Surprisingly, the weakest results were found for tobacco. Furthermore, our study showed a marginal effect of rs514743 with the risk of first use of alcohol (p value 0.011). This SNP was associated with age of initiation of alcohol and tobacco in a different population sample (Schlaepfer et al. 2008). Rs8040868, which had a marginal effect in Schlaepfer’s study on first use of tobacco, marginally predicted risk of onset of cannabis (p value 0.011). Both marginal effects were in the predicted direction based on previous work, where the more rare variant was associated with higher risk. The risk of first use of inhalants was significantly predicted by rs680244 and rs11637630 (p values 0.004 and 0.002). Rs8023462 and rs11634357 were marginally significant. Rs11637630 significantly predicted risk of onset for other substances.
