CD4 and systemic lupus erythematosus: In line with findings in psoriatic disease, abnormal DNA methylation also characterizes other auto-immune/inflammatory disorders, such as systemic lupus erythematosus (SLE), where global DNA hypomethylation of CD4+ T cells has been associated with T cell autoreactivity in active lupus patients (Richardson, 1986; Zhang et al., 2013).