PRF1 and systemic lupus erythematosus: The genome-wide methylation pattern has been studied by many authors and has revealed that in addition to classical methylation-sensitive related genes in SLE-CD4+ T cells including CD11a (ITGAL), perforin (PRF1), CD70 (TNFSF7), CD40 ligand (TNFSF5) and PP2Acα, reported by Zhang et al. [63], the tyrosine kinase gene (TNK2), the phosphatase gene (DUSP5) and type I IFN master regulator gene (IRF7) are also involved as reported by Coit et al. [64].