The GWAS meta-analysis identified 32 independent lead variants (i.e., with a squared correlation (r2) < 0.1 between variants) located in 27 genome-wide significant loci (Fig. 1, Table 1, locus plots in Supplementary Data 1, and forest plots in Supplementary Data 2), including 21 novel loci. No statistically significant heterogeneity was observed between cohorts (Supplementary Fig. 1). The three most strongly associated loci (P < 5 × 10−14) were located on chromosome 1 (in and around PTPRF), chromosome 5 (downstream of MEF2C) and chromosome 11 (downstream of METTL15); the latter is a novel ADHD risk locus. Four loci on chromosomes 1, 5, 11, and 20 had secondary genome-wide significant lead variants (r2 < 0.1 between the index variant and the secondary lead variant within a region of 0.5 Mb), but none remained genome-wide significant in analyses conditioning on the index variant using COJO21 (Supplementary Table 2).
