Our results should be considered in the context of several limitations. First, there was imperfect correspondence between the study populations and alcohol problems measures across the ALSPAC and FinnTwin12 samples. This concern is lessened in view of the genetic overlap evident between multiple dimensions of alcohol use (Dick et al., 2011). Second, the sample sizes of ALSPAC and FinnTwin12 are relatively small given the growing recognition of the large sample sizes needed to precisely estimate small effect sizes. We recognize that there are larger GWAS of alcohol-related behaviors (e.g., Schumann et al., 2016). Several factors guided our choice to use ALSPAC as our discovery sample, including the greater similarity between the ALSPAC and FinnTwin12 sample populations and alcohol problems phenotypes (in contrast to the aging-related cohorts included in the Schumann et al. (2016) study, as well as that study’s focus on an alcohol consumption phenotype). Third, the polygenic scores derived here include only common variants in regions well tagged by the variants in the 1000 Genomes panel. Fourth, there are alternative enrichment (Finucane et al., 2015) and alternative polygenic scoring
