11q23 translocations (t(11q23)) are recurring cytogenetic abnormalities in both acute myeloid leukemia (AML) and acute lymphoblastic leukemia, involving the same gene, ALL1 (or MLL).
MLL rearrangement with t(6;11)(q15;q23) as a sole abnormality in a patient with de novo acute myeloid leukemia: conventional cytogenetics, FISH, and multicolor FISH analyses for detection of rare MLL-related chromosome abnormalities.
A partial nontandem duplication (PNTD) of mixed lineage leukemia (MLL) gene is described in B-cell acute lymphoid leukemia without structural cytogenetic abnormalities at 11q23 and 9p22.
A total of nine well-defined chromosome aberrations with fusion gene transcripts were selected: t(1;19) with E2A-PBX1, t(4;11) with MLL-AF4, t(8;21) with AML1-ETO, t(9;22) with BCR-ABL p190 and BCR-ABL p210, t(12;21) with TEL-AML1, t(15;17) with PML-RARA, inv (16) with CBFB-MYH11, and microdeletion 1p32 with SIL-TAL1.
All four cases demonstrated certain degrees of myelodysplasia and complex cytogenetic abnormalities with - 7/7q- and/or - 5/5q- or with 11q23 (KMT2A) rearrangement.
Among acute myeloblastic leukemia patients, frequency peaks were found for those with MLL/11q23 rearrangements (peak: first year), Down syndrome (peak: second to third year), or cytogenetic abnormalities other than translocations t(8;21), t(15;17), and inv(16)/t(16;16) (peak: first to third year).
An overall incidence of chromosomal anomalies, including t (9;22), MLL gene rearrangements, t (12;21), and numerical chromosomal anomalies of chromosomes 4, 10, 17 and 21 was found in 33 patients (65%).
Chromosome translocations involving the MLL gene on 11q23 are the most frequent chromosome abnormalities in secondary leukemias associated with chemotherapy employing etoposide, a topoisomerase II poison.
FISH analysis of nine cases with an MLL-specific yeast artificial chromosome (YAC) confirmed the cytogenetic abnormalities in two cases, clarified them in one, and did not detect six cases, including three MLL self-fusions, one case with a probable MLL-rearranged subclone not represented karyotypically, and twoMLL-AF6.
In acute lymphoblastic leukemia, besides age and white cell count at diagnosis, the cytogenetic abnormalities t(9;22)/BCR-ABL and t(4;11)/MLL-AF4 are important prognostic markers and are often included in the treatment stratification of patients with adult acute lymphoblastic leukemia.
In the second biopsy the hsr and MLL amplification appears as nonreciprocal translocation of multiple copies in the form of marked amplification of MLL on chromosome 16 in a background of increasing chromosomal aberrations.
Infant acute lymphoblastic leukemia (ALL) is frequently characterized by the t(4;11)(q21;q23)cytogenetic abnormality encoding the MLL/AF4 oncogene, increased HOX gene expression and a pro-B/monocytoid phenotype.
Masked MLL gene rearrangement was disclosed in the clinical course and sequential development of chromosome abnormality in a patient with therapy related acute myelogenous leukemia.
Moreover, 11 of 16 myeloid negative cases were also negative for any type of Bcr-Abl and MLL rearrangement, indicating that MPO mRNA positivity is not either invariably related to that chromosomal abnormality or necessarily associated with the presence of other myeloid differentiation features.
Our cases add two new translocations to the list of chromosomal anomalies involving the long arm of chromosome 11, and show that apparent translocation t(11q23) may involve loci and genes other than MLL.
Our results lend further support to the observation that the KMT2A-MAML2 fusion gene resulting from inv(11)(q21q23) is likely a recurrent cytogenetic abnormality in T-t-ALL and appears to be associated with pediatric cases.
Prognostic significance of additional cytogenetic aberrations in 733 de novo pediatric 11q23/MLL-rearranged AML patients: results of an international study.
Reciprocal chromosomal translocations involving the MLL gene at chromosome region 11q23 are recurring cytogenetic abnormalities in both de novo and therapy-related acute myeloid leukemia (AML) and in acute lymphoblastic leukemia.