defined seven major tissue groups (amygdala, basal ganglia, cerebellum, cortex, hippocampus, hypothalamus and spinal cord): principal component analysis (PCA) on the RNA-seq data showed clear clustering by these major tissue groups, resembling brain physiology (Fig. 2b and Supplementary Fig. 6). The genotype data revealed individuals from different ancestries (Fig. 2c and Supplementary Fig. 2), including 5,138, 805 and 208 samples from EUR, AFR and East Asian (EAS) ancestries, respectively. After QC and deduplication, we created six cis-eQTL discovery datasets: Basal ganglia-EUR (n = 208), Cerebellum-EUR (n = 492), Cortex-EUR (n = 2,683), Cortex-AFR (n = 319), Hippocampus-EUR (n = 168) and Spinal cord-EUR (n = 108; Supplementary Table 1 and Fig. 2d). We used Cortex-EAS (n = 208) as a replication dataset. Cis-eQTLs were not calculated for the amygdala and hypothalamus tissue groups due to the small sample size (n < 100).
