Identification of cytogenetic subclasses and recurring chromosomal aberrations in AML and MDS with complex karyotypes using M-FISH

Abnormalities in Chromosomes 5 and 7 in Myelodysplastic Syndrome and Acute Myeloid Leukemia

Chromosomes 5 and 7 are large chromosomes that contain close to 1,000 genes each. Deletions of the long arms or loss of the entire chromosome (monosomy) are common defects in myeloid disorders, particularly MDS and AML. Loss of material from either chromosome 5 or 7 results in haploinsufficiency of multiple genes, with some implicated in leukemogenesis. Abnormalities of one or both occur in up to 15% of MDS and AML cases and co-segregate in half of these. Generally, these chromosomal abnormalities are harbingers of adverse risk in both myeloid disorders. A notable exception is del(5q) in 5q- syndrome, a subtype of MDS. In this review, we describe the pathogenesis and genetic consequences of deletions in chromosomes 5 and 7. Furthermore, we provide an overview of current testing methodologies used in the assessment of these chromosomal defects in hematological malignancies and describe the disease associations and prognostic implications of aberrations in chromosomes 5 and 7 in both MDS and AML.

Cytogenetic profile of 1791 adult acute myeloid leukemia in India

BACKGROUND

Cytogenetic analysis continues to have an important role in the management of acute myeloid leukemia (AML) because it is essential for prognostication. It is also necessary to diagnose specific categories of AML and to determine the most effective form of treatment. Reports from South Asia are few because the availability of cytogenetic services is relatively limited.

METHODS

We performed a retrospective analysis of the cytogenetic findings in adults with AML seen consecutively in a single centre in India. The results were categorised according to the 2022 World Health Organisation (WHO), International Consensus Classification (ICC) and European LeukemiaNet (ELN) classifications.

RESULTS

There were 1791 patients aged 18-85 years (median age 42, 1086 males). Normal karyotypes were seen in 646 (36%) patients. The 1145 (64%) abnormal karyotypes comprised 585 (32.7%) with recurrent genetic abnormalities (RGA), 403 (22.5%) with myelodysplasia-related cytogenetic abnormalities (MRC), and 157 (8.8%) with other abnormalities. There were 567 (31.7%) patients with solitary abnormalities and 299 (16.7%) with two abnormalities. Among the 279 (15.6%) patients with ≥ 3 abnormalities, 200 (11.2%) had complex karyotypes (CK) as per the WHO/ICC and 184 (10.3%), as per the ELN definition. There were 158 (8.8%) monosomal karyotypes (MK). Patients with normal karyotypes had a higher median age (45 years) than those with abnormal karyotypes (40 years, p < 0.001), and those with ≥ 3 abnormalities (43 years), than those with fewer abnormalities (39 years, p = 0.005). Patients with CK (WHO/ICC) and monosomal karyotypes had a median age of 48 years. Those with RGA had a lower median age (35 years, p < 0.001) than MRC (46 years) or other abnormalities (44 years). The t(15;17) was the most common abnormality (16.7%),followed by trisomy 8 (11.6%), monosomy 7/del 7q (9.3%), t(8;21) (7.2%), monosomy 5/del 5q (6.7%) and monosomy 17/del 17p (5.2%).

CONCLUSION

Our findings confirm the lower age profile of AML in India and show similarities and differences with respect to the frequencies of individual abnormalities compared to the literature. The frequencies of the t(15;17), trisomy 8 and the high-risk abnormalities monosomy 7 and monosomy 5/del 5q were higher, and that of the inv(16), lower than in most reports.

Rare Ring Chromosome [r(15)]: Cytogenetic Abnormality in TP53-Mutated De Novo AML-M4 Masked as Gastrointestinal Bleed With Rapidly Progressing Hyperleukocytosis and Leukostasis

TP53-mutated (TP53m) acute myeloid leukemia (AML) comprises only 5-15% of de novo AML, associated with poor survival outcomes due to its resistance to conventional therapy. Ring chromosomes, an even more rare subset of genetic anomalies, occur in only 2% of cases. We report a unique case of de novo AML with both TP53 and ring chromosome anomalies leading to a catastrophic outcome in a 72-year-old male who initially presented with gastrointestinal bleeding (GIB) and urethral stone status post-cystoscopy with J-stent placement. He had no history of chemotherapy use, radiation, benzene exposure, or any other risk factors except for his age. He was noted to have pancytopenia, for which bone marrow biopsy, flow cytometry, and cytogenetic studies were done. Biopsy reported an interesting next-generation sequenced TP53-mutated AML, which correlates with a low rate of response to standard chemotherapy except for bone marrow transplants. Notably, with a complex aberration of 45 XY with multiple translocations (t), deletions (del), inversions (inv), derivative (der) breakpoints, aneuploidy, and rare ring and maker chromosomes, his case was complicated with rapid-onset and very severe hyperleucostasis, reflecting the prognostic value of this rare cytogenetic configuration. The patient expired within 48 hours of diagnosis, despite the urgent initiation of cytoreductive therapy and the mitigation of tumor lysis syndrome with Rasburicase. To the best of our knowledge, this is one of the first AML-M4 patients with rapid-onset leucostasis and the demise of next-generation sequences (NGS) in a de Novo AML patient with this rare complex combination.

Successful treatment of two relapsed patients with t(11;19)(q23;p13) acute myeloid leukemia by CLAE chemotherapy sequential with allogeneic hematopoietic stem cell transplantation: Case reports

The prognosis of patients with relapsed/refractory acute myeloid leukemia (R/R AML) is poor, with a 3-year overall survival rate of 10%. Patients with translocation (t)(11;19)(q23;p13) have a higher risk of relapse and there is no optimal regimen for these patients. The present study treated two young patients with t(11;19)(q23;p13) AML, who relapsed after one or two cycles of consolidation, with a salvage treatment consisting of sequential cladribine, cytarabine and etoposide (CLAE) and allogeneic hematopoietic stem cell transplantation (allo-HSCT). Both neutrophil and platelet engraftments were achieved within 15 days, and no severe transplant-related complications and graft-versus-host diseases were observed. Following allo-HSCT, both patients achieved complete hematologic and cytogenetic remission. Decitabine was used for the prophylaxis of relapse. The two patients remained alive and disease-free for 100 days following allo-HSCT. The results presented here suggest that CLAE regimen sequential with allo-HSCT may be effective in treating patients with R/R AML, with t(11;19)(q23;p13). However, further studies and a larger sample size are required to validate the effectiveness of this treatment regimen.

Identification of distinctive long noncoding RNA competitive interactions and a six-methylated-gene prognostic signature in acute myeloid leukemia with -5/del(5q) or -7/del(7q)

BACKGROUND

Acute myeloid leukemia (AML) with -5/del(5q) or -7/del(7q) has special clinical and biological characteristics, but its molecular mechanisms and risk stratification remain unknown.

METHODS

The RNA sequencing and DNA methylation of 23 patients with -5/del(5q) or -7/del(7q) and 128 patients with other subtypes of acute myeloid leukemia were obtained from The Cancer Genome Atlas (TCGA). The regulatory mechanisms of competitive endogenous RNA (ceRNA) network and DNA methylation on gene expression were explored. To find robust and specific risk stratification for this AML subtype, a prognostic model was established and evaluated through four independent data sets.

RESULTS

We identified 966 differentially expressed long noncoding RNA, 2274 differentially expressed genes, and 47 differentially expressed microRNAs, and constructed a ceRNA network. After the integrated analysis of differentially methylated and expressed genes, 19 genes showed the opposite trend between the methylation variation and gene expression. An six-methylated-gene prognostic signature which highly correlated with overall survival was established, and the performance was validated by leave-one-out cross validation method and permutation test. Furthermore, the excellent prognostic value of this model was supported by an independent cohort, while specificity of this model was validated by three independent data sets, suggesting it as a predictive classifier with high efficiency for distinguishing those with -5/del(5q) or -7/del(7q) from other AML subtypes.

CONCLUSIONS

The ceRNA network may provide new ideas for the diagnosis and treatment for patients with -5/del(5q) or -7/del(7q).The six-methylated-gene prognostic signature was a robust, specific, and clinically practical risk stratification for the outcome of patients with AML having -5/del(5q) or -7/del(7q).

Establishment of cell line with NK/NKT phenotype from myeloid NK cell acute leukemia

Acute Myeloid Leukemia (AML) is the most common malignancy in adults with a 5-year survival rate of 27% of the total affected population. For effective treatment and new drug discovery, cell lines are considered as a very important tool. Here we report an establishment of a continuous human cell line AML-004 with a hypo-diploid chromosome 44 and presence of both NK/NKT phenotypes. The cell line was isolated from the blood sample of myeloid NK cell acute leukemia patients and extensively characterized by flow cytometery, morphology, and cytogentic analysis. Cytotoxicity by standard chemotherapeutic drugs was also examined. As characterized by Giemsa staining, the predominant cell type in the culture had high nuclear/cytoplasmic ratio. Cytogenetic analysis revealed high chromosome instability and structural abnormalities confirming the source of cell line from a patient with AML. The karyotype of the isolated cells did not alter up to around 40 passages. These AML-004 cells lacked specific markers for B and T lymphoid cells, but expressed surface receptors for lymphoid/NK cells. Cells also lacked the presence of early progenitors. The proliferation of the isolated cells was inversely proportional to the IL-2 concentration confirming presence of NK phenotype. AML-004 was resistant against standard chemotherapeutic drugs excluding cisplatin. Thus, AML-004 cells provide a continuous source of human cells for designing novel therapies for patients with T-lymphoblastic leukemia/lymphoma.

Whole-arm translocation of der(5;17)(p10;q10) with concurrent TP53 mutations in acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS): A unique molecular-cytogenetic subgroup

Der(5;17)(p10;q10) is a recurrent but rare aberration reported in myeloid neoplasms (MNs). We report 48 such patients including 19 acute myeloid leukemia (AML) and 29 myelodysplastic syndrome (MDS), to characterize their clinicopathological features. There were 29 men and 19 women, with a median age of 61 years (range, 18-80). 62.5% patients had therapy-related diseases (t-MNs), 70.8% had multilineage dysplasia and 83.3% showed complex karyotypes. In 39 patients tested, FLT3, NPM1, CEBPA, KIT were all wild type and NRAS, KRAS, IDH1, APC, TET2 mutations were detected in single case(s) respectively. TP53 mutations were identified in 8 of 10 cases (80%) tested. Median disease-free survival (DFS) and overall survival (OS) were 3 and 10 months, respectively and did not differ between AML or MDS cases, or between de novo versus therapy-related cases, or between the groups with or without complex karyotypes. In 19 patients who achieved complete remission after chemotherapy, and in 9 patients who underwent stem cell transplantation, the OS was better (14 and 17.5 months, P = 0.0128 and P = 0.0086, respectively). The der(5;17)(p10;q10) represents a unique molecular-cytogenetic subgroup in t-MNs and, associated with complex karyotypes. TP53 inactivation, resulting from 17p deletion coupled with TP53 mutation, likely contributes to the poor clinical outcome of these patients.

Genomic Copy Number Variations in the Myelodysplastic Syndrome and Acute Myeloid Leukemia Patients with del(5q) and/or -7/del(7q)

The most common chromosomal abnormalities in myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML) are -5/del(5q) and -7/del(7q). When -5/del(5q) and -7/del(7q) coexist in patients, a poor prognosis is typically associated. Given that -5/del(5q) and/or -7/del(7q) often are accompanied with additional recurrent chromosomal alterations, genetic change(s) on the accompanying chromosome(s) other than chromosomes 5 and 7 may be important factor(s) affecting leukemogenesis and disease prognosis. Using an integrated analysis of karyotype, FISH and array CGH results in this study, we evaluated the smallest region of overlap (SRO) of chromosomes 5 and 7 as well as copy number alterations (CNAs) on the other chromosomes. Moreover, the relationship between the CNAs and del(5q) and -7/del(7q) was investigated by categorizing the cases into three groups based on the abnormalities of chromosomes 5 and 7 [group I: cases only with del(5q), group II: cases only with -7/del(7q) and group III: concurrent del(5q) and del(7q) cases]. The overlapping SRO of chromosome 5 from groups I and III was 5q31.1-33.1 and of chromosome 7 from groups II and III was 7q31.31-q36.1. A total of 318 CNAs were observed; ~ 78.3% of them were identified on chromosomes other than chromosomes 5 and 7, which were defined as 'other CNAs'. Group III was a distinctive group carrying the most high number (HN) CNAs, cryptic CNAs and 'other CNAs'. The loss of TP53 was highly associated with del(5q). The loss of ETV6 was specifically associated with group III. These CNAs or genes may play a secondary role in disease progression and should be further evaluated for their clinical significance and influence on therapeutic approaches in patients with MDS/AML carrying del(5q) and/or -7/del(7q) in large-scale, patient population study.

der(5;17)(p10;q10) is a recurrent but rare whole-arm translocation in patients with hematological neoplasms: a report of three cases

We report the cases of 3 patients with hematological malignancies and complex karyotypes involving der(5; 17) (p10;q10), which results in the loss of 5q and 17p. Although deletions of 5q and 17p are recurrent abnormalities in hematological disease, only about 20 cases harboring der(5; 17) (p10;q10) have been reported. We address the tumorigenesis and morphological characteristics of hematological malignancies involving der(5; 17)(p10;q10), along with a review of the literature.

MYC rearrangement involving a novel non-immunoglobulin chromosomal locus in precursor B-cell acute lymphoblastic leukemia

MYC rearrangement, a characteristic cytogenetic abnormality of Burkitt lymphoma and several subsets of other mature B-cell neoplasms, typically involves an immunoglobulin gene partner. Herein, we describe a case of precursor B-cell lymphoblastic leukemia harboring a MYC rearrangement with a novel non-immunoglobulin partner locus. The patient was a 4-yr-old Korean boy with ALL of the precursor B-cell immunophenotype. At the time of the second relapse, cytogenetic analyses revealed t(4;8)(q31.1;q24.1) as a clonal evolution. The MYC rearrangement was confirmed by FISH analysis. He died 3 months after the second relapse without achieving complete remission. To our knowledge, this is the first report of a case of MYC rearrangement with a non-immunoglobulin partner in precursor B-cell lymphoblastic leukemia.

Demonstration of microchimerism in pregnant sows and effects of congenital PRRSV infection

The presence of foreign cells within the tissue/circulation of an individual is described as microchimerism. The main purpose of the present investigation was to study if microchimerism occurs in healthy sows/fetuses and if porcine reproductive and respiratory syndrome virus (PRRSV) infection influences this phenomenon. Six dams were inoculated intranasally with PRRSV and three non-inoculated dams served as controls. Male DNA was detected in female fetal sera of all dams via PCR. Male DNA was also detected in the maternal circulation. Sex-typing FISH showed the presence of male cells in the female fetal organs and vice versa. PRRSV infection did not influence microchimerism, but might misuse maternal and sibling microchimeric cells to enter fetuses.

Identification of a novel recurrent 1q42.2-1qter deletion in high risk MYCN single copy 11q deleted neuroblastomas

Neuroblastoma is an aggressive embryonal tumor that accounts for ∼15% of childhood cancer deaths. Hitherto, despite the availability of comprehensive genomic data on DNA copy number changes in neuroblastoma, relatively little is known about the genes driving neuroblastoma tumorigenesis. In this study, high resolution array comparative genome hybridization (CGH) was performed on 188 primary neuroblastoma tumors and 33 neuroblastoma cell lines to search for previously undetected recurrent DNA copy number gains and losses. A new recurrent distal chromosome 1q deletion (del(1)(q42.2qter)) was detected in seven cases. Further analysis of available array CGH datasets revealed 13 additional similar distal 1q deletions. The majority of all detected 1q deletions was found in high risk 11q deleted tumors without MYCN amplification (Fisher exact test p = 5.61 × 10(-5) ). Using ultra-high resolution (∼115 bp resolution) custom arrays covering the breakpoints on 1q for 11 samples, clustering of nine breakpoints was observed within a 12.5-kb region, of which eight were found in a 7-kb copy number variable region, whereas the remaining two breakpoints were colocated 1.4-Mb proximal. The commonly deleted region contains one miRNA (hsa-mir-1537), four transcribed ultra conserved region elements (uc.43-uc.46) and 130 protein coding genes including at least two bona fide tumor suppressor genes, EGLN1 (or PHD2) and FH. This finding further contributes to the delineation of the genomic profile of aggressive neuroblastoma, offers perspectives for the identification of genes contributing to the disease phenotype and may be relevant in the light of assessment of response to new molecular treatments.

Unfavorable-risk cytogenetics in acute myeloid leukemia

Cytogenetic analysis at diagnosis is one of the most significant prognostic factors in acute myeloid leukemia (AML). AML patients with unfavorable-risk cytogenetic abnormalities account for 16-30% of younger adult patients and have poor response to standard treatment, with only 32-55% achieving a complete response. Overall survival is also extremely poor with only 5-12% patients alive at 5-10 years after diagnosis. Owing to the poor response in this subset of patients, risk-adapted treatment has been investigated. Allogeneic stem cell transplant has been shown to provide a survival benefit in patients with unfavorable-risk cytogenetic abnormalities in complement receptor 1. Other risk-adapted treatment strategies, such as reduced-intensity conditioning regimens prior to allogeneic stem cell transplant for older patients with AML, have also shown some survival benefit, without increasing treatment-related toxicities. Risk-stratification models that include cytogenetic abnormalities, as well as other molecular markers, are being developed to allow for individualized risk-adapted treatment for patients with AML. Prospective multicenter trials will be needed to validate these prognostic models.

A novel unbalanced whole-arm translocation der(3;10)(q10;q10) in acute monocytic leukemia

We describe here a novel unbalanced whole-arm translocation der(3;10)(q10;q10) in a 58-year-old man with acute monocytic leukemia. Bone marrow was massively infiltrated with 22.2% monoblasts, 55.4% promonocytes, and 5.6% monocytes. These monocytic cells were positive for myeloperoxidase and alpha-naphthyl butyrate esterase staining. Surface marker analysis revealed that they were positive for CD4, CD13, CD33, CD56, and HLA-DR but negative for CD14 and CD34. Chromosome analysis of the bone marrow cells showed 46,XY,+3,der(3;10)(q10;q10)[18]/46,XY[2]. Spectral karyotyping confirmed der(3;10)(q10;q10) as a sole structural abnormality. By acquisition of a normal chromosome 3 but not a chromosome 10, the der(3;10)(q10;q10) resulted in trisomy 3q and monosomy 10p. The +3,der(3;10)(q10;q10) is thought to play a crucial role in the pathogenesis of acute monocytic leukemia because of the gain of 3q or the loss of 10p.

Diagnostic challenges in the myelodysplastic syndromes: the current and future role of genetic and immunophenotypic studies

Myelodysplastic syndromes (MDS) comprise a clinically and pathologically diverse collection of hematopoietic neoplasms, most commonly presenting with peripheral cytopenias typically in the context of bone marrow hypercellularity. Mechanistically, at least in the early phases of the disease, this apparently paradoxical picture is primarily due to ineffective hematopoiesis, which is accompanied by a variety of morphologic abnormalities in hematopoietic cells. The identification of recurrent, clinically relevant cytogenetic defects in MDS has spurred the research of molecular mechanisms that contribute to its inception as well as to the development of heterogeneous subtypes. Although conventional cytogenetic analyses remain a diagnostic mainstay in MDS, the application of contemporary techniques including molecular cytogenetics, microarray technologies and multiparametric flow cytometry may ultimately reveal new diagnostic parameters that are theoretically more objective and sensitive than current morphologic approaches. This review aims to outline the role of genetic and immunophenotypic studies in the evaluation of MDS, including findings that may potentially influence future diagnostic classifications, which could refine prognostication and ultimately facilitate the growth of targeted therapies.

[Progresses on the methods of tumor chromosome aberration analysis]

Most cancers are known to be associated with chromosome aberration, and chromosome analysis is essential to understand the relationships between chromosome aberration and cancer. Here we briefly introduce several methods of chromosome aberration detection, including G-banding, fluorescence in situ hybridization (FISH), spectral karyotyping (SKY), multi-fluorescence in situ hybridization (M-FISH), cross-species color banding (Rx-FISH), comparative genomic hybridization (CGH)and Array comparative genomic hybridization (Array CGH).

An analysis of complex chromosomal aberrations in seven cases of myelodysplastic syndromes by M-FISH and whole chromosome painting

Complex chromosomal aberrations (CCAs) can be detected in a substantial proportion of myelodysplastic syndrome (MDS). Comprehensive analysis of the chromosomal rearrangements in these CCAs has been hampered by the limitations of conventional cytogenetics (CC). Multiplex fluorescence in situ hybridization (M-FISH) is a new generation FISH technique which allows simultaneous identification of all the 24 human chromosomes. So it is very useful in clarifying CCAs, identifying cryptic interchromosomal rearrangements and characterizing marker chromosomes. But it also has some limitations. We used M-FISH and whole chromosome painting (WCP) to accurately refine the CCAs revealed by R-banding CC in seven cases with MDS. The composition and origin of 6 kinds of marker chromosomes, nine kinds of chromosomes with additional material undetermined and five kinds of derivative chromosomes undefined by CC were defined after M-FISH analysis. Four kinds of cryptic translocations overlooked by CC were found on derivative chromosomes and previously normal appearing chromosomes. In addition, M-FISH revealed some nonrandom aberrations which most frequently involved chromosome 17 (5/7) and -5/5q-(4/7). Fluorescence flaring is a main factor leading to misinterpretations. Some misclassified and missed chromosomal aberrations by M-FISH were corrected by WCP. M-FISH is a powerful molecular cytogenetic tool in clarification of CCAs. Complementary WCP can further identify misclassified and missed chromosomal aberrations by M-FISH. CC in combination with molecular cytogenetic techniques including M-FISH and WCP can more precisely unravel CCAs.

Cytogenetic, molecular genetic, and clinical characteristics of acute myeloid leukemia with a complex karyotype

Patients with acute myeloid leukemia (AML) harboring three or more acquired chromosome aberrations in the absence of the prognostically favorable t(8;21)(q22;q22), inv(16)(p13q22)/t(6;16)(p13;q22), and t(15;17)(q22;q21) aberrations form a separate category - AML with a complex karyotype. They constitute 10% to 12% of all AML patents, with the incidence of complex karyotypes increasing with the more advanced age. Recent studies using molecular-cytogenetic techniques (spectral karyotyping [SKY], multiplex fluorescence in situ hybridization [M-FISH]) and array comparative genomic hybridization (a-CGH) considerably improved characterization of previously unidentified, partially identified, or cryptic chromosome aberrations, and allowed precise delineation of genomic imbalances. The emerging nonrandom pattern of abnormalities includes relative paucity, but not absence, of balanced rearrangements (translocations, insertions, or inversions), predominance of aberrations leading to loss of chromosome material (monosomies, deletions, and unbalanced translocations) that involve, in decreasing order, chromosome arms 5q, 17p, 7q, 18q, 16q, 17q, 12p, 20q, 18p, and 3p, and the presence of recurrent, albeit less frequent and often hidden (in marker chromosomes and unbalanced translocations) aberrations leading to overrepresentation of segments from 8q, 11q, 21q, 22q, 1p, 9p, and 13q. Several candidate genes have been identified as targets of genomic losses, for example, TP53, CTNNA1, NF1, ETV6, and TCF4, and amplifications, for example, ERG, ETS2, APP, ETS1, FLI1, MLL, DDX6, GAB2, MYC, TRIB1, and CDX2. Treatment outcomes of complex karyotype patients receiving chemotherapy are very poor. They can be improved to some extent by allogeneic stem cell transplantation in younger patients. It is hoped that better understanding of genomic alterations will result in identification of novel therapeutic targets and improved prognosis in patients with complex karyotypes.

EVI1 activation in blast crisis CML due to juxtaposition to the rare 17q22 partner region as part of a 4-way variant translocation t(9;22)

Background

Variant translocations t(9;22) occur in 5 to 10% of newly diagnosed CMLs and additional genetic changes are present in 60–80% of patients in blast crisis (BC). Here, we report on a CML patient in blast crisis presenting with a four-way variant t(9;22) rearrangement involving the EVI1 locus.

Methods

Dual-colour Fluorescence In Situ Hybridisation was performed to unravel the different cytogenetic aberrations. Expression levels of EVI1 and BCR/ABL1 were investigated using real-time quantitative RT-PCR.

Results

In this paper we identified a patient with a complex 4-way t(3;9;17;22) which, in addition to BCR/ABL1 gene fusion, also resulted in EVI1 rearrangement and overexpression.

Conclusion

This report illustrates how a variant t(9;22) translocation can specifically target a second oncogene most likely contributing to the more aggressive phenotype of the disease. Molecular analysis of such variants is thus warranted to understand the phenotypic consequences and to open the way for combined molecular therapies in order to tackle the secondary oncogenic effect which is unresponsive to imatinib treatment.

Childhood myeloid/natural killer precursor acute leukemia with novel chromosomal aberrations der(5)t(4;5)(q31;q31.3) and t(14;17)(q32;q23)

We report a unique case of childhood acute leukemia. The leukemia blasts had lymphoblastoid appearance and expressed CD33, CD13, CD34, CD4, CD7, and CD56. The morphology and immunophenotype were most consistent with myeloid/natural killer precursor acute leukemia. The blasts had a complex karyotype, including two chromosomal aberrations, der(5)t(4;5)(q31;q31.3) and t(14;17)(q32;q23), not previously described in childhood acute leukemia. The patient achieved morphological remission following myeloid-based leukemia therapy.

Fluorescence in situ hybridization analysis of 110 hematopoietic disorders with chromosome 5 abnormalities: do de novo and therapy-related myelodysplastic syndrome-acute myeloid leukemia actually differ?

A retrospective cytogenetic study of acute myeloid leukemias (AML) and myelodysplastic syndromes (MDS) was conducted by the Groupe Francophone de Cytogénétique Hématologique (GFCH) to evaluate the structural abnormalities of chromosome 5 associated with other chromosomal abnormalities, in particular of chromosome 7, in these pathologies. In all, 110 cases of AML/MDS were recruited based on the presence of chromosome 5 abnormalities under conventional cytogenetics and supplemented by a systematic fluorescence in situ hybridization study of chromosomes 5 and 7. The abnormalities of the long arm of chromosome 5 (5q) were deletions of various sizes and sometimes cryptic. The 5q abnormalities were associated with translocations in 54% of cases and were simple deletions in 46%. In 68% of cases, 5q deletions were associated with chromosome 7 abnormalities, and 90% of these presented a complex karyotype. Of the 110 patients, 28 had a hematopoietic disorder secondary to chemotherapy, radiotherapy, or both. Among 82 patients with de novo AML/MDS, 63 were older than 60 years. Chromosomal abnormalities often associated hypodiploidy and chromosome 5 and 7 abnormalities in complex karyotypes, features resembling those of secondary hemopathies. Systematic investigation of the exposure to mutagens and oncogenes is thus essential to specify the factors potentially involved in MDS/AML with 5q abnormalities.

Redefining monosomy 5 by molecular cytogenetics in 23 patients with MDS/AML

Deletion of the long arm of chromosome 5 [del(5q)] or loss of a whole chromosome 5 (-5) is a common finding, arising de novo in 10% of patients with myelodysplastic syndromes (MDS) or acute myeloid leukemia (AML) and in 40% of patients with therapy-related MDS or AML. We investigated by molecular cytogenetics 23 MDS/AML patients for whom conventional cytogenetics detected a monosomy 5. Monosomy 5 was redefined as unbalanced or balanced translocation and ring of chromosome 5. Loss of 5q material was identified in all 23 patients, but one. One copy of EGR1(5q31) or CSF1R(5q33-34) genes was lost in 22 of the 23 patients. Chromosome 5p material was a constant chromosomal component of derivative chromosomes or rings in all patients, but one. Sequential fluorescent in situ hybridization studies with whole chromosome paints and region-specific probes, used as a complement to conventional cytogenetic analysis, allow a better interpretation of karyotypes in MDS/AML patients.

Evaluation of recurring cytogenetic abnormalities in the treatment of myelodysplastic syndromes

Myelodysplastic syndromes (MDS) are clinically heterogeneous, but the presence of specific cytogenetic abnormalities can predict disease manifestations, provide a basis for prognosis, and direct treatment. Conventional cytogenetic analysis is instrumental in identifying chromosomal abnormalities in MDS and novel genetic methods may provide supplementary information. Treatment with lenalidomide was recently shown to be effective in MDS, particularly in those cases with del(5q), resulting in durable cytogenetic remission and hematological responses. In this paradigm, diagnosis of the del(5q) abnormality would be essential to predicting response to therapy.

GAB2 is a novel target of 11q amplification in AML/MDS

Chromosome arm 11q amplifications involving the mixed lineage leukemia gene (MLL) locus are rare but recurrent aberrations in acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS). We have recently shown that in addition to the MLL core amplicon, independent sequences in 11q23-24 and/or 11q13.5 are coamplified within the same cytogenetic markers in 90% and 60% of patients, respectively. Here we further narrow down the minimal amplicon in 11q13.5 to 1.17 Mb by means of semi-quantitative PCR and FISH analyses. The newly defined amplicon contains seven genes, including the GRB2-associated binding protein 2 (GAB2). Using real-time RT-PCR we show a significant transcriptional upregulation of GAB2 in the patients who have GAB2 coamplified with MLL. Thus, the adaptor molecule GAB2 that has already been shown to enhance oncogenic signaling in other neoplasias appears as a novel target of 11q amplification in AML/MDS.

Clinical, cytogenetic and molecular characteristics of 14 T-ALL patients carrying the TCRβ-HOXA rearrangement: a study of the Groupe Francophone de Cytogénétique Hématologique

Recently, we and others described a new chromosomal rearrangement, that is, inv(7)(p15q34) and t(7;7)(p15;q34) involving the T-cell receptor beta (TCRbeta) (7q34) and the HOXA gene locus (7p15) in 5% of T-cell acute lymphoblastic leukemia (T-ALL) patients leading to transcriptional activation of especially HOXA10. To further address the clinical, immunophenotypical and molecular genetic findings of this chromosomal aberration, we studied 330 additional T-ALLs. This revealed TCRbeta-HOXA rearrangements in five additional patients, which brings the total to 14 cases in 424 patients (3.3%). Real-time quantitative PCR analysis for HOXA10 gene expression was performed in 170 T-ALL patients and detected HOXA10 overexpression in 25.2% of cases including all the cases with a TCRbeta-HOXA rearrangement (8.2%). In contrast, expression of the short HOXA10 transcript, HOXA10b, was almost exclusively found in the TCRbeta-HOXA rearranged cases, suggesting a specific role for the HOXA10b short transcript in TCRbeta-HOXA-mediated oncogenesis. Other molecular and/or cytogenetic aberrations frequently found in subtypes of T-ALL (SIL-TAL1, CALM-AF10, HOX11, HOX11L2) were not detected in the TCRbeta-HOXA rearranged cases except for deletion 9p21 and NOTCH1 activating mutations, which were present in 64 and 67%, respectively. In conclusion, this study defines TCRbeta-HOXA rearranged T-ALLs as a distinct cytogenetic subgroup by clinical, immunophenotypical and molecular genetic characteristics.

Multicolor-FISH applied to resolve complex chromosomal changes in a case of T-ALL (FAB L2)

We report on a patient with a clinically diagnosed acute lymphoblastic leukemia (ALL) with partial unrecorded complex translocation events especially involving chromosomes 5, 9 and 18. At the GTG-band level the karyotype was abnormal in 20% of the analyzed cells. The complex karyotype was studied in more detail by spectral karyotyping (SKY) and multicolor banding (MCB) to characterize it in more detail. Thus, the karyotype could be described very accurately and in summary three different clones were detected, reflecting a high rate of karyotypic evolution in this patient.

Multiplex-FISH (M-FISH): technique, developments and applications

Multiplex FISH (M-FISH) represents one of the most significant developments in molecular cytogenetics of the past decade. Originally designed to generate 24 colour karyotyping, the technique has spawned many variations and an equally diverse range of applications. In tumour and leukaemia cytogenetics, the two groups that have been targeted represent both ends of the cytogenetic spectrum: those with an apparently normal karyotype (suspected of harbouring small rearrangements not detectable by conventional cytogenetics) and those with a complex aberrant karyotype (which are difficult to karyotype accurately due to the sheer number of aberrations). In research, mouse M-FISH provides a powerful tool to characterize mouse models of a disease. In addition, the ability to accurately karyotype single metaphases without selection makes M-FISH the perfect tool in chromosome breakage studies and for characterizing clonal evolution of tumours. Finally, M-FISH has emerged as the perfect partner for the developing genomic microarray (array CGH) technologies, providing a powerful approach to gene discovery.

del(6)(p23) in two cases of de novo AML--a new recurrent primary chromosome abnormality

OBJECTIVE

Previously, deletion 6p23 was generally reported in therapy-related secondary acute myeloid leukemia (AML) as part of complex karyotypes. In this report, we present two young adult patients with de novo AML-M2 and a terminal deletion 6p23 as a sole primary abnormality, confirmed by chromosome 6 specific subtelomeric probes.

METHODS

Two female patients 35 and 20 yr of age presented with anemia, but no bleeding, infections, lymphadenopathy or organomegaly. Morphological, immunophenotyping, chromosome and fluorescent in situ hybridization (FISH) analysis was performed on bone marrow aspirate cells.

RESULTS

A diagnosis of AML-M2 was confirmed in both patients by morphological and immunophenotyping studies. Chromosome analysis in case no. 1 showed deletion 6p23 in 20% of metaphases whereas in case no. 2 the deletion 6p23 was present in 100% metaphases. FISH analysis confirmed the deletion as terminal in both cases. The DEK oncogene at 6p23 in both cases was found not to be deleted.

CONCLUSION

To our knowledge, deletion 6p23 as a sole primary abnormality was reported in only one case. The common morphological, immunophenotypic, and cytogenetic features in our two patients strongly support a separate new entity of de novo AML with deletion 6p23.

Disclosure of candidate genes in acute myeloid leukemia with complex karyotypes using microarray-based molecular characterization

PURPOSE

To identify novel genomic regions of interest in acute myeloid leukemia (AML) with complex karyotypes, we applied comparative genomic hybridization to microarrays (array-CGH), allowing high-resolution genome-wide screening of genomic imbalances.

PATIENTS AND METHODS

Sixty AML cases with complex karyotypes were analyzed using array-CGH; parallel analysis of gene expression was performed in a subset of cases.

RESULTS

Genomic losses were found more frequently than gains. The most frequent losses affected 5q (77%), 17p (55%), and 7q (45%), and the most frequent genomic gains 11q (40%) and 8q (38%). Critical segments could be delineated to genomic fragments of only 0.8 to a few megabase-pairs of DNA. In lost/gained regions, gene expression profiling detected a gene dosage effect with significant lower/higher average gene expression levels across the genes located in the respective regions. Furthermore, high-level DNA amplifications were identified in several regions: 11q23.3-q24.1 (n = 7), 21q22 (n = 6), 11q23.3 (n = 5), 13q12 (n = 3), 8q24 (n = 3), 9p24 (n = 2), 12p13 (n = 2), and 20q11 (n = 2). Parallel analysis of gene expression in critical amplicons displayed overexpressed candidate genes (eg, C8FW and MYC in 8q24).

CONCLUSION

In conclusion, a large spectrum of genomic imbalances, including novel recurring changes in AML with complex karyotypes, was identified using array-CGH. In addition, the combined analysis of array-CGH data with gene expression profiles allowed the detection of candidate genes involved in the pathogenesis of AML.

Cytogenetic studies of a series of 43 consecutive secondary myelodysplastic syndromes/acute myeloid leukemias: conventional cytogenetics, FISH, and multiplex FISH

We report a series of 43 consecutive therapy-related myelodysplastic syndromes (t-MDS) or acute myeloid leukemias (t-AML) observed for 6 years. This series consisted of 26 women and 17 men, ages ranging from 9 to 85 years. These cases were classified into three groups according to the primary diagnosis. Conventional cytogenetic and fluorescent in situ hybridization (FISH)/ multiplex FISH (M-FISH) methods were used to analyze cytogenetic characteristics of secondary MDS/AML. The features of chromosomal abnormalities were linked to the nature of the therapy and protocols used. A considerable proportion of recurrent balanced translocations characterized t-AML secondary to therapy. FISH techniques showed that conventional cytogenetics often underestimated associated translocations; some deletions were in fact derivative chromosomes associated with deletions. After treatment for lymphomas and chronic myeloproliferative diseases, there were more complex unbalanced abnormalities than the control group. Compared to other series, recurrent translocations appeared to be more numerous (25%), probably reflecting an evolution of therapeutic modalities.

Complex chromosomal rearrangements in patients with chronic myeloid leukemia

During progression of chronic myeloid leukemia (CML) from the chronic to the accelerated phase and/or blast crisis, clonal evolution with nonrandom secondary aberrations such as +8, +Ph, i(17q), +19, -Y, +21, +17, and -7 is frequently observed. Complex chromosomal rearrangements (CCR) are rather rare, and the significance and frequency of different anomalies are poorly understood. The aim of this study was to determine the chromosomes and chromosomal regions which are involved in CCR during progression of the disease and the frequency of nonrandom changes. Conventional cytogenetics, FISH, and multicolor FISH (mFISH) were used to study karyotypes of 18 CML patients with CCR ascertained by G-banding. Most often involved in CCR were chromosomes 2 (x6); 3, 7, and 17 (x5); 1 and 4 (x4); and 5, 6, 11, and 12 (x3); regions 1q, 2q, 5q, 7p, and 17p; and breakpoints 17p11.2 (x3) and 7p15 (x2). There were no recurrent complex translocations. The present findings demonstrate the very high instability of the genome of malignant cells at the chromosomal level. Precise determination of breakpoints involved in CCR can give new dimension to the understanding of genetic mechanisms which play role in progression of malignant disease.

EVI1 is consistently expressed as principal transcript in common and rare recurrent 3q26 rearrangements

In contrast to the well-documented involvement of EVI1 in various 3q26 aberrations, the transcriptional status of EVI1 in rare recurrent or sporadic 3q26 chromosomal defects has remained largely unexplored. Moreover, in a recent report, the association between 3q26 alterations in myeloid proliferations and ectopic EVI1 expression was questioned. Therefore, we performed a detailed physical mapping of 3q26 breakpoints using a 1.3-Mb tiling path BAC contig covering the EVI1 locus and a carefully designed quantification of both EVI1 and MDS/EVI1 transcripts in 30 hematological malignancies displaying 3q26 aberrations. Cases included well-known rare, recurring chromosomal aberrations such as t(3;17)(q26;q22), t(2;3)(p21-22;q26), and t(3;6)(q26;q25), as well as 10 new sporadic cases. Extensive 3q26 breakpoint mapping allowed unequivocal and sensitive FISH detection of EVI1 rearrangements on both metaphases and interphase nuclei. Real-time quantitative PCR analyses indicated that typically both MDS1/EVI1 and EVI1, but not MDS1, were expressed in these malignancies, with EVI1 the primary transcript. In conclusion, we have demonstrated EVI1 involvement in numerous novel sporadic and recurrent 3q26 rearrangements. Our results underscore the feasibility of FISH as an adjunct to PCR for the identification of EVI1 deranged leukemias and identified EVI1 as the principal transcript expressed in these malignancies.

Analysis of complex chromosomal rearrangements in adult patients with MDS and AML by multicolor FISH

We analyzed complex chromosomal aberrations in 37 adult patients with myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML) using classical cytogenetic method, FISH with locus-specific probes, multicolor FISH (mFISH) and multicolor banding (mBAND). Unbalanced structural aberrations, leading to a gain or loss of chromosomal material, were frequently observed in bone marrow cells. In 30 patients (81.1%) loss or rearrangement of chromosome 5, 7 and/or 11 was found. The most frequent numerical change was trisomy 8 as expected (detected in six patients-16.2%) and the most frequent breakpoints 5q13, 5q33, 7q31, 10p12, 11q23, 12p13, 17p11 and 21q22 were determined.

Molecular cytogenetic study of 126 unselected T-ALL cases reveals high incidence of TCRbeta locus rearrangements and putative new T-cell oncogenes

Chromosomal aberrations of T-cell receptor (TCR) gene loci often involve the TCRalphadelta (14q11) locus and affect various known T-cell oncogenes. A systematic fluorescent in situ hybridization (FISH) screening for the detection of chromosomal aberrations involving the TCR loci, TCRalphadelta (14q11), TCRbeta (7q34) and TCRgamma (7p14), has not been conducted so far. Therefore, we initiated a screening of 126 T-cell acute lymphoblastic leukemia (T-ALL) and T-cell lymphoblastic lymphoma cases and 19 T-ALL cell lines using FISH break-apart assays for the different TCR loci. Genomic rearrangements of the TCRbeta locus were detected in 24/126 cases (19%), most of which (58.3%) were not detected upon banding analysis. Breakpoints in the TCRalphadelta locus were detected in 22/126 cases (17.4%), whereas standard cytogenetics only detected 14 of these 22 cases. Cryptic TCRalphadelta/TCRbeta chromosome aberrations were thus observed in 22 of 126 cases (17.4%). Some of these chromosome aberrations target new putative T-cell oncogenes at chromosome 11q24, 20p12 and 6q22. Five patients and one cell line carried chromosomal rearrangements affecting both TCRbeta and TCRalphadelta loci. In conclusion, this study presents the first inventory of chromosomal rearrangements of TCR loci in T-ALL, revealing an unexpected high number of cryptic chromosomal rearrangements of the TCRbeta locus and further broadening the spectrum of genes putatively implicated in T-cell oncogenesis.

Cytogenetic aspects of adult primary myelodysplastic syndromes: Clinical implications

Myelodysplastic syndrome (MDS) is a heterogeneous disease from the clinical, biological and morphological point of view. The pathogenesis of MDS is not well established and it appears to occur complex changes in the stem cell biology. Clonal chromosomal aberrations are found in 30-50% of primary MDS and no specific cytogenetic abnormality has as yet been defined. The chromosomal abnormalities are predominantly characterized by partial/total chromosomal losses or chromosomal gains. These chromosomal abnormalities include mainly -5/del(5q), -7/del(7q), del(11q), del(12p), del(20q), -Y, and +8. The role of cytogenetic analysis in the diagnosis, prognosis, taking treatment decisions and follow up of patients with MDS has been clearly defined. Despite its difficulties in obtaining for analysis high quality metaphases conventional cytogenetics continues to be the basic technique for cytogenetic evaluation of a MDS patient. Other molecular cytogenetic methods have been shown to be complementary, without replacing the information obtained with this technique. Further investigations with both conventional and molecular cytogenetics in relation to clinical features as well as other molecular methods will undoubtedly contribute to improve understanding of the underlying genetic events responsible for the development and evolution of MDS leading to more accurate classification and management of MDS patients.

Molecular cytogenetic profiling of complex karyotypes in primary myelodysplastic syndromes and acute myeloid leukemia

Complex chromosomal aberrations are present in < or =30% of patients with primary myelodysplastic syndrome (MDS) or acute myeloid leukemia (AML) and are associated with a poor prognosis. Specific alterations in complex karyotypes are difficult to define by conventional cytogenetics alone. To obtain a more comprehensive view of the recurrent aberrations, we performed spectral karyotyping (SKY) and fluorescence in situ hybridization (FISH) with selected probes on bone marrow samples from 17 patients with primary MDS and 3 with primary AML. All cases had chromosome 5 alterations. Two different types of 5q loss were identified: unbalanced translocations and interstitial deletions, or del(5q), each occurring in 10 patients. The most frequent additional chromosome aberrations were -3/-3p/-3q, -7/7q-, +8, 13q-, -16, 17p-, -18/18p-, -20/20q-, and +21q, each occurring in 25%. In the five cases with gain of 21q, involvement of the AML1 gene was excluded. Unbalanced 5q translocations occurred more often in combination with monosomy 3 and 7 and with gain of 21q, whereas del(5q) was associated more often with -1p and trisomy 8. A detailed analysis of specific breakpoints and deletions revealed recurrent involvement of specific chromosomal bands harboring known tumor suppressor genes or oncogenes. Analysis of large numbers of MDS and AML cases in a similar detailed manner with SKY and FISH will reveal whether new subgroups can be identified according to their genetic alterations. Correlation with clinical parameters may reveal the prognostic significance of these genetic subgroups.

Population-based demographic study of karyotypes in 1709 patients with adult Acute Myeloid Leukemia

Few large demographic studies of acute myeloid leukemia (AML) are derived from population-based registries. Demographic and karyotypic data were provided for AML cases from two regional leukemia registry databases in Scotland and the Northern Region of England. A population-based dataset was compiled, comprising 1709 patients aged >16 years (1235 North England/474 Scotland patients). The most common cytogenetic abnormalities involved chromosomes 5 and/or 7 (17%). Patients with the following abnormal chromosome 5/7 combinations: -5, del(5q), -5/-7 and del(5q)/-7 represented a significantly older population (P < 0.01, ANOVA). t(8;21) was the only 'favourable' karyotype found in older age. Karyotypic complexity varied within chromosome 5/7 combination groups; those containing -5, -5/-7, -5/del(7q), del(5q)/-7 or del(5q)/del(7q) combinations were significantly more frequently complex than those containing -7 and del(7q) (P < 0.01, chi2 test). Additional recurring cytogenetic abnormalities within complex karyotypes containing chromosome 5/7 combinations included (in order of frequency), abnormalities of chromosomes 17, 12, 3 and 18. Complex karyotypes not involving chromosomes 5 or 7 represented 30% of all complex karyotypes, occurred in younger patients than those involving chromosomes 5 and 7, and frequently included additional trisomy 8 (26%). In conclusion, we describe subgroups within adverse karyotypes, with different demographics, degree of complexity and additional chromosome abnormalities.

A FISH comparison of variant derivatives of the recurrent dic(17;20) of myelodysplastic syndromes and acute myeloid leukemia: Obligatory retention of genes on 17p and 20q may explain the formation of dicentric chromosomes

The dic(17;20) is a recurrent unbalanced translocation occurring rarely in myelodysplastic syndromes and acute myeloid leukemia. We have studied eleven cases with the dic(17;20) or a more complex derivative, all of which showed deletion of 17p and 20q material. The tumor suppressor gene TP53 was not always lost, supporting a more distal gene as the target of these 17p deletions. All derivatives could be interpreted as having initially been formed as a dicentric chromosome, those with a larger amount of material between the centromeres having undergone further rearrangement to stabilize the chromosome while retaining proximal 17p and proximal 20q material. We propose that critical sequences on both 17p and 20q proximal to the sites of deletion must be retained during the critical 17p and 20q deletions. This would explain the excess of dicentric chromosomes resulting from 17;20 translocation, and the apparent stabilization of the unstable derivatives by further rearrangements which preserve 17p and 20q material.

The myelodysplastic syndromes: diagnosis and treatment

The myelodysplastic syndromes (MDSs) are common, acquired, clinically challenging hematologic conditions that are characterized by bone marrow failure and a risk of progression to acute leukemia. These disorders can arise de novo, especially in elderly patients or, less often, as a consequence of prior chemotherapy or radiotherapy for an unrelated disease. The MDS classification systems were revised recently and updated. These refined classification and prognostic schemes help stratify patients by their risk of leukemia progression and death; this knowledge can help clinicians select appropriate therapy. Although many treatments for MDS have been proposed and evaluated, at present, only hematopoietic stem cell transplantation offers any real hope for cure, and no available therapy beyond general supportive care offers benefit to more than a minority of patients. However, recent clinical trials enrolling patients with MDS have reported encouraging results with use of newer drugs, including lenalidomide, decitabine, and darbepoetin alfa. Other exciting treatment regimens are being tested. Here, we present a contemporary, practical clinical approach to the diagnosis and risk-stratified treatment of MDS. We review when to suspect MDS, detail how to evaluate patients who may have a form of the condition, explain key features of treatments that are currently available in the United States, and summarize a general, common-sense therapeutic approach to patients with MDS.

A comparison of two contrasting recurrent isochromosomes 20 found in myelodysplastic syndromes suggests that retention of proximal 20q is a significant factor in myeloid malignancies

We compare two different isochromosomes of chromosome 20 in myelodysplastic syndromes (MDS): an isochromosome of the short arm of chromosome 20, idic(20)(q11), and an isochromosome of the long arm of a deleted chromosome 20, ider(20)(q10)del(20)(q11.2). The isochromosomes are of contrasting morphology, because opposite arms are duplicated, but they both show loss of the critical region at 20q12, as well as retention and duplication of the centromere and proximal long arm (20q11). We speculate that a region of proximal 20q is preferentially retained during deletions of the critical region in MDS and acute myeloid leukemia.

G-banding and molecular cytogenetic analyses of marginal zone lymphoma

We analysed the acquired chromosomal aberrations of 22 marginal zone lymphoma (MZL) patients by various genome-wide cytogenetic techniques, such as G-banding, multicolour fluorescence in situ hybridisation (M-FISH), cross-species colour banding (RxFISH), and comparative genomic hybridisation (CGH), as well as FISH with locus-specific probes. Patients with an abnormal chromosome 3 (n = 11), the most frequently rearranged chromosome, showed a shorter median survival than patients with a normal chromosome 3 (n = 11, 74 months vs. 219 months, P < 0.03). Four of five patients with nodal MZL had chromosome 3 abnormalities and patients with nodal MZL had a shorter median survival than patients in the other morphological subgroups of MZL (P < 0.003). CGH analysis showed only gains of chromosome material, namely of chromosome regions 3p12-25, 3q12-21, 3q23-28, 12q13-15, 12q22-24, 19p13 and 19q13 in two to four cases each (20-40%). In two MZL, the novel unbalanced translocation der(13)t(3;13)(q24;p11) was detected as the sole karyotypic rearrangement, indicating that gain of 3q24-qter could be an important event in the pathogenesis of these lymphomas. Another two cases showed, in addition to other abnormalities, a t(4;14)(p13;q32). Both these lymphomas had involvement of the IGH gene at 14q32, and one of them also of the RHOH/TTF gene at 4p13, which encodes a new member of the RHO protein subfamily.

Recurrent duplication of Xq27∼qter in hematological malignancies revealed by multicolor fluorescence in situ hybridization and multicolor banding

Multicolor fluorescence in situ hybridization (M-FISH) experiments were performed to determine the composition of abnormal complex karyotypes in 15 cases of hematological malignancy. Four cases were found to have unsuspected unbalanced X chromosome translocations, which resulted in the presence of extra X chromosome material. We determined the identity of the duplicated chromosome regions using the multicolor banding (mBAND) technique. Xq27-qter was duplicated in three of the four male cases with an X chromosome abnormality (i.e., in one third of male cases and one fifth of all cases). These preliminary results may point to the existence of a recurrent chromosome abnormality, either translocation at a specific Xq27 locus or duplication of Xq27-qter.

Acute myeloid leukemia with a complex aberrant karyotype is a distinct biological entity characterized by genomic imbalances and a specific gene expression profile

Acute myeloid leukemia (AML) with a complex aberrant karyotype is a distinct biological entity. It is characterized by: (1) a sharp increase in incidence above age 50; (2) a characteristic pattern of chromosomal gain and, especially, loss, that is, of 5q14q33, 7q32q35, and 17p13, translating into reduced expression of genes in these regions; (3) a unique gene expression pattern including up-regulation of genes involved in DNA repair; (4) a high incidence of TP53 deletions and/or mutations; and (5) an overall unfavorable prognosis. Further unraveling the biology of AML with a complex aberrant karyotype by gene expression profiling may provide deeper insights into the pathogenesis of as well as the reasons for chemoresistance in this AML subtype. These data may be the basis for developing targeted therapeutic strategies to increase the cure rate in patients with AML and a complex aberrant karyotype.