In leukemia, studies showed that DNMT3B was overexpressed in MDS, AML and CML patients.49,51,65 The DNMT3A expression level in AML patients was higher compared with ALL patients.65 However, another study found that DNMT3B expression was decreased in AML113 and B-CLL.33 Exploring the polymorphism C46359T in the DNMT3B promoter, Li et al. found different distributions of genotypes in different races and that the CT heterozygote was related to the pathogenesis of AL.166 Furthermore, DNMT3B mutations, polymorphisms, and expression were related to AML prognosis. The gene discussed is DNMT3B; the disease is B-cell chronic lymphocytic leukemia.