Psychopathology in the postgenomic era.

We are rapidly approaching the postgenomic era in which we will know all of the 3 billion DNA bases in the human genome sequence and all of the variations in the genome sequence that are ultimately responsible for genetic influence on behavior. These ongoing advances and new techniques will make it easier to identify genes associated with psychopathology. Progress in identifying such genes has been slower than some experts expected, probably because many genes are involved for each phenotype, which means the effect of any one gene is small. Nonetheless, replicated linkages and associations are being found, for example, for dementia, reading disability, and hyperactivity. The future of genetic research lies in finding out how genes work (functional genomics). It is important for the future of psychology that pathways between genes and behavior be examined at the top-down psychological level of analysis (behavioral genomics), as well as at the bottom-up molecular biological level of cells or the neuroscience level of the brain. DNA will revolutionize psychological research and treatment during the coming decades.