Mendelian Randomization Analysis Dissects the Relationship between NAFLD, T2D, and Obesity and Provides Implications to Precision Medicine
Xiaocheng Charlie Dong,
Y Eugene Chen,
Posted 07 Jun 2019
bioRxiv DOI: 10.1101/657734 (published DOI: 10.1016/j.jhep.2020.03.006)
Posted 07 Jun 2019
Background: Non-alcoholic fatty liver disease (NAFLD) is epidemiologically correlated with both type 2 diabetes (T2D) and obesity. However, the causal inter-relationships among the three diseases have not been completely investigated. Aim: We aim to explore the causal relationships among the three diseases. Design and methods: We performed a genome-wide association study (GWAS) on fatty liver disease in ~400,000 UK BioBank samples. Using this data as well as the largest-to-date publicly available summary- level GWAS data, we performed a two-sample bidirectional Mendelian Randomization (MR) analysis. This analysis tested the causal inter-relationship between NAFLD, T2D, and obesity, as well as the association between genetically driven NAFLD (with two well-established SNPs at the PNPLA3 and TM6SF2 loci) and glycemic and lipidemic traits, respectively. Transgenic mice expressing the human PNPLA3 I148I (TghPNPLA3-I148I) and PNPLA3 I148M (TghPNPLA3- I148M) isoforms were used to further validate the causal effects. Results: We found that genetically instrumented hepatic steatosis significantly increased the risk for T2D (OR=1.3, 95% CI: [1.2, 1.4], p=8.3e-14) but not the intermediate glycemic phenotypes at the Bonferroni-adjusted level of significance (p<0.002). There was a moderate, but significant causal association between genetically driven hepatic steatosis and decreased risk for BMI (β=- 0.027 SD, 95%CI: [-0.043, -0.01], p=1.3e-4), but an increased risk for WHRadjBMI (Waist-Hip Ratio adjusted for BMI) (β=0.039 SD, 95%CI: [0.023, 0.054], p=8.2e-7), as well as a decreased level for total cholesterol (β=-0.084 SD, 95%CI [-0.13, -0.036], p=6.8e-4), but not triglycerides (β=0.02 SD, 95%CI [-0.023, 0.062], p=0.36). The reverse MR analyses suggested that genetically driven T2D (OR=1.1, 95% CI: [1.0, 1.2], p=1.7e-3), BMI (OR=2.3, 95% CI: [2.0, 2.7], p=1.4e-25) and WHRadjBMI (OR=1.5, 95% CI: [1.3, 1.8], p=1.1e-6) causally increase the NAFLD risk. In the animal study, as compared to the TghPNPLA3-I148I controls, the TghPNPLA3-I148M mice developed higher fasting glucose level and reduced glucose clearance. Meanwhile, the TghPNPLA3-I148M mice demonstrated a reduced body weight, increased central to peripheral fat ratio, decreased circulating total cholesterol as compared to the TghPNPLA3-I148I controls. Conclusion: This large-scale bidirectional MR study suggests that lifelong, genetically driven NAFLD is a causal risk factor for T2D (hence potentially a "NAFLD-driven T2D" subtype) and central obesity (or "NAFLD-driven obesity" subtype), but protects against overall obesity; while genetically driven T2D, obesity, and central obesity also causally increase the risk of NAFLD, hence a "metabolic NAFLD". This causal relationship revealed new insights into disease subtypes and provided novel hypotheses for precision treatment or prevention for the three diseases.
- Downloaded 895 times
- Download rankings, all-time:
- Site-wide: 45,502
- In epidemiology: 2,294
- Year to date:
- Site-wide: 135,915
- Since beginning of last month:
- Site-wide: 58,633
Downloads over time
Distribution of downloads per paper, site-wide
- 27 Nov 2020: The website and API now include results pulled from medRxiv as well as bioRxiv.
- 18 Dec 2019: We're pleased to announce PanLingua, a new tool that enables you to search for machine-translated bioRxiv preprints using more than 100 different languages.
- 21 May 2019: PLOS Biology has published a community page about Rxivist.org and its design.
- 10 May 2019: The paper analyzing the Rxivist dataset has been published at eLife.
- 1 Mar 2019: We now have summary statistics about bioRxiv downloads and submissions.
- 8 Feb 2019: Data from Altmetric is now available on the Rxivist details page for every preprint. Look for the "donut" under the download metrics.
- 30 Jan 2019: preLights has featured the Rxivist preprint and written about our findings.
- 22 Jan 2019: Nature just published an article about Rxivist and our data.
- 13 Jan 2019: The Rxivist preprint is live!