In our gene-based test, ABCB1 met the threshold for genome-wide significance (q-value=0.03). This gene was robustly expressed in brain tissue (maximum expression value across nine brain regions=210). The regional association plot for this gene is shown in Figure 2a. The 17 genes from this analysis meeting a P-value threshold of less than 1 × 10−4 are listed in Table 2, along with their expression values. Two clusters of genes on chromosome 9 appear in this list. As shown in Figures 2b and c, four of these genes are genes for type I interferon (IFNA7, IFNA10, IFNA16 and IFNA17) on chromosome 9p, and five others (STRBP, MIR600, RABGAP1, MIR600HG and ZBTB26) appear in a cluster on chromosome 9q.
