Thus far genome-wide association studies (GWASs) to identify common DNA variants that increase the risk of ADHD have not been successful22. Nevertheless, genome-wide SNP heritability estimates range from 0.10 – 0.2823,24 supporting the notion that common variants comprise a significant fraction of the risk underlying ADHD25 and that with increasing sample size, and thus increasing statistical power, genome-wide significant loci will emerge.
