Human behavioral genomics

Abstract

Summary Weare rapidly approaching a postgenomic era in which we will know the entire genome sequence and, most importantly to human behavioral genetics, all the variations in the genome sequence. These DNA polymorphisms are the source of hereditary influence and will revolutionize human behavioral genetics, especially links between genes, brain and behavior.Attention is now focused on finding genes for complex quantitative traits influenced by multiple genes (called quantitative trait loci, QTLs) as well as environmental factors. Behavioral disorders and dimensions are the most complex of all quantitative traits. Progress in identifying genes for complex traits has been slower than expected in part because research has lacked statistical power to detect genes of small effect size. Research designs are needed that can break the 1% QTL barrier.Much has been learned and remains to be learned using quantitative genetic techniques that can disentangle genetic and environmental influences. In addition to demonstrating that genetic influence is substantial for most behavioral disorders and dimensions, quantitative genetic techniques can be used to assess genetic and environmental influences on covariance between behavioral traits or between behavioral and biological traits (multivariate genetics), to chart genetic change as well as continuity during development (developmental genetics), and to investigate interactions and correlations between genes and environment (environmental genetics). This research can chart the course for molecular genetic attempts to identify QTLs.The greatest impact of the postgenomic era on human behavioral genetics research will come after specific genes have been identified that contribute to the ubiquitous heritability of behavioral traits. The future of genetic research lies in moving from finding genes (genomics) to finding out how genes work (functional genomics). Functional genomics is usually considered in terms of bottomup molecular biology at the cellular level of analysis. However, a top-down behavioral level of analysis (behavioral genomics) might pay off more quickly in predicting, diagnosing, treating and preventing problems. Bottom-up and top-down levels of analysis of gene-behavior pathways will eventually meet in the brain.