As an alternative to a set threshold, participants discussed a recently published set of guidelines for a standardized and transparent assessment of the evidence of GxE interactions [Boffetta, et al. 2012]. A true GxE interaction is more likely to have strong evidence, replication, protection from bias, and high prior plausibility [Boffetta, et al. 2012]. However, some participants noted these guidelines do not fully address complex issues such as when the multiplicative joint effects are are null for a multiplicative null model but truly interactive compared to an additive null. and exposure-related population stratification. Further, because so much about human physiology is unknown, it is difficult to calibrate the level of a priori knowledge, particularly for agnostic genome-wide approaches.
