A number of studies have argued that the immune system plays a causal role in some psychiatric disorders 59,60. Our results did not implicate any brain immune cell types in psychiatric disorders. We interpret these negative findings cautiously as we did not fully sample the immune system. It is also possible that a small number of genes are active in immune cell types and that these cell types play an important role in the etiology of psychiatric disorders. Finally, if immune functions are salient for a small subset of patients, GWAS may not identify these loci without larger and more detailed studies.
