It would be interesting to analyze the DNA methylation changes in some important subsets of B cells and CD4+ T cells, such as plasma B cells, regulatory B cells (Bregs), CD4+ cytotoxic T cells, Th2, follicular helper T cells (Tfh), and regulatory T cells (Tregs) in IgG4-RD patients in our future study. This evidence concerns the gene CD4 and immunoglobulin G4-related sclerosing disease.