The most notable limitation is the relatively modest sample size in the primary GWAS. Nevertheless, this is the only GWAS of EEG coherence conducted to date. In addition, several highly correlated SNPs with genome-wide significance were associated with low theta EEG coherence and more modestly with alcohol related behaviors and posterior corpus callosum volume in our primary sample. Importantly, they were also associated with alcohol consumption and posterior corpus callosum volume in an independent sample. This region of 18q23 has been previously associated with other neuropsychiatric traits of potential relevance to neural connectivity and alcohol use behavior in both human and animal data. Given the modest sample size for GWAS and lack of direct replication sample available for theta EEG coherences, and nominal associations observed in eQTL analyses, all findings must be replicated in larger samples. Recent GWAS of alcohol use behaviors31,90 have not, however, found variants in this region of chromosome 18 to be genome-wide significant. In addition, it will be important for future work to combine the advantages of the superior spatial resolution of MRI and the superior
