(all loadings > 0.12) on the first component, suggesting that it represents a general effect across tissues, whereas only brain tissues had strong loadings on the second component (all loadings > 0.12), indicating the importance of brain-specific gene expression effects for these tobacco and alcohol use phenotypes. Pathway enrichment analyses of the TWAS-associated genes identified 1,029 unique gene pathways across phenotypes that were broadly enriched across tissues (Supplementary Table 7), including many of obvious relevance to neurotransmission and neurodevelopment.
