There were also limitations. We examined single-gene associations, which have small effect sizes. Although the current study had the power to detect small effect sizes, we acknowledge that our sample was relatively small, which increases the chance that significant effects were false-positive findings. Complex phenotypes such as disinhibition and externalizing problems are polygenic. There are many other variants within the GABRA2 gene and across the genome that were not examined in the current study but will likely be important to consider in the future. Although several of our results replicated findings from previous studies, the current study did not have a replication sample. Therefore, this study awaits replication with a larger sample, generalization to different ethnic groups, and should be considered preliminary until replicated in an independent sample.
