Our cocaine-derived genetic risk score demonstrated specificity for cocaine dependence severity in the present analyses. It did not predict significant variance in alcohol, tobacco, or marijuana dependence severity (0.003%-0.010%) in the testing sample (N=795), which had at least 80% power to detect effects less than half the size (i.e., 0.25%) observed for cocaine dependence at a very liberal alpha level of 0.50. Given the high p-values (p > 0.78) for all substances other than cocaine, it is likely that even in a large replication sample the cocaine genetic risk score would not account for more than 0.25% of the variance in alcohol, tobacco, or marijuana dependence symptoms.
