Fig. 1: Principles of Mendelian randomisation (MR) and the assumptions required to obtain an unbiased causal effect estimate.
From: Searching for causal relationships of glioma: a phenome-wide Mendelian randomisation study
The three assumptions are (1) genetic variants used as instrumental variables are only associated with the modifiable risk factor (X), (2) genetic variants are not associated with any measured or unmeasured confounders and (3) genetic variants only influence the risk of developing glioma (Y) through the modifiable risk factor (X). SNP single-nucleotide polymorphism.
