However, our case report and the two cases with Phelan–McDermid syndrome described above [48,49], collectively spur interest into exploring the possible therapeutic efficacy of lithium in larger samples of patients with autism and/or intellectual disability due to disruptive genetic variants affecting DLG2 [29] or other genes encoding postsynaptic glutamatergic scaffolding proteins [50]. This evidence concerns the gene DLG2 and Intellectual disability.