PRF1 and systemic lupus erythematosus: Hypomethylation in the promoter region of some genes, such as Integrin Subunit Alpha L (ITGAL, Gene ID: 3683) (Yung et al., 1996; Lu et al., 2002), Perforin 1 (PRF1, Gene ID: 5551) (Lu et al., 2003; Kaplan et al., 2004), and members of Tumor Necrosis Factor Receptor Superfamily (TNFSF5 and TNFSF7, Gene ID: 959 and 970, respectively) (Oelke et al., 2004; Lu et al., 2005, 2007), were reported in lupus T cells.