To identify and prioritize ADHD risk genes, we also performed a transcriptome-wide association study (TWAS) of the genetically regulated gene expression using EpiXcan28 and expression data from the PsychENCODE Consortium29 on genes as well as isoforms detected in 924 samples from the dorsolateral prefrontal cortex (DLPFC). The TWAS identified 15 genes (Supplementary Table 11) and 18 isoforms (Supplementary Table 12), which together identified 23 distinct genes (Supplementary Fig. 6) with significantly different predicted gene expression levels in ADHD cases compared to controls (after Bonferroni correction for all the 34,646 genes and isoforms tested; Supplementary Fig. 6). Eight of the genes were among the 76 genes mapped by credible variants in FUMA. When using a less stringent correction (false discovery rate < 5%), we identified 237 genes with different predicted expression among cases and controls, of which 19 were also among the 76 prioritized risk genes. The B4GALT2-205 isoform located in the genome-wide significant locus on chromosome 1 showed the strongest association (P = 7 × 10−11), with lower predicted expression in ADHD compared to controls (Supplementary Fig. 7a). The expression
