Chromosome 22 breakpoints in variant Philadelphia translocations and Philadelphia-negative chronic myeloid leukemia

The standard t(9;22)(q34;q11) found in Philadelphia (Ph) chromosome positive chronic myeloid leukemia (CML) involves a highly restricted (5.8 kb) chromosome 22 breakpoint cluster region (bcr), which results in the formation of a chimeric gene comprising exons from the 5' end of bcr and protooncogene c-abl coding sequences from chromosome 9. In a survey of 21 patients with hematologic and clinical features of CML we detected rearrangement of the chromosome 22 bcr by gene probe analysis in all cases, including 16 with a standard t(9;22), two with variant Ph translocations [t(10;22)(q26;q11);t(11;22)(p15;q11)], one with a complex Ph translocation [t(9;11;22)(q34;q13;q11)], one with a complex translocation and a masked Ph[t(9;14;22) (q34;q24;q11)], and one Ph-negative case with a t(1;9)(p32;q34). These observations further substantiate the suggestion that, despite karyotypic heterogeneity, a common underlying molecular lesion, the bcr-abl gene chimera, is involved in the disease pathogenesis of CML.     

Two novel translocations disrupt the RUNX1 gene in acute myeloid leukemia

Translocations involving 21q22 are commonly observed in both de novo and therapy-related acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS). They often result in the disruption of RUNX1 and give rise to fusion genes consisting of RUNX1 and different partner genes, which contribute to leukemogenesis. To date, at least 21 such translocations are known from the literature. Here we report two novel translocations involving the RUNX1 gene: t(1;21)(q12;q22) in a 53-year-old woman with AML-M5b and t(11;21)(q13;q22) in a 65-year-old man with AML-M2. The abnormalities revealed by R-banding karyotypic analysis were confirmed with interphase and metaphase fluorescence in situ hybridization (FISH), chromosome painting, and M-FISH.     

Variant Ph translocations in chronic myeloid leukemia

Variant translocations were found in eight of 142 consecutive patients with Ph-positive, chronic myeloid leukemia encountered in our laboratory during the last decade. Two patients had simple, two-way variant translocations: t(17;22)(p13;q11) and t(16;22)(q24;q11). Both of these patients had an additional translocation involving chromosomes #9: t(7;9)(q22;q34) and t(9;17)(q34;q21), respectively. Complex variant translocations were found in four cases: t(2;9;22)(p23q12;q34;q11), t(3;9;22)(p21;q34;q11), t(9;12;22)(q34;q13;q11q13), and t(13;17;22)(p11;p11q21;q11). In two cases, the only discernable cytogenetic aberration was del(22)(q11). A review of the chromosomal breakpoints involved in this series and in 185 cases of variant Ph translocations previously reported in the literature reveals that a disproportionately large number of breakpoints are located in light-staining regions of G-banded chromosomes. Furthermore, the breakpoints in simple variant translocations are more often located in terminal chromosomal regions, whereas, the breakpoints in complex translocations typically affect nonterminal bands. No obvious correlation was detected between variant Ph translocation breakpoints and either fragile sites, oncogene locations, or consistent chromosome breakpoints in other malignancies.     

Complex Ph translocations in chronic myeloid leukemia

Monosomy for chromosome 5 or a portion of the long arm is a common finding in acute nonlymphocytic leukemia (ANLL) and myelodysplastic syndrome (MDS), especially when the disorder is therapy related [1,2]. If only a portion of chromosome 5 is missing, the loss is usually accomplished by interstitial deletion of various bands, most frequently q12-14 to q31-33 [3]. Occasionally monosomy for 5q is the result of a translocation between chromosome 5 and another chromosome, with the loss of the derivative chromosome that contains 5q. A previously described unbalanced translocation involves chromosome 7: [der(5)t(5;7)(q11.2;p11.2)] and appears to be a recurring abnormality in these disorders [4]. We report here one case of therapy related MDS, one case of MDS which may be therapy related, and two cases of MDS with another "variant" 5q - abnormality, namely a derivative chromosome 3 composed of most of the short arm of chromosome 5 and the long arm of chromosome 3: [der(3)t(3;5)(?p11;?p11)].     

Therapy-related acute myeloid leukemia/myelodysplasia with balanced 21q22 translocations

The morphologic and immunophenotypic findings of 36 cases of 21q22 acute myeloid leukemia (AML) and myelodysplasia (MDS) were compared, including 14 de novo t(8;21) AMLs, 11 t(8;21) therapy-related AML/MDS cases, and 11 therapy-related AML/MDS cases with other 21q22 balanced translocations [t(n;21)]. Cases were evaluated for the presence of Auer rods, distinct chunky cytoplasmic blast cell granules, promyelocyte increase, cytoplasmic perinuclear clearing (hofs) of blast cells, eosinophil increase, andfeatures of associated trilineage dysplasia. Results of immunophenotyping studies for CD19, CD34, and CD56 expression were compared. Cases of de novo and therapy-related t(8;21) disease shared common morphologic features of chunky cytoplasmic granules, perinuclear hofs, and promyelocyte increases that were not seen consistently in the t(n;21) group of t-AML/MDS cases. Immunophenotypic similarities also were observed between the 2 t(8;21) groups. De novo and therapy-related t(8;21) disease, however, differed by the frequent presence of associated dysplasia in both t-AML/MDS groups, which was infrequent in the de novo t(8;21) group. Therapy-related AMI/MDS with t(8;21) shares characteristic morphologic and immunophenotypic features with de novo t(8;21) AML, but frequently also occurs with associated myelodysplastic changes, similar to other therapy-related acute leukemias.     

急性白血病、慢性髓细胞白血病及骨髓增生异常综合征患者染色体分析

目的探讨染色体分析在急性白血病（AL）、慢性髓细胞白血病（CML）及骨髓增生异常综合征（MDS）诊断及预后判断中的价值。方法采用骨髓细胞短期培养法,应用G、R显带技术对238例AL、CML及MDS患者进行染色体分析。结果56.30%的患者有染色体异常,其中数目异常占6.30%,结构异常占39.08%,复杂异常占10.92%;各组患者中CML组异常检出率最高,占总病例的34.87%;AL组染色体畸变最为复杂,累及除3,4,5,10及X以外的所有染色体,11例患者出现了特异性染色体畸变,与患者预后相关;CML加速/急变期出现了附加染色体异常;核型异常的MDS患者均检出了8三体,7例为单纯8三体,2例RAEB-T患者均为复杂异常。结论染色体检查对于疾病诊断与鉴别、指导临床治疗、判断预后等具有重要意义。     

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.     

Trisomy 22 in acute myeloid leukemia: a marker for myeloid leukemia with monocytic features and cytogenetically cryptic inversion 16

Trisomy 22 is an uncommon chromosomal abnormality in acute myeloid leukemia. Recent studies, however, have shown an association between trisomy 22 and acute myeloid leukemia with a monocytic component, and in particular, acute myelomonocytic leukemia with marrow eosinophilia. Furthermore, it has also been suggested that trisomy 22 was in fact only a secondary chromosomal change occurring in acute myeloid leukemia with inv(16). In this report, we analyze the morphological, cytogenetic, and molecular findings of three cases of acute myeloid leukemia with trisomy 22 but without cytogenetic evidence of inv(16). The results indicate a consistent association between trisomy 22 and inv(16), the latter being cytogenetically cryptic in some cases. This finding is of potential diagnostic and therapeutic significance.     

Jumping translocations of 11q in acute myeloid leukemia and 1q in follicular lymphoma

Jumping translocation is a rare cytogenetic aberration in leukemia and lymphoma, and its etiologic mechanisms are not clearly known. We report two cases with jumping translocations. One had follicular lymphoma and jumping translocations of 1q onto the telomeric regions of 5p, 9p, and 15q in three cell lines, co-existing with the specific translocation t(14;18)(q32;q21). The second case had acute myeloid leukemia (AML) and jumping translocations of 11q as the sole aberration, onto multiple derivative chromosomes in each of the abnormal cells. A total of 17 telomeric regions were seen as the recipients of 11q in this case, and 9q was always involved as one of the recipients in all abnormal cells. Fluorescence in situ hybridization (FISH) confirmed the identification of 11q material in the derivative chromosomes. While 1q has been the most common donor of acquired jumping translocations, this is the first report on jumping translocations of 11q. Different from all previously reported jumping translocations which involve only one recipient in each cell line and lead to a mosaic trisomy, multiple recipients in most of the abnormal cells in this case had led to a tetrasomy, or a pentasomy of 11q. The pattern of chromosome involvement as the recipients of 11q appears to show a continuing evolutionary process of jumping, stabilization, and spreading of the donor material into other chromosomes. Somatic recombinations between the interstitial telomeric or subtelomeric sequences of a derivative chromosome and the telomeric sequences of normal chromosomes are believed to be the underlying mechanism of jumping translocations and their clonal evolution.     

New recurrent balanced translocations in acute myeloid leukemia and myelodysplastic syndromes: Cancer and leukemia group B 8461

Acquired chromosome abnormalities in patients with acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS) are among the most valuable determinants of diagnosis and prognosis. In search of new recurrent balanced translocations, we reviewed the Cancer and Leukemia Group B (CALGB) cytogenetics database containing pretreatment and relapse karyotypes of 4,701 adults with AML and 565 with MDS who were treated on CALGB trials. We identified all cases with balanced structural rearrangements occurring as a sole abnormality or in addition to one other abnormality, excluded abnormalities known to be recurrent, and then reviewed the literature to determine whether any of what we considered unique, previously unknown abnormalities had been reported. As a result, we identified seven new recurrent balanced translocations in AML or MDS: t(7;11)(q22;p15.5), t(10;11)(q23;p15), t(2;12)(p13;p13), t(12;17)(p13;q12), t(2;3)(p21;p21), t(5;21)(q31;q22), and t(8;14)(q24.1;q32.2), and additionally, t(10;12)(p11;q15), a new translocation in AML previously reported in a case of acute lymphoblastic leukemia. Herein, we report hematologic and clinical characteristics and treatment outcomes of patients with these newly recognized recurrent translocations. We also report 52 unique balanced translocations, together with the clinical data of patients harboring them, which to our knowledge have not been previously published. We hope that once the awareness of their existence is increased, some of these translocations may become recognized as novel recurring abnormalities. Identification of additional cases with both the new recurrent and the unique balanced translocations will enable determination of their prognostic significance and help to provide insights into the mechanisms of disease pathogenesis in patients with these rare abnormalities. © 2012 Wiley Periodicals, Inc.     

Clonality analysis of cell lineages in acute myeloid leukemia with inversion 16

Bone marrow from 5 patients with acute myeloid leukemia with inversion 16, inv(16), was studied by a combination of fluorescence activated cell sorting (FACS) and fluorescence in situ hybridization (FISH) to establish the extent of cell-lineage involvement of inv(16). In all cases, interphase FISH demonstrated the inv(16) in 80-92% of blasts, monocytes, granulocytes, and a proportion of B-cells (21-41%). In contrast, inv(16) was not detectable above threshold levels in mature T-cells. The current study provides a direct evidence for the clonal involvement of myeloid lineage cells and B-lymphocytes and suggests that T-cells are not part of the malignant clone in this disease.     

Inversion-associated translocations in acute myelomonocytic leukemia with eosinophilia

Cytogenetic studies of three acute myelomonocytic leukemias with bone marrow eosinophilia (M4EO) revealed chromosome 16 inversion associated with additional abnormalities. The inverted chromosome 16 was involved in two patients. Fluorescence in situ hybridization (FISH) experiments with a YAC probe detecting inv(16) showed that the translocation breakpoints involving chromosome 16 did not implicate the inversion breakpoints. FISH can thus distinguish between true variant translocations and translocations with other breakpoints on chromosome 16 in M4EO.     

Unusual translocations and other changes in acute leukemia

We report three cases of ANLL and one case of ALL in which we found chromosome abnormalities not previously described. The first patient had a (9;11;16)(p22;q23;p13) translocation in the relapse after bone marrow transplantation. In the second case, a secondary leukemia following a Wilms' tumor, there was a single chromosome anomaly, an inversion of chromosome 13. The third case also presented an isochromosome 13q. In the fourth patient we observed a translocation between two achrocentric chromosomes, as in the third patient, but not of the Robertsonian type: t(21;21)(q22.1;q22.5).     

Chromosome painting in acute monocytic leukemia

An Alu polymerase chain reaction (PCR) probe specific for chromosome II prepared from the somatic cell hybrid JI was used to analyze karyotypes of eight patients with acute monocytic leukemia (AML-M5). Chromosome painting confirmed the t(9;II) in one patient and a der(I)t(I;6)t(6;II) in another and allowed the identification of a complex rearrangement involving chromosomes 9, 11, and 17, previously classified as del(II)(q23), in a third patient. An analysis of five patients with AML-M5 and a normal karyotype did not detect abnormalities of chromosome II. The usefulness of chromosome painting combined with in situ hybridization with probes previously located on particular chromosomes is emphasized. © 1993 Wiley-Liss, Inc.     

3'CBFbeta deletion associated with inv(16) in acute myeloid leukemia

Recent reports have shown that concomitant submicroscopic deletions can occur in association with chromosomal translocations/inversions in several leukemia subtypes. Detectable by fluorescence in situ hybridization (FISH), these losses of sequence include deletion of the 5' region of the ABL gene and the 3' region of BCR in chronic myeloid leukemia (CML) and acute lymphoblastic leukemia (ALL), as well as the 5' region of ETO in acute myeloid leukemia (AML) French-American-British type M2 associated with t(8;21), 3'MLL in AML and ALL, and 3' core-binding factor beta (CBFbeta) in AML associated with inv(16). While it has been widely reported that submicroscopic deletions of the derivative 9 in CML have an adverse prognostic impact, the clinical significance, if any, of deletions associated with t(8;21), inv(16)/t(16;16), or MLL rearrangement is yet to be determined. We analyzed a series of 39 patients diagnosed with AML who had cytogenetically detectable inv(16)/t(16;16) by using a FISH probe for the CBFbeta region to determine the incidence of the 3'CBFbeta deletion. Deletions were detected in three patients (8%), all associated with inv(16), bringing the number of cases reported so far to seven. The prognostic significance of this finding remains unclear.