Preleukemia and leukemia with 12p- and 19q+ chromosome alterations following Alkeran therapy

Inversion of chromosome 12 and lineage promiscuity in hematologic malignancies

Rearrangements of the short arm of chromosome 12 are among the most common aberrations found in hematologic malignancies, including myelodysplastic syndromes, acute myelocytic leukemias, acute lymphoblastic leukemias, and non-Hodgkin lymphomas. We report on a group of 46 patients with a variety of myelocytic and lymphoid malignancies, all with an inversion of chromosome 12. Both pericentric and paracentric inversions occurred. The identified hotspots for breakage were p13 and q24. These correspond to gene-rich areas of known chromosome instability. The inv(12) is difficult to detect and may be misinterpreted as a partial deletion by routine cytogenetics. Fluorescence in situ hybridization studies revised the G-banding interpretations of a deleted 12p in some cases to an inversion. The inv(12) may occur as the sole abnormality in both myelocytic and lymphoid malignancies, suggesting lineage promiscuity as seen with MLL and ETV6 gene disruptions. The majority of patients with the inv(12) had complex karyotypic changes that predicted a poor prognosis. Of the 24 patients with known clinical follow-up, many were refractory to chemotherapy and overall survival was short.

Comparative genomic hybridization detects multiple chromosomal amplifications and deletions in undifferentiated embryonal sarcoma of the liver

Undifferentiated embryonal sarcoma (UES) is the third most common hepatic malignancy in children. Previous reports have described a broad range of complex cytogenetic abnormalities in individual cases of hepatic UES. Herein we report the cytogenetic findings of six cases of hepatic UES at our institution analyzed by conventional cytogenetic methods and comparative genomic hybridization (CGH). The CGH demonstrated several chromosomal gains and deletions in each case, but there was no specific abnormality seen in every case. Patterns of chromosomal changes included gains of chromosome 1q (four cases), 5p (four cases), 6q (four cases), 8p (three cases), and 12q (three cases), and losses of chromosome 9p (two cases), 11p (two cases), and chromosome 14 (three cases). The three cases in which CGH showed gains in the 12q region were studied specifically for amplifications of MDM2 and CDK4, two genes that have been shown to be amplified in other soft tissue sarcomas. However, Southern analysis showed no amplification of MDM2 or CDK4 in these three cases. Further analysis will be needed to determine the critical events in the pathogenesis of these malignant pediatric liver tumors.

Incidence, characterization and prognostic significance of chromosomal abnormalities in 640 patients with primary myelodysplastic syndromes. Grupo Cooperativo Español de Citogenética Hematológica

Recently, a consensus International Prognostic Scoring System (IPSS) for predicting outcome and planning therapy in the myelodysplastic syndromes (MDS) has been developed. However, the intermediate-risk cytogenetic subgroup defined by the IPSS includes a miscellaneous number of different single abnormalities for which real prognosis at present is uncertain. The main aims of this study were to evaluate in an independent series the prognostic value of the IPSS and to identify chromosomal abnormalities with a previously unrecognized good or poor prognosis in 640 patients. In univariate analyses, cases with single 1q abnormalities experienced poor survival, whereas those with trisomy 8 had a higher risk of acute leukaemic transformation than the remaining patients (P = 0.004 and P = 0.009 respectively). Patients with single del(12p) had a similar survival to patients with a normal karyotype and showed some trend for a better survival than other cases belonging to the IPSS intermediate-risk cytogenetic subgroup (P = 0.045). Multivariate analyses demonstrated that IPSS cytogenetic prognostic subgroup, proportion of bone marrow blasts and haemoglobin level were the main prognostic factors for survival, and the first two characteristics and platelet count were the best predictors of acute leukaemic transformation risk. A large international co-operative study should be carried out to clarify these findings.

Correlation of cytogenetic, molecular cytogenetic, and clinical findings in 59 patients with ANLL or MDS and abnormalities of the short arm of chromosome 12

Abnormalities of the short arm of chromosome 12 (12p) are found in about 5% of acute nonlymphocytic leukaemias (ANLL) and myelodysplastic syndromes (MDS). They are described to be characteristic of secondary leukaemias, especially after prior mutagenic exposure, and to be associated with a poor prognosis. In our series of 59 patients with 12p abnormalities and ANLL or MDS, exposure to genotoxic agents was proven only in five patients, but in 13/44 patients ANLL evolved from an MDS. Patients with a small deletion del(12)(p11.2p13) having a mild clinical course were distinguished from those with a large del(12)(p11.2), additional chromosomal anomalies, and a poor clinical course. Among the 31 patients with translocations or dicentric chromosomes involving 12p, a group of eight with t/dic(12;13) was the most frequent and was associated with a poor prognosis. The clinical outcome was adverse in the majority of patients with complex karyotype abnormalities, but in some patients a milder clinical course seems likely. A new, hitherto undescribed, abnormality in an MDS case with a duplication dup(12)(p11.2p13) was the amplification of the signal of the yeast artificial chromosome (YAC) clone 964c10 (D12S736). In 38 cases with deletions or unbalanced translocations/dicentrics one YAC signal was lost. Five patients with balanced translocations demonstrated breakpoints within the YAC, containing the ETV6 (TEL) gene. The breakpoints were telomeric to the YAC 964c10 in seven cases and centromeric in one patient.

dic(5;17): a recurring abnormality in malignant myeloid disorders associated with mutations of TP53

We have identified three unbalanced translocations involving chromosomes 5 and 17, der(5)t(5;17), der(17)t(5;17), and dic(5;17), in the malignant cells from 17 patients with myeloid neoplasms. Six patients had a primary myelodysplastic syndrome (MDS) or acute myeloid leukemia (AML) de novo; ten patients had therapy-related MDS and/or AML (t-MDS/t-AML), and one patient had chronic myelogenous leukemia in myeloid blast phase. Two of the six patients with MDS or AML de novo had extensive exposure to industrial solvents, and one patient had Seckel syndrome. The primary diagnoses for the ten patients with t-MDS/t-AML were breast carcinoma and Hodgkin's disease in two patients each, and non-Hodgkin's lymphoma, multiple myeloma, chronic lymphocytic leukemia, ovarian carcinoma, thyroid carcinoma, and rhabdomyosarcoma in one patient each. Four patients had received both prior chemotherapy and radiotherapy, four others received prior chemotherapy only, and the remaining two patients only prior radiotherapy. Fluorescence in situ hybridization of centromere-specific probes for chromosomes 5 and 17 revealed that a dicentric rearrangement was the most common (13/16 patients examined). The genetic consequences of these chromosomal rearrangements are partial monosomy for 5q and 17p. Two of six patients examined had point mutations in TP53, suggesting that loss of function of TP53 in addition to loss of a tumor suppressor gene on 5q may be involved in the pathogenesis of the malignant disease in some of these patients.

Translocation (12;22)(p13;q12) as sole karyotypic abnormality in a patient with nonlymphocytic leukemia

Cytogenetic analysis of unstimulated bone marrow (BM) and peripheral blood (PB) cells of a patient with clinical features of atypical chronic myeloid leukemia (CML) showed t(12;22)(p13;q12) as the sole karyotypic abnormality. Subsequent fluorescence in situ hybridization (FISH) with abl- and bcr-specific cosmids as well as chromosome 12- and 22-specific DNA libraries and Southern blot analysis confirmed that in this patient t(12;22) does not constitute a cryptic Ph variant. Recently, a few very similar cases were reported by other investigations. The possible significance of this translocation as a new cytogenetic marker for nonlymphocytic leukemia is discussed.

Specific chromosomal translocations and therapy-related leukemia induced by bimolane therapy for psoriasis

This paper reports for the first time results of cytogenetic studies on 14 consecutive secondary acute non-lymphocytic leukemia (S-ANLL) induced by bimolane therapy. They included 10 males and 4 females with ages ranging from 17 to 54 years. They had all suffered from psoriasis and received bimolane treatment before the occurrence of their leukemia. The total dose of bimolane ranged from 40 to 400 g (mean dose 194 g). The interval between the initiation of bimolane therapy and the diagnosis of leukemia was 12-96 months (median 30 months). A preleukemic phase was only found in one case. No dysplastic features in the hemopoietic series were seen in any patient. Chromosome analysis of bone marrow cells using banding techniques revealed clonal karyotypic abnormalities in all cases: t(15;17) in 8 cases of M3, of which 75% had extra abnormalities, t(8;21) in 4 cases of M2, del(7q) only in one case of M4 and one case of M5. After antileukemic therapy, complete remission was obtained in 10 out of 12 cases with specific translocations and one out of 2 cases with 7q-anomaly, respectively. The former survived 4-58 months (median 12 months), while the latter 1 and 9 months, respectively. This study indicates that: (1) bimolane is a causative factor of leukemia in this series; (2) the leukemia in our series is therapy-related leukemia (TRL) rather than de novo ANLL; (3) there exists, in fact, a new subgroup of TRL characterized by specific rearrangements, whose clinical, hematological and prognostic features and pathogenetic mechanism may be different from classical TRL characterized by chromosome abnormalities involving absence or deletion of parts of chromosome 5 and/or 7.

Cytogenetic studies in 112 cases of untreated myelodysplastic syndromes

Cytogenetic studies were performed in 112 untreated cases of myelodysplastic syndrome (MDS) between 1985 and 1990. Among 112 patients who were examined at the time of diagnosis, 54 had an abnormal karyotype (48%). The highest frequency of chromosome abnormalities was observed in refractory anemia with excess of blasts (RAEB) and RAEB in transformation (RAEB-t) and the lowest in refractory anemia with ring sideroblasts (RARS) and chronic myelomonocytic leukemia (CMMoL). Numerical changes were observed in 19 cases and structural in 17; chromosome 8 was most frequently gained (11 cases), whereas chromosome 7 was most frequently lost (6 cases), 5q- in 14 (4 as a sole anomaly); involvement of 7q22 was seen in 3 cases, 11p in 2 patients, 11q in 3 (one patient as a sole anomaly), 12p in 4 (2 patients as a sole anomaly), i(17q) in 4 (3 patients as a sole anomaly), and complex chromosomal defects in 10 patients. If one takes into account the prognosis value, a complex karyotype and the presence of ring chromosomes were correlated with the worst prognosis, followed by -7/7q-; an intermediate prognosis corresponds to i(17q), 12p as a sole anomaly, +8 (as a sole anomaly or plus other anomalies), and involvement of 12p. Patients with a 5q- as a sole anomaly or with a normal karyotype, had the best prognosis.

Translocations involving 12p in acute myeloid leukemia: association with prior myelodysplasia and exposure to mutagenic agents. United Kingdom Cancer Cytogenetics Group (UKCCG)

Six cases of acute myeloid leukemia (AML) with translocations involving 12p are described. The patients were one child age 7 yrs and five adults with an age range of 20-66 yrs (median 46 yrs). In two patients AML followed treatment for acute lymphoblastic leukemia (ALL), in one case after 11 years disease-free survival. Of the remaining four patients, two had been occupationally exposed to possible mutagens and three had a previous myelodysplastic phase. Two patients achieved complete remission; survival for the six cases was between 1 and 24 months (median 6.5 months). The breakpoints in 12p occurred in p11, p12, and p13, indicating that several sites are important in these rearrangements, and it is suggested that t(12;17)(p11;q11) is a new nonrandom abnormality in AML.

Deletion 12p in de novo acute myeloid leukemia. An association with early progenitor cell

Deletion of the short arm of chromosome 12 as the sole karyotypic abnormality was found in three cases of acute myeloblastic leukemia (AML). In contrast to what has previously been reported in the literature, none of our cases had an antecedent history of myelodysplasia or toxic exposure, and basophilia was absent. Two cases were terminal deoxynucleotidyl transferase (TdT) positive, suggesting involvement of an early progenitor cell.

Chromosomal localization of an SH2-containing tyrosine phosphatase (PTPN6)

We have used panels of somatic cell hybrids and fluorescent in situ hybridization to determine the chromosomal localization of the novel nontransmembrane tyrosine phosphatase PTPN6 (protein tyrosine phosphatase, nonreceptor type 6), which contains two SH2 domains. PTPN6 maps to 12p13, a region commonly involved in leukemia-associated chromosomal abnormalities. Since PTPN6 is expressed at high levels in hematopoietic cells of all lineages and its expression is induced early in hematopoietic differentiation, altered expression and/or structure of PTPN6 may play a role in leukemogenesis.

Cytogenetic and clinical findings of myelodysplastic syndromes with a poor prognosis. An experience with 97 cases

BACKGROUND

Clinical and cytogenetic analyses were performed in 97 patients with myelodysplastic syndromes (MDS) to evaluate risk factors for poor prognosis.

METHODS/RESULTS

Among them, 22 patients survived for less than 1 year: 10 of these had complex chromosomal abnormalities (complex aberrations), but only 5 of the remaining 75 patients who survived longer than 12 months did. Leukemia did not develop in approximately half of the patients who died within 1 year. The occurrence rate of leukemic transformation appears to depend on MDS subtypes rather than cytogenetic changes. In contrast, the percentage of patients who survived for less than 1 year is related to chromosomal changes, especially to complex aberrations. Of particular interest in this study is that 7 of 11 patients with MDS who had myelofibrosis survived for less than 1 year, and 5 of 7 patients with secondary MDS were included in this group showing a poor prognosis. By hematologic analysis, significant differences were found in the hemoglobin values and platelet counts of patients who survived for less than 1 year.

CONCLUSIONS

From this analysis, three major risk factors for a poor prognosis were identified: complex aberrations, a history of chemotherapy or radiation therapy (secondary MDS), and development of myelofibrosis. The survival probability in the patients with MDS having at least one of these three factors was significantly low when compared with that in patients without these factors, indicating that cytogenetic analysis in combination with observance of certain clinical manifestations is important in therapeutic management of patients with MDS.

Secondary myelodysplastic syndrome complicating therapy for osteogenic sarcoma

A 12-year-old girl with nonmetastatic osteogenic sarcoma received treatment with doxorubicin, methotrexate, cisplatin, cyclophosphamide, bleomycin, and dactinomycin. She developed unexplained persistent pancytopenia after completion of chemotherapy. Twenty-three months after the initial diagnosis of osteosarcoma an evaluation revealed a bone marrow pattern consistent with the diagnosis of refractory anemia with excess blasts, and karyotype analysis showed characteristic findings of therapy-related myelodysplasia (loss of chromosomes 5 and 7, as well as 12p and 17p deletions). Bone marrow transplantation from an human leukocyte antigen (HLA)-compatible sibling donor was performed 26 months after the diagnosis of the primary malignancy. Although it is unproven that the alkylating agents administered to this patient were responsible for the myelodysplastic syndrome, careful follow-up of osteosarcoma patients who receive alkylating agents is warranted.

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.

Trisomy 8 and an unbalanced t(5;17)(q11;p11) characterize two karyotypically independent clones in a case of idiopathic myelofibrosis evolving to acute nonlymphoid leukemia

In a patient with idiopathic myelofibrosis (MFI) that had progressed to acute nonlymphoid leukemia (ANLL) after a long-lasting cytotoxic treatment, we observed two karyotypically independent cell populations, one showing trisomy of chromosome 8 as the only anomaly and one with an unbalanced translocation t(5;17)(q11) resulting in partial monosomy of 5q and 17p. The overall karyotypic configuration suggested that chromosome changes occurred as secondary events during the multistep process of leukemogenesis. The probable sequence of cytogenetic events in this patient and a review of the literature indicated that the t(5;17) may represent a therapy-induced abnormality nonrandomly related to the terminal phase of myeloid disorders.

The human VAV proto-oncogene maps to chromosome region 19p12----19p13.2

A novel human oncogene, designated VAV, has been recently characterized. This oncogene was generated by a rearrangement within the 5' coding sequences of a normal cellular gene, the VAV proto-oncogene. The normal VAV gene is specifically expressed in hematopoietic cells regardless of their differentiation lineage. We now report that the VAV locus has been localized in the human genome at chromosome 19p12----19p13.2 by analysis of its segregation pattern in rodent-human somatic cell hybrids and by chromosomal in situ hybridization. The VAV locus might be closely linked to the insulin receptor (INSR) locus, as suggested by comigration of INSR and VAV high-molecular-weight DNA fragments after pulsed-field gel electrophoresis. The VAV chromosomal assignment is of interest because chromosome region 19p13 is involved in different karyotypic abnormalities in a variety of malignancies including melanomas and leukemias. The identification of a novel proto-oncogene that maps to that region will enable us to define whether VAV is involved in any of the translocations observed.

Cytogenetic abnormalities in acute leukemia complicating melphalan-treated multiple myeloma

The cytogenetic findings in 11 patients with multiple myeloma in whom a myelodysplastic syndrome or an acute nonlymphocytic leukemia developed are reported. All patients were treated with oral melphalan for 2-9 years in a total dose of 0.5-4.1 g. When examined during the myelodysplastic or leukemic phase, all patients had an abnormal bone marrow karyotype, hypodiploid in nine of the 11 cases. The chromosome abnormalities were clearly nonrandom and comprised a 5q deletion in three cases, monosomy 5 in four cases, deletion 7q--in two cases, and monosomy 7 in three cases. Loss of material from the long arm of chromosomes 5, 7, or both was found in eight patients. The different chromosome abnormalities were not associated with any specific morphological or clinical features.

Translocations (5;17) and (7;17) in patients with de novo or therapy-related myelodysplastic syndromes or acute nonlymphocytic leukemia. A possible association with acquired pseudo-Pelger-Huët anomaly and small vacuolated granulocytes

Twelve patients [two with de novo myelodysplastic syndrome (MDS), four with secondary MDS, five with de novo acute nonlymphocytic leukemia (ANLL), one with secondary ANLL] showed a 17p deletion resulting from translocations involving 17p: t(5;17)(p11;p11) in four cases, t(7;17)(p11;p11) in six cases, complex (5;17)(q23;p12) translocation with dicentric chromosome in one case, and t(17;?)(p11-12;?) in the remaining patient. All these structural anomalies were observed in hypodiploid clones associated with total or partial monosomy of chromosomes 5 and 7 (12 cases), monosomy 12 (five cases), monosomy 3 (four cases), and monosomy 4 (three cases). Median survival was only 3.3 months (range 3 days to 8 months). Striking features were observed in bone marrow mature granulocytes: all but one case had a pseudo-Pelger-Huët anomaly in a significant number of granulocytes, and eight patients had granulocytes with reduced size and clear cytoplasmic vacuoles. Careful cytological review of 51 patients with MDS or ANLL and various cytogenetic anomalies was performed for comparison: vacuolated granulocytes were a very uncommon finding. On the other hand, eight patients had a pseudo-Pelger-Huët anomaly, which correlated significantly with total monosomy 17 in these patients. A possible correlation between cytological anomalies and cytogenetic data is discussed, and the role of 17p in the nuclear segmentation of granulocytes is stressed.

Trisomy 19 in a patient with myelodysplastic syndrome and thrombocytosis

A patient with refractory anemia with excess blasts, ringed sideroblasts, and thrombocytosis was found on cytogenetic analysis to have trisomy 19 as the sole abnormality. Although trisomy 19 in combination with other chromosomal anomalies has been encountered in association with a variety of hematologic malignancies, many solid tumors, and the myelodysplastic syndrome, its occurrence as the only cytogenetic aberration is rare and has not been reported in association with thrombocythemia.

Biclonal chromosome evolution of chronic myelomonocytic leukemia in a child

A monosomy 7 was first detected in a 6-month-old boy with a chronic myelomonocytic leukemia. After etoposide treatment, relapse occurred after 29 months, with transformation of the disease into an acute myeloblastic leukemia. After bone marrow transplantations, two abnormal clones were found in marrow cells: 45,XY,-7,del(12)(p11p12)(66%), and 45,XY,-7,t(3;12)(q26;p12)(33%). Several karyotypic studies performed until the terminal phase exhibited the persistence of these two clones in the same proportion, although both independently acquired additional and often similar anomalies. The clone with t(3;12) acquired der(7),der(11),der(17),der(8),der(10),-5,-20, and the clone with del(12p), del(5q),der(4),der(8),der(10),der(17),-5,-20. The anomalies in 12p12 appear to represent an important although secondary event of the neoplastic process. The other anomalies may correspond to either those of a secondary acute nonlymphocytic leukemia, since they occurred after treatment by etoposide and alkylating agents, or to the natural evolution of myelomonocytic leukemia.

Cytogenetic and clinical investigations in 76 cases with therapy-related leukemia and myelodysplastic syndrome

Clinical, cytomorphologic, and cytogenetic investigations were carried out in a series of 76 secondary MDS and ANLL. Chromosome abnormalities were more frequent in patients with a history of multiple myeloma or macroglobulinemia (92%) and myeloproliferative disorders (82%) than in patients with previous breast cancer (40%). The secondary hematologic malignancies were mostly a trilineage bone marrow disorder. The most commonly found cytogenetic anomaly was monosomy 7, followed by total or partial loss of chromosome 5. In addition six other chromosomes, i.e., chromosome 3, 8, 9, 12, 17, and 21 seemed to be consistently involved in the pathogenetic mechanisms of secondary leukemia and MDS.

Confirmation and refinement of the localisation of the c-MEL locus on chromosome 19 by physical and genetic mapping

The human gene locus c-MEL was identified following transfection of genomic DNA from the human melanoma cell line NK14; it has previously been assigned to chromosome 19 (p13.2-q13.2) by analysis of somatic cell hybrids. We have further refined the position of this gene to the proximal region of 19p (cen-p13.2), using cell hybrids containing only fragments of human chromosome 19. We have confirmed this physical localisation by linkage analysis with a recently described restriction fragment length polymorphism for the c-MEL gene, and mapped the locus within the region of the low density lipoprotein receptor gene (LDLR) (Lod 4.43, theta = 0.10) and the anonymous marker D19S11 (13.1.25) (Lod 9.33, theta = 0). This gene thus maps to a region of chromosome 19 involved in karyotypic abnormalities in a variety of malignancies including melanomas and leukaemias.

Primary chromosome abnormalities in human neoplasia

At the cellular level, cancer is a genetic disease; genetic changes in somatic cells are essential events in neoplasia. In a majority of cases these changes involve large enough blocks of genetic material to be visible in the microscope. The chromosome aberrations in neoplastic disorders are probably of three kinds: (1) primary abnormalities, which are essential steps in establishing the tumor; (2) secondary abnormalities, which develop only after the tumor has developed, but which nevertheless may be important in tumor progression; and (3) cytogenetic noise, which is the background level of nonconsequential aberrations. These latter changes are, in contrast to the primary and secondary changes, randomly distributed throughout the genome. The primary abnormalities, of which several dozens have now been identified, are mostly strictly correlated with particular diseases and even with histopathological subtypes within a given disease. This has been evident in the leukemias for some years already, and information now accumulating on solid tumor karyology indicates a similar situation. Clonal chromosome abnormalities are a feature of both benign and malignant neoplasms, although the changes are often less massive in the former. Apart from being clinically useful as a diagnostic technique and an aid in prognostication, tumor cytogenetics also plays a role in identifying those genomic sites which harbor genes essential in the pathogenesis of neoplastic lesions. So far, two functionally different classes of directly cancer-relevant genes have been detected, the oncogenes and antioncogenes. There is every reason to believe that future investigations with cytogenetic and recombinant DNA methods will add to our knowledge of the biology of human neoplasia, in those tumor types where the characteristic genetic change is already partially known, and by identifying hitherto unknown karyotypic abnormalities.

Nonrandom chromosomal abnormalities in acute lymphoblastic leukemia of childhood

The leukemic cell karyotype was studied in 103 children with acute lymphoblastic leukemia. An abnormal chromosome pattern was revealed in 81 of 98 patients studied before treatment (82.6%) and in the five children studied in relapse. Aside from specific chromosomal abnormalities defined by the Third International Workshop on Chromosomes in Leukemia, other nonrandom rearrangements were observed, particularly del(14)(q11-13), del(12)(p11-12), and t(1;19)(q22-23;p13), often associated with partial trisomy for 1q. Patients with del(14) had tumorous lymph-nodes or other extramedullary tumors. The course of the disease in these children was rapid. Patients with markers such as Ph, 6q-,14q+, and with a t(4;11) had a low incidence of complete remission and short survival. The most favorable course of the disease was observed in the group of children with over 50 chromosomes in the leukemic cells.

Secondary leukemia with a translocation (8;21)?

The clinical features and cytogenetic changes of acute myeloid leukemia (AML) developing 10 years after radiotherapy and chemotherapy (for osteosarcoma) are described. Features of both de novo AML [FAB M2 morphology, t(8;21), and "secondary leukemia" (additional cytogenetic changes, resistance to chemotherapy) were present. The importance of differentiation between primary and "therapy-linked" disease, and the difficulties in making such a distinction, are discussed.

The short arm of chromosome 6 is nonrandomly rearranged in secondary myelodysplastic syndromes

Eight patients with a myelodysplastic syndrome showed a structural rearrangement of the short arm of chromosome #6 involving the distal segment 6p22----6pter. In four cases the myelodysplastic disorder appeared after treatment with chemo- and/or radiotherapy. Cytogenetically, the 6p anomaly was consistently associated with abnormalities of chromosome #5 and/or #7 in seven of eight cases. We believe we identified a new site on 6p that is nonrandomly involved in iatrogenically and possibly also environmentally induced malignant hematologic disorders.

Cytogenetic, clinical, and cytologic characteristics of radiotherapy-related leukemias

From 1978 to 1985, we observed eight cases of acute nonlymphocytic leukemia or preleukemia, three cases of acute lymphoblastic leukemia, and three cases of chronic myeloid leukemia in patients previously treated exclusively with radiotherapy for other tumor types. The latent period from administration of radiotherapy to development of leukemia varied between 12 and 243 months. Clonal chromosome aberrations reported previously as characteristic of acute nonlymphocytic leukemia following therapy with alkylating agents were observed in three of the eight patients with acute nonlymphocytic leukemia (5q- and -7) and in two of the three patients with acute lymphoblastic leukemia (-7 and 12p-). All three patients with radiotherapy-related chronic myeloid leukemia presented a t(9;22)(q34;q11). The results suggest that cytogenetic characteristics may reflect the etiology in radiation-induced acute leukemias, whereas radiation-related chronic myeloid leukemia does not seem to differ chromosomally from de novo cases of the disease.

Translocations and deletions with breakpoint on 21q are nonrandomly associated with treatment-related acute nonlymphocytic leukemia and preleukemia

Six of 70 (8.6%) consecutive cases with therapy-related acute nonlymphocytic leukemia (ANLL) or preleukemia had a translocation or deletion with a breakpoint on 21q. Such aberrations were seen in only one of 200 (0.5%) consecutive cases of de novo ANLL examined at our laboratory. The figures reflect a 17.1-fold increased incidence of 21q aberrations in therapy-related ANLL or preleukemia, compared with ANLL de novo. The difference is highly significant (p = 0.003). The increased incidence of 21q aberrations in therapy-related myelodysplastic syndromes was confirmed by literature studies. Band 21q22 was most often involved. Cases with t(8;21), which is strongly associated with the M2 variant of ANLL, or cases with i(21q), which is supposedly due to a centromeric misdivision, were not included in the count. It is concluded that the 21q aberrations are associated with treatment-related ANLL or preleukemia with at least the same degree of specificity as aberrations of #5 and #7.

Characteristic patterns of chromosome abnormalities in acute myeloid leukemia with Auer rods

Two hundred and four cytogenetically investigated patients with acute myeloid leukemia (AML) were evaluated for the presence (AR+) or absence (AR-) of Auer rods. Chromosome analysis was successful in 187 patients (92%). Seventy-eight patients (38%) were AR+. Cytogenetic abnormalities were detected in 35 (49%) AR+ patients and in 66 (57%) AR- patients. The proportion of patients with complex karyotypic changes (more than two aberrations) was significantly higher in the AR- group (p less than 0.01). Also, unidentifiable marker chromosomes were significantly more frequent in the AR- group (p less than 0.01). Twenty-one of 23 AR+, but none of 46 AR- patients with structural changes, had involvement of 21q22, 17q11-12, or 11p13-15. In contrast, structural changes of 1p, 5q, 7q, 9q, 11q, or 22q were present in 31 AR- but in only two AR+ patients. Four patients had translocations involving 21q22 without rearrangements of 8q22. All were AR+, but only one displayed M2 morphology. We draw the conclusion that chromosomal changes affecting 21q22 might be primarily related to AR formation, whereas, changes of 8q22 produce the characteristic differentiation pattern leading to M2 morphology, consistently found in AML with t(8;21)(q22;q22). With regard to numerical abnormalities, -7 and +8 occurred about equally often in the two groups, whereas, +11 and -Y, especially when present as the sole aberrations, were predominantly found in AR+ patients. In contrast, -5 and +21 were exclusively found in AR- patients. The results indicate that AR+ AML is characterized by a relatively limited number of chromosomal abnormalities that are different from the aberrations found in AR- patients. This feature has not been emphasized in previous studies correlating hematologic and cytogenetic findings in AML.

Abnormalities of chromosome 12p13 and malignant proliferation of eosinophils: a nonrandom association

Four patients representing a spectrum of haematological malignancies are reported. Two patients had Philadelphia chromosome negative myeloproliferative disorders, one had acute lymphoblastic leukaemia and one had eosinophilic leukaemia. In each case eosinophilia was present and demonstrated to be part of the malignancy by the association of clonally abnormal metaphases with eosinophil granules. Abnormalities involving the short arm of chromosome 12 (12p13) were a constant feature in all four cases and therefore a nonrandom association between this chromosome region and malignant eosinophil proliferation is proposed.

Cytogenetic characteristics of therapy-related acute nonlymphocytic leukaemia, preleukaemia and acute myeloproliferative syndrome: correlation with clinical data for 61 consecutive cases

Cytogenetic studies were performed on a new series of 23 patients with therapy-related acute non-lymphocytic leukaemia, preleukaemia or an acute myeloproliferative syndrome. In our total series of now 61 cases studied by chromosome banding techniques, at least one of the abnormalities -7, 5q-, 7q- or -5 or some related unbalanced translocations, primarily -7, +t(1q7p), was observed in 40 patients. The critical region for the deletions of chromosome no. 5 comprises bands 5q22 to 5q33 and of chromosome no. 7 bands distal to 7q22. The third most frequently involved chromosome was no. 21, rearranged at band 21q22 in the three patients with 21q+ and in one patient with 21q-. An i(21q) was observed in two patients, a -21 in four patients and a -22, +t(21q22q) and a -5, -21, +t(5p21q) in one patient each. Other characteristic abnormalities included total loss or rearrangements of the short arm of chromosome no. 17, observed in nine patients. One patient had a -12, three others had rearrangements resulting in a partial or total loss of the short arm of chromosome no. 12. A 19q+ with translocation to band 19q13 was observed in three cases, a -18 in three cases and a 3p- in four cases. Thirty-one patients with multiple chromosome aberrations experienced a significantly shorter survival as compared to 13 patients with a normal karyotype (P = 0.02) and 17 patients with one single chromosome aberration (P less than 0.01).

Cytogenetic studies in 69 patients with myelodysplastic syndromes (MDS)

Cytogenetic studies were performed in 69 patients with myelodysplastic syndromes classified according to the FAB proposals. Overall incidence of chromosomal anomalies was 48% with 5q-, +8, 12p-,-7/7q- being the aberrations most often found. The 12p- chromosome showed a close correlation with a prior exposure to mutagenic agents and CMML. Although there were no group-specific cytogenetic anomalies, FAB classification strongly influenced their incidence. They were lower (36%) in RA/RA-S than in RAEB/RAEB-T/CMML (53%). Chromosomal anomalies were significantly more often found in patients with a prior exposure to carcinogenic agents (80%) than in unexposed patients (33%). The presence of chromosomal anomalies did not predict a higher risk of leukemic transformation.

Complexity of an apparently simple variant Ph translocation in chronic myeloid leukemia

A patient with chronic myeloid leukemia (CML) presented with an apparently simple Ph translocation t(19;22)(q13;q11). In-situ hybridization revealed movement of the c-abl oncogene from a cytogenetically normal chromosome 9 to the Ph. Bcr-3' and c-sis probes hybridized to distal 1p and not to the 19q+ chromosome as expected from the cytogenetic findings. We concluded that this patient had a complex translocation involving four chromosomes: t(1;9;19;22)(p36;q34;q13;q11).

The gene encoding the T-cell surface protein T4 is located on human chromosome 12

The surface glycoproteins T4 and T8 define functionally distinct populations of T lymphocytes. We have obtained cDNA and genomic clones encoding the T4 molecule and used these as probes to determine the chromosomal location of this gene. Genomic blotting experiments, along with in situ hybridization analyses, indicate that the T4 gene resides on the short arm of human chromosome 12, at region p12-pter. Thus, the T4 gene is not linked to any known member of the immunoglobulin gene family, including its counterpart gene, T8, which resides on human chromosome 2 immediately distal to the immunoglobulin kappa locus.