Assume that a GWAS identifies a highly reproducible and consistently replicated association with a genomic region: what next? The implications are discussed in the next section (ELSI) and additional follow-up experiments are described here (Ioannidis et al., 2009). The fundamental idea is to design experiments to develop a detailed understanding of how changes at the genetic level act and interact with the environment to alter risk of a psychiatric disorder. These experiments should be at multiple levels – DNA, RNA, protein, biological process, cell, local cell systems, organ, organ system, organism, and community levels are all potentially relevant.
