We tested whether genetic associations with REX were enriched with respect to the transcriptomic profiles of human tissues8 and mouse brain cell types9. At the tissue level, we found the transcriptomic profiles related to brain tissues were associated with REX (Figure 5a). The most significant association was observed with respect to the brain cortex, followed by hypothalamus, amygdala, hippocampus and the basal ganglia. At the cell type level, we found the transcriptomic profile of medium spiny neurons (located in the striatum) to be associated with REX using two different methods (Figure 5b), MAGMA and LDSC, while striatal interneurons were implicated only by MAGMA. A more detailed analysis using narrowly-defined cell types found gene expression of medium spiny neurons and one type of cortical interneuron associated with REX LDSC, while MAGMA implicated two types of hypothalamic neurons, dopaminergic neurons from the ventral tegmental area and striatal interneurons (Figure S4). We observed little association evidence with respect to non-neuronal cell types with REX. Pathway analysis are reported in the Supplement - Table S9.
