The analysis results showed that the levels of RF_IgA, RF_IgG, and RF_IgM in the RA combined with DM group were not significantly different from those in non-DM RA patients (U = 0.213, P = 0.832; U = 0.696, P = 0.487; U = 1.164, P = 0.245). This evidence concerns the gene CD40LG and rheumatoid arthritis.