OBJECTIVETo study the changes of minimal residual disease (MRD) in children with B cell acute lymphoblastic leukemia (B-ALL) of different genetic abnormalities.

METHODSBetween February 2004 and April 2013, 271 newly diagnosed B-ALL pediatric patients who had finished the induction chemotherapy were enrolled in the study. The characteristics of changes in MRD in patients with different genetic abnormalities on the 15th day and at the end of the induction therapy were analyzed.

RESULTSOn the 15th day of the induction chemotherapy, the MRD positive proportion in patients with hyperdiploid was higher on all the three cut-off levels of MRD≥0.1%, 1% and 10% compared to patients without hyperdiploid (P<0.05), but there was no significant difference in the MRD positive proportion on the three levels of MRD between the TEL-AML1-positive and TEL-AML1-negative groups (P>0.05). On the end of induction chemotherapy, there was no significant difference in the MRD positive proportion on the three levels of MRD between the patients with and without hyperdiploid (P>0.05), neither between the BCR-ABL-positive and negative groups. The MRD positive proportion in TEL-AML1-negative patients was significantly higher than in TEL-AML1-positive patients on all three levels of MRD (P<0.05). The MRD positive proportion on two levels of MRD≥0.01% and 0.1% in E2A-PBX1-negative patients was significantly higher than in E2A-PBX1-positive patients (P<0.05).

CONCLUSIONSChildren with B-ALL of different genetic abnormalities have different MRD levels during, and at the end of, induction therapy. The prognostic significance of MRD may be related to the genetic abnormalities.