Acute monocytic leukemia (AML-M5b)

Four cases of acute myeloid leukemia with t(5;11)(q35;q12-13) are reported in the literature: two acute myeloblastic leukemia with differentiation (AML-M2) (Wang et al., 2006; de Oliveira et al., 2007), one acute myelomonocytic leukemia (AML-M4) (Itoh et al., 1999) and one acute monoblastic leukemia (AML-M5) (Leverger et al., 1988). No molecular characterization was performed in these cases but the NSD1 gene was shown not to be involved by fluorescent in situ hybridization in the AML-M2 case reported by Wang et al. (2006).

A 37-year-old man seen because of throat infection resistant to antibiotics, persistent fever and dyspnea.

Induction therapy and several salvage therapies failed to achieve complete remission followed by bone marrow transplantation.

Patient alive in complete remission 35 months following bone marrow transplantation.

The t(5;11)(q35;q12) involves two genes of which one, the NSD1 gene, has been already shown to form a fusion gene with NUP98 in the t(5;11)(q35;p15.1) (Jaju et al., 2001).

t(5;11)(q35;q12) is identified by banding cytogenetics.

To determine the position of the breakpoints on chromosomes 5 and 11, BACs located in the bands of interest were used as probes in FISH experiments. Analysis with RP11-99N22 showed that one signal hybridized to the normal chromosome 5, and the other split and hybridized to both der(5) and der(11). FISH with overlapping BACs identified a very small region of breakage in RP11-467L20. Analysis with RP11-467L20 showed that one signal hybridized to the normal chromosome 11, and the other split and hybridized to both der(11) and der(5). Co-hybridization with both BAC clones showed two fusion signals. RP11-99N22 contains the NSD1 gene and RP11-467L20 the FEN1 gene.