a genome wide association study (GWAS) between all available SNPs across the genome and phenotypes in a discovery sample. Then, beta weights for each SNP are used in a separate target sample to compute an additive “risk score” for all individuals given their specific alleles. These authors did indeed find a significant relation between polygenic risk scores and externalizing in an independent target sample. Nevertheless, this approach is genome-wide, and therefore agnostic about the sources of association, and it does not leverage the hypothesis-driven selection of candidate genes that have emerged from the extant literature. The approach used in the current study, therefore, may provide more stable estimates of genetic risk than candidate gene studies, while still proving some specificity regarding target genes compared to a genome-wide polygenic risk score approach.
