No significant evidence of publication bias was found either in Begg's test or the Egger's test.<h4>Conclusion</h4>The present meta-analysis indicated that patients with schizophrenia did not show abnormal plasma levels of orexin-A.<h4>Systematic review registration</h4>https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021283455, identifier: CRD42021283455. The gene discussed is HCRT; the disease is schizophrenia.