We investigated the role of ZNF804A plays in SZ and BD by: i) genotyping the rs1344706 and rs12476147 SNPs in a sample of 428 SZ, 385 BD, and 578 controls from an isolated population from Costa Rica (DeLisi et al., 2001; Morera et al., 2003); and ii) analyzing the rs1344706 allelic specific expression (ASE) in the postmortem dorsolateral prefrontal cortex (DLPFC).