SMR was run using eQTL meta-analysis summary statistics from European populations for blood from eQTLGen,77 and five nervous system tissues from MetaBrain (Basalganglia, Cerebellum, Cortex, Hippocampus and Spinal Cord).78 SMR was run using default settings. The HEIDI test is performed alongside SMR to test for effect size heterogeneity between the GWAS and eQTL summary statistics, which would indicate that they are driven by different causal variants. The HEIDI test is a frequentist approach that is analogous to colocalization used to check for shared causal variants underlying TWAS associations.
