Deletion of CBFB in a patient with acute myelomonocytic leukemia (AML M4Eo) and inversion 16

Acute myelomonocytic leukemia with bone marrow eosinophilia (AML M4Eo) is a subtype of AML with distinct morphological features. Inversion (16)(p13.1q22), t(16;16)(p13.1;q22), and del(16)(q22) are nonrandom abnormalities associated with AML M4Eo and a favorable prognosis, compared with the standard risk group for AML. Deletions of the proximal region of the MYH11 gene located at 16p13.1 have been detected in about 20% of patients with inv(16), with an undetermined effect on patient survival. We present the case of a patient with AML M4Eo and inversion 16 with a distal deletion of the CBFB gene at 16q22 detected with fluorescence in situ hybridization. To our knowledge, only one previous report of a similar deletion has appeared in the literature.     

Chromosome 16 inversion-associated translocations in acute myeloid leukemia elucidated using a dual-color CBFB DNA probe

We describe two cases of acute myelomonocytic leukemia with eosinophilia (AML-M4Eo) that were diagnosed with an inv(16)(p13q22) based on conventional cytogenetics (CC) and fluorescence in situ hybridization (FISH) technique using a chromosome 16p arm specific paint probe. Additional FISH analysis with a dual-color CBFB DNA probe showed that the 3' portion of the CBFB gene was translocated to chromosome 10p13 in the first patient and 1p36 in the other. These two cases indicate that some inv(16)(p13q22) identified by CC and FISH with chromosome arm-specific painting probe may represent cases of inversion-associated translocation. We suggest that all cases with inv(16)(p13q22) should be investigated by FISH with appropriate probes for a possible translocation of 16q22-->qter to another chromosome.     

A unique structural abnormality of chromosome 16 resulting in a CBF beta-MYH11 fusion transcript in a patient with acute myeloid leukemia, FAB M4

A 43-year-old female with a peripheral white cell count of 118.0 x 10(9)/L and 96% blasts was diagnosed with acute myeloid leukemia (AML), FAB M4. Cytogenetics, performed on a bone marrow sample, revealed the following abnormal karyotype: 46,XX,ins(16)(q22p13.1p13. 3). Fluorescence in situ hybridization (FISH) confirmed the inter-arm insertion using a probe for 16p. The result of this structural rearrangement was the fusion of CBF beta to MYH11 seen commonly in inv(16)(p13q22). The patient commenced high-dose intensive combination chemotherapy (big ICE; Idarubicin, Cytarabine, and Etopiside). Five days post chemotherapy, she developed febrile neutropenia. Despite broad spectrum intravenous antibiotics and antifungal therapy, the patient died at day nine post chemotherapy. This case demonstrates a previously unreported structural abnormality of chromosome 16 in a patient with AML M4, which represents a third mechanism to inv(16)(p13q22) and t(16;16)(p13q22) in producing the CBF beta-MYH11 fusion. CBF beta-MYH11 fusions masked by cryptic translocations at the cytogenetic level have been detected by FISH and PCR techniques. Due to the improved prognosis associated with CBF beta-MYH11 fusions compared to the standard risk group for AML, its detection remains important.     

inv(16)(p13q22) in chronic myelogenous leukemia in blast phase: a clinicopathologic, cytogenetic, and molecular study of five cases

Blast phase (BP) in chronic myelogenous leukemia (CML) frequently is accompanied by cytogenetic abnormalities in addition to t(9;22)(q34;q11.2). We describe 5 patients with CML in blast phase (CML-BP) in which t(9;22) and inv(16)(p13q22) were identified by conventional cytogenetics, with confirmation of BCR-ABL and CBFss-MYH11 by fluorescence in situ hybridization. The morphologic findings at the time of BP resembled de novo acute myeloid leukemia (AML) carrying inv(16)(p13q22), with abnormal eosinophils in the bone marrow and monocytosis in the peripheral blood in all cases. In 1 patient, inv(16)(p13q22) and abnormal eosinophils were detected in the bone marrow 2 months before CML-BP. The clinical course of these patients was similar to patients with CML-BP without evidence of inv(16)(p13q22). These cases illustrate that inv(16)(p13q22) is a form of cytogenetic evolution that rarely occurs in patients with CML at the time of BP. In this setting, unlike de novo AML, inv(16)(p13q22) in CML-BP is not associated with a favorable prognosis.     

Banding and molecular cytogenetic studies detected a CBFB-MYH11 fusion gene that appeared as abnormal chromosomes 1 and 16 in a baby with acute myeloid leukemia FAB M4-Eo

The acute myeloid leukemia (AML) subtype M4Eo occurs in 5% of all AML cases and is usually associated with either an inv(16)(p13.1q22) or a t(16;16)(p13.1;q22) chromosomal abnormality. At the molecular level, these abnormalities generate a CBFB-MYH11 fusion gene. Patients with this genetic alteration are usually assigned to a low-risk group and thus receive standard chemotherapy. AML-M4Eo is rarely found in infants. We describe clinical, conventional banding, and molecular cytogenetic data for a 12-month-old baby with AML-M4Eo and a chimeric CBFB-MYH11 fusion gene masked by a novel rearrangement between chromosomes 1 and 16. This rearrangement characterizes a new type of inv(16)(p13.1q22) masked by a chromosome translocation.     

Quantitative acute leukemia cytogenetics.

Using literature data on cytogenetic abnormalities in 3,612 cases of acute myeloid leukemia (AML) and 1,551-cases of acute lymphocytic leukemia (ALL), we have attempted to quantify the information value of finding the typical ALL- and AML-associated chromosome aberrations. Sensitivity, specificity, and predictive value of finding or not finding a given aberration were calculated for several diagnostic scenarios: for the differential diagnosis between ALL and AML when the patient is known to have acute leukemia, for the differential diagnosis among AML FAB subtypes in a patient with known AML, and for the differential diagnosis between ALL FAB subtypes in a patient with known ALL. The specificities were generally high, close to 1. The highest sensitivities in AML were found for +8, t(15;17)(q22;q11), t(8;21)(q22;q22), and -7 (all greater than 0.1), and in ALL for t(9;22)(q34;q11), t(4;11)(q21;q23), and +21 (again all greater than 0.1). In the AML subtypes, the highest sensitivities were 0.89 for t(15;17)(q22;q11) in M3, followed by 0.40 for t(8;21)(q22;q22) in M2, 0.30 for inv(16)(p13q22)/del(16)(q22)/t(16;16)(p13;q22) in M4, and 0.16 for t(9;11)(p21;q23) in M5. In the ALL subtypes, the highest sensitivities were 0.71 and 0.11 for t(8;14)(q24;q32) and t(8;22)(q24;q11), respectively, in L3, 0.23 for t(9;22)(q34;q11) in L2, and 0.18 and 0.13 for +21 and t(4;11)(q21;q23), respectively, in L1. The highest (1.0) positive predictive values in the AML versus ALL comparison were found for t(1;3)(p36;q21), inv(3)(q21q26), t(6;9)(p23;q34), t(7;11)(p15;p15), t(8;16)(p11;p13), t(8;21)(q22;q22), t(15;17)(q22;q11), and, as sole anomalies, for +4, +9, and +11. In the reverse comparison, ALL versus AML, positive predictive values of 1.0 were found for t(1;14)(p32-34;q11), dup(I)(q12-21q31-32), t(2;8)(p12;q24), t(8;14)(q24;q32), t/dic(9;12)(p11-12;p11-13), t(10;14)(q24;q11), and t(11;14)(p13;q11). Among the AML subgroups, the highest predictive values were: 1.0 for M3 if t(15;17), 0.91 for M2 if t(8;21), 0.86 for M4 if inv/del(16)/t(16;16), and 0.82 for M5 if t(9;11). Among the ALL subtypes, positive predictive values of greater than 0.8 were reached only for the L3-associated aberrations t(2;8) (1.0), t(8;14) (0.95), t(8;22) (0.87), and dup(I) (0.80). The highest negative predictive values were in AML 0.98 that the disease is not M3 if t(15;17) is not found, and in ALL 0.96 that the patient does not have L3 if a t(8;14) is not detected.     

Cohabiting t(12;22) and inv(3) primary rearrangements in an acute myelomonocytic leukemia (FAB M4) cell line

We describe the cytogenetic characterization of MUTZ-3, the first continuous cell line to be established from acute myelomonocytic leukemia (FAB M4) cells, exhibiting recurrent chromosomal rearrangements associated with this disease category. MUTZ-3 was established from peripheral blood taken at presentation from a 29-year-old male patient and carries the t(12;22)(p13.2;q11.2) associated with acute myelomonocytic leukemia (AMMoL), the inv(3)(q21.2q26.3) associated with multilineage acute myeloid leukemias (AML), and the inv(7)(p14q35) associated with ataxia telangiectasia (A-T). There was no evidence that the patient was an A-T heterozygote. The breakpoint on chromosome 22 mapped between 5'BCR and D22S39, consistent with the G-banding assignment. Both inversions were translocation-associated and may be further examples of an association previously described in AML FAB M4eo with inv(16). We suggest that the combination of inv(3)/t(3;3) with t(12;22) may represent a new, nonrandom association in AML. Genes Chromosom Cancer 16:144–148 (1996). © 1996 Wiley-Liss, Inc.     

Inversion of chromosome 16 with the Philadelphia chromosome in acute myelomonocytic leukemia with eosinophilia. Report of two cases.

Two cases are described with the rare combination of inv(16)(p13q22), strongly associated with acute myelomonocytic leukemia with eosinophilia, M4Eo, and the Philadelphia translocation, t(9;22)(q34;q11), hallmark of chronic myeloid leukemia (CML) and rarely found, (less than 1%), in acute nonlymphocytic leukemia. The patients were: case 1, a 9-year-old girl presenting with a white blood cell count (WBC) 42 x 10(9)/L with 32% blasts and bone marrow with blasts and eosinophil precursors consistent with M4Eo, and case 2, a 25-year-old man with WBC 34.7 x 10(9)/L with 13% blasts and bone marrow with features of M4Eo and basophilia. Both patients achieved remission but died following bone marrow transplantation in first remission (case 1) or in relapse (case 2). Cytogenetic findings were: case 1, at diagnosis, 46,XX,inv(16)(p13q22)(21)/46,XX,t(9;22) (q34;q11),inv(16)(8)/46,XX(10), and case 2, at diagnosis, 46,XY,t(9;22) (q34;q11),inv(16)(p13q22) (16) and in remission, 46,XY,t(9;22)(q34;q11) (1)/46,XY (24). Investigation of the breakpoint on 22 in case 1 with Southern blotting and the polymerase chain reaction demonstrated the presence of a p190 mRNA and a breakpoint typical of acute leukemia. Thus a diagnosis of M4Eo was supported by clinical and cytogenetic sequelae in each case; the Ph in case 1 was apparently secondary to inv(16), in case 2 the Ph probably preceded inv(16) in the etiology of the leukemia.     

t(10;16)(q22;p13) and MORF-CREBBP fusion is a recurrent event in acute myeloid leukemia

Recently, it was shown that t(10;16)(q22;p13) fuses the MORF and CREBBP genes in a case of childhood acute myeloid leukemia (AML) M5a, with a complex karyotype containing other rearrangements. Here, we report a new case with the MORF-CREBBP fusion in an 84-year-old patient diagnosed with AML M5b, in which the t(10;16)(q22;p13) was the only cytogenetic aberration. This supports that this is a recurrent pathogenic translocation in AML.     

Deletion of 16q11 is a recurrent cytogenetic aberration in acute myeloblastic leukemia during disease progression.

Abnormalities of chromosome 16 other than inv(16)(p13q22), t(16;16)(p13;q22), and del(16)(q22) have not been fully characterized in acute myeloblastic leukemia (AML) and myelodysplastic syndrome (MDS). We report here the first case of AML with del(16)(q11) as a sole abnormality. A 53-year-old woman was initially diagnosed as MDS, refractory anemia with excess of blasts in transformation with normal karyotype. After sixteen months, the disease progressed to overt AML-M1. Myeloblasts were positive for CD13, CD33, and CD34, but negative for HLA-DR. Chromosome analyses of the bone marrow cells showed 46,XX,del(16)(q11) in all metaphase spreads. Multicolor spectral karyotyping also confirmed that del(16)(q11) was not derived from a cryptic translocation, but a simple deletion. Our results, together with three previously reported cases, suggest that del(16)(q11) may be one of the recurrent aberrations in AML and that it could be associated with clonal evolution or disease progression.     

Translocation (8;18;16)(p11;q21;p13). A new variant of t(8;16)(p11;p13) in acute monoblastic leukemia: case report and review of the literature

A complex three-way t(8;18;16)(p11;q21;p13) was detected in a 15-month-old patient with acute myeloid leukemia (AML). The patient had typical clinical manifestation and bone marrow features of AML subtype M5b associated with t(8;16)(p11;p13). Therefore, we believe that the t(8;18;16) is a new variant of t(8;16) related to AML M4/M5. We also review other t(8;16)(p11;p13) variants reported in the literature.     

Chronic myelomonocytic leukemia with t(7;11)(p15;p15) and NUP98/HOXA9 fusion

We have recently cloned the inv(8)(p11q13) in a patient with acute myeloid leukemia (AML), and demonstrated a fusion between the MOZ and TIF2 genes at 8p11 and 8q13, respectively. We have partially characterized a further case of AML with the same karyotypic abnormality. Rearrangements were detected by Southern blotting with a TIF2 probe that was close to the breakpoint in the original inv(8) case and with a MOZ probe corresponding to the breakpoint cluster region in the t(8;16) (p11;p13). These findings indicate the existence of breakpoint cluster regions within both genes and demonstrate that the MOZ-TIF2 fusion is consistently associated with the inv(8)(p11q13).     

Acute myelomonocytic leukemia with inv(16)(p13q22) complicating Philadelphia chromosome positive chronic myeloid leukemia.

The reciprocal translocation (9;22)(q34;q11) is highly characteristic of chronic myeloid leukemia (CML) and the pericentric inversion inv(16)(p13q22) is almost only found in acute nonlymphocytic leukemia of the myelomonocytic subtype (ANLL M4). Only twice before have an inv(16) and a t(9;22) been found in the same cells, and both times the patients seemed to have de novo ANLL M4. We describe the case of a 21-year-old man who in July 1986 presented with a clinically and hematologically classic chronic phase CML. Treatment with busulfan led to no improvement; instead in September 1986 he developed blast crisis with ANLL M4Eo morphology. He was now cytogenetically examined and the karyotype 45,X,-Y,t(9;22)(q34;q11),inv(16)(p13q22) was found. Southern blot analysis of the bone marrow DNA sampled at this time revealed a standard rearrangement in the 3' end of the M-bcr. Intensive cytostatic treatment caused cytopenia followed by complete hematologic, clinical, and cytogenetic reversal to chronic phase CML, so that in January 1987 the bone marrow karyotype was 46,XY,t(9;22)(q34;q11). Persistent splenomegaly was treated with splenectomy, and a chloroma of the skin was removed by irradiation. In March 1987 he received an allogeneic bone marrow transplant. Since then his only medical problem has been mild graft-versus-host disease; he is well and is working full time as a blacksmith.     

Comparative analysis of genes regulated in acute myelomonocytic leukemia with and without inv(16)(p13q22) using microarray techniques, real-time PCR, immunohistochemistry, and flow cytometry immunophenotyping.

Acute myeloid leukemia with inv(16)(p13q22), also known as M4Eo, is a distinct type of leukemia with characteristic clinicopathologic and cytogenetic features. Patients with M4Eo have monocytosis, high blast counts, and abnormal bone marrow eosinophils that contain large basophilic granules. The inv(16)(p13q22) or, less commonly, the t(16;16)(p13;q22) causes fusion of the CBFbeta gene at 16q22 and the MYH11 gene at 16p13, creating the novel chimeric protein CBFbeta-MYH11. To understand the underlying molecular mechanisms unique to M4Eo biology, we determined the gene expression profile of M4Eo cases by using cDNA and long oligonucleotide microarrays. Cases of acute myelomonocytic leukemia without CBFbeta-MYH11 (M4) acted as our control. We found that in the gene expression profile of M4Eo, NF-kappaB activators and inhibitors were upregulated and downregulated, respectively, suggesting that the NF-kappaB signaling pathway is activated at a higher level in M4Eo than in acute myelomonocytic leukemia M4. In addition, the gene expression profile of M4Eo indicates high cell proliferation and low apoptosis. We used real-time PCR, immunohistochemistry, and flow cytometry immunophenotyping to confirm some of our microarray data. These findings most likely represent the functional consequences of the abnormal chimeric protein CBFbeta-MYH11, which is unique to this disease, and suggest that NF-kappaB is a potential therapeutic target for treating M4Eo patients.     

CBFB and MYH11 in inv(16)(p13q22) of acute myeloid leukemia displaying close spatial proximity in interphase nuclei of human hematopoietic stem cells

To gain a better understanding of the mechanism of chromosomal translocations in cancer, we investigated the spatial proximity between CBFB and MYH11 genes involved in inv(16)(p13q22) found in patients with acute myeloid leukemia. Previous studies have demonstrated a role for spatial genome organization in the formation of tumorigenic abnormalities. The nonrandom localization of chromosomes and, more specifically, of genes appears to play a role in the mechanism of chromosomal translocations. Here, two-color fluorescence in situ hybridization and confocal microscopy were used to measure the interphase distance between CBFB and MYH11 in hematopoietic stem cells (HSCs), where inv(16)(p13q22) is believed to occur, leading to leukemia development. The measured distances in HSCs were compared with mesenchymal stem cells, peripheral blood lymphocytes, and fibroblasts, as spatial genome organization is determined to be cell-type specific. Results indicate that CBFB and MYH11 are significantly closer in HSCs compared with all other cell types examined. Furthermore, the CBFB-MYH11 distance is significantly reduced compared with CBFB and a control locus in HSCs, although separation between CBFB and the control is ～70% of that between CBFB and MYH11 on metaphase chromosomes. HSCs were also treated with fragile site-inducing chemicals because both the genes contain translocation breakpoints within these regions. However, treatment with fragile site-inducing chemicals did not significantly affect the interphase distance. Consistent with previous studies, our results suggest that gene proximity may play a role in the formation of cancer-causing rearrangements, providing insight into the mechanism of chromosomal abnormalities in human tumors.