Much of the observed variance of brain-specific genes in bulk tissue is explained by cellular composition effects. (A) Groups of genes associated with brain-specific functional terms tend to have higher cellular composition-associated variance (indicated by higher average R2 values) compared to groups of genes associated with housekeeping terms. The average R2 values for two example terms are highlighted with black and blue dots. (B) Distribution of gene-level variance in the GTExBulk and sNuc-seq cell population (Exc L2-3 LINC00507 FREM3) for two groups of genes. Genes associated with brain-specific term “Regulation of synaptic plasticity” have higher variance than genes associated with the housekeeping term “Histone demethylation” in the GTExBulk data set, whereas they have slightly but significantly lower variance in the sNuc-seq cell population.
