Third, because most PGC analyses are based on categorical, case vs control analyses, “PGC cases lack clinical depth”. This was by intention: over 10 years ago (43), some of us reasoned that fast phenotype characterization that led to affordably large sample sizes was the logical first step (as opposed to large numbers of phenotypes on small numbers of subjects). This was always the first step. The success of this strategy is seen, not only in the genome-wide significant loci that we have discovered, but also in the many phenotypes that have been associated with PGC GRS in both clinical and population samples. The second step, ongoing now, is detailed characterization of genetically informative subsets of cases (e.g., Aim 2). In addition, some PGC working groups (e.g., substance use disorders) are currently analyzing quantitative phenotypes.
