As an immunomodulatory factors, IFN‐γ plays an important role in activation of macrophage, and abnormal expression of IFN‐γ has been reported to be associated with a variety of auto‐inflammatory and immune diseases, such as chronic periodontitis, IgA nephropathy and multiple sclerosis.13, 14, 15, 16. This evidence concerns the gene IFNG and immune system disorder.