A Caudate nucleus. B Spinal cord. Top plot, gray dots represent the −log10(P values) for SNPs from the GWAS of MDD, and rhombuses represent the −log10(P values) for probes from the SMR test with solid rhombuses indicating that the probes pass HEIDI test and hollow rhombuses indicating that the probes do not pass the HEIDI test. Middle plot, eQTL results for the probe ENSG000001864770.9 tagging BTN3A2. Bottom plot, location of genes tagged by the probe. Highlighted in maroon indicates probes that pass the SMR threshold. GWAS genome-wide association study, MDD major depressive disorder, SMR summary data-based Mendelian randomization, HEIDI heterogeneity in dependent instruments, eQTL expression quantitative trait loci.