GRIK4 and schizophrenia: The present study aimed to investigate the role of polymorphic variants of the genes for ionotropic receptors (GRIN2A, GRIN2B, GRIK4), metabotropic receptors (GRM3, GRM7, GRM8), and glutamate transporters (SLC1A2, SLC1A3, SLC17A7) in the development of tardive dyskinesia and its subtypes in patients with schizophrenia.