GRIK4 encodes a kainate-type ionotropic glutamate receptor subunit (KA1) that functions as part of a cation-permeable ligand-gated ion channel. The protein cannot form functional channels independently but requires heteromeric assembly with other kainate receptor subunits (GRIK1, GRIK2, and GRIK3) to exhibit channel activity 1. KA1 protein is expressed in specific neuronal populations throughout the brain, including the cerebellum, frontal and parahippocampal cortices, and hippocampus, with particularly strong expression in CA3 and CA2 pyramidal cells and dentate gyrus granule cells 2. Functionally, GRIK4 plays a critical role in synaptic transmission and plasticity, with gene dosage alterations significantly affecting circuit output and behavior 3. Overexpression of GRIK4 enhances synaptic transmission, causing imbalanced inhibitory and excitatory activity that manifests as autism spectrum disorder-like behaviors including social impairment, enhanced anxiety, and depressive states 4. The gene shows clinical significance in psychiatric disorders, with specific polymorphisms associated with antidepressant treatment response in major depressive disorder 5 6 and copy number variations linked to autism 3. Additionally, a deletion variant in GRIK4 is associated with reduced bipolar disorder risk and increased protein expression 2.