The delta family of ionotropic glutamate receptors (iGluRs) consists of the glutamate δ1 (GluD1) and glutamate δ2 (GluD2) receptors. GluD1 is highly expressed in the inner hair cells of the organ of Corti4, diffusely expressed throughout the forebrain during development with high levels in the hippocampus during adulthood3. Deletion of GluD1 leads to a deficit in high frequency hearing in mice5. Genetic association studies have established the GRID1 gene, which codes for GluD1, is a strong candidate gene for schizophrenia, bipolar disorder, and major depressive disorder6. Copy number variation studies have also implicated GRID1 in autism spectrum disorder (ASD)7. In addition, GRID1 gene is localized to the 10q22–q23 genomic region which is a site for recurrent deletions associated with cognitive and behavioral abnormalities.