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Alterations of the gut microbiota, often referred to as gut dysbiosis, have been associated with several chronic diseases and longevity in pre-clinical models as well as in observational studies. Whether these relationships underlie causal associations in humans remains to be established. We aimed to determine whether gut dysbiosis influences the risk of chronic diseases and longevity using a comprehensive 2-Sample Mendelian randomization (2SMR) approach. We included as exposures inflammatory bowel disease (IBD) as a human model of gut dysbiosis, 11 gut-associated metabolites and pathways and 48 microbial taxa. Study outcomes included eight chronic diseases previously linked with gut dysbiosis using observational studies (Alzheimer’s disease, depression, type 2 diabetes, non-alcoholic fatty liver disease, coronary artery disease (CAD), stroke, osteoporosis and chronic kidney disease) as well as parental longevity and life expectancy. Neither IBD, nor gut-associated metabolites were causally associated with chronic disease or lifespan. After multiple testing correction for 582 tests, no microbial taxa-chronic disease associations remained significant. After robustness analyses and multivariate MR to correct for body mass index and alcohol intake on all 42 nominally significant causal relationships, four associations remained. Altogether, results of this multidimensional Mendelian randomization study suggest that gut dysbiosis has little impact on chronic diseases and human longevity and that previous documented associations may not underly causal relationships. Studies with larger sample sizes and more optimal taxonomic discrimination may ultimately be required to determine whether the human gut microbiota plays a causal role in the etiology of chronic diseases and longevity.

Background: There is lack of data on the incidence of Parkinson’s disease (PD) based on repeat studies. Mortality rates of PD in Estonia have never been studied before. Objectives: To estimate the incidence and mortality rates of PD in ­Estonia, to compare current incidence rates with those of the prior epidemiological study in Estonia, and to examine the reported causes of death of the study population. Methods: Eligible subjects were identified from multiple case-finding sources. Subjects were subsequently tracked on the Electronic-Health Record until either the end of the study, or their death. Incidence rates and standardized mortality ratios (SMR) were calculated. Causes of death were identified, based on the data from death certificates. Results: In the current study, the overall age-adjusted incidence rate was 28.0/100,000 person-years (95% CI 25.2–30.8). Compared with the previous study, the age-adjusted incidence rate inEstonia has not significantly changed (rate ratio 1.11; p = 0.19). Overall SMR for the inception cohort of PD cases with a median follow-up time of 5 years was 1.12 (95% CI 0.88–1.36; p = 0.3). For those deceased subjects known to have had clinically diagnosed PD, this was mentioned on 46.8% of death certificates. Conclusions: Over the last 20 years, the overall incidence of PD in Estonia has remained comparatively stable. The data did not show an excess mortality in PD patients (vs. general population) in the first 5 years of the disease.

Non-alcoholic fatty liver disease (NAFLD) is a complex disease linked with several chronic diseases. We aimed at identifying genetic variants associated with NAFLD and evaluate their functional consequences. We performed a genome-wide meta-analysis of four cohorts of electronic health record-documented NAFLD in participants of European ancestry (8434 cases and 770,180 controls). We identified five potential susceptibility loci for NAFLD (located at or near GCKR, TR1B1, MAU2/TM6SF2, APOE, and PNPLA3). We also report a potentially causal effect of lower LPL expression in adipose tissue on NAFLD susceptibility and an effect of the FTO genotype on NAFLD that is likely explained by obesity. Positive genetic correlations between NAFLD and cardiometabolic diseases and risk factors such as body fat accumulation/distribution, lipoprotein-lipid levels, insulin resistance and coronary artery disease and negative genetic correlations with parental lifespan, socio-economic status and acetoacetate levels were observed. Altogether, this large GWAS meta-analysis revealed new insights into the genetic architecture of NAFLD. Funding: Part of this study was supported by the European Union through the European Regional Development fund. The work of Estonian Genome Center, Univ. of Tartu has been supported by the European Regional Development Fund and grants No. GENTRANSMED (2014-2020.4.01.15-0012), MOBERA5 (Norface Network project no 462.16.107) and 2014-2020.4.01.16-0125. This study was also funded by the European Union through Horizon 2020 research and innovation programme under grant no 810645 and through the European Regional Development Fund project no. MOBEC008 and Estonian Research Council Grant PUT1660. Ethical Approval: This study and the use of data from 4119 cases and 190,120 controls was approved by the Research Ethics Committee of the University of Tartu (Approval number 288/M-18).

Non-alcoholic fatty liver disease (NAFLD) has been associated with several blood biomarkers and chronic diseases. Whether these associations underlie causal effects remains to be determined. We aimed at identifying blood metabolites, blood proteins and human diseases that are causally impacted by the presence of NAFLD using Mendelian randomization. We created a NAFLD genetic instrument from NAFLD loci (MTARC1, GCKR, LPL, TRIB1, LMO3, FTO, TM6SF2, APOE and PNPLA3) identified in a new electronic health record based-GWAS meta-analysis (6715 cases and 682,748 controls). We found a potentially causal effect of NAFLD on tyrosine metabolism as well as on blood levels of eight proteins that could potentially represent new early biomarkers of NAFLD. Using results from the UK Biobank, FinnGen and the COVID-19 Host Genetics Initiative, we found that NAFLD was not causally associated with diseases outside the spectrum of liver diseases, suggesting that the resolution of NAFLD might not prevent other diseases.

Summary Non-alcoholic fatty liver disease (NAFLD) is a complex disease linked to several chronic diseases. We aimed at identifying genetic variants associated with NAFLD and evaluating their functional consequences. We performed a genome-wide meta-analysis of 4 cohorts of electronic health record-documented NAFLD in participants of European ancestry (8,434 cases and 770,180 controls). We identify 5 potential susceptibility loci for NAFLD (located at or near GCKR, TR1B1, MAU2/TM6SF2, APOE, and PNPLA3). We also report a potentially causal effect of lower LPL expression in adipose tissue on NAFLD susceptibility and an effect of the FTO genotype on NAFLD. Positive genetic correlations between NAFLD and cardiometabolic diseases and risk factors such as body fat accumulation/distribution, lipoprotein-lipid levels, insulin resistance, and coronary artery disease and negative genetic correlations with parental lifespan, socio-economic status, and acetoacetate levels are observed. This large GWAS meta-analysis reveals insights into the genetic architecture of NAFLD., Graphical abstract, Highlights This analysis identifies 5 genetic loci for non-alcoholic fatty liver disease Non-alcoholic fatty liver disease loci are GCKR, TR1B1, TM6SF2, APOE, and PNPLA3 Adipose tissue LPL expression may influence non-alcoholic fatty liver disease The FTO genotype may affect non-alcoholic fatty liver disease susceptibility, To gain insight into the genetic architecture of non-alcoholic fatty liver disease (NAFLD), Ghodsian et al. performed a genome-wide meta-analysis of electronic health record-documented NAFLD and identify 7 potential susceptibility loci for this disease (located at or near GCKR, TR1B1, LPL, FTO, MAU2/TM6SF2, APOE, and PNPLA3).

Background: Non-alcoholic fatty liver disease (NAFLD) is the most prevalent form of liver disease. Observational studies documented associations of NAFLD with several chronic and infectious diseases but whether these associations underlie causal effects is unknown. The molecular mechanisms and genetic architecture of NAFLD are poorly understood. Our objectives were to identify genetic loci associated with NAFLD and determine whether the presence of NAFLD was causally associated with human diseases. Methods: We created a NAFLD genetic instrument through the identification of independent single-nucleotide polymorphisms (SNPs) associated with NAFLD in a meta-analysis of genome-wide association study (GWAS) (6715 cases and 682,748 controls). Using inverse-variance weighted Mendelian Randomization (MR), we investigated the impact of NAFLD on human disease-related phenotypes in the UK Biobank and FinnGen cohorts as well as in the COVID-19 host genetics initiative. Results: We first performed a GWAS meta-analysis of four cohorts and found variants significantly associated with NAFLD (p800 diseases) using a genetic instrument for NAFLD. Results of these analyses suggest that NAFLD was not causally associated with diseases outside the spectrum of liver diseases. We also found no causal association between genetically predicted NAFLD and COVID-19-related outcomes. Conclusions: This study identified several new genetic loci associated with NAFLD. NAFLD was not causally associated with diseases outside those of the spectrum of liver diseases. This finding suggests that the resolution of NAFLD might not prevent other diseases previously associated with NAFLD.

Objectives Levodopa is the most effective therapy for treating Parkinson's disease (PD); however, side effects such as dyskinesias and motor fluctuations may occur after some years of its usage. The aims of this study were to assess the frequency of and factors associated with motor complications among PD patients on levodopa treatment. Methods In a cross-sectional study carried out in 2010–2013, clinical data and treatment details were collected. Logistic regression expressed by odd ratios (OR) and 95% confidence intervals (CI) was conducted to examine the effects of several independent variables on the occurrence of motor complications. Results A total of 455 patients were enrolled, among whom 374 were on levodopa. Analysis was performed in 328 patients whose exact duration of levodopa treatment was known. Among patients included in the analysis, 25.9% experienced motor complications; of these, 21% had dyskinesias and 20.1% had motor fluctuations. Based on logistic regression, statistically significant factors associated with the occurrence of motor complications were younger age at onset of the disease, higher levodopa equivalent daily dose (LEDD), shorter time to levodopa initiation, and akinetic-rigid dominant phenotype of PD. Conclusions This study suggests that postponing the start of levodopa therapy and maintaining low daily doses of levodopa might reduce the risk of motor complications. Our results confirm that due to higher risk of motor complications, effectively treating patients with akinetic-rigid dominant phenotype of PD might be more challenging than for patients whose dominant symptom is tremor.