PIDD1 and TIE1 are putatively causal as the increased allelic fold change, from the 2SMR instrument SNP, results in an increased odds ratio (OR) for ADHD (PIDD1, OR 1.34 [1.19-1.51]; TIE1, OR 1.32 [1.20-1.46]). Here, TIE1 is linked to attention deficit-hyperactivity disorder.