The Psychiatric Genomics Consortium (PGC) has led the way in coordinating these efforts for psychiatric disorders. The exemplar for the new, more successful gene identification strategy has been schizophrenia, a rare psychiatric disorder whose high heritability of ~80% (Sullivan et al., 2003) made it a top candidate for gene identification. Results from the first report of the schizophrenia PGC group initially remained disappointing – despite having over 9,000 cases, only 5 genome-wide significant associations were found [The Schizophrenia Psychiatric Genome-Wide Association Study (GWAS) Consortium, 2011]. However, it was subsequently discovered that the return on investment was not linear. Doubling and even tripling the sample size yielded only a handful of additional results; however, 108 significant loci were found when a pooled sample of 37,000 cases and 113,000 controls was analyzed, with polygenic risk scores, calculated by weighting findings across the genome, 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
