Atypical chronic myelomonocytic leukemia with eosinophilia and translocation (5;12). A new association

A Novel IL3-ETV6 Fusion in Chronic Eosinophilic Leukemia Not Otherwise Specified With t(5; 12) (q31; p13): A Case Report and Literature Review

Chronic eosinophilic leukemia not otherwise specified (CEL-NOS) is classified as Myeloproliterative Neoplasms (MPN) and refers to chronic eosinophilic leukemia with some atypical recurrent genetic evidence(1). A rare fusion of ACSL6-ETV6 was previously identified in patients with the t(5;12) (q31; p13) karyotype(2). Here, we report a case of CEL-NOS with a translocation of t(5;12) (q31; p13) and identify IL3-ETV6 transcription, which has not been identified in hematologic diseases. In this patient, eosinophilia was observed. And compared with CEL-NOS patients without ETV6 fusion, a higher mRNA expression level of IL3 was found. After failing treatment with dasatinib, the patient was given hydroxyurea (HU). Subsequently his white blood cell (WBC) and eosinophils decreased significantly and remained in the normal range until publication. Due to the side effects, treatment with HU was replaced by PEG-interferon (PEG-IFN). What’s more, we summarized the case in our study and 21 patients with the karyotype of t(5; 12) (q31; p13) reported by other groups. It was found that most of them had similar clinical manifestations of eosinophilia and tyrosine kinase inhibitor (TKI) insensitivity. The ectopic mRNA expression of IL3 may be the main cause of eosinophilia, and HU and prednisone acetate (PAT), as well as IFN, were considered treatments for this group.

Chronic myelomonocytic leukemia: Forefront of the field in 2015

Chronic myelomonocytic leukemia (CMML) includes components of both myelodysplastic syndrome and myeloproliferative neoplasms and is associated with a characteristic peripheral monocytosis. CMML is caused by the proliferation of an abnormal hematopoietic stem cell clone and may be influenced by microenvironmental changes. The disease is rare and has undergone revisions in its classification. We review the recent classification strategies as well as diagnostic criteria, focusing on CMML's genetic alterations and unique pathophysiology. We also discuss the latest molecular characterization of the disease, including how molecular factors affect current prognostic models. Finally, we focus on available treatment strategies, with a special emphasis on experimental and forthcoming therapies.

The Differential Diagnosis of Eosinophilia in Neoplastic Hematopathology

Eosinophilia in the peripheral blood is classified as primary (clonal) hematologic neoplasms or secondary (nonclonal) disorders, associated with hematologic or nonhematologic disorders. This review focuses on the categories of hematolymphoid neoplasms recognized by the 2008 World Health Organization Classification of Tumours and Haematopoietic and Lymphoid Tissues that are characteristically associated with eosinophilia. We provide a systematic approach to the diagnosis of these neoplastic proliferations via morphologic, immunophenotypic, and molecular-based methodologies, and provide the clinical settings in which these hematolymphoid neoplasms occur. We discuss recommendations that eosinophilia working groups have published addressing some of the limitations of the current classification scheme.

Mixed-lineage eosinophil/basophil crisis in MDS: a rare form of progression

BACKGROUND

Basophilic crisis and eosinophilia are well recognized features of advanced chronic myeloid leukaemia. In other myeloid neoplasms, however, transformation with marked basophilia and eosinophilia is considered unusual.

DESIGN

We examined the long-term follow-up of 322 patients with de novo myelodysplastic syndromes (MDS) to define the frequency of basophilic, eosinophilic and mixed lineage (basophilic and eosinophilic) transformation.

RESULTS

Of all patients, only one developed mixed lineage crisis (>or= 20% basophils and >or= 20% eosinophils). In this patient, who initially suffered from chronic myelomonocytic leukaemia, basophils increased to 48% and eosinophils up to 31% at the time of progression. Mixed lineage crisis was not accompanied by an increase in blast cells or organomegaly. The presence of BCR/ABL and other relevant fusion gene products (FIP1L1/PDGFRA, AML1/ETO, PML/RAR alpha, CBF beta/MYH11) were excluded by PCR. Myelomastocytic transformation/myelomastocytic leukaemia and primary mast cell disease were excluded by histology, KIT mutation analysis, electron microscopy and immunophenotyping. Basophils were thus found to be CD123+, CD203c+, BB1+, KIT- cells, and to express a functional IgE-receptor. Among the other patients with MDS examined, 4(1.2%) were found to have marked basophilia (>or= 20%) and 7(2.1%) were found to have massive eosinophilia ( >or= 20%), whereas mixed-lineage crisis was detected in none of them.

CONCLUSIONS

Mixed basophil/eosinophil crisis may develop in patients with MDS but is an extremely rare event.

Current Treatment Options: Impact of Cytogenetics on the Course of Myelodysplasia

The heterogeneity of myelodysplastic syndromes (MDS) has driven the search for unifying biologic and clinical features that would stratify patients into distinct prognostic and therapeutic subgroups. Cytogenetics has been shown to impact the course of myelodysplasia. Despite the presence of non-random cytogenetic abnormalities in approximately 50% of MDS patients, it is significant that only a proportion of metaphases may contain the abnormality. Clonality studies however show that the karyotypically normal metaphases are still part of the MDS clone. This would suggest that the chromosomal abnormality may not be the initiating lesion in MDS, and that the gross karyotypic changes represent clonal evolution in a genetically unstable population. Yet, as will be described below, specific cytogenetic abnormalities are associated with clinically and biologically distinct forms of the disease, most notable in the response of del(5q) patients to lenalidomide. One possible explanation for the appearance of non-random mutational events could relate to the interaction of MDS cells with their microenvironment. Whatever the initiating lesion in the MDS stem cell, the end result is a clonal expansion where the marrow becomes populated by the monoclonal progeny of this cell. Interaction of these cells with a microenvironment which has been shown to be rich in pro-apoptotic cytokines such as tumor necrosis factor alpha (TNFa), leads to increased genetic instability. Hypoxia mediated decrease in DNA repair enzymes could further accelerate mutational events culminating in accumulation of multiple chromosomal abnormalities. Some of these chromosomal changes are associated with increased sensitivity to specific drugs. Lenalidomide has shown a high degree of efficacy in MDS patients with del(5q), although the target for the drug is unknown since a small but significant subset of MDS patients without del(5q) abnormality also respond to the drug. In contrast, the molecular target for imatinib mesylate is known; mutations in tyrosine kinase receptor family of genes found in patients with t(5;12) and del(4q12) make these individuals sensitive to the drug. Patients with isolated trisomy 8 have an immune component to the disease phenotype which can be targeted by cyclosporine and or anti-thymocyte globulin (ATG), especially in the presence of a PNH (paroxysmal nocturnal hemoglobinurea) clone. In the absence of these specific cytogenetic abnormalities described above, the two FDA approved hypomethylating agents 5 azacytidine and decitabine should be considered as therapeutic alternatives.

Genetics of Myeloid Malignancies: Pathogenetic and Clinical Implications

Myeloid malignancies are clonal disorders that are characterized by acquired somatic mutation in hematopoietic progenitors. Recent advances in our understanding of the genetic basis of myeloid malignancies have provided important insights into the pathogenesis of acute myeloid leukemia (AML) and myeloproliferative diseases (MPD) and have led to the development of novel therapeutic approaches. In this review, we describe our current state of understanding of the genetic basis of AML and MPD, with a specific focus on pathogenetic and therapeutic significance. Specific examples discussed include RAS mutations, KIT mutations, FLT3 mutations, and core binding factor rearrangements in AML, and JAK2 mutations in polycythemia vera, essential thrombocytosis, and chronic idiopathic myelofibrosis.

Cytogenetics of chronic myeloproliferative disorders and related myelodysplastic syndromes

The only MPD associated with any specific chromosome anomaly is CML, which is linked with t(9;22)(q34;q11.2) or a variant of this anomaly. An association exists for del(13)(q12q14) and CIMF; t(5;12)(q33;p13) and CEL; and del(20q11), +8, and +9 and PV, but these anomalies can be seen in various hematologic malignancies. The most common chromosomal anomalies among MPD in order of frequency are t(9;22)(q34;q11.2), -Y, +8, +9, -7, del(20) (q11q13), del(13)(q12q14), del(5)(q13q33), and del(12)(p12). FISH techniques are useful for MPD to study inadequate bone marrow or blood specimens and to monitor disease status among patients with known chromosome anomalies, but they are not more sensitive than conventional chromosome studies.

Pathology of the myeloproliferative diseases

The classification of myeloid neoplasms now includes CMPD, mixed CMPD/ MDS, MDS, and acute myeloid leukemias. CMPD and CMPD/MDS, both clonal stem cell diseases, share myeloproliferative features, including typical hypercellular marrows, organomegaly, and cell lineage maturation. The CMPD generally differ by which myeloid cell lineage dominates hematopoiesis, and the main diseases include CML, PV, ET, and CIM. The mixed CMPD/MDS disorders also show dysplastic features and variable amounts of effective hematopoiesis; these disorders include CMML, JMML, and atypical CML. Given the overlap in morphology among these diseases, correlation with clinical, hematologic, and cytogenetic/molecular genetic findings is imperative for precise classification.

Chromosomal rearrangement in Down syndrome with acute myeloid leukemia

The incidence of acute leukemia in children with Down syndrome (DS) is high as compared to general population. Recent findings have demonstrated that DS children with acute myeloid leukemia (AML) have the highest event free survival rates with high dose cytosine arabinoside (Ara-C). We present 3 year-old DS female child with AML-M5, whose chromosomal analysis revealed constitutional t(21;21) alongwith del(5)(q31q33) and a unique translocation t(16;20)(q13;q12). After chemotherapy, child achieved complete clinical remission. Karyotype analysis of remission marrow showed disappearance of abnormal clone of der(20) t(16;20)(q13;q12), del(5q) indicating cytogenetic remission too. This case alongwith supportive literature indicate that pediatric DS-AML is a distinct biologic sub-group differs from that of non-DS-AML with respect to chemosensitivity.

Chronic myelomonocytic leukemia with abnormal bone marrow eosinophils

Chronic myelomonocytic leukemia with eosinophilia is a recently defined rare entity frequently associated with t(5;12)(q33;p13) translocation. It usually shows a peripheral eosinophil count greater than 1500/microL. However, the literature contains a small subset of cases in which the major manifestation is bone marrow eosinophilia. We report a case similar to that subset and discuss our finding that the immature eosinophils are identical to those seen in acute myelomonocytic leukemia with abnormal bone marrow eosinophils.

Cytogenetic and molecular genetic aspects of childhood myeloproliferative/myelodysplastic disorders

Of the myeloproliferative/myelodysplastic disorders (MPD/MDS) that occur in childhood most, regarding the cytogenetic and molecular genetic basis, is known about the two purely paediatric disorders: juvenile myelomonocytic leukaemia (JMML) and transient myeloproliferative disorder (TMD). Although much has been published about these two disorders, their aetiology is by no means fully established. It would appear, however, that in this paediatric subset of MPDs a stage/developmentally specific vulnerability for proliferation and transformation exists. The study of the molecular basis of many other MPD-like syndromes that also occur in childhood, has been greatly accelerated by the identification of rare, but recurring, cytogenetic abnormalities involving 8p11 and 5q31-33. Good collaborative studies could result in similar progress being made in the understanding of JMML and TMD.

Two balanced and novel chromosomal translocations in myeloid malignancies. characterization by multiplex fluorescence in situ hybridization

We describe two novel chromosomal translocations in two cases of leukemia in which these translocations were further characterized as the sole acquired karyotypic abnormality by mutliplex fluorescence in situ hybridization (M-FISH). They comprised a case of acute myeloid leukemia with t(6;10)(q21;p12) and a case of chronic myelomonocytic leukemia with t(5;12)(q34;q24). To the best of our knowledge, these two balanced translocations are novel and are hitherto unrecognized in hematologic malignancies. While the clinical and pathogenic significance of these translocations remains to be defined, the present report illustrates that M-FISH technology contributes to the exclusion of subtle or cryptic translocations in sole karyotypic aberrations and the confirmation of novel chromosomal arrangements in neoplastic disorders.

Chronic myelocytic leukemia with eosinophilia, t(9;12)(q34;p13), and ETV6-ABL gene rearrangement: case report and review of the literature

Chronic myelocytic leukemia (CML) is a chronic myeloproliferative disorder characterized by cytogenetic or molecular evidence of Philadelphia (Ph) chromosome, t(9;22)(q34;q11). Mild to moderate eosinophilia is commonly seen in CML. However, eosinophilia as a dominant feature of CML is extremely rare. We describe a case of Ph(-) CML with eosinophilia. Loeffler endocarditis, and t(9;12)(q34;p13) that resulted in an ETV6-ABL gene rearrangement/fusion identified to the best of our knowledge, for the first time by using commercially available fluorescence in situ hybridization probes.

Expression of CD4 on peripheral blood granulocytes. a novel finding in a case of myelodysplastic syndrome in association with t(5;12)

Myelodysplastic syndromes (MDS) are associated with cell maturation defects that can manifest as abnormal surface antigen expression. We describe a patient with refractory anemia with excess blasts, who presented with infection and extensive dysplastic features in peripheral blood granulocytes. The granulocytes expressed CD11b, CD13, CD15, CD33, and CD43. The granulocytes also expressed CD4 antigen. Cytogenetic analysis showed a clonal t(5;12)(q33;p13). The patient improved on antibiotics with partial improvement in the dysplastic features. However, shortly after, the patient experienced paravertebral extramedullary blast transformation followed by a leukemia phase of acute monoblastic leukemia. The patient died a few days later. This is the first report describing anomalous expression of CD4 on granulocytes in MDS. Since the breakpoint on chromosome 12 is near the CD4 gene, which is mapped to 12p12, we hypothesize that dysregulation of the CD4 gene may have occurred resulting in its persistent expression on mature and maturing granulocytes.

Myeloproliferative disorders with translocations of chromosome 5q31-35: role of the platelet-derived growth factor receptor Beta

Acquired reciprocal chromosomal translocations that involve chromosome bands 5q31-33 are associated with a significant minority of patients with BCR-ABL-negative chronic myeloid leukemias. The most common abnormality is the t(5;12)(q33;p13), which fuses the ETV6/TEL gene to the platelet-derived growth factor receptor-beta (PDGFRB), a receptor tyrosine kinase that maps to 5q33. PDGFRB is disrupted by other translocations and to date four additional partner genes (H4, HIP1, CEV14 and Rab5) have been reported. Clinically, most patients present with a myeloproliferative disorder (MPD) with eosinophilia, eosinophilic leukemia or chronic myelomonocytic leukemia and thus fall into the broader category of myeloproliferative disorders/myelodysplastic syndromes (MPD/MDS). With the advent of targeted signal transduction therapy, patients with rearrangement of PDGFRB might be better classified as a distinct subgroup of MPD/MDS.

TEL/PDGFβR Induces Hematologic Malignancies in Mice That Respond to a Specific Tyrosine Kinase Inhibitor

The TEL/PDGFβR fusion protein is expressed as the consequence of a recurring t(5;12) translocation associated with chronic myelomonocytic leukemia (CMML). Unlike other activated protein tyrosine kinases associated with hematopoietic malignancies, TEL/PDGFβR is invariably associated with a myeloid leukemia phenotype in humans. To test the transforming properties of TEL/PDGFβR in vivo, and to analyze the basis for myeloid lineage specificity in humans, we constructed transgenic mice with TEL/PDGFβR expression driven by a lymphoid-specific immunoglobulin enhancer-promoter cassette. These mice developed lymphoblastic lymphomas of both T and B lineage, demonstrating that TEL/PDGFβR is a transforming protein in vivo, and that the transforming ability of this fusion is not inherently restricted to the myeloid lineage. Treatment of TEL/PDGFβR transgenic animals with a protein tyrosine kinase inhibitor with in vitro activity against PDGFβR (CGP57148) resulted in suppression of disease and a prolongation of survival. A therapeutic benefit was apparent both in animals treated before the development of overt clonal disease and in animals transplanted with clonal tumor cells. These results suggest that small-molecule tyrosine kinase inhibitors may be effective treatment for activated tyrosine kinase–mediated malignancies both early in the course of disease and after the development of additional transforming mutations.

TEL/PDGFβR Induces Hematologic Malignancies in Mice That Respond to a Specific Tyrosine Kinase Inhibitor

The TEL/PDGFβR fusion protein is expressed as the consequence of a recurring t(5;12) translocation associated with chronic myelomonocytic leukemia (CMML). Unlike other activated protein tyrosine kinases associated with hematopoietic malignancies, TEL/PDGFβR is invariably associated with a myeloid leukemia phenotype in humans. To test the transforming properties of TEL/PDGFβR in vivo, and to analyze the basis for myeloid lineage specificity in humans, we constructed transgenic mice with TEL/PDGFβR expression driven by a lymphoid-specific immunoglobulin enhancer-promoter cassette. These mice developed lymphoblastic lymphomas of both T and B lineage, demonstrating that TEL/PDGFβR is a transforming protein in vivo, and that the transforming ability of this fusion is not inherently restricted to the myeloid lineage. Treatment of TEL/PDGFβR transgenic animals with a protein tyrosine kinase inhibitor with in vitro activity against PDGFβR (CGP57148) resulted in suppression of disease and a prolongation of survival. A therapeutic benefit was apparent both in animals treated before the development of overt clonal disease and in animals transplanted with clonal tumor cells. These results suggest that small-molecule tyrosine kinase inhibitors may be effective treatment for activated tyrosine kinase–mediated malignancies both early in the course of disease and after the development of additional transforming mutations.

Late appearance of t(5;12)(q31;p12) in acute myeloid leukemia associated with eosinophilia

We report here a case of acute myeloid leukemia with eosinophilia and t(5;12)(q31;p12) at the second relapse. This cytogenetic anomaly is thus associated with one step toward leukemia and eosinophilia.

Familial eosinophilia maps to the cytokine gene cluster on human chromosomal region 5q31-q33

Familial eosinophilia (FE) is an autosomal dominant disorder characterized by peripheral hypereosinophilia of unidentifiable cause with or without other organ involvement. To localize the gene for FE, we performed a genomewide search in a large U.S. kindred, using 312 different polymorphic markers. Seventeen affected subjects, 28 unaffected bloodline relatives, and 8 spouses were genotyped. The initial linkage results from the genome scan provided evidence for linkage on chromosome 5q31-q33. Additional genotyping of genetic markers located in this specific region demonstrated significant evidence that the FE locus is situated between the chromosome 5q markers D5S642 and D5S816 (multipoint LOD score of 6.49). Notably, this region contains the cytokine gene cluster, which includes three genes-namely, those for interleukin (IL)-3, IL-5, and granulocyte/macrophage colony-stimulating factor (GM-CSF)-whose products play important roles in the development and proliferation of eosinophils. These three cytokine genes were screened for potential disease-specific mutations by resequencing of a subgroup of individuals from the present kindred. No functional sequence polymorphisms were found within the promoter, the exons, or the introns of any of these genes or within the IL-3/GM-CSF enhancer, suggesting that the primary defect in FE is not caused by a mutation in any one of these genes but, rather, is caused by another gene in the area.

TEL gene rearrangements in myeloid malignancy

The TEL gene is a recently described, "promiscuous" gene with a role in both myeloid and lymphoid malignancy. It is unusual since there may be more than one mechanism by which its rearrangement through chromosomal translocation is leukemogenic. This article discusses the four potential mechanisms of TEL-mediated transformation. It is conceivable that the TEL gene is the common target for various translocations precisely because of this pleiotropy of pathogenic mechanisms by which TEL gene rearrangements can lead to cell transformation.

Pericentric inversion of chromosome 16 and eosinophilia in chronic myelomonocytic leukemia

We report a case of myelodysplastic syndrome with bone marrow eosinophilia and the chromosomal abnormality, inv(16)(p13q22). Hematologic findings including monocytosis and trilineage myelodysplasia were consistent with chronic myelomonocytic leukemia, and numerous abnormal eosinophils were present in the bone marrow. Chromosomal analysis of all metaphase cells from peripheral blood and bone marrow revealed in(16)(p13q22), which is well known characteristic of acute myelomonocytic leukemia with eosinophilia (M4Eo). Both monocytes and eosinophils in this case may be derived from common leukemic progenitors affected by inv(16)(p13q22).

Clinical aspects, cytogenetics and disease evolution in myelodysplastic syndromes

Myelodysplastic syndrome (MDS) is a morphologically characterized hematologic entity that is one of the clonal myeloproliferative disorders. Approximately 50 approximately 70% of MDS patients have cytogenetic abnormalities; these are usually chromosomal deletions, but some involve translocations such as t(1;7) (q10;p10). Translocations involving chromosomal regions 3q26 or 22q11 are often therapy-related. Recent studies have demonstrated that cytogenetic changes in MDS patients have clinical relevance. Accordingly, there are now scoring systems for predicting the prognoses of MDS patients. In this review, we describe the clinical significance of cytogenetic changes in MDS. We include MDS with some atypical forms, such as MDS with hypocellular bone marrow, MDS with minimal dysplasia, and MDS with myelofibrosis.

Diagnostic and prognostic significance of cytogenetics in adult primary myelodysplastic syndromes

Cytogenetic analysis has proven to be a mandatory part of the diagnosis of myelodysplastic syndromes (MDS) as well as a major indicator for predicting clinical course and outcome. This review concentrates on the cytogenetic classifications, the incidence and types of chromosome defects and the prognostic significance of the karyotype in adult primary MDS. Two cytogenetic classifications are currently used: one is based on the karyotype complexity (normal, single, double or complex defects), the other on clonal status (all metaphases normal, abnormal or admixture of normal and abnormal clones). Chromosome abnormalities are of both numerical and structural types. Aside from the 5q-syndrome, no specific clinico-cytogenetic entity has been reported. However, several distinct clinical and cellular features have been identified that correlate with the presence of specific chromosome defects such as inv(3)/t(3;3), +6, t(5;12), del(17p) and del(20q). The presence of complex defects is associated with reduced survival and a high risk of leukemic transformation. Among single defects, specific abnormalities may define distinct prognostic groups. Patients with del(5q) as a sole chromosome defect and a refractory anemia without excess of blasts have a favourable prognosis. For patients with trisomy 8 or monosomy 7 there may be distinct types of clinical evolution. Most patients with the 3q21q26 syndrome have a short survival. The presence of two chromosome defects may constitute an independent cytogenetic entity probably associated with relative poor prognosis. Karyotypic evolution generally represents a poor risk factor. The combination of cytogenetics with clinical and hematological features has proven to provide for a better prediction of patients' survival, leukemic transformation and response to treatment. Several scoring systems have been developed. They have to be improved by the study of new patients according to strict clinical and cytogenetic criteria and by the addition of newly recognized prognostic indicators such as histopathological features and molecular genetic mutations.

Myelodysplastic syndrome with t(5;12)(q31;p12-p13) and eosinophilia: a pediatric case with review of literature

PURPOSE

Myelodysplastic syndrome with chromosomal translocation t(5;12)(q31-33;p12-13) and eosinophilia is a new entity recently described. Nine cases have been described in adults. We report the first pediatric case with a long follow-up (7 years).

PATIENTS AND METHODS

An 8-year-old girl presented with hyperleukocytosis, eosinophilia, and no clinical symptoms. Bone marrow investigations revealed myeloid hyperplasia and clonal chromosomal translocation t(5;12)(q31;p12-13). No treatment was prescribed, but 4 years later the white blood cell count reached 144 X 10(9)/L with immature myeloid cells and splenic enlargement. Hydroxyurea chemotherapy led to a hematopoietic remission. The patient is now 16 years old and well, >7 years after the initial diagnosis.

RESULTS

The association: myelodysplastic syndrome, eosinophilia and translocation t(5;12)(q31-33;p12-13), seems to be a specific hematologic disorder. Study of cases previously reported in the literature shows the most important characteristics of this disease. However, there are still a number of questions about the disease itself (especially its treatment) and the significance of the chromosomal abnormalities.

CONCLUSION

This case seems to be the first report of the disease in a child and has had the longest follow-up. Other data should be collected to improve our knowledge of this hematopoietic disorder.

A new translocation, t(3;6)(q12;24) associated with chronic myelomonocytic leukaemia and marrow fibrosis

This report describes a 75-year-old man with chronic myelomonocytic leukaemia (CMML) and marked marrow fibrosis associated with t(3;6)(q12;24). Although structural abnormalities of 3q occur in haematological neoplasia, this particular chromosomal translocation has not been previously described in CMML. Karyotypic abnormalities involving 3q and marrow fibrosis may affect prognosis in CMML.

Translocation t(5;12)(q31-q33;p12-p13): a non-random translocation associated with a myeloid disorder with eosinophilia

A t(5;12)(q33;p13) translocation has been detected in two patients with myeloid disorder and eosinophilia. Six other patients with haematological disease with eosinophilia with similar translocation have been published previously. The existence of a new entity, a myeloproliferative disorder with eosinophilia and t(5;12) (q31-q33;p12-p13), is suggested by the results of the present study.

A case of myelodysplasia with eosinophilia having a translocation t(5;12) (q31;q13) restricted to myeloid cells but not involving eosinophils

A chromosomally abnormal clone characterized by a translocation, t(5;12)(q31;q13), was detected in the marrow of a child with myelodysplasia and associated eosinophilia which included a generalized skin infiltration. Combined immunophenotyping and fluorescence in situ hybridization on interphase bone marrow cells showed that the chromosomal rearrangement was restricted to the granulocyte lineage but was not present in the eosinophils. If the chromosome rearrangement is important in the overproduction of eosinophils in this case, the lineage restriction found suggests that its effect must be indirect.

Fusion of PDGF receptor beta to a novel ets-like gene, tel, in chronic myelomonocytic leukemia with t(5;12) chromosomal translocation

Chronic myelomonocytic leukemia (CMML) is a myelodysplastic syndrome characterized by abnormal clonal myeloid proliferation and by progression to acute myelogenous leukemia (AML). CMML thus offers an opportunity to study early genetic events in the transition to AML. A recently recognized subgroup of CMML has a t(5;12)(q33;p13) balanced translocation. We report that the consequence of the t(5;12) translocation is expression of a fusion transcript in which the tyrosine kinase domain of the platelet-derived growth factor receptor beta (PDGFR beta) on chromosome 5 is coupled to a novel ets-like gene, tel, on chromosome 12. The tel-PDGFR beta fusion demonstrates the oncogenic potential of PDGFR beta and may provide a paradigm for early events in the pathogenesis of AML.

Order of human hematopoietic growth factor and receptor genes on the long arm of chromosome 5, as determined by fluorescence in situ hybridization

A large number of human hematopoietic growth factor and growth factor receptor genes are localized at the long arm of chromosome 5. In this study we have determined the order of the human interleukin-3 (IL3), IL4, IL5, IL9, granulocyte macrophage-colony stimulating factor (GMCSF), and the MCSF receptor (MCSFR) genes by fluorescence in situ hybridization. Genomic lambda-clones were isolated using polymerase chain reaction (PCR)-generated probes and labeled with biotin and/or digoxigenin. These clones were first individually mapped: IL3, IL4, IL5, IL9, and GMCSF to 5q31 and MCSFR to 5q33. For ordering purposes multiple probe combinations were hybridized to metaphase chromosomes and interphase nuclei. The interphase hybridizations were evaluated by image analysis, which also allowed the measurement of the physical distance between the hybridization spots. These mapping results suggest the gene order 5cen-IL3/GMCSF-IL5-IL4-IL9-MCSFR+ ++-qter. The known genomic distance between the IL4 and IL5 genes allowed the estimation of the physical distances between the 5q31-specific genes, demonstrating that they are all within about 1.5 Mb of DNA.

Chronic myelomonocytic leukaemia (CMML)--a myelodysplastic or myeloproliferative syndrome?

Chronic myelomonocytic leukaemia (CMML), a disorder belonging to the group of myelodysplastic syndromes, has a number of peculiar features which raise the question as to whether it should be considered a distinct entity in its own right. The problems associated with its classification and diagnosis are discussed in this report using all currently available tools from clinical data to molecular genetics, including morphology, histology, cellular biology and cytogenetics. Three groups of patients can be identified (isolated monocytosis with a mild degree of dysplasia, severe cytopenia and the most frequent type with proliferative symptoms dominating the clinical picture). The latter group is close to atypical chronic myeloid leukaemia and perhaps these two entities should be regarded as a single one. Classification of the disease is further complicated by the possibility of evolution from one subgroup into another one and by the finding that CMML can also arise as a disorder secondary to other myeloproliferative (MPS) or myelodysplastic (MDS) syndromes. No specific marker of the disease has been identified by cytogenetics or molecular biology. Due to all these facts, we believe that CMML should perhaps be viewed more pragmatically by considering the use of prognostic factors that could at least help to define different groups of patients who may require different therapeutic strategies. We conclude that CMML is a heterogeneous syndrome with features of both MPS and MDS, encompassing primary and secondary stem cell disorders and varying widely in its clinical presentation. This heterogeneity should stimulate the search for reliable predictors of evolution which would allow a better definition of CMML subtypes based on prognostic factors.

t(5;12)(q31;p12). A clinical entity with features of both myeloid leukemia and chronic myelomonocytic leukemia

We report two patients with a myeloproliferative disorder (Philadelphia chromosome-negative chronic myeloid leukemia) and t(5;12)(q31;p12). Until now, only three cases of a translocation (5;12)(q31;p12) have been reported. All investigators had problems classifying their patient's disease into one of the well-defined entities of either MPD or myelodysplastic disorders. We postulate that this translocation may represent a subgroup of patients with features of both chronic myeloid leukemia and chronic myelomonocytic leukemia (CMMoL).

The biology of interleukin-5 and its receptor

IL-5 is primarily a T-cell-derived cytokine that has multiple regulatory functions on eosinophils and (in the mouse) on antibody-secreting B cells. A complex network of cytokines appear to control transcription of the gene for IL-5 and its production. Abnormally high levels of this cytokine are associated with infections with tissue-dwelling parasites and a diverse group of hypereosinophilic conditions of no known etiology. Our understanding of the biological role of IL-5 in the regulation of Ig production and the development of immunity to parasites is far from complete, but basic knowledge of its action at the cellular level is accumulating and will be critical for the intelligent application of immunotherapy with IL-5 or antibodies to IL-5 in infectious, neoplastic, and possibly other diseases.