No genome-wide significant heterogeneity was observed in the ADHD GWAS meta-analysis (Supplementary Information). Genetic correlation analysis (Online Methods) provided further evidence that effects were consistent across cohort study designs. The estimated genetic correlation between the European ancestry PGC samples and the iPSYCH sample from LD score regression37 was not significantly less than one (rg = 1.17, SE = 0.20). The correlation between European ancestry PGC case/control and trio cohorts estimated with bivariate GREML was similarly close to one (rg = 1.02, SE = 0.32; Supplementary Table 3).
