The key shared DEGs in RA and T2D including: CYP4F3, CXCR1/CXCR2, C4BPA, DEFA4, DEFA1, MMP8, MMP9, LTF, ARG1, MT2A, RBP1, MPO, MT2A, SNAI1 and MHC. The gene discussed is DEFA4; the disease is type 2 diabetes mellitus.