subtle modification of gene transcription and translation [34]. The connection between genetic variation and gene expression may identify functional loci not previously associated with AD, as well as offer specific, testable hypotheses for polymorphisms associated with AD [34–36]. Recent studies in rodent models have identified hub genes which play a role in the behavioral responses to alcohol by a coordinate analysis of acute alcohol-responsive gene networks, linked genetic intervals, and alcohol behavioral responses [37]. Linkage disequilibrium (LD) of eQTLs with genetic variants implicated in AD and ARPs can provide a biological mechanism for disease-associated variants with no otherwise apparent functions as there is empirical evidence suggesting that eQTLs are over-represented among GWAS signals [38, 39].
