Two studies have investigated whether environmental factors moderate the risk for AD associated with GABRA2. Using probands and control families from the COGA study, Dick, Agrawal, et al. (2006) found that proband carriers of the GABRA2 SNP rs279871 T allele who also had a single stable marriage had substantially lower rates of AD (28%) than those with any other combination of genotype and marital status (41% to 56%). There was a similar non-significant GxE trend among COGA controls. It is noteworthy that a similar pattern of GxE was found in a subsequent study, in which the association between variation in GABRA2 based on 10 SNPs (including rs279871) and trajectories of externalizing behavior from adolescence into young adulthood decreased with higher levels of parental monitoring (Dick et al., 2009b).
