This study aimed to examine serum levels of Th17-related cytokines (IL-17, IL-21, IL-22, IL-23) and chemokines (CCL2, CCL5, CCL20, CXCL10, IL-8) in schizophrenia patients compared to healthy controls and to explore their associations with symptom severity and laboratory parameters. This evidence concerns the gene IL21 and schizophrenia.