While reduced <i>GAD1</i> expression has been consistently reported in schizophrenia, findings regarding <i>GAD2</i> expression have been inconsistent.<h4>Methods</h4>In this study, we examined the expression of <i>GAD1</i>, <i>GAD2</i>, <i>SST</i>, and <i>PVALB</i> across three biological levels: postmortem brain tissue, peripheral blood samples, and patient-derived induced pluripotent stem cell (iPSC)-derived brain organoids, compared with healthy controls. Here, GAD2 is linked to schizophrenia.