In SLE patients, there have been few studies that have explored the role of Th9 cells along with its related cytokine IL-9, and have indicated an increase in Th9 cells and IL-9 serum levels in SLE patients in comparison to healthy controls (Dantas et al., 2015; Ouyang et al., 2013), along with a positive correlation with SLEDAI (Ouyang et al., 2013). The gene discussed is IL9; the disease is systemic lupus erythematosus.