ESR1 and myelodysplastic syndrome: DNA methylation status or mutations in genes involved in DNA methylation (e.g., those encoding cyclin dependent kinase inhibitor 2B [CDKN2B], estrogen receptor 1 [ESR1], immunoglobulin superfamily member 4 [IGSF4] or Tet methylcytosine dioxygenase [TET2]) are candidates to influence the response to treatment with hypomethylating drugs in MDS [1, 11–13], but there is no unanimity between studies and some data do not support such associations [14–18].