We provide a more detailed account of limitations in the Supplementary Note, but highlight limitations particularly relevant to future work here. Summary statistics from well-powered GWASs spanning the wide range of psychiatric disorders investigated here were only consistently available for individuals of European ancestry. A major priority for continued work in this area will be to increase the diversity of populations for which psychiatric GWAS are available. Recently developed methods for the stratified analysis of genetic correlations across ancestral populations will be invaluable for the analysis of such data50. Moreover, our results may have been influenced by the phenotyping and case-ascertainment methods used. Cai et al.51 have specifically reported that psychiatric phenotypes derived using minimal phenotyping (defined as “individuals’ self-reported symptoms, help seeking, diagnoses or medication”) may produce GWAS signals of low specificity. Although our sensitivity analyses suggested minimal differences when excluding GWAS that used self-report cohorts, this issue should continue to be explored in future work. It will also be informative for future research to examine further the effect of heterogeneity in how samples are ascertained and disorders are assessed on genetic relationships among disorders52.
