As indicated in Figure 1, craving was more common in those endorsing a greater number of alcohol dependence criteria, an index of severity. We re-ran association analyses for SNPs in Tables 3 and 4 including number of dependence criteria (0–7) as a covariate. Adjustment for symptom count, as expected, attenuated p-values, in some cases. For genes in the dopamine pathway, after correction, the 3 DRD3 SNPs with the lowest p-values (rs167770, rs226082 and rs324029) continued to show p-values less than 0.05. Three SNPs in SNCA also remained associated (rs6834765, rs11944331 and rs3775439) with p-values indicating a greater degree of significance upon adjustment for severity. For the GWAS, only 2 SNPs (rs1595411 and rs10115971) were no longer associated with craving at p ≤ 0.05 after adjusting for severity. For example, after accounting for number of alcohol dependence criteria, rs2454908 retained a p-value of 0.0002.
