Further cytogenetical investigations in polycythaemia vera

Is fluorescence in situ hybridization a useful method in diagnosis of polycythemia vera patients?

Polycythemia vera (PV) is a clonal stem cell disease with trilineage myeloid involvement, characterized by a growth factor-independent erythroid proliferation. At the time of diagnosis, the percentage of cytogenetic abnormalities using conventional cytogenetic techniques is less than 20% of all PV patients. In the present study, we compare the results between conventional cytogenetic methods and fluorescence in situ hybridization (FISH) probes in 31 untreated PV patients. The karyotypes of all 31 cases were obtained from 24-hour bone marrow cell cultures. The fixed material, proceeding from conventional cytogenetics cultures, was analyzed with FISH, using centromeric probes for chromosomes 8 and 9 and locus-specific probes for 13q14 and 20q12 regions. Five cases (17.8%) showed an abnormal karyotype with conventional cytogenetics. When FISH probes were used, three alterations not detected with conventional cytogenetics, were found: two cases with D20S108 deletions and one with a D13S319 deletion, increasing the percentage of abnormal karyotypes to 19.3%. We conclude that, probably, the application of FISH with the mentioned probes, is not very useful to detect cytogenetic aberrations in untreated PV patients.

Molecular genetics and cytogenetics of myeloproliferative disorders

The myeloproliferative disorders are believed to represent clonal malignancies resulting from transformation of a pluripotent stem cell. X-inactivation patterns of peripheral blood cells have been proposed as a useful diagnostic tool but this method is limited by the finding of a clonal X-inactivation pattern in a significant proportion of normal elderly women. There is no pathognomonic chromosomal abnormality associated with the myeloproliferative disorders. However, consistent acquired cytogenetic changes include del(20q), del(13q), trisomy 8 and 9 and duplication of segments of 1q, all of which have been observed at diagnosis or before cytoreductive therapy and therefore represent early lesions which contribute to the pathogenesis of these disorders. Although, the acquired molecular defects underlying most myeloproliferative disorders have not yet been elucidated, translocations associated with the rare 8p11 syndrome have permitted identification of a novel fusion protein. The role of a number of candidate genes in the other myeloproliferative disorders has also been studied, but no mutations have been identified so far. It is likely that a number of genes will be involved, given the varied phenotypes of the diseases. Identification of causal genes will be of considerable interest to both clinicians, who currently lack a specific and sensitive diagnostic test, and scientists interested in fundamental issues of stem cell behaviour.

Pathogenesis of polycythaemia vera

Polycythaemia vera (PV) is thought to result from clonal expansion of a transformed multipotent stem cell. Progenitors from patients with PV display abnormal responses to several growth factors, suggesting the presence of a defect in a signalling pathway common to different growth factors. A number of approaches are now focused on defining the molecular lesion or lesions. Identification of causal genes will be of considerable interest both to clinicians, who currently lack a specific and sensitive diagnostic test, and to scientists interested in fundamental issues of stem cell behaviour.

FISH studies on the Y chromosome in male urinary cells

To ascertain the meaning of the loss of the Y (-Y) in bladder cancer, we addressed the incidence of -Y in urinary cells in relation to age in 35 men without bladder cancer. Aside from the bone marrow and blood, -Y has not been examined critically in other tissues and organs in a large series of men. The present study clearly demonstrated that -Y in the group studied was an infrequent finding and not related to age.

Trisomy 14, deletion 20q and t(3;3) (q21;q26) in a case of myelodysplastic syndrome with myelofibrosis

We describe a patient with trilineage myelodysplasia and hyperplastic megakaryopoiesis associated with significant myelofibrosis at diagnosis, who developed acute myeloid leukaemia two months afterwards. The clinical and pathological features were consistent with a myelodysplasia/myelofibrosis syndrome with leukemic transformation. Cytogenetic investigation showed trisomy 14, del(20q) and t(3;3) (q21;q26). These findings are of possible significance in the understanding of the association between myelodysplasia and myelofibrosis.

Loss of the Y chromosome from normal and neoplastic bone marrows. United Kingdom Cancer Cytogenetics Group (UKCCG)

Loss of the Y chromosome is a feature of haematologically normal bone marrow in elderly males, but it is also found in haematological malignancy. We describe -Y as the sole karyotypic abnormality in 147 cases (66 from 802 unselected cases and a further 81 cases selected for -Y) with the following diagnoses: no haematological malignancy (N), myelodysplastic syndrome (MDS), acute myeloid leukaemia (AML), and myeloproliferative disorder (MPD). The frequency of -Y in the 802 unselected N, MDS, and AML cases was 7.7%, 10.7%, and 3.7%, respectively. It could not be evaluated in MPD because there were too few cases. In N and MDS cases the frequency increased in a similar fashion over the age of 60 years. The 147 -Y cases showed a similar increase in distribution with advancing age in all four clinical categories. The degree of loss of Y (% -Y cells per patient) increased with age in N and MPD patients but not in those with MDS or AML. This study suggests that in elderly men -Y is not indicative of malignancy and should not be considered as a marker of the malignant clone.

Chromosome studies in polycythemia vera patients

One hundred thirty-five polycythemia vera (PV) patients (30 untreated by chemotherapy and 105 treated) were studied cytogenetically . The incidence of clonal chromosomal abnormalities was 20.7% (28 patients in nonleukemic phase). The incidence of 20q - was 3.7% (5 patients). The presence of cytogenetically abnormal clones did not allow prediction of the evolution of the disease. In a few cases, abnormal clones disappeared at the time of later studies. Although nonrandom, the majority of clonal chromosomal abnormalities are believed to be secondary events in PV patients.

Hematologic manifestations associated with deletions of the long arm of chromosome 20

We investigated 20 patients with hematologic disorders who had a clone of cells with a deletion of most of a chromosome #20 long arm (20q-) in the bone marrow. Three patients had polycythemia vera (PV), 6 had acute nonlymphocytic leukemia (ANLL), 8 had preleukemia (PL), and 3 had other myeloproliferative disorders. In our laboratory, a 20q- chromosome is found in 6% of patients with PV, 3% of patients with ANLL, and 1% of patients with PL. Among the 6 patients with ANLL and a 20q- abnormality, 3 had erythroleukemia. There were no apparent clinical differences among our patients with 20q- chromosomes compared with other patients with similar disorders who did not have a 20q- chromosome. The breakpoint of the 20q- anomaly, in each instance, was in band 20q11, but it occurred near the centromere at 20q1101 in 16 patients and at the distal part of this band at 20q1109 in 4 patients. Three of the 4 patients with a breakpoint at 20q1109 had PL.

Chronic myelomonocytic leukemia with a chromosome abnormality (46,XY,20q-) in all dividing myeloid cells: evidence for clonal origin in a multipotent stem cell common to granulocyte, monocyte, erythrocyte, and thrombocyte

In a typical case of chronic myelomonocytic leukemia (CMML), a chromosome abnormality, 46,XY,20q-, was observed in all the dividing cells including up to 16-ploid cells in the bone marrow and the blood. As the mitotic figures could be easily seen not only in myelomonocytoid cells but also in erythroblasts in the bone marrow smear, it was concluded that all the cell lineages except lymphocytes had the abnormality. The present case will support the view that the leukemic process in CMML affects a multipotent stem cell rather than a granulocyte-monocyte committed stem cell.

Chromosomes and causation of human cancer and leukemia. LI. A hairy cell leukemia case with 14q+ and ring chromosomes: significance of ring chromosomes in blood disorders

What appears to be the first hairy cell leukemia case with a 14q+ anomaly is described. In addition to the 14q+ anomaly, a 6q- and a ring chromosome were seen in a blood sample stimulated with lipopolysaccharide, a B-cell mitogen. The clinical course of the present case was short, stormy, and had a poor response to therapy. The correlation between the clinical course and the presence of a ring chromosome in myelo- and lymphoproliferative blood disorders is discussed in relation to the various blood disorders with this karyotype anomaly described in the literature.

Cytogenetic studies in patients previously treated for Hodgkin's disease

A cytogenetic study was made of bone marrow cells and lymphocytes from patients who had been successfully treated with various regimens for Hodgkin's disease. Most of the patients had been off treatment for at least 3 years before the study began. They were divided into three groups according to the intensity of the therapy received. The frequency of gaps and breaks in the chromosomes of lymphocytes was above normal limits and similar in the three treatment groups. In contrast, the frequency of both lymphocytes and bone marrow cells with rearranged karyotypes was correlated with the intensity of treatment. Clones of cells with an abnormal karyotype were found in only two patients, both of whom were in the group receiving the most intensive therapy, i.e., chemotherapy and total nodal irradiation.

Karyotypic patterns and their clinical significance in polycythemia vera

We studied a series of 34 polycythemia vera (PV) patients to determine the incidence of chromosome abnormalities and their relationship to leukemic transformation. Metaphase chromosomes from bone marrow or unstimulated peripheral blood were examined with conventional stain and, in 20 patients, also with banding techniques. The overall incidence of clonal abnormalities in first samples was 44% (15 of 34 patients), with a higher incidence in patients who had received prior therapy. The most frequent abnormalities were long-arm deletion of No. 5 (5q-; four patients), gain of all or most of a No. 8 (five patients), gain of all or most of a No. 9 (four patients), and long-arm deletion of No. 20 (three patients); these sometimes occurred in combination. Some of the PV patients who had cytogenetic abnormalities early in the disease have had long survivals without developing leukemia. For example, one patient has been 48,XX,+8,+9 in sequential samples obtained over the last 15 years. Five patients developed acute myeloblastic leukemia (AML); each had a complex chromosomal pattern. Two of these five patients were cytogenetically normal during the polycythemic phase; the change in karyotype occurred with the leukemic transformation. Three AML patients were studied only in the leukemic phase. Three AML patients had a 5q-, and a fourth showed loss of a B-group chromosome. Evolutionary changes in the karyotype during the disease course and the occurrence of a 5q- appear to be associated with a terminal phase of PV.

Glutamic pyruvate transaminase phenotypes in polycythaemia rubra vera

Glutamate pyruvate transaminase (GPT) has been studied in the red cells of 46 patients with a confirmed diagnosis of polycythaemia rubra vera (PRV). The red cells of many of the patients showed low levels of enzyme activity. This activity could be restored by in vitro incubation with pyridoxal phosphate suggesting that the effect was due to low levels of B6 rather than to a primary abnormality of the GPT. Patients with the lowest levels of GPT activity were likely to have clonal chromosomal abnormalities in the bone marrow cells, particularly 20q-. Among 43 patients in whom the GPT phenotypes could be determined by an electrophoretic method there was a marked deficiency of heterozygotes. This disturbance in phenotypic expression may be related to the clonal nature of the disease in PRV, the clone showing lack of response to homeostatic controls and irregularities of gene expression.

Polycythemia vera: electron microscopy of the bone marrow in 10 non-treated patients. A thin section and freeze-fracture study

Electron microscopy (thin sections and freeze-fracture replicas) was performed on the bone marrow of ten patients with Polycythemia vera prior to any treatment. In addition to a hyperplasia of all three cell lineages and the sinuses, atypias were observed in the maturing erythroblasts. These aberrations of normal development consisted mainly of deep invaginations of the nuclear envelope in proerythroblasts and conspicuous nuclear clefts in erythro- and normoblasts. In comparison with similar changes in dyserythropoietic and aplastic anemia as well as leukemia these alterations are discussed in connection with disturbances of DNA synthesis. Further atypias involved megakaryopoiesis which displayed microforms probably as an evidence for maturation arrest. These ultrastructural abnormalities and their morphological features of a neoplastic proliferation of all three cell lineages in Polycythemia vera are in good agreement with the new concept of a transformation of a pluripotent stem cell with clonal character.

Chromosomes and causation of human cancer and leukemia: XXXI. Dq- deletions and their significance in proliferative disorders

Three cases with myeloproliferative disorders associated with Dq- deletions (13q- and 15q-) in their marrow cells are described. In addition, a summary of the experience with 14 cases of Dq- at Leuven, Belgium and the cases in the literature is presented. The findings indicate frequent involvement and susceptibility to deletion of the long arms of chromosomes No. 13 and No. 15 in lympho- and myeloproliferative disorders, thus adding these chromosomes to the list of those involved nonrandomly in human neoplasia.

Chromosome deletion [46,XX,del(20)(q11)] in agnogenic myeloid metaplasia

A woman in the fourth year of agnogenic myeloid metaplasia was found to have partial deletion of the long arm of chromosome 20 [46,XX,del(20)(q11)] in mitoses of presumably immature myeloid cells from unstimulated cultures of peripheral blood and bone marrow. Cytogenetic studies of peripheral blood lymphocytes showed a normal female karyotype.

[Chromosomal abnormalities in human neoplasia (author's transl)]

Multiple connections exist between chromosomal aberrations and malignant tumors. It is the aim of the present article to summarize the data known so far in view of i) cancer-prone chromosome abnormalities, ii) chromosome abnormalities related to tumors and iii) chromosome abnormalities related to carcinogens. In some instances it seemed useful to discuss the findings in man in connection with the results of in vitro experimental data.

A new cytogenetic aspect of polycythemia vera

The cytogenetic findings in a group of 15 polycythemic patients are reported. G and C banding techniques were used on bone marrow and peripheral blood preparations. Major chromosomal aberrations were found in four out of the 15 patients, an incidence similar to that found in other studies on polymorphism. The most interesting finding concerned the chromosomal polymorphism of the pair 19. A possible relation to the etiology of the disease is discussed.

Polycythaemia vera terminating in acute leukaemia. A clinical, cytogenetic and morphologic study in 8 patients treated with alkylating agents

A total of 120 patients with polycythaemia vera (PV) were observed between 1971-1976. 8 of them developed acute leukaemia (AL). The clinical course, cytogenetic and morphologic findings of these patients are described in detail. Alkylating agents were the main treatment for all patients who developed AL. 4 of them obtained alkylating drugs alone. Deaths in AL constituted 36% of the deaths observed in the groups treated with alkylating agents and 23% of the total number of deaths in these series. All patients who developed AL had active disease but they had no distinctive features predicting a malignant development. The time interval between PV diagnosis and development of AL was relatively short for those patients who were induced and maintained with alkylating agents alone. It is remarkable that 3 out of 8 patients had erythroleukaemia. Cytogenetic pretreatment studies were performed in 3 patients and all were normal. 7 patients were studied with banding techniques during the leukaemic state and all but one have shown multiple and complex abnormalities indicating several super-imposed cell lines. It seems probable that PV patients treated with alkylating agents for remission induction and maintenance may run even a greater risk for AL development than those treated with 32P.

Chromosome abnormalities after chlorambucil therapy of polycythaemia vera

Bone marrow chromosomes were studied in 2 patients with polycythaemia vera (PV) at the time of diagnosis and several times subsequently during therapy with chlorambucil. Both patients were normal in the initial study, but later developed pathological diploid cell lines with structural chromosome abnormalities. Case 1 presented after 25 months of myelosuppressive therapy a deletion of chromosome no. 12, del (12) (p11), in 60% of the diploid cells. 10 months later all studied cells in the marrow contained this deletion. In addition, the deletion of chromosome no. 20, described as characteristic for PV, was found in 3 cells. Case 2 demonstrated after 40 months on chlorambucil the presence of a balanced translocation, t (1;5) (p36;q31) in 90% of the cells. In none of the patients were any definite clinical, laboratory or morphological signs of an approaching leukaemic transformation of the polycythaemic disorder present.

Chromosome studies in untreated polycythaemia vera

Bone marrow chromosomes were studied in a series of 50 consecutive, unselected cases of untreated polycythaemia vera (PV). A pathological cell line was present in 7 patients (= 14%). 3 patients each had 1 extra chromosome no. 8 and 1 extra no. 9. 2 patients had a similar but not identical marker chromosome including material from the long arms of chromosome no. 1. 1 of these patients also had a 20q- deletion. 1 patient had an extra unidentified isochromosome. 1 patient had a monosomy 16. In 5 cases the abnormal clone dominated over cells with normal karyotype. In each of 6 patients a singular hyperdiploid cell was observed. 1 or several polyploid or randomly hypodiploid cells were found in most patients. The findings in our material are compared to other reports of chromosome studies in PV and allied disorders. Except for the 20q- deletion no abnormality typical for PV has so far been detected, but some chromosomes seem to be involved more often than others (1, 8, 9, 20). Patients with chromosome aberrations did not show any clinical, laboratory or morphologic features which could separate them from cases with normal karyotypes. The prognostic significance of the chromosome abnormalities encountered in early PV cannot be defined at present.

Abnormalities of chromosome 1 in myeloproliferative disorders

Three patients with myeloproliferative disorders showed a similar chromosome abnormality, accompanied by other abnormalities that were different in each case. Marrow cells from all three patients were trisomic either for the entire chromosome 1 or for its long arm. Patient 1 had a brief period of anemia and thrombocytopenia which preceded a terminal acute leukemia; Patient 2 had polycythemia vera (P.V.) that terminated in acute leukemia; and Patient 3 has P.V. The detection of an abnormal karyotype in Patients 1 and 2 was an important factor in establishing the diagnosis of acute leukemia. Preliminary evidence supports the suggestion that some chromosomal changes are nonrandom in myeloproliferative diseases. Nonrandom abnormalities involving the same chromosome have been observed in several human neoplastic disorders.

Chromosomes and causation of human cancer and leukemia. XII. Banding analysis of abnormal chromosomes in polycythemia vera

The chromosome constitution of bone marrow cells was determined in 13 patients with polycythemia vera (PV). In 5 of these patients definite karyotypic abnormalities were found: 3 with 46,XY,Fq-; 1 with 46,XY,11q-, 13q-; and 1 with missing Y. The latter cytogenetic finding is thought not to be related to the PV. The 4 patients with partial deletions of chromosomes had been treated with 32P, and 3 of them with chemotherapy also. Karyotypes from 2 of these patients, 1 with 46,XY,20q-, and another with 46,XY,11q-,13q- were examined with G and/or Q banding. From the results of the banding analysis, it appears that the abnormal chromosomes were due to simple deletions at specific sites on their arms, particularly in the cases with the F abnormality (20q11). The breaks occurred in the regions C11q and D12q. The portions missing from the original chromosomes could not be found on any chromosome. Most patients with PV do not develop chromosomal abnormalities through the course of their disease; when such abnormalities appear (20q- in particular), they seem to result exclusively from radiation (and possibly chemo-) therapy. Thus, cytogenetic changes do not appear to play a crucial role in the genesis of PV.

Two populations of Rh groups together with chromosomally abnormal cell lines in the bone marrow

At the onset of his disease a man with polycythaemia vera had chromosomally normal cells in the bone marrow and Rh blood group CDe/cDE. Five years later he developed pancytopenia with erythroid hyperplasia of the bone marrow. This was associated with the presence of a major abnormal clone, 45,XY,B-,C-,16+, a minor clone, 45,XY,2+,3-,C-, and a few apparently normal cells. At the same time Rh blood grouping showed two populations of red cells, one CDe/cDE and one giving the reactions of CDe/CDe which can be interpreted as CDe. If monosomic CDe be the correct interpretation the case provides a strong hint that the Rh complex locus is sited either on the long arm of a B-group chromosome or, less probably, on an autosome of the C group.