These results suggest that the increased risk of developing diabetes conferred by the TYK2 promoter variant may be due to reduced TYK2 promoter activity accompanied by the decreased expression of the TYK2 gene and ISGs, while increased expression level of JAK1 gene on IFN stimulation in patients with TYK2 promoter variant may play a complementary role for the deteriorated TYK2 gene expression to maintain ISGs responses. The gene discussed is TYK2; the disease is diabetes mellitus.