Instrumental variables selection
The SNPs included in the study must meet the three main hypotheses of MR: (i) genetic variation is strongly associated with exposure (correlation hypothesis); (ii) genetic variation is independent of known or unknown confounders (independence hypothesis); (iii) genetic variation is only associated with the outcome of exposure (exclusion hypothesis). To meet the above assumptions we developed the following inclusion criteria: The SNPs incorporated into the study were highly correlated with a significance threshold (