Chromosome pattern, occupation, and clinical features in patients with acute nonlymphocytic leukemia

Poor survival in t(8;21) (q22;q22)-associated acute myeloid leukaemia with leukocytosis

Twenty-nine consecutive cases with a t(8;21)(q22;q22) in the bone marrow (BM) karyotype were retrospectively studied concerning clinical, morphological and cytogenetic data. All had been diagnosed as acute myeloid leukaemia (AML), 27 FAB subtype M2 and two M1, comprising 5% of all cytogenetically analysed AML during 18 yr. Auer rods were the most consistent t(8;21)-associated morphological finding and were demonstrated in 92% of the reviewed BM specimens, whereas BM eosinophilia was seen in only 24%. The median age was 53 yr, and 30% of the patients were > 60 yr old. Twenty-four patients had received induction chemotherapy; 22 of these (91%) entered a complete remission (CR). The median survival time in treated patients was 18 months. Leukocytosis at diagnosis (> or = 20 x 10(9)/1) was significantly (p = 0.01) associated with shorter survival time. All four children are still in first CR after 9-80 months. Seven cases (25%) developed granulocytic sarcomas, discovered either at diagnosis (n = 4) or at first relapse (n = 3). Secondary chromosome abnormalities were found in 62% of the cases, most often loss of a sex chromosome. The presence of such secondary aberrations did not correlate with any morphological or clinical characteristics, including survival. This first Scandinavian study of AML with t(8;21) corroborates the previous findings that these AMLs are characterized by distinct morphological features, a high frequency of CR and a striking tendency to develop extramedullary leukaemic manifestations. Leukocytosis at diagnosis indicates a less favourable prognosis.

Molecular epidemiology of hematological neoplasms--present status and future directions

The field of molecular epidemiology, using modern epidemiological approaches and taking the advantage of the advances in molecular biology can provide new tools for the exploration of etiological determinants, either environmental or hereditary, in the development of hematological neoplasms. It is now possible to identify some host susceptibility characteristics, to measure the effective dose of exposure, and to identify early, pre-clinical biological effects, using sensitive and specific biomarkers. The significant variation in the incidence of hematological neoplasms in different geographical areas, races, and age groups, the high rates of familial aggregation in certain populations, the involvement of protooncogenes and tumor suppressor genes in the development of hematological neoplasms, as well as of many environmental agents such as chemicals, radiation, and viruses, support the important role of molecular epidemiology in the investigation of the development of hematological neoplasms.

Monosomy 7 and 7q--associated with myeloid malignancy

An association between the complete or partial loss of chromosome 7 and preleukaemic myelodysplasia or acute myeloid leukaemia has been recognized from the early days of tumour cytogenetic analysis. Detection of such abnormalities usually heralds a poor prognosis. The loss of DNA on chromosome 7 has led to speculation that tumour-suppressor genes may play a significant role in this form of leukaemogenesis, although it may be part of a multistep process. A further association with leukaemia secondary to carcinogen exposure including previous chemotherapy or a number of congenital anaemias has increased the interest in discovering the gene or genes on chromosome 7. Banded chromosome analysis has suggested that there are two broad critical regions on the long arm of chromosome 7 at bands 7q22 and 7q34-q36 that may contain the relevant genes. Initial molecular analysis has confirmed these two regions to be of significance. The advent of fluorescence in-situ hybridization techniques has facilitated some definition of the 7q22 region, with identification of candidate genes for further functional analysis. It is becoming clear that there will be more than one gene on chromosome 7 involved in the leukaemic process and with the definition of these genes it may be possible to look for associations with different phenotypes and prognosis. As for the reason for chromosome 7 showing a particular predisposition to total or partial loss we may speculate that the DNA sequence and structure may confer a 'fragility' on the chromosome. A greater understanding of the DNA structure of the long arm may provide real insight into the mechanisms of leukaemia. We would like to speculate in the long term that this could lead to the ability to screen for leukaemia susceptibility and avoidance of 'inducers' in those at risk.

Monosomy X as a recurring sole cytogenetic abnormality associated with myelodysplastic diseases

Solitary loss of the X chromosome is associated with Turner syndrome and not hematological disorders. We describe five patients with non-constitutional loss of the X chromosome as the sole cytogenetic abnormality in their bone marrow. Three of the five patients had myelodysplastic syndrome (MDS), one case had AML M-6 with evidence suggestive of an evolving MDS, and the last patient had a dysplastic marrow. A review of the literature identified sporadic reports of an association of monosomy X and several hematologic disorders, as well as a few solid tumors. In this series of patients, monosomy X as a sole non-constitutional cytogenetic abnormality in bone marrow is associated with myelodysplastic diseases. In addition, fluorescence in situ hybridization analysis with an X centromere probe indicated that monosomy X was present in erythroid precursors, myeloblasts, promyelocytes, myelocytes, metamyelocytes, granulocytes, and monocytes, while mature lymphocytes presented with two copies of the X chromosome. The molecular cytogenetic evidence supports the diagnosis of a myelodysplastic disorder in these cases and documents the potential role of FISH in hematological disease.

Chromosome 7 and Haematological Malignancies

Abnormalities of chromosome 7 are the most common clonal chromosomal changes observed in myelodysplasia (MDS) and the second most frequent in acute myeloid leukaemia (AML) [1-5]. These changes may consist of long arm deletion (7q-) or total loss of the whole chromosome (monosomy 7) from bone marrow cells [1, 4, 6-24] and was first reported in association with myeloid disease in 1964 with the report of 3 cases of refractory anaemia, granulocytic hyperplasia [25]. The association between chromosome 7 alterations, MDS and AML in children and adults is clear, however, a rare association with lymphoid malignancies has also been recently reported. The abnormalities may occur in de novo MDS/AML, secondary cases following exposure to drugs, radiotherapy and toxins and in addition in a range of constitutional disorders including Fanconi's anaemia, congenital neutropenia and neurofibromatosis type 1 (NF1). The broad spread of conditions in which this consistent genetic change can occur leads one to speculate that there is an underlying instability in chromosome 7 and that genes on this chromosome play a role in the development of malignancy. The loss of DNA associated with malignant progression suggests the presence of a tumour suppressor gene (or genes) [26, 27]. Patients with monosomy 7 usually present as classical MDS with abnormal erythroid, megakaryocyte and myeloid differentiation [7, 28]. From a mechanistic perspective, increased cell proliferation and apoptosis is a common feature possibly induced by the failure of normal haematopoietic maturation. In all groups the presence of chromosome 7 abnormalities defines a poor prognostic group [29]. The majority of patients with MDS transform to a form of acute leukaemia resistant to therapy, including bone marrow transplantation (BMT). Although fluorescence in situ hybridization (FISH) has accelerated the study of these disorders at the cytogenetic and molecular levels, [4, 30, 31, 32, 33] no gene has been clearly implicated. A few candidate genes are under investigation. While the loss of chromsome 7 material is crutial in the malignant process it is almost certainly not the primary molecular abnormality. An initiating event genetic event predisposing to chromosome breakage and loss probably occurs in haematopoietic cells permitting chromosome 7 loss and progression to clonal malignancy as a secondary event.

A new translocation, t(5;21)(q13;q22) in acute myelogenous leukemia

We report a case of acute myelogenous leukemia with a variant translocation involving chromosomes 5 and 21 with breakpoints on 5q13 and 21q22 as revealed by various techniques including fluorescence in situ hybridization. The unusual presentation of t(5;21)(q13;q22), as the sole abnormality in acute myelogenous leukemia, is atypical.

Cytogenetic survey of 53 Moroccan patients with acute myeloblastic leukemia

We present a cytogenetic survey of chromosome aberrations for 53 Moroccan patients with acute myeloblastic leukemia (AML). Our 53 patients were 2 to 70 years old with 31 men and 22 women. The cytogenetic study was performed with the following three methods: first, relative proportion of normal (N) or abnormal (A) metaphases; second, presence of specific or random abnormalities; and third, karyotype complexity. Among 36 patients (67%) with a chromosomal abnormality, 18 (34%) showed a specific aberration. We have found t(9;22) in three patients (5%), chromosome 5 or 7 abnormality in six (11%), del(11)(q23) in three (6%), +21 in four (8%), and +8 in two (4%). Specific translocations associated with FAB type were found: t(8;21) with AML2 in 12 patients (23%) and t(9;11) with AML5 in one (2%). Rare abnormalities were also found: one patient with t(7;21) associated with AML2 and another patient with r(1) ring associated with AML1. We concluded that our study in a Moroccan population confirmed the relation between some specific abnormalities and the FAB classification. We have found a higher incidence for t(8;21) than usually described. Finally, we have identified chromosomal abnormalities t(7;21)(q22;p11) and r(1), rarely described before.

Genetic analysis of chromosome 13 deletions in BCR/ABL negative chronic myeloproliferative disorders

Chromosomal deletions of band 13q14 occur recurrently in BCR/ABL negative chronic myeloproliferative disorders (CMPD), including myelosclerosis with myeloid metaplasia (MMM), polycythemia vera (PV), essential thrombocythemia (ET), juvenile chronic myeloid leukemia (JCML), and the so-called BCR/ABL- chronic myeloid leukemia (CML). The RBI tumor suppressor locus, mapping to 13q14, has long since been hypothesized as the important gene. In this report, we have determined the frequency of 13q14 deletions at the molecular level in a large panel of BCR/ABL- CMPD at different disease stages and performed a detailed genetic analysis of gross rearrangements/deletions and point mutations of the RBI gene in these disorders. Our data show that molecular deletions of 13q14 are detected in a relatively large fraction of BCR/ABL- CMPD (38%), that they appear to be more frequent in MMM than in other BCR/ABL- CMPD, and that they may be present at diagnosis or occur during blastic evolution of the neoplasia. The RBI gene displayed a germline configuration in all BCR/ABL- CMPD tested, suggesting that 13q14 deletions in these disorders affect a tumor suppressor locus distinct from RBI.

Fluorescence in situ hybridization analysis of whole-arm 7;12 translocations in hematologic malignancies

Cytogenetic analysis of one case of acute myeloid leukemia (AML), one of acute lymphoblastic leukemia (ALL), one of refractory anemia with excess of blasts (RAEB), and one of acute mixed lineage leukemia (AMLL) with unbalanced 7;12 translocations mapped the breakpoints to the centromeres on both chromosomes. The rearrangements were interpreted as the whole-arm translocations der(7;12)(q10;q10) in the AML and ALL and der(7;12)(p10;q10) in the RAEB and AMLL. However, further analysis by metaphase and/or interphase fluorescence in situ hybridization (FISH) showed centric fusion only in the AML and ALL. In the RAEB and AMLL, centromeric material from chromosome 7 but not from 12 was present in the derivative chromosome. Whereas the t(7;12) resulted in loss of 12p in all four cases, the corresponding chromosome 7 imbalances differed--monosomy for 7q in the RAEB and AMLL and monosomy for 7p in the AML and ALL. Six hematologic neoplasms with unbalanced whole-arm or near-centromeric 7;12 translocations and seven dic(7;12) with juxtacentromeric breakpoints have been reported previously: 2 AML, 1 RAEB in transformation, and 10 ALL. All karyotypically informative cases had loss of 12p material. All but one of the cases with combined 7p and 12p deletion were ALL, whereas all cases with 7q and 12p loss showed myeloid differentiation. No particular clinical, morphologic, or immunophenotypic features seem to characterize ALLs with t(7;12). AMLs with an unbalanced t(7;12), often together with 5q deletions, might be associated with previous genotoxic exposure and poor prognosis.

12q13, a new recurrent breakpoint in acute non-lymphoblastic leukemia

The karyotypes of 312 successfully analyzed samples of children with acute non-lymphoblastic leukemia (ANLL), which were sent to us by 72 German hospitals, were examined in order to find new recurrent chromosome abnormalities of possible clinical relevance. Whereas most of the patients had one of the specific aberrations of ANLL or a normal karyotype, random numerical or structural changes were found in 61 children (20%). Four of them showed an abnormality involving band 12q13: t(12;17)(q13;q21), t(12;21)(q13;q21), t(2;12)(p13;q13), and t(5;12)(p11;q13). Despite the fact that FAB subtypes were different (M0, M1 M6, AHL), the blasts of all patients were characterized by immaturity and were difficult to classify. The breakpoint 12q13 might be of clinical importance in ANLL, because the four patients in our study, as well as the 21 patients with this aberration found in the literature, had a very poor prognosis.

Severe hypodiploidy with karyotype instability in a case of acute myeloid leukemia

We present a case of acute myeloid leukemia (AML) in an elderly male. A severe hypodiploid karyotype (chromosome range 29-39) was detected with a large amount of cell-to-cell variation, suggesting that the leukemic cells are primarily characterized by chromosomal loss due to karyotypic instability. Severe hypodiploidy is a rare finding in AML but previous similar cases indicate that it confers a very poor prognosis.

Hematopoietic malignancies and related disorders among benzene-exposed workers in China

Although the relationship between benzene and acute nonlymphocytic leukemia (ANLL) is well established, most of the analytic cohort investigations examining the relationship between benzene and hematologic neoplasms have evaluated only death certificates to validate diagnoses. In a follow-up study of 74,828 benzene-exposed and 35,805 non-exposed workers in China, pathology reports, medical records, and/or histopathologic material were reviewed for all patients with hematopoietic malignancies to ensure correct classification and to provide clinicopathologic descriptions. Eighty-two patients with hematopoietic neoplasms and related disorders were identified among benzene-exposed workers, including 32 cases of acute leukemia, 7--myelodysplastic syndrome (MDS), 9--chronic granulocytic leukemia (CGL), 20--malignant lymphoma or related disorder (ML), 9--aplastic anemia, and 5 others. Among the comparison group, 13 hematologic malignancies were observed, including 6 patients with acute leukemia, 2--CGL, 3--ML, and 2 others. The hematopathologic characteristics of the benzene-exposed ANLL cases resembled those following chemotherapy or radiotherapy. ANLL in workers exposed to benzene may represent a distinct clinicopathologic entity, with characteristics similar to treatment-related ANLL, including a preceding preleukemic phase in some patients. Results in our series, one of the largest to data, also indicate that a greater diversity of hematologic neoplasms is evident among benzene-exposed workers than previously described.

Cytogenetics in acute myeloid leukaemia

A wealth of literature spanning 20 years describing cytogenetic abnormalities in acute myeloid leukaemia (AML) already exists. It ranges from single case reports of unusual abnormalities to large multicentre studies of hundreds of cases. A landmark publication was the Fourth International Workshop on Chromosomes in Acute Leukaemia which established a base line for diagnosis, prognosis and frequency of chromosome abnormalities in AML. Two large sources of information are a book, 'The Chromosomes in Human Cancer and Leukemia' and a catalogue of chromosome abnormalities, which aims to list all chromosome abnormalities described in the scientific and medical literature from 1973, when the widespread use of banding techniques, enabled the precise definition of the chromosome breakpoints. In this review the common cytogenetic abnormalities seen in AML with reference to associations with the French-American-British (FAB) classification, their possible prognostic significance and their associated molecular biology are summarized.

A perspective on benzene leukemogenesis

Although benzene is best known as a compound that causes bone marrow depression leading to aplastic anemia in animals and humans, it also induces acute myelogenous leukemia in humans. The epidemiological evidence for leukemogenesis in humans is contrasted with the results of animal bioassays. This review focuses on several of the problems that face those investigators attempting to unravel the mechanism of benzene-induced leukemogenesis. Benzene metabolism is reviewed with the aim of suggesting metabolites that may play a role in the etiology of the disease. The data relating to the formation of DNA adducts and their potential significance are analyzed. The clastogenic activity of benzene is discussed both in terms of biomarkers of exposure and as a potential indication of leukemogenesis. In addition to chromosome aberrations, sister chromatid exchange, and micronucleus formation, the significance of chromosomal translocations is discussed. The mutagenic activity of benzene metabolites is reviewed and benzene is placed in perspective as a leukemogen with other carcinogens and the lack of leukemogenic activity by compounds of related structure is noted. Finally, a pathway from exposure to benzene to eventual leukemia is discussed in terms of biochemical mechanisms, the role of cytokines and related factors, latency, and expression of leukemia.

Age- and gender-related heterogeneity of cancer chromosome aberrations

The karyotype of a neoplasm is known to be associated not only with the histopathologic subtype of the tumor but also with previous cytotoxic exposure and with the geographic place of origin of the patient. Some data also indicate that cytogenetic patterns vary with age and gender. To further investigate whether the frequencies of cancer chromosome aberrations differ between children and adults or between men and women, clinical and karyologic data on 14,141 neoplasms with clonal chromosome changes reported in the literature were assessed. In cytogenetically well-characterized neoplasias, recognized primary and secondary chromosome aberrations were selected, and their frequencies were calculated in men, women, children (< or = 15 years), and adults (> 15 years). In general, the frequencies of the various aberrations did not differ between men and women or between children and adults, but a few exceptions were found. In refractory anemia (RA) and RA with excess of blasts or in transformation, del(5q) was more common among women. In acute lymphoblastic leukemia (ALL-L1 + L2), t(1;19) was more frequently detected in women and del(6q) more common among men. In Philadelphia chromosome positive chronic myeloid leukemia, gain of an extra der(22)t(9;22) occurred more frequently among men. Four primary aberrations were more common in children than in adults: t(8;21) in acute myeloid leukemia (AML-M2), -7 in AML-M4, der(11q) in AML-M5, and t(8;14) in ALL-L3. On the other hand, der(16q) in AML-M4 and t(9;22) in ALL-L1 + L2 were more common in adults. The only secondary cancer chromosome aberration showing a variation with age was loss of the Y chromosome in AML-M2 with t(8;21), being more common in children than in adults. These variations might be spurious and level out when more data are collected, but more probably they reflect, for reasons presently unknown, that different genetic mechanisms may be operative in children and adults--and even in men and women--in the development of some tumors.

Oligoclonal B-cell leukemia characterized by spontaneous cell division and telomere association

Cytogenetic analysis of unstimulated cultures from a female patient with chronic B-cell leukemia (CLL) revealed three cytogenetically distinct clones, suggesting that the patient's leukemia was oligoclonal. Immunoglobulin heavy chain gene rearrangement studies revealed 1 germline and 4 rearranged bands, indicative of an oligoclonal leukemic population. Further evidence of oligoclonality was provided by X-linked RFLP studies. This is the first report of oligoclonality in CLL demonstrated by cytogenetic, immunoglobulin gene rearrangement, and X-chromosome inactivation studies. In addition to oligoclonality, the patient's leukemic cells exhibited telomere association, a Robertsonian translocation, and clonal evolution, suggesting an underlying genomic instability.

Isochromosome 17q as a sole anomaly: a distinct myelodysplastic syndrome entity?

We report four patients with myelodysplastic syndrome (MDS) with isochromosome i(17q) as the sole chromosomal anomaly. One patient was classified as refractory anemia (RA) and three as refractory anemia with excess of blasts (RAEB). All four patients shared several features such as male sex, advanced age, severe anemia, as well as a bone marrow with myeloproliferative characteristics: hypercellularity, prominent baso- and eosinophilia, and marked increase of micromegakaryocytes. We suggest that patients with i(17q) as the sole chromosomal anomaly may identify a distinct MDS with characteristics between MDS and chronic myeloproliferative disorders (CMPD).

Incidence of chromosome abnormalities and clinical significance of karyotype in de novo acute myeloid leukemia

Cytogenetic studies with high-resolution banding were performed on specimens from 132 consecutive patients with de novo acute myeloid leukemia (AML). All patients were treated according to therapeutic protocols in the same institution. Clonal abnormalities were detected in 97 of the 124 patients in whom an adequate number of mitoses was obtained (78.2%). Neither sex, FAB classification, WBC, or the extent of bone marrow infiltrate affected the rate of chromosomal aberrations, whereas patients younger than 40 years had a greater proportion of normal karyotypes (p = 0.047). Two different chromosomal classifications were evaluated: the presence of normal and abnormal metaphases (NN-AN-AA classification), and a classification in cytogenetic categories, the latter being based on the frequency of cytogenetic abnormalities. Both classifications were found to correlate significantly with the clinical outcome. They also showed independent prognostic significance when age, sex, and FAB morphology were considered in a multivariate analysis. Two abnormalities were closely associated with specific clinical-pathologic subsets of AML. All the 15 patients with t(15;17) had acute promyelocytic leukemia; this translocation was not found in any other subset of AML. Eight of the nine patients presenting rearrangements at 11q23 belonged to a FAB subset with monocytic differentiation (M4 and M5). Our data suggest that cytogenetic findings should influence the therapeutic approach to AML. In particular, young patients with karyotypes associated with poor responses may be considered for more eradicating treatments, including allogenic bone marrow transplantation.

A new chromosomal anomaly associated with mature B-cell chronic lymphoproliferative disorders: del(7)(q32)

Among 63 patients with chronic lymphoproliferative disorders (CLPD) studied cytogenetically in our laboratory, four showed a del(7)(q32); in two it was the sole cytogenetic anomaly and in two it was part of a complex karyotype. We suggest that despite the rarity of this anomaly, it could be related to CLPD.

Morphologic, immunologic and cytogenetic studies in acute myeloid leukemia following occupational exposure to pesticides and organic solvents

In order to analyze the correlation between environmental exposure and the clinicopathological picture in acute myeloid leukemia (AML), cytogenetic, cyto-immunologic and clinical studies were performed in 70 newly diagnosed AML patients, 30 of which were anamnestically exposed to pesticides (21 cases) or to organic solvents (9 cases). Clonal chromosome aberrations, with involvement of chromosome 5 and/or 7 were more frequently encountered among exposed patients. While the classical t(15;17), t(8;21) and t(9;11) were detected more frequently among non-exposed patients, other recurring chromosome changes in the exposed group were: rearrangements leading to total or partial monosomy 17p (5 cases), structural aberrations involving the band 16q22 (4 cases), trisomy 11q (2 cases), breaks involving bands 6p23, 7p14, 11q13 (2 cases each). Cytologically, trilineage myelodysplasia was observed in 21 exposed patients, whereas morphologic aberrations of the non-blast cell population were confined to a minority of cells in most patients non-exposed. Immunologic studies revealed positivity for the CD34 stem cell marker in 80% exposed patients vs 22% in the non-exposed group. Conventional chemotherapy achieved complete remission in 3/21 patients exposed and in 16/32 patients non-exposed. Median survival was 2 months in the former group and 9 months in the latter group. These findings show that AML following occupational exposure to pesticides and organic solvents may represent a distinct cytogenetic and clinicopathological entity.

AML with unusual chromosomal changes. Translocation (15;21) and 5q- in the presence of two normal chromosomes 5

We performed serial cytogenetic studies of the bone marrow (BM) of a patient with acute myeloblastic leukemia (AML) and noted abnormal karyotypes 47,XY,+del(5)(q12q34),t(15;21)(q21;q22)/47,XY,+del(5)(q12q34 ) during the second relapse. Although a case of this t(15;21) was recently observed in a female patient with acute nonlymphocytic leukemia (ANLL) of subtype M4 of the French-American-British (FAB) classification, the present article constitutes the first report of its occurrence in association with ANLL of subtype M1-M2. Furthermore, the presence of the 5q- accompanied by two chromosomes 5 of normal appearance is very rare and of great interest.

Distinct cytogenetic and clinicopathologic features in acute myeloid leukemia after occupational exposure to pesticides and organic solvents

BACKGROUND

To study the correlation of environmental exposure to potentially mutagenic agents and the clinicopathologic picture in acute myeloid leukemia (AML), clinical features, morphologic characteristics, immunophenotype, and cytogenetics were studied in 59 patients with newly diagnosed AML.

METHODS

Based on interviews on occupational hazards and hobbies showing prolonged contact with pesticides (18 patients) and organic solvents (7 patients), 25 patients were categorized as "exposed". Thirty-four patients were categorized as "unexposed,", based on anamnestic findings.

RESULTS

Light microscopic studies showed myelodysplasia involving multiple cell lineages in all assessable patients with professional exposure to pesticides and organic solvents, whereas morphologic aberrations of the non-blast cell population were confined to a minority of cells in unexposed patients. These findings were confirmed by electron microscopic studies in 31 patients. Immunologic analysis showed the presence of a minor megakaryoblastic component in six exposed patients and showed positive findings for the CD34 stem cell marker in 85% of exposed patients, a figure significantly higher as compared with that for unexposed subjects. Cytogenetic studies confirmed the frequent occurrence of 5q and/or 7q aberrations in patients occupationally exposed (10 of 25 cases). Other recurring chromosome aberrations in the exposed group were 17p-, trisomy 11q, and translocation of 16q, 6p, 7p, and 11p, whereas the classic AML-specific translocations (i.e., t[15;17]; t[8;21]) were detected only in unexposed subjects. Conventional chemotherapy achieved complete remission in 1 of 19 exposed patients, as opposed to 14 of 29 unexposed patients, with a median survival of 2 months in the former group and 8 months in the latter.

CONCLUSIONS

Taken together, these findings document that AML in patients professionally exposed to toxic substances may represent a distinct cytogenetic and clinicopathologic entity. The clinicobiologic characteristics in these exposed patients are similar to the features of AML arising in patients with prior chemotherapy for another tumor, thus suggesting that similar transformation pathways may underlie leukemogenesis induced by cytotoxic drugs and by environmental exposure to some pesticides or organic solvents.

Peripheral blood chromosome aberrations in MDS

The frequency of non-clonal structural and numerical chromosome aberrations in peripheral blood lymphocytes of 51 patients with MDS and 37 age-matched hematologically normal subjects is assessed. The frequency of aneuploid cells (p less than 0.001) and of structural aberrations (p less than 0.005) was significantly higher in MDS patients than in normal subjects, but showed no relationship with FAB type or with the presence of clonal karyotype abnormalities in the bone marrow. Exchange configurations were only observed in MDS patients (27.5%). The data also suggest that there may be an association between high peripheral blood aberration levels and rapidly progressive disease. This may indicate increased mutagen sensitivity and have implications for treatment.

Deletion of chromosome 6q in two cases of acute myeloblastic leukemia and a review of the literature

Two cases of acute myeloblastic leukemia (AML M2) associated with a deletion of chromosome 6q are described. One was a 38-year-old man with constitutional inversion of chromosome 9, and another was a 57-year-old female atomic-bomb survivor. The karyotype of these patients were 46,XY,del(6)(q12q14),inv(9)(p11q13), and 47,XX,6q-,+min, respectively. In both cases c-myb protooncogene, which is located in chromosome 6q, was neither deleted nor rearranged, and c-myb messenger RNA level was not elevated. These results suggest that c-myb is not involved in the leukemogenesis of AML with 6q- as well as lymphoid malignancies with 6q-. Out of 23 AML cases with 6q- reviewed, 6 cases had erythroleukemia, and 4 developed in Down syndrome patients.

Exposure to organic solvents and risk of haematological malignancies

Epidemiological studies indicating that exposure to organic solvents is a risk factor for haematological malignancies are reviewed. Exposure to benzene is a risk factor for ANLL. A preleukaemic phase with pancytopenia is common and may be associated with a normo- or hypercellular marrow with morphological characteristics suggesting MDS. There are indications that other organic solvents than benzene may be leukaemogenic. Certain chromosome aberrations are characteristic in leukaemic cells from solvent exposed ANLL patients. The average latency time from start of occupational exposure until diagnosis is about 10-11 years. There is epidemiological evidence that exposure to organic solvents may also increase the risk of lymphoproliferative malignancies, i.e. ALL, NHL, HD and myeloma.

Acute monoblastic leukemia (FAB-M5b) with t(8;14)(p11;q11.1)

A case of acute monocytic leukemia (FAB-M5b) expressing natural killer cell-associated antigens containing a t(8;14)(p11;q11.1) is presented. We interpret this translocation to represent a variant of the t(8;16) previously reported in FAB-M5b. These findings support the contention that the 8p11 breakpoint site is the critical junction in the oncogenesis of acute monoblastic leukemia with differentiation.

Chromosome abnormalities and prognosis in childhood acute leukemia

We report here on the leukemic cell karyotypes of 134 children with acute nonlymphocytic leukemia (ANLL) examined at Saitama Children's Medical Center (SCMC), and of 88 children with acute lymphoblastic leukemia (ALL) referred to SCMC. The patients were mainly treated according to the protocol of the Tokyo Children's Cancer Study Group. Of 106 ANLL cases with adequate banding, 18% were normal, 34% had miscellaneous clonal abnormalities, and 48% were classified into known cytogenetic subgroups: t(8;21) (n = 21), 11q23 abnormalities (n = 14), -7/del(7q) (n = 6), inv (16)/del(16) (n = 5), and t(15;17) (n = 5). According to the FAB classification, M7 (21.7%) were more frequent than in previous reports because this study included a number of Down's Syndrome patients with M7 morphology. The present study confirmed the well-known association of t(15;17) with M3, t(8;21) with M2, 11q23 abnormalities with M4 and M5, and inv (16)/del(16) with M4. Patients with t(8;21) or inv (16)/del(16q) ANLL fared no better overall than the entire group. Of 51 ALL cases with adequate banding, 13.7% were normal, and 86.3% were classified into abnormal subgroups: translocation (n = 14), hyperdiploidy (greater than 50) (n = 13), and miscellaneous abnormalities (n = 17). Cases with hyperdiploidy (greater than 50) were restricted to a common phenotype and fared better overall than the entire group. Patients with translocation were found in all phenotypes, and had a poor prognosis. We concluded that childhood acute leukemia could be subgrouped according to karyotypic patterns, and that patients with translocations had a poor prognosis in ALL as well as ANLL.

Cytogenetics of secondary myelodysplasia (sMDS) and acute nonlymphocytic leukemia (sANLL)

76 cases of secondary myelodysplasia (sMDS) and acute non-lymphocytic leukemia (sANLL) were cytogenetically analyzed. Among the 36 sMDS patients, 13 (36%) had only normal karyotypes whereas 23 (64%) displayed clonal chromosomal abnormalities. The most common aberrations were -7, 5q-, -5, and +8. In 10 patients (43% of the cytogenetically aberrant cases), clones with only one anomaly, mostly 5q- or -7, were found. Of the 40 sANLL patients, normal karyotypes were detected in 10 (25%). Among the 30 (75%) abnormal cases, the most frequent aberrations were -7, -5, +8, 7q-, -17, and +21. 12 patients (40%) had clones with single abnormalities, most often -7. In 4 sANLL patients cytogenetically unrelated clones were detected. A survey of all previously published secondary hematologic neoplasias reveals that the most frequent abnormalities in sMDS are -7 (41%), 5q- (28%), and -5 (11%), followed by der(21q), +8, 7q-, der(12p), t(1;7), -12, -17, der(17p), der(3p), der(6p), and -18. Clones with single aberrations have been found in 45% of the cases and cytogenetically unrelated clones have been described in 6%. The most common abnormalities in sANLL are -7 (38%), 5q- (17%), -5 (15%), +8 (13%), and -17 (11%), followed by der(3q), der(11q), der(12p), -21, 7q-, -18, der(3p), der(17p), +21, der(21q), der(6p), and -16. 38% of the sANLL patients have had clones with only one aberration and 3% have had unrelated clones. The frequencies of these nonrandom abnormalities in sMDS and sANLL are thus remarkably similar - the only exception appears to be 5q-, which is more common in sMDS. Also the mean number of abnormalities per case is similar - 5.3 in sMDS and 5.6 in sANLL. When the incidences of characteristic cytogenetic abnormalities were correlated with the type of previous therapy, -7 was found to be more frequent in sMDS and sANLL patients who had been exposed to chemotherapy whereas 5q- was associated with previous exposure to ionizing radiation in sMDS patients.

Linkage mapping of the human CSF2 and IL3 genes

Interleukin 3 (encoded by the IL3 gene) and granulocyte-macrophage colony-stimulating factor (encoded by the CSF2 gene) are small secreted polypeptides that bind to specific cell surface receptors and regulate the growth, gene expression, and differentiation of many of the hematopoietic cell lineages, particularly nonlymphoid cells. The IL3 and CSF2 genes have been cloned and mapped to human chromosome bands 5q23-31. Only 10 kilobases of DNA separates the two genes, suggesting that they have a common origin and/or regulation. We have cloned 70 kilobases of genomic DNA that includes the IL3 and CSF2 genes, as well as flanking sequences, and report a physical map of this region. Several unique-sequence DNA segments have been identified in this region, and one of these fragments detects two restriction fragment length polymorphisms in DNA from unrelated Caucasians. Segregation of these DNA polymorphisms was followed in the Centre Etudé du Polymorphisme Humaine (CEPH) panel of 40 large three-generation pedigrees, and linkage was detected with 17 genetic markers previously typed in these families. Multipoint linkage analysis permits the placement of the region containing the IL3 and CSF2 structural genes on the recombination-genetic linkage map of chromosome 5q and thereby allows the role of these genes in leukemogenesis to be more critically examined.

Geographic heterogeneity of neoplasia-associated chromosome aberrations

Using a database comprising 13,266 cytogenetically abnormal neoplasms, the geographic heterogeneity of neoplasia-associated chromosomal abnormalities was investigated by comparing the frequencies of characteristic aberrations in consecutive series of patients with the same diagnosis. Significant frequency differences between geographic areas were found for the aberrations +8, i(17q), +19, and an additional Ph1 chromosome in chronic myeloid leukemia (CML); -5, 5q-, and +8 in acute nonlymphocytic leukemia (ANLL); t(8;21) in ANLL-M2; t(15;17) in ANLL-M3; 5q- and -7 in myelodysplastic syndromes (MDS); t(9;22) and +21 in acute lymphocytic leukemia (ALL); t(14;18) in follicular lymphoma; -8 and -22/22q- in meningioma; and structural abnormalities of 12q in pleomorphic adenoma of the salivary glands (PAS). No geographic incidence variation was detected for -7 and +21 in ANLL; +8 in MDS; 6q- and +8 in ALL; +12 in chronic lymphocytic leukemia; 6q- in non-Hodgkin's lymphoma (NHL); t(8;14) in Burkitt's lymphoma; t(11;22) in Ewing's sarcoma; i(12p) in germ cell tumors; 1p- in neuroblastoma; structural abnormalities of 3q, 8q, and 9p in PAS; or 3p- in renal cell carcinoma. Intraregional frequency similarities between cytogenetically identical abnormalities in related tumor types were also analyzed. No significant correlations were found regarding the incidence of 5q- in ANLL and MDS, 6q- in ALL and NHL, -7 in ANLL and MDS, +8 in ANLL and CML, +8 in ANLL and MDS, +8 in ALL and ANLL, or +21 in ALL and ANLL. The findings indicate that some geographic heterogeneity of tumor-associated aberrations exists both in hematologic neoplasms and in solid tumors.(ABSTRACT TRUNCATED AT 250 WORDS)

Two Cases of Translocation t(3;6)(p14;p22): A Non Random Chromosomal Abnormality?

It is generally accepted that the short arm of chromosome 6 is a likely site to be involved in chromosomal rearrangements of MDS/ANLL following radio/chemotherapy. We report here two cases of t(3;6)(p14;p22). One patient is a 55 years old male with a previous history of occupational exposure who developed, an acute megakaryoblastic leukemia after a preleukemic phase. Chromosome analysis showed a t(3;6)(p14;p22), associated with del (5)(q14q31), -7, with variations and a trend to hypoploidy. The second patient is a 33 years old man, with chronic myeloid leukemia treated with Hydroxyurea (HU), HU + $aL-IFN and $aL-IFN alone. The first cytogenetic study before treatment, showed a t(9;22)(q34;q11). In the following months the patient had simultaneously t(9;22)(q34;q11) + t(3;6)(p14;p22) in a minority and thereafter in all the mitoses, with progressive deterioration, megakaryocyte abnormalities, but no blast crisis. Our patients are compared with the only 5 other published cases with t(3;6)(p14;p22), who shared some common features, namely a past history of chemo/radiotherapy or exposure to chemical mutagens and an association with other, so-called "secondary" chromosome aberrations, on segments 3p, 5q, 7q, 12p and 17p. We suggest that this uncommon translocation t(3;6) is nonrandom. It is worth noting that band 6p21 is the site of pim 1 oncogen, and that a fragile site is located on band 3p14.

Morphologic, immunologic and cytogenetic studies in erythroleukaemia: evidence for multilineage involvement and identification of two distinct cytogenetic-clinicopathological types

Clinical features, as well as morphology, immunophenotype and cytogenetics were retrospectively studied in 20 patients with an original diagnosis of erythroleukaemia (EL) reclassified according to the FAB criteria. Fifteen patients had de novo EL, five patients had therapy-related EL. Myelodysplasia preceded the onset of EL in eight cases and myelodysplastic features involving multiple haemopoietic lineages were observed at leukaemia presentation in all cases. Immunologic findings confirmed multilineage involvement, showing sub-population of cells expressing platelet-associated markers in more than 50% of cases tested and the presence of a myelomonocytic component, besides glycophorin A-positive cells. Cytogenetically, major karyotype aberrations (MAKA), defined by the presence of three or more aberrant events in the same clone, were observed in 14 cases, minor karyotype aberrations (MIKA) were observed in four cases and normal karyotype in two cases. No differences in the cytological-cytogenetic picture of our patients with de novo EL, and with therapy-related EL were found suggesting that aetiological factors and/or pathogenetic mechanisms common to EL and secondary leukaemia may exist. All patients with MAKA had leftward shift of erythropoiesis with proerythroblasts and basophilic erythroblasts usually representing more than 50% of all erythroid cells. In patients with MIKA or normal karyotype, maturatio of erythroid cells, though morphologically abnormal, was quantitatively preserved and early erythroblasts never exceeded 25% of erythroid cells. Clinically, the haemoglobin level at presentation, as well as in the proportion of patients achieving complete remission after chemotherapy, appeared to be lower in the maturation arrest-MAKA group as compared to the preserved maturation-MIKA/normal karyotype group. Median survival was shorter in the former group (3.5 months) than in the latter (median 13 months). Morphologic-immunologic-cytogenetic studies thus allow for the identification of two distinct cytogenetic-clinicopathological types of EL.

Acute nonlymphocytic leukemia (ANLL) with isochromosome i(17q) as the sole chromosomal anomaly: a distinct entity?

3 patients with acute nonlymphocytic leukemia (ANLL) and an isochromosome (17q) as the sole chromosomal defect are reported. Besides this cytogenetic pattern, they shared several clinical and hematological features such as male sex, advanced age, spleno- and/or hepatomegaly and a suspected preceding myeloproliferative syndrome. Bone marrow cytology was characterized by hypercellularity, prominent baso- and eosinophilia, decreased erythropoiesis and marked increase of dysmorphic megakaryocytes. We suggest that some or most patients with ANLL and i(17q) as the sole cytogenetic defect represent blastic transformation of an underlying chronic myeloproliferative disorder rather than de novo ANLL.

Acquired Robertsonian translocations in hematologic malignancy. A rare mechanism of clonal evolution

We identified three patients with an acquired Robertsonian translocation among 1,200 patients with hematopoietic malignancy. In each case the translocation served to produce partial chromosomal trisomy or tetrasomy within the malignant clone. Acquired Robertsonian translocation represents another, although rare, mechanism of clonal evolution in malignant cells.

TPR-MET oncogenic rearrangement: detection by polymerase chain reaction amplification of the transcript and expression in human tumor cell lines

Activation of the MET protooncogene by a rearrangement involving the fusion of TPR and MET specific gene sequences has been observed in a human osteosarcoma cell line (HOS) treated in vitro with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). No information has been available about the possible occurrence of this rearrangement in human tumors. To facilitate rapid screening of human cell lines and tumor samples for this specific gene rearrangement, we developed a sensitive detection method based on polymerase chain reaction (PCR) amplification of TPR-MET mRNA. cDNA was generated from cellular transcripts by using one of the PCR primers, which was then used as a template for PCR amplification of a 205-base-pair region carrying the breakpoint. An end-labeled internal probe was hybridized in solution to an aliquot of the PCR product for detecting amplification. Cells could be directly screened by the assay without prior isolation of RNA. A 205-base-pair DNA fragment characteristic of the TPR-MET rearrangement was detected in cell lines previously known to contain this altered sequence. The rearrangement was also detected at very low levels in the parental (nontransformed) cell line, HOS TE-85. A preliminary survey of cell lines derived from a variety of human tumors indicates that TPR-MET rearrangement occurred and was expressed at very low frequencies by cells from 7 of 14 tumors of nonhematopoietic origin.

Is trisomy 22 in acute myeloid leukemia a primary abnormality or only a secondary change associated with inversion 16?

In an attempt to confirm the existence of acute myeloid leukemia (AML) with trisomy 22, we studied three patients in whom trisomy 22 imposed as the sole karyotype abnormality. After revision of the karyotypes, however, we were able to identify an inv(16) as the important primary abnormality in all of them. Based on this experience, we investigated whether at least some of the 17 AML cases with trisomy 22 reported so far might possibly have been misinterpreted. Interestingly, ten out of 16 evaluable cases were classified as M4, some of them with bone marrow eosinophilia. As in cases with inv(16), only few metaphases contained trisomy 22. Furthermore, in at least two out of the only four published karyotypes of cases with trisomy 22, an inv(16) is evident and in the other two cases it cannot be ruled out. We therefore believe that at least some of the trisomy 22 cases mentioned in the literature are in fact only secondary changes occurring in AML with an inv(16) and suggest that future reports of AML with trisomy 22 as a specific primary abnormality can only be accepted as such if inv(16) has been excluded with appropriate methods.

Cytogenetics of childhood acute nonlymphocytic leukemia

Interest in more precise subclassification of the acute leukemias by cytogenetic criteria led us to identify and characterize the full range of chromosomal abnormalities in 121 children with de novo acute nonlymphocytic leukemia (ANLL). Only 21% of the cases had normal karyotypes; 62% had consistent or recurrent alterations, most commonly inv(16) or del(16), t(8;21), t(15;17), t(9;11), t(11;V) or del(11), and -7 or 7q-; and 17% had miscellaneous, apparently random, clonal abnormalities. Statistically significant associations between chromosomal abnormalities and the morphologic/cytochemical subtypes of ANLL, defined by criteria of the French-American-British (FAB) cooperative group were demonstrated for the t(8;21) in M1 and M2 leukemia, t(15;17) in M3, t(9;11) in M5, and translocations involving 11q23 other than t(9;11) [t(11;V)] or del(11q) in M4 and M5. The chromosome 16 inversion was not restricted to the M4 subtype, as is generally reported, and was not uniformly associated with increased and/or abnormal marrow eosinophils. None of these 121 cases were characterized by the Philadelphia chromosome, nor did any have the t(6;9), t(16;16), or inv(3), which have been noted previously in this disease. In addition to confirming several recognized correlations between recurrent structural chromosome abnormalities and FAB subtypes, this study identified novel abnormalities that have not been reported by others. It also disclosed an unusual heterogeneity of chromosome 16 abnormalities with respect to their distribution among FAB subtypes, their association with marrow eosinophilia, and their participation with other chromosomes in translocations.

Involvement of bands 9q21-q22 in five cases of acute nonlymphocytic leukemia

Five patients with acute nonlymphocytic leukemia (ANLL) with chromosomal aberrations involving bands 9q21-q22 are described. The abnormalities were an interstitial deletion in two cases of ANLL FAB type M4 and M4 with eosinophilia, a terminal deletion in two cases of M4 and M5 type ANLL, and a translocation in an M2 ANLL. A review of reported cases of ANLL with abnormalities of chromosome 9 revealed a clustering of breaks at the region 9q21-q22, suggesting a possible role for these bands in leukemogenesis.

Occupational history and involvement of chromosomes 5 and 7 in acute nonlymphocytic leukemia

We compared the histories of exposure to leukemogens for two groups of patients presenting with myelodysplastic syndrome (MDS) or acute nonlymphocytic leukemia (ANLL). In one group there were 59 patients with an acquired abnormality of chromosomes 5 or 7 in the marrow at time of diagnosis. In the other group there were 39 patients with a normal marrow karyotype at the time of diagnosis. A much higher proportion of the chromosomally abnormal cases had a history of treatment for a previous malignancy (odds ratio = 13.0, p less than 0.01). There was little difference found between the occupational histories of the patients with de novo ANLL with and without cytogenetic abnormalities. An occupational history of exposure to chemicals or metals was more common in males with either a deletion of the long arm of chromosome 7 or with monosomy 7 or monosomy 5 (82.3%) than in males with a normal karyotype (52.1%). The odds ratios did not, however, reach statistical significance.

Relation between occupational exposure to organic solvents and chromosome aberrations in non-Hodgkin's lymphoma

Chromosome analysis of lymphoma cells was performed in 54 untreated patients with non-Hodgkin's lymphoma (NHL). 10 patients had a history of daily occupational handling of organic solvents for at least 1 year (exposed group) and 44 patients had never (or only for shorter periods) worked with solvents (unexposed group). There were no differences between exposed and unexposed patients regarding age, clinical stage or histologic malignancy grade. The patients were assigned to three categories: Patients with 0-4, 5-9, or greater than or equal to 10 cytogenetic events producing clonal aberrations of the lymphoma cells. The proportions of exposed patients in these categories were 2/26 (8%), 5/20 (25%) and 3/8 (38%); respectively, i.e. with increasing numbers of events there was an increasing probability of previous exposure to solvents (p = 0.035, trend analysis). 5 of 7 exposed patients (71%) with intermediate or high-grade lymphomas displayed translocations involving the band 14q32. Such 14q+ markers were found in only 5 out of 28 unexposed patients (18%) with lymphomas of comparable malignancy grade (p = 0.01). Among unexposed patients with intermediate or high-grade lymphoma the most common clonal aberration was 6q- which occurred in 10 out of 28 patients (36%). This abnormality was not observed in the exposed patients with lymphomas of corresponding malignancy grades (p = 0.08). It thus appears that the number of clonal chromosome aberrations is especially large in NHL patients with a history of occupational exposure to organic solvents. Moreover, such exposure may be associated with characteristic cytogenetic changes in the lymphoma cells.

A t(3;5) in blastic phase of a Philadelphia chromosome-negative chronic myeloid leukemia

Serial cytogenetic analyses from the bone marrow of a patient with blastic phase of a Philadelphia chromosome-negative chronic myeloid leukemia revealed a t(3;5)(p21;q31). The literature on translocations involving chromosome 3 and the long arm of chromosome 5 is reviewed. The importance of breakpoints in band 5q31 is discussed.