EEG data were available on a subset of the sample who were participants in the Collaborative Study on the Genetics of Alcoholism (COGA) (N = 1066). This sample provided 93% power to detect individual SNP effect sizes similar to the average effect size (i.e., 1.1%) reported by Hodgkinson et al. (2010), and at least 80% power to detect effect sizes of at least 0.72%. Elevated resting EEG theta has been found to be a marker of alcoholic status in the COGA sample (Rangaswamy et al., 2003). Analyses of the eight selected SGIP1 SNPs were performed on the same resting theta phenotype as described by Hodgkinson et al. (2010), with log-transformed mean values of the five posterior electrodes (P3, Pz, P4, O1, and O2) at 3–8 Hz. Age, sex, and ancestry (as previously described) were incorporated as covariates in the linear regression models. There was no evidence for association between the selected SNPs in SGIP1 and theta power (see Table 1), with p-values between 0.40 and 0.90 for the combined group. Results remained non-significant when analyses were split by race (identified
