Meta-analysis with the 23andMe cohort also found genome-wide significant heterogeneity at the lead Chromosome 1 locus from the ADHD GWAS meta-analysis (rs12410155: I2 = 97.2, P = 2.29 × 10−9; Supplementary Figures 23–24). This heterogeneity is consistent with the moderate sign concordance, effect size replication, and genetic correlation of the 23andMe cohort with the ADHD GWAS. Notably, the lead chromosome 1 locus in the ADHD GWAS overlaps a reported association with educational attainment78, suggesting this heterogeneity is consistent with the much weaker genetic correlation between the 23andMe results and published GWAS of education-related outcomes. No genome-wide significant heterogeneity was observed in the replication meta-analyses with deCODE or EAGLE/QIMR (Supplementary Figures 25–26, Supplementary Data 6).
