COGA utilized a two‐pronged approach to the study of “candidate genes.” First, candidate genes were selected from linkage regions, resulting in studies linking ADH1B to AUD, 26 , 27 , 28 GABRA2 (from an EEG linkage locus for beta power 17 ) to AUD 18 , 19 as well as other substance use and externalizing behaviors, 29 , 30 , 31 CRHR1 (from a linkage region for EEG power 32 in an independent sample) to P3 amplitude and AUD, 33 CHRM2 (based on an EEG linkage locus 34 ) and substance use disorders, 35 , 36 GRM8 (from an EEG linkage locus) to AUD 37 as well as IQ, 38 and bitter taste receptor genes (e.g., hTAS2R16, on chromosome 7 where maximum drinks demonstrated elevated likelihood of odds of linkage) and AUD. 39 , 40 Second, COGA focused on a very small subset of genes with theoretical biological import, such as DRD2/ANKK1, 41 , 42 , 43 HTT, 44 , 45 , 46 OPRK1 and PDYN, 41 , 47 , 48 , 49 ACN9, 50 NFKB1, 51 tachykinin receptor 3,
