Given that four GABRA2 SNPs were associated with both Impulsiveness and LAPS, we tested whether impulsiveness may mediate the effect of GABRA2 on LAPS. We selected the four SNPs that showed association with both Impulsiveness and LAPS (rs10805145, rs426463, rs279827 and rs279826) to test for mediation. Table 3 reports the standardized results of the model-based bootstrap that directly tests the significance of mediation effects using 2,000 samples from the original data. Evidence for partial mediation was observed for all four SNPs. Specifically, the indirect effect of GABRA2 on LAPS was significant for all four SNPs and the direct effect of GABRA2 on LAPS remained significant. On average, 22.6% of the relation of GABRA2 SNPs was due to impulsiveness, with SNP rs279827 showing the highest mediated effect, of 23.2%.
