SMR22 was performed using default settings and eQTL meta-analysis summary statistics from European populations for whole blood from eQTLGen23, and all five nervous system tissues from MetaBrain (basal ganglia, cerebellum, cortex, hippocampus and spinal cord)105. The HEIDI (heterogeneity in dependent instruments) test is performed alongside SMR to test for effect size heterogeneity between the GWAS and eQTL summary statistics. Both SMR and TWAS have a number of important assumptions and limitations, which we discuss in Supplementary Note 9.
