GWAS efforts tend to focus largely on psychiatric outcomes, and on adults, since adolescents are not usually through the period of risk. Accordingly, the strategy in studying genetic influences on adolescent behavior has been to take genes identified in adult samples and study how they influence behavior earlier in adolescence. A prime example of this study model is found with GABRA2, the gamma-aminobutyric acid type A receptor alpha2 subunit gene. GABRA2 was initially identified in a GWAS of adult samples as a risk factor for alcohol dependence (Edenberg et al., 2004). Dick and colleagues then investigated the role of GABRA2 in an adolescent sample finding that the gene was significantly associated with conduct disorder in childhood (association with alcohol dependence did not reach significance until late adolescence; Dick et al., 2006a). Further studies have continued to implicate GABRA2 in developmental paths to externalizing phenotypes (Dick et al., 2013a; Dick et al., 2013b; Dick et al., 2009b; Latendresse et al., 2015; Salvatore et al., 2015).
