As no known studies have specifically examined genome-wide DNA methylation patterns of miRNA encoding genes in breast tumors from AA populations, and there is a clear pattern of ER-subtype differences (Fig 1), in the current study, we focused on analyses to identify differentially methylated loci (DML: |delta β|≥0.10; FDR<0.05) between ER- and ER+ tumors in AA and EA women, separately. The gene discussed is ESR1; the disease is breast neoplasm.