ESR1 and adenoma: One study found a positive association between red blood cell folate and hypermethylation of estrogen receptor 1 (ESR1)5 and secreted frizzled-related protein 1 (SFRP1) genes in the colon of subjects with adenoma (17), whereas another found no associations between markers of folate status and methylation in ESR1 and mut-L homolog 1 (MLH1) (18).