Growing evidence highlights immune dysregulation-particularly alterations in complement components C3 and C4-in the pathophysiology of schizophrenia; however, findings regarding peripheral complement levels and their clinical associations remain inconsistent.<h4>Method</h4>Thirty-nine patients with schizophrenia underwent clinical assessment using the Childhood Trauma Questionnaire (CTQ), the Positive and Negative Syndrome Scale (PANSS), the State-Trait Anxiety Inventory (STAI), and the Montreal Cognitive Assessment (MoCA). The gene discussed is C4A; the disease is schizophrenia.