Allogeneic stem cell transplantation improves the outcome of adults with t(1;19)/E2A-PBX1 and t(4;11)/MLL-AF4 positive B-cell acute lymphoblastic leukemia: results of the prospective multicenter LALA-94 study.
The partial nontandem duplication of the MLL (ALL1) gene is a novel rearrangement that generates three distinct fusion transcripts in B-cell acute lymphoblastic leukemia.
However, rare cases of mature B-ALL with non-L3 morphology and MLL-AF9 fusion have been reported, and such cases are characterized by a rapid and aggressive clinical course.
These cases show that B-ALL with MLL rearrangement, especially the t(9;11) translocation, can express a 'mature' B-cell phenotype and may represent a distinct subset.
Up-regulation of miR-196b coincides with reduced DNA methylation at CpG islands in the promoter regions of miR-196b and the entire HOXA cluster in MLL-rearranged cases compared to in cases of non-MLL precursor B-cell acute lymphoblastic leukemia and normal bone marrow (P<0.05), suggesting an epigenetic origin for miR-196b over-expression.
Furthermore, the clinical features of this patient with the MLL-AF5q31 fusion transcript, characterized by the early pre-B phenotype (CD10(-)/CD19(+)) and poor outcome, were similar to those of patients having MLL-AF4 chimeric transcripts.