GRIK3 and major depressive disorder: The finding of an association with a locus on chromosome 1 (rs490647), which includes the glutamatergic kainate receptor GRIK3, is of considerable interest given that abnormalities of the glutamate system are implicated in the pathophysiology of MDD.55, 56, 57, 58, 59, 60 Furthermore, a recent glutamate receptor gene expression study in a large cohort of post-mortem subjects, including some individuals with MDD who had completed suicide, found GRIK3 to be the strongest predictor of suicide.43