For pragmatic reasons, psychiatric GWAS outcomes are typically at the level of comparing those with and without a disorder. This has the advantage of being able to combine across cohorts utilizing various ascertainment strategies in order to obtain the extremely large sample sizes necessary to achieve adequate power. One downside with respect to cross-disorder efforts is that this will aggregate across potential subgroups within a disorder, or clusters of disorder symptoms, that may be more tightly linked with other disorders. The PRS analyses noted above highlight a particular example where certain presentations of BIP may be characterized by higher levels of genetic overlap with SCZ. Methods like BUHMBOX (Han et al., 2016) can be used to detect whether there are particular subgroups within a disorder that drive genetic correlations with other disorders. Initial findings have not found evidence for these subgroups within MDD (Howard et al., 2020), but this remains to be tested across other disorders. Extraordinary efforts are also underway to collect symptom level data for individual disorders. In addition, electronic health records (EHRs) are becoming an increasingly utilized
