In this review of the literature, only a handful of significant gene-environment interactions influencing cigarette use were identified and none were replication studies. To ensure that these findings are not false positives, replication studies using alternative samples are needed. It has been suggested elsewhere that gene-environment interaction studies will be underpowered to detect effects under the following conditions: when the estimated main effects of genes are weak, when the genetic effect is found only among individuals exposed to a particular environmental risk, and when environmental influences are not detected because risk is only conferred among individuals with genetic liability (6). Replications of findings from studies that have identified significant gene-environment interactions influencing cigarette use would imply that the under-examined role of genetic factors in response to particular environments would be an important step in efforts to further reduce smoking rates (102).
