OBJECTIVES: To investigate the causal associations between autoimmune diseases and aplastic anemia (AA) using Mendelian randomization analysis. METHODS: Publicly available genome-wide association study (GWAS) data were utilized to obtain single nucleotide polymorphisms (SNPs) associated with autoimmune diseases and AA for analysis. The inverse variance weighted (IVW) method was employed as the primary analytical approach, with MR Egger, Weighted Mode, Weighted Median, and Simple Mode methods serving as complementary analyses. Heterogeneity and pleiotropy analyses were conducted using designated functions, and the robustness of Mendelian randomization results was assessed using leave-one-out analysis. RESULTS: The two-sample Mendelian randomization analysis using the IVW method revealed significant positive causal associations of rheumatoid arthritis (OR=1.094, 95% CI: 1.023-1.170, P=0.009, adjusted P=0.042), systemic lupus erythematosus (OR=1.111, 95% CI: 1.021-1.208, P=0.015, adjusted P=0.036), Hashimoto thyroiditis (OR=1.206, 95% CI: 1.049-1.387, P=0.009, adjusted P=0.029), and Sicca syndrome (OR=1.173, 95% CI: 1.054-1.306, P=0.004, adjusted P=0.035) with AA, which was supported by the results from the Weighted Median method. Sensitivity analyses indicated no evidence of pleiotropy or heterogeneity, and leave-one-out analysis confirmed the robustness of the causal relationships. No direct evidence was found linking Graves' disease, ulcerative colitis, Crohn's disease, autoimmune hepatitis, primary biliary cholangitis, or primary sclerosing cholangitis with AA (P>0.05, adjusted P>0.05), indicating a lack of causal association. Reverse Mendelian randomization results and multiple corrections indicated that AA was not an influencing factor for autoimmune diseases (adjusted P>0.05). CONCLUSIONS Our findings support at the genetic level that rheumatoid arthritis, systemic lupus erythematosus, Hashimoto thyroiditis, and Sicca syndrome are risk factors for AA, and confirm a causal association of the these 4 autoimmune diseases with an increased risk of AA.
Humans ; Mendelian Randomization Analysis ; Anemia, Aplastic/genetics* ; Autoimmune Diseases/complications* ; Polymorphism, Single Nucleotide ; Genome-Wide Association Study ; Arthritis, Rheumatoid/genetics* ; Lupus Erythematosus, Systemic/genetics* ; Genetic Predisposition to Disease

Early-onset colorectal cancer (EOCRC) shows a different epidemiological trend compared to later-onset colorectal cancer, with its incidence rising in most regions and countries worldwide. However, the reasons behind this trend remain unclear. The etiology of EOCRC is complex and could involve both genetic and environmental factors. Apart from Lynch syndrome and Familial Adenomatous Polyposis, sporadic EOCRC exhibits a broad spectrum of pathogenic germline mutations, genetic polymorphisms, methylation changes, and chromosomal instability. Early-life exposures and environmental risk factors, including lifestyle and dietary risk factors, have been found to be associated with EOCRC risk. Meanwhile, specific chronic diseases, such as inflammatory bowel disease, diabetes, and metabolic syndrome, have been associated with EOCRC. Interactions between genetic and environmental risk factors in EOCRC have also been explored. Here we present findings from a narrative review of epidemiological studies on the assessment of early-life exposures, of EOCRC-specific environmental factors, and their interactions with susceptible loci. We also present results from EOCRC-specific genome-wide association studies that could be used to perform Mendelian randomization analyses to ascertain potential causal links between environmental factors and EOCRC.
Humans ; Colorectal Neoplasms/etiology* ; Risk Factors ; Genome-Wide Association Study ; Genetic Predisposition to Disease/genetics*

Pelvic organ prolapse (POP), whose etiology is influenced by genetic and clinical risk factors, considerably impacts women's quality of life. However, the genetic underpinnings in non-European populations and comprehensive risk models integrating genetic and clinical factors remain underexplored. This study constructed the first polygenic risk score (PRS) for POP in the Chinese population by utilizing 20 disease-associated variants from the largest existing genome-wide association study. We analyzed a discovery cohort of 576 cases and 623 controls and a validation cohort of 264 cases and 200 controls. Results showed that the case group exhibited a significantly higher PRS than the control group. Moreover, the odds ratio of the top 10% risk group was 2.6 times higher than that of the bottom 10%. A high PRS was significantly correlated with POP occurrence in women older than 50 years old and in those with one or no childbirths. As far as we know, the integrated prediction model, which combined PRS and clinical risk factors, demonstrated better predictive accuracy than other existing PRS models. This combined risk assessment model serves as a robust tool for POP risk prediction and stratification, thereby offering insights into individualized preventive measures and treatment strategies in future clinical practice.
Humans ; Female ; Pelvic Organ Prolapse/epidemiology* ; Middle Aged ; Risk Assessment/methods* ; China/epidemiology* ; Multifactorial Inheritance ; Aged ; Risk Factors ; Genome-Wide Association Study ; Genetic Predisposition to Disease ; Case-Control Studies ; Adult ; Polymorphism, Single Nucleotide ; Genetic Risk Score ; East Asian People

OBJECTIVE: To investigate the potential mechanisms of sepsis pathogenesis in intensive care unit (ICU), with a specific focus on the role of skin microbiota, and to evaluate the causal relationships between skin microbiota and ICU sepsis using Mendelian randomization (MR). METHODS: A two-sample MR analysis was performed using skin microbiota genome-wide association study (GWAS) summary data from German population cohorts as exposures, combined with ICU sepsis susceptibility and 28-day mortality GWAS summary data from the IEU OpenGWAS database as outcomes. The primary causal effect estimates were generated using the inverse variance weighted (IVW) method, supplemented by validation through MR-Egger and weighted median approaches. Heterogeneity and pleiotropy tests, along with sensitivity analyses, were conducted to evaluate the robustness of the results. RESULTS: Regarding risk of ICU sepsis, IVW analysis showed that order Pseudomonadales [odds ratio (OR) = 0.93, 95% confidence interval (95%CI) was 0.88-0.98], family Flavobacteriaceae (OR = 0.93, 95%CI was 0.90-0.96), and genus Acinetobacter (OR = 0.96, 95%CI was 0.93-0.99) were significantly negatively correlated with the risk of ICU sepsis (all P < 0.05). There was a significant positive correlation between the risk of ICU sepsis and the presence of β-Proteobacteria (OR = 1.05, 95%CI was 1.00-1.11) and Actinobacteria (OR = 1.05, 95%CI was 1.00-1.11), both P < 0.05. Regarding 28-day mortality of ICU sepsis, IVW analysis showed that phylum Bacteroidetes (OR = 0.92, 95%CI was 0.86-0.99), family Streptococcaceae (OR = 0.92, 95%CI was 0.85-0.98), family Flavobacteriaceae (OR = 0.90, 95%CI was 0.83-0.97), genus Streptococcus (OR = 0.92, 95%CI was 0.86-0.99), ASV016 [Enhydrobacter] (OR = 0.92, 95%CI was 0.87-0.98), and ASV042 [Acinetobacter] (OR = 0.92, 95%CI was 0.88-0.97) were significantly negatively correlated with the 28-day mortality of ICU sepsis (all P < 0.05); family Moraxellaceae (OR = 1.09, 95%CI was 1.00-1.18) and ASV008 [Staphylococcus] (OR = 1.08, 95%CI was 1.03-1.14) was significantly positively correlated with the 28-day mortality of ICU sepsis (both P < 0.05). Sensitivity analysis and MR-PRESSO showed no heterogeneity, pleiotropy, or horizontal pleiotropy between skin microbiota and ICU sepsis risk and 28-day mortality rate. Analysis of confounding factors showed that single nucleotide polymorphisms (SNPs) associated with relevant skin bacteria could independently and causally affect the risk of ICU sepsis or ICU sepsis related mortality rate, independent of other confounding factors. The Steiger test results indicated that the established causal relationship was not due to reverse causality. CONCLUSIONS Skin microbiota composition may influence both sepsis susceptibility and 28-day mortality in ICU settings. Family Flavobacteriaceae demonstrated protective effects against sepsis onset and mortality. These findings provide new perspectives for early detection and management strategies.
Humans ; Sepsis/mortality* ; Intensive Care Units ; Mendelian Randomization Analysis ; Microbiota ; Skin/microbiology* ; Genome-Wide Association Study ; Risk Factors ; Skin Microbiome

OBJECTIVE: Observational studies have found associations between inflammatory bowel disease (IBD) and the risk of dementia, including Alzheimer's dementia (AD) and vascular dementia (VD); however, these findings are inconsistent. It remains unclear whether these associations are causal. METHODS: We conducted a meta-analysis by systematically searching for observational studies on the association between IBD and dementia. Mendelian randomization (MR) analysis based on summary genome-wide association studies (GWASs) was performed. Genetic correlation and Bayesian co-localization analyses were used to provide robust genetic evidence. RESULTS: Ten observational studies involving 80,565,688 participants were included in this meta-analysis. IBD was significantly associated with dementia (risk ratio [ RR] =1.36, 95% CI = 1.04-1.78; I ² = 84.8%) and VD ( RR = 2.60, 95% CI = 1.18-5.70; only one study), but not with AD ( RR = 2.00, 95% CI = 0.96-4.13; I ² = 99.8%). MR analyses did not supported significant causal associations of IBD with dementia (dementia: odds ratio [ OR] = 1.01, 95% CI = 0.98-1.03; AD: OR = 0.98, 95% CI = 0.95-1.01; VD: OR = 1.02, 95% CI = 0.97-1.07). In addition, genetic correlation and co-localization analyses did not reveal any genetic associations between IBD and dementia. CONCLUSION Our study did not provide genetic evidence for a causal association between IBD and dementia risk. The increased risk of dementia observed in observational studies may be attributed to unobserved confounding factors or detection bias.
Humans ; Mendelian Randomization Analysis ; Inflammatory Bowel Diseases/complications* ; Dementia/etiology* ; Observational Studies as Topic ; Genome-Wide Association Study

OBJECTIVE: Several epidemiological observational studies have related particulate matter (PM) exposure to Inflammatory bowel disease (IBD), but many confounding factors make it difficult to draw causal links from observational studies. The objective of this study was to explore the causal association between PM _2.5 exposure, its absorbance, and IBD. METHODS: We assessed the association of PM _2.5 and PM _2.5 absorbance with the two primary forms of IBD (Crohn's disease [CD] and ulcerative colitis [UC]) using Mendelian randomization (MR) to explore the causal relationship. We conducted two-sample MR analyses with aggregated data from the UK Biobank genome-wide association study. Single-nucleotide polymorphisms linked with PM _2.5 concentrations or their absorbance were used as instrumental variables (IVs). We used inverse variance weighting (IVW) as the primary analytical approach and four other standard methods as supplementary analyses for quality control. RESULTS: The results of MR demonstrated that PM _2.5 had an adverse influence on UC risk (odds ratio [ OR] = 1.010; 95% confidence interval [ CI] = 1.001-1.019, P = 0.020). Meanwhile, the results of IVW showed that PM _2.5 absorbance was also causally associated with UC ( OR = 1.012; 95% CI = 1.004-1.019, P = 0.002). We observed no causal relationship between PM _2.5, PM _2.5 absorbance, and CD. The results of sensitivity analysis indicated the absence of heterogeneity or pleiotropy, ensuring the reliability of MR results. CONCLUSION Based on two-sample MR analyses, there are potential positive causal relationships between PM _2.5, PM _2.5 absorbance, and UC.
Humans ; Mendelian Randomization Analysis ; Particulate Matter/analysis* ; Polymorphism, Single Nucleotide ; Inflammatory Bowel Diseases/genetics* ; Air Pollutants/analysis* ; Crohn Disease/genetics* ; Colitis, Ulcerative/genetics* ; Genome-Wide Association Study ; Risk Factors ; Environmental Exposure

OBJECTIVE: Observational studies have shown inconsistent associations of loneliness or social isolation (SI) with ischemic heart disease (IHD), with unknown mediators. METHODS: Using data from genome-wide association studies of predominantly European ancestry, we performed a bidirectional two-sample Mendelian Randomization (MR) study to estimate causal effects of loneliness ( N = 487,647) and SI traits on IHD ( N = 184,305). SI traits included whether individuals lived alone, participated in various types of social activities, and how often they had contact with friends or family ( N = 459,830 to 461,369). A network MR study was conducted to evaluate the mediating roles of 20 candidate mediators, including metabolic, behavioral and psychological factors. RESULTS: Loneliness increased IHD risk ( OR= 2.129; 95% confidence interval [ CI]: 1.380 to 3.285), mediated by body fat percentage, waist-hip ratio, total cholesterol, and low-density lipoprotein cholesterol. For SI traits, only fewer social activities increased IHD risk ( OR= 1.815; 95% CI: 1.189 to 2.772), mediated by hypertension, high-density lipoprotein cholesterol, triglycerides, fasting insulin, and smoking cessation. No reverse causality of IHD with loneliness and SI was found. CONCLUSION These findings suggested more attention should be paid to individuals who feel lonely and have fewer social activities to prevent IHD, with several mediators as prioritized targets for intervention.
Loneliness/psychology* ; Humans ; Mendelian Randomization Analysis ; Social Isolation ; Myocardial Ischemia/etiology* ; Male ; Female ; Middle Aged ; Genome-Wide Association Study ; Risk Factors ; Aged

OBJECTIVE: To explore the causality between reproductive traits and risk of psoriasis by using a large Mendelian randomization (MR) study. METHODS: A two-sample MR study was performed using summarized statistics from the genome-wide association studies (GWAS) conducted in reproductive traits, as well as GWAS data on overall psoriasis, psoriatic arthritis (PsA), and psoriasis vulgaris (PV). Besides univariable MR (UVMR), multivariable MR and two-step MR was used to calculate the independent effects and quantify the proportion mediated by education or body mass index (BMI). RESULTS: Genetically predicted early age at first sexual intercourse (AFS) led to an increased risk of overall psoriasis [odds ratio ( OR) _UVMR: 0.54]; 36.13% of this effect was mediated through BMI and 47.79% through educational attainment. The direct negative casual association between age at first birth (AFB)-PsA was dominant ( OR _UVMR: 0.76), with 49.61% proportion of the mediation due to BMI. The mediating effect was found for BMI on the AFS-PV relationship, which accounted for 26.27% of the proportion. AFS was inversely associated with the risk of overall psoriasis and PV, with considerable mediation by BMI and educational attainment. CONCLUSION Early AFB may cause a higher risk of PsA, while the AFS-PsA association was fully mediated by BMI.
Humans ; Body Mass Index ; Psoriasis/etiology* ; Mendelian Randomization Analysis ; Educational Status ; Female ; Genome-Wide Association Study ; Risk Factors ; Male ; Reproduction ; Adult

OBJECTIVES: This study aimed to investigate the association between temporomandibular disorder (TMD) and insomnia using a two-sample Mendelian randomization (MR) approach. METHODS: Bidirectional MR analyses of two samples, TMD (n=377 277) and insomnia (n=375 359), were performed using genome-wide association study statistics published in the FinnGen database. Instrumental variables were first screened, and then inverse variance weighting (IVW) and MR-Egger were used as the main-effect assessment methods. Weighted median, weighted mode, and simple mode served as supplementary methods. We used IVW and MR-Egger to test for heterogeneity, as well as MR-Egger intercepts to assess the single nucleotide polymorphism (SNP) potential level of multiplicity effects. Sensitivity analyses were conducted based on leave-one-out to identify potentially influential SNPs. All analyses were conducted by using the two-sample MR R package and were considered statistically significant when P<0.05. RESULTS: MR analysis showed the presence of TMD on insomnia (OR=1.089, 95%CI: 1.017-1.166, P=0.014). Meanwhile, no effect of insomnia on TMD (OR=0.996, 95%CI: 0.964-1.029, P=0.816) was found. The sensitivity-analysis showed that no heterogeneity existed (P>0.05), and the presence of horizontal pleiotropy was not detected (P>0.05). Leave-one-out sensitivity analysis showed no single SNP, which may affect the causal relation. All findings indicated that the causal relationship between TMD and insomnia was not significantly affected by any individual SNP and that IV did not bias the results. CONCLUSIONS Results of MR analyses showed that TMD is a risk factor for insomnia, whereas insomnia is not a risk factor for TMD.
Humans ; Sleep Initiation and Maintenance Disorders/genetics* ; Mendelian Randomization Analysis ; Polymorphism, Single Nucleotide ; Temporomandibular Joint Disorders/complications* ; Genome-Wide Association Study

Intelligence encompasses various abilities, including logical reasoning, comprehension, self-awareness, learning, planning, creativity, and problem-solving. Extensive research and practical experience suggest that there are sex differences in intellectual development, with females typically maturing earlier than males. However, the key genes and molecular network mechanisms underlying these sex differences in intellectual development remain unclear. To date, Genome-Wide Association Studies (GWAS) have identified 507 genes that are significantly associated with intelligence. This study first analyzed RNA sequencing data from different stages of brain development (from BrainSpan), revealing that during the late embryonic stage, the average expression levels of intelligence-related genes are higher in males than in females, while the opposite is observed during puberty. This study further constructed interaction networks of intelligence-related genes with sex-differential expression in the brain, including the prenatal male network (HELP-M: intelligence genes with higher expression levels in prenatal males) and the pubertal female network (HELP-F: intelligence genes with higher expression levels in pubertal females). The findings indicate that the key genes in both networks are Ep300 and Ctnnb1. Specifically, Ep300 regulates the transcription of 53 genes in both HELP-M and HELP-F, while Ctnnb1 regulates the transcription of 45 genes. Ctnnb1 plays a more prominent role in HELP-M, while Ep300 is more crucial in HELP-F. Finally, this study conducted sequencing validation on rats at different developmental stages, and the results indicated that in the prefrontal cortex of female rats during adolescence, the expression levels of the intelligence genes in HELP-F, as well as key genes Ep300 and Ctnnb1, were higher than those in male rats. These genes were also involved in neurodevelopment-related biological processes. The findings reveal a sex-differentiated intelligence gene network and its key genes, which exhibit varying expression levels during the neurodevelopmental process.
Female ; Intelligence/physiology* ; Male ; Sex Characteristics ; Animals ; Brain/growth & development* ; E1A-Associated p300 Protein/physiology* ; beta Catenin/physiology* ; Transcriptome ; Rats ; Gene Expression Profiling ; Genome-Wide Association Study