In systemic lupus erythematosus and rheumatoid arthritis, increased DNA demethylation and ERα expression were observed in the proximal promoter region of ERα gene transcription site, suggesting that ERα overexpression may be associated with systemic lupus erythematosus and rheumatoid arthritis.393 In female systemic lupus erythematosus CD4+ T cells, estrogen down-regulated DNMT1 expression and enhanced the global DNA hypomethylation. Here, ESR1 is linked to systemic lupus erythematosus.