicibacter (OR = 2.5694, 95% CI: 1.0392-6.3526, P = 0.04) were positively associated with chemotherapy efficacy using the IVW method. Conversely, family Porphyromonadaceae (OR = 0.2283, 95% CI: 0.0699-0.7461, P = 0.01) and genus Eggerthella (OR = 0.4953, 95% CI: 0.2443-1.0043, P = 0.05) exhibited negative associations. WME demonstrated consistent results with IVW method only for genus Eggerthella (OR = 0.3343, 95% CI: 0.1298-0.8610, P = 0.02). No significant heterogeneity or horizontal pleiotropy was observed. Reverse MR analyses revealed no significant causal effect of chemotherapy on identified gut microbiota. This study sheds light on the intricate relationship between gut microbiota, with a particular emphasis on the genus Eggerthella, and chemotherapy efficacy, offering valuable insights for refining cancer treatment strategies.IMPORTANCEGlobal advancements in cancer treatment, particularly in chemotherapy, have notably decreased mortality rates in recent years. However, the correlation between gut microbiota and chemotherapy efficacy remains elusive. Our study, emphasizing the role of genus Eggerthella, represented a crucial advance in elucidating this intricate interplay. The identified associations offer potential therapeutic targets, contributing to global efforts for enhanced treatment precision and improved patient outcomes. Furthermore, our findings hold promise for personalized therapeutic interventions, shaping improved strategies in the ever-evolving landscape of cancer treatment.

Causal roles of skin microbiota in skin cancers suggested by genetic study

BackgroundThere is evidence from observational studies that skin microbiota is linked to skin cancers. Nevertheless, the causal association between skin microbiota and skin cancers is yet to be fully clarified.MethodsA bidirectional two-sample Mendelian randomization (MR) was performed to determine the causal relationship between skin microbiota and skin cancers. A total of 294 skin microbial taxa were identified from the first genome-wide association study across three skin microenvironments of two German population cohorts. Summary data of three skin cancers (malignant melanoma, squamous cell carcinoma, and basal cell carcinoma) were obtained from the FinnGen consortium. Moreover, sensitivity analysis examined horizontal pleiotropy and heterogeneity, and microenvironment-based meta-analysis confirmed the reliability of the results.ResultsWe identified 65 nominal causalities and 5 strong causal associations between skin microbiota and skin cancers. Among them, the class Bacilli revealed a bidirectional positive relationship with malignant melanoma. The class Betaproteobacteria and class Gammaproteobacteria demonstrated a causal association with an elevated risk of malignant melanoma and basal cell carcinoma, respectively. In the reverse MR analysis, malignant melanoma was associated with a lower abundance of phylum Bacteroidetes. There were no indications of significant heterogeneity in instrumental variables or evidence of horizontal pleiotropy.ConclusionOur MR analysis indicated bidirectional causal associations between skin microbiota and skin cancers, and had the potential to offer novel perspectives on the mechanistic of microbiota-facilitated carcinogenesis.

Genetic insights into the gut microbiota and risk of psoriasis: a bidirectional mendelian randomization study

BackgroundGrowing evidence indicates a potential association between the gut microbiome and psoriasis. Nevertheless, the precise nature of these associations and whether they constitute causal relationships remain unclear.MethodsA rigorous bidirectional two-sample Mendelian randomization study was undertaken to establish a putative causal link between gut microbiota and psoriasis. We drew upon publicly available datasets containing summary statistics from GWAS to accomplish this. Utilizing various analytical techniques, including inverse variance weighting, MR-Egger, weighted median, weighted model, and MR-PRESSO, we sought to validate the putative causal association between gut microbiota and psoriasis. A reverse Mendelian randomization analysis was conducted to further investigate the relationship.ResultsAfter conducting a forward Mendelian randomization analysis, a causal relationship was established between 19 gut microbiota and psoriasis. Furthermore, the reverse MR study revealed causality between psoriasis and 13 gut microbiota. Notably, no substantial heterogeneity of instrumental variables or horizontal pleiotropy was observed.ConclusionThis research suggests a potential genetic association and causal nexus between gut microorganisms and psoriasis, indicating potential implications for the clinical management and therapy of psoriasis. Additional observational studies with a larger population sample size and animal model experiments are imperative to fully elucidate this association’s underlying mechanisms.

Bidirectional two-sample Mendelian randomization analysis identifies causal associations between migraine and five psychiatric disorders

BackgroundThe question of whether a correlation exists between migraine and five psychiatric disorders, including posttraumatic stress disorder (PTSD), major depressive disorder (MDD), anorexia nervosa (AN), bipolar disorder (BIP), and schizophrenia (SCZ), remains a matter of controversy. Hence, this research aims to investigate whether there is a possible association between migraine and five psychiatric disorders.MethodsWe performed a bidirectional 2-sample Mendelian randomization (MR) analysis to assess the causality between migraine and five psychiatric disorders. Genetic associations of PTSD, MDD, AN, BIP, and SCZ were obtained from the Psychiatric Genomics Consortium (PGC) database and genetic associations of migraine with aura and migraine without aura were obtained from the FinnGen dataset. We used the inverse-variance weighted (IVW), weighted median, weighted mode, MR Pleiotropy RESidual Sum and Outlier (MR-PRESSO), and MR Egger regression methods to evaluate the association of genetically predicted exposure with the risk of outcome.ResultsMR demonstrated that MDD was associated with a high risk of migraine without aura (OR = 1.930578, 95% confidence interview (CI): 1.224510, 3.043550, p &amp;lt; 0.05), but BIP was related to a low risk of migraine without aura (OR = 0.758650, 95%CI: 0.639601, 0.899858, p &amp;lt; 0.05). According to the results of reverse MR, migraine with aura was associated with a high risk of BIP (OR = 1.019100, 95%CI: 1.002538, 1.035935, p &amp;lt; 0.05), and migraine without aura was associated with an increased risk of AN (OR = 1.055634, 95%CI: 1.023859, 1.088394, p &amp;lt; 0.05).ConclusionOur results provide evidence of the potential causal association between migraine and some psychiatric disorders. It may contribute to the prevention of migraine and some psychiatric disorders.

Exploring the causal relationships between cholelithiasis, cholecystitis, cholecystectomy, and gastroesophageal reflux disease: A bidirectional two-sample mendelian randomization study.

Biliary disorders and gastroesophageal reflux disease (GERD) frequently coexist. However, precise linkages between these conditions remain to be clarified. Univariable Mendelian randomization (MR), Bayesian weighted MR (BWMR) along with multivariable MR approaches were conducted using genetic instruments to evaluate the causality involving biliary disorders and GERD. Furthermore, an investigation was conducted on the potential mediating roles of biliary disorders (or GERD), on the linkage involving body mass index (BMI) and GERD (or biliary disorders). Univariable MR analyses revealed significant causal effects of genetically predicted cholelithiasis (odds ratio (OR)=1.04, P=0.0001), cholecystitis (OR=1.06, P=0.0004), and cholecystectomy (OR=2.56, P=1.05×10-6) on GERD. These findings were replicated in the FinnGen cohort and were also confirmed by BWMR and multivariable MR analyses. Additionally, mediation analyses demonstrated that cholelithiasis and cholecystitis acted as partial mediators, linking BMI causally to GERD. Conversely, GERD exhibited causal effect on cholelithiasis (OR=1.52, P=9.17×10-30) and cholecystitis (OR=1.90, P=3.32×10-28), which remained significant after BWMR and multivariable MR analyses. Mediation analyses further revealed significant mediating effect of GERD on how BMI influenced cholelithiasis/cholecystitis. Our study elucidates the bidirectional causal linkages involving cholelithiasis, cholecystitis, cholecystectomy, and GERD. These results highlight the significance of GERD risk assessment in individuals suffering from biliary diseases and vice versa.

Gastroesophageal reflux disease increases the risk of rheumatoid arthritis: a bidirectional two-sample Mendelian randomization study

Rheumatoid arthritis (RA) is a common autoimmune disease, and some observational studies have indicated an association between Gastroesophageal Reflux Disease (GERD) and RA. However, the causal relationship between the two remains uncertain. We used Mendelian randomization (MR) to assess the causal relationship between GERD and RA. Two-sample Mendelian randomization analysis was performed using pooled data from large-scale genome-wide association studies. In addition, we performed multivariate MR analyses to exclude confounding factors between GERD and RA, including smoking quantity, drinking frequency, BMI, depression, and education attainment. The MR results for GERD on RA suggested a causal effect of the genetic susceptibility of GERD on RA (discovery dataset, IVW, odds ratio [OR] = 1.41, 95% confidence interval [CI] 1.22–1.63, p = 2.81 × 10−6; validation dataset, IVW, OR = 1.38, 95% CI 1.23–1.55, P = 1.76 × 10−8). Multivariate MR analysis also supports this result. But the results of the reverse MR analysis did not reveal compelling evidence that RA can increase the risk of developing GERD. Our bidirectional Two-Sample Mendelian randomization analysis and multivariate MR analysis provide support for the causal effect of GERD on RA. This discovery could offer new insights for the prevention and treatment of RA.

Identifying the genetic association between the cerebral cortex and fibromyalgia.

Fibromyalgia (FM) is a central sensitization syndrome that is strongly associated with the cerebral cortex. This study used bidirectional two-sample Mendelian randomization (MR) analysis to investigate the bidirectional causality between FM and the cortical surface area and cortical thickness of 34 brain regions. Inverse variance weighted (IVW) was used as the primary method for this study, and sensitivity analyses further supported the results. The forward MR analysis revealed that genetically determined thinner cortical thickness in the parstriangularis (OR = 0.0567mm, PIVW = 0.0463), caudal middle frontal (OR = 0.0346mm, PIVW = 0.0433), and rostral middle frontal (OR = 0.0285mm, PIVW = 0.0463) was associated with FM. Additionally, a reduced genetically determined cortical surface area in the pericalcarine (OR = 0.9988mm2, PIVW = 0.0085) was associated with an increased risk of FM. Conversely, reverse MR indicated that FM was associated with cortical thickness in the caudal middle frontal region (β = -0.0035mm, PIVW = 0.0265), fusiform region (β = 0.0024mm, SE = 0.0012, PIVW = 0.0440), the cortical surface area in the supramarginal (β = -9.3938mm2, PIVW = 0.0132), and postcentral regions (β = -6.3137mm2, PIVW = 0.0360). Reduced cortical thickness in the caudal middle frontal gyrus is shown to have a significant relationship with FM prevalence in a bidirectional causal analysis.

Revealing an association between HPV and systemic lupus erythematosus: A bidirectional two-sample Mendelian randomization study.

An increasing number of studies have focused on the association between Human papillomavirus (HPV) infection and systemic lupus erythematosus (SLE). However, current evidence is largely based on retrospective studies, which are susceptible to confounding factors and cannot establish causation. A bidirectional two-sample Mendelian randomization (MR) design was used to evaluate the causal relationship between HPV and SLE. Mononucleoside polymers (SNPS) with strong evidence for genome-wide association studies (GWAS) were selected from the HPV exposure dataset and used as an instrumental variable (IV) for this study. For the MR Analysis results, the MR-Egger intercept P test, MR-Presso global test, CochranQ test and leave-one test were used for sensitivity analysis. Based on the evidence of MR Analysis, this study finally determined that there was no causal association between HPV16 and HPV18 and SLE. Possible regulation of HPV infection is not significantly associated with regulation of SLE. These findings provide new insights into the underlying mechanisms of HPV and SLE and need to be validated by further studies.

Exploring causal correlations between blood inflammatory cytokines and low back pain: a Mendelian randomization

PurposeLow back pain (LBP) is a common and recurring public health problem that affects sufferers both physically and mentally and warrants further research. A succession of studies have suggested a plausible role for inflammatory cytokines in the pathogenesis of LBP. To date, there is no conclusive mechanism explaining how inflammatory cytokines affects LBP.MethodsA bidirectional two-sample Mendelian randomization (MR) investigation was undertaken in two stages. The initial phase encompassed 41 inflammatory cytokines as the exposure, with LBP as the outcome, and the subsequent phase adopted the inverse approach. A total of 41 blood inflammatory cytokines were extracted from the genome-wide association study meta-analysis database, encompassing 8,293 individuals. Data pertaining to LBP were acquired from the Finnish biobank. Primary findings were computed using inverse-variance weighting (IVW), while sensitivity analyses accounting for pleiotropy and invalid instruments were conducted utilizing the weighted-median estimator, MR-Egger, and MR Pleiotropy RESidual Sum and Outlier.ResultsOur results suggest that higher levels of Macrophage migration inhibitory factor (MIF) as well as lower levels of C-C motif chemokine ligand 3 (CCL3) are associated with an increased risk of LBP (odds ratio [OR] = 1.134, 95% confidence interval [CI ]= 1.032–1.245, P = 0.009; OR = 0.887, 95% CI = 0.803–0.980, P = 0.018). Moreover, there was no heterogeneity and horizontal pleiotropy observed in the sensitivity analysis. In contrast, in studies of the effect of LBP on inflammatory cytokines, genetically determined LBP had no causal effect on 41 inflammatory cytokines (IVW P > 0.05).ConclusionsOur study confirms that the levels of circulating MIF and CCL3 may be regarded as valuable circulating inflammatory biomarkers for the management of LBP in clinical practice and as potential molecules for future mechanistic investigation and drug target identification.

Associations between immune cell traits and autoimmune thyroid diseases: a bidirectional two-sample mendelian randomization study.

Autoimmune thyroid diseases (AITDs), mainly including Graves' disease (GD) and Hashimoto's thyroiditis (HT), are common autoimmune disorders characterized by abnormal immune responses targeting the thyroid gland. We conducted a bidirectional two-sample MR analysis using the largest dataset of peripheral immune cell phenotypes from Sardinia, and the AITD dataset from the 10th round of the FinnGen and the UK Biobank project. Instrumental variables (IVs) were rigorously selected based on the three assumptions of MR and analyzed using the Wald ratio, inverse-variance weighted (IVW), MR-Egger, and weighted median methods. Additionally, sensitivity analyses were performed using Cochrane's Q, the Egger intercept, the MR-PRESSO, and the leave-one-out (LOO) method to ensure the robustness of the results. The Steiger test was utilized to identify and exclude potential reverse causation. The results showed that 3, 3, and 11 immune cell phenotypes were significantly associated with the risk of AITD. In GD, the proportion of naive CD4-CD8- (DN) T cells in T cells and the proportion of terminally differentiated CD4+T cells in T cells showed the strongest inducing and protective effects, respectively. In HT, lymphocyte count and CD45 on CD4+T cells showed the strongest inducing and protective effects, respectively. In autoimmune hypothyroidism, CD127 CD8+T cell count and terminally differentiated DN T cell count exhibited the strongest inducing and protective effects, respectively. Through MR analysis, our study provides direct genetic evidence of the impact of immune cell traits on AITD risk and lays the groundwork for potential therapeutic and diagnostic target discovery.

Rheumatoid arthritis and adverse pregnancy outcomes: a bidirectional two-sample mendelian randomization study

BackgroundThere is growing evidence of bidirectional associations between rheumatoid arthritis and adverse pregnancy outcomes (APOs) in observational studies, but little is known about the causal direction of these associations. Therefore, we explored the potential causal relationships between rheumatoid arthritis and APOs using a bidirectional two-sample Mendelian randomization (MR) in European and Asian populations.MethodsWe conducted a bidirectional two-sample Mendelian randomization analysis using available summary statistics from released genome-wide association studies. Summary statistics for instrument–outcome associations were retrieved from two separate databases for rheumatoid arthritis and adverse pregnancy outcomes, respectively. The inverse-variance weighted method was used as the primary MR analysis, and cML-MA-BIC was used as the supplementary analysis. MR-Egger, MR pleiotropy residual sum and outlier (MR-PRESSO), and Cochran Q statistic method were implemented as sensitivity analyses approach to ensure the robustness of the results.ResultsOur study showed that a higher risk of rheumatoid arthritis in the European population was associated with gestational hypertension (OR: 1.04, 95%CI: 1.02–1.06), pre-eclampsia (OR: 1.06, 95%CI: 1.01–1.11), fetal growth restriction (OR: 1.08, 95%CI: 1.04–1.12), preterm delivery (OR:1.04, 95%CI: 1.01–1.07). Furthermore, we found no evidence that APOs had causal effects on rheumatoid arthritis in the reverse MR analysis. No association between rheumatoid arthritis and APOs was found in East Asian population. There was no heterogeneity or horizontal pleiotropy.ConclusionsThis MR analysis provides the positive causal association from rheumatoid arthritis to gestational hypertension, pre-eclampsia, fetal growth restriction and preterm delivery genetically. It highlights the importance of more intensive prenatal care and early intervention among pregnant women with rheumatoid arthritis to prevent potential adverse obstetric outcomes.

No causal relationship between serum vitamin D levels and alcoholic liver disease: a two-sample bidirectional Mendelian randomization study

BackgroundNumerous observational studies have presented an association between Vitamin D (VD) and Alcoholic Liver Disease (ALD). However, sufficient evidence from Randomized Controlled Trials (RCTs) substantiating this correlation is scarce, thus leaving the causality of this relationship ambiguous. To overcome the shortcomings of traditional observational studies, we performed a two-sample bidirectional Mendelian randomization (MR) analysis to ascertain the causal relationship between VD and ALD.MethodsWe utilized summary statistics datasets from Genome-Wide Association Studies (GWAS) for VD and ALD. We selected genetic instruments that measure circulating VD levels (n = 64,979), and retrieved ALD statistics from GWASs, inclusive of 1,416 cases and 217,376 healthy controls, while excluding chronic liver diseases such as nonalcoholic fatty liver disease, toxic liver disease, and viral hepatitis. Subsequent, MR analyses were performed to obtain effect estimates using inverse variance weighted (IVW) random effect models. Cochran’s Q statistic and MR-Egger regression intercept analyses were used to assess pleiotropy. Sensitivity analyses using the MR Egger, weighted median, simple mode, and weighted mode methods were also performed. Leave-one-out analysis was used to identify SNPs with potential effect. Reverse MR analysis was also performed.ResultsIn IVW, our MR analysis incorporated 21 independent SNPs, circulating VD levels had no causal effect on ALD [OR = 0.624 (0.336–1.160), p = 0.136] and ALD had no causal effect on circulating VD [OR = 0.997 (0.986–1.008), p = 0.555]. No heterogeneity or pleiotropy was observed (p &amp;gt; 0.05). Other MR methods also agreed with IVW results.ConclusionThis study provides the causal relationship between genetically predicted circulating Vitamin D levels and ALD and provides new insights into the genetics of ALD.

Causality of inflammatory bowel disease and seborrheic keratosis: A bidirectional two-sample Mendelian randomization study.

Previous studies have revealed a potential link between inflammatory bowel disease (IBD) and seborrheic keratosis (SK). However, whether this association is causal or confounded remains unknown. We conducted this two-sample Mendelian randomization (TSMR) analysis to clarify bidirectional causality between IBD, including its two primary conditions Crohn's disease (CD) and ulcerative colitis (UC), and SK. The summary genetic data of IBD, CD, UC and SK were obtained from accessible genome-wide association studies (GWAS). This TSMR study was primarily performed using inverse-variance weighted (IVW) method, complemented by MR-Egger, weighted median (WM), Bayesian weighted MR (BWMR), MR-robust adjusted profile score (MR-RAPS), MR-pleiotropy residual sum and outlier (MR-PRESSO), and radial IVW MR analyses with modified second-order weights (IVW [Mod 2nd]) methods. Assessment of sensitivity and identification of potential outliers were subsequently conducted to aid interpretation of results. The forward MR results showed that IBD [odds ratio (OR)=1.068, 95% confidence interval (CI)=1.010-1.129, p=0.020) and its subtype CD (OR=1.088, 95%CI=1.038-1.139, p<0.001) increased the risk of SK. However, the occurrence of SK could not be affected by UC (OR=1.090, 95%CI=0.977-1.216, p=0.123). In the reverse analysis, no causal relationship between SK and IBD (OR=0.905, 95%CI=0.813-1.008, p=0.069), UC (OR=0.959, 95%CI=0.860-1.068, p=0.443), and CD (OR=0.933, 95%CI=0.846-1.029, p=0.165) was identified. These findings demonstrate that IBD and its subtype CD could increase the incidence of SK in European populations, whereas SK does not affect IBD occurrence.

No genetic association between sleep traits and periodontitis: A bidirectional two-sample Mendelian randomization study

ABSTRACT Objective This study aimed to investigate the potential genetic link between sleep traits and periodontitis. Methods A two-sample bidirectional Mendelian randomization (MR) analysis was conducted using publicly available genome-wide association studies data on chronotype, daytime sleepiness, daytime napping frequency, insomnia, sleep duration, snoring, and the apnea-hypopnea index (AHI), along with a separate dataset on periodontitis. Results Chronotype (OR = 0.929, 95% CI = 0.788–1.095), daytime sleepiness (OR = 0.492, 95% CI = 0.186–1.306), daytime napping frequency (OR = 1.178, 95% CI = 0.745–1.863), sleep duration (OR = 0.868, 95% CI = 0.644–1.169), AHI (OR = 1.124, 95% CI = 0.980–1.289), insomnia (OR = 0.832, 95% CI = 0.440–1.573), and snoring (OR = 0.641, 95% CI = 0.198–2.075) had no effect on periodontitis. Similarly, periodontitis demonstrated no significant effect on sleep traits. Conclusions There is no evidence of a bidirectional genetic relationship between sleep traits and the risk of periodontitis.

Investigating the association between gut microbiome and aortic aneurysm diseases: a bidirectional two-sample Mendelian randomization analysis

ObjectiveThis study aims to investigate the associations between specific bacterial taxa of the gut microbiome and the development of aortic aneurysm diseases, utilizing Mendelian Randomization (MR) to explore these associations and overcome the confounding factors commonly present in observational studies.MethodsEmploying the largest available gut microbiome and aortic aneurysm Genome-Wide Association Study databases, including MiBioGen, Dutch Microbiome Project, FinnGen, UK Biobank, and Michigan Genomics Initiative, this study performs two-sample bidirectional MR analyses. Instrumental variables, linked to microbiome taxa at significant levels, were selected for identifying relationships with abdominal aortic aneurysms (AAA), thoracic aortic aneurysms (TAA), and aortic dissection (AD). Methods like inverse variance weighted, MR-PRESSO, MR-Egger, weighted median, simple mode, and mode-based estimate were used for MR analysis. Heterogeneity was assessed with the Cochran Q test. MR-Egger regression and MR-PRESSO addressed potential unbalanced horizontal pleiotropy.ResultsThe analysis did not find any evidence of statistically significant associations between the gut microbiome and aortic aneurysm diseases after adjusting for the false discovery rate (FDR). Specifically, while initial results suggested correlations between 19 taxa and AAA, 25 taxa and TAA, and 13 taxa with AD, these suggested associations did not hold statistical significance post-FDR correction. Therefore, the role of individual gut microbial taxa as independent factors in the development and progression of aortic aneurysm diseases remains inconclusive. This finding underscores the necessity for larger sample sizes and more comprehensive studies to further investigate these potential links.ConclusionThe study emphasizes the complex relationship between the gut microbiome and aortic aneurysm diseases. Although no statistically significant associations were found after FDR correction, the findings provide valuable insights and highlight the importance of considering gut microbiota in aortic aneurysm diseases research. Understanding these interactions may eventually contribute to identifying new therapeutic and preventive strategies for aortic aneurysm diseases.

Major depressive disorder elevates the risk of dentofacial deformity: a bidirectional two-sample Mendelian randomization study

BackgroundThe association between psychiatric disorders and dentofacial deformities has attracted widespread attention. However, their relationship is currently unclear and controversial.MethodsA two-sample bidirectional MR analysis was performed to study the causal relationship between dentofacial deformity and eight psychiatric disorders, including major depressive disorder, panic disorder, schizophrenia, bipolar disorder, attention deficit hyperactivity disorder, Alzheimer’s disease, autism spectrum disorder, and neuroticism. Inverse variance weighted, weighted median, MR-Egger regression, weighted mode four methods, and further sensitivity analyses were conducted.ResultsThe major depressive disorder affected dentofacial deformity, with an OR = 1.387 (95% CI = 1.181-1.629, P = 6.77×10-5). No other psychiatric disorders were found to be associated with dentofacial deformity. In turn, dentofacial deformity were associated with neuroticism, with an OR = 1.050 (95% CI = 1.008-1.093, P = 0.018). And there was no evidence that dentofacial deformity would increase the risk of other psychiatric disorders.ConclusionsMajor depressive disorder might elevate the risk of dentofacial deformities, and dentofacial deformity conditions would increase the risk of the incidence of neuroticism.

Undetected Association Between Fatty Acids and Dementia with Lewy Bodies: A Bidirectional Two-Sample Mendelian Randomization Study.

Although observational studies indicated connections between fatty acids (FAs) and Alzheimer's disease and dementia, uncertainty persists regarding how these relationships extend to dementia with Lewy bodies (DLB). To explore the potential causal relationships between FAs and the development of DLB, thus clarifying these associations using genetic instruments to infer causality. We applied a two-sample Mendelian randomization (MR) and multivariable Mendelian randomization (MVMR) approach. Genetic data were obtained from a DLB cohort, comprising 2,591 cases and 4,027 controls of European descent. Eight FAs, including linoleic acid, docosahexaenoic acid, monounsaturated fatty acid, omega-3 fatty acid, omega-6 fatty acid, polyunsaturated fatty acid, saturated fatty acid, and total fatty acid, were procured from a comprehensive GWAS of metabolic biomarkers of UK Biobank, conducted by Nightingale Health in 2020 (met-d), involving 114,999 individuals. Our analysis included inverse-variance weighted, MR-Egger, weighted-median, simple mode, and weighted-mode MR estimates. Cochran's Q-statistics, MR-PRESSO, and MR-Egger intercept test were used to quantify the heterogeneity and horizontal pleiotropy of instrumental variables. Only linoleic acid showed a significant genetic association with the risk of developing DLB in the univariate MR. The odds ratio for linoleic acid was 1.337 with a 95% confidence interval of 1.019-1.756 (pIVW = 0.036). Results from the MVMR showed that no FAs were associated with the incidence of DLB. The results did not support the hypothesis that FAs could reduce the risk of developing DLB. However, elucidating the relationship between FAs and DLB risk holds potential implications for informing dietary recommendations and therapeutic approaches in DLB.

Association between levels of sex hormones and risk of multiple sclerosis: a mendelian randomization study.

This research aimed to examine the causal connections between multiple sclerosis (MS) and a range of sex hormone-related traits, such as bioavailable testosterone (BT), sex hormone-binding globulin (SHBG), testosterone, and estradiol (E2). A bidirectional two-sample Mendelian randomization (MR) analysis using summary statistics from genome-wide association studies (GWAS) was conducted to investigate the relationship between sex hormone-related traits and MS. Moreover, the Inverse-variance weighted (IVW) method was employed as the primary analysis approach. The MR analysis, using the IVW method, found a significant correlation between genetically determined SHBG levels and MS (OR = 1.634, 95% CI: 1.029-2.599, p = 0.038). Similarly, the reverse MR analysis suggested a causal link between MS and SHBG (OR = 1.005, 95% CI: 1.001-1.009, P = 0.003). However, no association was observed between MS risk and E2, testosterone, or BT levels. Our MR analysis demonstrated that genetically predicted higher SHBG may be positively correlated with the risk of MS. Moreover, the role of SHBG in MS could be further investigated.