The IQSEC1 and IQSEC2 proteins are Ca+/CaM-regulated synaptic proteins that can activate all members of the ARF GTPase family (80, 81, 82) and are mutated in neuronal developmental disorders including X-linked intellectual disability with early onset epileptic encephalopathy (83, 84). The gene discussed is IQSEC2; the disease is X-linked intellectual disability.