However, the concordance between studies in identifying general areas in the genome that are associated with externalizing phenotypes suggests that the search for candidate genes within those locations may be productive in identifying some general mechanisms that may underlie these behaviors. In one recent study, for instance, Dick et al., (2006) found that the GABRA2 gene was associated with childhood conduct disorder symptoms in children and adolescents. GABRA2 is located on chromosome 4 in the general region that an area of interest for the ASPD/CD phenotype in these American Indians was found, and which Long et al., (1998) found linked to alcohol dependence in Southwest Indians. One region that may be intriguing is the area on chromosome 3 reported by Stallings et al., (2003,2005) for conduct symptoms and drug abuse vulnerability. This general location was also uncovered in the present study and it harbors genes for the 5-hydroxytyrptamine receptor 3 (HTR3D, HTR3E). Preclinical studies have demonstrated the important role of serotonin pathways in drug abuse liability and as such 5-HT receptors may be an important target of study (see Barr
