In the analysis of genes with two damaging mutations unique to ASD cases, we identified two genes involved in the glutamatergic signaling pathway, the metabotropic glutamate receptor 3, GRM3, and glutamate receptor, ionotropic, kainate 4, GRIK4. Common variants in GRM3 have been shown to have association with ASD [66] while rare CNVs in GRIK4 have been implicated [11], and both genes have evidence for association in bipolar disorder [67] and schizophrenia [68, 69]. The gene discussed is GRIK4; the disease is bipolar disorder.