A wealth of extant biological information, including previous GWAS of similar traits, knowledge of polymorphism function, gene regulation, tissue specific expression patterns and biological organization of genes into pathways can be leveraged to improve our etiological understanding of disease and behavior. For example, an investigator may want to prioritize sites that are epigenetically modified during development in examining the potential mediators of the impact of an intervention or to focus on the genes likely to be involved in a disorder that arises during a particular developmental period (Birnbaum, Jaffe, Hyde, Kleinman, & Weinberger, 2014).
