In conclusion, these data represent the first genome-wide scan using ASPD as a phenotype. The results corroborated the possible importance of several chromosomal regions highlighted in prior linkage studies for conduct disorder and other externalizing phenotypes and identify new regions of the genome. The results of this study should be interpreted in the context of several limitations. First, the sample size was limited and replication of the findings in a larger sample within this population is necessary. Second, the findings may not generalize to other Native Americans. Third, comparisons of linkage findings to non-Indian populations may be limited by differences in a host of potential genetic and environmental variables. Fourth, the underlying assumption that these phenotypes are normally distributed, an assumption of variance component analyses, may not be warranted. Finally, because this population has significant admixture, estimates of allele frequencies may produce biased LOD scores. Despite these limitations, this report represents an important first step in an ongoing investigation to understand the genetic determinants associated with the development of substance use disorders in this high risk and understudied ethnic group.
