Rare recurring balanced chromosome abnormalities in therapy-related myelodysplastic syndromes and acute leukemia: report from an international workshop

Acute myeloid leukemia with rare recurring translocations-an overview of the entities included in the international consensus classification

Two different systems exist for subclassification of acute myeloid leukemia (AML); the World Health Organization (WHO) Classification and the International Consensus Classification (ICC) of myeloid malignancies. The two systems differ in their classification of AML defined by recurrent chromosomal abnormalities. One difference is that the ICC classification defines an AML subset that includes 12 different genetic abnormalities that occur in less than 4% of AML patients. These subtypes exhibit distinct clinical traits and are associated with treatment outcomes, but detailed description of these entities is not easily available and is not described in detail even in the ICC. We searched in the PubMed database to identify scientific publications describing AML patients with the recurrent chromosomal abnormalities/translocations included in this ICC defined patient subset. This patient subset includes AML with t(1;3)(p36.3;q21.3), t(3;5)(q25.3;q35.1), t(8;16)(p11.2;p13.3), t(1;22)(p13.3;q13.1), t(5;11)(q35.2;p15.4), t(11;12)(p15.4;p13.3) (involving NUP98), translocation involving NUP98 and other partner, t(7;12)(q36.3;p13.2), t(10;11)(p12.3;q14.2), t(16;21)(p11.2;q22.2), inv(16)(p13.3q24.3) and t(16;21)(q24.3;q22.1). In this updated review we describe the available information with regard to frequency, biological functions of the involved genes and the fusion proteins, morphology/immunophenotype, required diagnostic procedures, clinical characteristics (including age distribution) and prognostic impact for each of these 12 genetic abnormalities.

Infant Acute Leukemia

Infant acute leukemia is a rare but aggressive disease. Although infant acute leukemia is cytologically and histologically similar to acute leukemia seen in older children and adults, it displays unique and characteristic clinical and genetic characteristics. The features, as well as the extremely young age of the patients, present multiple challenges for treatment. This review focuses on the unique pathology of acute leukemia of infancy, including the genetic characteristics that are specific for these diseases.

Therapy-related B-lymphoblastic leukemia associated with Philadelphia chromosome and MLL rearrangement: Single institution experience and the review of the literature

Therapy related acute lymphoblastic leukemia (t-ALL) of B cell origin is rare and constitutes approximately 2% of all ALL. Previously compiled data on the complete cytogenetic analysis of 48 t-B-ALL cases suggested that MLL rearrangement at 11q23 gene locus is the most common abnormality. Philadelphia chromosome (Ph) and a normal karyotype were reported as the second and third most common karyotypes, respectively. We investigated cytogenetic karyotypes of six t-B-ALL cases with a pre-B cell immunophenotype. Ph + t-B-ALL was noted in four of six patients previously treated with radiation and/or chemotherapy. In addition, one case demonstrated MLL rearrangement at 11q23 locus while one case demonstrated normal cytogenetic karyotype. Five of the six t-B-ALL patients had persistent leukemia following initiation of chemotherapy for secondary leukemia with survival ranging from 10 to 21 months. To our knowledge, only fourteen patients with Ph + t-B-ALL have been described in the literature. In the current study, three of four cases with Ph + t-B-ALL were associated with treated breast carcinoma while one patient was treated for Hodgkin lymphoma. All four patients had undergone radiation therapy. The results may indicate a plausible association between Ph+t-B-ALL and prior radiation exposure.

The genetics of the myelodysplastic syndromes: Classical cytogenetics and recent molecular insights

Myelodysplastic syndromes (MDS) are a complex group of clonal hematopoietic disorders with an attendant diverse array of associated genetic changes. Conventional cytogenetics plays a prominent and well-established role in determining the contemporary diagnosis and prognosis of these disorders. More recently, molecular approaches have been useful in further characterizing this group of diseases, albeit in a largely experimental context, with the detection of changes at the single gene level including mutations, amplification and epigenetic phenomena. Nevertheless, we remain largely ignorant of the genetic underpinnings of MDS. Here we briefly review the established role of cytogenetics in MDS, and emphasize recent advances in unraveling the genetics of MDS, with a view towards how such findings might facilitate our ability to understand, diagnose and treat these disorders in a more rational manner.

Therapy-related Ph+ leukemia after both bone marrow and mesenchymal stem cell transplantation for hypophosphatasia

Bone marrow (BM) transplantation (BMT) is one of the treatment strategies for congenital metabolic disease, but leukemia secondary to intensive cytoreductive treatment is a major concern. Besides BM cells, mesenchymal stem cells (MSC) are also used for transplantation. An 8-month-old girl with hypophosphatasia underwent transplantation of haploidentical BM cells followed by two transplants of MSC obtained from her father to facilitate osteogenesis. Fludarabine(Flu)/cyclophosphamide (CPA)/anti-thymocyte globulin were used for myeloablative conditioning, but the patient developed therapy-related leukemia harboring t(9;22)(q34;q11.2); minor BCR-ABL (t-leukemia with Ph) at the age of 32 months. At the age of 40 months she underwent a second BM and third MSC transplant from the same donor. Thereafter, she achieved complete histological and molecular remission. The present case suggests that the combination of cytotoxic agents (Flu/CPA) and MSC led to t-leukemia with Ph as a consequence of chromosome instability and suppression of host anti-tumor immunity.

Longitudinal bone marrow evaluations for myelodysplasia in patients with myeloma before and after treatment with lenalidomide

Lenalidomide (LEN) treatment in multiple myeloma (MM) results in a superior outcome. However, there is concern for increased myelodysplastic syndrome/acute myeloid leukemia (MDS/AML) associated with LEN. Thus, bone marrow morphology and cytogenetics studies from 40 patients were evaluated for early signs of MDS prior to therapy, during therapy and at follow-up. Newly diagnosed patients with MM treated with LEN and dexamethasone (LD) alone or followed by autologous stem cell transplant (LD/ASCT), or patients with relapsed/refractory MM treated with LEN, bendamustine and dexamethasone (BLD) were included. One patient developed MDS. Baseline prevalence of mild morphologic myelodysplasia was highest in pretreated patients with MM (BLD, 71%), but was also seen in newly diagnosed patients (LD and LD/ASCT, 17%). The prevalence of myelodysplasia did not increase over time. Thus, this study did not reveal rapidly emerging MDS in 39 of 40 patients with MM treated with LEN. The development of MDS in one patient suggests that longer follow-up is needed for all.

Engineering mouse models with myelodysplastic syndrome human candidate genes; how relevant are they?

Myelodysplastic syndromes represent particularly challenging hematologic malignancies that arise from a large spectrum of genetic events resulting in a disease characterized by a range of different presentations and outcomes. Despite efforts to classify and identify the key genetic events, little improvement has been made in therapies that will increase patient survival. Animal models represent powerful tools to model and study human diseases and are useful pre-clinical platforms. In addition to enforced expression of candidate oncogenes, gene inactivation has allowed the consequences of the genetic effects of human myelodysplastic syndrome to be studied in mice. This review aims to examine the animal models expressing myelodysplastic syndrome-associated genes that are currently available and to highlight the most appropriate model to phenocopy myelodysplastic syndrome disease and its risk of transformation to acute myelogenous leukemia.

Therapy-related acute leukemia with mixed phenotype and t(9;22)(q32;q11.2): a case report and review of the literature

Therapy-related acute leukemia showing mixed phenotype is extremely rare. We report a 49-year-old woman who presented with palpable masses in her neck and back. She had received systemic chemotherapy (adriamycin and cisplatin) and radiotherapy for endometrial adenocarcinoma 7 years before. Her peripheral blood and bone marrow showed increased blasts, which coexpressed myeloid (CD13, CD33, and myeloperoxidase) and B-lymphoid antigens (CD19 and CD79a). Cytogenetic analysis showed a karyotype of 46,XX,dup(1)(q21q32),add(5)(q33),t(9;22)(q34;q11.2)[12]/47,idem,+der(22)t(9;22)[8], and BCR/ABL1 rearrangement was detected. Leukemic infiltration was also confirmed in her back mass. After induction chemotherapy with idarubicin, cytarabine, and imatinib, she achieved complete remission. Only 2 cases of therapy-related acute leukemia with mixed phenotype have been reported so far: one with hyperploidy and the other with t(1;21)(p36;q22). To the best of our knowledge, this is the first case of therapy-related acute leukemia with mixed phenotype and t(9;22) as well as extramedullary leukemic infiltrations.

Myelodysplastic syndrome with inv(3)(q21q26.2) or t(3;3)(q21;q26.2) has a high risk for progression to acute myeloid leukemia

Acute myeloid leukemia (AML) with inv(3) (q21q26.2) or t(3;3)(q21;q26.2) is a distinct subtype in the World Health Organization classification. The natural history of myelodysplastic syndrome (MDS) associated with these cytogenetic aberrations is poorly understood. We studied 17 MDS (11 de novo and 6 therapy related) and 3 chronic myelomonocytic leukemia (CMML) cases associated with inv(3) (q21q26.2) or t(3;3)(q21;q26.2). The de novo cases were further classified as refractory cytopenia with multilineage dysplasia (n = 8) and refractory anemia with excess blasts (n = 3). Isolated inv(3)/t(3;3) was identified in 4 cases, whereas -7/7q (n = 13) and -5/5q (n = 6) were common additional aberrations. Nineteen patients died, including 13 in whom the disease progressed to AML after a median of 7 months. Median survival for patients with de novo disease was similar to that for patients with therapy-related MDS (13 vs 17.5 months). MDS or CMML with inv(3)/t(3;3) are aggressive diseases with a high risk of progression to AML.

Therapy-related leukemia following chemoradiotherapy for esophageal cancer

Chemoradiotherapy has improved the outcome of patients with esophageal cancer. Although a sufficiently long-time survival has resulted in the increase of several treatment-related late toxicities, little is still known about the incidence of secondary malignancies. In our hospital, 348 patients with esophageal cancer received chemotherapy consisting of nedaplatin and 5-fluorouracil and concurrent irradiation. Median and average follow-up durations were 8 and 21 months (1-92), respectively. Four patients developed leukemia after 19-48 months of follow-up. Two patients were diagnosed with overt leukemia from myelodysplastic syndrome presenting a complex karyotype, including the deletion of chromosome 5 or 7. Notably, one patient showed an additional chromosomal abnormality with t(9;22)(q34;q11). Other patients developed acute myeloid leukemia with t(9;22)(q34;q11) and Burkitt leukemia with t(8;14)(q24;q32). All patients eventually succumbed to leukemia. Platinum and fluorouracil have shown relatively lower risks for secondary malignancies in comparison with alkylating agents and topoisomerase II inhibitors. Especially, nedaplatin has never been described to introduce secondary neoplasms. Our report supports the idea that the concurrent administration of radiotherapy with these agents affects the risk of leukemia. Interestingly, rare balanced chromosomal abnormalities were observed in the present cases, thus providing new insights into the leukemogenesis of therapy-related leukemia.

Therapy-related myeloid neoplasms

Session 5 of 2007 Workshop of the Society for Hematopathology/European Association for Haematopathology focused on therapy-related myeloid neoplasms. This report discusses the diversity and relevance of clinical, pathologic, and genetic features and provides an update on the pathogenesis of these disorders. We highlight common diagnostic issues such as the differentiation between therapy-related myelodysplastic syndrome and therapy-related acute erythroid leukemia. As similar therapeutic interventions are frequently considered for patients with either of these diagnoses, in the current World Health Organization classification, regardless of morphologic presentation, therapy-related myeloid neoplasms are considered together as a unique clinicopathologic syndrome of therapy-related myelodysplastic syndrome/acute myeloid leukemia. Nevertheless, recognition of the diverse morphologic features is crucial as bone marrow morphologic examination remains the first and important step of patient evaluation. We also present examples of therapy-related acute myeloid leukemias with recurrent cytogenetic abnormalities. In these cases, the precise classification is clinically important because it is associated with distinct clinical outcome.

NUP98-NSD3 fusion gene in radiation-associated myelodysplastic syndrome with t(8;11)(p11;p15) and expression pattern of NSD family genes

Chromosomal 11p15 abnormality of therapy-related myelodysplastic syndrome (t-MDS)-acute myeloid leukemia (AML) is rare. NUP98-NSD3 fusion transcripts have been detected previously in one patient with AML and one patient with t-MDS having t(8;11)(p11;p15). Here we present the case of a 60-year-old man with radiation-associated MDS (r-MDS) carrying chromosome abnormalities, including t(8;11)(p11;p15) and del(1)(p22p32). Fluorescence in situ hybridization analysis demonstrated that the NUP98 gene at 11p15 was split by the translocation. Southern blot analysis of bone marrow cells showed both rearrangements of NUP98 and NSD3 genes. Reverse transcriptase-polymerase chain reaction (RT-PCR) followed by sequence analysis revealed the presence of both NUP98-NSD3 and NSD3-NUP98 fusion transcripts. Expression analysis by RT-PCR showed that NSD3 as well as NSD1 and NSD2 was ubiquitously expressed in leukemic cell lines and Epstein-Barr virus transformed B lymphocyte cell lines derived from the normal adult lymphocytes examined. Two isoforms of NSD3, NSD3S and NSD3L (but not NSD3L2), were expressed in leukemic cell lines and were fused to NUP98 in our patient, suggesting that qualitative change of these two isoforms of NSD3 by fusion with NUP98 might be related to leukemogenesis, although the function of each isoform of the NSD3 gene remains unclear.

Coexistence of T-cell lymphoblastic lymphoma and myelodysplastic syndrome in a child

A 10-year-old girl presented with T-cell lymphoblastic lymphoma of the mediastinum coexisting with myelodysplastic syndrome. Bone marrow examination showed trilineage dysplasia with no evidence of lymphoma cells. Intensive chemotherapy led to a marked reduction in the mediastinal tumor, but no improvement in bone marrow findings. Unrelated cord blood transplantation was performed, resulting in completely chimeric bone marrow cells. A possible explanation for the simultaneous presentation of T-cell lymphoblastic lymphoma and myelodysplastic syndrome is that transformation occurs in pluripotent stem cells differentiating into myeloid and lymphoid cells.

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.

Additional cytogenetic changes and previous genotoxic exposure predict unfavorable prognosis in myelodysplastic syndromes and acute myeloid leukemia with der(1;7)(q10;p10)

We analyzed 23 patients with myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML) showing a der(1;7)(q10;p10) [hereafter der(1;7)] to identify the exact predictive factor of this cytogenetic change. Eight (34.8%) patients, including six with MDS and two with AML patients, had a previous history of genotoxic exposure, especially radiation and/or antimetabolites. Patients with der(1;7) consisted of three groups: one third of patients had a previous history of genotoxic agents, one third had additional cytogenetic changes at the time of MDS/AML diagnosis without previous exposure history, and the remaining one third had neither a previous exposure history nor additional cytogenetic changes. The current study demonstrated that the poor outcome of MDS/AML with der(1;7) is caused by the high frequency of associated risk factors (i.e., previous history of genotoxic exposure, the presence of additional cytogenetic changes, or both). Identification of prognostic disadvantage might be required for applying the appropriate strategy in managing MDS/AML patients with rare der(1;7) abnormality.

Simultaneous presentation of acute monoblastic leukemia and mantle cell lymphoma: case report and review of the literature

This paper reports a 73-year old woman with simultaneous presentation of acute monoblastic leukemia (acute myeloid leukemia (AML), French-American-British (FAB) type M5a) and mantle cell lymphoma. The patient presented with wasting, generalized lymphadenopathy, an extensive infiltrative rash and pancytopenia. Bone marrow and lymph node histopatholology showed extensive infiltration by leukemic monoblasts. Marrow cytogenetics revealed a complex karyotype, including t(8;16)(p11;p13). Flow cytometric immunophenotyping of peripheral blood, lymph node and bone marrow demonstrated two populations, expressing CD5, CD19, CD20 and CD22 and CD45, HLA-DR, CD13, CD33, CD14 and CD38, respectively. A focus of abnormal lymphocytes in the lymph node biopsy demonstrated BCL1 expression and t(11;14)(p11;p13) by fluorescence in situ hybridization and immunoglobulin heavy chain gene rearrangement by the polymerase chain reaction. The patient received infusional cytarabine, daunorubicin and etoposide chemotherapy, with complete remission of both the AML and the mantle cell leukemia. To the authors' knowledge, this is the first report of simultaneous presentations of AML, FAB M5a and mantle cell lymphoma. The case is discussed and the literature is reviewed.

Causes of oncogenic chromosomal translocation

Non-random chromosomal translocations are frequently associated with a variety of cancers, particularly hematologic malignancies and childhood sarcomas. In addition to their diagnostic utility, chromosomal translocations are increasingly being used in the clinic to guide therapeutic decisions. However, the mechanisms that cause these translocations remain poorly understood. Illegitimate V(D)J recombination, class switch recombination, homologous recombination, non-homologous end-joining and genome fragile sites all have potential roles in the production of non-random chromosomal translocations. In addition, mutations in DNA-repair pathways have been implicated in the production of chromosomal translocations in humans, mice and yeast. Although initially surprising, the identification of these same oncogenic chromosomal translocations in peripheral blood from healthy individuals strongly suggests that the translocation is not sufficient to induce malignant transformation, and that complementary mutations are required to produce a frank malignancy.

Hematologic aspects of myeloablative therapy and bone marrow transplantation

The transplantation of bone marrow cells or isolated hematopoietic stem cells from the bone marrow or peripheral blood is a widely utilized form of therapy for patients with incurable diseases of the hematopoietic and immune systems. Successful engraftment of the transplanted stem cells in an adequately prepared recipient normally leads to bone marrow reconstitution over a period of several weeks, accompanied by more gradual reconstitution of the immune system. Since the recipient is profoundly ill during the initial treatment period, laboratory data is critical for monitoring engraftment, detecting residual/recurrent disease, and identifying problems that may delay bone marrow reconstitution or lead to other medical complications. Accurate blood cell counts are imperative, and most bone marrow transplantation patients undergo periodic monitoring with bone marrow aspirates and biopsies with cytogenetic, molecular, and multiparametric flow cytometric studies. The potential complications of bone marrow transplantation include engraftment failure and delayed engraftment, infection, residual bone marrow disease, acute and chronic graft versus host disease, myelofibrosis, therapy-related acute leukemia, post-transplant lympho-proliferative disorders, and toxic myelopathy.

Genetic testing in the myelodysplastic syndromes: molecular insights into hematologic diversity

The myelodysplastic syndromes (MDS) are associated with a diverse set of acquired somatic genetic abnormalities. Bone marrow karyotyping provides important diagnostic and prognostic information and should be attempted in all patients who are suspected of having MDS. Fluorescent in situ hybridization (FISH) studies on blood or marrow may also be valuable in selected cases, such as patients who may have 5q- syndrome or those who have undergone hematopoletic stem cell transplantation. The MDS-associated cytogenetic abnormalities that have been defined by karyotyping and FISH studies have already contributed substantially to our current understanding of the biology of malignant myeloid disorders, but the pathobiological meaning of common, recurrent chromosomal lesions such as del(5q), del(20q), and monosomy 7 is still unknown. The great diversity of the cytogenetic findings described in MDS highlights the molecular heterogeneity of this cluster of diseases. We review the common and pathophysiologically interesting genetic abnormalities associated with MDS, focusing on the clinical utility of conventional cytogenetic assays and selected FISH studies. In addition, we discuss a series of well-defined MDS-associated point mutations and outline the potential for further insights from newer techniques such as global gene expression profiling and array-based comparative genomic hybridization.

Philadelphia chromosome-positive acute lymphoblastic leukemia secondary to chemoradiotherapy for Ewing sarcoma. Report of two cases and concise review of the literature

Survivors of childhood solid tumors including Ewing sarcoma (ES) have an increased risk of secondary malignant neoplasms (SMNs) as a consequence of exposure to chemotherapy and/or radiation (see: Bhatia S, Sklar C. Nat Rev Cancer 2002;2:124-132). The most common hematologic SMNs are myelodysplasia (MDS) and acute myelogenous leukemia (AML). Acute lymphoblastic leukemia (ALL) is uncommon in this patient population, and Philadelphia chromosome positive (Ph+) ALL in particular, is rare. We report herein two cases of young adult patients who were both diagnosed with Ph+ ALL 19 years after successful treatment for ES with combined modality therapy. A review of the relevant literature follows the case reports.

[Chromosomal abnormalities in secondary myelodysplastic syndromes and leukemias]

Secondary leukemias group essentially together myelodysplastic syndromes and acute leukemias, therapy-related (chemo- or radio-), or consecutive to environmental factors. It's now proven that some recurrent abnormalities are associated with effects of therapeutic agents, as -5/del(5q), -7/del(7q) linked to alkylating agents, or 11q23 and 21q22 abnormalities linked to inhibitors of Topoisomerase II. Even if important differences between secondary and "de novo" forms exist, the discrimination between these 2 categories is not always obvious: many common chromosomal abnormalities, "de novo" leukemias in older patients having characteristics close to those of postalkylating leukemias, neonatal forms possibly secondary to maternal affect. Recent studies identified some others chromosomal abnormalities in the secondary leukemias and confirmed the poor prognosis of these hemopathies. This review sums up criterions, circumstances and cytogenetic abnormalities.

High frequency of pro-B acute lymphoblastic leukemia in adults with secondary leukemia with 11q23 abnormalities

To evaluate the frequency and cytogenetic and immunophenotypic features of therapy-related, precursor B-cell acute lymphoblastic leukemia (ALL), 152 cases of immature B-cell ALL were reviewed. These were compared to the frequency of therapy-related acute myeloid leukemia (t-AML) during the same time period. Eight ALL cases with a prior diagnosis of malignancy were identified, including six (4.0%) with prior therapy considered to be therapy-related ALL (t-ALL). The t-ALL cases followed treatment for breast carcinoma (two cases), lung carcinoma (two cases), lymphocyte predominance Hodgkin's disease and follicular lymphoma with a latency period of 13 months to 8 years. All t-ALL cases had a pro-B (CD10-negative) immunophenotype with significantly higher expression of CD15 and CD65, compared to the de novo CD10-positive ALL cases. All six t-ALL cases had MLL abnormalities by fluorescence in situ hybridization, and four showed t(4;11)(q21;q23). These represented half of all 11q23-positive adult ALL cases. During the same time period, 4.9% of all AML cases were considered t-AML. There was a 16.7% frequency of 11q23 abnormalities in the t-AML group. Despite the similar frequency in therapy-related disease among ALL and AML cases, there were differences in the frequency of the diseases and t-ALL represented 12% of all therapy-related leukemias. However, t-ALL represented 46% of all 11q23-positive therapy-related leukemias. The immunogenetic features of t-ALL appear distinct and may aid in identifying more cases of this disease type in the future.

Rearrangement of the MOZ gene in pediatric therapy-related myelodysplastic syndrome with a novel chromosomal translocation t(2;8)(p23;p11)

In this study, we examined a pediatric case of therapy-related myelodysplastic syndrome (tMDS). The symptoms developed 17 months after treatment for acute myeloblastic leukemia (AML, M2 subtype according to the French-American-British [FAB] classification) involving a chromosome abnormality at t(8;21)(q22;q22). Upon diagnosis of tMDS, spectral karyotyping analysis detected a new chromosomal translocation at t(2;8)(p23;p11.2). In addition, fluorescence in situ hybridization analysis suggested a rearrangement in the monocytic leukemia zinc finger (MOZ) gene, located in the 8p11 region of chromosome 8. However, no partner gene on 2p23 could be identified. To our knowledge, this is the first report of tMDS associated with a rearrangement of the MOZ gene. MOZ-linked fusion proteins such as MOZ-CBP (CREB binding protein), MOZ-TIF2 (transcriptional intermediary factor 2), and MOZ-p300 (adenoviral E1A-associated protein) are associated with AML chromosomal abnormalities at t(8;16)(p11;p13), inv(8)(p11q13), and t(8;22)(p11;q13), respectively, and are thought to account for leukemogenesis occurring through the aberrant regulation of histone acetylation. Through a similar mechanism, we believe that MOZ, fused to an unidentified partner gene at 2p23, may have caused an alteration in histone acetylation, resulting in the development of tMDS in this patient.

Clonal cytogenetic abnormalities in bone marrow specimens without clear morphologic evidence of dysplasia: a form fruste of myelodysplasia?

Cytogenetic abnormalities suggestive of a myeloid disorder are occasionally observed in the bone marrow (BM) cells of patients with morphologically and immunohistochemically unremarkable marrow aspirates and biopsies. Between 1994 and 2000, 55 such patients were seen at our institution (34 men; median age of 66 years). The indications for BM sampling included unexplained cytopenias (31 patients), staging or follow-up of a lymphoproliferative disorder or a plasma cell dyscrasia (18 patients), or another miscellaneous reason (6 patients). Specific cytogenetic abnormalities included a 20q deletion or monosomy 20 (10 patients), a chromosome 7 deletion (8 patients), +8 (5 patients), del(5q) or a 5q translocation (4 patients), and del(13q) (2 patients). Eleven patients had a complex karyotype. As of January 2002, 23 of the 55 patients were dead; median follow-up for living patients is 20 months. Of the 23 dead patients, 1 died of acute myelogenous leukemia (AML) and 6 of complications related to cytopenias. This study provides support for obtaining cytogenetic studies in patients with unexplained cytopenias if a morphologic explanation for the cytopenias is lacking. Continued follow-up of this heterogeneous cohort and further studies of similar patients will more clearly define the disease processes and prognosis for this constellation of laboratory findings.

The myelodysplastic syndrome(s): a perspective and review highlighting current controversies

The myelodysplastic syndrome (MDS) includes a diverse group of clonal and potentially malignant bone marrow disorders characterized by ineffective and inadequate hematopoiesis. The presumed source of MDS is a genetically injured early marrow progenitor cell or pluripotential hematopoietic stem cell. The blood dyscrasias that fall under the broad diagnostic rubric of MDS appear to be quite heterogeneous, which has made it very difficult to construct a coherent, universally applicable MDS classification scheme. A recent re-classification proposal sponsored by the World Health Organization (WHO) has engendered considerable controversy. Although the precise incidence of MDS is uncertain, it has become clear that MDS is at least as common as acute myelogenous leukemia (AML). There is considerable overlap between these two conditions, and the former often segues into the latter; indeed, the distinction between AML and MDS can be murky, and some have argued that the current definitions are arbitrary. Despite the discovery of several tantalizing pathophysiological clues, the basic biology of MDS is incompletely understood. Treatment at present is generally frustrating and ineffective, and except for the small subset of patients who exhibit mild marrow dysfunction and low-risk cytogenetic lesions, the overall prognosis remains rather grim. In this narrative review, we highlight recent developments and controversies within the context of current knowledge about this mysterious and fascinating cluster of bone marrow failure states.

A novel fusion variant of the MORF and CBP genes detected in therapy-related myelodysplastic syndrome with t(10;16)(q22;p13)

We report a case of therapy-related myelodysplastic syndrome (t-MDS) with t(10;16)(q22;p13), in which novel fusion transcripts of the MORF and CBP genes were detected. In one MORF-CBP fusion transcript, exon 15 of the MORF gene was fused in frame with exon 5 of the CBP gene. In a reciprocal CBP-MORF transcript, exon 4 of the CBP gene was fused in frame with exon 16 of the MORF gene. This is the first reported case of t-MDS associated with t(10;16), and provides molecular evidence that the novel MORF-CBP and/or CBP-MORF fusion protein(s) might play an important role in the development of t-MDS.