By virtue of the numbers of investigators, subjects, and data points, the PGC is the largest consortium and biological experiment in the history of psychiatry. The PGC currently has over 160 investigators from 65 institutions in 19 countries. Membership has been extended to groups with high-quality GWAS data and usually include the study principal investigator and key collaborators. Joining the PGC entails reading and agreeing to the rules of behavior detailed in a memorandum of understanding. Assent is indicated by email and effectively constitutes a pledge to behave with integrity. The PGC sponsored a series of papers outlining the history of genetic inquiries in psychiatry, a framework for interpretation of GWAS, and issues pertaining to comorbidity between disorders (Table 1).
