GNB5 and attention deficit-hyperactivity disorder: Moreover, a GNB5 mutation (i.e., GNB5 S81L) associated with impaired termination of DA2 receptor signaling was reported in a Saudi family presenting speech impairments and a variable ADHD diagnosis, providing initial clinical evidence for the putative role of GNB5 in the neurobiology of ADHD (Shamseldin et al., 2016).