However, such findings are unusual for many common psychiatric disorders (Figure 2), and connecting the numerous common variant association signals to genes can be challenging. Figure 4 illustrates typical patterns of results. Figure 4a shows the CACNA1C intronic association for schizophrenia; a subsequent study suggested that these variants interact with a regulatory element for CACNA1C (52). Figure 4b depicts the region surrounding DRD2 (encoding a key target of antipsychotics). This association has been functionally connected to DRD2 via DNA-DNA regulatory loops (53). Figure 4c shows a multigenic region—the association region covers many brain-expressed genes associated with multiple human traits. Figure 4d depicts a region associated with schizophrenia but far from any known protein-coding gene.
