When correcting for an increasing number of principal components (PCs), we observed a decrease in the number of trans-eQTLs (Fig. 6a, Supplementary Note, Supplementary Fig. 7 and Supplementary Table 17) as well as in heterogeneity (Supplementary Fig. 26). The majority (85%) of the trans-eQTLs observed without PC correction were located in a 7p21.3 locus previously associated with frontotemporal lobar degeneration40, Alzheimer’s disease (AD)41 as well as changes in neuron proportions42 and gene expression levels43,44. We did not find evidence that these trans-eQTLs were dependent on AD status or neuron proportions and they were not significant when correcting for 100 PCs (Supplementary Note, Supplementary Figs. 26–29 and Supplementary Tables 17–24).
