It has been recently shown that DNA methyl transferase overexpression is 
correlated with unfavourable prognosis in human malignancies while methylation 
deregulation remains a hallmark that defines acute myeloid leukemia (AML). The 
oncogenic transcription factor EVI1 is involved in methylation deregulation and 
its overexpression plays a major role for predicting an adverse outcome. 
Moreover, the identification of DNMT3A mutations in AML patients has recently 
been described as a poor prognostic indicator. In order to clarify relationship 
between these key actors in methylation mechanisms and their potential impact on 
patient outcomes, we analysed 195 de novo AML patients for the expression of 
DNMT3A, 3B (and its non-catalytic variant 3B(NC)) and their correlations with 
the outcome and the expression of other common prognostic genetic biomarkers 
(EVI1, NPM1, FLT3ITD/TKD and MLL) in adult AML. The overexpression of 
DNMT3B/3B(NC) is (i) significantly correlated with a shorter overall survival, 
and (ii) inversely significantly correlated with event-free survival and DNMT3A 
expression level. Moreover, multivariate analysis showed that a high expression 
level of DNMT3B/3B(NC) is statistically a significant independent poor 
prognostic indicator. This study represents the first report showing that the 
overexpression of DNMT3B/3B(NC) is an independent predictor of poor survival in 
AML. Its quantification should be implemented to the genetic profile used to 
stratify patients for therapeutical strategies and should be useful to identify 
patients who may benefit from therapy based on demethylating agents.