Acute leukemia with t(10;11)(p11-p15;q13-q23)

A case of infantile acute lymphoblastic leukemia presenting with rearrangement of MLL at 11q23 and apparent insertion or translocation at 10p12

We report the case of an 11-month-old patient with a clinical diagnosis of infantile acute lymphoblastic leukemia and an MLL (11q23) rearrangement in 69% of nuclei, revealed with interphase fluorescence in situ hybridization (FISH). Routine chromosome analysis of the bone marrow showed a very subtle rearrangement involving the short arm of chromosome 10 and the long arm of chromosome 11 in the abnormal cells. To clarify the nature of this rearrangement, we hybridized the MLL break-apart probe to previously G-banded slides. The rearrangement was interpreted as a small inversion within the band 11q23, separating the 5' MLL from the 3' MLL region. This segment on the long arm of chromosome 11 containing the rearranged MLL locus was either inserted in or translocated to the short arm of chromosome 10 at approximately band 10p12. The inversion affecting MLL may have followed insertion or preceded it. Molecular characterization of this rearrangement was not possible, due to limited sample material. There have been previous reports of rearrangements of MLL with the MLLT10 (alias AF10) gene locus at 10p12, including an interstitial inverted insertion of 11q13q23 in one case and insertion of 11q14q23 at 10p12 in another. These both resulted in a large derivative chromosome 10 and transcription of an MLL/MLLT10 fusion product. To our knowledge, the novel and cryptic rearrangement detected in our patient has not been described previously. A follow-up study of the patient's bone marrow at the end of induction therapy showed no morphologic evidence of residual leukemia and both FISH and chromosome analyses were normal.

Monocytic leukemia with CALM/AF10 rearrangement showing mediastinal emphysema

The t(10;11)(p12-14;q14-21) is a non-random translocation that results in the fusion of CALM gene on chromosome 11 with AF10 gene on chromosome 10. This translocation is observed in acute myeloid leukemia, acute lymphoblastic leukemia, and lymphoblastic lymphoma. Here we report a patient with t(10;11) who was diagnosed with AML-M4. Reverse transcriptase-polymerase chain reaction (RT-PCR) assay revealed one type of CALM/AF10 and three types of AF10/CALM fusion transcripts. Sequencing analysis for these RT-PCR products determined the breakpoint in CALM at nucleotide (nt) 1926-1927 and in AF10 at nt 423-424. The latter breakpoint was the same as that identified in three monocytic cell lines carrying t(10;11). After achieving complete remission, the patient developed mediastinal emphysema during the course of consolidation therapy, possibly due to the necrosis of his mediastinal mass. Monocytic leukemias with CALM/AF10 fusion are frequently associated with mediastinal invasion. We need to pay special attention to such a complication, even if the chest X-ray is normal at presentation.

Molecular and fluorescence in situ hybridization analysis of a 10;11 rearrangement in a case of infant acute monocytic leukemia

Fluorescence in situ hybridization (FISH) analysis in a case of infant acute monocytic leukemia M5 revealed a complex rearrangement between chromosomes 10 and 11, leading to the disruption of the MLL gene. Using two painting probes for chromosomes 10 and 11 and a specific probe for the MLL gene localized on 11q23, we observed a paracentric inversion of the 11q13-q23 fragment translocated to 10p12. Molecular analysis showed that AF10 localized on 10p12 was the fusion partner gene of MLL in this rearrangement (10;11). This report underlined the usefulness of FISH and molecular techniques in identifying complex rearrangements.

Cytogenetic study of a patient with infant acute lymphoblastic leukemia using GTG-banding and chromosome painting

Numerical and structural chromosomal abnormalities occur in up to 90% of cases of childhood acute lymphoblastic leukemia (ALL). Two-thirds of these abnormalities are recurrent. The most common abnormalities are pseudodiploidy and t(1;19), occurring 40 and 5-6% of the time. Hyperdiploidy has the best prognosis, with an 80-90% 5-year survival. The 4;11 translocation has the worst prognosis, with a 10-35% 5-year survival. We report a patient with infant acute lymphoblastic leukemia and nonrecurrent rearrangements of chromosomes 10 and 11. Structural rearrangements between chromosomes 10 and 11 have been observed in 0.5% of all cases of childhood ALL with cytogenetic abnormalities. The identification of the apparently unique structural abnormalities was achieved using fluorescent in situ hybridization (FISH) with chromosome 10- and chromosome 11-specific painting probes as an adjunct to conventional cytogenetics. As is often the case, suboptimal preparations often preclude unequivocal identification of complex rearrangements by conventional banding techniques. The cytogenetic diagnosis of our patient was established as 46,XY, der(10)-t(10;11)(p15;q14)t(10;11)(q25;p11), der(11)t(10;11)(p15;q14)t(10;11)-(q25;p11). The benefits of FISH serve to increase the resolution of detection for chromosomal abnormalities and the understanding of the pathogenic mechanisms of childhood ALL.

Apparently unrelated clones shown by spectral karyotyping to represent clonal evolution of cryptic t(10;11)(p13;q23) in a patient with acute monoblastic leukemia

The accurate genetic classification of acute leukemia is of the utmost clinical importance for treatment stratification. In the present study, we report on a young girl with aggressive acute monoblastic leukemia (AML) (M5b) with skin, lymph node, and bone marrow involvement, in whom cytogenetic analysis revealed three clones with different secondary chromosomal changes. Two clones had the secondary +8 and del(9q) aberrations, with the der(11)t(1;11) in the second one; the third clone was apparently unrelated to the others, and had add(7)(p?21),-13,+22. Using the spectral karyotyping (SKY) technique, we found that all three clones originated from a common clone that harbored the hidden primary t(10;11)(p13;q23) or its derivatives, suggesting clonal evolution. The first clone had the balanced t(10;11), the second had its derivative, der(10)t(10;11), and the third had the other derivative, der(11)t(10;11). On fluorescence in situ hybridization (FISH), MLL gene splitting, with translocation of its centromeric portion to 10p, and deletion of its telomeric portion, was demonstrated. In conclusion, the detection of the very poor prognostic t(10;11) aberration in AML, was possible by complementing the traditional cytogenetic analysis with SKY and FISH.

Acute monocytic leukemia with a novel 10;11 rearrangement resolved by fluorescence in situ hybridization

Fluorescence in situ hybridization analysis in an adult with acute monocytic leukemia revealed the complex nature of a rearrangement between chromosomes 10 and 11, which resulted in disruption of the MLL gene. Using a combination of chromosome 10 and 11 paints, a 10 centromere-specific sequence, and a probe for the MLL locus at 11q23, the rearrangement was deduced to have involved a reciprocal translocation between chromosomes 10 and 11, followed by an inversion within the short arm of the derivative 10. To our knowledge, this novel rearrangement has not been described previously.

Molecular analysis of the CALM/AF10 fusion: identical rearrangements in acute myeloid leukemia, acute lymphoblastic leukemia and malignant lymphoma patients

The recurring translocation t(10;11)(p13;q14) which is found in acute myeloid leukemia (AML) and in acute lymphoblastic leukemia (ALL) results in the fusion of the putative transcription factor AF10 to CALM encoding a clathrin assembly protein. Previous studies using mainly fluorescence in situ hybridization (FISH) analysis have shown that the CALM/AF10 rearrangement is found in immature acute myeloid leukemia (AML) of subtype M0 and M1 and in T cell ALL. In this study we analyzed the CALM/AF10 and AF10/CALM fusion mRNAs in a series of three patients with AML, one patient with T-ALL and two patients with precusor T lymphoblastic lymphoma. In all six patients the breakpoint in CALM is at the 3' end of the coding region (nt1926/1927 or nt 2091/2092). Three breakpoints could be identified in AF10 (nt 588/589, nt 882/883 and nt 978/979). These data demonstrate that the CALM/AF10 fusions found in patients differ only slightly with respect to the portion of AF10 present and that there is no obvious difference between the fusions found in AML patients compared to those found in patients with lymphoid malignancies. Leukemia (2000) 14, 93-99.

Identification and molecular characterization of CALM/AF10fusion products in T cell acute lymphoblastic leukemia and acute myeloid leukemia

The t(10;11)(p12-p13;q14-q21) observed in a subset of patients with either acute lymphoblastic leukemia or acute myeloid leukemia has been shown to result in the fusion of AF10 on chromosome 10 with CALM (also named CLTH) on chromosome 11. AF10 was originally identified as a fusion partner of MLL in the t(10;11)(p12-p13;q23) observed in myeloid leukemia. CALM is a newly isolated gene, cloned as the fusion partner of AF10 in the monocytoid cell line, U937. In order to understand the relationship between MLL, AF10, CALM and the leukemic process, fluorescence in situ hybridization and reverse transcriptase polymerase chain reaction were used to study a series of nine leukemia patients with a t(10;11). Six had myeloid leukemia (AML-M0, AML-M1, AML-M4 and AML-M5) and three had T cell lymphoblastic leukemia. We identified four different CALM/AF10 fusion products in five patients and AF10/CALM reciprocal message in one. We conclude that fusion of CALM and AF10 is a recurring abnormality in both lymphoid and myeloid leukemias of various types including AML-M5, and that the breakpoints in the two types of leukemia do not differ. Our data indicate that the CALM/AF10 fusion product on the der(10) chromosome is critical to leukemogenesis. Leukemia (2000) 14, 100-104.

Consistent detection of CALM-AF10 chimaeric transcripts in haematological malignancies with t(10;11)(p13;q14) and identification of novel transcripts

The t(10;11)(p13-14;q14-21) is a rare but recurring translocation associated with acute lymphoblastic leukaemia (ALL) and acute myeloid leukaemia (AML). Recently the CALM gene was cloned from the t(10;11) breakpoint of U937 and fused to AF10, a putative transcription factor, which had been identified as one of the fusion partners of the MLL gene. In order to define the involvement of these genes in primary leukaemias and cell lines with t(10;11), we analysed the expression of fusion transcripts by reverse transcriptase-polymerase chain reaction (RT-PCR) in five patient samples including ALL, AML and lymphoblastic lymphoma, and three monocytic cell lines (P31/Fujioka, KP-Mo-TS and U937). The CALM-AF10 fusion transcript was detected in all samples; however, the AF10-CALM fusion was not detected in two patient samples and one cell line. In RT-PCR analysis there were six isoforms of the CALM-AF10 fusion transcripts and five of AF10-CALM fusion transcripts. We also detected novel transcripts in U937. Sequence analysis revealed that all these isoforms had in-frame junctions and that some of them resulted from alternative splicing at different exons of CALM and others from different breakpoints at CALM and/or AF10. There were at least two different breakpoints of CALM and three of AF10 gene. Our results suggest that the CALM-AF10 fusion gene is a constant feature and is involved in the pathogenesis of haematological malignancies with t(10;11)(p13-14;q14-21), showing various and often multilineage phenotypes. Thus, t(10;11) needs to be investigated by RT-PCR for identification of the genes involved.

Mixed-lineage leukemia with t(10;11)(p13;q21): an analysis of AF10-CALM and CALM-AF10 fusion mRNAs and clinical features

A fusion transcript of AF10 and CALM was isolated recently from the U937 cell line with t(10;11)(p13;q21). We performed reverse transcription-polymerase chain reaction and sequencing analysis on the t(10;11) leukemia samples obtained from four patients and one cell line, and we identified reciprocal fusion transcripts of AF10 and CALM in all the samples. The fusion transcripts in the five samples showed four different breakpoints in AF10 and three different breakpoints in CALM. In addition, the fusion transcripts in one sample showed a nucleotide sequence deletion in AF10, and those in two samples showed a nucleotide sequence deletion in CALM; the deletions were thought to be caused by alternative splicing. The variety of breakpoints and splice sites in the two genes resulted in five different-sized AF10-CALM mRNAs and in four different-sized CALM-AF10 mRNAs. Clinical features of 11 patients, including 6 of our own and 5 reported by others, in whom the fusion of AF10 and CALM was identified, are characterized by young age of the patients, mixed-lineage immunophenotype with coexpression of T-cell and myeloid antigens, frequent occurrence of a mediastinal mass, and poor clinical outcome.

Hematologic malignancies with the t(10;11) (p13;q21) have the same molecular event and a variety of morphologic or immunologic phenotypes

Previous studies described the t(10;11)(p13-14;q14-21) as a recurring translocation associated with T-cell acute lymphoblastic leukemia (ALL). This translocation has also been reported in monocytic leukemia or ALL with a very early pre-B phenotype. However, whether these cytogenetically similar translocations involve the same molecular breakpoint is unknown. Using fluorescence in situ hybridization (FISH) with a series of probes on 11q, we mapped the 11q breakpoint of the U937 cell line, which was derived from a patient with diffuse histiocytic lymphoma and was shown by FISH to have the t(10;11)(p13-14;q14-21). Subsequently, we identified a yeast artificial chromosome (YAC) clone, y960g8, that included the breakpoint on 11q. From this YAC, we isolated a PI clone, P91B1, that was split by the 10;11 translocation. We studied four patients with a t(10;11), one of whom had acute monocytic leukemia (AMoL), one had acute lymphoblastic leukemia (ALL), one had lymphoblastic lymphoma (LBL), and one had granulocytic sarcoma, by using FISH with y960g8 and P91B1. Y960g8 and P91B1 were split by the translocation in each patient. We showed that P91B1 included a recently identified gene, CALM (Clathrin Assembly Lymphoid Myeloid leukemia gene), and that AF10 was also rearranged in each patient by FISH when we used y807b3, which contains the AF10 gene. These findings indicate that hematologic malignant diseases with fusion of AF10 and CALM show various morphologic and immunologic phenotypes, suggesting that this fusion occurs in multipotential or very early precursor cells.