by 0, 1 or 2 (depending on the number of risk alleles that individual carried). The final PRS was the sum of the weighted SNPs. Figure 1 shows the proportion of variance explained (in sample size adjusted r2) in the initial status of heavy episodic drinking by PRS at each p-value threshold. Adjusted r2 values ranged between 1.9–2.3% for males and .8–1.1% for females, which is about what was expected based on previous findings (Salvatore et al., 2014a; Vink et al., 2014). SNPs below the p<.05 threshold were used for the subsequent GxE analyses, as they explained the highest proportion of variance in initial status of heavy episodic drinking.
