We examined the eight SGIP1 SNPs associated with theta EEG power (Hodgkinson et al., 2010, Table 1) for association with alcohol dependence in an independent sample. Of these, only rs6656912 was not reported as at least modestly associated with alcohol use disorders by Hodgkinson et al. (2010). We analyzed a large, ethnically diverse group of individuals (N = 3988) who had been over-sampled for alcohol dependence from three primary studies of substance dependence and genotyped on the Illumina 1M platform (Bierut et al., 2010). Using a significance threshold of p < 0.05, this sample provided greater than 99% power to detect individual SNP effect sizes similar to those reported by Hodgkinson et al. (2010, Table 1), and at least 80% power to detect effects accounting for at least 0.20% of our sample variance in alcohol dependence. A local ethics review committee approved all study procedures. Taking into account sex, age (dummy coded as quartiles), ancestry (represented by two principal components from a stratification analysis), and original study source (dummy coded to reflect the three primary studies) as covariates, we conducted
