A novel t(2;10)(q31;p12) balanced translocation in acute myeloid leukemia

Abstract

We describe a case of acute myeloid leukemia M5 showing a balanced t(2;10) (q31;p12) translocation. This has never been described before as the sole cytogenetic abnormality in a bone marrow cell clone at onset. Using fluorescence in situ hybridization with properly designed bacterial artificial chromosome probes, we mapped the breakpoint regions on both derivative chromosomes 2 and 10: der(2) and der(10), respectively. The MPP7 gene, disrupted by the breakpoint on chromosome 10, was juxtaposed upstream of both HNRNA3 and NFE2L2 genes on chromosome 2, without the formation of any fusion gene. Using real-time quantitative polymerase chain reaction, we tested the possible disregulation of any of the breakpoint-associated genes as a consequence of the translocation, but we found no statistically significant alteration. Considering the potential role of this clonal cytogenetic abnormality in leukemogenesis, we speculate that this translocation could have an impact on additional genes mapping outside the breakpoint regions. However, the limited amount of RNA material available prevented us from testing this hypothesis in this present case.

Keywords: FISH; HNRNA3; MPP7.; NFE2L2; acute myeloid leukemia; chromosome; translocation.

Figure 1

A) Left: Fluorescence in situ hybridization (FISH) results obtained with bacterial artificial chromosome clones delimiting the breakpoint regions on der(2) and der(10). Right: Maps of the breakpoint regions in chromosome bands 2q31.2 (top) and 10p11.23 (bottom), according to the latest release of the UCSC Human Genome Browser (GRCh37/hg19) (February 2009). Genes are indicated by yellow bars. The reported clones have the same color code as the FISH image on the left. B) Expression analyses of exons 6 and 14 of MPP7 (red bars), exon 5 of HNRNPA3 (green bar), and exon 4 of NFEL2L2 (yellow bar) evaluated by real-time quantitative polymerase chain reaction, in the present case [t(2;10)], 4 control akute myeloid leukemia (AML) M5 samples, the mean Ct value of the controls (mean value), and normal bone marrow. The results showed comparable genes transcriptional levels in the patient with t(2;10) compared with the mean Ct value of the 4 M5 AML controls.