is maximized, that is, when the minor allele frequencies are high (e.g., 0.50 for biallelic loci) and when equal numbers of subjects are exposed to the extremes of the environmental moderator (25). Additional factors such as ascertainment strategy (29), study design (30), correlation between the genetic and environmental variables (8), and measurement error in the variables (23) also affect statistical power to detect cG×E effects and should be considered in interpreting results from cG×E studies.
