An early analysis of five overlapping psychiatric conditions (ADHD, bipolar disorder, ASD, schizophrenia, and MDD) revealed four genome-wide significant loci near the genes ITIH3, AS3MT, CACNB2, and CACNA1C, with the first three showing relevance to ADHD (30, 32). Here, ITIH3 is linked to attention deficit-hyperactivity disorder.