Fig. 3: Mendelian randomisation assumptions and schematic representation of study design. | Communications Biology

Fig. 3: Mendelian randomisation assumptions and schematic representation of study design.

From: Genome-wide cross-disease analyses highlight causality and shared biological pathways of type 2 diabetes with gastrointestinal disorders

Fig. 3

The Figure illustrates Mendelian randomisation and its three underlying assumptions30: (1) Genetic variants (SNPs) used as instrumental variables are robustly associated with the exposure, (2) SNPs for the exposure variables are not associated with confounders, and (3) SNPs for the exposure variables influence the outcomes through no other pathway but the exposure. In the first round of analysis, we utilised T2D as exposure variables and GI disorders as outcomes. In the reverse analysis, we used GI disorders as exposures and T2D as the outcome variables. GI gastrointestinal, SNP single nucleotide polymorphism, T2D type 2 diabetes, MR Mendelian randomisation, EA effect allele, NEA non-effect allele, MVMR multivariable MR, MR-PRESSO Mendelian Randomization Pleiotropy RESidual Sum and Outlier.

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