RAC1 and Intellectual disability: Mutations in several genes encoding guanine exchange factors and GTPase-activating proteins that regulate the on/off state of RAC1 have been identified to cause rare neuronal disorders.33,34 Indeed, analysis of a protein–protein interaction subnetwork extracted from the human-integrated protein–protein interaction reference database35 reveals RAC1 to have 25 first-order interactors reported to be causative of intellectual disabilities.