ADGRL3 and attention deficit-hyperactivity disorder: It is particularly compelling that ADGRL3 marker rs4860437, which is a major predictor variable component in the trees for SUD, is in complete LD with ADHD susceptibility markers rs6551665 and rs1947274 in Caucasians28,30,52, suggesting that the phenotype underpinning SUD is under the pleiotropic effect of ADGRL3 variants.