Some prevention studies are now incorporating polygenic risk scores (PRS)(Musci et al., 2016), in which a weighted score is created based on a linear combination of risk variants identified in another, larger gene identification study (Li et al., 2017; Musci et al., 2016; Salvatore et al., 2015). These scores are also referred to as genome-wide polygenic scores (GPS)(Webb et al., 2017), to eliminate reference to “risk”, for the reasons delineated above. For a handful of psychiatric and behavioral traits for which extremely large gene identification consortia have already amassed hundreds of thousands of individuals, these polygenic scores are beginning to account for non-trivial portions of the variance. For example, for schizophrenia, 108 significant loci were found when a pooled sample of 37,000 cases and 113,000 controls was analyzed, with polygenic risk scores accounting for 7% of the variance in disorder liability(Schizophrenia Working Group of the Psychiatric Genomics Consortium, 2014). A similar story has been found for other complex, highly heritable traits such as height, where no significant variant associations were detected with 5,000 genomes, but an analysis of 250,000 individuals
