This might either be due to uniparental disomy, selection pressure or to a related upstream mechanism that entails the epimutation on both alleles of DNMT3A. Notably, very high aberrant DNA hypermethylation was only observed in AML samples, but not in chronic myeloid leukemia or other myeloproliferative neoplasms. This evidence concerns the gene DNMT3A and acute myeloid leukemia.